JPH035530A - Hydraulic system of work vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a work vehicle equipped with a service port for extracting hydraulic pressure and a manually operated service valve that controls a hydraulic actuator connected to the service port. Regarding hydraulic equipment.

[Conventional technology]

Conventionally, in the above-mentioned work vehicles, there are two types: an automatic restoration type in which the service valve automatically returns to the neutral position, and a position holding type in which the service valve is held in the actuator drive position without requiring manual maintenance operations. was.

[Problem to be solved by the invention]

Conventionally, in the automatic restoring type, when driving a motor-driven work device such as a cutter or earth breaker using the service port, the service valve that has been switched to the actuator drive position should not be restored to the neutral position. There are disadvantages in that it takes time and effort to hold the service valve, and a stopper that holds the service valve in the actuator drive position is activated, and it takes time and effort to release the stopper when the drive of the working device is stopped, resulting in a delay in stopping. In addition, with the position holding type, when using a service port to operate a work device with a cylinder such as a packet with a clamping function, the service valve can be quickly switched when adjusting the position of the work device. There was an inconvenience that it was difficult to make fine adjustments.

An object of the present invention is to provide a working device that can be operated appropriately regardless of whether the working device is a motor type or a cylinder type.

[Means to solve the problem]

In the hydraulic system for a work vehicle according to the present invention, in order to achieve the purpose, the service valve is provided with a first actuator drive position and a second actuator drive position located between the first actuator drive position and the neutral position. Prepare,
A spring is provided to switch and bias the service valve in the second actuator drive position to the neutral position, and a detent mechanism is provided to hold the service valve in the first actuator drive position. The functions and effects thereof are as follows.

[For production]

Even if the service valve is switched to either the first or second actuator drive position, hydraulic pressure is supplied to the hydraulic actuator connected to the service port, and the actuator can be driven.

When the service valve is switched to the second actuator drive position, when the operation to maintain the second actuator drive position is released, the spring automatically restores the service valve to the neutral position, and the service valve is automatically restored to the neutral position when the service valve is switched to the first actuator drive position. In some cases, the detent mechanism causes the service valve to remain in the first actuator drive position without any manual action to maintain the position.

In the detent mechanism, the service valve automatically operates as the service valve switches to the first actuator drive position,
By applying an operating force equal to or greater than a set value in the direction of switching the service valve to the neutral position, the engagement can be automatically released to enable valve switching. That is,
The holding means can be switched to perform holding operation or release holding by simply performing an operation for switching the service valve.

〔Effect of the invention〕

When driving a motor-type work device, the service valve is switched to the first actuator drive position and the valve is operated to drive the work device, and furthermore, the valve position can be held or released quickly by simply switching the valve. This makes it possible to drive the working device without having to take the trouble of holding the valve, and to stop the driving quickly just by switching the valve, making it possible to work easily and safely.

When operating cylinder-type work equipment, turn the service valve into the second
By operating the valve that switches to the actuator drive position and operates the work equipment, it is possible to automatically restore the service valve to neutral, allowing for more efficient work by accurately and easily aligning the work equipment. It became so.

〔Example〕

Next, examples will be shown.

As shown in Fig. 2, the front wheel (1) and the shovel device (
2), a rear wheel (3), and a driving unit (4).
, a driving part (5), a backhoe device connecting part (6), etc. are connected to the rear vehicle body so as to swing relative to each other around the vertical axis (X), and the front vehicle body is controlled by the steering cylinder (C+). The wheel loader is configured to perform steering operation by swinging the rear vehicle body, thereby configuring a folding-body type wheel loader.

A service port (7) is provided at the rear of the rear vehicle body, and an asphalt cutter is attached to the backhoe device connected to the rear vehicle body.
When a motor-driven work device such as an earth breaker is attached, or a work device with a cylinder such as a multi-purpose packet that can be used for clamping work is attached, the hydraulic pressure from the hydraulic pump (P) for driving the excavator device is connected to the service port. (7
) so that it can be taken out to drive and operate the working equipment. The hydraulic circuit for this purpose is constructed as shown in FIG.

