JPH01306326A - Control device for oil pressure in tractor - Google Patents

Abstract

PURPOSE:To eliminate the need for a pressure control valve and shunt valve on each hydraulic operation part and to reduce the number of parts by arranging a proportional pressure control valve capable of changing a pressure control value within a fixed range on a pipe line and controlling this valve by a CPU. CONSTITUTION:A pressure oil 4 is forcibly fed in a main pipe line 3 by a hydraulic pump 2 and shunted by a shunt valve 5. An adjusting flow port 12 and excess flow port 13 are provided on the shunt valve 5. The pressure oil 4 discharged from the excess flow port 13 is passed through the main pipe line 3, operating a lift arm cylinder 9 by reaching to a main circuit 10. The pressure oil 4 discharged by controlling the flow by the adjusting flow port 12 is passed through a pipe line 14 and flowed into a proportional pressure control valve 15. The proportional pressure control valve 15 is formed so as to change the pressure control value within a fixed range, controlling the oil pressure by being transmitted with an electric signal from a CPU 16.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a hydraulic control device for a tractor, and in particular, a hydraulic control device for controlling a plurality of hydraulic operating parts that are not operated simultaneously using a single proportional pressure control valve. The present invention relates to a hydraulic control device that can control the hydraulic pressure.

"Prior Art" A conventional hydraulic control system for this type of tractor will be described with reference to FIG. 3 of the attached drawings. In the figure, (1) is a pressure oil tank;
(2) shows the hydraulic pump, and (3) shows the main pipe.

A flow divider valve (5a) that divides the pressure oil (4) into two circuits is arranged in the main pipe (3), and the flow divider valve (5a) supplies a constant adjusted flow pij to the PTO output clutch (6). The other pressure oil (4) is sent to the pressure control valve (7a) and the main pipe (3a
).

In addition, a flow divider valve (5b) is arranged in this main pipe (3a) 17 to further divide the flow into two circuits, and pressure oil (4) with an adjusted flow rate is sent under pressure to the pressure control valve (7b) of the front wheel double speed transmission clutch (8). The remaining pressure At+ (4) is transferred to the lift cylinder (9
) is shunted to the main circuit θ0). Then, a switching valve (mountain) that can arbitrarily control the oil pressure is connected to the pressure control valve ('1a), and the switching valve (Ila) is remotely controlled to
The TO clutch (6) is operated by the hydraulic cylinder (6a) (Also, a switching valve (llb) is similarly connected to the pressure control valve (7b), and the switching valve (Ilb) is operated to double the front wheel speed. Clutch operation was performed by activating the 411-pressure cylinder (8a) of the Mi-Nongyon clutch (8).

When installing equipment that must be operated by hydraulic control, such as a hydraulic reverse transmission (not shown), the main pipe (
A diverter valve was additionally installed in 3) to divert the pressure oil (4).

[Problems to be Solved by the Invention] As mentioned above, conventional hydraulic operating devices such as PTO output clutches are each connected to the main pipe line of a hydraulic control device via a flow divider valve, and are supplied with pressure oil. It required a flow divider valve and a pressure control valve. Therefore, the mechanism becomes complicated, and sufficient pressure oil capacity is required to divide the pressure oil through a large number of flow divider valves disposed in the main pipe. Therefore, a technical problem arises that must be solved in order to simplify the mechanism and provide an inexpensive hydraulic control device, and it is an object of the present invention to solve this problem.

[Means for Solving the Problems] The present invention was proposed to achieve the above object, and includes a proportional pressure control valve disposed in a pipeline of a hydraulic control device, and a A plurality of hydraulic actuating parts each having a different optimum oil pressure are connected in parallel, and when one of the hydraulic actuating parts is hydraulically actuated, the pressure value of the proportional pressure control valve is changed to provide an appropriate pressure for the hydraulic actuating part. It is an object of the present invention to provide a hydraulic control device for a tractor, characterized in that a CPU is provided with a control section that outputs operation commands to control hydraulic pressure.

[Function] This invention provides a tractor equipped with a plurality of hydraulic operating devices such as a PTO clutch and a front wheel double speed clutch, in which the pressure oil pipes of the two devices are connected to form one pipe, A proportional pressure control valve is provided between the conduit and a regulating flow port of a branch valve disposed in the main conduit. The pressure control valve is configured to be able to change the pressure control value by receiving an electric control signal from the CPU. Therefore,
A rotary or other ground-based work machine connected to the tractor is PT.
When driven by the O output, the CPU sends a control signal to the proportional pressure control valve to perform hydraulic control so that the hydraulic pressure is appropriate for operating the PTO clutch. Further, when the PTO clutch is disengaged and the front wheel double speed mission clutch is activated to perform double speed turning, the CPU issues a command to change the oil pressure value, and the pressure control value of the proportional pressure control valve is set to the appropriate oil pressure value of the front wheel double speed mission clutch. Make it so that

In this way, it is possible to deal with two systems of h-port pressure actuating parts having different appropriate oil pressures.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2 of the attached drawings. For convenience of explanation, conventionally known techniques will also be explained at the same time. In the figure, (1) is an oil tank, (2) is a hydraulic pump, and (3) is a main pipe. /Vh
The pressure oil (4) in the tank (1) is sucked up by the hydraulic pump (2) and fed under pressure through the main pipe (3).
The flow is divided by a flow divider valve (5) connected to the flow. The flow dividing valve (5) has an adjustment flow port 02) 8 that can adjust the pressure oil discharge amount.
1 (2) and a surplus flow port 03) which discharges surplus pressure oil when the discharge amount of pressure oil (4) of the hydraulic pump (2) is greater than the discharge amount set to the adjustment flow port 02). ing.

