JP2019124359A - Hydraulic system of work machine - Google Patents

Abstract

To provide a hydraulic system of a work machine, which makes it possible to easily perform warming-up, and a work machine provided with the hydraulic system.SOLUTION: A hydraulic system of a work machine comprises: a hydraulic pump P1 discharging hydraulic oil; a tank 22 storing hydraulic oil; operation members 58; operation valves 59 by which a pilot pressure, that is the pressure of hydraulic oil to be outputted, can be set according to operation by the operation members and which have ports connected to the tank; a fifth oil passage 40 connecting the operation valves with the hydraulic pump; a first operation valve 120 that is connected to the fifth oil passage and can change the pressure of hydraulic oil flowing to the operation valves; control valves 56 capable of changing the direction for flowing of hydraulic oil according to the pilot pressure set by the operation valves; a sixth oil passage 43 connecting the operation valves with the control valve; a seventh oil passage 121 connecting the fifth oil passage with the sixth oil passage; and a third setting part 122 that can set the maximum value of the pilot pressure outputted from the operation valves to be less than a changing pressure at which changing of the control valves is performed, by setting the pressure of hydraulic oil of the first operation valve to a predetermined value.SELECTED DRAWING: Figure 9

Description

  The present invention relates to, for example, a hydraulic system of a working machine such as a skid steer loader, a compact truck loader, and a backhoe.

DESCRIPTION OF RELATED ART Conventionally, there exists a thing shown by patent document 1 as a technique which warms up in a working machine.
The work machine of Patent Document 1 includes a pilot pressure control valve that controls the pressure of a pilot oil discharged from a pump and sent to a supply target, and a valve body in which the pilot pressure control valve is incorporated. In Patent Document 1, the valve body is provided with a heat-up oil passage through which the pilot oil discharged from the pump flows, and the pilot oil flowing into the heat-up oil passage is caused to flow to the hydraulic oil tank through the relief valve or the throttle. Heats up the valve body.

JP, 2013-117253, A

In the work machine of Patent Document 1, the valve body has to be processed for warming up, and a hydraulic circuit connecting relief valves or throttles has to be formed in the valve body.
The present invention has been made to solve the problems of the prior art as described above, and provides a hydraulic system of a working machine that can be easily warmed up, and a working machine provided with the hydraulic system. The purpose is to

The technical means of the present invention for solving this technical problem are as follows.
The hydraulic system of the working machine can set a pilot pressure which is the pressure of the hydraulic fluid to be output according to the operation of the hydraulic pump for discharging the hydraulic fluid, the tank for storing the hydraulic fluid, the operation member and the operation member And the operation valve having a port connected to the tank, the fifth oil passage connecting the operation valve and the hydraulic pump, and the fifth oil passage are connected to change the pressure of the hydraulic oil toward the operation valve Control valve capable of switching the flow direction of hydraulic fluid by the pilot pressure set by the operation valve, a sixth oil passage connecting the operation member and the control valve, and By setting the pressure of the hydraulic oil of the seventh oil passage connecting the fifth oil passage and the sixth oil passage and the hydraulic oil of the first operation valve to a predetermined value, the maximum value of the pilot pressure output from the operation valve , Set to less than the switching pressure at which the control valve is switched Includes a third setting unit that ability, the.

  The hydraulic system of the working machine can set a pilot pressure which is the pressure of the hydraulic fluid to be output according to the operation of the hydraulic pump for discharging the hydraulic fluid, the tank for storing the hydraulic fluid, the operation member and the operation member And the operation valve having a port connected to the tank, the fifth oil passage connecting the operation valve and the hydraulic pump, and the fifth oil passage are connected to change the pressure of the hydraulic oil toward the operation valve An eighth oil passage connecting the operation valve and the hydraulic device, and a fifth oil passage, the first hydraulic valve being operable, the hydraulic device operable by the pilot pressure set by the operation valve, the eighth oil passage connecting the operation valve and the hydraulic device The pressure of the hydraulic oil of the ninth oil passage connecting the section between the operation valve and the first operation valve and the eighth oil passage, and the pressure of the first operation valve is set to a predetermined value. The maximum value of the pilot pressure output from the control valve is There has been and a fourth setting unit that can set below working pressure to operate.

  The hydraulic system of the working machine can set a pilot pressure which is the pressure of the hydraulic fluid to be output according to the operation of the hydraulic pump for discharging the hydraulic fluid, the tank for storing the hydraulic fluid, the operation member and the operation member And an operation valve having a port connected to the tank, a fifth oil passage connecting the operation valve and the hydraulic pump, a hydraulic device operable by the pilot pressure set by the operation valve, the operation An eighth oil passage connecting the valve and the hydraulic device, a tenth oil passage connecting the eighth oil passage and the fifth oil passage, and a tenth oil passage connected to the hydraulic device A second operating valve capable of changing the pressure of the hydraulic fluid, and a fifth setting unit capable of setting the pressure of the hydraulic fluid by the second operating valve to less than the operating pressure at which the hydraulic device operates.

The hydraulic system of the working machine includes a measuring device that measures the temperature of the hydraulic fluid, and the third setting unit is configured to determine whether the temperature measured by the measuring device is lower than or equal to a predetermined temperature. By setting the pressure of the hydraulic fluid of the actuating valve to a predetermined value, the maximum value of the pilot pressure output from the actuating valve is kept below the switching pressure at which the control valve is switched.
The hydraulic system of the working machine includes a measuring device for measuring the temperature of the hydraulic fluid, and the fourth setting unit is configured to measure the first temperature when the temperature measured by the measuring device is equal to or lower than a predetermined temperature. By setting the pressure of the hydraulic oil of the actuating valve to a predetermined value, the maximum value of the pilot pressure output from the actuating valve is kept below the actuating pressure at which the hydraulic device operates.

The hydraulic system of the working machine includes a measuring device that measures the temperature of the hydraulic fluid, and the fifth setting unit is configured to determine whether the temperature measured by the measuring device is less than or equal to a predetermined temperature. The pressure of the hydraulic fluid by the actuating valve is maintained below the actuating pressure at which the hydraulic device operates.
The hydraulic system of the working machine includes a switch for setting whether or not to permit switching of the control valve, and the third setting unit does not permit switching of the control valve and the operation of the operating member If the pressure of the hydraulic fluid of the first operating valve is set to a predetermined value, the maximum value of the pilot pressure is kept below the switching pressure, and switching of the control valve is permitted. In this case, the maximum value of the pilot pressure is held above the switching pressure.

In the hydraulic system of a working machine, the fourth setting unit operates the hydraulic device by setting the pressure of the hydraulic oil of the first operation valve to a predetermined value when the operation of the operation member is not performed. When the operation of the operation member is performed, the pressure is maintained at or above the operating pressure at which the hydraulic device operates.
When the operation member is not operated, the fifth setting unit sets the pressure of the hydraulic oil of the second operation valve to a predetermined value and holds the pressure less than the operation pressure at which the hydraulic device operates. When the operation member is operated, the operating pressure is maintained higher than the operating pressure at which the hydraulic device operates.

  According to the present invention, it is possible to easily warm up.

It is the schematic of the travel system hydraulic system in 1st Embodiment. It is the schematic of the working system hydraulic system in 1st Embodiment. It is the figure which showed the relationship between the pilot pressure which acts on the pressure receiving part of the 3rd control valve, and the change of the 3rd control valve. It is a figure which shows the modification of the working system hydraulic system in 1st Embodiment. The part of the travel system hydraulic system in 2nd Embodiment is shown. It is the figure which showed the relationship between the opening degree of a traveling control valve, and the switching of a traveling control valve. It is a figure which shows the modification of the working system hydraulic system in 2nd Embodiment. It is a figure which shows a part of traveling system hydraulic system in 3rd Embodiment. It is a figure which shows the working system hydraulic system in 4th Embodiment. It is a figure which shows a part of working system hydraulic system in 5th Embodiment. It is a figure which shows a part of working system hydraulic system in 6th Embodiment. It is a figure which shows the modification of the working system hydraulic system in 6th Embodiment. It is a figure which shows the working system hydraulic system in 7th Embodiment. It is a figure which shows the working system hydraulic system in 8th Embodiment. It is a side view showing a track loader which is an example of a work machine concerning the present invention. It is a side view showing a part of truck loader in the state where the cabin was raised.

Hereinafter, embodiments of the present invention will be described based on the drawings.
First Embodiment
FIG. 15 shows a side view of a working machine according to the present invention. In FIG. 15, a compact track loader is shown as an example of a work machine. However, the working machine according to the present invention is not limited to the compact track loader, and may be, for example, another type of loader working machine such as a skid steer loader. In addition, a working machine other than the loader working machine may be used.

  As shown in FIGS. 15 and 16, the working machine 1 includes a machine body 2, a cabin 3, a working device 4, and a traveling device 5. In the embodiment of the present invention, the front side (left side in FIG. 15) of the driver sitting on the driver's seat 8 of the work machine 1 is forward, the rear side (right side in FIG. 15) of the driver is rear, and the left side The front side 15 of the driver is described as the left, and the right side of the driver (the rear side in FIG. 15) as the right. Moreover, the horizontal direction which is a direction orthogonal to the front-back direction is demonstrated as a body width direction. The direction from the central part of the airframe 2 to the right or left will be described as the direction outside the airframe. In other words, the extracorporeal direction is the width direction of the vehicle and is the direction away from the vehicle 2. The direction opposite to the direction outside the aircraft will be described as the direction inside the aircraft. In other words, the inside of the vehicle is the width direction of the vehicle and is the direction approaching the vehicle 2.

