JP7508410B2 - Work Machine - Google Patents

Description

The present invention relates to work machines such as skid steer loaders, compact track loaders, and backhoes.

A conventional technique for decelerating and accelerating a working machine is disclosed in Patent Document 1. The working machine in Patent Document 1 includes a prime mover including an engine, a hydraulic pump that is operated by the power of the prime mover and discharges hydraulic oil, a traveling hydraulic device whose speed can be changed between a first speed and a second speed that is faster than the first speed depending on the pressure of the hydraulic oil, an actuating valve that can change the pressure of the hydraulic oil acting on the traveling hydraulic device, and a measuring device that can detect the pressure of the hydraulic oil. When the detected pressure, which is the pressure of the hydraulic oil detected by the measuring device, drops from the set pressure corresponding to the second speed to a predetermined pressure or lower, the actuating valve reduces the pressure of the hydraulic oil acting on the traveling hydraulic device to decelerate the traveling hydraulic device to the first speed.

JP 2017-179923 A

In the working machine of Patent Document 1, when the pressure of the hydraulic oil supplied to the traveling device during traveling is equal to or higher than a predetermined value, the working machine can automatically decelerate from the second speed to the first speed. In recent years, there has been a demand for determining the traveling direction of the working machine (traveling device), i.e., the operation direction of the traveling operation member.
The present invention has been made to solve the problems of the conventional technology as described above, and aims to provide a work machine that makes it possible to easily determine the operation direction of a travel operating member that can control the travel of the machine body.

The technical means adopted by the present invention to solve the technical problems are as follows.
In one aspect of the present invention, a work machine includes a body, a left traveling device provided on the left side of the body, a right traveling device provided on the right side of the body, a left traveling motor capable of transmitting power to the left traveling device, a right traveling motor capable of transmitting power to the right traveling device, a left traveling pump having a first pressure receiving portion and a second pressure receiving portion that receive hydraulic oil under pressure and that supplies hydraulic oil to the left traveling motor when hydraulic oil acts on at least either the first pressure receiving portion or the second pressure receiving portion, and a third pressure receiving portion and a fourth pressure receiving portion that receive hydraulic oil under pressure, a right travel pump that supplies hydraulic oil to the right travel motor when hydraulic oil acts on at least one of the third pressure receiving portion and the fourth pressure receiving portion; a travel operation device that applies hydraulic oil to at least one of the first pressure receiving portion, the second pressure receiving portion, the third pressure receiving portion and the fourth pressure receiving portion when the travel operation member is operated; a first travel oil passage that is connected to the first pressure receiving portion and that passes hydraulic oil that acts on the first pressure receiving portion when the travel operation member is operated; a second travel oil passage that passes a hydraulic oil used for travelling, a third travel oil passage that is connected to the third pressure receiving part and that passes a hydraulic oil that acts on the third pressure receiving part when a travel operating member is operated, a fourth travel oil passage that is connected to the fourth pressure receiving part and that passes a hydraulic oil that acts on the fourth pressure receiving part when a travel operating member is operated, a first pressure detection device that can detect a first pilot pressure that is the pressure of the hydraulic oil in the first travel oil passage, a second pressure detection device that can detect a second pilot pressure that is the pressure of the hydraulic oil in the second travel oil passage, a third pressure detection device that can detect a third pilot pressure that is the pressure of the hydraulic oil in the third travel oil passage, a fourth pressure detection device that can detect a fourth pilot pressure that is the pressure of the hydraulic oil in the fourth travel oil passage, and a control device that determines the operation direction of the travel operating member based on either first comparison information including a comparison between the first pilot pressure and the second pilot pressure acting on the left travel pump, or second comparison information including a comparison between the third pilot pressure and the fourth pilot pressure acting on the right travel pump.

In addition, the control device determines that the operation direction of the travel operating member is other than the reverse side when the first comparison information indicates that the first pilot pressure is greater than the second pilot pressure and the ratio of the second pilot pressure to the first pilot pressure is less than a first threshold value.
In addition, the control device determines that the operation direction of the travel operating member is other than the reverse side when the second comparison information indicates that the third pilot pressure is greater than the fourth pilot pressure and the ratio of the fourth pilot pressure to the third pilot pressure is less than a second threshold value.

The control device also determines that the operation direction of the travel operating member is the reverse side when the first comparison information indicates that the first pilot pressure is equal to or lower than the second pilot pressure, or the ratio of the second pilot pressure to the first pilot pressure is equal to or higher than a first threshold value, and the second comparison information indicates that the third pilot pressure is equal to or lower than the fourth pilot pressure, or the ratio of the fourth pilot pressure to the third pilot pressure is equal to or higher than a second threshold value.

In addition, the control device determines that the operation direction of the travel operating member is other than the forward side when the first comparison information indicates that the second pilot pressure is greater than the first pilot pressure and the ratio of the first pilot pressure to the second pilot pressure is less than a first threshold value.
In addition, the control device determines that the operation direction of the travel operating member is other than the forward side when the second comparison information indicates that the fourth pilot pressure is greater than the third pilot pressure and the ratio of the third pilot pressure to the fourth pilot pressure is less than a second threshold value.

The control device also determines that the operation direction of the travel operating member is the forward direction when the first comparison information indicates that the second pilot pressure is equal to or lower than the first pilot pressure, or the ratio of the first pilot pressure to the second pilot pressure is equal to or higher than a first threshold value, and the second comparison information indicates that the fourth pilot pressure is equal to or lower than the third pilot pressure, or the ratio of the third pilot pressure to the fourth pilot pressure is equal to or higher than a second threshold value.

In addition, the control device determines that the operation direction of the traveling operating member is other than the left turning side when the first comparison information indicates that the first pilot pressure is greater than the second pilot pressure and the ratio of the second pilot pressure to the first pilot pressure is less than a first threshold value.
In addition, the control device determines that the operation direction of the traveling operating member is other than the left turning side when the second comparison information indicates that the fourth pilot pressure is greater than the third pilot pressure and the ratio of the third pilot pressure to the fourth pilot pressure is less than a second threshold value.

The control device also determines that the operation direction of the travel operating member is the left turning side when the first comparison information indicates that the first pilot pressure is equal to or lower than the second pilot pressure, or the ratio of the second pilot pressure to the first pilot pressure is equal to or higher than a first threshold value, and the second comparison information indicates that the fourth pilot pressure is equal to or lower than the third pilot pressure, or the ratio of the third pilot pressure to the fourth pilot pressure is equal to or higher than a second threshold value.

In addition, the control device determines that the operation direction of the traveling operating member is other than the right turning side when the first comparison information indicates that the second pilot pressure is greater than the first pilot pressure and the ratio of the first pilot pressure to the second pilot pressure is less than a first threshold value.
In addition, the control device determines that the operation direction of the traveling operating member is other than the right turn side when the second comparison information indicates that the third pilot pressure is greater than the fourth pilot pressure and the ratio of the fourth pilot pressure to the third pilot pressure is less than a second threshold value.

The control device also determines that the operation direction of the travel operating member is the right turn side when the first comparison information indicates that the second pilot pressure is equal to or lower than the first pilot pressure, or the ratio of the first pilot pressure to the second pilot pressure is equal to or higher than a first threshold value, and the second comparison information indicates that the third pilot pressure is equal to or lower than the fourth pilot pressure, or the ratio of the fourth pilot pressure to the third pilot pressure is equal to or higher than a second threshold value.

In another aspect of the present invention, a work machine includes a body, a left traveling device provided on the left side of the body, a right traveling device provided on the right side of the body, a left traveling motor capable of transmitting power to the left traveling device, a right traveling motor capable of transmitting power to the right traveling device, a left traveling pump having a first pressure receiving portion and a second pressure receiving portion that receive hydraulic oil under pressure and that supplies hydraulic oil to the left traveling motor when hydraulic oil acts on at least either the first pressure receiving portion or the second pressure receiving portion, and a third pressure receiving portion and a fourth pressure receiving portion that receive hydraulic oil under pressure and at least a right travel pump that supplies hydraulic oil to the right travel motor when hydraulic oil acts on either the third pressure receiving portion or the fourth pressure receiving portion; a travel operation device that applies hydraulic oil to at least either the first pressure receiving portion, the second pressure receiving portion, the third pressure receiving portion, or the fourth pressure receiving portion when the travel operation member is operated; a first travel oil passage that is connected to the first pressure receiving portion and that passes hydraulic oil that acts on the first pressure receiving portion when the travel operation member is operated; and a second travel oil passage that is connected to the second pressure receiving portion and that passes hydraulic oil that acts on the second pressure receiving portion when the travel operation member is operated. a second travel oil line, a third travel oil line connected to the third pressure receiving part and passing hydraulic oil acting on the third pressure receiving part when a travel operation member is operated; a fourth travel oil line connected to the fourth pressure receiving part and passing hydraulic oil acting on the fourth pressure receiving part when a travel operation member is operated; a first pressure detection device capable of detecting a first pilot pressure which is the pressure of hydraulic oil in the first travel oil line; a second pressure detection device capable of detecting a second pilot pressure which is the pressure of hydraulic oil in the second travel oil line; The system includes a third pressure detection device capable of detecting the pilot pressure, a fourth pressure detection device capable of detecting a fourth pilot pressure, which is the pressure of the hydraulic oil in the fourth traveling oil passage, and a control device that determines the operation direction of the traveling operation member based on either third comparison information including a comparison between the first pilot pressure acting on the left traveling pump and the fourth pilot pressure acting on the right traveling pump, or fourth comparison information including a comparison between the second pilot pressure acting on the left traveling pump and the third pilot pressure acting on the right traveling pump.

The first travel oil passage has a first throttling portion downstream of the first pressure detection device that limits the flow rate of the hydraulic oil. The second travel oil passage has a second throttling portion downstream of the second pressure detection device that limits the flow rate of the hydraulic oil. The third travel oil passage has a third throttling portion downstream of the third pressure detection device that limits the flow rate of the hydraulic oil. The fourth travel oil passage has a fourth throttling portion downstream of the fourth pressure detection device that limits the flow rate of the hydraulic oil.

The present invention makes it possible to easily and accurately determine the direction of operation of the travel control member that controls the travel of the aircraft.

1 is a diagram showing a hydraulic system (hydraulic circuit) of a work machine according to a first embodiment of the present invention. FIG. 5A to 5C are diagrams showing operation directions of a travel operation member according to the first embodiment, etc.; FIG. 2 is a diagram showing the relationship between the operation direction when a travel operating member is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in FIG. 1 relating to the first embodiment. 4 is an operational flow for determining an operation direction of a travel operating member based on a relationship between the operation direction and the pilot pressure shown in FIG. 3 according to the first embodiment. FIG. 2 is a diagram showing a hydraulic system (hydraulic circuit) of a work machine according to a first embodiment, which is different from that shown in FIG. 1 . FIG. 7 is a diagram showing the relationship between the operation direction when the travel operating member is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in FIG. 5 relating to the first embodiment. 7 is an operational flow for determining the operation direction of a travel operating member based on the relationship between the operation direction and the pilot pressure shown in FIG. 6 according to the first embodiment. FIG. 11 is a diagram showing the relationship between the operation direction when a travel operating member is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in FIG. 1 according to the second embodiment of the present invention. 9 is an operational flow for determining the operation direction of a travel operating member based on the relationship between the operation direction and the pilot pressure shown in FIG. 8 according to the second embodiment. FIG. 7 is a diagram showing the relationship between the operation direction when the travel operating member is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in FIG. 5 relating to the second embodiment. 11 is an operational flow for determining the operation direction of a travel operating member based on the relationship between the operation direction and the pilot pressure shown in FIG. 10 according to the second embodiment. FIG. 11 is a diagram showing the relationship between the operation direction when a travel operating member is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in FIG. 1 according to the third embodiment of the present invention. 13 is an operational flow for determining the operation direction of a travel operating member based on the relationship between the operation direction and the pilot pressure shown in FIG. 12 according to the third embodiment. FIG. 11 is a diagram showing the relationship between the operation direction when the travel operating member is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in FIG. 5 relating to the third embodiment. 15 is an operational flow for determining the operation direction of a travel operating member based on the relationship between the operation direction and the pilot pressure shown in FIG. 14 according to the third embodiment. 13 is an operational flow for determining the operation direction of a travel operating member based on the relationship between the operation direction and the pilot pressure shown in FIG. 12 according to the third embodiment. 15 is an operational flow for determining the operation direction of a travel operating member based on the relationship between the operation direction and the pilot pressure shown in FIG. 14 according to the third embodiment. FIG. 1 is a side view showing a track loader, which is an example of a work machine according to first to third embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a hydraulic system for a work machine and a work machine equipped with this hydraulic system according to the present invention will be described with reference to the drawings as appropriate.
First Embodiment
Fig. 10 shows a side view of a working machine according to the present invention. Fig. 10 shows a compact track loader as an example of a working machine. However, the working machine according to the present invention is not limited to a compact track loader, and may be, for example, another type of loader working machine, such as a skid steer loader. Also, the working machine may be a working machine other than a loader working machine.

