JPH02261905A - Hydraulic actuator operational structure - Google Patents

Abstract

PURPOSE:To lessen the delay of stop operation at the time of automatic stop operation by setting travel speed of a spool by the first operation means of a controller at a higher speed than the travel speed of the second operational means. CONSTITUTION:When an operating lever 14 is suddenly operated from the state where it is operated in the neighborhood of the maximum speed position R, L to a neutral stop position N, a spool of an electromagnetic proportional pressure reduction valve 3 is quickly slided to the maximum opening A1. That is, an electric current value for the pressure reduction valve 3 is dropped in a short time. Thereafter, the electric current value for the pressure reduction valve 3 is comparatively slowly dropped and the pressure reduction valve 3 comes to the totally closed position. Accordingly, during this time, hydraulic operating oil for a hydraulic motor 13 decreases and a swivel base stops slowly and smoothly. Consequently, the time required for the automatic stop or the motor 13 is generally shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic actuator used in a work vehicle such as a construction machine, and particularly to a stop operation structure for a hydraulic actuator.

[Conventional technology]

A backhoe, which is one type of work vehicle, is equipped with a hydraulic motor, which is one of the hydraulic actuators, for driving a rotating base, and its operating structure is as follows.

In other words, there is a directional control valve that switches the supply/discharge direction of the hydraulic oil supplied to the hydraulic motor to determine the direction of rotation of the swivel base, and a spool-type valve that controls the flow rate to change the rotation speed of the swivel base. By connecting the flow control valve in series, the flow control valve is operated so that the greater the amount of operation of the control lever for the directional control valve from the neutral stop position, the faster the rotation speed of the swivel base becomes. It is composed of

During manual operation using the control lever as described above, if you accidentally move the control lever from the maximum speed position to the neutral stop position, the swivel base will come to a sudden stop. In such cases, an automatic stop means is provided that disconnects the operating lever from the flow control valve and operates the flow control valve to the fully closed position at a relatively low constant speed, thereby stopping the swivel base with less shock. There are things we have.

[Problem to be solved by the invention]

In the case of the above-mentioned configuration, the flow rate to the hydraulic actuator and the operating position of the operating lever (corresponding to the opening degree of the flow control valve) are not in a perfect linear relationship, but as shown in Figure 2, the maximum speed position of the operating lever There is no change in the turning speed of the turning table in the vicinity. This is because in a spool-type flow control valve, there is a limit to the range of the flow it1 node by operating the spool, and even if the spool is operated to the open side beyond this range, the flow rate remains at the maximum flow rate and does not change. It is.

Then, at the spool opening that produces the maximum flow rate,
The reason why the maximum speed position of the operating lever is set to the valve opening side of the minimum opening degree (AI) is to open the flow control valve sufficiently at maximum speed and reduce pressure loss within the flow control valve. It is.

Therefore, in such a configuration, when the control lever is operated to the maximum speed position, the automatic stop means as described above is activated, and the opening degree corresponding to the maximum speed position is reached as shown in FIG. Even if the spool is operated to the valve closing side at a constant speed, there will be no change in the flow rate until the minimum opening degree (^1) is reached.
Only after this minimum opening degree (AI) is exceeded, the flow rate decreases and the swivel table begins to decelerate. As a result, the time required for automatic stopping of the swivel base becomes long as a whole.

Here, an object of the present invention is to reduce the delay in the automatic stopping operation as described above.

[Means to solve the problem]

A feature of the present invention is that the spool of the flow control valve that supplies and discharges hydraulic oil to the hydraulic actuator can be moved to an opening increasing range from the minimum opening that produces the maximum flow rate in the flow 1i adjustment range. In a hydraulic actuator operation structure in which a maximum movement range is set, a control device is provided that automatically operates the flow rate control valve to the valve closing side with a time delay based on a command to stop the hydraulic actuator that is being driven at the maximum speed. In addition, the control device includes a first operating means for sliding the spool, which is located at a position where the opening degree is larger than the minimum opening degree that produces the maximum flow rate, to the minimum opening degree, and a first operating means for sliding the spool from the minimum opening degree. and a second operating means for sliding the spool to the fully closed position, and the moving speed of the spool by the first operating means is set higher than the moving speed of the second operating means, and the operation thereof is as follows. And the effects are as follows.