The cabin 3 is mounted on the airframe 2. The cabin 3 is provided with a driver's seat 8. The work device 4 is mounted on the machine body 2. The traveling device 5 is provided on the outside of the airframe 2. A motor is mounted at the rear of the fuselage 2.
The work device 4 includes 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 vertically swingably provided on the right and left sides of the cabin 3. The work tool 11 is, for example, a bucket, and the bucket 11 is provided at the tip end portion (front end portion) of the boom 10 so as to be vertically pivotable. The lift link 12 and the control link 13 support the base (rear portion) 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 expanding and contracting. The bucket cylinder 15 swings the bucket 11 by expanding and contracting.

The fronts of the left and right booms 10 are connected to each other by an odd-shaped connecting pipe. The base parts (rear parts) of the booms 10 are connected by a circular connection pipe.
The lift link 12, the control link 13 and the boom cylinder 14 are respectively provided on the left and right sides of the machine body 2 corresponding to the booms 10 on the left and right sides.
The lift links 12 are provided longitudinally at the rear of the base of each boom 10. The upper portion (one end side) of the lift link 12 is rotatably supported about a lateral axis via a pivot 16 (first pivot) near the rear of the base of each boom 10. In addition, the lower part (the other end side) of the lift link 12 is rotatably supported around the horizontal axis via a pivot 17 (second pivot) toward the rear of the vehicle body 2. The second pivot shaft 17 is provided below the first pivot shaft 16.

  An upper portion of the boom cylinder 14 is rotatably supported about a lateral axis via a pivot 18 (third pivot). The third pivot shaft 18 is provided at the base of each boom 10 and at the front of the base. The lower portion of the boom cylinder 14 is rotatably supported about a lateral axis via a pivot 19 (a fourth pivot). The fourth pivot shaft 19 is provided near the lower portion of the rear of the airframe 2 and below the third pivot shaft 18.

  The control link 13 is provided in front of the lift link 12. One end of the control link 13 is rotatably supported about a lateral axis via a pivot 20 (a fifth pivot). The fifth pivot shaft 20 is provided at a position corresponding to the front of the lift link 12 in the airframe 2. The other end of the control link 13 is rotatably supported about a lateral axis via a pivot 21 (sixth pivot). The sixth pivot shaft 21 is the boom 10 and is provided in front of the second pivot shaft 17 and above the second pivot shaft 17.

  Each boom 10 swings up and down around the first pivot shaft 16 while the base of each boom 10 is supported by the lift link 12 and the control link 13 by expanding and contracting the boom cylinder 14, and the tip of each boom 10 Rises and falls. The control link 13 swings up and down around the fifth pivot 20 as the booms 10 move up and down. The lift link 12 swings back and forth around the second pivot shaft 17 as the control link 13 swings up and down.

Instead of the bucket 11, another work tool can be attached to the front of the boom 10. Other working tools are, for example, attachments such as hydraulic crushers, hydraulic breakers, angle blooms, earth augers, pallet forks, sweepers, mowers, snow blowers, and the like (preliminary attachments).
A connecting member 50 is provided at the front of the left boom 10. The connection member 50 is a device that connects the hydraulic device equipped to the spare attachment and the first pipe member such as a pipe provided to the boom 10. Specifically, the first pipe can be connected to one end of the connection member 50, and the second pipe connected to the hydraulic device of the backup attachment can be connected to the other end. Thus, the hydraulic oil flowing through the first pipe passes through the second pipe and is supplied to the hydraulic device.

The bucket cylinders 15 are respectively disposed near the front of each boom 10. By expanding and contracting the bucket cylinder 15, the bucket 11 is swung.
In the present embodiment, crawler type (including semi crawler type) traveling devices are adopted for the left and right traveling devices 5. In addition, you may employ | adopt the travel apparatus of the wheel type which has a front wheel and a rear wheel.

Next, the hydraulic system of the working machine according to the present invention will be described.
As shown in FIGS. 1 and 2, the hydraulic system can be roughly divided into a traveling system hydraulic system 30A and a working system hydraulic system 30B.
The travel system hydraulic system 30A will be described.
As shown in FIG. 1, the traveling hydraulic system 30A mainly drives a left traveling motor device (first traveling motor device) 31L and a right traveling motor device (second traveling motor device) 31R. . The traveling system hydraulic system 30A also includes a prime mover 32, a direction switching valve 33, a first hydraulic pump P1, a first traveling motor device 31L, a second traveling motor device 31R, and a hydraulic device 34. .

  The prime mover 32 is composed of an electric motor, an engine and the like. In this embodiment, the prime mover 32 is an engine. The first hydraulic pump P1 is a pump driven by the power of the prime mover 32, and is constituted by a fixed displacement gear pump. The first hydraulic pump P1 can discharge the hydraulic oil stored in the tank 22. In particular, the first hydraulic pump P1 discharges hydraulic oil mainly used for control. For convenience of explanation, the tank 22 storing hydraulic oil may be referred to as a hydraulic oil tank. Further, among the hydraulic oil discharged from the first hydraulic pump P1, the hydraulic oil used for control may be referred to as a pilot oil, and the pressure of the pilot oil may be referred to as a pilot pressure.

  A discharge oil passage (fifth oil passage) 40 for flowing hydraulic oil (pilot oil) is provided on the discharge side of the first hydraulic pump P1. The discharge oil passage 40 is provided with a filter 35, a direction switching valve 33, a first travel motor device 31L and a second travel motor device 31R. Between the filter 35 and the direction switching valve 33, a charge oil passage 41 branched from the discharge oil passage 40 is provided. The charge oil passage 41 leads to the hydraulic device 34.

The direction switching valve 33 is an electromagnetic valve that changes the rotation of the first travel motor device 31L and the second travel motor device 31R, and is a two position switching valve that can be switched between the first position 33a and the second position 33b by excitation. It is. The switching operation of the direction switching valve 33 is performed by an operation member or the like (not shown).
The first travel motor device 31L is a motor for transmitting power to the drive shaft of the travel device 5 provided on the left side of the machine body 2. The second travel motor device 31R is a motor for transmitting power to the drive shaft of the travel device provided on the right side of the vehicle body 2.

The first traveling motor device 31L includes an HST motor (traveling motor) 36, a swash plate switching cylinder 37, and a traveling control valve (hydraulic switching valve) 38A. The HST motor 36 is a swash plate type variable displacement axial motor and can change the vehicle speed (rotation) to the first speed or the second speed.
The swash plate switching cylinder 37 is a cylinder that changes the angle of the swash plate of the HST motor 36 by expansion and contraction. The travel control valve 38A is a valve that extends and retracts the swash plate switching cylinder 37 to one side or the other side, and is a two-position switching valve that switches between the first position 38a and the second position 38b. The switching operation of the travel control valve 38A is performed by the direction switching valve 33 located on the upstream side connected to the travel control valve 38A.

  As described above, according to the first travel motor device 31L, when the direction switching valve 33 is set to the first position 33a by the operation of the operation member, the pilot oil escapes in the section between the direction switching valve 33 and the travel control valve 38A, The travel control valve 38A is switched to the first position 38a. As a result, the swash plate switching cylinder 37 is contracted, and the HST motor 36 is in the first speed state. Further, when the direction switching valve 33 is brought to the second position 33b by the operation of the operation member, pilot oil is supplied to the travel control valve 38A through the direction switching valve 33, and the travel control valve 38A is switched to the second position 38b. As a result, the swash plate switching cylinder 37 is extended, and the HST motor 36 is in the second speed state.

The second travel motor device 31R operates in the same manner as the first travel motor device 31L. The configuration and operation of the second travel motor device 31R are the same as those of the first travel motor device 31L, and therefore the description thereof is omitted.
The hydraulic device 34 is a device for driving the first travel motor device 31L and the second travel motor device 31R, and includes a drive circuit (drive circuit for the left) 34L for driving the first travel motor device 31L and a second travel motor And a drive circuit (right drive circuit) 34R for driving the device 31R.

  The drive circuits 34L and 34R respectively include an HST pump (traveling hydraulic pump) 53, oil shifting passages 57h and 57i, and a second charge oil passage 57j. The shift oil passages 57 h and 57 i are oil passages connecting the HST pump 53 and the HST motor 36. The second charge oil passage 57j is connected to the transmission oil passages 57h and 57i, and replenishes the hydraulic oil from the first hydraulic pump P1 to the transmission oil passages 57h and 57i.

  The HST pump 53 is a swash plate type variable displacement axial pump driven by the power of the prime mover 32. The HST pump 53 has a forward pressure receiving portion 53a on which a pilot pressure acts and a reverse pressure receiving portion 53b, and the angle of the swash plate is changed by the pilot pressure acting on the pressure receiving portions 53a and 53b. By changing the angle of the oblique plate, it is possible to change the output of the HST pump 53 (discharge amount of hydraulic oil) and the discharge direction of hydraulic oil.

  The output of the HST pump 53 and the discharge direction of the hydraulic oil can be changed by the travel lever 54 provided around the driver's seat 8. The travel lever 54 is supported so as to be capable of tilting in a diagonal direction between front and rear, right and left and front and rear, left and right from a neutral position. A discharge oil passage (fifth oil passage) 40 is connected to the travel lever 54, and hydraulic oil (pilot oil) from the first hydraulic pump P1 can be supplied. By tilting the traveling lever 54, the pilot valve (operation valve) 55 provided at the lower part of the traveling lever 54 can be operated.

  When the travel lever 54 is tilted forward, the forward pilot valve 55A is operated to output a pilot pressure from the forward pilot valve 55A. The pilot pressure acts on the forward pressure receiving portion 53a of the left drive circuit 34L and the forward pressure receiving portion 53a of the right drive circuit 34R. As a result, the output shaft of the HST motor 36 performs forward rotation (forward rotation) at a speed proportional to the amount of tilt of the travel lever 54, and the work machine 1 goes straight ahead.