As shown in FIG. 10, the working machine 1 includes a machine body 2, a cabin 3, a working device 4, and a pair of traveling devices 5L and 5R. In the embodiment of the present invention, the front side (left side in FIG. 10) of the driver seated in the driver's seat 8 of the working machine 1 is described as the front, the rear side of the driver (right side in FIG. 10) is described as the rear, the left side of the driver (near side in FIG. 10) is described as the left side, and the right side of the driver (rear side in FIG. 10) is described as the right side. In addition, the horizontal direction perpendicular to the front-to-rear direction is described as the machine body width direction. The direction from the center of the machine body 2 to the right or left side is described as the machine body outside. In other words, the machine body outside is the machine body width direction, and is the direction away from the machine body 2. The opposite direction to the machine body outside is described as the machine body inside. In other words, the machine body inside is the machine body width direction, and is the direction approaching the machine body 2.

The cabin 3 is mounted on the machine body 2. A driver's seat 8 is provided in the cabin 3. The work device 4 is attached to the machine body 2. A pair of traveling devices 5L, 5R are provided on the outside of the machine body 2. A prime mover 32 is mounted at the rear inside the machine body 2.
The work device 4 has a boom 10 , a work implement 11 , a lift link 12 , a control link 13 , a boom cylinder 14 , and a bucket cylinder 15 .

The boom 10 is mounted on the right and left sides of the cabin 3 so as to be able to swing up and down. The work implement 11 is, for example, a bucket, which is mounted on the tip (front end) of the boom 10 so as to be able to swing up and down. The lift link 12 and the control link 13 support the base (rear) of the boom 10 so that the boom 10 can swing up and down. The boom cylinder 14 raises and lowers the boom 10 by extending and retracting. The bucket cylinder 15 swings the bucket 11 by extending and retracting.

The front portions of the left and right booms 10 are connected to each other by a connecting pipe having an irregular shape, and the base portions (rear portions) of the booms 10 are connected to each other by a circular connecting pipe.
The lift link 12, the control link 13 and the boom cylinder 14 are provided on the left and right sides of the aircraft 2 corresponding to the left and right booms 10, respectively.
The lift link 12 is provided vertically at the rear of the base of each boom 10. An upper portion (one end side) of this lift link 12 is pivoted rotatably about a horizontal axis via a pivot shaft 16 (first pivot shaft) near the rear of the base of each boom 10. Meanwhile, a lower portion (the other end side) of the lift link 12 is pivoted rotatably about a horizontal axis via a pivot shaft 17 (second pivot shaft) near the rear of the aircraft body 2. The second pivot shaft 17 is provided below the first pivot shaft 16.

The upper part of the boom cylinder 14 is pivoted so as to be rotatable about a horizontal axis via a pivot shaft 18 (third pivot shaft). The third pivot shaft 18 is the base of each boom 10 and is provided at the front of the base. The lower part of the boom cylinder 14 is pivoted so as to be rotatable about a horizontal axis via a pivot shaft 19 (fourth pivot shaft). The fourth pivot shaft 19 is provided below the third pivot shaft 18, toward the lower rear of the machine body 2.

The control link 13 is provided in front of the lift link 12. One end of the control link 13 is pivoted to rotate freely around a horizontal axis via a pivot shaft 20 (fifth pivot shaft). The fifth pivot shaft 20 is provided on the aircraft body 2 at a position corresponding to the front of the lift link 12. The other end of the control link 13 is pivoted to rotate freely around a horizontal axis via a pivot shaft 21 (sixth pivot shaft). The sixth pivot shaft 21 is provided on the boom 10 in front of and above the second pivot shaft 17.

By extending and retracting the boom cylinder 14, the base of each boom 10 is supported by the lift link 12 and the control link 13, while each boom 10 swings up and down around the first pivot shaft 16, and the tip of each boom 10 rises and falls. The control link 13 swings up and down around the fifth pivot shaft 20 in conjunction with the up and down swing of each boom 10. The lift link 12 swings back and forth around the second pivot shaft 17 in conjunction with the up and down swing of the control link 13.

Instead of the bucket 11, another working tool can be attached to the front of the boom 10. The other working tool can be, for example, an attachment (spare attachment) such as a hydraulic crusher, a hydraulic breaker, an angle broom, an earth auger, a pallet fork, a sweeper, a mower, or a snow blower.
A connecting member 50 is provided at the front of the left boom 10. The connecting member 50 is a device that connects hydraulic equipment provided on the spare attachment to a first tubular member such as a pipe provided on the boom 10. Specifically, the first tubular member can be connected to one end of the connecting member 50, and the second tubular member connected to the hydraulic equipment of the spare attachment can be connected to the other end. As a result, the hydraulic oil flowing through the first tubular member passes through the second tubular member and is supplied to the hydraulic equipment.

The bucket cylinders 15 are disposed near the front of each boom 10. By extending and contracting the bucket cylinders 15, the bucket 11 is swung.
Of the pair of traveling devices 5L, 5R, the traveling device 5L is provided on the left side of the machine body 2, and the traveling device 5R is provided on the right side of the machine body 2. In this embodiment, a crawler type (including a semi-crawler type) traveling device is used as the pair of traveling devices 5L, 5R. Note that a wheel type traveling device having front and rear wheels may also be used. Hereinafter, for convenience of explanation, the traveling device 5L may be referred to as the left traveling device 5L, and the traveling device 5R may be referred to as the right traveling device 5R.

The prime mover 32 is an internal combustion engine such as a diesel engine or a gasoline engine, an electric motor, etc. In this embodiment, the prime mover 32 is a diesel engine, but is not limited to this.
Next, the hydraulic system of the work machine will be described.
As shown in FIG. 1, the hydraulic system of the work machine includes a first hydraulic pump P1 and a second hydraulic pump P2. The first hydraulic pump P1 is a pump driven by the power of a prime mover 32, and is configured by a fixed displacement gear pump. The first hydraulic pump P1 is capable of discharging hydraulic oil stored in a tank 22. In particular, the first hydraulic pump P1 discharges hydraulic oil mainly used for control. For convenience of explanation, the tank 22 that stores hydraulic oil may be referred to as a hydraulic oil tank. In addition, of the hydraulic oil discharged from the first hydraulic pump P1, the hydraulic oil used for control may be referred to as pilot oil, and the pressure of the pilot oil may be referred to as pilot pressure.

The second hydraulic pump P2 is a pump driven by the power of the prime mover 32 and is configured as a fixed displacement gear pump. The second hydraulic pump P2 is capable of discharging hydraulic oil stored in the tank 22, and supplies hydraulic oil to, for example, an oil passage of the work system. For example, the second hydraulic pump P2 supplies hydraulic oil to the boom cylinder 14 that operates the boom 10, the bucket cylinder 15 that operates the bucket, and a control valve (flow control valve) that controls a standby hydraulic actuator that operates a standby hydraulic actuator.

The hydraulic system of the work machine also includes a pair of travel motors 36L, 36R and a pair of travel pumps 53L, 53R. The pair of travel motors 36L, 36R are motors that transmit power to the pair of travel devices 5L, 5R. Of the pair of travel motors 36L, 36R, one travel motor 36L transmits rotational power to the travel device (left travel device) 5L, and the other travel motor 36R transmits rotational power to the travel device (right travel device) 5R.

The pair of travel pumps 53L, 53R are pumps driven by the power of the prime mover 32, and are, for example, swash plate type variable displacement axial pumps. When driven, the pair of travel pumps 53L, 53R supply hydraulic oil to each of the pair of travel motors 36L, 36R. Of the pair of travel pumps 53L, 53R, one travel pump 53L supplies hydraulic oil to the travel pump 53L, and the other travel pump 53R supplies hydraulic oil to the travel pump 53R.

Hereinafter, for ease of explanation, the travel pump 53L may be referred to as the left travel pump 53L, the travel pump 53R may be referred to as the right travel pump 53R, the travel motor 36L may be referred to as the left travel motor 36L, and the travel motor 36R may be referred to as the right travel motor 36R.
The left traveling pump 53L and the right traveling pump 53R have pressure receiving parts 53a and 53b on which the pressure (pilot pressure) of the hydraulic oil (pilot oil) from the first hydraulic pump P1 acts, and the angle of the swash plate is changed by the pilot pressure acting on the pressure receiving parts 53a and 53b. By changing the angle of the swash plate, the output (discharge amount of hydraulic oil) of the left traveling pump 53L and the right traveling pump 53R and the discharge direction of the hydraulic oil can be changed.

The left traveling pump 53L and the left traveling motor 36L are connected by a connecting oil passage 57h, and hydraulic oil discharged by the left traveling pump 53L is supplied to the left traveling motor 36L. The right traveling pump 53R and the right traveling motor 36R are connected by a connecting oil passage 57i, and hydraulic oil discharged by the right traveling pump 53R is supplied to the right traveling motor 36R.
The left traveling motor 36L can be rotated by hydraulic oil discharged from the left traveling pump 53L, and the rotation speed (number of rotations) can be changed by the flow rate of the hydraulic oil. The left traveling motor 36L is connected to a swash plate switching cylinder 37L, and the rotation speed (number of rotations) of the left traveling motor 36L can also be changed by expanding or contracting the swash plate switching cylinder 37L to one side or the other side. That is, when the swash plate switching cylinder 37L is contracted, the rotation speed of the left traveling motor 36L is set to a low speed (first speed), and when the swash plate switching cylinder 37L is expanded, the rotation speed of the left traveling motor 36L is set to a high speed (second speed). That is, the rotation speed of the left traveling motor 36L can be changed between a first speed, which is a low speed, and a second speed, which is a high speed.

The right traveling motor 36R can be rotated by hydraulic oil discharged from the right traveling pump 53R, and the rotation speed (number of rotations) can be changed by the flow rate of the hydraulic oil. A swash plate switching cylinder 37R is connected to the right traveling motor 36R, and the rotation speed (number of rotations) of the right traveling motor 36R can also be changed by expanding or contracting the swash plate switching cylinder 37R to one side or the other side. That is, when the swash plate switching cylinder 37R is contracted, the rotation speed of the right traveling motor 36R is set to a low speed (first speed), and when the swash plate switching cylinder 37R is expanded, the rotation speed of the right traveling motor 36R is set to a high speed (second speed). That is, the rotation speed of the right traveling motor 36R can be changed between a first speed, which is a low speed, and a second speed, which is a high speed.

1, the hydraulic system of the work machine includes a travel switching valve 34. The travel switching valve 34 is switchable between a first state in which the rotation speed (revolutions) of the travel motors (left travel motor 36L, right travel motor 36R) is set to a first speed, and a second state in which the rotation speed (revolutions) is set to a second speed. The travel switching valve 34 includes first switching valves 71L, 71R and a second switching valve 72.
The first switching valve 71L is connected to the swash plate switching cylinder 37L of the left traveling motor 36L via an oil passage and is a two-position switching valve that can be switched between a first position 71L1 and a second position 71L2. When the first switching valve 71L is in the first position 71L1, the swash plate switching cylinder 37L is contracted, and when the first switching valve 71L is in the second position 71L2, the swash plate switching cylinder 37L is extended.

The first switching valve 71R is connected to the swash plate switching cylinder 37R of the right traveling motor 36R via an oil passage and is a two-position switching valve that can be switched between a first position 71R1 and a second position 71R2. When the first switching valve 71R is in the first position 71R1, the swash plate switching cylinder 37R is contracted, and when the first switching valve 71R is in the second position 71R2, the swash plate switching cylinder 37R is extended.
The second switching valve 72 is a solenoid valve that switches the first switching valve 71L and the first switching valve 71R, and is a two-position switching valve that can be switched between a first position 72a and a second position 72b by excitation. The second switching valve 72, the first switching valve 71L, and the first switching valve 71R are connected by an oil passage 41. When the second switching valve 72 is in the first position 72a, the second switching valve 72 switches the first switching valve 71L and the first switching valve 71R to the first positions 71L1 and 71R1, and when the second position 72b, the second switching valve 72 switches the first switching valve 71L and the first switching valve 71R to the second positions 71L2 and 71R2.

In other words, when the second switching valve 72 is in the first position 72a, the first switching valve 71L is in the first position 71L1, and the first switching valve 71R is in the first position 71R1, the travel switching valve 34 is in the first state, and the rotation speed of the travel motors (left travel motor 36L, right travel motor 36R) is set to the first speed. When the second switching valve 72 is in the second position 72b, the first switching valve 71L is in the second position 71L2, and the first switching valve 71R is in the second position 71R2, the travel switching valve 34 is in the second state, and the rotation speed of the travel motors (left travel motor 36L, right travel motor 36R) is set to the second speed.

