JPH03246166A - Work vehicle steering device - Google Patents

Abstract

PURPOSE:To turn a working vehicle quickly and smoothly without causing the bad condition of a clutch by intermittently switching a two-position selector valve in such a state that it is switched to a drainage condition during a preset time on detecting that a hydraulic cylinder reaches the stroke end. CONSTITUTION:When a clutch disconnect operation command for one clutch is given, a control means C switches a three-position selector valve 17 to the pressure oil supply condition in a designated direction and supplies pressure oil to designated hydraulic cylinders 13L, 13R. The start of supplying pressure oil causes the cylinders 13L, 13R to contract, whereby steering clutches 12L, 12R are disconnected. Just after that, the cylinders 13L, 13R reaches the stroke end, and when the reach is detected by a sensor 20, the control means C switches a two-position selector valve 19 to the drainage condition and maintains the drainage condition extending over a preset time. After the lapse of the preset time, the control means C switches the selector valve 19 to the drainage stop condition, and supplies pressure oil to the designated cylinders 13L, 13R again. The above switching operation of the selector valve 19 is repeated until a clutch disconnect command is cancelled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a transmission system for a pair of traveling devices, each of which is provided with a steering clutch that is biased to return to the entry side. a steering hydraulic cylinder that operates the hydraulic cylinder, and an electromagnetically operated three-position switchable state that can be freely switched between two states in which pressure oil is selectively supplied to the hydraulic cylinder and a neutral state in which pressure oil is discharged from these hydraulic cylinders. a switching valve;
An electromagnetically operated two-position switching valve that can be freely switched between a state in which pressure oil is discharged from each hydraulic cylinder and a state in which the discharge of oil is stopped, and a three-position switching valve that is commanded based on a clutch disengagement operation command. The present invention relates to a steering device for a working vehicle, which is provided with a control means for switching a state in which pressure oil is supplied to a hydraulic cylinder, and intermittently switching the two-position switching valve between an oil draining state and an oil draining stop state. .

[Conventional technology]

Some work vehicles, such as combine harvesters, are configured to change the direction of the vehicle body by intermittently disengaging one of the left and right steering clutches and slowing down the drive speed of the left and right traveling gear. .

Generally, as shown in Fig. 6, an electromagnetic three-position switching valve has a delay time from energization to switch to the pressure oil supply state until the pressure actually starts to rise, and
There is a long delay between energization to switch to the neutral state and the time when the pressure actually starts to drop.In contrast, two-position switching valves (for example, poppet valves) have a long delay when switching to the neutral state. The delay time from energization until pressure oil actually starts to be discharged is short, as well as the delay time from energization to switch to the oil drain stop state until discharge actually starts to stop. , 3-position switching valves have a long delay time, so they are not suitable for intermittent switching operations.
Since the two-position switching valve has a short delay time, it is suitable for intermittent switching operations.

For this reason, in the conventional steering device of a work vehicle, as disclosed in Japanese Patent Application Laid-open No. 62-163871, when receiving a command to disengage one of the clutches, the 3-position switching valve is instructed. After switching to the pressure oil supply state to the specified direction, the two-position switching valve is intermittently switched between the oil drain state and the oil drain stop state at predetermined time intervals. The clutch is being disengaged and operated intermittently.

[Problem to be solved by the invention]

In order to make the vehicle change direction quickly and smoothly, it is necessary to shorten the disengagement and engagement times of the steering clutch.
To achieve this, it is necessary to switch the two-position switching valve in a short period of time.Switching the two-position switching valve in a short period of time is relatively easy because it is sufficient to shorten the period of energization. However, there is a short lag time from when the two-position switching valve is switched to the oil drain stop state until the hydraulic cylinder reaches the stroke end on the clutch release side, and this lag time is due to the amount of pump discharge. There are variations due to fluctuations, etc. Therefore, even if the two-position switching valve is switched to the oil drain stop state, the switch to the oil drain state may occur without waiting for the hydraulic cylinder to reach the stroke end on the clutch release side.

