JP7490198B2 - Travel control device for farm management device and farm management device equipped with same - Google Patents

Description

The present invention relates to an automatic steering type field management device, and in particular to a driving control device in a field management device that can stabilize driving conditions in fields such as sloping fields where control is likely to be unreliable for automatic steering, and a field management device equipped with the same. Hereinafter, in this specification, tea field, rice paddies and fields where crops are grown, vegetable gardens, etc. will be collectively referred to as field.

For example, self-propelled tea plantation management devices that automate the plucking of tea leaves in tea plantations and the reaping of leaves for leaf growth management are becoming more and more popular. The basic structure of this device is that a crawler-equipped running device is installed on the lower part of the leg frame, which is part of a front-viewing frame, so that it can run across the tea ridges, and a management unit such as a plucking machine is mounted in a position facing the tea ridge surface, and the desired management work is performed.
In the current operational situation, workers are on board to manage the work, but most of them are equipped with automatic steering devices, and the situation where the worker steers is limited to changing direction at the edge of the furrow, so-called headland.

As shown in Fig. 6, the travel control device 7' of such a self-propelled tea garden management device is equipped with hydraulic circuits including travel motors 72L', 72R' for driving crawlers and a variable displacement hydraulic pump 71' for the HST on the left and right, forming HST (hydrostatic transmission) 7L', 7R'. By providing bypass circuits 73L', 73R' to the HST 7L', 7R', a part of the hydraulic oil supplied from the variable displacement hydraulic pump 71' to the travel motors 72L', 72R' is released to the bypass circuits 73L', 73R' to control the rotation of the travel motors 72L', 72R' and steer the tea garden management device.
For this control, a plate-shaped tea ridge sensor that comes into contact with the tea ridges is provided at the bottom of the tea garden management device so that it can rotate freely, and when this sensor detects the state in which it is in contact with the tea ridges (rotating state), it controls the supply of hydraulic oil to the left and right travel motors 72L', 72R', and makes the travel device travel along the tea ridges (see, for example, Patent Document 1).

Furthermore, in order to perform such control more accurately, the applicant developed a method using electromagnetic proportional valves 751L', 751R' to open and close bypass circuits 73L', 73R' according to the rotational state of the tea ridge sensor, and this method has been well received by users (see, for example, Patent Document 2).

The above technology will be explained using Figures 1 and 6. When the tea ridge-spanning tea garden management device 1' moves forward, the electromagnetic proportional valves 751L' and 751R' in Figure 6 are fully closed. In this state, the speed of the traveling devices 21L' and 21R' is determined by the control device C' based on the input values of the tea ridge sensors 6R', 6L', the parking switch 25', the tilt sensor 24', and the neutral detection sensor 28', and the opening degree of the electromagnetic proportional valves 751L' and 751R' is determined. This controls the amount of hydraulic oil passing through the bypass circuits 73L' and 73R'.

If the control device C' determines from the detection values of the tea ridge sensors 6L', 6R' that the tea ridges T are straight and that the tea ridge-spanning tea garden management device 1' is moving straight while maintaining an appropriate distance from the tea ridges T, then the opening of the electromagnetic proportional valves 751L', 751R' is set to 0% (fully closed) since there is no need for the HSTs 7L', 7R' to release hydraulic oil to the bypass circuits 73L', 73R'.

On the other hand, if the control device determines from the detection values of the tea ridge sensors 6R', 6L' that the tea ridge T is bent or that the tea ridge-spanning tea garden management device 1' is biased toward the tea ridge T, the speed of the travel motor 72L' on the side where the tea ridge-spanning tea garden management device 1' is to be turned (the left side in this example) is reduced, and the opening degree of the electromagnetic proportional valve 751L' is determined (for example, 80%) to release hydraulic oil to the bypass circuit 73L' in the HST 7L'. Then, when the electromagnetic proportional valve 751L' is set to the desired opening degree, the rotation speed of the travel motor 72L' decreases by the amount of hydraulic oil released to the bypass circuit 73L', and the speed of the travel device 21L' decreases, so that the tea ridge-spanning tea garden management device 1' turns left.

