JP2024082359A - Work vehicles - Google Patents

Abstract

To suppress generation of work unevenness in a work machine even when a change in inclination of a travel vehicle body is large, as compared to a conventional configuration.SOLUTION: A work vehicle comprises a control unit (200). The control unit (200) controls lifting up and down of a work machine (18) according to a position of a cover part (18a) and causes the work machine (18) to lift up and down at a low speed when an amount of change of the cover part (18a) is larger than a predetermined threshold, as compared to when the amount of change is smaller than the threshold, so that even when a change in inclination of a travel body (1a) is large, generation of work unevenness in the work machine (18) can be suppressed.SELECTED DRAWING: Figure 5

Description

This invention relates to work vehicles such as tractors, seedling transplanters, and lawnmowers.

A technology is known in which a work vehicle such as a tractor or seedling transplanter is provided with a rear cover sensor that detects the rotation angle of a rear cover that covers the rear of a work machine such as a rotary tiller, and the work machine is raised or lowered according to the rotation angle of the rear cover, thereby controlling the height of the work machine relative to the ground, such as the tilling depth, to remain constant even if the traveling vehicle body tilts forward or backward due to unevenness in the ground (Patent Document 1).

Japanese Patent Application Laid-Open No. 8-289609

In the conventional technology described in Patent Document 1, the work implement is raised and lowered after the rotation of the rear cover is detected, so there is a delay in raising and lowering the work implement in response to unevenness in the field. Therefore, when there is a large change in the inclination of the traveling vehicle body, the work implement and rear cover also rise and fall greatly, but in response to large unevenness in the field, the work implement rises and falls greatly with a delay. This creates a problem in that unevenness (uneven work) is easily generated in the finished work.

The technical objective of the present invention is to suppress the occurrence of uneven work by the work machine even when there is a large change in the inclination of the traveling vehicle body, compared to conventional configurations.

The above object of the present invention is achieved by the following means.
The invention described in claim 1 is a work vehicle (1) comprising: a running body (1a); a work machine (18) supported on the running body (1a) so as to be able to rise and fall and performing work on a field, the work machine (18) having a cover portion (18a) that moves according to the depth of the work; a cover sensor (SN0) that detects the position of the cover portion (18a); and a control unit (200) that controls the raising and lowering of the work machine (18) according to the position of the cover portion (18a), wherein when the amount of change in the cover portion (18a) is greater than a predetermined threshold value, the control unit (200) raises and lowers the work machine (18) at a slower speed than when the amount of change is smaller than the threshold value.

The invention described in claim 2 is the work vehicle (1) described in claim 1, characterized in that it is provided with the control unit (200) that raises and lowers the work implement (18) at a lifting and lowering speed when the amount of change in the cover portion (18a) is greater than the threshold value and the engine (E) rotation speed does not reach a predetermined rotation speed.

According to the invention described in claim 1, compared to the conventional configuration in which the work machine is raised and lowered at a constant speed regardless of the amount of change in the cover part, by raising and lowering the work machine (18) at a slower speed when the amount of change in the cover part (18a) is large compared to when the amount of change is small, it is possible to suppress the occurrence of uneven work in the work machine (18) even when there is a large change in the inclination of the traveling body (1a).
According to the invention described in claim 2, in addition to the effects of the invention described in claim 1, even if the amount of change in the cover portion (18a) is large, if the rotation speed of the engine (E) does not reach a predetermined rotation speed, the working machine (18) is quickly raised and lowered, thereby preventing the engine (E) under load from stopping.

FIG. 1 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment of the present invention, and is an explanatory diagram of a state in which a work implement is lowered to a height at which the work implement can be used. FIG. 2 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment, with the work implement in a raised state. FIG. 3 is a functional block diagram of the control unit according to the embodiment. FIG. 4 is an explanatory diagram of the relationship between the position of the lift lever and the height of the work machine according to the embodiment. FIG. 5 is an explanatory diagram of a flow chart of the work machine lifting and lowering process according to the embodiment.