  Further, when the travel lever 54 is tilted rearward, the reverse pilot valve 55B is operated to output a pilot pressure from the reverse pilot valve 55B. The pilot pressure acts on the reverse pressure receiving portion 53b of the left drive circuit 34L and the reverse pressure receiving portion 53b of the right drive circuit 34R. As a result, the output shaft of the HST motor 36 reverses rotation (reverse rotation) at a speed proportional to the amount of tilt of the travel lever 54, and the work machine 1 goes straight forward.

  Further, when the travel lever 54 is tilted to the right, the right turn pilot valve 55C is operated to output a pilot pressure from the right turn pilot valve 55C. The pilot pressure also acts on the forward pressure receiving portion 53a of the left drive circuit 34L and the reverse pressure receiving portion 53b of the right drive circuit 34R. As a result, the output shaft of the left HST motor 36 rotates forward, and the output shaft of the right HST motor 36 reverses, and the work implement 1 turns to the right.

  When the travel lever 54 is tilted forward, the forward pilot valve 55A is operated to output a pilot pressure from the forward pilot valve 55A. The pilot pressure acts on the forward pressure receiving portion 53a of the left drive circuit 34L and the forward pressure receiving portion 53a of the right drive circuit 34R. As a result, the output shaft of the HST motor 36 performs forward rotation (forward rotation) at a speed proportional to the amount of tilt of the travel lever 54, and the work machine 1 goes straight ahead.

  Further, when the travel lever 54 is tilted rearward, the reverse pilot valve 55B is operated to output a pilot pressure from the reverse pilot valve 55B. The pilot pressure acts on the reverse pressure receiving portion 53b of the left drive circuit 34L and the reverse pressure receiving portion 53b of the right drive circuit 34R. As a result, the output shaft of the HST motor 36 reverses rotation (reverse rotation) at a speed proportional to the amount of tilt of the travel lever 54, and the work machine 1 goes straight forward.

  Further, when the travel lever 54 is tilted to the right, the right turn pilot valve 55C is operated to output a pilot pressure from the right turn pilot valve 55C. The pilot pressure also acts on the forward pressure receiving portion 53a of the left drive circuit 34L and the reverse pressure receiving portion 53b of the right drive circuit 34R. As a result, the output shaft of the left HST motor 36 rotates forward, and the output shaft of the right HST motor 36 reverses, and the work implement 1 turns to the right.

  Further, when the travel lever 54 is tilted to the left, the left turn pilot valve 55D is operated to output a pilot pressure from the left turn pilot valve 55D. The pilot pressure also acts on the forward pressure receiving portion 53a of the right drive circuit 34R and the reverse pressure receiving portion 53b of the left drive circuit 34L. As a result, the output shaft of the right HST motor 36 rotates forward, and the output shaft of the left HST motor 36 reverses rotation, and the work implement 1 turns to the left.

Also, when the traveling lever 54 is tilted in an oblique direction, the differential direction of the pilot pressure acting on the forward pressure receiving portion 53a and the reverse pressure receiving portion 53b of each drive circuit causes the rotation direction and rotation of the output shaft of the HST motor 36. The speed is determined, and the work machine turns right or left while advancing or reversing.
The working hydraulic system 30B will be described.

As shown in FIG. 2, the working hydraulic system 30B is a system for operating the boom 10, the bucket 11, the spare attachment, etc., and includes a plurality of control valves 56 and a working hydraulic pump (second hydraulic pump) P2. Have.
The second hydraulic pump P2 is a pump installed at a position different from that of the first hydraulic pump P1, and is configured by a fixed displacement gear pump. The second hydraulic pump P2 can discharge the hydraulic oil stored in the hydraulic oil tank 22. In particular, the second hydraulic pump P2 mainly discharges hydraulic oil that operates the hydraulic actuator.

  A main oil passage (oil passage) 39 is provided on the discharge side of the second hydraulic pump P2. A plurality of control valves 56 are connected to the main oil passage 39. The control valve 56 is a valve capable of switching the flow direction of the hydraulic oil by the pilot pressure of the pilot oil. Further, the control valve 56 is a valve capable of controlling hydraulic equipment. The hydraulic device is, for example, a device for controlling (driving) a hydraulic device such as a boom, bucket, hydraulic crusher, hydraulic breaker, angle bloom, earth auger, pallet fork, sweeper, mower, snow blower, etc. , Hydraulic cylinders, hydraulic motors, etc.

  As shown in FIG. 2, the plurality of control valves 56 are a first control valve 56A, a second control valve 56B, and a third control valve 56C. The first control valve 56A is a valve that controls a hydraulic cylinder (boom cylinder) 14 that controls a boom. The second control valve 56B is a valve that controls a hydraulic cylinder (bucket cylinder) 15 that controls a bucket. The third control valve 56C is a valve for controlling a hydraulic device (hydraulic cylinder, hydraulic motor) mounted on a preliminary attachment such as a hydraulic crusher, hydraulic breaker, angle bloom, earth auger, pallet fork, sweeper, mower, snow blower or the like. is there.

Each of the first control valve 56A and the second control valve 56B is a pilot-operated direct-acting spool type three-position switching valve. The first control valve 56A and the second control valve 56B are switched by the pilot pressure to the neutral position, a first position different from the neutral position, and a second position different from the neutral position and the first position.
The boom cylinder 14 is connected to the first control valve 56A via an oil passage, and the bucket cylinder 15 is connected to the second control valve 56B via an oil passage.

  The operation of the boom 10 and the bucket 11 can be performed by an operation lever 58 provided around the driver's seat 8. The operating lever 58 is supported so as to be capable of tilting in the front-rear, left-right, and diagonal directions from the neutral position. By tilting the operating lever 58, it is possible to operate a plurality of pilot valves (operating valves) 59A, 59B, 59C, 59D provided at the lower part of the operating lever 58. The pilot valves 59A, 59B, 59C, 59D and the first hydraulic pump P1 are connected by a discharge oil passage (fifth oil passage) 40. Further, the pilot valves 59A, 59B, 59C, 59D have a discharge port (port) connected to the hydraulic oil tank 22, and are connected to the hydraulic oil tank 22 via the discharge oil passage 42.

  The plurality of pilot valves (operation valves) 59A, 59B, 59C, 59D and the plurality of control valves 56 are mutually connected by a plurality of oil passages (sixth oil passages) 43a, 43b, 43c, 43d. Specifically, the pilot valve 59A is connected to the first control valve 56A via the sixth oil passage 43a. The pilot valve 59B is connected to the first control valve 56A via a sixth oil passage 43b. The pilot valve 59C is connected to the first control valve 56B via a sixth oil passage 43c. The pilot valve 59D is connected to the first control valve 56B via a sixth oil passage 43d. The pilot valves (operation valves) 59A, 59B, 59C, 59D can set the pressure of the hydraulic fluid to be output according to the operation of the operation lever 58, respectively.

Specifically, when the control lever 58 is tilted forward, the lowering pilot valve (operating valve) 59A is operated to set the pilot pressure of the pilot oil output from the lowering pilot valve 59A. The pilot pressure acts on the pressure receiving portion of the first control valve 56A, the boom cylinder 14 contracts, and the boom 10 descends.
When the control lever 58 is tilted rearward, the lift pilot valve (control valve) 59B is operated to set the pilot pressure of the pilot oil output from the lift pilot valve 59B. The pilot pressure acts on the pressure receiving portion of the first control valve 56A, the boom cylinder 14 is extended, and the boom 10 is raised.

When the control lever 58 is tilted to the right, the bucket dump pilot valve (control valve) 59C is operated to set the pilot pressure of the pilot oil output from the pilot valve 59C. The pilot pressure acts on the pressure receiving portion of the second control valve 56B, and the bucket cylinder 15 extends, and the bucket 11 performs a dumping operation.
When the control lever 58 is tilted to the left, the pilot valve (control valve) 59D for the bucket squee is operated to set the pilot pressure of the pilot oil output from the pilot valve 59D. The pilot pressure acts on the pressure receiving portion of the second control valve 56B, the bucket cylinder 15 contracts, and the bucket 11 squeezes.

  The third control valve 56C is a pilot-type direct-acting spool type three-position switching valve. The third control valve 56C is switched to the first position 62a, the second position 62b, and the third position (neutral position) 62c by the pilot pressure. That is, the third control valve 56C switches the first position 62a, the second position 62b, and the third position 62c to control the direction, flow rate and pressure of the hydraulic fluid directed to the hydraulic equipment of the backup attachment.

An oil supply and discharge passage 83 is connected to the third control valve 56C. One end of the oil supply and discharge passage 83 is connected to the oil supply and discharge port of the third control valve 56C, the middle part of the oil supply and discharge passage 83 is connected to the connecting member 50, and the other end of the oil supply and discharge passage 83 is Connected to the hydraulic equipment of the backup attachment. The oil supply and discharge passage 83 is configured by the first pipe and the second pipe as described above.
Specifically, the oil supply and discharge passage 83 includes a first oil supply and discharge passage 83a connecting the first supply and discharge port of the third control valve 56C and the first port of the connection member 50. In addition, the oil supply and discharge passage 83 includes a second oil supply and discharge passage 83b that connects the second supply and discharge port of the third control valve 56C and the second port of the connection member 50. That is, by operating the third control valve 56C, hydraulic fluid flows from the third control valve 56C toward the first supply / discharge oil passage 83a, or from the third control valve 56C toward the second supply / discharge oil passage 83b. Hydraulic fluid can flow.

