JPH04224302A - Inversion prevention valve - Google Patents

Abstract

PURPOSE:To eliminate internal leakage and increases certainty of operation by providing constitution in such a way that control of bypass flow rate is carried out by a spool and that control of spool change-over speed is achieved by restriction of a pilot passage in an inversion prevention valve which prevents inversion operation immediately after a hydraulic actuator is stopped. CONSTITUTION:When a change-over valve 36 is changed over to the neutral position to stop a hydraulic actuator 33 during its rotation, the hydraulic actuator 33 tries to continue its rotation due to the inertia of a driven body, so that hydraulic pressure on an inlet 38 side rises and flows into the outlet 39 of the hydraulic actuator through a brake valve 35 to provide braking force. Although the hydraulic actuator 33 and the driven body stop, high pressure occurs due to pumping action of the hydraulic actuator 33 caused by the inertia of the driven body. The high pressure oil is led into a spring oil chamber 24 through a pilot passage 26 provided with a restriction 14 which communicates with an outport 22 and presses a spool 2 together with a spring 10 to return it to the neutral position, thus preventing inversion of the hydraulic actuator 33.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] When controlling a hydraulic actuator used in a swing device such as a hydraulic power excavator or a truck crane, the present invention switches a switching valve to a neutral position, and then activates the hydraulic actuator through a brake operation by a brake valve. The present invention relates to a reversal prevention valve that prevents reversal operation immediately after the stop.

0002

2. Description of the Related Art When a hydraulic actuator used in such a swing device is switched to a neutral position in order to stop it during rotation, the hydraulic actuator does not stop immediately;
Due to the inertia of the driven body, it attempts to continue rotating further. However, since both the inlet and outlet of the hydraulic actuator are already closed at the neutral position of the switching valve, the hydraulic pressure on the inlet side increases and flows to the outlet of the hydraulic actuator through the brake valve, which is a relief valve, and acts against the hydraulic actuator. It operates as a brake operation by a brake valve. At this time, after the brake is applied for a certain period of time, the hydraulic actuator and the driven body stop, but due to the inertia of the driven body, high pressure is generated on the outlet side of the hydraulic actuator due to the pumping action of the hydraulic actuator when it stops, causing the hydraulic actuator to reverse. . This reversal was also dangerous.

When such a conventional hydraulic actuator is stopped, a reversal prevention valve that prevents reversal operation immediately after the stop has a movable seat and a poppet, as shown in Japanese Patent Application Laid-Open No. 57-25570, for example. When the hydraulic actuator is stopped, either the movable seat or the poppet is pushed by the spring and opens the valve after a delay, and only during that time, the pressure oil on the outlet side of the hydraulic actuator is communicated with the inlet side. was. Furthermore, for example, special public service 61-2
As shown in the '8532 publication, there was a pair of bypass valves each including a sleeve, a poppet in the sleeve, and a spool in the poppet.

0004

[Problems to be Solved by the Invention] However, in the conventional products as described above, for example, the one shown in Japanese Unexamined Patent Publication No. 57-25570 has a problem in that the contact surface between the movable seat and the poppet is connected to the import side of the hydraulic actuator. Since it was connected to the port side, there was a large amount of internal leakage, and the valve opened with a delay due to being pushed by the spring, resulting in uncertain operation. Furthermore, for example,
The device shown in Publication No. 2 has a very complicated structure because the bypass flow rate is controlled by a poppet, and has problems such as large external dimensions due to processing technology. The object of the present invention is to solve the problems of conventional products, to completely prevent reversal operation immediately after the hydraulic actuator is stopped, to have no internal leakage, to ensure reliable operation, and to have an extremely simple structure. The object of the present invention is to provide a reversal prevention valve whose external dimensions can be reduced in terms of processing technology.

[0005]

[Means for Solving the Problems] Therefore, the present invention has solved the above-mentioned problems of the conventional products by providing a reversal prevention valve as set forth in the claims.