Therefore, the travel switch valve 34 can switch the travel motors (left travel motor 36L, right travel motor 36R) between a first speed, which is a low speed, and a second speed, which is a high speed.
The operation device (travel operation device) 54 is a device that applies hydraulic oil to the pressure receiving parts 53a, 53b of the travel pumps (left travel pump 53L, right travel pump 53R) when the travel operation member 59 is operated, and can change the angle of the swash plate (swash plate angle) of the travel pump. The operation device 54 includes the travel operation member 59 and a plurality of operation valves 55.

The travel operation member 59 is an operating lever that is supported by the operating valve 55 and swings left and right (machine width direction) or forward and backward. That is, the travel operation member 59 can be operated to the right and left from the neutral position N as a reference, and can also be operated forward and backward from the neutral position N. In other words, the travel operation member 59 can swing in at least four directions based on the neutral position N. For ease of explanation, both forward and backward directions, i.e., the forward and backward directions, are referred to as the first direction. Also, both right and left directions, i.e., the left and right directions (machine width direction), are sometimes referred to as the second direction.

The multiple operating valves 55 are operated in common, i.e., by a single travel operating member 59. The multiple operating valves 55 operate based on the oscillation of the travel operating member 59. A discharge oil passage 40 is connected to the multiple operating valves 55, and hydraulic oil (pilot oil) can be supplied from the first hydraulic pump P1 via the discharge oil passage 40. The multiple operating valves 55 are operating valve 55A, operating valve 55B, operating valve 55C, and operating valve 55D.

In the forward and backward directions (first direction), when the travel operating member 59 is swung forward (one side) (when operated forward), the pressure of the hydraulic oil output by the operating valve 55A changes according to the operation amount (operation) of the forward operation. In the forward and backward directions (first direction), when the travel operating member 59 is swung backward (the other side) (when operated backward), the pressure of the hydraulic oil output by the operating valve 55B changes according to the operation amount (operation) of the backward operation. In the left-right directions (second direction), when the travel operating member 59 is swung right (one side) (when operated right), the pressure of the hydraulic oil output by the operating valve 55C changes according to the operation amount (operation) of the right operation. In the left-right directions (second direction), when the travel operating member 59 is swung left (the other side) (when operated left), the pressure of the hydraulic oil output by the operating valve 55D changes according to the operation amount (operation) of the left operation.

The multiple operating valves 55 and the travel pumps (left travel pump 53L, right travel pump 53R) are connected by the travel oil passage 45. In other words, the travel pumps (left travel pump 53L, right travel pump 53R) are hydraulic devices that can be operated by hydraulic oil output from the operating valves 55 (operation valve 55A, operation valve 55B, operation valve 55C, operation valve 55D).
The travel oil passage 45 has a first travel oil passage 45a, a second travel oil passage 45b, a third travel oil passage 45c, a fourth travel oil passage 45d, and a fifth travel oil passage 45e.

The first traveling oil passage 45a is an oil passage connected to the pressure receiving part (first pressure receiving part) 53a of the left traveling pump 53L, and is an oil passage through which hydraulic oil acting on the pressure receiving part (first pressure receiving part) 53a passes when the traveling operating member 59 is operated.
The second traveling oil passage 45b is an oil passage connected to the pressure receiving part (second pressure receiving part) 53b of the left traveling pump 53L, and is an oil passage that passes hydraulic oil acting on the pressure receiving part (second pressure receiving part) 53b when the traveling operating member 59 is operated.

The third traveling oil passage 45c is an oil passage connected to the pressure receiving portion (third pressure receiving portion) 53a of the right traveling pump 53R, and is an oil passage that passes hydraulic oil acting on the pressure receiving portion (third pressure receiving portion) 53a when the traveling operating member 59 is operated.
The fourth traveling oil passage 45d is an oil passage connected to the pressure receiving portion (fourth pressure receiving portion) 53b of the right traveling pump 53R, and is an oil passage that passes hydraulic oil acting on the pressure receiving portion (fourth pressure receiving portion) 53b when the traveling operating member 59 is operated.

The fifth travel oil passage 45e is an oil passage that connects the operation valve 55, the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the fourth travel oil passage 45d. The fifth travel oil passage 45e is provided with a plurality of high pressure selection valves 47a, 47b, 47c, and 47d.
The multiple high pressure selection valves 47a, 47b, 47c, 47d are connected to the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the fourth travel oil passage 45d, and flow the hydraulic oil to the one with the higher hydraulic oil pressure (pilot pressure).

When the travel operating member 59 is swung forward (in the direction of the arrow A1 in FIGS. 1 and 2), the operating valve 55A is operated and pilot pressure is output from the operating valve 55A. This pilot pressure acts on the pressure receiving portion 53a of the left travel pump 53L via the first travel oil passage 45a and also acts on the pressure receiving portion 53a of the right travel pump 53R via the third travel oil passage 45c.
As a result, the swash plate angles of the left travel pump 53L and the right travel pump 53R are changed, the left travel motor 36L and the right travel motor 36R rotate forward (forward rotation), and the work machine 1 moves straight forward.

In addition, when the travel operating member 59 is swung backward (in the direction of the arrow A2 in FIGS. 1 and 2), the operating valve 55B is operated and pilot pressure is output from the operating valve 55B. This pilot pressure acts on the pressure receiving portion 53b of the left travel pump 53L via the second travel oil passage 45b and also acts on the pressure receiving portion 53b of the right travel pump 53R via the fourth travel oil passage 45d.
As a result, the swash plate angles of the left travel pump 53L and the right travel pump 53R are changed, the left travel motor 36L and the right travel motor 36R rotate in the reverse direction (reverse rotation), and the work machine 1 moves straight backward.

In addition, when the travel operating member 59 is swung to the right (the direction of the arrow A3 in Figs. 1 and 2), the operating valve 55C is operated and pilot pressure is output from the operating valve 55C. This pilot pressure acts on the pressure receiving portion 53a of the left travel pump 53L via the first travel oil passage 45a and also acts on the pressure receiving portion 53b of the right travel pump 53R via the fourth travel oil passage 45d.
As a result, the swash plate angles of the left travel pump 53L and the right travel pump 53R are changed, the left travel motor 36L rotates forward and the right travel motor 36R rotates reversely, and the work machine 1 makes a spin turn (pilot turn) to the right.

In addition, when the travel operating member 59 is swung to the left (in the direction of the arrow A4 in Figs. 1 and 2), the operating valve 55D is operated and pilot pressure is output from the operating valve 55D. This pilot pressure acts on the pressure receiving portion 53a of the right travel pump 53R via the third travel oil passage 45c and also acts on the pressure receiving portion 53b of the left travel pump 53L via the second travel oil passage 45b.
As a result, the swash plate angles of the left travel pump 53L and the right travel pump 53R are changed, the left travel motor 36L rotates in the reverse direction and the right travel motor 36R rotates in the forward direction, and the work machine 1 makes a spin turn (pilot turn) to the left.

In addition, when the travel operating member 59 is swung diagonally (in the direction of arrow A5 in Figure 2), the rotation direction and rotation speed of the left travel motor 36L and the right travel motor 36R are determined by the differential pressure of the pilot pressure acting on the pressure receiving portion 53a and the pressure receiving portion 53b, and the work machine 1 makes a right pivot turn or a left pivot turn while moving forward or backward.
In other words, when the travel operating member 59 is swung diagonally forward to the left, the work machine 1 turns left while moving forward at a speed corresponding to the swing angle of the travel operating member 59, when the travel operating member 59 is swung diagonally forward to the right, the work machine 1 turns right while moving forward at a speed corresponding to the swing angle of the travel operating member 59, when the travel operating member 59 is swung diagonally backward to the left, the work machine 1 turns left while moving backward at a speed corresponding to the swing angle of the travel operating member 59, and when the travel operating member 59 is swung diagonally backward to the right, the work machine 1 turns right while moving backward at a speed corresponding to the swing angle of the travel operating member 59.

As shown in Fig. 1, the work machine 1 is equipped with a control device 60. The control device 60 performs various controls of the work machine 1, and is composed of semiconductors such as a CPU and an MPU, electric and electronic circuits, etc. An accelerator 65, a mode switch 66, a speed change switch 67, and a rotation speed detection device 68 are connected to the control device 60.
The mode switch 66 is a switch that switches automatic deceleration between enabled and disabled. For example, the mode switch 66 is a switch that can be switched ON/OFF, and switches automatic deceleration to enabled when the mode switch 66 is ON, and switches automatic deceleration to disabled when the mode switch 66 is OFF.

The speed change switch 67 is provided near the driver's seat 8 and can be operated by the driver (operator). The speed change switch 67 is a switch that can manually switch the traveling motors (left traveling motor 36L, right traveling motor 36R) between a first speed and a second speed.
For example, the speed change switch 67 is a seesaw switch that switches between a first speed side and a second speed side, and can perform an accelerating operation to switch from the first speed side to the second speed side, and a decelerating operation to switch from the second speed to the first speed.

The rotation speed detection device 68 is composed of a sensor or the like that detects the rotation speed, and is capable of detecting the prime mover rotation speed, which is the rotation speed of the prime mover 32 .
The control device 60 includes an automatic deceleration unit 61. The automatic deceleration unit 61 is an electric/electronic circuit or the like provided in the control device 60, a program or the like stored in the control device 60, or the like.
The automatic deceleration unit 61 performs automatic deceleration control when automatic deceleration is enabled, and does not perform automatic deceleration control when automatic deceleration is disabled.

In the automatic deceleration control, when the travel motors (left travel motor 36L, right travel motor 36R) are at the second speed and a predetermined condition (automatic deceleration condition) is satisfied, the travel motors (left travel motor 36L, right travel motor 36R) are automatically switched from the second speed to the first speed. In the automatic deceleration control, when the automatic deceleration condition is satisfied in a situation where at least the travel motors (left travel motor 36L, right travel motor 36R) are at the second speed, the control device 60 demagnetizes the solenoid of the second switching valve 72, thereby switching the second switching valve 72 from the second position 72b to the first position 72a, thereby decelerating the travel motors (left travel motor 36L, right travel motor 36R) from the second speed to the first speed.

That is, when performing automatic deceleration in the automatic deceleration control, the control device 60 decelerates both the left traveling motor 36L and the right traveling motor 36R from the second speed to the first speed.
When the automatic deceleration unit 61 satisfies the return condition after performing the automatic deceleration, the solenoid of the second switching valve 72 is excited to switch the second switching valve 72 from the first position 72a to the second position 72b, thereby increasing the speed of the travel motors (left travel motor 36L, right travel motor 36R) from the first speed to the second speed, i.e., returning the speed of the travel motors. In other words, when returning from the first speed to the second speed, the control device 60 increases the speed of both the left travel motor 36L and the right travel motor 36R from the first speed to the second speed.

When automatic deceleration is disabled, the control device 60 performs manual switching control to switch the travel motors (left travel motor 36L, right travel motor 36R) to either the first speed or the second speed in response to the operation of the speed change switch 67. In the manual switching control, when the speed change switch 67 is switched to the first speed side, the solenoid of the second changeover valve 72 is de-energized to set the travel motors (left travel motor 36L, right travel motor 36R) to the first speed.

In addition, in the manual switching control, when the speed changeover switch 67 is switched to the second speed side, the solenoid of the second changeover valve 72 is de-energized to set the travel motors (left travel motor 36L, right travel motor 36R) to the second speed.
Now, the hydraulic system of the work machine can determine the operation of the travel operating member 69 based on the pressure of the hydraulic oil acting on the travel oil passages 45 (first travel oil passage 45a, second travel oil passage 45b, third travel oil passage 45c, fourth travel oil passage 45d).

The determination of the operation of the travel operating member 69 will be described in detail below.
1, a first pressure detection device 48a capable of detecting a first pilot pressure lf, which is the pressure of the hydraulic oil in the first travel oil line 45a, is connected to the first travel oil line 45a. A second pressure detection device 48b capable of detecting a second pilot pressure lb, which is the pressure of the hydraulic oil in the second travel oil line 45b, is connected to the second travel oil line 45b.

A third pressure detection device 48c capable of detecting a third pilot pressure rf, which is the pressure of the hydraulic oil in the third travel oil line 45c, is connected to the third travel oil line 45c. A fourth pressure detection device 48d capable of detecting a fourth pilot pressure rb, which is the pressure of the hydraulic oil in the fourth travel oil line 45d, is connected to the fourth travel oil line 45d.
The first pressure detection device 48 a, the second pressure detection device 48 b, the third pressure detection device 48 b, and the fourth pressure detection device 48 d are connected to the control device 60.