  The third control valve 56C is operated by the plurality of proportional valves 60. The proportional valve 60 is a solenoid valve whose opening degree can be changed by excitation. The plurality of proportional valves 60 are a first proportional valve 60A and a second proportional valve 60B. A discharge oil passage 40 is connected to the first proportional valve 60A and the second proportional valve 60B. A pilot oil, which is a hydraulic oil used for control among the hydraulic oil, is supplied to the first proportional valve 60A and the second proportional valve 60B from the first hydraulic pump P1.

The third control valve 56C and the proportional valve 60 (the first proportional valve 60A and the second proportional valve 60B) are connected by a first oil passage 86.
The first oil passage 86 is an oil passage that allows pilot oil to flow to the third control valve 56C via the proportional valve 60 (the first proportional valve 60A and the second proportional valve 60B). The first oil passage 86 is formed of a steel pipe, a pipe, a hose or the like. The first oil passage 86 includes a first control oil passage 86a connecting the first proportional valve 60A and the pressure receiving portion 61a of the third control valve 56C, and a pressure receiving portion 61b of the second proportional valve 60B and the third control valve 56C. And a second control oil passage 86b connecting the two.

  Therefore, when the first proportional valve 60A is opened, the pilot oil acts on the pressure receiving portion 61a of the third control valve 56C via the first control oil passage 86a, and the pressure of the pressure receiving portion 61a is determined by the opening degree of the first proportional valve 60A. The applied pilot pressure is determined. When the pilot pressure applied to the pressure receiving portion 61a becomes equal to or greater than a predetermined value, the third control valve 56C switches from the third position (neutral position) 62c to the first position 62a by the movement of the spool. Further, when the second proportional valve 60B is opened, the pilot oil acts on the pressure receiving portion 61b of the third control valve 56C via the second control oil passage 86b, and the pressure receiving portion 61b is operated by the opening degree of the second proportional valve 60B. The applied pilot pressure is determined. When the pilot pressure applied to the pressure receiving portion 61b becomes equal to or higher than a predetermined value, the third control valve 56C switches from the third position (neutral position) 62c to the second position 62b due to the movement of the spool.

  A second oil passage 87 is connected to the first oil passage 86. The second oil passage 87 is an oil passage connecting the first oil passage 86 and the hydraulic oil tank (tank) 22. That is, the second oil passage 87 is an oil passage connecting the hydraulic oil tank 22 between the third control valve 56C and the proportional valve 60. Specifically, the second oil passage 87 includes a first discharge oil passage 87 a connecting the first control oil passage 86 a and the hydraulic oil tank 22, and a second oil passage 87 b connecting the second control oil passage 86 b and the hydraulic oil tank 22. And a drain oil passage 87b. Further, the second oil passage 87 is provided with a throttling portion 88 for reducing the flow rate of the hydraulic oil flowing to the second oil passage 87. The throttling portion 88 includes a first throttling portion 88 a provided in the first control oil passage 86 a and a second throttling portion 88 b provided in the second control oil passage 86 b.

  The control device 90 performs excitation of the proportional valve 60 (the first proportional valve 60A and the second proportional valve 60B). The control device 90 is configured of a CPU and the like. The control device 90 includes a first setting unit 91 and a storage unit 92. The first setting unit 91 is configured of a program incorporated in the control device 90, an electric / electronic circuit, and the like. The first setting unit 91 sets the opening degree of the proportional valve 60 by performing predetermined excitation on the proportional valve 60.

Further, an operating member 93 is connected to the control device 90. An operation amount (for example, a slide amount, a swing amount, and the like) of the operation member 93 is input to the control device 90. The operation member 93 is configured by, for example, a swingable seesaw type switch, a slidable slide type switch, or a pushable push type switch.
Hereinafter, the third control valve 56C, the proportional valve 60, the control device 90, the first setting unit 91, the storage unit 92, the operation member 93, and the like will be described in detail.

FIG. 3 is a view showing the relationship between the pilot pressure acting on the pressure receiving portions 61a and 61b of the third control valve 56C and the switching of the third control valve 56C.
As shown in FIG. 3, for example, if the pilot pressure acting on the pressure receiving portion 61a of the third control valve 56C is less than the pressure (switching pressure) A1 at the boundary to switch from the neutral position 62c to the first position 62a, the third The control valve 56C remains at the neutral position 62c.

  Here, the first setting unit 91 of the control device 90 has a pilot pressure to be applied to the third control valve 56C lower than the switching pressure A1 when the operation member 93 is not operated (the operation amount is zero). It can be set to Specifically, in a state where the operation member 93 is not operated, the first setting unit 91 performs control of applying a predetermined pilot pressure (referred to as a first pressurization B1) to the pressure receiving unit 61a of the third control valve 56C. The first preload B1 is greater than or equal to zero and less than the switching pressure A1 (0 <B1 <A1). That is, the first setting unit 91 sets the opening degree of the first proportional valve 60A such that the pilot pressure acting on the pressure receiving unit 61a becomes the first pressurization B1. In other words, the first setting unit 91 sets the pilot pressure of the first control oil passage 86a to zero or more and less than the switching pressure A1.

For example, the storage unit 92 of the control device 90 stores an opening degree (first switching opening degree) of the first proportional valve 60A at the switching pressure A1 or a current value corresponding to the first switching opening degree. There is. The first setting unit 91 applies a predetermined current to the solenoid 60a of the first proportional valve 60A to hold the opening degree of the first proportional valve 60A at zero or more and less than the first switching opening degree.
Similarly, if the pilot pressure acting on the pressure receiving portion 61b of the third control valve 56C is lower than the pressure (switching pressure) A2 at the boundary to switch from the neutral position 62c to the second position 62b, the third control valve 56C Remains at the third position 62c. The first setting unit 91 performs control to apply a predetermined pilot pressure (referred to as a second pressurization B2) to the pressure receiving unit 61b of the third control valve 56C in a state where the operation member 93 is not operated. The second preload B2 is greater than or equal to zero and less than the switching pressure A2 (0 <B2 <P2). That is, the first setting unit 91 sets the opening degree of the second proportional valve 60B such that the pilot pressure acting on the pressure receiving unit 61b becomes the second preload B2. In other words, the first setting unit 91 sets the pilot pressure of the second control oil passage 86b to zero or more and less than the switching pressure A2.

For example, the storage unit 92 of the control device 90 stores the current value corresponding to the opening degree (second switching opening degree) of the second proportional valve 60B at the switching pressure A2 or the second switching opening degree. There is. The first setting unit 91 applies a predetermined current to the solenoid of the second proportional valve 60B to hold the opening degree of the second proportional valve 60B at zero or more and less than the second switching opening degree.
In this embodiment, the switching pressure A1 and the switching pressure A2 may have the same value but different values. Further, the switching pressure A1 and the switching pressure A2 can be set by a spring provided in the third control valve 56C (a spring for returning the spool moving with the pilot pressure to the neutral position).

  As described above, according to the first setting unit 91, the pilot pressure that acts on the pressure receiving portion of the third control valve 56C is held at less than the switching pressure A1, A2. Therefore, pilot oil flows from the proportional valve 60 (first proportional valve 60A, second proportional valve 60B) to the first oil passage 86 (first control oil passage 86a, second control oil passage 86b), and the pilot oil It flows from the first oil passage 86 to the second oil passage 87 (the first discharge oil passage 87 a, the second discharge oil passage 87 b) and returns to the hydraulic oil tank 22. That is, in the state where the hydraulic device is not operated (the state where the third control valve 56C is held at the neutral position), the hydraulic oil of the hydraulic oil tank 22 is transferred to the first pump P1, the discharge oil passage 40, the proportional valve 60, The oil can be circulated through the first oil passage 86 and the second oil passage 87, and the temperature of the hydraulic oil can be raised by the circulation. In other words, the hydraulic system can be warmed up.

  The control to apply the first pressurization B1 and the second pressurization B2 by the first setting unit 91 (adjustment control of the proportional valve 60) may be alternately performed by the first proportional valve 60A and the second proportional valve 60B. Good. For example, the first setting unit 91 holds the opening degree of the first proportional valve 60A for at least zero and less than the first switching opening degree for a predetermined time, and then stops the opening degree control for the first proportional valve 60A. Opening control is started to hold the opening of the second proportional valve 60B for at least zero and less than the second switching opening for a predetermined time.

On the other hand, when the operation member 93 is operated (the operation amount is not zero), the current corresponding to the operation amount of the operation member 93 is indicated by the solenoid 60a of the first proportional valve 60A or the solenoid 60b of the second proportional valve 60B. Apply to That is, the opening degree of the first proportional valve 60A or the second proportional valve 60B is changed in accordance with the amount of operation of the operation member 93.
For example, when the pilot pressure of the pressure receiving portion 61a becomes equal to or higher than the switching pressure as a result of adjusting the opening degree of the first proportional valve 60A by swinging or sliding the operating member 93 in one direction, the third control valve 56C The third control valve 56C is switched to the first position 62a. Also, for example, when the pilot pressure of the pressure receiving portion 61b becomes equal to or higher than the switching pressure as a result of adjusting the opening degree of the second proportional valve 60A by swinging or sliding the operation member 93 in the other direction, the third control The spool of the valve 56C moves to switch the third control valve 56C to the second position 62b.

  FIG. 4 is a view showing a modified example of the working hydraulic system in the first embodiment. As shown in FIG. 4, the working hydraulic system 30B includes a measuring device 95 that measures the temperature of the hydraulic fluid. The measuring device 95 is provided, for example, in the hydraulic oil tank 22, either on the main oil passage 39, the discharge oil passage 40, or on the inlet side of the proportional valve 60. The temperature measured by the measuring device 95 is input to the controller 90.

