JPS608504A - Valve - 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 the Invention The present invention relates to a valve that automatically supplies fluid flow from a fluid supply alternately to opposite sides of a double-acting hydraulic actuator for reciprocating motion.

This type of valve is useful, for example, in hydraulic garage cleaners, bilge pumps, some types of pipe benders, and the like.

Prior Art and Problems Conventional techniques for achieving this automatic reciprocation use electrical devices such as electrically actuated solenoid valves and are unreliable.

or used significantly more complex hydraulically operated valves.

SUMMARY OF THE INVENTION A valve assembly having a valve spool within a valve body according to the present invention is provided in which the position of the valve spool controls the flow of pressurized fluid to one or the other of a double-acting hydraulic actuator. , a spring-operated valve device for controlling fluid flow from a passage downstream of the valve spool to the pilot spool, which opens when the pressure in the passage exceeds a predetermined value to move the valve spool back against the force of the spring; The valve spool is switched to initiate a return stroke of the actuator, and the valve spool is held in the switched position against a return spring by back pressure acting on the return stroke valve spool of the hydraulic actuator.

Back pressure is created by a restriction that throttles fluid flow from the actuator on the return stroke. When the actuator reaches the end of its return stroke or is stopped by some other resistance, the back pressure is reduced and the valve spool is switched to the initial position by the return spring. This cycle repeats until the pump stops.

The spring-actuated valve system is set to move the pad spool at a pressure slightly lower than the set pressure of the system relief valve. If the actuator reaches an end position or is stopped by some other resistance, passage pressure increases and the valve arrangement opens to actuate the pilot spool. This pilot passage branches off from the passage to one side of the actuator. The actuator is typically a hydraulically actuated cylinder-piston assembly.

Operation The valve device according to the present invention does not require any other power, has a simple structure, and automatically switches to reciprocate the double-acting piston.

Embodiments Examples and drawings illustrating the present invention will be described.

Figures 1-4 show a control device for a hydraulic actuator according to the invention, showing a double-acting cylinder-piston assembly 20, 21 as an example of an actuator. A pump 1 that supplies the pressurized original to the actuator and a return passage 3 that returns it to the reservoir 4
and has. The relief valve 2 controls the maximum pressure supplied by the pump.

A valve assembly according to the invention controls fluid flow from a pump to an actuator. The valve assembly includes a valve body 11 and a valve spool that slides within the valve body.

The valve spool 12 is pushed by a return spring 13 to the right end in the example shown, and is connected to the pressure sources, namely the four springs 1 and the cylinder 2.
It communicates with chamber A of 0. At this position, the cylinder 200 chamber B communicates with the return passage 3.

The outlet of the valve body and chambers A and B are connected by two passages 16. A check valve connected to chamber A via a branch passage 23 from passage 16 has a ball 17 pressed against the valve seat by a spring 25'. This check valve is set to open with a pressure slightly lower than the pressure between the relief valve 2. A pilot spool 14 is cooperable between the passage 23 and the right end of the valve spool 12.

FIG. 1 shows the starting position of the valve spool 12, in which the pressurized fluid from the pump 1 is guided into the chamber A and the piston rod 21.
Push to the left. When the piston rod 21 reaches the end position shown in FIG. 2, the piston rod does not move, so the pressure in the chamber A rises, and when the pressure reaches the level that opens the check valve, the ball 17 resists the spring 25 and pushes against the valve seat. , the pressurized fluid passes through passage n and acts on one end of pilot spool 14 . Therefore, the spool 12 moves to the left against the force of the return spring 13.
The position of the valve spool is switched so that pressurized fluid from the pump is introduced into chamber B and chamber A communicates with return passage 3, as shown in FIG. Piston rod 21 thus begins its return stroke.

During the return stroke, pressurized fluid is discharged from chamber A by piston 21 and returned to reservoir 4.

A restriction D for a passage returning to the reservoir is formed between the end faces of the pilot spool 14 and the valve spool 12. Valve spool 1
2 and returns to the reservoir from chamber A. The valve spool 12 is forced in the direction of the return spring 13 by the back pressure created by the restriction D provided in the return fluid path. Thus, as long as the back pressure acting on the valve spool is greater than the force of the spring 13, the valve spool 12 remains in the switched position of FIG.