In the travel oil passage 45, downstream of the first pressure detection device 48a, the second pressure detection device 48b, the third pressure detection device 48b and the fourth pressure detection device 48d, there are provided throttling sections 95a, 95b, 95c and 95d (referred to as the first throttling section 95a, the second throttling section 95b, the third throttling section 95c and the fourth throttling section 95d, respectively).
In detail, the throttling section 95a is provided in the first travel oil passage 45a, downstream of the first pressure detection device 48a (travel pump side), the throttling section 95b is provided in the second travel oil passage 45b, downstream of the second pressure detection device 48b (travel pump side), the throttling section 95c is provided in the third travel oil passage 45c, downstream of the third pressure detection device 48c (travel pump side), and the throttling section 95d is provided in the fourth travel oil passage 45d, downstream of the fourth pressure detection device 48d (travel pump side).

In other words, the first pressure detection device 48a, the second pressure detection device 48b, the third pressure detection device 48b, and the fourth pressure detection device 48d are located upstream (on the operating valve 55 side) of the throttling sections 95a, 95b, 95c, and 95d, respectively. Since the first pressure detection device 48a, the second pressure detection device 48b, the third pressure detection device 48b, and the fourth pressure detection device 48d are located upstream (on the pilot valve side) of these throttling sections 95a, 95b, 95c, and 95d, the operation of the operating device 54 is accurately detected.

The control device 60 determines the operation of the travel operating member 69 based on the first pilot pressure lf detected by the first pressure detection device 48a, the second pilot pressure lb detected by the second travel oil line 45b, the third pilot pressure rf detected by the third travel oil line 45c, and the fourth pilot pressure rb detected by the fourth travel oil line 45d.
In this embodiment, the first pilot pressure lf, the second pilot pressure lb, and the third pilot pressure r
f and the pressure of the fourth pilot pressure rb, it is determined whether the operation direction of the travel operating member 69 is the reverse side.

3 shows the relationship between the operation direction when the travel operation member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb. The arrows in Fig. 3 show the pilot pressures.
As shown in Fig. 3, when the travel operating member 59 is tilted forward, the first pilot pressure lf and the third pilot pressure rf increase. When the travel operating member 59 is tilted rearward, the second pilot pressure lb and the fourth pilot pressure rb increase. When the travel operating member 59 is tilted leftward, the second pilot pressure lb and the third pilot pressure rf increase. When the travel operating member 59 is tilted rightward, the first pilot pressure lf and the fourth pilot pressure rb increase.

When the travel operating member 59 is tilted diagonally forward to the left, the first pilot pressure lf, the second pilot pressure lb, and the third pilot pressure rf increase. When the travel operating member 59 is tilted diagonally forward to the right, the first pilot pressure lf, the third pilot pressure rf, and the fourth pilot pressure rb increase.
When the travel operating member 59 is tilted diagonally rearward to the left, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb increase. When the travel operating member 59 is tilted diagonally rearward to the right, the first pilot pressure lf, the second pilot pressure lb, and the fourth pilot pressure rb increase.

The control device 60 determines the operation direction of the travel operating member 59 based on either first comparison information including a comparison result between the first pilot pressure lf and the second pilot pressure lb corresponding to the left travel pump 53L, or second comparison information including a comparison result between the third pilot pressure rf and the fourth pilot pressure rb acting on the right travel pump 53R.
The comparison result included in the first comparison information is information obtained using calculations or functions such as the magnitude relationship (difference) between the first pilot pressure lf and the second pilot pressure lb, the ratio (ratio) of the second pilot pressure lb to the first pilot pressure lf, the ratio (ratio) of the first pilot pressure lf to the second pilot pressure lb, or the magnitude relationship (difference) between the first pilot pressure lf and the second pilot pressure lb with respect to a predetermined value, and is information that directly or indirectly indicates the magnitude relationship of the pilot pressures.

Like the first comparison information, the comparison result included in the second comparison information is information that directly or indirectly indicates the magnitude relationship between the third pilot pressure rf and the fourth pilot pressure rb.
Similarly to the first comparison information and the second comparison information, the operation direction of the travel operating member 59 can also be determined using third comparison information including the comparison result between the first pilot pressure lf and the fourth pilot pressure rb, and fourth comparison information including the comparison result between the second pilot pressure lb and the third pilot pressure rf.

The control device 60 determines that the operation direction of the travel operating member 59 is other than the reverse side when the first comparison information indicates that the first pilot pressure lf is greater than the second pilot pressure lb and the ratio of the second pilot pressure lb to the first pilot pressure lf is less than a first threshold value.
The control device 60 determines that the operation direction of the travel operating member 59 is other than the reverse side when the second comparison information indicates that the third pilot pressure rf is greater than the fourth pilot pressure rb and the ratio of the fourth pilot pressure rb to the third pilot pressure rf is less than the second threshold value.

FIG. 4 shows an operational flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the first comparison information and the second comparison information.
As shown in FIG. 4, the control device 60 refers to the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, and determines whether any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than an operating pressure α for determining whether or not the travel operating member 59 is being operated (step S1).

If none of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, No), it is determined that the travel operating member 59 has not been operated (step S2).
If any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, Yes), the control device 60 determines whether the first pilot pressure lf is greater than the second pilot pressure lb (step S3).

If the first pilot pressure lf is greater than the second pilot pressure lb (step S3, Yes), the control device 60 determines whether the ratio of the second pilot pressure lb to the first pilot pressure lf is less than a first threshold value β1 (step S4).
If the ratio of the second pilot pressure lb to the first pilot pressure lf is less than the first threshold value β1 (step S4, Yes), the control device 60 determines that the first condition is satisfied and turns on a first flag indicating that the first condition is satisfied (step S5).

In addition, if the first pilot pressure lf is not greater than the second pilot pressure lb (step S3, No), or if the ratio of the second pilot pressure lb to the first pilot pressure lf is not less than the first threshold value β1 (step S4, No), the control device 60 determines that the first condition is not satisfied and does not turn on the first flag.
In addition, the control device 60 determines whether the third pilot pressure rf is greater than the fourth pilot pressure rb (step S6).

If the third pilot pressure rf is greater than the fourth pilot pressure rb (step S6, Yes), the control device 60 determines whether the ratio of the fourth pilot pressure rb to the third pilot pressure rf is less than a second threshold value β2 (step S7).
If the ratio of the fourth pilot pressure rb to the third pilot pressure rf is less than the second threshold value β2 (step S7, Yes), the control device 60 determines that the second condition is satisfied and turns on a second flag indicating that the second condition is satisfied (step S8).

In addition, if the third pilot pressure rf is not greater than the fourth pilot pressure rb (step S6, No), or if the ratio of the fourth pilot pressure rb to the third pilot pressure rf is not less than the second threshold value β2 (step S7, No), the control device 60 determines that the second condition is not satisfied and does not turn on the second flag.
The control device 60 determines whether or not either the first condition or the second condition is satisfied (either the first flag or the second flag is ON) (step S9).

When either the first condition or the second condition is satisfied (step S9, Yes), the control device 60 determines that the operation direction of the travel operation member 59 is other than the reverse side (step S10).
If neither the first condition nor the second condition is satisfied (step S9, No), the control device 60 determines that the operation direction of the travel operation member 59 is the reverse side (step S11).

As shown in FIG. 3, the operation direction of the travel operating member 59 in the reverse direction corresponds to an area BA1, and the operation direction of the travel operating member 59 in a direction other than the reverse direction corresponds to an area FA1.
As described above, the control device 60 determines that the operation direction of the travel operating member 59 is other than the reverse side when the first pilot pressure lf is greater than the second pilot pressure lb and the ratio of the second pilot pressure lb to the first pilot pressure lf is less than the first threshold value β1, and can also determine that the operation direction of the travel operating member 59 is other than the reverse side when the third pilot pressure rf is greater than the fourth pilot pressure rb and the ratio of the fourth pilot pressure rb to the third pilot pressure rf is less than the second threshold value β2.

In other words, the control device 60 can determine, based on the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, whether the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the reverse side area BA1, or the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the area FA1 other than the reverse side.

Fig. 5 shows a hydraulic system (hydraulic circuit) of a work machine different from that shown in Fig. 1. Note that the hydraulic system of the work machine in Fig. 5 has a different connection between the travel operation device 54 and the travel pumps (left travel pump 53L, right travel pump 53R).
In Fig. 5, other configurations are the same as those in Fig. 1. In Fig. 5, the high pressure selection valves 47a, 47b, 47c, and 47d are not provided. The operation valve 55A is connected to the first travel oil passage 45a, the operation valve 55B is connected to the second travel oil passage 45b, the operation valve 55C is connected to the third travel oil passage 45c, and the operation valve 55D is connected to the fourth travel oil passage 45d.

FIG. 6 shows the relationship between the operating direction when the travel operating member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system in FIG. 5.
The arrows in Fig. 6 indicate the pilot pressures. As shown in Fig. 5, when the travel operating member 59 is tilted forward, the first pilot pressure lf and the third pilot pressure rf increase. When the travel operating member 59 is tilted rearward, the second pilot pressure lb and the fourth pilot pressure rb increase.

When the travel operating member 59 is tilted to the left, the second pilot pressure lb and the third pilot pressure rf increase, and when the travel operating member 59 is tilted to the right, the first pilot pressure lf and the fourth pilot pressure rb increase.
When the travel operating member 59 is tilted diagonally forward to the left, the third pilot pressure rf increases. When the travel operating member 59 is tilted diagonally forward to the right, the first pilot pressure lf increases. When the travel operating member 59 is tilted diagonally backward to the left, the second pilot pressure lb increases. When the travel operating member 59 is tilted diagonally backward to the right, the fourth pilot pressure rb increases.

FIG. 7 is a flow chart showing an operation flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the third comparison information and the fourth comparison information.
As shown in FIG. 7, the control device 60 refers to the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, and determines whether any of the referenced first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α that determines the operation (step S1).

If none of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, No), it is determined that the travel operating member 59 has not been operated (step S2).
If any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, Yes), the control device 60 determines whether the second pilot pressure lb is greater than the first pilot pressure lf (step S20).

If the second pilot pressure lb is greater than the first pilot pressure lf (step S20, Yes), the control device 60 determines whether the ratio of the third pilot pressure rf to the second pilot pressure lb is less than a third threshold value β3 (step S21).
If the ratio of the third pilot pressure rf to the second pilot pressure lb is less than the third threshold value β3 (step S21, Yes), the control device 60 determines that the third condition is satisfied and turns on a third flag indicating that the third condition is satisfied (step S22).

In addition, if the second pilot pressure lb is not greater than the first pilot pressure lf (step S20, No), or if the ratio of the third pilot pressure rf to the second pilot pressure lb is not less than the third threshold value β3 (step S21, No), the control device 60 determines that the third condition is not satisfied and does not turn on the third flag.
In addition, the control device 60 determines whether the fourth pilot pressure rb is greater than the third pilot pressure rf (step S23).

If the fourth pilot pressure rb is greater than the third pilot pressure rf (step S23, Yes), the control device 60 determines whether the ratio of the first pilot pressure lf to the fourth pilot pressure rb is less than a fourth threshold value β4 (step S24).
If the ratio of the first pilot pressure lf to the fourth pilot pressure rb is less than the fourth threshold value β4 (step S24, Yes), the control device 60 determines that the fourth condition is satisfied and turns on a fourth flag indicating that the fourth condition is satisfied (step S25).

In addition, if the fourth pilot pressure rb is not greater than the third pilot pressure rf (step S23, No), or if the ratio of the first pilot pressure lf to the fourth pilot pressure rb is not less than the fourth threshold value β4 (step S24, No), the control device 60 determines that the fourth condition is not satisfied and does not turn on the fourth flag.
The control device 60 determines whether or not either the third condition or the fourth condition is satisfied (either the third flag or the fourth flag is ON) (step S26).

If either the third condition or the fourth condition is satisfied (Yes in step S26), the control device 60 determines that the operation direction of the travel operation member 59 is the reverse side (step S27).
If neither the third condition nor the fourth condition is satisfied (step S26, No), the control device 60 determines that the operation direction of the travel operation member 59 is other than the reverse side (step S28).

As shown in FIG. 6, the operation direction of the travel operating member 59 in the reverse direction corresponds to an area BA1, and the operation direction of the travel operating member 59 in a direction other than the reverse direction corresponds to an area FA1.
The control device 60 determines that the operation direction of the travel operating member 59 is other than the reverse side when the second pilot pressure lb is greater than the first pilot pressure lf and the ratio of the third pilot pressure rf to the second pilot pressure lb is less than a third threshold value β3, and determines that the operation direction of the travel operating member 59 is other than the reverse side when the fourth pilot pressure rb is greater than the third pilot pressure rf and the ratio of the first pilot pressure lf to the fourth pilot pressure rb is less than a fourth threshold value β4.