  The first setting unit 90 sets the pilot pressure applied to the third control valve 56C to the pilot of the third control valve 56C when the temperature of the measuring device 95 acquired by the control device 90 is equal to or lower than a predetermined temperature. Keep the pressure lower than the pressure. For example, when the operating member 93 is not operated and the temperature measured by the measuring device 95 is 0 ° C. or less, the opening degree of the first proportional valve 60A is maintained at zero or more and less than the first switching opening degree The opening degree of the second proportional valve 60B is maintained at zero or more and less than the second switching opening degree. Then, when the temperature measured by the measuring device 95 exceeds 10 ° C., the opening control of the proportional valve 60 is stopped. Preferably, the first setting unit 90 sets the degree of opening of the proportional valve 60 (pilot pressure to be applied to the third control valve 56C) according to the temperature measured by the measuring device 95. Specifically, the first setting unit 90 increases the opening degree of the first proportional valve 60A (increases the pressure to be applied) as the temperature measured by the measuring device 95 decreases, and the temperature measured by the measuring device 95 increases. The opening degree of the first proportional valve 60A is made smaller (the pressure to be applied is made smaller). For example, when the temperature is -20 ° C, the first setting unit 90 sets the pilot pressure applied to the third control valve 56C at 0.3 MPa, and when the temperature is -10 ° C, the pilot pressure applied to the third control valve 56C is zero. Set to 2 MPa.

Second Embodiment
FIG. 5 shows a part of a traveling system hydraulic system in the second embodiment. FIG. 5 shows a circuit in which the travel control valve 38A shown in the first embodiment is changed to another travel switching valve 38B in the travel system hydraulic system 30A. In the second embodiment, a configuration different from the first embodiment will be described.
As shown in FIG. 5, the travel control valve 38B is configured of an electromagnetic three-position switching valve that switches to a first position 38a, a second position 38b, and a third position (neutral position) 38c. That is, by switching the travel control valve 38A to the first position 38a, the second position 38b, and the third position (neutral position) 38c, the swash plate switching cylinder 37, which is a hydraulic device, is expanded or contracted to one side or the other side. .

The travel control valve 38B is connected to the discharge oil passage 40 and to the third oil passage (supply / discharge oil passage) 100. The third oil passage 100 is an oil passage connecting the travel control valve 38B and the swash plate switching cylinder 37.
The third oil passage 100 includes a first oil supply / discharge passage 100a connecting the first supply / discharge port of the travel control valve 38B and the first port (bottom port) of the swash plate switching cylinder 37. Further, the third oil passage 100 includes a second oil supply / discharge passage 100 b connecting the second supply / discharge port of the travel control valve 38 B and the second port (rod port) of the swash plate switching cylinder 37. That is, by operating the travel control valve 38B, hydraulic fluid flows from the travel control valve 38B toward the first oil supply / discharge passage 100a, or hydraulic fluid from the travel control valve 38B toward the second oil supply / discharge passage 100b. Can flow.

The fourth oil passage 101 is connected to the third oil passage 100. The fourth oil passage 101 is an oil passage connecting the third oil passage 100 and the hydraulic oil tank (tank) 22. That is, the fourth oil passage 101 is an oil passage connecting the travel control valve 38B and the swash plate switching cylinder 37 and the hydraulic oil tank 22.
Specifically, the fourth oil passage 101 connects the first discharge oil passage 101 a connecting the first oil supply / discharge oil passage 100 a and the hydraulic oil tank 22, and connects the second oil supply / discharge oil passage 100 b and the hydraulic oil tank 22. And a second discharge oil passage 101b. Further, the fourth oil passage 101 is provided with a throttling portion 102 that reduces the flow rate of the hydraulic oil flowing to the fourth oil passage 101. The throttling portion 102 includes a first throttling portion 102 a provided in the first oil supply and discharge passage 100 a and a second throttling portion 102 b provided in the second oil supply and discharge passage 100 b.

  The control device 105 performs excitation of the travel control valve 38B and the like. The control device 105 is configured of a CPU and the like. The control device 105 includes a second setting unit 106 and a storage unit 107. The second setting unit 106 includes a program, an electric / electronic circuit and the like incorporated in the control device 105. The second setting unit 106 sets the opening degree of the travel control valve 38B by performing predetermined excitation on the travel control valve 38B.

Further, an operation member 108 is connected to the control device 105. An operation amount (for example, a slide amount, a swing amount, and the like) of the operation member 108 is input to the control device 105. The operation member 108 is configured by, for example, a swingable seesaw type switch, a slideable slide type switch, or a pushable push type switch.
Hereinafter, the travel control valve 38B, the travel control valve 38B, the control device 105, the second setting unit 106, the storage unit 107, the operation member 108, and the like will be described in detail.
The second setting unit 106 of the control device 105 can set the opening degree of the travel control valve 38B to less than the switching opening degree of the travel control valve 38B when the operation member 108 is not operated (the operation amount is zero) It is.

FIG. 6 is a diagram showing the relationship between the opening degree of the travel control valve 38B and the switching of the travel control valve 38B.
As shown in FIG. 6, for example, if the opening degree of the travel control valve 38B is less than the opening degree (first switching opening degree) M1 of the boundary to switch from the neutral position 38c to the first position 38a, the travel control valve 38B is It remains at the neutral position 38c. Here, the smallest opening degree in the case where the hydraulic oil passes from the discharge oil passage 40 to the travel control valve 38B and flows to the first oil supply and discharge passage 100a is defined as the minimum opening degree M3. The second setting unit 106 sets the opening degree K1 of the travel control valve 38B to the minimum opening degree M3 or more and less than the first switching opening degree M1 (M3 ≦ K1 <M1) when the operation member 108 is not operated.

For example, the storage unit 107 of the control device 105 stores a first switching opening degree M1 (a current value corresponding to the first switching opening degree M1) and a minimum opening degree M3. When the operation amount of the operation member 108 is zero, the second setting unit 106 applies a predetermined current to the solenoid of the travel control valve 38B to open the travel control valve 38A at the opening K1 of the minimum opening M3 or more. It is held below the first switching opening degree M1.
If the opening degree of the travel control valve 38B is less than the opening degree (second switching opening degree) M2 of the boundary to switch from the neutral position 38c to the second position 38b, the travel control valve 38B remains at the neutral position 38c. . The second setting unit 106 sets the opening degree K2 of the travel control valve 38B to the minimum opening degree M3 or more and less than the second switching opening degree M2 (M3 ≦ K1 <M2) when the operation member 108 is not operated.

For example, the storage unit 107 of the control device 105 stores a second switching opening degree M2 (a current value corresponding to the second switching opening degree M2) and a minimum opening degree M3. When the operation amount of the operation member 108 is zero, the second setting unit 106 applies a predetermined current to the solenoid of the travel control valve 38B to open the travel control valve 38A at the opening K2 of the minimum opening M3 or more. It is held at less than the second switching opening degree M2.
In this embodiment, the first switching opening degree M1 and the second switching opening degree M2 may have the same value but different values. Further, the first switching opening degree M1 and the second switching opening degree M2 can be set by a spring provided in the travel control valve 38B (a spring for returning the spool moving with the pilot pressure to the neutral position) is there.

  As described above, according to the second setting unit 106, the travel control valve 38B is held at less than the first switching opening degree M1 and the second switching opening degree M2. Therefore, pilot oil flows from the travel control valve 38B to the third oil passage 100 (the first oil supply / discharge oil passage 100a, the second oil supply / discharge oil passage 100b), and the pilot oil flows from the third oil passage 100 to the fourth oil passage It flows to 101 (first discharge oil passage 101 a, second discharge oil passage 101 b) and returns to the hydraulic oil tank 22. That is, in the state where the hydraulic device is not operated (the state where the third control valve 56C is held at the neutral position), the hydraulic oil of the hydraulic oil tank 22 is divided into the first pump P1, the discharge oil passage 40, the travel control valve 38B It can be circulated through the third oil passage 100 and the fourth oil passage 101, and the temperature of the hydraulic oil can be raised by the circulation. In other words, the hydraulic system can be warmed up.

  Note that control to set the openings K1 and K2 to the minimum opening M3 or more and less than the first switching opening M1 or the minimum opening M3 or more and less than the second switching opening M2 by the second setting unit 106 (travel control valve The adjustment control of 38 B) may be alternately performed. For example, the second setting unit 106 holds the opening degree of the travel control valve 38B at less than the first switching opening degree for a predetermined time, and then stops the opening degree control for the travel control valve 38B, and then the travel control valve 38B. Opening control for holding the opening degree of the second switching opening degree for a predetermined time less than the second switching opening degree is started.

On the other hand, when the operation member 108 is operated (the operation amount is not zero), a current corresponding to the operation amount of the operation member 108 is applied to the solenoid of the travel control valve 38B or the solenoid of the travel control valve 38B. That is, the travel control valve 38B changes the opening degree in accordance with the amount of operation of the operation member 108.
For example, when the opening degree of the travel control valve 38B becomes equal to or greater than the switching opening degree by swinging or sliding the operation member 108 in one direction, the spool of the travel control valve 38B moves and the travel control valve 38B , Switch to the first position 38a. Also, for example, when the opening degree of the travel control valve 38B becomes equal to or more than the switching opening degree by swinging or sliding the operation member 108 in the other direction, the spool of the travel control valve 38B moves and the travel control valve In 38B, the travel control valve 38B switches to the second position 38b.

