JPH03234901A - Hydraulic circuit with regenerative function - Google Patents

Abstract

PURPOSE:To prevent pressure held in an actuator at a time of neutral position from lowering by elongating a seal margin of a spool at the cutoff position of a regeneration valve, holding the spool in the cutoff position with a multistage spring, and switch its present position to the communicating position by means of pilot pressure oil of a hydraulic pilot valve. CONSTITUTION:The spool 18 of a regeneration valve 8 provided in respective circuits 3, 4 of a hydraulic operation valve and an actuator 5 is held in the cutoff position by means of a multistage spring 19 for blockading an inlet port 20 and an intermediate port 21, and both ports 20, 21 are communicated together by means of pilot pressure toward a pressure receiving part 13. The intermediate port 21 is then communicated to an outlet port 24 via a check valve 22 and a seal margin l of the spool 18 is made in a length obtained by adding a standby zone l0 to an ordinary seal margin alpha. Still more, the multistage spring 19 is composed of first and second springs 25, 26, and first and second spring shoes 27, 28 are provided with gap L therebetween. Therefore, it is possible to prevent held pressure of the actuator 5 from leaking from the regeneration valve 8 in the neutral position of the operation valve and to make switching operation without any time difference.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic circuit having a regeneration function, which includes a regeneration valve in a connection circuit between a hydraulically operated valve and an actuator.

[Conventional technology]

A hydraulic system with a regeneration function that includes a regeneration valve in the connection circuit between the hydraulic operation valve and the actuator, and supplies return oil from the actuator to the actuator through the regeneration valve to prevent oil volume shortage when the actuator operates at high speed. circuit is known.

With such a hydraulic circuit, when the hydraulic operation valve is in the neutral position and the actuator is held, the load acting on the actuator will generate holding pressure in the holding side chamber, and this holding pressure will leak from the regeneration valve to the tank side. There is.

In other words, the regeneration valve has a spool slidably inserted into the valve hole of the valve body, and the holding pressure may leak from the gap between the valve hole and the spool.

For this purpose, leak reduction equipment is installed in the pipeline connecting the actuator's holding side chamber and the regeneration valve, the gap between the regeneration valve's valve hole and the spool is set small, and the sealing allowance (overlapping) between the spool and the valve hole is The above-mentioned leakage is reduced by setting a large value (distance).

[Problem to be solved by the invention]

If the first leak reduction method is used, the cost of the leak reduction equipment will be higher, and if the second leak reduction method is used, the gap between the spool and the valve hole has a limit due to machining accuracy, so leaks cannot be reliably prevented. Not only is this impossible, but the spool is susceptible to contamination by foreign matter, and due to thermal expansion, the spool cannot slide against the valve hole, resulting in malfunction. It takes a long stroke to move the actuator to the regeneration position, and it takes time to start regeneration, which may prevent the actuator from operating smoothly.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic circuit having a regeneration function that can solve the above-mentioned problems.

[Means and actions for solving the problem] In addition to increasing the sealing time between the spool and the valve hole when the regeneration valve is in the cutoff position,
With a structure in which the spool is held in the cutoff position by a multistage spring and slid to the communication position by pilot pressure oil, it is possible to reduce the leakage of the actuator's holding pressure from the regeneration valve, and also to switch the regeneration valve and the hydraulically operated valve at the same time. This allows for smooth operation.

〔Example〕

Pressure oil discharged from the hydraulic pump 1 is supplied to the chamber 6 of the actuator 5 and the holding side chamber 7 by the hydraulically operated valve 2 via the first and second pipes 3 and 4, and the first pipe 3 and the second pipe 4 is short-circuited to a regeneration pipe line 9 provided with a regeneration valve 8, and a counterbalance valve 10 is provided closer to the hydraulically operated valve 2 than the regeneration valve 8 in the regeneration pipe line 9.

The hydraulically operated valve 2 is held at the neutral position N by a spring force, and is switched to the first and second positions I and II by pilot pressure oil supplied to the first and second pressure receiving parts 11.12, and the regeneration valve 8
, the counterbalance valve 10 is held in the blocking position (2) by a spring force, and can be switched to the communicating position (2) by pilot pressure oil supplied to the pressure receiving parts 1B, 14, and the hydraulic pilot valve 15 supplies pilot pressure to each of the pressure receiving parts. Pressure oil is supplied.