FIG. 1 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment of the present invention, and is an explanatory diagram of a state in which a work implement is lowered to a height at which the work implement can be used.
FIG. 2 is an explanatory diagram of a tractor as an example of a work vehicle according to an embodiment, with the work implement in a raised state.
1 and 2, a tilling tractor 1 as an example of a work vehicle of the present invention is equipped with front wheels 2, 2 and rear wheels 3, 3 at the front and rear of a traveling body 1a, and is configured so that the rotational power of an engine E mounted in an engine room 4 at the front of the traveling body is appropriately reduced by a speed change device in a transmission case 5 and transmitted to the front wheels 2, 2 and the rear wheels 3, 3. The engine room 4 is configured to be covered by a bonnet 6. A working machine such as a tiller 18 for tilling the ground (field) behind the tractor 1 is attached to the rear of the body of the tractor 1, and power is transmitted through a rear PTO shaft 141 to drive the working machine.
In this specification, the left and right sides in the forward direction of the tractor 1 are referred to as the left and right sides, respectively, and the forward direction is referred to as the front side and the reverse direction is referred to as the rear side.

A cabin 7 is supported on the top of the traveling vehicle body 1a. Inside the cabin 7, a driver's seat 8 is located above the transmission case 5, and in front of the driver's seat 8, a steering wheel 10, a parking brake (not shown), etc. are arranged. Also in front of the driver's seat 8, a display panel including a speedometer (not shown), various operation switches (not shown), etc. are arranged. In the front lower part of the driver's seat 8, driving operation tools such as a brake pedal 12 and an accelerator pedal 13 having a forward pedal and a reverse pedal are arranged.

In FIG. 1, a hydraulic cylinder case 14 is provided above the rear of the transmission case 5, and lift arms 15, 15 are pivotally attached to both the left and right sides of this hydraulic cylinder case 14. Lift rods 17, 17 are interposed and connected between the lift arms 15, 15 and lower links 16, 16, and a tiller 18, an example of a working machine, is connected to the rear of the lower links 16, 16.

When hydraulic oil is supplied to the hydraulic cylinder 14a housed in the hydraulic cylinder case 14, the lift arms 15, 15 are rotated upward, and the work machine (cultivator) 18 is raised via the lift rod 17, lower link 16, etc. Conversely, when the hydraulic oil in the hydraulic cylinder 14a is discharged into the transmission case 5, which also serves as the hydraulic tank, the lift arms 15, 15 are lowered.

A rear cover 18a, which is an example of a cover portion, is disposed at the rear of the tiller 18. The rear cover 18a is supported movably (rotatably and vertically movable) about a rotation center 18b relative to a frame portion (not shown) of the tiller 18. A cover sensor SN0 that detects the position of the rear cover 18a is disposed near the rotation center 18b.
The cover sensor SN0 can be fixed to the frame of the working machine 18 by bolting or the like, but is not limited to this. For example, it can be configured to be removable without tools, such as by using a magnet or a snap-in type. By configuring the sensor to be easily removable, the same sensor can be easily continued to be used even if the working machine 18 is replaced due to wear and tear, and the occurrence of individual differences in sensing can be suppressed. In addition, in the case of a configuration that is easily removable, the sensor can be removed when washing the tractor 1, and damage to the sensor can also be prevented.

A position sensor SN1 is disposed at the base end of the lift arm 15 to detect the tilt angle of the lift arm 15, i.e., the height (vertical position) of the working implement 18. Note that the working implement mounted on the rear of the traveling body 1a, i.e., the working implement to which drive is transmitted from the rear PTO shaft 141, is not limited to rotary tilling equipment for agricultural work, but may include plows, seed sowing machines, seedling transplanters, fertilizer spreaders, chemical sprayers, etc.