However, when looking at the actual conditions of tea plantations, not all of them are necessarily flat; many tea plantations have ridges arranged along the slope of a hill.
Therefore, with regard to the left-right tilt of the tea field management device, the potentiometer value of the tea ridge sensor is corrected according to the tilt detected by the tilt sensor, and the opening of the proportional solenoid valve is made appropriate.

On the other hand, when it comes to the inclination of the tea farm management device in the forward and backward directions, the load on the travel motor differs depending on whether the device is traveling uphill or downhill on a slope, which can result in the amount of hydraulic oil released into the bypass circuit not being as desired.

That is, based on the detection values of the tea ridge sensors 6L', 6R' (such as the degree of curvature of the tea ridge-straddling type tea garden management device 1'), the opening of the electromagnetic proportional valves 751L', 751R' is adjusted to correct the traveling direction of the tea ridge-straddling type tea garden management device 1'. However, in this opening state, if the load on the traveling motors 72L', 72R' increases due to upward traveling, for example, the pressure difference (P0-P1) of the hydraulic oil before and after the traveling motors 72L', 72R' increases, and the amount of hydraulic oil flowing into the bypass circuits 73L', 73R' increases. As a result, the amount of hydraulic oil supplied to the traveling motors 72L', 72R' decreases, and the speed of the traveling devices 21L', 21R' (crawlers) becomes slower than the desired value. (Here, the pressure of the hydraulic oil between the variable displacement hydraulic pump 71' and the oil inlet side of the travel motors 72L', 72R' is defined as P0, and the pressure of the hydraulic oil between the oil outlet side of the travel motors 72L', 72R' and the variable displacement hydraulic pump 71' is defined as P1.)
On the other hand, when the load on the travel motors 72L', 72R' decreases due to downward travel, the pressure difference (P0-P1) of the hydraulic oil before and after the travel motors 72L', 72R' decreases, reducing the amount of hydraulic oil flowing through the bypass circuits 73L', 73R'. As a result, the amount of hydraulic oil supplied to the travel motors 72L', 72R' increases, causing the speed of the travel devices 21L', 21R' (crawlers) to increase above the desired value.

The difference in the load on the travel motor when ascending or descending on a slope can result in over- or under-control, leading to insufficient correction, causing the tea farm management device to run in extreme meandering directions or, in severe cases, going off track.

Japanese Patent Application Laid-Open No. 9-322628 JP 2005-21127 A

The present invention was made with this background in mind, and the technical objective was to develop a driving control device for a new field management device that can perform accurate automatic driving even in fields located on sloping ground, as well as a field management device equipped with the same.

In other words, the travel control device in the field management device described in claim 1 is a travel control device in a field management device in which a cultivator unit is attached to a travel device that uses a pair of left and right crawlers as a travel body, and travels across ridges to perform the desired field management, and each of the travel devices is driven by hydraulic oil supplied from an HST pump, and the travel motor that drives the travel device is supplied with hydraulic oil from separate left and right hydraulic circuits, and each hydraulic circuit is provided with a bypass circuit that short-circuits part of the hydraulic oil from the HST pump without acting on the travel motor, and is equipped with a flow rate adjustment mechanism to keep the flow rate through the bypass circuit constant regardless of the travel load.

The travel control device in the farm management device described in claim 2 is characterized in that, in addition to the above requirements, the flow control mechanism is a pressure-compensated electromagnetic proportional flow control valve.

Furthermore, the driving control device in the farm management device described in claim 3 is characterized in that, in addition to the requirements described in claim 2, the flow rate of the hydraulic oil passing through the bypass circuit can be controlled only by a control signal from a control device that detects a sensor signal.

The driving control device in the farm management device described in claim 4 is characterized in that, in addition to the requirements described in claims 1, 2, and 3, a check valve is installed downstream of the flow path of the flow control mechanism provided in the bypass circuit.

The driving control device in the farm management device described in claim 5 is characterized in that, in addition to the requirements described in claim 4, the flow rate adjustment mechanism and the check valve are integrated.

