JPS5834204A - Oil pressure controller of agricultual machine - Google Patents

Abstract

PURPOSE:To simplify a circuit constitution of an oil pressure controller which operates two oil pressure actuators, by varying a load of a spring for setting working pressure in a relief valve according to pilot pressure, thereby providing only one relief valve. CONSTITUTION:An oil pressure controller which operates on a hydraulic cylinder 4 for a lift arm of a tractor and a hydraulic cylinder 8 for lifting rear wheels comprises a frame lifting valve 12, a position control valve 14, a drain check valve 15, an unload valve 16, a main relief valve 17 and others. The frame lifting valve 12 is connected in series to the upper side of a position controlling circuit so as to give operational priority to the rear-wheel lifting hydraulic cylinder 8. A spring 20 for setting working pressure in the relief valve 17 is secured to a movable piston 21 which is displaced by a pilot pressure so that when the pilot pressure is applied, the load of the spring may be enhanced for presenting higher working pressure to the relief valve.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic control device for agricultural machinery. ◎ For example, in the agricultural tractor shown in Fig. 1, the toe arm (5) for raising and lowering the working machine is driven by a hydraulic cylinder (4), and the rotary tilling device fii1il+ is connected and supported by the toe arm (5) for raising and lowering the working machine. Raise and lower the auxiliary work S mounting frame (6) equipped on the hydraulic cylinder (8) a.
JatcltiL、Operation 1IHj3ct#fftThere are 11 hydraulic operating levers +11 and -, which allow the toe arm range and auxiliary work equipment mounting frame (-) to be freely adjusted. In this case, the operating pressure of the lift arm hydraulic cylinder (4) is high and the frame hydraulic cylinder (8) is high.
) has a low operating pressure, so two types of relief valves with different operating pressures are required in the hydraulic control circuit.

For example, in Fig. 4, the position of the hydraulic cylinder (4) for the lift arm is controlled by the lever (9), and the position is controlled by the lever (9).
- Hydraulic cylinder (81st) is configured to be controlled on/off by a separate lever, and a switching valve controls the supply of pressure oil to each hydraulic path of both hydraulic cylinders (4) and (8). It was necessary to install a high-pressure relief valve in the hydraulic circuit for the tortoise and a low-pressure relief valve in the hydraulic circuit for raising and lowering the frame. In order to omit the switching valve @ in the above hydraulic control circuit, the frame elevating control valve (I) is configured to supply neutral drain oil to the toor hydraulic circuit, but in this case, Again, a high-pressure relief valve and a low-pressure relief valve are required.

An object of the present invention is to simplify the circuit configuration by incorporating a type of relief valve that can change the relief operation pressure chamber at any time in this simple hydraulic control system.

The following is an example of how the present invention can be applied to an agricultural tractor. Explanation will be given based on illustrative drawings.

Figure 1 shows paddy field tilling work in progress, with a rotary tiller 111 connected to the rear of a tractor +11 by a two-point linkage mechanism, and a lift arm (6) driven by a single-acting hydraulic cylinder (4). ) to support the tiller so that it can be driven up and lowered by its own weight.
A pair of left and right ground tail wheels O1 are attached to the frame l.
It is constructed so that it can be driven up and down by a hydraulic cylinder (8) with a t-4 motion.

The lift arm hydraulic cylinder (4) is used for a tractor (
The position of the lift arm (6 + ik) is controlled so that it automatically stops when the lift arm (6 + ik) is moved up and down to a height corresponding to the operating position of the lever (11) installed on the side of the pilot's seat. , another lever installed next to the cockpit.
These hydraulic cylinders (4) and (11) are connected to one control valve unit (11).

Figure 2 shows a hydraulic control circuit for both hydraulic cylinders (4).
Therefore, the frame lifting pulp 11 can be switched to 3 positions.
! ! , a position control pulp (14) operated via a position control 92 mechanism (11), and a position control pulp (14)
Drain check pulp holder which is integrated with 1, position control pulp (unloading pulp holder which operates with switching JLvc of 14, and main relief pulp tn) are built in. And the pulp for raising and lowering the frame 0@
It is connected in series with the n-position control circuit, and is configured so that frame raising/lowering operation takes priority.

In addition, the lift arm (51) and the position iwa link mechanism (l field) are linked by a feedback link (a), so that when the lever (switch) is operated in the t-υ direction, it is raised, and when it is operated in the (2) direction, it is lowered. It has become.

In addition, in the figure (lI [pressure oil supply path rc I & to the lift arm hydraulic cylinder (4)) is a check valve for preventing backflow.