  FIG. 7 is a view showing a modified example of the working hydraulic system in the second embodiment. As shown in FIG. 7, the traveling system hydraulic system 30A includes a measuring device 109 that measures the temperature of the hydraulic fluid. The measuring device 109 is provided, for example, in the hydraulic oil tank 22, either on the main oil passage 39, the discharge oil passage 40, or on the entry side of the travel control valve 38B. The temperature measured by the measuring device 109 is input to the control device 105.

  The second setting unit 106 makes the opening degree of the travel control valve 38B less than the switching opening degree when the temperature of the measuring device 109 acquired by the control device 105 is equal to or lower than a predetermined temperature. For example, when the operating member 108 is not operated and the temperature measured by the measuring device 109 is 0 ° C. or less, the travel control valve 38B is opened at least the minimum opening M3 and less than the first switching opening M1. Hold or hold the minimum opening degree M3 or more and less than the second switching opening degree M2. Then, when the temperature measured by the measuring device 109 exceeds 10 ° C., the opening control of the travel control valve 38B is stopped. The second setting unit 106 also sets the opening degree of the travel control valve 38B in accordance with the temperature measured by the measuring device 109, as in the first embodiment.

Third Embodiment
FIG. 8 shows a part of a traveling system hydraulic system in the third embodiment. The third embodiment is an example in which the traveling motor is changed, and can be applied to all the embodiments. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.
As shown in FIG. 8, in the third embodiment, the first travel motor device 31L and the second travel motor device 31R are modified. The first travel motor device 31L and the second travel motor device 31R have a travel motor 236, a longitudinal switching valve 235, and a travel control valve (hydraulic switching valve) 38C. Hydraulic fluid can be supplied to the first travel motor device 31L, the second travel motor device 31R, the travel motor 236, the longitudinal switching valve 235, and the travel control valve (hydraulic switching valve) 38C.

  The traveling motor 236 employs a cam motor (radial piston motor). The traveling motor 236 changes rotation and torque of the output shaft by changing the size of the capacity (motor capacity) at the time of operation. Specifically, the traveling motor 236 includes a first motor 236A and a second motor 236B. By driving the first motor 236A and the second motor 236B, the motor displacement is increased, and the travel motor 236 is at the first speed. In addition, by driving any one of the first motor 236A and the second motor 236B, the motor displacement is reduced, and the traveling motor 131 has the second speed.

  The travel control valve 38C is a two-position switching valve that switches between the first position 38a and the second position 38b. The switching operation of the travel control valve 38C is performed by the proportional valve 237. The proportional valve 237 and the travel control valve 38C are connected by a third control oil passage (first oil passage) 286. The third control oil passage 286 is connected to a second oil passage 287 connecting the first oil passage 286 and the hydraulic fluid tank 22. The second oil passage 287 is provided with a throttling portion 288 that reduces the flow rate of the hydraulic oil flowing to the second oil passage 287.

The setting of the opening degree of the proportional valve 237 is performed by the control device 90 having the first setting unit 91. The first setting unit 91 sets the pilot pressure applied to the travel control valve 38C to a pressure lower than the switching pressure of the travel control valve 38C when the operation member is not operated (the operation amount is zero). Further, when the operation member is operated, the first setting unit 91 makes the pilot pressure applied to the travel control valve 38C equal to or higher than the switching pressure based on the command input to the control device 90.
As described above, also in the third embodiment, the pilot pressure applied to the travel control valve 38C is set to a pressure lower than the switching pressure of the travel control valve 38C. Therefore, pilot oil flows from the proportional valve 237 to the first oil passage 286 (third control oil passage), and the pilot oil flows from the first oil passage 286 to the second oil passage 287 and returns to the hydraulic oil tank 22. You can do this by warming up.

Fourth Embodiment
FIG. 9 shows a working hydraulic system in the fourth embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above. The code "X1" shown in FIG. 9 indicates the connection destination of the oil passage.
As shown in FIG. 9, the working hydraulic system includes a first operating valve 120 and a plurality of seventh oil passages 121 a and 121 b. The first operation valve 120 is connected to the middle of the discharge oil passage (fifth oil passage) 40. The first operation valve 120 is a valve capable of changing the pressure of the pilot oil toward the remote control valves (operation valves) 59A, 59B, 59C, 59D. The first operation valve 120 is a two-position switching valve that can be switched between the first position 120a and the second position 120b by excitation. Note that the opening degree of the first operation valve 120 at the second position 120 b can be changed.

The plurality of seventh oil passages 121a and 121b are discharge oil passages 40, and a section 40a between the first operation valve 120 and the remote control valves (operation valves) 59A, 59B, 59C, 59D, and a plurality of sixth oils It is an oil passage connecting the passages 43a, 43b, 43c, 43d. The seventh oil passage 121a connects the section 40a and the sixth oil passages 43a and 43c. The seventh oil passage 121 b connects the section 40 a and the sixth oil passages 43 b and 43 d. A plurality of throttles 124 are provided in the seventh oil passages 121a and 121b.
The control device 90 includes a third setting unit 122 and a storage unit 92. The third setting unit 122 is configured of a program, an electric / electronic circuit and the like incorporated in the control device 90. Hereinafter, for convenience of explanation, the remote control valves (operation valves) 59A, 59B, 59C, 59D will be simply referred to as remote control valves and the explanation will be continued.

  The third setting unit 122 can set the maximum value (upper limit value) of the pilot pressure output from the remote control valve to less than the switching pressure at which the control valve 56 is switched. Specifically, in the state (full stroke) in which the control lever 58 is operated to the maximum, the pilot pressure output from the remote control valve is maximum. Even when the third setting unit 122 excites the first operation valve 120 and opens the first operation valve 120, the maximum value of the pilot pressure output from the remote control valve is less than the switching pressure of the control valve 56. Thus, the opening degree of the first operation valve 120 is set. For convenience of explanation, the maximum value of the pilot pressure output from the remote control valve (the upper limit value of the pilot pressure output from the remote control valve when the control lever 58 is fully stroked) is referred to as the maximum pilot pressure.

The storage unit 92 is a switching pressure at which the first control valve 56A and the second control valve 56B are switched, or the opening degree of the first operation valve 120 corresponding to the switching pressure in a state where the operating lever 58 has a full stroke. A current value corresponding to the opening degree) or the switching opening degree is stored.
Hereinafter, the operation of the third setting unit 122 will be described in detail.
A switch 123 is connected to the control device 90. The switch 123 is an on / off switch that sets whether to permit the operation of the control valve 56. The switch 123 is operated, for example, by raising and lowering a lever (unload) provided around the driver's seat 8. When the lever is raised, the switch 123 is turned on, and when the lever is lowered, the switch 123 is turned off.

  Here, when the switch 123 is on (the operation of the control valve 56 is not permitted) and the operation lever 58 is not operated, the third setting unit 122 performs the first control valve 56A and the second control valve. The pilot pressure acting on the pressure receiving portion 56B is maintained at a pressure lower than the switching pressure. That is, the third setting unit 122 applies a predetermined current to the solenoid 120 c to make the opening degree corresponding to the second position 120 b of the first operation valve 120 larger than zero, and the opening degree is the switching opening degree Less than. That is, the opening degree when the first operation valve 120 is at the second position 120b is set to the minimum opening degree or more and less than the switching opening degree. The minimum opening degree is the minimum opening degree through which the hydraulic oil flows to the fifth oil passage 40 (the seventh oil passage 131) through the first operation valve 120 as in the above-described embodiment.

Further, the third setting unit 122 fully opens the opening degree at the second position when the switch 123 is off (the operation of the control valve 56 is not permitted) and the operation lever 58 is not operated.
As described above, according to the third setting unit 122, the maximum pilot pressure is less than the switching pressure at which the control valve 56 is switched. Therefore, in the state where the operation lever 58 is not operated (under the condition that the operation lever 58 is in the neutral state), the hydraulic oil is discharged from the discharge oil passage 40, the seventh oil passage 121a, 121b, and the sixth oil passage 43a, 43b. , 43c, 43d, and the ports of the remote control valve can flow to the drain oil passage 42 and the hydraulic oil tank 22. Therefore, the hydraulic fluid can be circulated through the discharge oil passage 40, the seventh oil passages 121a and 121b, the sixth oil passages 43a, 43b, 43c and 43d, and the remote control valve, and the warm-up can be easily performed.

  Also in the fourth embodiment, a measuring device for measuring the temperature of the hydraulic oil is provided, and switching of the control valve 56 is performed when the temperature measured by the measuring device is equal to or lower than a predetermined temperature. It may be set to less than the switching pressure. When the temperature measured by the measuring device is 0 ° C. or less, the third setting unit 122 holds the opening degree of the valve corresponding to the second position 120 b below the switching opening degree. When the temperature measured by the measurement device exceeds 10 ° C. and the switch 123 is turned off, the third setting unit 122 fully opens the opening degree of the valve corresponding to the second position 120 b. Further, the third setting unit 122 may also change the opening degree of the valve corresponding to the second position 120b according to the temperature measured by the measuring device, as in the above-described embodiment.

Fifth Embodiment
FIG. 10 shows a travel system hydraulic system according to the fifth embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.
As shown in FIG. 10, the travel system hydraulic system includes a hydraulic device 234, a travel lever 254, a plurality of eighth oil passages 130a and 130b, ninth oil passages 131a and 131b, and a first operation valve 120. ing. The hydraulic device 234 has the same configuration as the hydraulic device 34 described in the first embodiment. The first operation valve 120 is a solenoid valve whose opening degree can be changed by excitation.
The travel lever 254 has the same structure as the travel lever 54 described above, and remote control valves 255A and 255B are provided at the lower portion. The remote control valves 255A, 255B have a discharge port (port) connected to the hydraulic oil tank 22, and are connected to the hydraulic oil tank 22 via the discharge oil passage 42.