In other words, the tilt valve (v2) connected to the tilt cylinder (C2), the lift valve (v3) connected to the lift cylinder (C3), and the service valve (V) connected to the service port (7) are connected to a center bypass type multiple series. It is formed into a valve and connected to a hydraulic pump (r').

The service valve (V) is moved to a neutral position (n), two first actuator drive positions (aI), (a-), and one first actuator drive position (al) by manual operation of a sliding spool (not shown). and a second actuator drive position (b+) located between the first actuator drive position (C2) and the neutral position (N), and a second actuator drive position (b2) located between the other first actuator drive position (C2) and the neutral position (N). It is configured to be switched to a total of five operation positions, and when operated to one of the first actuator drive positions (a,) and the second actuator drive position (b,), it is connected to the service port (7). The hydraulic actuator (A) is driven in the normal operating direction, and when the other first actuator drive position (C2) and second actuator drive position (b2) are operated, the hydraulic actuator (8) is driven in the reverse operating direction. It is configured to be driven.

The springs (8a) and (8b) and the detent mechanism (9) are applied to the sliding spool, and the springs (8a) and (8b) move the sliding spool to a position that reveals the neutral position (n). The detent ball constituting the detent mechanism (9) is configured to be biased to slide, and when the sliding spool is in a position to reveal the second actuator drive positions (b,) and (b2). (9a) is in a position removed from the engagement grooves (9c) and (9d) of the spool side member (9b), and the sliding spool reveals the first actuator drive positions (a,) and (C2). When the detent ball (9a) is in position, the spool side member (9b)
It is configured to engage in the engagement groove (9C) or (9d) of. That is, when the service valve (V) is at either of the second actuator drive positions I(tz), (bz), the detent mechanism (9) is in the inactive state and the spring (8a) or (8b) (V)
The structure is such that the switch is switched to the neutral position (n) and energized.

Furthermore, when the service valve (V) is operated to any of the first actuator drive positions (a1) and (C2), the detent mechanism (9) automatically becomes activated and the springs (8a) and (8b) ) to hold the service valve (V) in the first actuator drive position (a, ) or (C2), and
, ) or (C2), when a switching operation force that exceeds the set value in the direction of switching to the neutral position side is applied, the detent mechanism (9) operates to release the holding, and the service valve (V) It is configured to enable switching between the two.

In other words, the hydraulic actuator (A) is controlled by the manual switching operation of the service valve (V). Then, by switching the service valve (V) to the second actuator drive position (bl) and (b2) and operating the valve to drive the actuator, the service valve (V) can be moved to the neutral position ( n) and the hydraulic actuator (A) stops, and if the service valve (V) is switched to the second actuator drive position (al) and (C2) and the valve operation is performed to drive the actuator, The hydraulic actuator (A) maintains its operating state even if no valve maintenance operation is performed.

In addition to wheel loaders, the present invention can also be applied to various work vehicles such as backhoes and agricultural tractors.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

The drawings show an embodiment of the hydraulic system for a work vehicle according to the present invention,
FIG. 1 is a hydraulic circuit, and FIG. 2 is a side view of the entire wheel loader. (7)...Service port, (8a), (
8b)...Spring, (9)...Detent mechanism, (^)...Hydraulic actuator,
(V)・・・・・・Service valve, (a+), (
a-)...First actuator drive position, (b
+), (bz)...second actuator drive position, (n)...neutral position.

Claims (1)

[Claims] A service port (7) for extracting hydraulic pressure, and a hydraulic actuator (A) connected to this service port (7).
), the hydraulic system for a work vehicle is equipped with a manually operated service valve (V) for controlling the service valve (V).
), the first actuator drive position (a_1), (a_2
), and this first actuator drive position (a_1)
, (a_2) and the neutral position (n), the second actuator drive positions (b_1), (b_2) are provided.
2) the service valve (V) in the neutral position (
n) are provided with springs (8a) and (8b) for biasing the switch, and a detent mechanism (9) for holding the service valve (V) at the first actuator drive position (a_1) and (a_2). A hydraulic system on a work vehicle.