[For production]

If configured as described above, the spool at a position where the opening degree is larger than the minimum opening degree will move relatively quickly to the minimum opening degree (during this time, the flow rate remains at the maximum and there is no change, and the hydraulic actuator does not decelerate. ). The spool that has been operated to the minimum opening degree is then operated at a relatively low speed to the fully closed position, and during this time the hydraulic actuator decelerates and comes to a stop.

Therefore, the time required to operate the spool to the fully closed position is longer than the configuration in which the spool is operated at a constant speed to the fully closed position at a position where the opening degree is larger than the minimum opening degree in the range that produces the maximum flow rate. becomes shorter overall.

〔Effect of the invention〕

As described above, by increasing the spool operating speed near the maximum speed where there is no change in flow rate and reducing wasted time, it is now possible to shorten the overall time required for the hydraulic actuator to automatically stop. , we were able to improve workability.

〔Example〕

Embodiments of the present invention will be described below using a backhoe, which is one type of work vehicle, based on the drawings.

Figure 1 shows the hydraulic circuit of a backhoe, and shows the pump (
A spool-type electromagnetic proportional pressure reducing valve as a flow rate control valve (3), a first control valve (4), and a second control valve (5) are connected in a line to an oil path (2) from 1). This first control valve (
4) is for supplying and discharging hydraulic oil to the hydraulic cylinder (7) that swings the backhoe device (6) shown in Fig. 4 from side to side, and the second control valve (5) is shown in Fig. 4. It supplies and discharges hydraulic oil to a hydraulic cylinder (9) that drives the dozer (8) up and down.

A pair of oil passages (10) from the electromagnetic proportional pressure reducing valve (3)
) is connected to a directional control valve (11). This directional control valve (11) switches the supply and discharge direction of hydraulic oil to a hydraulic motor serving as a hydraulic actuator (13) for driving the swivel base (12) as shown in FIG. It determines the turning direction, and as shown in FIG. 1, is biased to a neutral stop position (lla) by a pair of springs <1lc).

Next, the linkage structure between the operating lever (14), the directional control valve (11), and the electromagnetic proportional pressure reducing valve (3) will be described in detail. A pilot valve (16) for supplying and discharging pilot hydraulic oil for operation is provided, and a swing-operated operating lever (14) is provided.
and a pilot valve (16) are mechanically interlocked and connected via a link mechanism (17). In this case, the highest speed position (R) for rightward rotation and the highest speed position (L) for leftward rotation of the operating lever (14) are made to correspond to both stroke ends of the spool (not shown) in the pilot valve (16). There is.

A potentiometer (18) for detecting the position of the spool (corresponding to the angle of the operating lever (14)) is provided for the pilot valve (16), and a signal from the potentiometer (18) is sent to the control device (19). has been entered. As a result, the tilting angle of the operating lever (14) ((
The larger the R) side or (L) side), the larger the directional control valve (11).
An operation signal is issued from the control device (19) to the electromagnetic proportional pressure reducing valve (3) so that the flow rate to is increased. In other words, the structure is such that the larger the tilt angle of the operating lever (14) is, the faster the turning speed of the swivel table (12) becomes.

In this case, if the operating lever (14) is moved even slightly to the (R) side or (L) side from the neutral stop position (N), that is, if the spool of the pilot valve (16) is operated even slightly, the pilot valve Pilot hydraulic oil is supplied from (16) to the directional control valve (11).
) is switched.

Next, when the operating lever (14) that has been operated to the maximum speed position (R) or (L) is suddenly operated to the neutral stop position (N), the electromagnetic proportional pressure reducing valve (3) is slowly closed. The configuration for smoothly stopping the swivel base (12) will be described in detail. Before that, when performing such an operation using the electromagnetic proportional pressure reducing valve (3), the directional control valve (11) is operated to the neutral stop position (lla) before the electromagnetic proportional pressure reducing valve (3) is operated. If the oil supply/drainage is cut off, the flow rate cannot be controlled by the electromagnetic proportional pressure reducing valve (3), so even if the operating lever (14) is suddenly returned to the neutral stop position t (N), the directional control valve will not operate. (11) is delayed and the neutral stop position (lla
) will be described in detail.