In other words, the control device 60 can determine from the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb whether the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the reverse side area BA1, or the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the area FA1 other than the reverse side.

The work machine 1 includes a machine body 2, a left running device 5L provided on the left side of the machine body 2, a right running device 5R provided on the right side of the machine body 2, a left running motor 36L capable of transmitting power to the left running device 5L, a right running motor 36R capable of transmitting power to the right running device 5R, a left running pump 53L having a first pressure receiving portion 53a and a second pressure receiving portion 53b that receive hydraulic oil and supplying hydraulic oil to the left running motor 36L when hydraulic oil acts on at least either the first pressure receiving portion 53a or the second pressure receiving portion 53b, and a third pressure receiving portion 53a and a fourth pressure receiving portion 53b that receive hydraulic oil and at least a right travel pump 53R that supplies hydraulic oil to the right travel motor 36R when hydraulic oil acts on at least one of the third pressure receiving portion 53a and the fourth pressure receiving portion 53b; a travel operation device 54 that applies hydraulic oil to at least one of the first pressure receiving portion 53a, the second pressure receiving portion 53b, the third pressure receiving portion 53a, and the fourth pressure receiving portion 53b when the travel operation member 59 is operated; a first travel oil passage 45a that is connected to the first pressure receiving portion 53a and that passes hydraulic oil that acts on the first pressure receiving portion 53a when the travel operation member 59 is operated; a second travel oil passage 45b for passing hydraulic oil acting on the second pressure receiving portion 53b when the travel operating member 59 is operated; a third travel oil passage 45c connected to the third pressure receiving portion 53a and for passing hydraulic oil acting on the third pressure receiving portion 53a when the travel operating member 59 is operated; a fourth travel oil passage 45d connected to the fourth pressure receiving portion 53b and for passing hydraulic oil acting on the fourth pressure receiving portion 53b when the travel operating member 59 is operated; a first pressure detection device 48a capable of detecting a first pilot pressure which is the pressure of the hydraulic oil in the first travel oil passage 45a; and a second pressure detection device 49a capable of detecting a second pilot pressure which is the pressure of the hydraulic oil in the second travel oil passage 45b. It is equipped with a force detection device 48b, a third pressure detection device 48c capable of detecting a third pilot pressure, which is the pressure of the hydraulic oil in the third travel oil line 45c, a fourth pressure detection device 48d capable of detecting a fourth pilot pressure, which is the pressure of the hydraulic oil in the fourth travel oil line 45d, and a control device 60 that determines the operation direction of the travel operation member 59 based on either first comparison information including a comparison between the first pilot pressure and the second pilot pressure acting on the left travel pump 53L or second comparison information including a comparison between the third pilot pressure and the fourth pilot pressure acting on the left travel pump 53L.

According to this, by comparing the first pilot pressure and the second pilot pressure acting on the left traveling pump 53L and the third pilot pressure and the fourth pilot pressure acting on the right traveling pump 53L, the operation direction of the traveling operating member 59 can be easily determined without using a sensor such as a potentiometer.
The control device 60 determines that the operation direction of the travel operating member 59 is other than the reverse side when the first comparison information indicates that the first pilot pressure is greater than the second pilot pressure and the ratio of the second pilot pressure to the first pilot pressure is less than a first threshold value.

According to this, it is possible to easily grasp, based on the pilot pressure alone, that the operating member 59 has been operated to a side other than the reverse side.
The control device 60 determines that the operation direction of the travel operating member 59 is other than the reverse side when the second comparison information indicates that the third pilot pressure is greater than the fourth pilot pressure and the ratio of the fourth pilot pressure to the third pilot pressure is less than the second threshold value.

According to this, it is possible to easily grasp, based on the pilot pressure alone, that the operating member 59 has been operated to a side other than the reverse side.
The control device 60 determines that the operation direction of the travel operating member 59 is reverse when the first comparison information indicates that the second pilot pressure is greater than the first pilot pressure and the ratio of the third pilot pressure to the second pilot pressure is less than a third threshold value.

According to this, it is possible to easily grasp that the operating member 59 has been operated to the reverse side by only the pilot pressure.
The control device 60 determines that the operation direction of the travel operating member 59 is reverse when the second comparison information indicates that the fourth pilot pressure is greater than the third pilot pressure and the ratio of the first pilot pressure to the fourth pilot pressure is less than a fourth threshold value.

According to this, it is possible to easily grasp that the operating member 59 has been operated to the reverse side by only the pilot pressure.
The control device 60 determines the operation direction of the travel operating member 59 based on whether either the first pilot pressure or the second pilot pressure is above a predetermined value, or whether both the first pilot pressure and the second pilot pressure are above a predetermined value.

The control device 60 determines the operation direction of the travel operating member 59 based on whether either the third pilot pressure or the fourth pilot pressure is above a predetermined value, or whether both the third pilot pressure and the fourth pilot pressure are above a predetermined value.
Second Embodiment
A second embodiment of the present invention will be described with reference to Figures 8 to 11. In this embodiment, in the hydraulic system shown in Figure 1 and the hydraulic system shown in Figure 5 described in the first embodiment, the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb are used to determine whether the operation direction of the travel operating member 69 is the forward direction.

In this embodiment, the same reference numerals are used for the configurations described in the first embodiment, and detailed description thereof will be omitted.
Fig. 8 is a diagram showing the relationship between the operation direction when the travel operating member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in Fig. 1. The arrows in Fig. 8 indicate the pilot pressures. Fig. 9 is a diagram showing an operation flow in which the control device 60 determines the operation direction of the travel operating member 59 based on the first comparison information and the second comparison information.

Figure 10 is a diagram showing the relationship between the operation direction when the travel operation member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in Figure 5. The arrows in Figure 10 indicate the pilot pressures. Figure 11 is a diagram showing the operation flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the third comparison information and the fourth comparison information.

As shown in FIG. 8, when the travel operating member 59 is tilted forward, the first pilot pressure lf and the third pilot pressure rf increase. When the travel operating member 59 is tilted rearward, the second pilot pressure lb and the fourth pilot pressure rb increase. When the travel operating member 59 is tilted leftward, the second pilot pressure lb and the third pilot pressure rf increase. When the travel operating member 59 is tilted rightward, the first pilot pressure lf and the fourth pilot pressure rb increase.

When the travel operating member 59 is tilted diagonally forward to the left, the first pilot pressure lf, the second pilot pressure lb, and the third pilot pressure rf increase. When the travel operating member 59 is tilted diagonally forward to the right, the first pilot pressure lf, the third pilot pressure rf, and the fourth pilot pressure rb increase.
When the travel operating member 59 is tilted diagonally rearward to the left, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb increase. When the travel operating member 59 is tilted diagonally rearward to the right, the first pilot pressure lf, the second pilot pressure lb, and the fourth pilot pressure rb increase.

The control device 60 determines the operation direction of the travel operating member 59 based on either first comparison information including a comparison result between the first pilot pressure lf and the second pilot pressure lb corresponding to the left travel pump 53L, or second comparison information including a comparison result between the third pilot pressure rf and the fourth pilot pressure rb acting on the right travel pump 53R.
The comparison result included in the first comparison information is information obtained using calculations or functions such as the magnitude relationship (difference) between the first pilot pressure lf and the second pilot pressure lb, the ratio (ratio) of the second pilot pressure lb to the first pilot pressure lf, the ratio (ratio) of the first pilot pressure lf to the second pilot pressure lb, or the magnitude relationship (difference) between the first pilot pressure lf and the second pilot pressure lb with respect to a predetermined value, and is information that directly or indirectly indicates the magnitude relationship of the pilot pressures.

Like the first comparison information, the comparison result included in the second comparison information is information that directly or indirectly indicates the magnitude relationship between the third pilot pressure rf and the fourth pilot pressure rb.
Similarly to the first comparison information and the second comparison information, the operation direction of the travel operating member 59 can also be determined using third comparison information including the comparison result between the first pilot pressure lf and the fourth pilot pressure rb, and fourth comparison information including the comparison result between the second pilot pressure lb and the third pilot pressure rf.

The control device 60 determines that the operation direction of the travel operating member 59 is other than the forward direction when the first comparison information indicates that the second pilot pressure lb is greater than the first pilot pressure lf and the ratio of the first pilot pressure lf to the second pilot pressure lb is less than a first threshold value.
The control device 60 determines that the operation direction of the travel operating member 59 is other than the forward direction when the second comparison information indicates that the fourth pilot pressure rb is greater than the third pilot pressure rf and the ratio of the third pilot pressure rf to the fourth pilot pressure rb is less than the second threshold value.

FIG. 9 is a flow chart showing an operation flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the first comparison information and the second comparison information.
As shown in FIG. 9, the control device 60 refers to the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, and determines whether any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α for determining whether or not the travel operating member 59 is being operated (step S1).

If none of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, No), it is determined that the travel operating member 59 has not been operated (step S2).
If any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, Yes), the control device 60 determines whether the second pilot pressure lb is greater than the first pilot pressure lf (step S3).

If the second pilot pressure lb is greater than the first pilot pressure lf (step S3, Yes), the control device 60 determines whether the ratio of the first pilot pressure lf to the second pilot pressure lb is less than a first threshold value β1 (step S4).
If the ratio of the first pilot pressure lf to the second pilot pressure lb is less than the first threshold value β1 (step S4, Yes), the control device 60 determines that the first condition is satisfied and turns on a first flag indicating that the first condition is satisfied (step S5).

In addition, if the second pilot pressure lb is not greater than the first pilot pressure lf (step S3, No), or if the ratio of the first pilot pressure lf to the second pilot pressure lb is not less than the first threshold value β1 (step S4, No), the control device 60 determines that the first condition is not satisfied and does not turn the first flag ON.
In addition, the control device 60 determines whether the fourth pilot pressure rb is greater than the third pilot pressure rf (step S6).

If the fourth pilot pressure rb is greater than the third pilot pressure rf (step S6, Yes), the control device 60 determines whether the ratio of the third pilot pressure rf to the fourth pilot pressure rb is less than a second threshold value β2 (step S7).
If the ratio of the third pilot pressure rf to the fourth pilot pressure rb is less than the second threshold value β2 (step S7, Yes), the control device 60 determines that the second condition is satisfied and turns on the second flag indicating that the second condition is satisfied (step S8).

In addition, if the fourth pilot pressure rb is not greater than the third pilot pressure rf (step S6, No), or if the ratio of the third pilot pressure rf to the fourth pilot pressure rb is not less than the second threshold value β2 (step S7, No), the control device 60 determines that the second condition is not satisfied and does not turn the second flag ON.
The control device 60 determines whether or not either the first condition or the second condition is satisfied (either the first flag or the second flag is ON) (step S9).

When either the first condition or the second condition is satisfied (step S9, Yes), the control device 60 determines that the operation direction of the travel operation member 59 is other than the forward direction (step S10).
If neither the first condition nor the second condition is satisfied (step S9, No), the control device 60 determines that the operation direction of the travel operation member 59 is the forward direction (step S11).

As shown in FIG. 8, the forward direction of the operation of the travel operating member 59 corresponds to the area FA2, and the other direction of the operation of the travel operating member 59 corresponds to the area BA2.
As described above, the control device 60 determines that the operation direction of the travel operating member 59 is other than the forward direction when the second pilot pressure lb is greater than the first pilot pressure lf and the ratio of the first pilot pressure lf to the second pilot pressure lb is less than the first threshold value β1. Furthermore, the control device 60 also determines that the operation direction of the travel operating member 59 is other than the forward direction when the fourth pilot pressure rb is greater than the third pilot pressure rf and the ratio of the third pilot pressure rf to the fourth pilot pressure rb is less than the second threshold value β2.

In other words, based on the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, the control device 60 can determine whether the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the forward direction area FA2, or whether the operation direction of the travel operating member 59 is in the area BA2 other than the forward direction.

FIG. 10 shows the relationship between the operating direction when the travel operating member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system in FIG. 5.
The arrows in Fig. 10 indicate the pilot pressures. As shown in Fig. 10, when the travel operating member 59 is tilted forward, the first pilot pressure lf and the third pilot pressure rf increase. When the travel operating member 59 is tilted rearward, the second pilot pressure lb and the fourth pilot pressure rb increase.

When the travel operating member 59 is tilted to the left, the second pilot pressure lb and the third pilot pressure rf increase, and when the travel operating member 59 is tilted to the right, the first pilot pressure lf and the fourth pilot pressure rb increase.
When the travel operating member 59 is tilted diagonally forward to the left, the third pilot pressure rf increases. When the travel operating member 59 is tilted diagonally forward to the right, the first pilot pressure lf increases. When the travel operating member 59 is tilted diagonally backward to the left, the second pilot pressure lb increases. When the travel operating member 59 is tilted diagonally backward to the right, the fourth pilot pressure rb increases.