Furthermore, the travel control device in the farm management device described in claim 6 is characterized in that, in addition to the requirements described in any one of claims 1, 2, 3, 4, and 5, a parking brake bypass circuit equipped with a valve for short-circuiting the hydraulic oil from the HST pump without applying it to the travel motor is provided in parallel with the bypass circuit equipped with the flow rate adjustment mechanism.

Furthermore, the driving control device in the farm management device described in claim 7 is characterized in that, in addition to the requirements described in claim 5, the flow rate adjustment mechanism is integrated with the check valve and the parking brake control valve provided in the parking brake bypass circuit.

Furthermore, a farm management device equipped with a travel control device according to claim 8 is characterized in that it comprises the travel control device according to any one of claims 1 to 7.
The above problems are solved by the configurations of the inventions described in each of these claims.

First, according to the invention described in claim 1, even if the load on the travel motor fluctuates and the pressure before and after the bypass circuit fluctuates, the flow rate of hydraulic oil flowing to the travel motor is kept constant, so the speed of the travel device can be set to the desired speed.

According to the invention described in claim 2, the flow rate through the bypass circuit can be kept constant with good responsiveness by using a pressure-compensated electromagnetic proportional flow control valve. In addition, a bypass circuit equipped with a flow control mechanism can be easily constructed.

Furthermore, according to the invention described in claim 3, the flow rate of the bypass circuit can be controlled only by the control signal from the control device, so sensitivity adjustment during automatic steering can be easily performed. Also, by making the control signal from the control device different, it becomes possible to attach the flow rate adjustment mechanism to other aircraft, enabling common use.

Furthermore, according to the invention described in claim 4, when the operator operates the vehicle in reverse while the vehicle is automatically steered forward, it is possible to prevent hydraulic oil from flowing back into the flow control mechanism and interfering with reverse movement.

Furthermore, according to the invention described in claim 5, the number of parts that make up the hydraulic circuit can be reduced, resulting in reduced costs and reduced installation space.

Furthermore, according to the invention described in claim 6, since the pressure-compensated electromagnetic proportional flow control valve (electromagnetic proportional flow priority valve) can only control in one direction, by configuring it in this way, it becomes possible to apply the parking brake when reversing.

Furthermore, according to the invention described in claim 7, the number of parts that make up the hydraulic circuit can be reduced, resulting in reduced costs and reduced installation space.

Furthermore, according to the invention described in claim 8, the automatic operation of the tea plantation management device can be made extremely accurate.

1 is a perspective view showing a tea ridge-spanning tea field management device of the present invention and a circuit diagram showing a hydraulic circuit. 1A is an enlarged perspective view of the tea ridge sensor and its surroundings, and FIG. 1B is a plan view and a front view of the counterweight. 1 is a circuit diagram showing a driving control device of the present invention; FIG. 4 is a circuit diagram showing another embodiment of the driving control device. FIG. 4 is a circuit diagram showing another embodiment of the driving control device. FIG. 1 is a circuit diagram showing a conventional driving control device.

The best mode for the travel control device in the field management device of the present invention and the field management device equipped with the same is as shown in the following examples, but these examples can be modified as appropriate within the scope of the technical concept of the present invention.

The following describes the "travel control device in a field management device and a field management device equipped with the same" of the present invention based on the illustrated embodiment. In this embodiment, the field management device is described using a riding type tea ridge straddling tea field management device 1 that is operated by an operator, but other devices such as a wireless controlled device without an operator on board, or a device equipped with a management machine unit such as a fertilizer spreader, pest control machine, or cultivator can also be used.

As shown in Figure 1 as an example, the tea ridge-spanning type tea plantation management device 1 comprises as its main components a traveling machine unit 2 that travels across the tea ridges T, a tea harvester unit 3 which is an example of a management machine unit, a storage section 4 that is provided behind the tea harvester unit 3 and stores the picked tea leaves, an relay transport device 5 that transports the tea leaves from the tea harvester unit 3 to the storage section 4, a tea ridge sensor 6 for detecting the degree of curvature of the tea ridges T, a travel control device 7, and a control device C.
The tea furrow-spanning tea garden management device 1 is designed to selectively perform pruning or picking work by appropriately replacing the tea harvester unit 3. When pruning work is performed, a pruning machine unit is attached as the tea harvester unit 3, while when picking work is performed, a picking machine unit is attached as the tea harvester unit 3.