  The eighth oil passage 130 a connects the remote control valve 255 A and the pressure receiving portion 53 b of the HST pump 53. The eighth oil passage 130 b connects the remote control valve 255 B and the pressure receiving portion 53 a of the HST pump 53. A throttling portion 133a is provided between the HST pump 53 and the eighth oil passage 130a, which is a connection portion to which the ninth oil passage 131a is connected. Further, a throttling portion 133b is provided also in the eighth oil passage 130b and between the HST pump 53 and the connection portion to which the ninth oil passage 131b is connected.

  The ninth oil passage 131a is an oil passage connecting the discharge oil passage 40 and the eighth oil passage 130a. The ninth oil passage 131 b is an oil passage connecting the discharge oil passage 40 and the eighth oil passage 130 b. Specifically, the ninth oil passage 131a is a discharge oil passage 40, and connects the section 40b between the first operation valve 120 and the remote control valve (operation valve) 255A and the eighth oil passage 130a. The ninth oil passage 131 b connects the section 40 b of the discharge oil passage 40 and the eighth oil passage 130 b.

  The control device 90 includes a fourth setting unit 132 and a storage unit 92. The fourth setting unit 132 is configured of a program incorporated in the control device 90, an electric / electronic circuit, and the like. The storage unit 92 corresponds to an operating pressure which is the lowest pressure at which the HST pump 53 operates and a minimum opening degree and a minimum opening degree of the first operation valve 120 corresponding to the operating pressure when the travel lever 254 is full stroke. The current value to be stored is stored. Hereinafter, for convenience of explanation, the remote control valves 255A and 255B will be simply referred to as remote control valves and the description will be continued. The minimum opening degree is the minimum opening degree through which the hydraulic oil flows to the ninth oil passages 131a and 131b through the first operation valve 120 as in the above-described embodiment.

  The fourth setting unit 132 operates the traveling lever 254 when the setting for warming up is made (for example, when a signal for warming up with a switch or the like is input to the control device 90) In the absence state, the opening degree of the first actuating valve 120 is set to an opening degree not less than a predetermined value (minimum opening degree) and not reaching the maximum pilot pressure. That is, the fourth setting unit 132 sets the maximum pilot pressure (maximum pilot pressure output from the remote control valve when the travel lever 254 is in the full stroke state) not higher than the operating pressure at which the HST pump 53 operates. 1 Open the operating valve 120. That is, the fourth setting unit 132 performs the first operation so that the maximum pilot pressure is less than the operation pressure of the HST pump 53 even in a state where the first operation valve 120 is excited and the first operation valve 120 is opened. The opening degree of the valve 120 is set.

  As described above, according to the fourth setting unit 132, the maximum pilot pressure is set to a pressure lower than the operating pressure at which the hydraulic device 34 operates. Therefore, in the state where the travel lever 254 is not operated (under the condition where the travel lever 254 is in the neutral state), the hydraulic oil is discharged from the discharge oil passage 40, the eighth oil passage 130a, the eighth oil passage 130b, and the remote control valve. It can flow to the discharge oil passage 42 and the hydraulic oil tank 22 through the port. Therefore, the working oil can be circulated through the discharge oil passage 40, the eighth oil passages 130a and 130b, and the remote control valve, and the warm-up can be easily performed.

  In the fifth embodiment as well, a measuring device for measuring the temperature of hydraulic oil is provided, and when the temperature measured by the measuring device is equal to or lower than a predetermined temperature, the HST pump 53 operates the maximum pilot pressure. It may be set to less than the operating pressure. When the temperature measured by the measuring device is 0 ° C. or less, the fourth setting unit 132 holds the opening degree of the first operating valve 120 at less than the operating pressure. When the temperature measured by the measuring device exceeds 10 ° C., for example, the fourth setting unit 132 fully opens the opening degree. Moreover, the 4th setting part 132 may change the opening degree of the 1st action valve 120 according to the temperature measured with the measuring device similarly to embodiment mentioned above.

  Further, the first operation valve 120 described in the fifth embodiment suppresses not only warm-up, but also, for example, the pressure of the hydraulic oil supplied to the remote control valve in order to prevent an engine stall. For example, when the output of the prime mover 32 decreases due to the load of the working system or the like, the first actuation valve 120 is adjusted according to the output of the prime mover 32. The engine stall is prevented by the controller 90. Further, the first operating valve 120 can also suppress the pressure of the hydraulic oil supplied to the remote control valve in order to unload the same as the above-described operating lever 58. For example, as described above, when the switch 123 is on, the opening degree of the first operation valve 120 is set to a predetermined value. For example, when unloading and warming up, the opening degree of the first operation valve 120 is set by the fourth setting unit 132 to the minimum opening degree or more and below the operating pressure as described above. Control of the 1st operation valve 120 other than warming up is not limited to what was mentioned above.

Sixth Embodiment
FIG. 11 shows a traveling system hydraulic system according to the sixth embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.
As shown in FIG. 11, the travel system hydraulic system includes a tenth oil passage (first bypass oil passage) 140 and a second operation valve 141. The tenth oil passage 140 connects the discharge oil passage 40 and the eighth oil passage 130a, and connects the discharge oil passage 40 and the eighth oil passage 130b. The tenth oil passage 140 is branched into two in the middle, and a second bypass oil passage 151 having a throttling portion 150 is connected to the two oil passages 140a after branching. An eighth oil passage 130a is connected to one oil passage 140a after branching. The eighth oil passage 130 b is connected to the other oil passage 140 a after the branching. In one oil passage 140a and the other oil passage 140a, a check valve 152 which allows pilot oil from the HST pump 53 and blocks pilot oil toward the HST pump 53 in the section to which the second bypass oil passage 151 is connected. Is connected. In the tenth oil passage 140, a second operation valve 141 is provided in the oil passage before branching.

The second operating valve 141 can change the pressure of the hydraulic oil directed to the hydraulic device 234 (HST pump 53). The second operation valve 141 is a solenoid valve whose opening degree can be changed by excitation.
The control device 90 includes a fifth setting unit 142 and a storage unit 92. The fifth setting unit 142 is configured of a program incorporated in the control device 90, an electric / electronic circuit, and the like. The storage unit 92 corresponds to the operating pressure which is the lowest pressure at which the HST pump 53 operates, the opening degree (switching opening degree) of the first operating valve 120 corresponding to the operating pressure, and the switching opening degree, as in the embodiment described above. The current value to be stored is stored.

  The fifth setting unit 142 can set the pilot pressure output from the tenth oil passage 140 to less than the operating pressure at which the HST pump 53 operates. The fifth setting unit 142 causes the pilot oil to flow in the tenth oil passage 140 by setting the opening degree of the second operation valve 141 to such an extent that the HST pump 53 does not operate when the travel lever 254 is not operated. On the other hand, when the travel lever 254 is operated, the fifth setting unit 142 closes the second operation valve 141 so that hydraulic oil does not flow to the tenth oil passage 140.

  As described above, according to the fifth setting unit 142, in the state where the travel lever 54 is not operated (under the condition where the travel lever 254 is in the neutral state), hydraulic fluid is discharged from the discharge oil passage 40, the tenth oil passage 140, the tenth The oil passage 130a, the eighth oil passage 130b, and the ports of the remote control valve can flow to the discharge oil passage 42 and the hydraulic oil tank 22. Therefore, the discharge oil passage 40, the eighth oil passages 130a and 130b, and the remote control valve can be easily warmed up.

  Also in the sixth embodiment, a measuring device for measuring the temperature of the hydraulic oil is provided, and when the temperature measured by the measuring device is equal to or lower than a predetermined temperature, the HST pump 53 operates the maximum pilot pressure. It may be set to less than the operating pressure. When the temperature measured by the measurement device is 0 ° C. or less, the fifth setting unit 142 holds the opening degree of the first actuating valve 120 at less than the actuating pressure. When the temperature measured by the measurement device exceeds 10 ° C., for example, the fifth setting unit 142 fully opens the opening degree. The fifth setting unit 142 may also change the opening degree of the first operation valve 120 according to the temperature measured by the measuring device, as in the above-described embodiment.

  FIG. 12 shows a modification of the sixth embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above. As shown in FIG. 12, at least two tenth oil passages (first bypass oil passages) 140 are provided in the traveling system hydraulic system. One tenth oil passage 140 connects the discharge oil passage 40 and the eighth oil passage 130a. The other tenth oil passage 140 connects the discharge oil passage 40 and the eighth oil passage 130b. A throttling portion 151 is provided in one tenth oil passage 140 and the other tenth oil passage 140. As shown in the fifth embodiment, the actuation valve 120 in the modification is also used for anti-stall and unload, and the control of warm-up is not performed.

  According to the modification shown in FIG. 12, when the travel lever 254 is not operated, the hydraulic oil is discharged from the discharge oil passage 40, the tenth oil passage 140, the eighth oil passage 130a, the eighth oil passage 130b, and the remote control valve. It can flow to the discharge oil passage 42 and the hydraulic oil tank 22 through the port. Therefore, the discharge oil passage 40, the eighth oil passages 130a and 130b, and the remote control valve can be easily warmed up.

Seventh Embodiment
FIG. 13 shows a part of the working hydraulic system in the seventh embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.
As shown in FIG. 13, the third control valve 56C is operated by the two switching valves 160A and 160B. The switching valves 160A and 160B are configured by two-position switching valves that can be switched between the first position 160a and the second position 160b. The switching of the switching valves 160A, 160B can be switched by the controller 90. For example, based on the operation of the operation member 93 connected to the control device 90, a signal to be switched from the control device 90 is output to the switching valves 160A and 160B.