A radial hole 28 formed in the valve spool 12 provides a relief passage for the pressure trapped in the end chamber 27 of the spool 12 during the return movement. This hole is dimensioned so that the pressure drop through hole 28 is significantly greater than the pressure required to maintain spool 12 in the leftmost position against spring 13.

The pilot spool 14 has a flange or circlip 15 in contact with the valve body at the right end position shown in FIG. After the check valve ball 17 closes the passage 23, fluid within the passage 23 only leaks along the outer surface of the spool 14. Thus, the return speed of the pilot spool is determined by the selection of the leak path C.

At the end of the return stroke of the piston rod 21, when the fluid has been discharged from the chamber A and the back pressure in the chamber 27 passage has decreased, the return spring 13 pushes the spool 12 to the right, switching the position of the valve spool. the position shown in FIG. 1 and the cycle repeats automatically. Valve spool is pilot spool 1
4 and return the spool 14 to the right end position. Passage 23
The fluid in the passage 23 during the return stroke of the spool 14
extruded inward.

The cycle repeats continuously and continues until the supply of pressurized fluid is terminated. When the pump stops, the valve is automatically reset by spring 3 to the position shown in FIG.

If excessive resistance occurs during actuation of the actuator, the valve will automatically switch and reverse stroke. The cycle continues without stopping. That is, due to the resistance, the pressure in chamber A increases and triggers the valve arrangement, or the stoppage of piston rod movement causes the valve to switch due to the absence of back pressure.

Effects of the Invention The present invention is a valve device that automatically directs fluid flow from a pressurized fluid source to both sides of a double-acting, hydraulic actuator alternately,
No other actuating device is required to switch the operation of the valve spool of the valve device, and the rise and fall in pressure accompanying the stoppage of the actuator is used as the actuation source. That is, the valve spool is returned to one end position by the spring and the stroke of the actuator is started, and the increase in internal pressure at the stroke end leads pressure from the actuated valve to the pilot spool to switch the valve spool. At the end of the return stroke, the valve spool end backpressure decreases and the valve spool returns to its original position, performing an automatic cycle.

[Brief explanation of the drawing]

1 to 4 are diagrams showing respective operating positions of the valve device of the present invention that allows automatic reciprocation of a hydraulic actuator. l Bump 2 Relief valve 4 Reservoir 11 Valve Main body 12 Valve spool 13.25 Return spring 14 Pilot spool 17 Ball 20 Cylinder 21 Piston rod 23 Branch passage A, E Chamber C, D Gap

Claims (1)

Claims: 1. A valve assembly having a valve spool (12) within a valve body (11), wherein the position of the valve spool directs the flow of pressurized fluid to one or the other of a double-acting hydraulic actuator. a spring actuated valve arrangement (14) for controlling fluid flow from a passage downstream of the valve spool to the pilot spool (14);
17; 25), which opens when the pressure inside the passage exceeds a predetermined value and moves the valve spool (12) against the force of the return spring (13) to switch the valve spool and start the return stroke of the actuator. Valve characterized in that the valve spool (12) is held in the switching position against a return spring by a back pressure acting on the return stroke valve spool of the hydraulic actuator. 2. The spring-operated valve device includes a ball (17), a valve seat, and a spring (25) and is accommodated in the valve body, and the ball contacts the valve seat by the spring. valve. 3. The pilot spool (14) is slidable in a hole in the valve body, the hole opening into a chamber of the valve body accommodating the valve spool (12). valve. 4. The valve according to claim 3, wherein a leakage path (C) is formed between the pilot spool (14) and the hole, and the leakage path controls the return movement of the pilot spool to its initial position. . 5. The valve according to claim 4, wherein the initial flame position of the pilot spool (14) is determined by a collar (15) formed on the pilot spool (14). 6. A valve according to one of claims 1 to 5, in which the back pressure is created by a restriction (2) which throttles the fluid flow returning from the actuator on the return stroke. 7. The return flow flows through an orifice or chamber (27) of the valve spool (12), and the restriction (D) flows through the orifice (27).
) at the downstream end of the pilot spool 04) and the valve spool (
12) The valve according to claim 6, which is formed between opposing end faces of the valve. 8. the orifice (27) in the valve spool (12);
8. A valve as claimed in claim 7, including one or more holes (28) communicating with the orifice to relieve pressure trapped in the orifice to the valve spool chamber during the return stroke.