(Explanation of the control unit of the work vehicle)
FIG. 3 is a functional block diagram of the control unit according to the embodiment.
The tractor 1 of the embodiment has a control unit 200 that controls each function. The control unit 200 has an input/output interface I/O that performs input and output of signals with the outside. The control unit 200 also has a ROM (read-only memory) in which programs and information for performing necessary processing are stored. The control unit 200 also has a RAM (random access memory) for temporarily storing necessary data. The control unit 200 also has a CPU (central processing unit) that performs processing according to the programs stored in the ROM or the like. Therefore, the control unit 200 of the embodiment is configured by a small information processing device, a so-called microcomputer. Therefore, the control unit 200 can realize various functions by executing programs stored in the ROM or the like.

Signals are input to the control unit 200 from signal input elements such as a cover sensor SN0, a position sensor SN1, an engine RPM sensor SN2, a lift lever 211, an auto button 212, and various other sensors (not shown).
The control unit 200 outputs control signals to the hydraulic cylinder 14a and other controlled elements (not shown).

The control unit 200 according to the embodiment has the following functional means (program modules).
The work machine height detection means 201 detects the height of the work machine 18 based on the detection result of the position sensor SN1.
The cover position detection means 202 detects the position (rotational position) of the rear cover 18a based on the detection result of the cover sensor SN0.
The engine speed detection means (engine load detection means) 203 detects the speed of the engine E based on the engine speed sensor SN2. That is, when the engine E is driven at a constant speed, such as when the work machine 18 is in operation, the engine load applied to the engine E can be detected by detecting the engine speed of the engine E.

The change amount determination means 204 determines whether the amount of change of the rear cover 18a reaches a predetermined first threshold (change amount threshold). The change amount determination means 204 in the embodiment calculates the difference between the position at the time of the previous detection and the position at the time of the current detection as the amount of change based on the position of the rear cover 18a detected at a predetermined time interval, and determines whether the amount of change reaches the change amount threshold.
The rotation speed determination means 205 determines whether the rotation speed of the engine E reaches a predetermined second threshold (rotation speed threshold). The rotation speed determination means 205 in the embodiment determines whether the current rotation speed of the engine E is lower than the second threshold, with the second threshold being used to determine whether there is a risk of the engine stopping (engine stalling).

The working machine lifting control means 206 controls the height of the working machine 18 based on the height of the rear cover 18a. In other words, in response to the rear cover 18a moving up and down in response to the unevenness of the field, the hydraulic cylinder 14a is controlled to raise and lower the working machine 18 and control the height of the working machine 18 so that the working depth (working height) is constant.

In the tractor 1 of the embodiment, a lift lever 211 is provided inside the cabin 7, and when the lift lever 211 is operated, the working implement 18 can be raised or lowered, and when the auto button 212 for the auto work mode is input, an auto work mode is executed in which work is automatically performed at a constant working depth while the tractor 1 is travelling at a constant speed. Then, when the auto work mode is started, the working implement lift control means 206 controls the height of the working implement 18 so that the working depth is constant according to the height of the rear cover 18a.
It is preferable that the on/off status of the automatic operation mode be indicated on a panel inside the cabin 7.

FIG. 4 is an explanatory diagram of the relationship between the position of the lift lever and the height of the working machine according to the embodiment.
The working machine lifting control means 206 of the embodiment stores not only the lower limit position (lowest position) and upper limit position (highest position) of the height of the tiller (working machine) 18, but also the height of the working machine 18 that is the reference during work. In Fig. 4, the tractor 1 is parked on the flat ground of the field, and the working machine 18 is lowered until the rear cover 18a touches the ground, which is the ground contact position (point A), and the position of the lift lever 211 in this state is the ground contact operation position (point A'), which are stored in advance in correspondence with the detection result of the cover sensor SN0. Next, the working machine 18 and the rear cover 18a are lifted, and at the position (deepest position, point B) of the rear cover 18a at the deepest position where the working machine 18 can work (slightly above the lower part of the chain case in a rotary tiller), the position of the lift lever 211 in this state (deepest operation position, point B') and the detection result of the cover sensor SN0 are stored in advance. The deepest position (point B) can be set to the lowest position in the automatic operation mode. In the automatic operation mode, control can be performed based on the deepest position (point B).