A discharge oil passage 40 is connected to one switching valve 160A and the other switching valve 160B. One switching valve 160A and a pressure receiving portion 61a of the third control valve 56C are connected by a first control oil passage 186a. The other switching valve 160B and the pressure receiving portion 61b of the third control valve 56C are connected by a second control oil passage 186b.
The working hydraulic system according to the seventh embodiment includes a third bypass oil passage 161 and a fourth bypass oil passage 162. The third bypass oil passage 161 is an oil passage connecting the inlet side of the one switching valve 160A and the outlet side of the one switching valve 160A, and a throttle portion 163 is provided. In other words, the third bypass oil passage 161 connects the vicinity of the input port of one of the switching valves 160A and the first control oil passage 186a.

The fourth bypass oil passage 162 is an oil passage connecting the inlet side of the other switching valve 160B and the outlet side of the other switching valve 160B, and a throttle portion 164 is provided. In other words, the fourth bypass oil passage 162 connects the vicinity of the input port of the other switching valve 160B and the second control oil passage 186b.
As described above, according to the seventh embodiment, in a state where one of the switching valves 160a is at the first position 160a, the hydraulic oil passes through the discharge oil passage 40 and the third bypass oil passage 161 to the first control oil passage 186a. It flows into the hydraulic oil tank 22 after passing through one of the switching valves 160a. Similarly, in the state where the other switching valve 160b is at the first position 160b, the hydraulic oil passes through the discharge oil passage 40 and the fourth bypass oil passage 162 and enters the second control oil passage 186b, and the other switching valve 160b Flow to the hydraulic oil tank 22. As described above, the hydraulic fluid can be circulated through the discharge fluid channel 40, the bypass fluid channel (third bypass fluid channel 161, the fourth bypass fluid channel 162), and the switching valves 160a and 160b, and the warm-up can be achieved. It can be done easily.

  In the seventh embodiment, although the third control valve 56C has been described, the third control valve 56C may be applied to the other control valves 56 (the first control valve 56A, the second control valve 56B). The hydraulic oil may be circulated by providing a switching valve for operating the control valve 56 and connecting the inlet side and the outlet side of the switching valve with a bypass oil passage.

Eighth Embodiment
FIG. 14 shows a part of a traveling system hydraulic system in the eighth embodiment. The eighth embodiment is a modification of the second embodiment described above. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.
As shown in FIG. 14, the traveling hydraulic system has a fifth bypass oil passage 170 and a sixth bypass oil passage 171. The fifth bypass oil passage 170 is an oil passage connecting the discharge oil passage 40 and the first port (bottom port) of the swash plate switching cylinder 37. That is, the fifth bypass oil passage 170 connects the discharge oil passage 40 and the first supply / discharge oil passage 100a. A narrowed portion 172 is provided in the fifth bypass oil passage 170.

Further, the sixth bypass oil passage 171 is an oil passage connecting the discharge oil passage 40 and the second port (rod port) of the swash plate switching cylinder 37. That is, the sixth bypass oil passage 171 connects the discharge oil passage 40 and the second supply / discharge oil passage 100b. A throttle portion 173 is provided in the sixth bypass oil passage 171.
As described above, according to the eighth embodiment, in the state where the travel control valve 38B is at the third position (neutral position) 38c, the hydraulic fluid passes through the discharge oil passage 40 and the fifth bypass oil passage 170 to perform the first supply and discharge. The oil enters the oil passage 100a, passes through the travel control valve 38B, and flows to the hydraulic oil tank 22. Similarly, in a state where the travel control valve 38B is at the third position (neutral position) 38c, the hydraulic oil passes through the discharge oil passage 40 and the sixth bypass oil passage 171 and enters the second oil supply / discharge oil passage 100b and travels It flows to the hydraulic oil tank 22 through the control valve 38B. Thus, the hydraulic oil can be circulated through the discharge oil path 40, the bypass oil path (the fourth bypass oil path 170, the fifth bypass oil path 171), the travel control valve 38B, and the warm-up can be simplified. Can be done.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is indicated not by the above description but by the claims, and is intended to include all the modifications within the meaning and scope equivalent to the claims.

1 Working machine 22 tank (hydraulic oil tank)
32 prime mover 43a, 43b, 43c 43d sixth oil passage 56 control valve 55 operation valve 59 operation valve 60 proportional valve 86 first oil passage 87 second oil passage 91 first setting portion 93 operation member 95 measuring device 100 third oil passage 101 fourth oil passage 106 second setting unit 121 a, 121 b seventh oil passage 122 third setting unit 130 a, 130 b eighth oil passage 131 a, 131 b ninth oil passage 132 fourth setting unit 142 fifth setting unit 140 tenth oil Road

Claims (9)

A hydraulic pump that discharges hydraulic oil,
A tank for storing hydraulic oil,
Operation member,
An operating valve whose pilot pressure, which is the pressure of hydraulic fluid to be output according to the operation of the operating member, can be set and which has a port connected to the tank;
A fifth oil passage connecting the operation valve and the hydraulic pump;
A first operation valve connected to the fifth oil passage and capable of changing the pressure of the hydraulic oil directed to the operation valve;
A control valve capable of switching the flow direction of hydraulic fluid by the pilot pressure set by the operation valve;
A sixth oil passage connecting the operation member and the control valve;
A seventh oil passage connecting the fifth oil passage and the sixth oil passage;
A third setting unit capable of setting the maximum value of the pilot pressure output from the operation valve to be less than the switching pressure at which the control valve is switched by setting the pressure of the hydraulic oil of the first operation valve to a predetermined value When,
The hydraulic system of the working machine that is equipped with. A hydraulic pump that discharges hydraulic oil,
A tank for storing hydraulic oil,
Operation member,
An operating valve whose pilot pressure, which is the pressure of hydraulic fluid to be output according to the operation of the operating member, can be set and which has a port connected to the tank;
A fifth oil passage connecting the operation valve and the hydraulic pump;
A first operation valve connected to the fifth oil passage and capable of changing the pressure of the hydraulic oil directed to the operation valve;
A hydraulic device operable by the pilot pressure set by the control valve;
An eighth oil passage connecting the operation valve and the hydraulic device;
A ninth oil passage connecting the eighth oil passage and a section of the fifth oil passage between the operation valve and the first operation valve;
A fourth setting unit capable of setting the maximum value of the pilot pressure output from the operation valve to be lower than the operating pressure at which the hydraulic device operates by setting the pressure of the hydraulic oil of the first operating valve to a predetermined value;
The hydraulic system of the working machine that is equipped with. A hydraulic pump that discharges hydraulic oil,
A tank for storing hydraulic oil,
Operation member,
An operating valve whose pilot pressure, which is the pressure of hydraulic fluid to be output according to the operation of the operating member, can be set and which has a port connected to the tank;
A fifth oil passage connecting the operation valve and the hydraulic pump;
A hydraulic device operable by the pilot pressure set by the control valve;
An eighth oil passage connecting the operation valve and the hydraulic device;
A tenth oil passage connecting the eighth oil passage and the fifth oil passage;
A second operation valve connected to the tenth oil passage and capable of changing the pressure of the hydraulic oil directed to the hydraulic device;
A fifth setting unit configured to set the pressure of the hydraulic oil by the second operating valve to less than the operating pressure at which the hydraulic device operates;
The hydraulic system of the working machine that is equipped with. A measuring device for measuring the temperature of the hydraulic fluid;
The third setting unit outputs the pressure of the hydraulic oil of the first operation valve to a predetermined value when the temperature measured by the measurement device is equal to or lower than a predetermined temperature. The hydraulic system of a working machine according to claim 1, wherein the maximum value of the pilot pressure is maintained below the switching pressure at which the control valve is switched. A measuring device for measuring the temperature of the hydraulic fluid;
The fourth setting unit outputs the pressure of the hydraulic oil of the first operation valve to a predetermined value when the temperature measured by the measurement device is equal to or lower than a predetermined temperature. 3. The hydraulic system of a working machine according to claim 2, wherein the maximum value of the pilot pressure is maintained below the operating pressure at which the hydraulic system operates. A measuring device for measuring the temperature of the hydraulic fluid;
The fifth setting unit holds the pressure of the hydraulic oil by the second operating valve below the operating pressure at which the hydraulic device operates when the temperature measured by the measuring device is equal to or lower than a predetermined temperature. The hydraulic system of the working machine according to claim 3. A switch for setting whether or not to permit switching of the control valve;
The third setting unit sets the pressure of the hydraulic oil of the first operation valve to a predetermined value when the switching of the control valve is not permitted and the operation of the operation member is not performed. The work machine according to claim 1 or claim 2, wherein the maximum value of the pilot pressure is maintained below the switching pressure, and the maximum value of the pilot pressure is maintained above the switching pressure when switching of the control valve is permitted. Hydraulic system.   When the operation member is not operated, the fourth setting unit sets the pressure of the hydraulic oil of the first operation valve to a predetermined value and holds the pressure less than the operation pressure at which the hydraulic device operates. The hydraulic system of a working machine according to claim 2 or 5, wherein when the operation member is operated, the hydraulic pressure is maintained at or above an operating pressure at which the hydraulic device operates.   When the operation member is not operated, the fifth setting unit sets the pressure of the hydraulic oil of the second operation valve to a predetermined value and holds the pressure less than the operation pressure at which the hydraulic device operates. The hydraulic system of a working machine according to claim 3 or 6, wherein, when the operation member is operated, the hydraulic pressure is maintained at or above an operating pressure at which the hydraulic device operates.

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