[0006]

Embodiments Next, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a sectional view showing a reversal prevention valve according to an embodiment of the present invention. Viewed from the hydraulic circuit in which the embodiment anti-reversal valve of the present invention shown in FIG. 3 is used, the embodiment anti-reverse valve 32 of the present invention is
The valve body 1 has an inlet 21 communicating with an inlet 38 of a hydraulic actuator 33 and an out port 22 communicating with an outlet 39, and is disposed in communication with the inlet 38 and outlet 39 of the hydraulic actuator 33. The spool 2 is slidably inserted into the valve body hole 40 of the anti-reversal valve 32, and the spool 2 is pressed from both sides by a pair of springs 9, 10, and has an import 21, an out port 22, and a throttle 13, 14 on each side. A spring oil chamber 23.24 is provided which communicates with a pilot passage 26.27. The spool 2 has a blind stepped hole 41 in the middle, and its large diameter hole 43 connects to the first radiation hole 19 that communicates with the import 21 when inactive, and its small diameter hole 17 connects to the spring oil chamber 23 that communicates with the import 21 when the spool 2 is inactive. Out port 22 only when pressure oil is introduced
The large diameter hole 43 has a blind step hole 41 with a second radiation hole 18 in communication with the first radiation hole 19 in the step part 45.
A check valve 3 is provided to check the flow from the to the second radiation hole 18.

[0007] In the embodiment, the spool 2 is
The guide 5.6 in contact with the spring 9.10 and the sleeve body 47 in which each radiation hole 19.18 is provided are separate bodies. Furthermore, each spring 9.10 is made adjustable in stroke by means of a stop plug 7.8. 15.16 is the step part of the valve body hole 40 and the stopper plug 7
．． The stroke of the spool 2 is determined by the ring that moves between the step part and the inside of the stopper plug 7.8.

Furthermore, in the embodiment, the hydraulic actuator 3
3, the spool 2 has a pair of blind stepped holes 41 and 42, a second large diameter hole 44 adjacent to the small diameter hole 17, and an inoperable second large diameter hole 44. A third radiating hole 20 communicating with the out port 22 is added, and a second check valve is provided at a step 46 in the second large diameter hole 44 to check the flow from the third radiating hole 20 to the second radiating hole 18. 4 is provided.

In operation, when the switching valve 36 is switched to the left position and the hydraulic actuator 33 is rotating, the anti-reversal valve 32 is in the state shown in FIG. Pressure oil is introduced through a pilot passage 27 with a throttle 13, the spool 2 is located at the right position in the figure, and the second radiation hole 18 is located at the out port 2.
2 can be communicated with. When the switching valve 36 is switched to the neutral position shown in FIG. 3 in order to stop the hydraulic actuator 33 while it is rotating, the hydraulic actuator 33 does not stop immediately and tries to continue rotating due to the inertia of a driven body (not shown). . However, since both the inlet 38 and the outlet 39 of the hydraulic actuator 33 are already closed when the switching valve 36 is in the neutral position, the hydraulic pressure on the inlet 38 side increases. It flows to the hydraulic actuator outlet 39 through the brake valve 35, which is a relief valve, and acts as a brake operation by the brake valve 35 on the hydraulic actuator 33.

At this time, after the brake is applied for a certain period of time, the hydraulic actuator and the driven body stop, but due to the inertia of the driven body, high pressure is generated on the outlet side of the hydraulic actuator due to the pumping action of the hydraulic actuator, and vice versa. The pressure at the inlet 38 of the hydraulic actuator 33 drops rapidly. The high pressure oil on the outlet side of the hydraulic actuator passes through a pilot passage 26 with a throttle 14 communicating with the out port 22, is guided to the spring oil chamber 24, pushes the spool 2 together with the spring 10, and returns to the neutral position shown in FIG. At this time, the flow rate of the pressure oil flowing from the spring oil chamber 23 to the import 21 is controlled by the throttle 13, and the return time of the spool 2 is controlled.

