JPH0221002A - Work vehicle hydraulic circuit structure - Google Patents

Abstract

PURPOSE:To eliminate a shock at the time of shutdown by gradually reducing supply and drain flow quantities of operating fluid to and from a hydraulic actuator and setting a control valve in its neutral stop condition when an artificial operation tool is set in its neutral stop position. CONSTITUTION:A potentiometer 5 which detects a operation angle is provided on an operating lever 4, and signals from the potentiometer 5 is input to a control device 6 which gradually returns a control valve 2 to its neutral position and operates even when the operating lever 4 is swiftly set in its neutral position. Thereby, the speed of a hydraulic actuator 3 is gradually reduced when the hydraulic actuator 3 is stopped and a shock at the time of shutdown can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the configuration of a hydraulic circuit that drives a hydraulic actuator used in a work vehicle such as a construction machine or an agricultural vehicle.

[Conventional technology]

A backhoe, which is one type of work vehicle, is equipped with a hydraulic motor, which is one of the hydraulic actuators, to drive the rotation of the swivel table. There is a structure in which an operating lever as a human operating tool is mechanically interlocked and connected.

[Problem to be solved by the invention]

For example, if the control lever is returned to the neutral stop position during a turning operation by operating the control lever to the right or left turn side, the control valve is also immediately returned to the neutral stop position and operated to supply and drain hydraulic fluid to the hydraulic motor. stops, and the swivel base suddenly stops. As described above, when a heavy swivel table equipped with a hackhow device or the like suddenly stops, the swivel table swings left and right near the stop position due to its inertia. Therefore, in order to stop the swivel base without such a phenomenon, it is necessary to slowly operate the control lever from the right or left swivel side to the neutral stop position, and there is room for improvement in terms of operability. .

An object of the present invention is to provide a structure in which the hydraulic actuator is smoothly stopped without a shock even if the operating lever for the control valve for the hydraulic actuator is quickly returned to the neutral stop position.

[Means to solve the problem]

The feature of the present invention is that, in the hydraulic circuit structure of a work vehicle as described above, the control valve's artificial operating tool, which supplies and discharges hydraulic oil to the hydraulic actuator, is operated for a set time from the time when it is operated to the neutral stop position. There is provided a control means for gradually reducing the flow rate of hydraulic oil supplied to the hydraulic actuator or the flow rate of hydraulic oil discharged to the hydraulic actuator to bring the control valve into a neutral stop state, and its functions and effects are as follows.

[For production]

With the configuration described above, even if the operating lever is returned from the hydraulic oil supply/discharge side to the neutral stop position, the control valve for the hydraulic actuator is not in the neutral stop position at that point, and from that point on, the control valve for the hydraulic actuator is not in the neutral stop position. As the hydraulic oil supply flow rate or hydraulic oil discharge flow rate gradually decreases, the operation of the hydraulic actuator also gradually decelerates, and after a set time, the control valve reaches a neutral stop state, and then the hydraulic actuator completely stops. That's what I do.

〔Effect of the invention〕

As described above, even if the operating lever as a human operating tool is quickly returned to the neutral stop position, the hydraulic actuator does not stop immediately but slowly stops, so the operating lever slowly stops in neutral. The hydraulic actuator can now be stopped without shock without any special operations such as returning it to its original position.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Figure 1 shows the hydraulic circuit of a backhoe, which is one of the working vehicles. ) is configured to be sent to a hydraulic motor serving as a hydraulic actuator (3), and the control valve (2) is configured to rotate to a right rotation position (R), a left rotation position) and a hydraulic motor (3). ) and the neutral stop position (
It consists of three positions (N).

The control section (not shown) of the backhoe is equipped with a swing-operated operating lever as a manual operating tool (4).
A potentiometer (5) is provided to detect the operating angle of the operating lever (4), and a signal from the potentiometer (5) is input to a control device (6).

Next, to describe the relationship between the operating lever (4) and the control valve (2), the operating lever (4) is moved to the neutral stop position (N
o) to the right turning position (Ro) or left turning position (Lo)
As the device moves toward the side, the larger the amount of operation from the neutral stop position (No), the greater the degree of opening of the control valve (2) toward the right rotation position (R) or left rotation position (L). An operation signal is transmitted from the control device (6) to the control valve (2) so that. In other words, the greater the operating lever (4) is operated from the neutral stop position (No) toward the right turning position (Ro) or the left turning position (Lo), the faster the turning speed of the turning base becomes. In this way, the operating position of the operating lever (4) and the control valve (
The opening degree corresponds one to one with 2) when the operating lever (4) is operated slowly. (The range from time point (al) to time point (a2) in Fig. 2) and the operating lever detected by the potentiometer (5) (
4) If the operating speed exceeds the setting, for example, from time point (a3) to time point (a,) shown in Figure 2, the operating lever (4) is quickly rotated to the right from the neutral stop position (No). Even if the control valve (2) is operated to the rotation position (R”), the control valve (2) is
At step 4), the right turning position (R) is not reached, but after a slight delay, the right turning position (R) is completely reached at time (a5).

Conversely, even if the control lever (4) is quickly returned from the right rotation position (Ro) to the neutral stop position (No) from time (a6) to time (a,), the control valve (2) is the time point (a
Instead of returning to the neutral stop position (N) at step 7), the operation is performed to return to the complete neutral stop position (N) at time (a8) after a slight delay.

In the above control, the time (tI) when the swivel table starts turning (from time point (a3) to time point (a,)) is longer than the time when the swivel table stops (t2) (time (a6)).
) so that the turn is started relatively quickly from a stopped state, and
It is constructed so that it comes to a stop relatively slowly from a turning state.

[Another example]

In the above-mentioned embodiment, the control valve (2) itself functions to gradually reduce the hydraulic oil supply flow rate or the hydraulic oil discharge flow rate, but an electromagnetic proportional pressure reducing valve dedicated to flow rate control, which is separate from the control valve (2), is used. Alternatively, the flow rate may be controlled by duty control using an electromagnetic on-off valve.

Further, the present invention can be applied not only to a hydraulic motor but also to a double-acting hydraulic cylinder as the hydraulic actuator (3).

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 the drawing]

The drawings show an embodiment of the hydraulic circuit structure of a work vehicle according to the present invention, and FIG. 1 is a circuit diagram showing the linked state of the hydraulic motor, control valve, and operating lever in a backhoe, and FIG. 2 shows the operating position and operating position of the operating lever. 5 is a time chart showing the relationship between the opening degrees of control valves. (2)... Control valve, (3)... Hydraulic actuator, (4)... Human operating tool, (N)
・・・・・・Neutral stop position.

Claims (1)

[Claims] The artificial operating tool (4) for the control valve (2) that supplies and discharges hydraulic oil to the hydraulic actuator (3) is operated to the neutral stop position (N) and the hydraulic actuator (3) is operated within a set time. 3) A hydraulic circuit structure for a work vehicle, comprising a control means for gradually reducing the flow rate of hydraulic oil supplied to or discharged from the control valve (2) to bring the control valve (2) into a neutral stop state.