Pressure oil (4) discharged from the surplus flow port 03)
passes through the main conduit (3), reaches the main circuit (10), and operates the lift arm cylinder (9). Further, the pressure oil (4) discharged by controlling the flow rate through the regulating flow port (1/I) flows into the proportional pressure control valve (1'9) through the pipe (1/I). One is formed so that the pressure control value can be changed within a certain range, and receives an electric signal from the CPU (+6) to control the hydraulic pressure. The switching valve (Ilb) of the front wheel double-speed transmission clutch (8) is connected to the pipe (<r'?) for clutch operation. Also, the switching valve of the PTO clutch is connected to the discharge port pipe (r7). (lla) is the switching valve (Il) of the front wheel double speed transmission clutch (8).
b) is connected in parallel with the proportional pressure control valve (two systems of hydraulic actuating parts are connected to one).

Then, when connecting a working machine such as a rotary (one) to this tractor with a link mechanism, and driving the working machine by the PTO output of the tractor (lE6) to perform ground work, the PTO operating lever is Set (a) to “on, 1.

In such a case, the CPU (+6) calculates an appropriate control value 17 based on preset data and transmits an electric signal to the proportional pressure control valve (1).Therefore, the proportional pressure control valve θ is Control the pressure to the appropriate oil pressure of the PTO clutch (6) 7, and then operate the switching valve (Ila) to press the PTO clutch (6) with the hydraulic cylinder (6a) and take out the PTO output. I can do it.

Then, the PTO clutch (6) of the tractor is turned on and the rotor 1 is driven by the PTO output. Turn it "off" to stop the drive of the rotary. Then, the main circuit (10) of the hydraulic control device
The lift arm cylinder (9) connected to the CP
, U(+6) controls the pressure control value of the proportional pressure control valve (one) to the appropriate oil pressure value of the front wheel double speed transmission clutch (8).Then, the switching valve of the front wheel double speed transmission clutch (8) (llb) is activated and the hydraulic cylinder (
Pressure oil (4) is fed to 8a), and the front wheel double speed mission clutch (8) is turned on, allowing the tractor to turn at double speed.Thus, turning is completed. When starting ground work again using the ground work machine, turn the front wheel double speed transmission switch (21) to 1 off.

Then, the front wheel double speed transmission clutch (8) switching valve (
llb) operates and pressure oil (
4), the front wheel double speed transmission clutch (8) becomes "off". Therefore, the lift arm cylinder (9)
When the hydraulic control valve (19) is lowered and the PTO operating lever (to) is turned on, the proportional pressure control valve (1) changes the hydraulic control state again according to the control signal from the CPU (16). corresponds to the optimum IL oil pressure of the PTO clutch (()).At this time, the CP u(+@+,:
A PTO priority circuit is installed so that when the PTO operating lever (a) is turned on, the front wheel double speed mission switch (21) is automatically turned off. . Furthermore, the present invention should not be limited to the above two configurations; for example, it is also possible to connect a hydraulic actuator such as a hydraulic reverse clutch in parallel with the front wheel double-speed transmission clutch, and the present invention can also be applied to the ground-based work machine. Able to adapt.

[Effects of the Invention] As described in detail in Section 2-Examples, the present invention provides a proportional pressure control system that can change the pressure control value within a certain range in a hydraulic control device for hydraulic pressure control equipment. A pressure control valve is provided, and the proportional pressure control valve can be controlled by the CPU. A plurality of hydraulic operating sections, which are not operated at the same time and have different appropriate hydraulic pressure values, are connected in parallel to the proportional pressure control valve. Therefore, the number of parts can be reduced without requiring a pressure control valve and a flow divider valve for each hydraulic operating section. In addition, by reducing the number of diverter valves, the number of diverter pipes is also reduced, making it possible to simplify the configuration of the hydraulic control device.Furthermore, the reduction in the number of pipes frees up pressure oil capacity. This invention exhibits various effects such as the above, and can provide a hydraulic control device at a low cost.

Therefore, this invention can be modified in various ways without departing from the spirit of the invention, and it goes without saying that this invention extends to such modifications.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, FIG. 1 is a hydraulic circuit diagram, and FIG. 2 is a side view of a tractor to which a rotor is connected. Further, FIG. 3 is a hydraulic circuit diagram of a conventional example. (5)・・・・・・Diversion valve (6)・・・PTO clutch (8)・・・Front wheel double speed mission clutch (10
)... Main circuit (Ila) (Ilb) - switching valve (1 piece... Proportional pressure control valve (16)... CPU

Claims (1)

[Claims] A proportional pressure control valve is disposed in the pipeline of the hydraulic control device, a plurality of hydraulic operating parts having different optimum oil pressures are connected in parallel to the proportional pressure control valve, and one of the hydraulic operating parts is hydraulically operated. Hydraulic control in a tractor, characterized in that a CPU is provided with a control unit that changes the pressure value of the proportional pressure control valve and outputs an operation command to the hydraulic operating unit so that the hydraulic pressure is appropriate. Device.