JPH0763244B2 - Agricultural tractor hydraulic system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an agricultural machine in which a port for hydraulic power is provided in a hydraulic oil supply passage from an electric position control valve to a hydraulic cylinder for a ground work device. The present invention relates to a hydraulic device for a tractor.

[Conventional technology]

In such a hydraulic device for an agricultural tractor, when supplying pressure oil to the port for extracting hydraulic power, first, the stopper attached to the guide groove of the lifting lever of the working depth setting device is released, and the end portion on the rising side is released. Allows rocking operation to. Then, by operating the lifting lever to the rocking end on the rising side, the position control valve control device is provided with an ascending signal of such a magnitude that the position control valve does not return to the neutral position by the feedback signal. The pressure oil is constantly supplied to the hydraulic cylinder for extension operation. Then, after maximally expanding and disabling further supply, the pressure oil constantly supplied is supplied to the port for extracting hydraulic power.

[Problems to be Solved by the Invention]

However, in the above-mentioned hydraulic device for agricultural tractor, since the stopper is fixed in the abutting state by using the bolt, it takes time and effort when releasing and setting again, and the resetting position is wrong and feedback is not effective. There is a risk that the position control is performed in this state and the relief operation is unnecessarily performed in the raised position.

In the present invention, attention is paid to such an actual situation, and it is an object of the present invention to supply pressure oil to a port for extracting hydraulic power by a simple operation and surely perform the original setting.

[Means for Solving the Problems]

The characteristic configuration of the present invention is that the control device for the position control valve is provided with, instead of the target level signal from the work depth setting device, a raising signal for forcibly raising the ground work device, and the forcibly raising means. And a switching setting means for switching and setting the level of the rising signal by the position control valve, wherein the switching setting means sets the level of the rising signal to a predetermined target level within the control range by the position control and also by the feedback signal. Is configured so that the target level can be set and switched to a level that does not return to the neutral position, and its action and effect are as follows.

[Work]

That is, when pressure oil is supplied to the hydraulic power take-out port, no matter what level the target level signal is set by the working depth setting device, the forced raising means and the switching setting means are By changing the target level of the forced rising means to a level above the rising limit in position control using, the position control valve is neutralized by the feedback signal instead of the target level signal from the working depth setter. A rising signal of a level that does not return to is given to the control device of the position control valve. Therefore, the position control valve will not return to the neutral position even by the feedback signal, and the continuous supply of pressure oil to the ground work equipment hydraulic cylinder will be maintained. The pressure oil is supplied to the power output port.

〔The invention's effect〕

Therefore, by making it possible to operate the means for giving the rising signal to the control device with one touch of a button,
The pressure oil can be quickly supplied to the port for extracting the hydraulic power. In addition, by releasing the rising signal, the original set state can be surely returned.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows an agricultural tractor to which the present invention is applied. This agricultural tractor is connected to a rotary ground working device (3) at the rear end of a traveling machine body (1) via a two-point link mechanism (2), and is driven up and down by a hydraulic cylinder (4) provided on the vehicle body side. Lift arm (5) and link mechanism (2)
And are erected and connected by a lift rod (6) to form a lifting device.

In this tractor, two types of automatic control are possible: position control for raising and lowering the ground work implement (3) to a set vehicle body level and plowing depth control for maintaining the ground work implement (3) at the set plowing depth. It has a control mechanism.

That is, a potentiometer (7) for detecting the ground work level of the ground work device (3) is attached to the base end of the lift arm (5), and a swingable rear cover (3a) is attached to the ground work device (3). ) Is attached with a potentiometer (8) for detecting the working depth of the device (3), and the vehicle body (1)
A control box (11) having a control device (10) built in the operating section (9) and a lifting operation lever (13) of the ground working device (3) are provided on the side of the seat (12). The control device (10) has a built-in microprocessor for controlling the position control valve (V) of the hydraulic cylinder (4), and performs the two types of automatic control according to a preset program.

As shown in FIGS. 1 and 2, a panel (11a) of the control box (11) has a switch (14) that can be switched between ON and OFF positions, and a dial operation type for setting a working depth. There is provided a plowing depth setting device (15), a dial operation type plowing depth control sensitivity setting device (16), and an upper limit switching switch (17) as upper limit switching setting means. The operating lever (13)
Is a uniaxial swing type, and a potentiometer (18) for setting a position is attached to the base end of the lever (13). By setting the operation lever (13) in the operation range (X), the position control is performed to raise and lower the working device (3) to the body level corresponding to the operation position of the lever (13). By setting the operation area (Y) linked to the area (X), the automatic tilling depth control state is set.
Two operations (X) and (Y) are discriminated by the output from the potentiometer (18).