As shown in FIG. 1, the regeneration valve 8 has a spool 18 inserted into the valve hole 17 of the valve body 16, and the spool 18 is held in the blocking position by a single multistage spring to connect the inlet port 20 and the intermediate port 21. The inlet port 20 and the intermediate port 21 are closed and communicated with the pilot pressure oil of the pressure receiving part 13, and the intermediate port 21 is communicated with the outlet port 24 through a passage 23 provided with a check valve 22. At the same time, the sealing Δg of the valve hole 17 and the spool 18 is the length of the normal sealing α plus the standby zone Δgo, and the multistage spring 19 has a standby zone with the first spring 25 for fine control matching. The set load of the first spring 25 is made larger than the set load of the second spring 26, and a gap ΔL is provided between the first spring receiver 27 and the second spring receiver 28. The gap ΔL is the same as the sealing Δg, and the pilot pressure oil in the step-up area of the hydraulic pilot valve 15 causes the spool 18 to resist the second spring 26 and close the gap ΔL1, that is, the seal. It is designed so that it slides by an amount of Δg.

In other words, when the hydraulic pilot valve 15 is operated by stroke S2, it outputs pilot pressure oil as shown in Fig. 3, and when the pilot pressure oil reaches P, the second spring 25 is compressed and the spool 18 strokes by Δg. The inlet port 20 and intermediate port 21 of the regeneration valve 8 are now open.
The stroke S2 from when the hydraulic pilot valve 15 is operated until the regeneration valve 8 opens is shorter than the conventional dead zone S3 and becomes the same dead zone as before (as shown in FIG. 4).

On the other hand, the spring constant of the spring 2b that pushes the spool 2a of the hydraulically operated valve 2 is the same as the spring constant of the first spring, and the opening area of the hydraulically operated valve 2 is such that the output pressure of the hydraulic pilot valve 15 is P.
It will open when l.

On the other hand, when the spring of the regeneration valve 8 is only the first spring 25, the output of the hydraulic pilot valve 15 is as shown in FIG. It opens when the pressure becomes P2 (Pl<P2), so
At that time, the stroke of the hydraulic pilot valve 15 becomes 83 and the dead zone becomes long, and even if the spool 2a of the hydraulic operating valve 2 slides and becomes the first or second device I, the regeneration valve 8
is not in the communicating position (3) and cannot be reproduced smoothly, so the actuator 5 cannot be operated smoothly.

In this way, by increasing Ω to the sealing distance between the valve hole 17 of the regeneration valve 8 and the spool 18, it is possible to reduce the leakage of the holding pressure of the actuator 5 from the regeneration valve 8 when the hydraulically operated valve 2 is set at the neutral position N. Ru.

When the hydraulic pilot valve 15 is operated, the hydraulic switching valve 2 is switched to the first position (■) and at the same time the regeneration valve 8 is set to the communication position (2), so that the return from the holding side chamber 7 of the actuator 5 is immediately transferred from the regeneration valve 8 to the chamber 6. The actuator 5 can be operated smoothly.

〔Effect of the invention〕

Since the sealing distance between the spool 18 and the valve hole 17 is made longer when the regeneration valve 8 is in the cutoff position, it is possible to reduce the leakage of the holding pressure of the actuator 5 from the regeneration valve 8 when the hydraulically operated valve 2 is in the neutral position.

Since the spool 18 of the regeneration valve 8 is held in the shutoff position by a multistage spring, even though the sealing distance of the regeneration valve 8 is lengthened, the pilot pressure oil is lowered when switching to the communication position, and the regeneration with the hydraulically operated valve 2 is performed. The valve 8 can be switched without any time difference, and the actuator 5 can be operated smoothly.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a sectional view of a regeneration valve, FIG. 2 is a hydraulic circuit diagram, and FIGS. 3 and 4 are charts showing operation patterns. 2 is an operating valve, 5 is an actuator, 8 is a regeneration valve, 9 is a regeneration pipe line, 15 is a hydraulic pilot valve, 16 is a valve body, 17
is the valve hole, and 18 is the spool. l versus lot pressure (kg/Cm)

Claims (1)

[Claims] A regeneration valve 8 is provided in the connection circuit between the hydraulically operated valve 2 and the actuator 5.
is provided, and has a structure in which the regeneration valve 8 and the hydraulically operated valve 2 are switched by pilot pressure oil from the hydraulic pilot valve 15, and when the valve hole 17 of the valve body 16 constituting the regeneration valve 8 and the spool 18 are in the cutoff position. A hydraulic system having a regeneration function characterized by having a structure in which the sealing distance of the spool 18 is made longer, the spool 18 is held in the cutoff position by a multistage spring, and the spool 18 is switched to the communication position using pilot pressure oil from the hydraulic pilot valve 15. circuit.