JPH09172825A - Steering apparatus in farm working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the possession of excellent steering characteristic fitting to turning when a farm working machine makes turn and, at the same time, the possession of excellent steering characteristic fitting to straight working traveling when it makes straight working traveling. SOLUTION: A farm working machine is provided with a liftable working apparatus and a power steering unit 24 driven by a pressed oil from a hydraulic pump 22. The machine is also provided with a rise-detecting means for detecting the rise of the working apparatus. In a pressed oil feeding passage from the hydraulic pump 22 to a power steering unit 24 is placed a flow dividing valve 25 for controlling the feed of the pressed oil to the power steering unit 24 at a constant level. An electric valve 26 reciprocally changing over from the first state where the pressed oil is fed to the power steering unit 24 through the flow dividing valve 25 according to the detection of the rise by the rise-detecting means and the second state where the pressed oil is fed to the power steering unit without passing the flow dividing valve 25 is also placed in the pressed oil passage. A surplus oil passage 27 of the flow dividing valve 25 is connected near a tank port T of the power steering unit 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device for an agricultural work machine such as a wetland work machine typified by a rice transplanter. The present invention relates to a steering device for an agricultural work machine provided with a steering unit.

[0002]

2. Description of the Related Art In a conventional steering device for an agricultural machine of this type, a diversion valve for controlling the pressure oil supply to the power steering unit at a constant flow rate is provided in a pressure oil supply passage from a hydraulic pump to the power steering unit. , Regardless of fluctuations in the amount of pressure oil supplied by the hydraulic pump due to fluctuations in the engine load that drives the hydraulic pump, etc., a constant flow of pressure oil is supplied to the power steering unit to prevent the steering characteristics from changing. It was

[0003]

Considering the traveling condition of an agricultural work machine in a field, when traveling in the field, a working device such as a planting device is raised to turn at the end (headland) of the field. And, there is a straight running work typified by the planting run of rice transplanters, and in turning, it is required that the handle be as light as possible in order to quickly turn the handle large and make the turn with a small radius. In straight running work, a heavy steering wheel is required to improve straight running stability.

However, in the conventional steering device, since the constant-flow pressure oil supply amount to the power steering unit is constant and the steering characteristic is constant, the steering characteristic sacrifices either turning or straight running work. Or, the steering characteristics had a difficulty in both turning and straight running work.

That is, the amount of pressure oil supplied to the power steering unit is increased in accordance with the demand at the time of turning to increase the assisting force for steering by the power steering unit, so that a small steering wheel operating force required for steering can be obtained. If it is made smaller, the steering wheel can be swiftly turned to make a small turning, while the steering wheel is too light during straight running work, which makes straight running very difficult. On the other hand, the steering force required for steering is increased by reducing the amount of pressure oil supplied to the power steering unit and weakening the assisting force for steering by the power steering unit according to the demand for straight running work. By doing so, a straight steering operation can be performed with good straight running stability by not steering with a small steering wheel operating force, but on the other hand, the steering wheel is too heavy when turning and a very large steering wheel operating force is required for turning. Is greatly reduced.

However, if the amount of pressure oil supplied to the power steering unit is set to a halfway value, it is not possible to improve the stability of the straight running work and the turning performance.

An object of the present invention is to make it possible to obtain a good steering characteristic for the turning at the time of turning, and at the same time, obtain a good steering characteristic for the straight running at the time of running straight. .

[0008]

The constitution, operation and effect of the present invention according to claim 1 are as follows.

[Structure] In an agricultural work machine provided with a work device that can be raised and lowered and a power steering unit that is operated by pressure oil from a hydraulic pump, a lift detection for detecting a lift operation of the work device or a lift of the work device. Means is provided in the pressure oil supply path from the hydraulic pump to the power steering unit to control the amount of pressure oil supplied to the power steering unit to a constant flow rate, and the diversion based on the rise detection by the rise detection means. An electric valve that reversibly switches from a first state in which pressure oil is supplied to the power steering unit via the valve to a second state in which pressure oil is supplied to the power steering unit without passing through the diversion valve, and the surplus of the diversion valve is provided. The oil passage is connected near the tank port of the power steering unit.