Spring 1lIh for the operating pressure membrane chamber of the main relief valve Oη
, is supported by a movable piston @Xu that is displaced by pilot pressure, and when pilot pressure is applied, vC is increased due to the increased panel load, and is configured so that the operating pressure is switched to +)) -7 operating pressure. . A pilot oil passage A supporting this piston @υ and led out from the next cylinder is configured to be able to communicate with a pilot oil passage for operating the unloaded pulp α4keA.

Incidentally, FIG. 8 shows the specific structure of the control unit αri with the above configuration, and in the figure (PIri, t'umpbo), (
This is a connection boat to the alfl lift arm hydraulic cylinder (4), and a connection boat to the lbl・<(IIH frame lifting hydraulic cylinder (81).

According to the above configuration, when the unloading pulp door is closed, that is, when the lift arm hydraulic cylinder (4) is supplying pressure 3 and the wheels are not driven, the relief valve Q1)
The operating pressure is set low, and this operating pressure reaches a critical value (for example, J j
&9/j).

-'t, the position control valve Q41 is switched to the up position, pressure is built up in the pilot oil passage eJ4, the unloading pulp valve is closed, and the pressure oil is not supplied to the hydraulic cylinder (4). Then, the slope of the nokune receiver is displaced by the paddle pressure and switched to a high relief working pressure, and this working pressure is applied to the hydraulic cylinder (4) to a nine value (for example /JJ
It is set to 嬌-).

The present invention is applicable not only to agricultural tractors but also to hydraulic control devices for other agricultural machinery, such as a hydraulic cylinder for raising and lowering the harvesting section of a combine (high pressure operation) and a hydraulic cylinder for adjusting the insurance name (low pressure operation). It can also be used for control devices such as .

Furthermore, as the hydraulic actuator, one with suitable functions such as a hydraulic cylinder or a hydraulic motor may be selected and used.

As explained above, the present invention provides a pressure oil supply path t1 of a hydraulic circuit that controls the operating pipe of the first hydraulic actuator (4) that operates at a differential operating pressure. The second hydraulic actuator (8) is connected to the neutral oil drain path of the hydraulic circuit that controls the society. configured to operate preferentially to the first hydraulic actuator klK,
In addition, a relief valve (lη is connected to the pressure oil supply path to the hydraulic control circuit of the second hydraulic actuator (8), and this relief valve (lη is the same as that of the first hydraulic actuator).
The operating pressure of the cutter (cutter)? By changing the weight of the relief spring as the pilot pressure and automatically switching the IJ 17-7 operating pressure to the high pressure side and reversely, two campan pastes with different operating pressures are installed. - The first hydraulic actuator (4) that operates at high pressure and the second hydraulic actuator (4) that operates at low pressure can be protected universally without installing a relief valve, and switching of this relief operating pressure is easy. Since the dynamic and reversible tFJK is performed, there is no need for a dedicated switching operation, and the control device as a whole has high operability.

[Brief explanation of drawings]

Figure 1 illustrates an embodiment of the hydraulic control device for an agricultural machine according to the present invention. Figure 1 is an overall side view of an agricultural tractor in a state of plowing wet fields, Figure 2 is a hydraulic control circuit diagram, and Figure IE8 is a hydraulic unit. FIG. 4 is a vertical developed view of the same, and FIG. 4 is a hydraulic control circuit diagram of a comparative example of the 6th lamp. (4)...First hydraulic actuator, (8)...
...Second hydraulic actuator, aη...
relief valve. 1st @

Claims (1)

[Claims] ■ The pressure oil supply path of the hydraulic circuit that controls the operation of the first hydraulic actuator (4) which operates at a high operating pressure is controlled by the operation of the second hydraulic actuator (4) which operates at a lower operating pressure. The eighth hydraulic actuator (3) is connected to the neutral oil drain path of the hydraulic circuit.
) so that it operates preferentially over the first hydraulic actuator (4). a relief valve aηt- is connected to the pressure oil supply path to the hydraulic control circuit of the second hydraulic actuator ill;
The relief valve is configured as a pilot-type variable relief valve that automatically and reversibly switches the relief operating pressure to a high pressure side by changing the relief panel load as the operating pressure chamber pilot pressure of the first hydraulic actuator (4). Hydraulic control device for agricultural machinery. ■ The first hydraulic actuator (4) is a hydraulic cylinder that lifts and lowers the toe arm (・) of the tractor (1), and the second hydraulic actuator (8) is a rotary cylinder that is lifted and lowered by the lift arm III. Tillage device (3
2. The hydraulic control device according to claim 0, wherein the hydraulic control device is a hydraulic sill that drives up and down a frame (6) for attaching an auxiliary work amount installed in a vehicle. (2) The hydraulic control circuit for the first hydraulic actuator (4) is configured as a position control circuit that drives the first hydraulic actuator (4) to nine predetermined positions and automatically stops it depending on the operating position of the operating lever (Sl). Something? A hydraulic control device according to claim 0 or 0.