FIG. 11 is a flow chart showing an operation of the control device 60 determining the operation direction of the travel operation member 59 based on the third comparison information and the fourth comparison information.
As shown in FIG. 11, the control device 60 refers to the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, and determines whether any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α for determining whether or not the travel operating member 59 is being operated (step S1).

If none of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, No), it is determined that the travel operating member 59 has not been operated (step S2).
If any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, Yes), the control device 60 determines whether the first pilot pressure lf is greater than the second pilot pressure lb (step S20).

If the first pilot pressure lf is greater than the second pilot pressure lb (step S20, Yes), the control device 60 determines whether the ratio of the fourth pilot pressure rb to the first pilot pressure lf is less than a third threshold value β3 (step S21).
If the ratio of the fourth pilot pressure rb to the first pilot pressure lf is less than the third threshold value β3 (step S21, Yes), the control device 60 determines that the third condition is satisfied and turns ON a third flag indicating that the third condition is satisfied (step S22).

In addition, if the first pilot pressure lf is not greater than the second pilot pressure lb (step S20, No), or if the ratio of the fourth pilot pressure rb to the first pilot pressure lf is not less than the third threshold value β3 (step S21, No), the control device 60 determines that the third condition is not satisfied and does not turn the third flag ON.
In addition, the control device 60 determines whether the third pilot pressure rf is greater than the fourth pilot pressure rb (step S23).

If the third pilot pressure rf is greater than the fourth pilot pressure rb (step S23, Yes), the control device 60 determines whether the ratio of the second pilot pressure lb to the third pilot pressure rf is less than a fourth threshold value β4 (step S24).
If the ratio of the second pilot pressure lb to the third pilot pressure rf is less than the fourth threshold value β4 (step S24, Yes), the control device 60 determines that the fourth condition is satisfied and turns on the fourth flag indicating that the fourth condition is satisfied (step S25).

In addition, if the third pilot pressure rf is not greater than the fourth pilot pressure rb (step S23, No), or if the ratio of the second pilot pressure lb to the third pilot pressure rf is not less than the fourth threshold value β4 (step S24, No), the control device 60 determines that the fourth condition is not satisfied and does not turn the fourth flag ON.
The control device 60 determines whether or not either the third condition or the fourth condition is satisfied (either the third flag or the fourth flag is ON) (step S26).

When either the third condition or the fourth condition is satisfied (step S26, Yes), the control device 60 determines that the operation direction of the travel operation member 59 is the forward direction (step S27).
If neither the third condition nor the fourth condition is satisfied (step S26, No), the control device 60 determines that the operation direction of the travel operation member 59 is other than the forward direction (step S28).

As shown in FIG. 10, the reverse side in the operation direction of the travel operating member 59 corresponds to the area FA2, and the other side in the operation direction of the travel operating member 59 corresponds to the area BA2.
The control device 60 determines that the operation direction of the travel operating member 59 is the forward side when the first pilot pressure lf is greater than the second pilot pressure lb and the ratio of the fourth pilot pressure rb to the first pilot pressure lf is less than a third threshold value β3, and determines that the operation direction of the travel operating member 59 is the forward side when the third pilot pressure rf is greater than the fourth pilot pressure rb and the ratio of the second pilot pressure lb to the third pilot pressure rf is less than a fourth threshold value β4.

In other words, the control device 60 can determine from the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb whether the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the forward direction area FA2, or the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the forward direction area BA2 other than the forward direction.
According to this embodiment, as in the first embodiment, by comparing the first pilot pressure and the second pilot pressure acting on the left traveling pump 53L and the third pilot pressure and the fourth pilot pressure acting on the right traveling pump 53L, the operation direction of the traveling operating member 59 can be easily determined without using a sensor such as a potentiometer.

In addition, it is possible to easily determine, based on the pilot pressure alone, whether the operating member 59 has been operated to a direction other than the forward movement side or whether the operating member 59 has been operated to the forward movement side.
Third Embodiment
A third embodiment of the present invention will be described with reference to Figures 12 to 17. In this embodiment, in the hydraulic system shown in Figure 1 and the hydraulic system shown in Figure 5 described in the first embodiment, the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb are used to determine whether the operation direction of the travel operating member 69 is the left turning side or the right turning side.

In this embodiment, the same reference numerals are used for the configurations described in the first embodiment, and detailed description thereof will be omitted.
First, a configuration for determining whether or not the operation direction of the travel operation member 69 is the left turning side will be described.
Fig. 12 is a diagram showing the relationship between the operation direction when the travel operating member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in Fig. 1. The arrows in Fig. 12 indicate the pilot pressures. Fig. 13 is a diagram showing an operation flow in which the control device 60 determines the operation direction of the travel operating member 59 based on the first comparison information and the second comparison information.

Figure 14 is a diagram showing the relationship between the operation direction when the travel operation member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in Figure 5. The arrows in Figure 14 indicate the pilot pressures. Figure 15 is a diagram showing the operation flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the third comparison information and the fourth comparison information.

As shown in FIG. 12, when the travel operating member 59 is tilted forward, the first pilot pressure lf and the third pilot pressure rf increase. When the travel operating member 59 is tilted rearward, the second pilot pressure lb and the fourth pilot pressure rb increase. When the travel operating member 59 is tilted leftward, the second pilot pressure lb and the third pilot pressure rf increase. When the travel operating member 59 is tilted rightward, the first pilot pressure lf and the fourth pilot pressure rb increase.

When the travel operating member 59 is tilted diagonally forward to the left, the first pilot pressure lf, the second pilot pressure lb, and the third pilot pressure rf increase. When the travel operating member 59 is tilted diagonally forward to the right, the first pilot pressure lf, the third pilot pressure rf, and the fourth pilot pressure rb increase.
When the travel operating member 59 is tilted diagonally rearward to the left, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb increase. When the travel operating member 59 is tilted diagonally rearward to the right, the first pilot pressure lf, the second pilot pressure lb, and the fourth pilot pressure rb increase.

The control device 60 determines the operation direction of the travel operating member 59 based on either first comparison information including a comparison result between the first pilot pressure lf and the second pilot pressure lb corresponding to the left travel pump 53L, or second comparison information including a comparison result between the third pilot pressure rf and the fourth pilot pressure rb acting on the right travel pump 53R.
The comparison result included in the first comparison information is information obtained using calculations or functions such as the magnitude relationship (difference) between the first pilot pressure lf and the second pilot pressure lb, the ratio (ratio) of the second pilot pressure lb to the first pilot pressure lf, the ratio (ratio) of the first pilot pressure lf to the second pilot pressure lb, or the magnitude relationship (difference) between the first pilot pressure lf and the second pilot pressure lb with respect to a predetermined value, and is information that directly or indirectly indicates the magnitude relationship of the pilot pressures.

Like the first comparison information, the comparison result included in the second comparison information is information that directly or indirectly indicates the magnitude relationship between the third pilot pressure rf and the fourth pilot pressure rb.
Similarly to the first comparison information and the second comparison information, the operation direction of the travel operating member 59 can also be determined using third comparison information including the comparison result between the first pilot pressure lf and the fourth pilot pressure rb, and fourth comparison information including the comparison result between the second pilot pressure lb and the third pilot pressure rf.

The control device 60 determines that the operation direction of the travel operating member 59 is other than a left turn when the first comparison information indicates that the first pilot pressure lf is greater than the second pilot pressure lb and the ratio of the second pilot pressure lb to the first pilot pressure lf is less than a first threshold value.
The control device 60 determines that the operation direction of the travel operating member 59 is other than a left turn when the second comparison information indicates that the fourth pilot pressure rb is greater than the third pilot pressure rf and the ratio of the third pilot pressure rf to the fourth pilot pressure rb is less than a second threshold value.

FIG. 13 is a flow chart showing an operation flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the first comparison information and the second comparison information.
As shown in FIG. 13, the control device 60 refers to the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, and determines whether any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α for determining whether or not the travel operating member 59 is being operated (step S1).

If none of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, No), it is determined that the travel operating member 59 has not been operated (step S2).
If any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, Yes), the control device 60 determines whether the first pilot pressure lf is greater than the second pilot pressure lb (step S3).

If the first pilot pressure lf is greater than the second pilot pressure lb (step S3, Yes), the control device 60 determines whether the ratio of the second pilot pressure lb to the first pilot pressure lf is less than a first threshold value β1 (step S4).
If the ratio of the second pilot pressure lb to the first pilot pressure lf is less than the first threshold value β1 (step S4, Yes), the control device 60 determines that the first condition is satisfied and turns on a first flag indicating that the first condition is satisfied (step S5).

In addition, if the first pilot pressure lf is not greater than the second pilot pressure lb (step S3, No), or if the ratio of the second pilot pressure lb to the first pilot pressure lf is not less than the first threshold value β1 (step S4, No), the control device 60 determines that the first condition is not satisfied and does not turn the first flag ON.
In addition, the control device 60 determines whether the fourth pilot pressure rb is greater than the third pilot pressure rf (step S6).

If the fourth pilot pressure rb is greater than the third pilot pressure rf (step S6, Yes), the control device 60 determines whether the ratio of the third pilot pressure rf to the fourth pilot pressure rb is less than a second threshold value β2 (step S7).
If the ratio of the third pilot pressure rf to the fourth pilot pressure rb is less than the second threshold value β2 (step S7, Yes), the control device 60 determines that the second condition is satisfied and turns on the second flag indicating that the second condition is satisfied (step S8).

In addition, if the fourth pilot pressure rb is not greater than the third pilot pressure rf (step S6, No), or if the ratio of the third pilot pressure rf to the fourth pilot pressure rb is not less than the second threshold value β2 (step S7, No), the control device 60 determines that the second condition is not satisfied and does not turn the second flag ON.
The control device 60 determines whether or not either the first condition or the second condition is satisfied (either the first flag or the second flag is ON) (step S9).

When either the first condition or the second condition is satisfied (step S9, Yes), the control device 60 determines that the operation direction of the travel operation member 59 is other than left turning (step S10).
When neither the first condition nor the second condition is satisfied (step S9, No), the control device 60 determines that the operation direction of the travel operation member 59 is the left turning side (step S11).

As shown in FIG. 12, the left turning side of the operation direction of the travel operating member 59 corresponds to area LA1, and the operation directions of the travel operating member 59 other than left turning correspond to area FA3, area RA1, or area BA3.
As described above, the control device 60 determines that the operation direction of the travel operating member 59 is other than a left turn when the first pilot pressure lf is greater than the second pilot pressure lb and the ratio of the first pilot pressure lf to the second pilot pressure lb is less than the first threshold value β1. Furthermore, the control device 60 also determines that the operation direction of the travel operating member 59 is other than a left turn when the fourth pilot pressure rb is greater than the third pilot pressure rf and the ratio of the third pilot pressure rf to the fourth pilot pressure rb is less than the second threshold value β2.

In other words, the control device 60 can determine, based on the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, whether the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the area LA1, which is the left turn side, or the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the area FA3, area RA1, or area BA3 other than the left turn.

FIG. 14 shows the relationship between the operating direction when the travel operating member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system in FIG. 5.
The arrows in Fig. 14 indicate the pilot pressures. As shown in Fig. 14, when the travel operating member 59 is tilted forward, the first pilot pressure lf and the third pilot pressure rf increase. When the travel operating member 59 is tilted rearward, the second pilot pressure lb and the fourth pilot pressure rb increase.

When the travel operating member 59 is tilted to the left, the second pilot pressure lb and the third pilot pressure rf increase, and when the travel operating member 59 is tilted to the right, the first pilot pressure lf and the fourth pilot pressure rb increase.
When the travel operating member 59 is tilted diagonally forward to the left, the third pilot pressure rf increases. When the travel operating member 59 is tilted diagonally forward to the right, the first pilot pressure lf increases. When the travel operating member 59 is tilted diagonally backward to the left, the second pilot pressure lb increases. When the travel operating member 59 is tilted diagonally backward to the right, the fourth pilot pressure rb increases.

FIG. 15 is an operational flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the third comparison information and the fourth comparison information.
As shown in FIG. 15, the control device 60 refers to the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, and determines whether any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α for determining whether or not the travel operating member 59 is being operated (step S1).

If none of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, No), it is determined that the travel operating member 59 has not been operated (step S2).
If any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, Yes), the control device 60 determines whether the second pilot pressure lb is greater than the first pilot pressure lf (step S20).