Thus, in this specification, the tea harvester unit 3 is a collective term for the pruner unit that prunes the branches and trunks to shape the tree and restore its vigor, and the plucking unit that plucks the tea leaves. In addition, in this specification, when it is necessary to distinguish between left and right members, they are distinguished by adding L and R to the reference symbols, respectively, and the left and right here mean the left and right from the perspective of the person riding on the tea furrow-spanning tea plantation management device 1.
Below, each component that makes up the tea ridge-spanning tea plantation management device 1 will be described in detail.

First, the traveling machine unit 2 will be described. This unit is configured such that a traveling device 21, which uses crawlers as an example, is provided at the lower part of a frame 20 which is roughly gate-shaped when viewed from the traveling direction side, and is capable of traveling across tea ridges T.
The frame 20 is composed of left and right leg frames 20A positioned so as to rise above the spaces between the furrows, an upper frame 20B that horizontally connects the upper ends of the leg frames 20A, and a lifting frame 20C that is attached to the leg frames 20A so as to be freely raised and lowered.
The running device 21 is provided below the leg frame 20A.

Further, on the upper part of the upper frame 20B, there are provided an operator's seat 23 where an operator sits, an operation handle 23A, a parking switch, etc. The parking switch 25 is an operation switch for applying the brakes while traveling, stopping the traveling device 21 while traveling, and maintaining the stopped state.
A prime mover 22 using, for example, a diesel engine is mounted beside the driver's seat 23. As an example, the prime mover 22 drives a variable displacement hydraulic pump 71, which is a pump for HST, and the traveling device 21 is driven by hydraulic oil supplied from the variable displacement hydraulic pump 71. A hydraulic pump attached to the variable displacement hydraulic pump 71 drives the cutting blade 30 in the tea harvester unit 3, and also drives a cylinder (not shown) for lifting and shifting the lifting frame 20C. The hydraulic circuit that drives the traveling device 21 will be described in detail later.

Furthermore, a fan 26 for blowing the tea leaves cut by the tea harvester unit 3 is provided on the upper frame 20B, and is, for example, driven by the rotation of the prime mover 22. A ventilation duct 27 is connected to the fan 26, and compressed air is supplied to the tea harvester unit 3 through the ventilation duct 27.
As an example, the steering handle 23A can be tilted forward and backward to move forward and backward, and rotated left and right to turn left and right. Furthermore, a neutral detection sensor 28 is provided to detect the neutral state in which the steering handle 23A is not turned.

Next, the tea harvester unit 3 will be described. This is used to pluck tea leaves and trim branches and trunks, and as described above, a pruner unit or a plucking unit equipped with a rotary cutter type or clipper type cutting blade 30 is applied depending on the specifications.
The tea harvester unit 3 is detachably attached to the lifting frame 20C and is movable up and down, so that the actual harvesting height can be adjusted.
The lifting frame 20C, to which the tea harvester unit 3 is detachably attached, is provided with rollers that roll along the leg frame 20A, and the tea harvester unit 3, storage section 4 and relay transport device 5 are all suspended by a chain or the like and move up and down.

Next, the storage section 4 will be described. This is the section that stores the tea leaves harvested during the plucking operation, and in this embodiment, the main component is a container 41 that is open at the top.

Next, the relay transport device 5 will be described. This device transports the harvested tea leaves upward from the rear of the tea harvester unit 3 to the top of the storage section 4, and as shown in Figure 1, its main component is a relay duct 51 that rises from the tea harvester unit 3 to the top of the storage section 4.
The transport air from the fan 26 is blown into this relay duct 51 , transporting the tea leaves etc. upward to the storage section 4 .

