JPH0632258A - Tractor hydraulic system - Google Patents

Abstract

PURPOSE:To provide a tractor hydraulic system where an expensive priority valve is unnecessary and an appropriate flow rate can be obtained in a hydraulic device even when the hydraulic devices for a loader, a back hoe and a three- point link are incorporated in a hydraulic system. CONSTITUTION:In a tractor hydraulic system where a first and second working devices 2, 3 to be hydraulically actuated are mounted on a tractor 1 provided with a hydraulic device 4 having a lift arm 4A, and the pressure oil from a pump P is fed to a control valve 11 of the hydraulic device 4 through a control valve 6 of the first working device 2 and a control valve 8 of the second working device 3, a switch valve 15 is provided in the circuit 14 between the return side of the control valves 6, 8 of the first and second working devices 2, 3 and the inlet side of the control valve 11 of the hydraulic device 4, and the switch valve 15 is provided with a throttle 24 where a small amount of the oil of the total flow amount is drained therefrom when switching is made to the oil flow to the hydraulic device 4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a hydraulic system for a tractor.

[0002]

2. Description of the Related Art A tractor equipped with a hydraulic device having a lift arm is equipped with a front loader (first working device) and a backhoe (second working device), and pressure oil from a pump is supplied to the tractor.
Hydraulic pressure of the tractor adapted to be sent to the control valve (third control valve) of the hydraulic device via the control valve (first control valve) of the first working device and the control valve (second control valve) of the second working device Systems are known in the art.

[0003]

In the hydraulic system of the tractor described above, since the loader, the backhoe, and the hydraulic system for the three-point link are the same hydraulic system, an excessive flow rate flows into the hydraulic system for the three-point link, There were issues such as pressure drop, rise, and shock when the implement rose.

In order to prevent this, if a priority valve is mounted, there is a cost problem because the valve is expensive. Therefore, an object of the present invention is to make it possible to flow an appropriate amount of flow to the hydraulic device without the need for an expensive priority valve even if the loader, backhoe, and hydraulic device for three-point link are the same hydraulic system.

[0005]

SUMMARY OF THE INVENTION The present invention is a lift arm.
The tractor 1 having the hydraulic device 4 having 4A is provided with the first and second working devices 2 and 3 which are hydraulically operated, and the pressure oil from the pump P is supplied to the control valve 6 of the first working device 2 and the second working device. In the hydraulic system of the tractor which feeds to the control valve 11 of the hydraulic device 4 via the control valve 8 of the device 3, the following technical measures are taken to achieve the above-mentioned object.

That is, according to the present invention, the switching valve 15 is provided in the circuit 14 between the return side of the control valves 6 and 8 of the first and second working devices 2 and 3 and the inlet side of the control valve 11 of the hydraulic device 4, The switching valve 15 includes
It is characterized by having a throttle 24 for draining a small amount of the total flow rate when switching to the flow of oil to the hydraulic device 4.

[0007]

[Function] When the backhoe (second working device) 3 is attached, the three-point link is not used. Therefore, the return from the second control valve 8 in the second working device 3 is returned via the switching valve 15. Drain the entire amount into tank T. Remove the second working device 3 from the tractor 1 and use the three-point link to connect the impules to the hydraulic device.
When moving up and down with 4, the first control valve 6 of the first working device 2
From the switching valve 15 to the inlet side of the switching valve 15
Switch to the state of Fig. 1 (B) and throttle a small amount of the total flow.
Drain through and send an appropriate amount to the control valve 11 of the hydraulic device 4.

[0008]

Embodiments of the present invention will be described in detail below with reference to the drawings. In FIG. 6, 1 is a wheel type tractor, to which a front loader 2 as a first working device and a backhoe 3 as a second working device are mounted, and a hydraulic device 4 for a three-point link is provided.

The loader 2 uses the lever 5 to move the first control valve 6
Operates hydraulically by operating the
By operating the second control valve 8 by 7, hydraulically operated. In FIG. 6, 9 indicates a driver's seat, 10 indicates a safety frame, and the backhoe 3 can be detached from the tractor 1 when the impule is attached by a three-point link. Figure 1
~ Referring to Fig. 4, the hydraulic device 4 is provided with a lift arm 4A, and is provided with the lift arm 4A by sending pressure oil to a piston fitted to the hydraulic cylinder by the control valve 11, and fitted to the hydraulic cylinder by the control valve 11. The lift arm 4A is moved up and down by sending pressure oil to the piston, which is mounted on the rear part of the vehicle body 1A.