If the second pilot pressure lb is greater than the first pilot pressure lf (step S20, Yes), the control device 60 determines whether the ratio of the fourth pilot pressure rb to the second pilot pressure lb is less than a third threshold value β3 (step S21).
If the ratio of the fourth pilot pressure rb to the second pilot pressure lb is less than the third threshold value β3 (step S21, Yes), the control device 60 determines that the third condition is satisfied and turns on a third flag indicating that the third condition is satisfied (step S22).

In addition, if the second pilot pressure lb is not greater than the first pilot pressure lf (step S20, No), or if the ratio of the fourth pilot pressure rb to the second pilot pressure lb is not less than the third threshold value β3 (step S21, No), the control device 60 determines that the third condition is not satisfied and does not turn the third flag ON.
In addition, the control device 60 determines whether the third pilot pressure rf is greater than the fourth pilot pressure rb (step S23).

If the third pilot pressure rf is greater than the fourth pilot pressure rb (step S23, Yes), the control device 60 determines whether the ratio of the first pilot pressure lf to the third pilot pressure rf is less than a fourth threshold value β4 (step S24).
If the ratio of the first pilot pressure lf to the third pilot pressure rf is less than the fourth threshold value β4 (step S24, Yes), the control device 60 determines that the fourth condition is satisfied and turns on the fourth flag indicating that the fourth condition is satisfied (step S25).

In addition, if the third pilot pressure rf is not greater than the fourth pilot pressure rb (step S23, No), or if the ratio of the first pilot pressure lf to the third pilot pressure rf is not less than the fourth threshold value β4 (step S24, No), the control device 60 determines that the fourth condition is not satisfied and does not turn the fourth flag ON.
The control device 60 determines whether or not either the third condition or the fourth condition is satisfied (either the third flag or the fourth flag is ON) (step S26).

When either the third condition or the fourth condition is satisfied (step S26, Yes), the control device 60 determines that the operation direction of the travel operation member 59 is the left turning side (step S27).
If neither the third condition nor the fourth condition is satisfied (step S26, No), the control device 60 determines that the operation direction of the travel operation member 59 is other than the left turning side (step S28).

As shown in FIG. 14, the left turning side in the operation direction of the travel operating member 59 corresponds to area LA1, and the other sides in the operation direction of the travel operating member 59 correspond to areas FA3, RA1, and BA3.
The control device 60 determines that the operation direction of the travel operating member 59 is to the left turning side when the second pilot pressure lb is greater than the first pilot pressure lf and the ratio of the fourth pilot pressure rb to the second pilot pressure lb is less than a third threshold value β3, and determines that the operation direction of the travel operating member 59 is to the left turning side when the third pilot pressure rf is greater than the fourth pilot pressure rb and the ratio of the first pilot pressure lf to the third pilot pressure rf is less than a fourth threshold value β4.

In other words, the control device 60 can determine from the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb whether the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the area LA1, which is the left turning side, or the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the area FA3, area RA1, or area BA3 other than the left turning side.

According to this embodiment, as in the first embodiment, by comparing the first pilot pressure and the second pilot pressure acting on the left traveling pump 53L and the third pilot pressure and the fourth pilot pressure acting on the right traveling pump 53L, the operation direction of the traveling operating member 59 can be easily determined without using a sensor such as a potentiometer.
In addition, it is possible to easily determine, based on the pilot pressure alone, whether the operating member 59 has been operated to a side other than the left turning side or whether the operating member 59 has been operated to the left turning side.

Next, a configuration for determining whether the operation direction of the travel operation member 69 is the right turning side will be described with reference to Figures 12, 14, 16, and 17. Figure 16 is a diagram showing an operation flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the first comparison information and the second comparison information. Figure 17 is a diagram showing an operation flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the third comparison information and the fourth comparison information.

Fig. 12 is a diagram showing the relationship between the operation direction when the travel operation member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in Fig. 1. The relationship shown in Fig. 12 is as described above.
Fig. 14 is a diagram showing the relationship between the operation direction when the travel operation member 59 is operated and the pressures of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb in the hydraulic system shown in Fig. 5. The relationship shown in Fig. 14 is as described above.

The control device 60 determines the operation direction of the travel operation member 59 by using the first comparison information, the second comparison information, the third comparison information, and the fourth comparison information, in the same manner as in determining a right turn.
The control device 60 determines that the operation direction of the travel operating member 59 is other than a right turn when the first comparison information indicates that the second pilot pressure lb is greater than the first pilot pressure lf and the ratio of the first pilot pressure lf to the second pilot pressure lb is less than a first threshold value.

The control device 60 determines that the operation direction of the travel operating member 59 is other than a right turn when the second comparison information indicates that the third pilot pressure rf is greater than the fourth pilot pressure rb and the ratio of the fourth pilot pressure rb to the third pilot pressure rf is less than a second threshold value.
FIG. 16 shows an operational flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the first comparison information and the second comparison information.

As shown in FIG. 16, the control device 60 refers to the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, and determines whether any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α for determining whether the travel operating member 59 is being operated (step S1).

If none of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, No), it is determined that the travel operating member 59 has not been operated (step S2).
If any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, Yes), the control device 60 determines whether the second pilot pressure lb is greater than the first pilot pressure lf (step S3).

If the second pilot pressure lb is greater than the first pilot pressure lf (step S3, Yes), the control device 60 determines whether the ratio of the first pilot pressure lf to the second pilot pressure lb is less than a first threshold value β1 (step S4).
If the ratio of the first pilot pressure lf to the second pilot pressure lb is less than the first threshold value β1 (step S4, Yes), the control device 60 determines that the first condition is satisfied and turns on a first flag indicating that the first condition is satisfied (step S5).

In addition, if the second pilot pressure lb is not greater than the first pilot pressure lf (step S3, No), or if the ratio of the first pilot pressure lf to the second pilot pressure lb is not less than the first threshold value β1 (step S4, No), the control device 60 determines that the first condition is not satisfied and does not turn the first flag ON.
In addition, the control device 60 determines whether the third pilot pressure rf is greater than the fourth pilot pressure rb (step S6).

When the third pilot pressure rf is greater than the fourth pilot pressure rb (step S6, Ye
s), the control device 60 determines whether the ratio of the fourth pilot pressure rb to the third pilot pressure rf is less than a second threshold value β2 (step S7).
If the ratio of the fourth pilot pressure rb to the third pilot pressure rf is less than the second threshold value β2 (step S7, Yes), the control device 60 determines that the second condition is satisfied and turns on the second flag indicating that the second condition is satisfied (step S8).

In addition, if the third pilot pressure rf is not greater than the fourth pilot pressure rb (step S6, No), or if the ratio of the fourth pilot pressure rb to the third pilot pressure rf is not less than the second threshold value β2 (step S7, No), the control device 60 determines that the second condition is not satisfied and does not turn the second flag ON.
The control device 60 determines whether or not either the first condition or the second condition is satisfied (either the first flag or the second flag is ON) (step S9).

When either the first condition or the second condition is satisfied (step S9, Yes), the control device 60 determines that the operation direction of the travel operation member 59 is other than a right turn (step S10).
When neither the first condition nor the second condition is satisfied (step S9, No), the control device 60 determines that the operation direction of the travel operation member 59 is the right turning side (step S11).

As shown in FIG. 12, the right turning side in the operation direction of the travel operating member 59 corresponds to area RA1, and the operation directions of the travel operating member 59 other than right turning correspond to area FA3, area LA1, or area BA3.
As described above, the control device 60 determines that the operation direction of the travel operating member 59 is other than a right turn when the second pilot pressure lb is greater than the first pilot pressure lf and the ratio of the first pilot pressure lf to the second pilot pressure lb is less than the first threshold value β1. Furthermore, the control device 60 also determines that the operation direction of the travel operating member 59 is other than a right turn when the third pilot pressure rf is greater than the fourth pilot pressure rb and the ratio of the fourth pilot pressure rb to the third pilot pressure rf is less than the second threshold value β2.

In other words, based on the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, the control device 60 can determine the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in area RA1, which is the right turn side, or the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in area FA3, area LA1, or area BA3 other than the right turn.

FIG. 17 is an operational flow in which the control device 60 determines the operation direction of the travel operation member 59 based on the third comparison information and the fourth comparison information.
As shown in FIG. 17, the control device 60 refers to the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb, and determines whether any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α for determining whether or not the travel operating member 59 is being operated (step S1).

If none of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, No), it is determined that the travel operating member 59 has not been operated (step S2).
If any of the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb is greater than the operating pressure α (step S1, Yes), the control device 60 determines whether the first pilot pressure lf is greater than the second pilot pressure lb (step S20).

If the first pilot pressure lf is greater than the second pilot pressure lb (step S20, Yes), the control device 60 determines whether the ratio of the third pilot pressure rf to the first pilot pressure lf is less than a third threshold value β3 (step S21).
If the ratio of the third pilot pressure rf to the first pilot pressure lf is less than the third threshold value β3 (step S21, Yes), the control device 60 determines that the third condition is satisfied and turns on a third flag indicating that the third condition is satisfied (step S22).

In addition, if the first pilot pressure lf is not greater than the second pilot pressure lb (step S20, No), or if the ratio of the third pilot pressure rf to the first pilot pressure lf is not less than the third threshold value β3 (step S21, No), the control device 60 determines that the third condition is not satisfied and does not turn the third flag ON.
In addition, the control device 60 determines whether the fourth pilot pressure rb is greater than the third pilot pressure rf (step S23).

If the fourth pilot pressure rb is greater than the third pilot pressure rf (step S23, Yes), the control device 60 determines whether the ratio of the second pilot pressure lb to the fourth pilot pressure rb is less than a fourth threshold value β4 (step S24).
If the ratio of the second pilot pressure lb to the fourth pilot pressure rb is less than the fourth threshold value β4 (step S24, Yes), the control device 60 determines that the fourth condition is satisfied and turns on the fourth flag indicating that the fourth condition is satisfied (step S25).

In addition, if the fourth pilot pressure rb is not greater than the third pilot pressure rf (step S23, No), or if the ratio of the second pilot pressure lb to the fourth pilot pressure rb is not less than the fourth threshold value β4 (step S24, No), the control device 60 determines that the fourth condition is not satisfied and does not turn the fourth flag ON.
The control device 60 determines whether or not either the third condition or the fourth condition is satisfied (either the third flag or the fourth flag is ON) (step S26).

When either the third condition or the fourth condition is satisfied (step S26, Yes), the control device 60 determines that the operation direction of the travel operation member 59 is the right turning side (step S27).
If neither the third condition nor the fourth condition is satisfied (step S26, No), the control device 60 determines that the operation direction of the travel operation member 59 is other than the right turning side (step S28).

As shown in FIG. 14, the right turning side in the operation direction of the travel operating member 59 corresponds to area RA1, and the other sides in the operation direction of the travel operating member 59 correspond to areas FA3, LA1, and BA3.
The control device 60 determines that the operation direction of the travel operating member 59 is to the right turn side when the first pilot pressure lf is greater than the second pilot pressure lb and the ratio of the third pilot pressure rf to the first pilot pressure lf is less than a third threshold value β3, and determines that the operation direction of the travel operating member 59 is to the right turn side when the fourth pilot pressure rb is greater than the third pilot pressure rf and the ratio of the second pilot pressure lb to the fourth pilot pressure rb is less than a fourth threshold value β4.

In other words, the control device 60 can determine from the first pilot pressure lf, the second pilot pressure lb, the third pilot pressure rf, and the fourth pilot pressure rb whether the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the region RA1, which is the right turning side, or the operation direction of the travel operating member 59, i.e., whether the operation of the travel operating member 59 is in the region FA3, region LA1, or region BA3 other than the right turning side.

According to this embodiment, as in the first embodiment, by comparing the first pilot pressure and the second pilot pressure acting on the left traveling pump 53L and the third pilot pressure and the fourth pilot pressure acting on the right traveling pump 53L, the operation direction of the traveling operating member 59 can be easily determined without using a sensor such as a potentiometer.
In addition, it is possible to easily determine, based on the pilot pressure alone, whether the operating member 59 has been operated to a side other than the right turning side or whether the operating member 59 has been operated to the right turning side.
In the first to third embodiments described above, the second speed only needs to be faster than the first speed, so the work machine 1 is not limited to having two gears, and can also be applied to a multi-gear (multiple gears) work machine.

In the above-described embodiment, the left traveling motor 36L and the right traveling motor 36R are switched to the first speed and the second speed simultaneously, and automatic deceleration is also performed simultaneously for the left traveling motor 36L and the right traveling motor 36R. However, automatic deceleration may also be performed in a state in which at least one of the left traveling motor 36L and the right traveling motor 36R is switched to the first speed and the second speed, and at least one of the left traveling motor 36L and the right traveling motor 36R is at the second speed.