Next, the tea rib sensor 6 will be explained. This is a device for detecting the positions of both sides of the tea rib T and detecting the degree of curvature of the tea rib T, and is equipped with a sensor unit 61 that uses a so-called potentiometer or the like that outputs an electrical signal in response to the movement of a detection plate 60 that comes into contact with the side of the tea rib T.
Specifically, as shown in Figures 1 and 2, left and right tea ridge sensors 6L, 6R are provided on the left and right leg frames 20A, respectively, and two support rods 63 are fixed to a rotating shaft 62 that is arranged approximately vertically, and the detection plate 60 is further provided on the support rods 63.
The detection plate 60 is, for example, a metal plate formed into a semi-cylindrical shape, with a reinforcing material appropriately provided on the inside of the semi-cylindrical portion.
A rotational force in a fixed direction is applied to the rotating shaft 62 by the action of a spring (not shown), so that the detection plate 60 is always rotated inward (towards the tea ridges T).
The rotation of the detection plate 60 is restricted by a regulating rod 64 on the pivot shaft 62 engaging with a hook 65 on the leg frame 20A, so that the detection plate 60 does not move inward more than necessary.

In this way, the detection plate 60 is attached to the bottom of the traveling unit 2 so that it can rotate freely in a horizontal plane, and rotates according to the degree of contact with the side of the tea ridge T. Therefore, the rotation angle of the left and right detection plates 60L, 60R differs depending on the curvature of the tea ridge T, and the sensor units 61L, 61R output this rotation angle difference as a fluctuation value, which is used to detect the curvature of the tea ridge T.

The tea ridge sensor 6 configured as described above is provided with a counterweight 66, which is a member for countering the rotational force generated in the pivot shaft 62 due to the gravity acting on the detection plate 60 when harvesting tea ridges T arranged along the incline of a slope.
Specifically, as shown in Figures 1 and 2, a weight support rod 66A is connected to a portion of the rotating shaft 62 forward of the support rod 63, and a weight piece 66B, for example, is detachably provided at the tip of this weight support rod 66A.
The weight of the weight piece 66B is appropriately selected according to the inclination angle of the inclined surface.

Next, the travel control device 7 for driving the traveling devices 21 will be described in detail. As shown in FIG. 1, the travel control device 7 is equipped with an HST (Hydro-Static Transmission) 7R that drives the right-side traveling device 21R, and an HST 7L that drives the left-side traveling device 21L, which are formed independently of each other.
Specifically, the travel control device 7 is configured by connecting, via a pipeline, a variable displacement hydraulic pump 71, which is an HST pump rotated and driven by the prime mover 22, to travel motors 72L, 72R that are driven by hydraulic oil supplied from the variable displacement hydraulic pump 71, to form HSTs 7L, 7R. In the hydraulic circuits that make up these HSTs 7L, 7R, bypass circuits 73L, 73R that short-circuit part or all of the hydraulic oil from the variable displacement hydraulic pump 71 without allowing it to act on the travel motors 72L, 72R are provided in parallel with the travel motors 72L, 72R.

The bypass circuits 73L, 73R are equipped with pressure-compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L, 75R, which are flow control mechanisms. The pressure-compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L, 75R are composed of electromagnetic proportional valves 751L, 751R, which correspond to the flow control unit, and pressure compensation valves 752L, 752R, which correspond to the pressure compensation function unit.
In addition, in Figures 1 and 3, when hydraulic oil flows in a counterclockwise direction in HST7L and in a clockwise direction in HST7R, the travel motors 72L, 72R rotate in a direction that moves the traveling devices 21L, 21R forward, while on the other hand, when hydraulic oil flows in a clockwise direction in HST7L and in a counterclockwise direction in HST7R, the travel motors 72L, 72R rotate in a direction that moves the traveling devices 21L, 21R backward.

The functions of the pressure compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L, 75R are as follows.
In the following, as shown in Figure 3, the pressure of the hydraulic oil between the variable displacement hydraulic pump 71 and the oil inlet side of the travel motors 72L, 72R is defined as P0, the pressure of the hydraulic oil between the oil outlet side of the travel motors 72L, 72R and the variable displacement hydraulic pump 71 is defined as P1, and the pressure of the hydraulic oil between the electromagnetic proportional valves 751L, 751R and the pressure compensation valves 752L, 752R is defined as P2.
The pressure compensating valves 752L, 752R, which correspond to the pressure compensating function portion, guide the hydraulic pressure P2 between the pressure compensating valves 752L, 752R and the electromagnetic proportional valves 751L, 751R, and guide the hydraulic pressure P0 to the opposite side of the electromagnetic proportional valves 751L, 751R. Then, the flow rate pipes from the electromagnetic proportional valves 751L, 751R are operated so that the differential pressure (P0-P2) between the inlets and outlets of the electromagnetic proportional valves 751L, 751R is kept constant, thereby compensating the flow rate between the bypasses to be constant.

