JPH0619165B2 - Work vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in device means of a hydraulic work device in a work vehicle including a hydraulic work device such as a backhoe work vehicle.

[Conventional technology]

Conventionally, in order to be able to artificially lightly operate the control valve for the hydraulic working device of the work vehicle, and yet to automatically control the hydraulic working device,
As shown in FIG. 6, a potentiometer (14) for converting the operation amount of the manual operation lever (17) into an electric signal is provided, and the electric signal from the potentiometer (14) and the automatic operation means (12) of the hydraulic working device (12) are provided. ), Based on the electrical signal given by
A control device (29) for operating the control valve (CV) via the proportional valve (28) was provided.

[Problems to be Solved by the Invention]

However, if a trouble occurs in the electrical system, the control system from the artificial operation lever (17) to the proportional valve (28) is entirely configured by electrical control, so the proportional valve ( 28), the control valve (CV) can no longer be controlled, the hydraulic working device runs away, and the
Even if (17) was returned to the neutral operation position, it could not be stopped.

An object of the present invention is to prevent runaway of the hydraulic working device and to easily stop the working device when a trouble occurs in the electric system.

[Means for Solving the Problems]

A characteristic configuration of a work vehicle of the present invention is that a control valve for controlling the hydraulic working device is provided in an oil supply path from a main hydraulic pump to the hydraulic working device, and the control valve is operated by a pilot operation hydraulic pilot operation. A device is provided in the pilot oil supply passage of the pilot hydraulic pump, and the pilot operating device is configured to change the pilot operating hydraulic pressure by manipulating a manual operating lever, and the pilot operating hydraulic pressure from the pilot operating device is changed to the control valve. An electric pressure reducing valve for returning at least a part of the pilot operating oil in the operating oil passage to the return oil passage to the hydraulic tank to reduce the pilot operating oil pressure is provided in the operating oil passage to An electric finger capable of outputting an operating current for controlling the operation of an electric pressure reducing valve Lies in comprising means, the effects thereof are as follows.

[Work]

In other words, it is possible to operate the control valve by reducing the pilot operating oil pressure by the electric pressure reducing type while the control valve can be lightly operated by the pilot operating oil pressure from the pilot operating device linked to the human operation lever. Even if the operation current from the electric command means is erroneously applied to the electric pressure reducing valve, the pilot operation hydraulic pressure higher than the instruction by the manual operation lever is not applied to the control valve.

In other words, even though the control target of the electric pressure reducing valve is the control valve, the control is mediated by pilot operating oil, so the virtual control state of the electric pressure reducing valve is Regardless of the operating state, the stop of the control valve depends on the control state of the pilot operating device that controls the supply state of the pilot operating oil that acts as an intermediary.

Therefore, if you return the artificial lever to the neutral operating position,
No pilot operating oil pressure is applied from the pilot operating device. Therefore, even if a trouble occurs in the electric command means and the electric system of the electric pressure reducing valve, the control valve is stopped.

〔The invention's effect〕

Due to the above-mentioned action, runaway of the hydraulic working device can be prevented, stability can be improved, and operation in an emergency can be easily performed, and work efficiency can be kept high.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 5, a traveling platform (3) equipped with a crawler type traveling device (1) and a dozer (2) is provided with a swivel base (4) and a driving unit (5). A backhoe with a dozer is constructed by attaching a backhoe device (7) to the swivel base (6) so that the orientation can be changed around the vertical axis (X) while mounting the 6).

A pair of traveling hydraulic motors (M1), (M2) for driving the left and right crawlers of the crawler type traveling device (1) separately, and a dozer arm
The traveling machine base (3) is provided with a dozer cylinder (C4) for vertically moving the dozer (2) by swinging (2a) up and down. Backhoe device (7) by swinging the swing motor (M3) and backhoe mounting bracket (8) that rotate the swivel base (6).
Attach the swing cylinder (C5) that changes the mounting direction of the to the swivel base (6), and attach the boom of the backhoe device (7).
(9) with the boom cylinder (C6) and arm (10)
Is configured to be rockably operated by the arm cylinder (C7) and the bucket (11) by the bucket cylinder (C8).

As shown in FIG. 2, the control valve (CV) for the boom cylinder (C6) is provided with an oil supply passage (R) for supplying oil from the main hydraulic pump (P1), and the control valve (CV) is provided.
Two pilot operating oil passages (L2), (L2) on a pair of operating parts
2 pilot operated valves (A1), (A
2) to the pilot hydraulic pump via the lock valve (13)
It is connected to the pilot oil supply line (L1) of (P2).

Then, the lock valve (13) is switched to the supply position to supply oil from the pilot hydraulic pump (P2) to the pilot operated valve side, and the two pilot operated valves (A1) and (A2) are manually operated by levers. By switching operation with (17), the pilot operating oil pressure from the pilot hydraulic pump (P2) is changed to a pressure that is directly proportional to the operation amount of the operating lever (17) and applied, and this oil pressure is used to control the control valve (CV). Can be operated individually for each cylinder drive operation, or the pilot control oil pressure can be released to switch the control valve (CV) to the neutral state due to the restoring spring (not shown). An operating device (16) is configured.