The travel motors (left travel motor 36L, right travel motor 36R) may be either axial piston motors or radial piston motors. Whether the travel motor is a radial piston motor or a radial piston motor, the motor capacity can be increased to switch to first gear, and the motor capacity can be decreased to switch to second gear.

In addition, when it is determined that the operation direction of the travel operation member 59 is reverse, forward, left turn, or right turn, the imaging device provided on the work machine 1, i.e., an imaging device provided on the work machine 1 that captures an image of the determined direction, may be started. In addition, when it is determined that the operation direction of the travel operation member 59 is a pivot turn, automatic deceleration may be performed, or any processing may be performed after the operation direction of the travel operation member 59 is determined.

In addition, when it is not determined that the operation direction of the travel operation member 59 is a pivot turn or a swivel turn, the automatic deceleration may be restored.
In addition, the control device 60 determines the operation direction of the travel operating member 59 based on the first comparison information including the first pilot pressure and the second pilot pressure, but it may also compare the first pilot pressure and the second pilot pressure and determine whether the operation is a super-spin turn operation or a spin turn operation based on the relative magnitude of each other.

In addition, the control device 60 determines the operation direction of the travel operating member 59 based on the second comparison information including the third pilot pressure and the fourth pilot pressure, but it may also compare the third pilot pressure and the fourth pilot pressure and determine whether it is a super-spin turn operation or a spin turn operation based on the relative magnitude of each other.
Similarly to the above-described embodiment, the control device 60 may determine the operation direction of the travel operating member 59 based on third comparison information including the first pilot pressure and the fourth pilot pressure. Furthermore, the control device 60 may compare the first pilot pressure and the fourth pilot pressure and determine whether the operation is a super-spin turn operation or a spin turn operation based on which is larger.

In addition, the control device 60 may determine the operation direction of the travel operating member 59 based on whether or not either the first pilot pressure lf or the second pilot pressure lb is greater than or equal to a predetermined value, or whether or not both the first pilot pressure lf and the second pilot pressure lb are greater than or equal to a predetermined value.
In addition, the control device 60 may determine the operation direction of the travel operating member 59 based on whether either the third pilot pressure rf or the fourth pilot pressure rb is greater than or equal to a predetermined value, or whether both the third pilot pressure rf and the fourth pilot pressure rb are greater than or equal to a predetermined value.

In addition, the control device 60 may determine the operation direction of the travel operating member 59 based on whether or not either the first pilot pressure lf or the fourth pilot pressure rb is greater than or equal to a predetermined value, or whether or not both the first pilot pressure lf and the fourth pilot pressure rb are greater than or equal to a predetermined value.
In addition, the control device 60 may determine the operation direction of the travel operating member 59 based on whether either the second pilot pressure lb or the third pilot pressure rf is greater than or equal to a predetermined value, or whether both the second pilot pressure lb and the third pilot pressure rf are greater than or equal to a predetermined value.

Finally, in the hydraulic circuit illustrated in FIG. 1 and the hydraulic circuit illustrated in FIG. 5, the control device 60 may combine the configurations disclosed in the above-mentioned first to third embodiments to make judgments about all directions, including the forward direction, the reverse direction, the left turning direction, and the right turning direction.
The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

Reference Signs List 1 Work machine 2 Machine body 5L Left traveling device 5R Right traveling device 36L Left traveling motor 36R Right traveling motor 48a First pressure detection device 48b Second pressure detection device 48c Third pressure detection device 48d Fourth pressure detection device 53L Left traveling pump 53R Right traveling pump 60 Control device

Claims (15)

The aircraft and
A left running device provided on the left side of the aircraft body;
A right running device provided on the right side of the aircraft body;
a left traveling motor capable of transmitting power to the left traveling device;
a right traveling motor capable of transmitting power to the right traveling device;
a left traveling pump having a first pressure receiving portion and a second pressure receiving portion that receive hydraulic oil, and supplying hydraulic oil to the left traveling motor when the hydraulic oil acts on at least one of the first pressure receiving portion and the second pressure receiving portion;
a right traveling pump having a third pressure receiving portion and a fourth pressure receiving portion that receive the hydraulic oil, and supplying the hydraulic oil to the right traveling motor when the hydraulic oil acts on at least one of the third pressure receiving portion and the fourth pressure receiving portion;
a travel operation device that applies hydraulic oil to at least any one of the first pressure receiving portion, the second pressure receiving portion, the third pressure receiving portion, and the fourth pressure receiving portion when the travel operation member is operated;
a first travel oil passage connected to the first pressure receiving portion and passing hydraulic oil acting on the first pressure receiving portion when a travel operating member is operated;
a second travel oil passage connected to the second pressure receiving portion and passing hydraulic oil acting on the second pressure receiving portion when a travel operating member is operated;
a third travel oil passage connected to the third pressure receiving portion and passing hydraulic oil acting on the third pressure receiving portion when a travel operating member is operated;
a fourth travel oil passage connected to the fourth pressure receiving portion and passing hydraulic oil acting on the fourth pressure receiving portion when a travel operating member is operated;
A first pressure detection device capable of detecting a first pilot pressure which is the pressure of the hydraulic oil in the first travel oil passage;
A second pressure detection device capable of detecting a second pilot pressure which is the pressure of the hydraulic oil in the second travel oil passage;
a third pressure detection device capable of detecting a third pilot pressure which is the pressure of the hydraulic oil in the third travel oil passage;
A fourth pressure detection device capable of detecting a fourth pilot pressure which is the pressure of the hydraulic oil in the fourth travel oil passage;
a control device that determines an operation direction of the travel operating member based on either first comparison information including a comparison between the first pilot pressure and the second pilot pressure acting on the left travel pump, or second comparison information including a comparison between the third pilot pressure and the fourth pilot pressure acting on the right travel pump; and
A work machine equipped with the above. The work machine according to claim 1, wherein the control device determines that the operation direction of the travel operating member is other than the reverse side when the first comparison information indicates that the first pilot pressure is greater than the second pilot pressure and the ratio of the second pilot pressure to the first pilot pressure is less than a first threshold value. The work machine according to claim 1 or 2, wherein the control device determines that the operation direction of the travel operation member is other than the reverse side when the second comparison information indicates that the third pilot pressure is greater than the fourth pilot pressure and the ratio of the fourth pilot pressure to the third pilot pressure is less than a second threshold value. The control device is configured to: determine whether the first comparison information indicates that the first pilot pressure is equal to or lower than the second pilot pressure, or a ratio of the second pilot pressure to the first pilot pressure is equal to or higher than a first threshold value; and determine whether the second comparison information indicates that the third pilot pressure is equal to or higher than the fourth pilot pressure.
The work machine according to claim 1 , wherein the operation direction of the travel operating member is determined to be the reverse side when the fourth pilot pressure is equal to or lower than the pilot pressure or when the ratio of the fourth pilot pressure to the third pilot pressure is equal to or higher than a second threshold value. The work machine according to claim 1, wherein the control device determines that the operation direction of the travel operating member is other than the forward direction when the first comparison information indicates that the second pilot pressure is greater than the first pilot pressure and the ratio of the first pilot pressure to the second pilot pressure is less than a first threshold value. The work machine according to claim 1 or 2, wherein the control device determines that the operation direction of the travel operation member is other than the forward direction when the second comparison information indicates that the fourth pilot pressure is greater than the third pilot pressure and the ratio of the third pilot pressure to the fourth pilot pressure is less than a second threshold value. The work machine according to claim 1, wherein the control device determines that the operation direction of the travel operation member is the forward direction when the first comparison information indicates that the second pilot pressure is equal to or lower than the first pilot pressure, or the ratio of the first pilot pressure to the second pilot pressure is equal to or higher than a first threshold value, and the second comparison information indicates that the fourth pilot pressure is equal to or lower than the third pilot pressure, or the ratio of the third pilot pressure to the fourth pilot pressure is equal to or higher than a second threshold value. The work machine according to claim 1, wherein the control device determines that the operation direction of the travel operation member is other than the left turning side when the first comparison information indicates that the first pilot pressure is greater than the second pilot pressure and the ratio of the second pilot pressure to the first pilot pressure is less than a first threshold value. The work machine according to claim 1 or 2, wherein the control device determines that the operation direction of the travel operation member is other than the left turning side when the second comparison information indicates that the fourth pilot pressure is greater than the third pilot pressure and the ratio of the third pilot pressure to the fourth pilot pressure is less than a second threshold value. The control device determines that the operation direction of the travel operating member is the left turning side when the first comparison information indicates that the first pilot pressure is equal to or lower than the second pilot pressure, or the ratio of the second pilot pressure to the first pilot pressure is equal to or higher than a first threshold value, and the second comparison information indicates that the fourth pilot pressure is equal to or lower than the third pilot pressure, or the ratio of the third pilot pressure to the fourth pilot pressure is equal to or higher than a second threshold value. The work machine according to claim 1. The work machine according to claim 1, wherein the control device determines that the operation direction of the travel operation member is other than the right turning side when the first comparison information indicates that the second pilot pressure is greater than the first pilot pressure and the ratio of the first pilot pressure to the second pilot pressure is less than a first threshold value. The work machine according to claim 1 or 2, wherein the control device determines that the operation direction of the travel operation member is other than the right turning side when the second comparison information indicates that the third pilot pressure is greater than the fourth pilot pressure and the ratio of the fourth pilot pressure to the third pilot pressure is less than a second threshold value. The work machine according to claim 1, wherein the control device determines that the operation direction of the travel operating member is the right turning side when the first comparison information indicates that the second pilot pressure is equal to or lower than the first pilot pressure, or a ratio of the first pilot pressure to the second pilot pressure is equal to or higher than a first threshold value, and when the second comparison information indicates that the third pilot pressure is equal to or lower than the fourth pilot pressure, or a ratio of the fourth pilot pressure to the third pilot pressure is equal to or higher than a second threshold value. The aircraft and
A left running device provided on the left side of the aircraft body;
A right running device provided on the right side of the aircraft body;
a left traveling motor capable of transmitting power to the left traveling device;
a right traveling motor capable of transmitting power to the right traveling device;
a left traveling pump having a first pressure receiving portion and a second pressure receiving portion that receive hydraulic oil, and supplying hydraulic oil to the left traveling motor when the hydraulic oil acts on at least one of the first pressure receiving portion and the second pressure receiving portion;
a right traveling pump having a third pressure receiving portion and a fourth pressure receiving portion that receive the hydraulic oil, and supplying the hydraulic oil to the right traveling motor when the hydraulic oil acts on at least one of the third pressure receiving portion and the fourth pressure receiving portion;
a travel operating device that applies hydraulic oil to at least any one of the first pressure receiving portion, the second pressure receiving portion, the third pressure receiving portion, and the fourth pressure receiving portion when the travel operating member is operated;
a first travel oil passage connected to the first pressure receiving portion and passing hydraulic oil acting on the first pressure receiving portion when a travel operating member is operated;
a second travel oil passage connected to the second pressure receiving portion and passing hydraulic oil acting on the second pressure receiving portion when a travel operating member is operated;
a third travel oil passage connected to the third pressure receiving portion and passing hydraulic oil acting on the third pressure receiving portion when a travel operating member is operated;
a fourth travel oil passage connected to the fourth pressure receiving portion and passing hydraulic oil acting on the fourth pressure receiving portion when a travel operating member is operated;
A first pressure detection device capable of detecting a first pilot pressure which is the pressure of the hydraulic oil in the first travel oil passage;
A second pressure detection device capable of detecting a second pilot pressure which is the pressure of the hydraulic oil in the second travel oil passage;
a third pressure detection device capable of detecting a third pilot pressure which is the pressure of the hydraulic oil in the third travel oil passage;
A fourth pressure detection device capable of detecting a fourth pilot pressure which is the pressure of the hydraulic oil in the fourth travel oil passage;
a control device that determines an operation direction of the travel operating member based on either third comparison information including a comparison between the first pilot pressure acting on the left travel pump and the fourth pilot pressure acting on the right travel pump, or fourth comparison information including a comparison between the second pilot pressure acting on the left travel pump and the third pilot pressure acting on the right travel pump; and
A work machine equipped with the above. the first travel oil passage has a first throttle portion downstream of the first pressure detection device, the first throttle portion restricting a flow rate of the hydraulic oil;
The second travel oil passage has a second throttle portion downstream of the second pressure detection device, the second throttle portion restricting a flow rate of the hydraulic oil,
the third travel oil passage has a third throttle portion downstream of the third pressure detection device, the third throttle portion restricting a flow rate of the hydraulic oil;
The work machine according to any one of claims 1 to 14, wherein the fourth travel oil passage has a fourth throttle portion downstream of the fourth pressure detection device, the fourth throttle portion restricting a flow rate of the hydraulic oil.

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