In this embodiment, check valves 76L, 76R are provided downstream of the pressure-compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L, 75R when the travel motors 72L, 72R are rotated in the forward direction. By providing such check valves 76L, 76R, it is possible to prevent hydraulic oil from flowing back toward the pressure-compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L, 75R when moving in reverse, and thus to prevent reverse travel being impeded.

Parking brake bypass circuits 78L, 78R are provided in parallel with the bypass circuits 73L, 73R, and are provided with parking brake control valves 771L, 771R. These parking brake control valves 771L, 771R are activated when the driver operates the parking switch 25, and fully open the electromagnetic valves that constitute the parking brake control valves 771L, 771R to stop the supply of hydraulic oil to the travel motors 72L, 72R.

As described above, consider the case where the tea ridge-straddling tea garden management device 1 traveling on a flat surface is set to an opening degree of 80% for the electromagnetic proportional valve 751L, which is part of the pressure compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L, 75R, and the opening degree of the electromagnetic proportional valve 751R is set to 0%, and the tea ridge-straddling tea garden management device 1 traveling on a flat surface is set to an opening degree of 80% for the electromagnetic proportional valve 751R, and the tea ridge-straddling tea garden management device 1 traveling on a flat surface is set to an opening degree of 0% for the electromagnetic proportional valve 751L, and the tea ridge-straddling tea garden management device 1 traveling on a flat surface is set to an opening degree of 80% for the electromagnetic proportional valve 751R, and the tea ridge-straddling tea garden management device 1 traveling on a flat surface is set to an opening degree of 0% for the electromagnetic proportional valve 751R.
When the tea ridge-spanning tea plantation management device 1 travels up a slope, the load on the travel motors 72L, 72R increases, causing the pressure P0 of the hydraulic oil between the variable displacement hydraulic pump 71 and the oil inlet side of the travel motors 72L, 72R to rise, increasing the pressure difference (P0-P1), and tending to increase the flow rate of hydraulic oil flowing into the bypass circuit 73L.
However, in the present invention, due to the function of the aforementioned pressure compensated electromagnetic proportional flow control valve (electromagnetic proportional flow priority valve) 75L, when the pressure P0 increases, the pressure compensating valve 752L reduces the flow line from the electromagnetic proportional valve 751L, thereby increasing pressure P2 by the amount of the increase in pressure P0.
Therefore, the value of the pressure difference P0-P2 before and after the electromagnetic proportional valve 751L does not change, and the amount of hydraulic oil flowing through the electromagnetic proportional valve 751L, i.e., the bypass circuit 73L, is maintained at a predetermined value.
As described in the Background Art, the amount of hydraulic oil is determined by a control signal (current value) sent by the control device C to the electromagnetic proportional valves 751L, 751R based on the speed of the traveling devices 21L, 21R calculated from input values of the tea ridge sensors 6R, 6L, the parking switch 25, the tilt sensor 24, and the neutral detection sensor 28, etc.
As a result, the amount of hydraulic oil supplied to the travel motor 72L is kept at a predetermined value, and the rotation speed is kept constant, so that the speed of the travel device 21L is kept at a desired value.