As shown in FIGS. 1 and 2, the pilot operating device (16)
At least a part of the pilot operating oil from the pilot operating device (16) is supplied to the hydraulic tank (19) in the operating oil passage (L2) that transmits the pilot operating oil pressure from the operating part (15) of the control valve (CV). There is an electric pressure reducing valve (21) for returning to the oil passage (20) to reduce the pilot operation hydraulic pressure, and an operation for controlling the operation of this electric pressure reducing valve (21). Electrical command means for outputting current (18)
Is provided in the automatic control mechanism that controls the operation of the boom (9).

From the electric command means (18), when the boom (9) rises and swings to a set height, the pilot operating oil pressure to the operating portion (15) is reduced to stop the rise of the boom (9). An operation current for reducing the pressure of the electric pressure reducing valve (21) is applied.

The electric pressure reducing valve (21) has a pump port (P) connected to the pilot operated valves (A1), (A1) in the pressure reducing valve body (22), as shown in FIGS. 3 and 4. Control valve (CV)
An output port (C) connected to the hydraulic tank (19) and a tank port (T) connected to the return oil passage (20) to the hydraulic tank (19) are provided.
A spool (23) for connecting and adjusting the two ports (P, C, T) is provided slidably, and an electromagnetic operation section (24) for slidingly operating the spool (23) is provided, and one end of the spool (23) is provided. A manual override section (25) is provided on the side so that it can be manually operated in an emergency.

That is, at the time of boost operation, (i) the electromagnetic operation part (24) is excited to apply a leftward force (F) proportional to the exciting current to the spool (23) and move it to the left.
(Fig. 3).

(Ii) By moving the spool (23) to the left, the pump port
(P) is connected to the output port (C), and pilot operating oil is supplied to the output port (C) .At this time, when the movement amount of the spool (23) is small, the output port (C) becomes the tank port.
It is connected to (T) (Fig. 4), and as the spool (23) moves to the left, the supply rate of pilot operating oil from the pump port (P) to the output port (C) increases. , Output port
The voltage is increased on the (C) side.

(Iii) The pressure of the output port (C) is transmitted to the pressure chamber (27) formed at the other end of the pressure reducing valve body (22) through the communication passage (26) in the spool (23), and the spool (23) ) And the cross-sectional area of), a rightward force (f) is generated.

(Iv) The spool (23) stops with the leftward force (F) and rightward force (f) applied to the spool (23) balanced, and the pressure at the output port (C) changes so that the electromagnetic operating unit (24) It is controlled to a value proportional to the exciting current to the.

During depressurizing operation, (i) contrary to the step-up operation, by decreasing the exciting current to the electromagnetic operating part (24), the leftward force (F) on the spool (23) decreases and decreases. The spool (23) moves to the right in proportion to.

(Ii) By moving the spool (23) to the right, the output port
(C) and the tank port (T) are connected (Fig. 4), oil is returned from the output port (C) to the tank port (T), and the pressure is reduced. Eventually, the pressure at the output port (C) is The pilot operating oil pressure is reduced to a value proportional to the exciting current to the operating section (24).

[Another embodiment]

The control valve (CV) may be for the turning motor (M3).

From the electric command means (18), when the boom (9) descends and swings to a set depth, an operation current is applied to the electric pressure reducing valve (21) to stop the descending of the boom (9). Alternatively, the swing control valve (CV) may be automatically controlled so that the swivel base (6) is automatically swung to a set position. Therefore, the boom cylinder (C6) may be automatically controlled. ) And the turning motor (M3) are collectively referred to as a hydraulic working device.

[Brief description of drawings]

1 shows a working vehicle according to the present invention, FIG. 1 is a block diagram showing an operating structure, FIG. 2 is a schematic diagram showing the operating structure, and FIGS. 3 and 4 are electric pressure reducing valves. FIG. 5 is an overall side view of the backhoe, and FIG. 6 is a block diagram of an operation structure showing a conventional example. (15) …… Operation part, (16) …… Pilot operation device, (17)…
... manual operation lever, (18) ... electrical command means, (19) ...
Hydraulic tank, (20) …… Return oil passage, (21) …… Electric pressure reducing valve, (CV) …… Control valve, (P1) …… Main hydraulic pump, (P2) …… Pilot hydraulic pump, (L1 ) …… Pilot oil supply passage, (L2) …… Operating oil passage, (R) …… Oil supply passage.

Claims (1)

[Claims] 1. A control valve (CV) for controlling the hydraulic working device is provided in an oil supply passage (R) from the main hydraulic pump (P1) to the hydraulic working device, and the control valve (CV) is pilot operated. A pilot operating device (16) that can be operated hydraulically is installed in the pilot oil supply passage (L1) of the pilot hydraulic pump (P2).
6) is configured so that the pilot operating oil pressure can be freely changed by operating the manual operation lever (17), and the pilot operating oil pressure from the pilot operating device (16) is operated by the operating portion (15) of the control valve (CV). To the operating oil passage (L2)
An electric pressure reducing valve (21) is provided for returning at least a part of the pilot operating oil in the operating oil passage (L2) to the return oil passage (20) to the hydraulic tank (19) to reduce the pilot operating oil pressure, and ,
A work vehicle provided with an electric command means (18) capable of outputting an operation current for controlling the operation of the electric pressure reducing valve (21).