That is, when the operation lever (13) having a control system as shown in FIG. 1 is set in the operation range (X), the target level signal from the potentiometer (18) and the lift arm (5) are attached. Control is performed based on the feedback signal from the potentiometer (7), the switch (14) is set to the ON state, and the operation lever (13) is set.
When set to the operating range (Y), the potentiometer (18)
The automatic tilling depth control is started by the target level signal from, and the control is performed based on the signal from the tilling depth setter (15) and the feedback signal from the potentiometer (8) that detects the swing of the rear cover (3a). Done.

If the operating lever (13) is set to the operating range (Y) while the switch (14) is set to OFF, the working device (3)
However, it descends to the limit where it can descend, and floats following the unevenness of the ground. This is the so-called floating state.

The control box (11) has a forced raising switch (19) as a forced raising means for raising the ground work device (3) to a set level in preference to the automatic plowing depth control.
Is provided. When the upper limit switch (17) is operated to the first operation position (A) and the switch (19) is pushed, the lamp (20) in the switch lights up and at the same time the ground working device (3) causes the upper limit switch ( In 17), when the level is raised to the vehicle body level within the control range preset by the position control and stopped, and the push operation is performed again, the lamp (20) turns off and the ground work device (3) returns to the original control state. Return to. Also, operate the upper limit switch (17) to the second operation position (B) to switch (1
When 9) is pressed, instead of the target level signal from the plowing depth setting device (15), the feedback signal is used to raise the position control valve (V) so that the position control valve (V) does not return to the neutral position, that is, the control valve (V). The control device (10) is given a signal to continue operating to the ascending side, the lamp (20) in the switch is turned on, and at the same time, the ground work device (3) ascends to the maximum ascending position where the hydraulic cylinder (4) is maximally extended. . When the push operation is performed again, the target level signal from the tilling depth setting device (15) is given to the control device (10) instead of the ascending signal, and the lamp (20) is turned off, and at the same time, the ground work device (3) is restored to its original state. Return to control state.

In the pressure oil supply passage to the hydraulic cylinder (4), a port (21) for extracting hydraulic power for supplying pressure oil to a hydraulic working device outside the machine is provided. As described above, if the upper limit switch (17) is operated to the second operation position (B) and the switch (19) is pushed to expand the hydraulic cylinder (4) to the maximum extent, the pressure oil supplied Can be supplied to another hydraulic device (22) connected to the port (21) for extracting hydraulic power.

The plowing depth sensitivity setting device (16) is also used as a switch for arbitrarily raising and lowering the ground work device (3), and the operation position (D),
By operating (M) and (U), the ground work device (3) is lowered, brought into a neutral state, and raised.

[Another embodiment]

In implementing the present invention, the upper limit changeover switch (17) may be of a dial operation type so that the operator can freely set the level with respect to the vehicle body at the first operation position (A).

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show an embodiment of a lifting control mechanism of an agricultural tractor according to the present invention. Fig. 1 is a circuit configuration diagram of a control device, Fig. 2 is a plan view of a control box, and Fig. 3 is a rear side view of an agricultural tractor. FIG. 4 is a plan view showing a control box of another embodiment. (4) ... hydraulic cylinder for ground working device, (10) ... control device, (15) ... working depth setting device, (17) ... switching setting means, (19) ... forced lifting means, ( 21) …… Port,
(V) ... Position control valve.

Claims (1)

[Claims] 1. A hydraulic system for an agricultural tractor, wherein a port (21) for extracting hydraulic power is provided in a pressure oil supply path from an electric position control valve (V) to a hydraulic cylinder (4) for a ground work device. Therefore, instead of the target level signal from the working depth setting device (15), the controller (10) of the position control valve (V) outputs a rising signal for forcibly raising the ground working device. Means (19) and switching setting means (17) for switching and setting the level of the rising signal by the control rising means (19) are provided, and the switching setting means (17) sets the level of the rising signal to the position. The target level is set to a predetermined target level within the control range of the control and a level at which the position control valve (V) does not return to the neutral position even with the feedback signal. Conversion can be configured to a hydraulic apparatus for agricultural tractors are.