[Operation] The working device such as the planting device is held at the lowering work position when the vehicle is running straight ahead, and the working device is operated to the ascending position when turning at the end of the field. Therefore, the raising / lowering operation for the working device or the raising / lowering motion of the working device itself can be used as a determination item for distinguishing between the turning and the straight work traveling.

Focusing on the above points, in the case of a rise, the first state in which a constant flow rate of pressure oil is supplied to the motor-operated valve by detecting it by the rise detection means and the power steering unit via the flow dividing valve. The pressure oil is supplied to the power steering unit without passing through the shunt valve, and the working oil is supplied to the power steering unit while the working device is being raised. Since the constant flow rate is supplied to the power steering unit during straight running work, the assist force of the power steering unit during turning is greater than the assist force of the power steering unit during straight running. Can be large.

Moreover, when the work device is lowered and the vehicle is traveling straight ahead, that is, when pressure oil is being supplied to the power steering unit via the flow dividing valve, the excess oil of the flow dividing valve is passed through the excess oil flow path. By supplying back pressure to the power steering unit near the tank port and applying back pressure to the power steering unit, resistance is added to the operation of the power steering unit. It is possible to reduce the assist force of the power steering unit during the straight traveling work traveling, and increase the difference between the assist force during the straight traveling work traveling and the assist force during the turning.

[Effects] As a result, according to the present invention, when the vehicle is traveling straight ahead, the assisting force of the power steering unit can be reduced to bring out steering characteristics with excellent straight traveling stability, while at the time of turning, the power steering unit assists. By increasing the force, the steering characteristics with excellent turning performance can be revealed, and the steering characteristics can be automatically switched.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An application example to a riding rice transplanter, which is an example of an agricultural working machine, will be described. The riding rice transplanter, as shown in FIG.
A seedling planting device 3, which is an example of a working device, is movably connected to a rear portion of a self-propelled vehicle body 2 equipped with an engine 1 via a link 4, and acts on the link 4 to operate the seedling planting device 3
A hydraulic cylinder 5 for moving up and down is provided.

The self-propelled vehicle body 2 is provided with a pair of left and right steering driving front wheels 6, a pair of left and right driving rear wheels 7, and a driving section 8.

The driver 8 is provided with a driver's seat 9, a steering handle 10, a lifting / working lever 11, and a forced operating lever 12.

The seedling planting device 3 operates in conjunction with movement of the seedling stand 14 which is reciprocally driven and moved in the left-right direction at a set stroke on the device frame 13 connected to the link 4. Seedling stand 14
A mating plant 15 is attached for taking out and planting the above mat seedlings in increments of a unit, and a leveling float 16 that swings up and down around a rear fulcrum R with the height fluctuation of the device frame 13 with respect to the mud is attached. ing.

As shown in FIG. 2, the leveling float 16 is in a set rocking posture with respect to the device frame 13 when the device frame 13 is located at the set ground level, and the device frame 13 is set at a level higher than the set ground level. Also oscillates in the front lower direction as it is positioned higher, and oscillates in the front upper direction as the device frame 13 is positioned lower than the set ground height. Therefore, when the seedling planting device 3 rises, the leveling float 16 swings in the front downward direction. Reference numeral 17 detects the amount of rocking of the leveling float 16 from the set rocking posture with respect to the apparatus frame 13.
That is, it is a potentiometer-type height sensor that detects the height of the device frame 13 above ground.

The elevating / working lever 11 moves the seedling planting device 3 up and down, and at the same time, the seedling planting device 3 is operated.
A lever for opening and closing the planting clutch 18 that opens and closes the transmission of power to and is arranged on the lateral side of the driver's seat 9, and is formed on the operation guide plate 19 as shown in FIG. The operation guide hole 20 guides the operation movement to each operation position.

As shown in FIG. 4, the forced operating lever 12 is attached to the steering column so as to be vertically swingable, and is biased to swing to a neutral position in the middle of the vertical swing range.