On the other hand, when the tea ridge-straddling tea plantation management device 1 travels down a slope, the load on the travel motors 72L, 72R decreases, so that the pressure P0 of the hydraulic oil between the variable displacement hydraulic pump 71 and the oil inlet side of the travel motors 72L, 72R decreases, the pressure difference (P0-P1) decreases, and the flow rate of hydraulic oil flowing into the bypass circuit 73L tends to decrease.
However, in the present invention, when the pressure P0 drops, the function of the aforementioned pressure compensated electromagnetic proportional flow control valve (electromagnetic proportional flow priority valve) 75L operates to enlarge the flow line from the electromagnetic proportional valve 751L via the pressure compensating valve 752L, thereby reducing the pressure P2 by the amount of the pressure drop in pressure P0.
Therefore, the value of the pressure difference P0-P2 before and after the electromagnetic proportional valve 751L does not change, and the amount of hydraulic oil flowing through the electromagnetic proportional valve 751L, i.e., the bypass circuit 73L, is maintained at a predetermined value.
As a result, the amount of hydraulic oil supplied to the travel motor 72L is kept at a predetermined value, and the rotation speed is kept constant, so that the speed of the travel device 21L is kept at a desired value.

In addition, in the HST7R, the opening degree of the electromagnetic proportional valve 751R is 0% and no hydraulic oil flows through the bypass circuit 73R, so even if the tea ridge-spanning tea farm management device 1 travels up or down a slope, the rotation speed of the travel motor 72R does not change.

In addition, regarding the left-right tilt of the tea field management device, the degree of tilt is detected by the aforementioned tilt sensor 24, and the opening degree of the electromagnetic proportional valves 751L and 751R is corrected according to the degree of tilt.

Other Examples
The present invention is based on the above-described embodiment, but within the scope of the technical concept of the present invention, for example, the following embodiments can be adopted.
First, in the above-mentioned basic embodiment, the pressure compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L and 75R are shown as examples of pressure compensated flow control valves, but it is also possible to keep the flow rate flowing through the bypass circuits 73L and 73R constant regardless of the running load by using a known so-called pressure compensated flow control valve that has a pressure compensating valve portion and adjusts the flow path throttle portion. In this case, however, although the amount of hydraulic oil flowing through the bypass portion cannot be adjusted by flow control using a control signal, automatic steering is possible by arranging a solenoid valve in series downstream of the pressure compensated flow control valve and opening and closing only one of the solenoid valves arranged in HST7L and HST7R to reduce the rotation speed of the traveling motor.

In addition, instead of the solenoid valves (parking brake control valves 771L, 771R) provided in parallel with the bypass circuits 73L, 73R shown in Fig. 3, the pressure-compensated solenoid proportional flow control valves (solenoid proportional flow priority valves) 77L, 77R may be arranged in the opposite direction to the pressure-compensated solenoid proportional flow control valves (solenoid proportional flow priority valves) 75L, 75R as shown in Fig. 4. In this case, when the driver operates the parking switch 25, the solenoid proportional valves 751L, 751R are fully opened simultaneously during forward travel to stop the supply of hydraulic oil to the travel motors 72L, 72R, and the solenoid proportional valves 771L, 771R are fully opened simultaneously during reverse travel to stop the supply of hydraulic oil to the travel motors 72L, 72R. This configuration not only serves as a substitute for the solenoid valves (parking brake control valves 771L, 771R), but also provides the same functionality as the pressure-compensated solenoid proportional flow control valves (solenoid proportional flow priority valves) 75L, 75R that function when traveling forward, making it possible to avoid fluctuations in hydraulic oil caused by motor load fluctuations when traveling in reverse.

As shown in Figure 5, it is also possible to provide the function of the parking brake control valves 771L, 771R to the electromagnetic proportional valves 751L, 751R, which correspond to the flow rate adjustment parts in the pressure-compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L, 75R, thereby eliminating the parking brake control valves 771L, 771R. In this case, the parking brake function is handled by the parking brake control, which is a known technology (see JP 2005-021127 [0033]), but there is an effect of saving space for the control valves, etc.

Also, as shown in FIG. 5, in order to construct the driving control device 7 at low cost, the pressure-compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L, 75R as the flow control mechanism and the check valves 76L, 76R arranged downstream thereof can be integrated into the same casing or the like. In that case, since the electromagnetic proportional valves 751L, 751R only support the parking brake when moving forward, a separate mechanical brake or the like can be provided to support the parking brake on both the forward and reverse sides.