Immediately before the high-pressure oil on the outlet side of the hydraulic actuator communicates with the outport 22, the spool 2 is in the right position as shown in FIG. 2, and the second radiation hole 18 is in communication with the outport 22. While the spool 2 returns to the neutral position shown in FIG. Therefore, the high-pressure oil generated on the outlet side of the hydraulic actuator immediately after stopping due to the pumping action of the hydraulic actuator due to the inertia of the driven body escapes to the import 21 and is transferred to the hydraulic actuator 33.
prevent reversal. When the switching valve 36 is switched to the right position and the hydraulic actuator 33 is rotating in the opposite direction, when stopping the hydraulic actuator 33, the import 21 is similarly moved while the spool 2 returns to the neutral position shown in FIG.
The high-pressure oil opens the check valve 4 and escapes to the outport 22. Therefore, the high-pressure oil generated on the hydraulic actuator outlet side immediately after the stop due to the pumping action of the hydraulic actuator escapes to the outport 22 and the hydraulic actuator 3.
Prevent the reversal of 3.

0012

[Effects of the Invention] As explained above, according to the present invention,
The spool includes a valve body and a spool slidably inserted into the valve body hole, the spool having a blind step hole in the middle part, and a large diameter hole having a first radial hole to a second radial hole in the step part. A check valve is provided to reverse the flow to the hole, and when stopping the hydraulic actuator while it is rotating, the high pressure oil at the out port is checked while the spool returns to the neutral position shown in Figure 1. The valve is opened and the oil flows out to the out port, and as a result, the high-pressure oil generated at the outlet side of the hydraulic actuator immediately after the stop due to the pumping action of the hydraulic actuator escapes to the out port and becomes a reversal prevention valve that prevents the hydraulic actuator from reversing. In this way, the present invention controls the bypass flow rate using the spool, and the spool switching speed is controlled by the throttle of the pilot passage, and does not use a spring or a poppet with large leakage, so when the hydraulic actuator is stopped, it can be stopped. It is now possible to provide a reversal prevention valve that completely prevents immediate reversal operation, has no internal leakage, is reliable in operation, has an extremely simple structure, and can be reduced in external dimensions due to processing technology.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the anti-reversal valve of the present invention.

FIG. 2 is a sectional view showing the state of the anti-return valve in FIG. 1 when it is in operation.

FIG. 3 is a hydraulic circuit diagram showing a state in which the anti-reversal valve of FIG. 1 is used.

[Explanation of symbols]

1 Valve body 2 Spool 3 Check valve 4 Second check valve 5.6 Guide 7.8 Stopper plug 9.10 spring 13.14 aperture 17 Small diameter hole 18.19.20 Radiation hole 21 Import 22 Outport 23.24 Spring chamber 26.27 Pilot passage 32　　　　　　Reverse prevention valve 33 Hydraulic actuator 40 Valve body hole 41.42 Blind step hole 43.44 large diameter hole 47 Sleeve body

Claims (3)

[Claims] Claim 1: A valve body of a hydraulic actuator, having an in port communicating with an inlet and an out port communicating with an outlet; a spool provided with a spring oil chamber that communicates with the port through a pilot passage with a throttle, the spool having a blind stepped hole in the middle, and a large diameter hole that communicates with the import when inactive. , the small diameter hole has a blind stepped hole in which a second radial hole is bored, which communicates with the out port only when the spool is introduced into the spring oil chamber communicating with the import, and the large diameter hole is a reversing check valve characterized in that a check valve is provided in the stepped portion to check the flow from the first radiating hole to the second radiating hole. 2. The spool has a guide in contact with the spring and a sleeve body provided with each of the radial holes, and each of the springs has a stroke adjustable by a stopper plug. Reversing check valve according to 1. 3. The spool has a pair of blind stepped holes, a second large diameter hole adjacent to the small diameter hole, and a second large diameter hole adjacent to the small diameter hole.
A third radiating hole is added to the large diameter hole that communicates with the out port when not in operation, and a second check is provided at the step part of the second large diameter hole to reverse the flow from the third radiating hole to the second radiating hole. The reversing check valve according to claim 2, further comprising a valve.