As shown in FIG. 3, the operating positions of the elevating / lowering lever 11 include an ascending position U, a descending position D, a clutch disengaged position OFF, a clutch engaged position ON and an automatic position AU. The raised position U is the planting clutch 18
This is a position where the seedling planting device 3 is lifted in the state of cutting. The lowered position D is a position where the seedling planting device 3 is lowered. The clutch disengagement position OFF is a position where the planting clutch 18 is disengaged while the seedling planting device 3 is lowered, that is, the operation of the seedling planting device 3 is stopped. When the clutch engagement position is ON, the planting clutch 18 is engaged while the seedling planting device 3 is lowered.
That is, it is a position where the seedling planting device 3 is operated.

The riding rice transplanter, as shown in FIG. 2, controls the hydraulic cylinder 5 and the planting clutch 18 based on the operation of the lifting / working lever 11 and the detection result of the height sensor 17. 21.

The control device 21 operates [1] the hydraulic cylinder 5 so as to raise the seedling planting device 3 based on the operation movement of the raising / lowering / working lever 11 to the raised position U, and [2] the raising / lowering / raising / lowering operation. Based on the operation movement of the work lever 11 to the lowered position D, the hydraulic cylinder 5 is operated so as to lower the seedling planting device 3, and [3] the seedling planting device 3
When the ground leveling float 16 comes into contact with the ground and the height detected by the height sensor 17 becomes less than a set value, the device frame 13 is set to the set ground height based on the detection result of the height sensor 17. The hydraulic cylinder 5 is operated so that the (seedling planting device 3) is positioned, and [4] lifting / lowering / operating of the working lever 11 to disengage the clutch disengagement position causes the planting clutch 18 to be disengaged, [5] lifting・ The planting clutch 18 is engaged and activated based on the operation movement of the work lever 11 to the clutch engagement position ON, and [6] lifting / lowering is performed.
When the work lever 11 is at the automatic position AU and the forced operation lever 12 is operated once upward, the hydraulic cylinder 5 is operated so as to raise the seedling planting device 3,
When the forced operation lever 12 is operated once downward, the hydraulic cylinder 5 is operated so as to lower the seedling planting device 3, and when the forced operation lever 12 is subsequently operated downward again, the planting clutch 18 is engaged. It operates.

That is, the elevating / working lever 11 has the lowered position D, the clutch disengaged position OFF, and the clutch engaged position O.
When it is N, the seedling planting device 3 is moved up and down based on the detection result of the height sensor 17 to automatically control the planting depth.

As shown in FIG. 2, the steering apparatus is operated by the pressure oil from the hydraulic pump 22 driven by the engine 1 to operate the steering handle 10.
The pitman arm 2 of the steering front wheel 6 based on the operation of
3, an integral type power steering unit 24 for operating 3, an ascending detection means, a shunt valve 25, and an electric valve 2
6.

The rising detecting means is means for detecting a rising operation on the seedling planting device 3 or a rising of the seedling planting device 3, and in this embodiment, the seedling planting device 3 is carried out.
The height sensor 17
It is composed of That is, the height sensor 17 is configured to output a rising signal when the height sensor 17 detects that the leveling float 16 has swung downward from the set swing posture by the set angle θ.

The flow dividing valve 25 (flow priority valve) is provided in a pressure oil supply passage from the hydraulic pump 22 to the power steering unit 24 and controls the pressure oil supply amount to the power steering unit 24 at a constant flow rate. The surplus oil flow passage 27 of the flow dividing valve 25 is connected to the vicinity of the tank port T of the power steering unit 24 via a surplus oil oil passage 28. Of course, the constant flow passage 29 is connected to the pump port P of the power steering unit 24 via the oil passage 30.

The motor-operated valve 26 is an electromagnetic valve, and is in a first state in which the pressure oil from the hydraulic pump 22 is supplied to the power steering unit 24 via the flow dividing valve 25, and the power steering unit 24 without passing through the flow dividing valve 25. More specifically, it is a valve that can be switched to a second state in which it is supplied to the power steering unit 24 via the bypass passage 31 for the flow dividing valve 25, and is actuated in the first state and energized by energization. It switches to the second state in opposition.
At the portion of the oil passage 30 on the upstream side of the connection portion with the bypass passage 31, a check valve for preventing backflow of the pressure oil to the flow dividing valve 25 in a mode in which the solenoid valve 26 is switched to the second state. A valve 32 is provided.