Furthermore, in order to construct the driving control device 7 at low cost, in addition to the pressure-compensated electromagnetic proportional flow control valves (electromagnetic proportional flow priority valves) 75L, R and the check valves 76L, R, the parking brake control valves 771L, 771R can be integrated into the same casing, etc.

REFERENCE SIGNS LIST 1 Tea ridge spanning type tea garden management device 2 Traveling machine unit 20 Frame 20A Leg frame 20B Upper frame 20C Lifting frame 21 Traveling device 21L Traveling device 21R Traveling device 22 Prime mover 23 Control seat 23A Control handle 24 Tilt sensor 25 Parking switch 26 Fan 27 Air duct 28 Neutral detection sensor 3 Tea harvester unit 30 Cutting blade 4 Storage section 41 Container 5 Intermediate transport device 51 Intermediate duct 6 Tea ridge sensor 6L Tea ridge sensor 6R Tea ridge sensor 60 Detection plate 60L Detection plate 60R Detection plate 61 Sensor unit 61L Sensor unit 61R Sensor unit 62 Rotating shaft 63 Support rod 64 Regulating rod 65 Hook 66 Counterweight 66A Weight support rod 66B Weight piece 7 Travel control device (hydraulic circuit)
7L HST
7R HST
71 Variable displacement hydraulic pump 72L Travel motor 72R Travel motor 73L Bypass circuit 73R Bypass circuit

75L Pressure compensated electromagnetic proportional flow control valve (electromagnetic proportional flow priority valve)
75R Pressure compensated electromagnetic proportional flow control valve (electromagnetic proportional flow priority valve)

751L Proportional solenoid valve 751R Proportional solenoid valve 752L Pressure compensation valve 752R Pressure compensation valve

76L Check valve 76R Check valve

77L Pressure compensated electromagnetic proportional flow control valve (electromagnetic proportional flow priority valve)
77R Pressure compensated electromagnetic proportional flow control valve (electromagnetic proportional flow priority valve)
771L Control valve for parking brake 771R Control valve for parking brake 772L Pressure compensation valve 772R Pressure compensation valve 78L Bypass circuit for parking brake 78R Bypass circuit for parking brake 79L Check valve 79R Check valve

T Tea ridge C Control device

Claims (8)

A travel control device for a farm management device that has a cultivator unit attached to a travel device that uses a pair of left and right crawlers as a travel body, and travels across ridges to perform the desired farm management,
Each of the traveling devices is driven by hydraulic oil supplied from the HST pump, and the traveling motors that drive the traveling devices are supplied with hydraulic oil through separate left and right hydraulic circuits,
Each hydraulic circuit is provided with a bypass circuit that short-circuits a portion of the hydraulic oil from the HST pump without allowing it to act on the travel motor.
A travel control device for a farm management device, comprising a flow rate adjustment mechanism for maintaining a constant flow rate through a bypass circuit regardless of the travel load.
2. A travel control device for a farm management device according to claim 1, wherein the flow rate adjustment mechanism is a pressure compensated electromagnetic proportional flow rate adjustment valve.
3. A travel control device for a farm management device according to claim 2, wherein the flow rate of hydraulic oil passing through the bypass circuit can be controlled only by a control signal from a control device which detects a sensor signal.
4. A travel control device for a farm management apparatus according to claim 1, 2 or 3, wherein a check valve is provided downstream of a flow path of the flow rate adjustment mechanism provided in the bypass circuit.
5. A travel control device for a farm management device according to claim 4, wherein the flow rate adjustment mechanism and the check valve are integrated together.
6. A travel control device in a farm management device according to claim 1, 2, 3, 4 or 5, characterized in that a parking brake bypass circuit equipped with a valve for short-circuiting hydraulic oil from the HST pump without applying it to the travel motor is provided in parallel with the bypass circuit equipped with the flow rate adjustment mechanism.
6. A travel control device for a farm management device according to claim 5, wherein the flow rate adjustment mechanism is integrated with the check valve and a parking brake control valve provided in the parking brake bypass circuit.
A farm management device comprising a driving control device according to any one of claims 1, 2, 3, 4, 5, 6 and 7.

Images