In short, if the two-position switching valve is operated in a short period of time, the instructed steering clutch may not be fully disengaged, resulting in clutch failure, and vibrations may occur that prevent quick and smooth direction changes. be.

The present invention has been made in view of this situation, and its purpose is to enable quick and smooth direction changes without causing the latch failure as described above.

[Means to solve the problem]

The steering device for a work vehicle according to the present invention is provided with a sensor for detecting whether or not the hydraulic cylinder has reached the stroke end on the clutch release side, and the control means is configured to control the hydraulic cylinder to reach the stroke end by the sensor. The first feature is that when it is detected that this has occurred, the two-position switching valve is intermittently switched to the oil draining state for a set period of time.

A second feature of the sensor is that it is a pressure sensor that detects the oil pressure supplied to the hydraulic cylinder.

[For production]

According to the first feature, when receiving a command to disengage one of the clutches, the control means switches the three-position switching valve to a state in which pressure oil is supplied to the commanded direction, and controls the hydraulic pressure of the commanded direction. Supply pressure oil to the cylinder. When pressure oil supply is started, the hydraulic cylinder is contracted and the steering clutch is disengaged. Soon thereafter, the hydraulic cylinder reaches the end of its stroke, which is detected by the sensor, and the control means
The two-position switching valve is operated to switch to the oil draining state, and this oil draining state is maintained for a set time. When the set time has elapsed, the control means switches the two-position switching valve to the oil drain stop state, and supplies pressure oil again to the designated hydraulic cylinder. This switching operation of the two-position switching valve between the oil drain state and the oil drain stop state is repeated until the clutch disengagement operation command is released. Incidentally, the set time can be changed arbitrarily.

The second feature specifies the sensor in the first feature. Whether or not the hydraulic cylinder has reached its stroke end is detected by the oil pressure supplied to the hydraulic cylinder. In this case, the pressure detected by the sensor is set to be higher than the pressure when the steering clutch is reliably engaged and operated.

〔Effect of the invention〕

According to the first feature, when the operation clutch is reliably engaged and operated, the two-position switching valve is immediately switched to the oil draining state, so the disengagement time of the operation clutch can be extremely shortened, This allows for faster and smoother direction changes.

The second feature provides the most suitable sensor for implementing the invention. In short, if it is to be detected by mechanical operation whether or not a hydraulic cylinder has reached its stroke end, it must be detected for each hydraulic cylinder, and at least two sensors must be provided. However, if it is a pressure sensor, if it is between a hydraulic pump and a 3-position switching valve or a 2-position switching valve, 1
It is sufficient to provide only one.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

As shown in Figure 5, a combine harvester used as a working vehicle raises and harvests the planted stems of rice, wheat, etc. in the field, and while transporting the harvested stems, it changes its posture to a sideways position and then carries the feed chain. (1), a reaping section (2) that transfers the receiver to the feed chain (1), a threshing device (3) that threshes the stem culms that are conveyed by the feed chain (1), and sorts and collects the grains;
Pair of crawler-type traveling bags! Equipped with (4L) and (4R).

A mounting frame (6) for the weeding tool (5L) and (SR) provided on both left and right ends of the tip side of the reaping section (2),
(6) Each is equipped with a tracing sensor (Sl) and (S) for detecting the offset position of the body in the lateral direction with respect to the stem culm (H).As shown in Figs. 3 and 4, , these copying sensors (Sl), (SZ) are connected to the reaping section (2).
) and a sensor bar (7) that contacts the base of the stem culm (H) introduced into the body while being biased toward the front of the aircraft, and rotates toward the rear of the aircraft by an angle corresponding to the contact position. , and a potentiometer (R) that detects the rotation angle of the sensor bar (7), and is used to control the machine (V) to automatically travel along the 8 culms (H) during reaping work. Control parameters are detected and provided to the control device (C).