In the conventional configuration, the position of the rear cover 18a can be adjusted by adjusting the length and tension of the cable connected to the rear cover 18a. However, even if the work machine 18 is replaced or replaced due to wear or malfunction, if the deepest position (point B) and ground contact position (point A) are stored and registered in advance, the auto work mode function can be used based on the detection results of the cover sensor SN0 without adjusting the cable.
If points A, B, A', and B' have not been registered or set, it is possible to display a message to that effect (for example, a flashing message) on a panel inside the cabin 7.

Furthermore, the work implement lifting/lowering control means 206 in this embodiment lifts and lowers the work implement 18 at a predetermined first lifting/lowering speed (normal speed) when the amount of change in the rear cover 18a does not reach the amount of change threshold.
Furthermore, in the embodiment, when the change in the rear cover 18a reaches the change amount threshold, the work machine lifting/lowering control means 206 raises and lowers the work machine 18 at a second lifting/lowering speed (low speed) that is slower than the first lifting/lowering speed (normal speed).
In addition, in the embodiment, the work machine lifting/lowering control means 206 raises and lowers the work machine 18 at the first lifting speed (normal speed) if the change in the rear cover 18a reaches the change amount threshold but the engine E rotation speed does not reach the rotation speed threshold.

(Flowchart explanation)
Next, the processing of the tractor 1 according to the embodiment will be described with reference to a flow chart.
Various processes of the tractor 1 other than those described in the flowchart are processed in parallel, and detailed explanations and illustrations thereof will be omitted.

(Description of Work Lifting and Lowering Process of Tractor 1)
FIG. 5 is an explanatory diagram of a flow chart of the work machine lifting and lowering process according to the embodiment.
The process of FIG. 5 begins when the tractor 1 is started.
5, it is determined whether or not an input operation for performing a task has been performed. If the answer is yes (Y), the process proceeds to ST2, and if the answer is no (N), ST1 is repeated.
In ST2, the following steps (1) to (3) are executed, and then the process proceeds to ST3.
(1) Detect the height of the work implement 18.
(2) Detect the height of the rear cover 18a.
(3) Detect the rotation speed of the engine E.

In ST3, the amount of change in the rear cover 18a is calculated, and then the process proceeds to ST4.
In ST4, it is determined whether the amount of change in the rear cover 18a reaches the change amount threshold value. If yes (Y), proceed to ST5, and if no (N), proceed to ST6.
In ST5, it is determined whether the engine speed reaches the speed threshold value. If the answer is no (N), the process proceeds to ST6, and if the answer is yes (Y), the process proceeds to ST7.
In ST6, the lifting/lowering speed of the work machine 18 is set to a first lifting/lowering speed (normal speed), and the process then proceeds to ST8.

In ST7, the lifting/lowering speed of the work implement 18 is set to a second lifting/lowering speed (low speed), and the process then proceeds to ST8.
In ST8, the work machine 18 is moved according to the height of the rear cover 18a. Then, the process proceeds to ST9.
In ST9, it is determined whether the work is completed. If the answer is no (N), the process returns to ST2, and if the answer is yes (Y), the process returns to ST1.

(Operation of the embodiment)
In the tractor 1 according to the embodiment having the above-described configuration, when the amount of change in the rear cover 18a does not reach the amount of change threshold, i.e., when the unevenness of the field surface is small, the lifting and lowering speed of the implement 18 is controlled to a normal speed. Therefore, the implement 18 moves quickly in response to the unevenness of the field, making it possible to maintain a constant working depth (cultivation depth).
On the other hand, when the amount of change in the rear cover 18a reaches the change amount threshold, i.e., when the unevenness of the field surface is large, the lifting and lowering speed of the working implement 18 is controlled to a low speed. In other words, the sensitivity of the lifting and lowering of the working implement 18 is controlled to a state in which it is insensitive to the unevenness. Therefore, compared to when the working implement 18 is raised and lowered at a normal speed for large unevenness in the field, the lifting and lowering speed of the working implement 18 is slower, and the unevenness of the tilled marks when the rear cover 18a comes into contact with the field surface and is leveled is likely to be smaller. Therefore, the tilled marks are likely to be in a smooth state, and the occurrence of uneven work is suppressed.