Steering characteristic control means 33 is provided for reversibly switching the solenoid valve 26 from the first state to the second state when a rising signal is output from the height sensor 17. In the figure, the control device 2
However, the steering characteristic control means 33 may be provided separately from the control device 21.

Therefore, in the above-described embodiment, the electromagnetic steering valve 26 is switched to the first state during the work traveling with the seedling planting device 3 being lowered (generally, the straight traveling work traveling). Is supplied with a constant amount of pressure oil, and excess oil is returned to the vicinity of the tank port T to act as a back pressure of the power steering unit 24. As a result, a constant amount of pressure oil is supplied. Steering is performed based on the operation of the steering wheel 10 with a smaller assist force. On the other hand, when the seedling planting device 3 is raised and turning at the end of the field, the solenoid valve 26 is switched to the second state, so that the power steering unit 24 receives the entire amount of pressure oil supplied from the hydraulic pump 22. As a result, steering based on the operation of the steering handle 10 is performed with a larger assist force than the above.

That is, there is a large difference in assisting force between when traveling straight ahead and when turning, and when traveling straight ahead, the steering wheel 10 is heavy due to the small assisting force, and the straightness is stable. At the time of turning, since the assisting force is large, the steering handle 10 becomes light and the turning operability is improved. In other words, the steering characteristic that can improve the straight traveling stability can be obtained when the vehicle is traveling straight ahead, and the steering characteristic that can improve the turning operability can be obtained when the vehicle turns.

[Other Embodiments] In the above embodiment, the steering characteristics are automatically and reversibly changed by raising the seedling planting device 3 from the characteristics of straight running operation to the characteristics suitable for turning. However, as shown by the chain double-dashed line in FIG. 3, an elevation detection sensor S1 for detecting the operation of the elevation / work lever 11 to the elevation position U is provided, and based on the elevation detection of the elevation detection sensor S1, The motor-operated valve 26 shown as a solenoid valve may be configured and implemented to automatically and reversibly switch from the first state to the second state. Further, as indicated by the chain double-dashed line in FIG.
A raising operation motion detection sensor S2 for detecting the raising operation motion is provided, and based on the rising operation motion detection of the raising operation motion detection sensor S2, the motor-operated valve 26 represented by a solenoid valve is automatically changed from the first state to the second state. You may implement | achieve and implement so that it may switch reversibly. Further, the rise detection sensor S1
And the ascending operation motion detection sensor S2 are provided, and if either one of them is detected, the motor-operated valve 26 shown by a solenoid valve is automatically and reversibly changed from the first state to the second state based on the detection. It may be configured so as to be switched selectively.

Although an electromagnetic valve is provided as the electric valve 26 in the above embodiment, the electric valve 26 may be a valve that operates using an electric motor as an actuator.

In the above embodiment, an example of application to a riding rice transplanter is shown, but the present invention can be applied to various agricultural working machines such as wetland working machines.

Incidentally, reference numerals are written in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of the drawings]

FIG. 1 is a side view of a riding rice transplanter showing an embodiment.

FIG. 2 is a control system diagram showing an embodiment.

FIG. 3 is a plan view of an operation guide plate showing an embodiment.

FIG. 4 is a side view of a main part showing an embodiment.

[Explanation of symbols]

 3 Working device 22 Hydraulic pump 24 Power steering unit 25 Dividing valve 26 Electric valve 27 Excess oil flow path T Tank port

Claims (1)

[Claims] 1. An agricultural work machine provided with a work device (3) which can be moved up and down and a power steering unit (24) which is operated by pressure oil from a hydraulic pump (22), and is raised with respect to the work device (3). Ascending detection means for detecting an increase in the operation or working device (3) is provided, and the hydraulic pump (22) drives the power steering unit (2).
A flow dividing valve (2) for controlling the amount of pressure oil supplied to the power steering unit (24) to a constant flow rate on the pressure oil supply path to (4).
5) and the flow dividing valve (25) from the first state in which pressure oil is supplied to the power steering unit (24) through the flow dividing valve (25) based on the rise detection by the rise detecting means.
Motorized valve (26) that reversibly switches to a second state in which pressure oil is supplied to the power steering unit (24) without passing through
And a surplus oil flow path (27) of the flow dividing valve (25) is connected near the tank port (T) of the power steering unit (24).