The control valve 6 of the loader 2, the control valve 8 of the backhoe 3 and the third control valve 11 of the hydraulic device 4 are provided in the same hydraulic system as follows. As shown in Figure 1 (A),
The pump P driven by the engine 12 transfers the oil from the tank T, which is substantially the vehicle body 1A, through the line filter F, through the first control valve 6 of the loader 2 and the second control valve 8 of the backhoe 3. Liquid can be sent to the third control valve 11 of the hydraulic device 4.

The first control valve 6 and the second control valve 8 can be connected and separated by the male and female couplers 12A and 12B, and the second control valve 8 and the third control valve 11 are connected by the male and female couplers 13A and 13B. Separable, but when backhoe 3 is removed, male and female couplers
The first control valve 6 and the third control valve 11 are connected in series by connecting 12A and 13B. In the circuit 14 on the return side of the first and second control valves 6 and 8 and the input side of the third control valve 11, a switching valve 15 is provided on the side wall of the hydraulic device 4 in this embodiment.

The switching valve 15 has an import 17 and an out port 18 and a drain port 19 in a valve block 16, and a communication port 20 between the import 17 and the drain port 19 is provided with a rotary pool 21. The valve block 16 is attached to the side wall of the hydraulic device 4 with bolts 22,
The rotary pool 21 has a through hole 21 of the same area as the communication port 20.
A is formed in the radial direction, and by rotating the spool 21 by operating the operation lever 23, the spool is fully opened (drain position) shown in FIG. 4 (A), and the spool is fully closed as shown in FIG. 4 (B). In FIG. 1 (A), 25 is a relief valve of the same hydraulic system.

In the above embodiment, when the backhoe 3 is mounted and, for example, a groove excavation work is performed, it is not necessary to mount the three-point link. ) Switch to full open spool,
The male and female couplers 12A, 12B, 13A and 13B are respectively connected. In this state, the pressure oil from the pump P is sent to the second control valve 8 of the backhoe 3 via the first control valve 6, and the backhoe work is performed by the operation of the control valve 8 so that the second control valve 8 operates. The entire return flow is returned to the tank from the drain port 19.

On the other hand, when the backhoe 3 is removed and the three-point link is used for the inflection, the male and female couplers 12A and 13B are connected to form the series circuit 14, and the rotary pool 21 is shown in FIG. 1 (B). Thus, the posture is changed to have the diaphragm 24. In this state, the pressure oil from the pump P is delivered to the third control valve 11 of the hydraulic system 4 via the import 17 and the out port 18 via the first control valve 6 and, at this time, has the throttle 24. Therefore, a part of the total flow rate is released from the drain port 19 via the throttle 24, and an appropriate amount is sent to the third control valve 11.

When the rotary pool 21 is fully closed as shown in FIG. 4 (B), the total flow rate is sent to the three-point link, which means that even if a shock occurs when the instrument rises, the speed is increased. Can be for users who prefer fast ones. FIG. 5 shows the second embodiment of the present invention, which is the first embodiment described above.
In the embodiment, the throttle 24 of the rotary pool 21 is formed by the rotation amount thereof, whereas in FIG.
24 is formed separately.

The second working device may be a box sprayer or the like other than the backhoe.

[0017]

The present invention is as described above, and by draining a part of the total flow rate to a hydraulic system having a lift arm, pressure loss and shock can be achieved without using an expensive priority valve or the like. Occurrence can be prevented.

[Brief description of drawings]

1A is a configuration diagram of a hydraulic system, and FIG. 1B is a cross-sectional view of a switching valve.

FIG. 2 is a side view of a hydraulic device.

FIG. 3 is a rear view of the hydraulic device.

FIG. 4A is a sectional view of the switching valve in a fully open state and in a fully closed state in FIG. 4B.

FIG. 5 is a sectional view of a switching valve according to a second embodiment.

FIG. 6 is a side view of the tractor.

[Explanation of symbols]

 1 tractor 2 1st work device 3 2nd work device 4 hydraulic device 6 1st control valve 8 2nd control valve 11 3rd control valve 15 switching valve 24 throttle

Claims (1)

[Claims] 1. A hydraulic system (4) having a lift arm (4A).
A tractor (1) equipped with a hydraulically actuated first and second working device (2), (3) is provided, and pressure oil from the pump (P) is supplied to the control valve (1) of the first working device (2). 6), control valve of the second working device (3)
In the hydraulic system of the tractor for sending to the control valve (11) of the hydraulic device (4) via (8), the control valves (6), (8) of the first and second working devices (2), (3) A switching valve (15) is provided in the circuit (14) between the return side of the hydraulic system and the inlet side of the control valve (11) of the hydraulic system (4). A hydraulic system for a tractor, which has a throttle (24) for draining a small amount of the total flow rate when the flow is switched to the flow.