In the embodiment, the time interval at which the cover sensor SN0 performs detection is kept constant, and the lifting speed is changed to switch between sensitivity and insensitivity to unevenness, but this is not limiting. For example, it is possible to configure the cover sensor SN0 to be sensitive by increasing the frequency at which it performs detection (shortening the time interval), and to be insensitive by decreasing the frequency (lengthening the time interval). In addition, it is also possible to keep the frequency of detection constant, while using less frequent data when calculating the amount of change, for example, by using only every other data.

In addition, in the tractor 1 of the embodiment, even if the change amount of the rear cover 18a reaches the change amount threshold, if the rotation speed of the engine E does not reach the rotation speed threshold, the lifting speed of the working machine 18 is controlled to the normal speed. For example, when the traveling body 1a changes its posture in a large uneven field, the traveling body 1a may rise at the front, causing the working machine 18 to penetrate deep into the ground. In this case, the load to rotate the working machine 18 increases, the load on the engine E also increases, and the rotation speed of the engine E decreases. In this state, if the working machine 18 deep in the ground is raised at a low speed, there is a high possibility that the engine E will stop (the engine will stall) during the lift. Accordingly, in the embodiment, if the rotation speed of the engine E does not reach the rotation speed threshold, the working machine 18 is raised at the normal speed. Therefore, when the load on the engine E increases, the working machine 18 rises quickly, and the occurrence of engine stall is suppressed.

In the embodiment, a configuration has been exemplified in which, when the load on the engine E is high, the work machine 18 is controlled at normal speed not only when ascending but also when descending, but it is also possible to control the work machine 18 at normal speed only when ascending.
In addition, while the configuration has been exemplified in which the lifting and lowering control of the work implement 18 is controlled at the normal speed when the load on the engine E is high, the present invention is not limited to this. For example, if the load on the engine E decreases while the lifting and lowering control of the work implement 18 is being performed at the normal speed (if the rotation speed of the engine E exceeds the rotation speed threshold), it is also possible to control the lifting and lowering control of the work implement 18 to switch to a low speed from that point on.

REFERENCE SIGNS LIST 1 Tractor 1a Traveling vehicle body 2 Front wheels 3 Rear wheels 4 Engine compartment 5 Transmission case 6 Bonnet 7 Cabin 8 Driver's seat 10 Steering handle 12 Brake pedal 13 Accelerator pedal 14 Hydraulic cylinder case 14a Hydraulic cylinder 15 Lift arm 16 Lower link 17 Lift rod 18 Work machine, cultivator 18a Rear cover 18b Rotation center 141 Rear PTO shaft 200 Control unit 201 Detection means 202 Cover position detection means 203 Engine speed detection means (engine load detection means)
204: Change amount determination means 205: Rotation speed determination means 206: Work machine lift control means 211: Lift lever 212: Auto button E Engine SN0: Cover sensor SN1: Position sensor SN2: Rotation speed sensor

Claims (2)

A traveling vehicle body (1a),
a working machine (18) supported on the traveling vehicle body (1a) so as to be capable of ascending and descending and performing work on a farm field, the working machine (18) having a cover part (18a) that moves according to the depth of work;
A cover sensor (SN0) that detects the position of the cover portion (18a);
a control unit (200) that controls elevation of the working machine (18) in accordance with the position of the cover portion (18a), and when an amount of change in the cover portion (18a) is greater than a predetermined threshold, the control unit (200) raises and lowers the working machine (18) at a slower speed than when the amount of change is less than the threshold;
A work vehicle (1) comprising: when the change amount of the cover portion (18a) is greater than the threshold value and the rotation speed of the engine (E) does not reach a predetermined rotation speed, the control portion (200) raises and lowers the working machine (18) at a raising and lowering speed when the change amount is smaller than the threshold value;
A work vehicle (1) according to claim 1, characterized in that it comprises:

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