As shown in FIG. 1, at the neutral stop position (16a) of the pilot valve (16), a throttle portion (16b) is provided that provides resistance to the pilot hydraulic fluid from the directional control valve (11). As a result, when the operating lever (14) is operated to the neutral stop position (N) from a state in which the directional control valve (11) is switched to one side, the pilot valve (16) is also moved to the neutral stop position (N) in conjunction with this. 16a). Then, the directional control valve (11) also has a spring (lie).
The pilot hydraulic oil is pushed toward the pilot valve (16) in an attempt to return to the neutral stop position (lla) due to the urging force of is delayed and returns to the neutral stop position (lla).

Next, the operation of the electromagnetic proportional pressure reducing valve (3) will be described in detail.

The relationship between the operating position of the operating lever (14) (corresponding to the opening degree of the flow rate control valve) and the amount of hydraulic fluid supplied to and discharged from the hydraulic motor (13) is as shown in FIG. In this way, the reason why the swivel speed of the swivel table (12) remains constant without changing at the maximum flow rate near the maximum speed positions (R) and (L) is in the spool type electromagnetic proportional pressure reducing valve (3). Fisheries are included in the range of flow rate adjustment by operating the spool.
This is because even if the spool is operated to the open side beyond this range, the flow rate will remain at the maximum flow rate and will not change.

At the opening of the spool that brings about the maximum flow rate, the operation lever (14) is moved to the valve opening side than the minimum opening (AI).
The maximum speed positions (R) and (L) are set by
This is to reduce pressure loss within the electromagnetic proportional pressure reducing valve (3) by sufficiently opening the electromagnetic proportional pressure reducing valve (3) at maximum speed.

Therefore, move the operating lever (14) to the highest speed position (R),
(L) From operating state to neutral stop position (N)
When the proportional electromagnetic pressure reducing valve (3) is suddenly operated, the spool of the electromagnetic proportional pressure reducing valve (3) is quickly (slided) operated to the above-mentioned minimum opening degree (AI).In other words, as shown in FIG.
(corresponds to the time point (at) to (a2), and the current value (i1) at the time point (a2) corresponds to the minimum opening degree (A1) in FIG. 2).

After that, as shown from time point (a2) to time point (a1) in Figure 3, the current value for the electromagnetic proportional pressure reducing valve (3) is relatively slowly reduced, and the electromagnetic proportional pressure reducing valve (3) is in the fully closed position. becomes. Therefore, during this time, the hydraulic motor (13)
As the amount of hydraulic oil decreases, the swivel base (12) comes to a slow and smooth stop.

[Another example]

In the above-mentioned embodiment, from time point (a2) to time point (a3) in FIG.
), but the current value may be reduced in a quadratic curve or stepwise in a stepwise manner.

Further, instead of providing the direction switching valve (11) and the flow rate control valve (3) separately, a valve mechanism that can perform direction switching and flow rate control at the same time may be used. The present invention can be applied not only to hydraulic motors but also to double-acting hydraulic cylinders.

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 actuator operation structure according to the present invention, in which Fig. 1 is a hydraulic circuit diagram of a backhoe, Fig. 2 is a diagram showing the relationship between the operating position of the operating lever and the flow rate to the hydraulic motor, and Fig. 3 4 is a time chart showing the current value for the electromagnetic proportional pressure reducing valve during automatic stop operation, and FIG. 4 is an overall side view of the backhoe. (3)...Flow rate control valve, (19)...
Control device, (A1)... Minimum opening degree in the range that provides the maximum flow rate. Figure 1

Claims (1)

[Claims] The spool of the flow control valve (3), which supplies and discharges hydraulic oil to and from the hydraulic actuator (13), can be moved to an opening increasing range from the minimum opening (A_1) that produces the maximum flow rate in the flow rate adjustment range. , the hydraulic actuator operating structure has a maximum movement range set, and closes the flow rate control valve (3) with a time delay based on a command to stop the hydraulic actuator (13) being driven at maximum speed. A control device (19) for automatic operation is provided on the valve side, and the control device (19) controls the spool, which is at a position where the opening degree is larger than the minimum opening degree (A_1) that provides the maximum flow rate, to the minimum opening degree. (A_1); and a second operating means that slides the spool from the minimum opening degree (A_1) to a fully closed position. A hydraulic actuator operating structure in which a moving speed is set higher than a moving speed by a second operating means.