In addition, the stem culm (H) planted in the field is connected to the sensor bar (7).
), the output signal of the potentiometer (R) changes intermittently. The control device (C) is configured using a microcomputer, and after performing signal processing such as averaging the output signal of the potentiometer (R) and detecting the maximum value per unit time, The amount of deviation in the lateral direction is detected.

Each transmission system for the left and right crawler steering devices (4L) and (4R) is provided with a pair of left and right steering clutches (12L) and (12R) that are biased to return to the entry side, as well as a pair of steering clutches (12L) and (12R) for steering. Hydraulic cylinder (13L), (1
3R), the steering clutch (12L), (
The steering device is constructed in such a manner that the steering clutches (12L) and (12R) are connected to each other so that the steering clutches (12R) are operated to the disengaged state.

As shown in Fig. 2, a steering clutch (12L).

(12R) and a pair of hydraulic cylinders (13L), (1
3R) are linked by a swing arm (15) pivotally supported by each of the steering clutch shafts (14), and pressure oil is selectively supplied to the hydraulic cylinders (13L) and (13R). and those hydraulic cylinders (13L), (
An electromagnetically operated three-position switching valve (17) is provided, which can be freely switched to a neutral state in which pressure oil is discharged from the valve (13R), and is biased to return to the neutral state by a spring (16).

Also, the hydraulic cylinder (13L), (13J?)
The state of reducing the pressure oil supply pressure to Il! (An electromagnetically operated two-position switching valve (19) is provided which can freely switch between draining oil and one position and is biased by a spring (18) to return to the non-depressurizing state (oil draining stop state B). Position switching valve (19)
It uses a poppet valve that allows for high-speed response. Furthermore, a pressure sensor (20) is provided to detect the pressure of pressure oil supplied to the hydraulic cylinders (13L) and (13R).

When the three-position switching valve (17) is switched from the neutral state to the pressure supply state to one side, the swing arm (15) moves as the hydraulic cylinder (13L or 13R) to which pressure is supplied extends. The steering clutch (1
When either the left or right hydraulic cylinder (13
With the contraction of the steering clutch (12L or 13R), the swing arm (15) swings in the opposite direction, and the steering clutch (12L or 12R) is in the disengaged state.
R) will be entered and operated. Even if the 3-position switching valve (17) is maintained on the pressure supply side, if the 2-position switching valve (I9) is switched to reduce the pressure, the extended hydraulic cylinder (13L or 13R) will contract and switch. The steering clutch (12L or 12R) in this state will be engaged and operated.

The three-position switching valve (17), the two-position switching valve (19), and the pressure sensor (20) are all connected to the control device (C). And steering clutch (12L).

(12R), the 3-position switching valve (17), 2nd position I (, IJ switching valve (19) ) comprises a steering device for switching operation.

In the above-mentioned steering device, as shown in FIG. 1, when a left or right clutch disengagement command is given, the control bag f
(C) switches the 3-position switching valve (17) to the side that supplies pressure oil to the hydraulic cylinder (13L or 13R) that performs the clutch disengagement operation, and disengages the steering clutch (12L or 12R). Manipulate. Eventually, the oil pressure increases further, and the pressure sensor (20
), the two-position switching valve (19) is immediately switched to the pressure reducing side and the steering clutch (12L or 12L) is detected.
Enter and operate R). Then, when the set time (T) has elapsed, the two-position switching valve (19) is returned to the non-depressurizing side,
Disengage and operate the steering clutch (12L or 12R) again.

By returning the 2-position switching valve (19) to the non-pressure reducing side, the oil pressure rises again, but when the pressure sensor (20) detects that the set pressure has been reached, the 2-position switching valve (19)
9) Switch to the decompression side as before. In other words,
As long as the clutch disengagement operation command is not released, the two-position switching valve (19) is intermittently switched between the pressure reduction state and the non-pressure reduction state.

When a left or right clutch engagement operation command is given, the control device (C) returns the 3-position switching valve (17) to the neutral state, and at the same time returns the 2-position switching valve (engine 9) to the non-depressurizing state side. Return to normal position and engage the steering clutch (12L or 12R).

In this way, the steering clutches (12), (12
If R) is turned off intermittently, the driving force will be cut off intermittently and the driving speed of the traveling gear (4L) and (4R) will slow down, and if only one of them slows down, the speed of the aircraft (V) will slow down. A change of direction takes place. In this combine harvester, the cutting section (2
) is equipped with an automatic steering control function that automatically changes direction as the aircraft (V) moves forward, in order to maintain the lateral deviation position of the aircraft (V) at an appropriate position.

That is, when the amount of deviation of the cutting part (2) in the right lateral direction with respect to the stem culm (H) is large, a leftward latch cut operation command is given to slow down the traveling speed of the left traveling device (4L). , Aircraft (
V) turn slightly to the left. In addition, if the offset position in the left lateral direction is large, a rightward latch release operation command is given to slow down the traveling speed of the right traveling device (4R), and the aircraft (V
) to slightly change direction to the left. By this automatic steering control, the direction of the machine body (V) is changed so that the reaping part (2) is always maintained at an appropriate position with respect to the stem culm (H).

[Another example]

In the previous embodiment, the hydraulic cylinders (13L), (13
Steering clutch (12L), (1
Only the hydraulic cylinder (13L) is operated manually.
), (13R) has a traveling device (4L), (4R)
The hydraulic cylinder (13L),
By expanding and contracting (13R), the traveling device (4L), (4
In the previous embodiment, braking may be applied to the hydraulic cylinders (13L) and (13L).
The hydraulic cylinder (13L), (13
For example, a rimming switch may be provided near the swinging end of the swinging arm (15) for detection.

In the previous embodiment, the present invention is applied to a combine harvester, but the present invention can also be applied to other working vehicles such as a straw harvester.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings by the reference numerals.

[Brief explanation of drawings]

The drawings show an embodiment of the steering device for a working vehicle according to the invention, and FIG. 1 is a timing chart showing the switching operations of the 3-position switching valve and the 2-position switching valve, and the relationship between the pressure sensor and the oil pressure.
The figure is a hydraulic circuit diagram, Figure 3 is a schematic diagram showing the control configuration, and Figure 4 is a schematic diagram showing the control configuration.
5 is a side view of the combine harvester, and FIG. 6 is a timing chart showing the relationship between the switching operation of the 3-position switching valve and the oil pressure. (C)...Control means, (4L), (4R)
・・・・・・Traveling device, (12L), (12R)・
...Steering clutch, (13L), (13R)
......Hydraulic cylinder, (17)...3 position switching valve, (19)...2 position switching valve, (20
)...Sensor.

Claims (1)

[Claims] 1. The transmission systems for the pair of left and right traveling devices (4L) and (4R) are each provided with steering clutches (12L) and (12R) that are biased to return on the entry side. Pressure oil is alternatively supplied to steering hydraulic cylinders (13L) and (13R) that operate the steering clutches (12L) and (12R), respectively, and the hydraulic cylinders (13L) and (13R). Two states and these hydraulic cylinders (13L
), (13R) and a neutral state in which pressure oil is discharged from the hydraulic cylinders (13L) and (13R); an electromagnetically operated two-position switching valve (19) that can be freely switched between a state in which draining oil is stopped; and the hydraulic cylinder (1) to which the three-position switching valve (17) is commanded based on a clutch disengagement operation command.
Switch to supply pressure oil to 3L) and (13R),
The steering device for a working vehicle is further provided with a control means (C) for intermittently switching the two-position switching valve (19) between an oil drain state and an oil drain stop state, the hydraulic cylinder A sensor (
20), and the control means (C) includes:
The sensor (20) causes the hydraulic cylinder (13L
), (13R) has reached the stroke end, the work vehicle is configured to intermittently switch the two-position switching valve (19) to an oil draining state for a set time. steering device. 2. The sensor (20) is connected to the hydraulic cylinder (13L
), (13R) is a pressure sensor that detects the hydraulic pressure supplied to the working vehicle.