JPH0121261Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solenoid-controlled directional switching valve that improves the ability to switch the oil flow direction by using a solenoid to switch the spool.

In general, a solenoid-controlled directional control valve has a solenoid on one or both sides of the spool, and by energizing the solenoid, the spool is pushed out via a push pin to switch the oil path. shows the hydraulic diagram display signal and structure of a spring center type solenoid controlled directional valve. It has solenoids 1 and 1' on both sides, and in the figure, both solenoids are in a demagnetized state, and the spool 2 is positioned neutrally as in the state shown in Figure 1b by the spring force of springs 3 and 3'. By energizing one solenoid 1 or 1', the suction force of the solenoid pushes the spool 2 through the push pin 4 or 4', thereby switching the oil flow to the opposite side. Then solenoid 1 or 1'
When the spool 2 is demagnetized, the springs 3, 3'
It returns to its original neutral position with the force of. Now, one of the solenoids, for example 1', is energized and the spool 2 slides to the left via the push pin 4', and oil flows from the P port to the A port, and this A
It is supplied to the load (not shown) from the port, flows back to the B port, further flows to the spring chamber 5', passes through the bypass pipe 7 provided in the body 6, and is supplied to the tank (not shown) from the tank port T. Return to When oil flows along such a path, a pressure difference ΔP (a pressure difference generated at both ends of the bypass pipe 7) is generated between the spring chambers 5 and 5'. Therefore, this pressure difference △
The pressure in the spring chambers 5 and 5' created by P acts on the spool ends, respectively. The pressure acting on the spool end becomes a thrust that moves the spool and acts in the opposite direction to the direction of action of the spring force, significantly reducing the switching ability of the solenoid-controlled directional switching valve. Furthermore, as the flow rate passing through the load increases, the differential pressure △P increases, and when the force acting on the spool end surface increases and becomes almost equal to the spring force, the spool will not return and it will become impossible to switch the oil flow direction. There is. This kind of oil flow path is
As shown in Figure 2, the dimensions of the mounting surface of a solenoid-controlled directional control valve are specified by the International Organization for Standardization (ISO) standards, and the positions of the ports P, T, A, and B are determined by the mounting mount. Therefore, the above-mentioned path has to be followed, and a differential pressure △P is generated which reduces the switching ability. In order to reduce this differential pressure as much as possible, it is possible to increase the passage area of the bypass pipe line 7, but this bypass line 7 is cast or machined into the body 6, and the line Enlarging the area sufficiently would not only reduce the thickness of the body, which would pose a problem in terms of pressure resistance, but it would also be impossible to make the external dimensions larger than necessary because of the restrictions on the dimensions of the mounting surface. .

This invention was made to solve the above-mentioned problems, and includes a conduit that penetrates both end faces of the spool, and a spring chamber that intersects the conduit at right angles and is provided at both ends of the spool. It is an object of the present invention to provide a solenoid-controlled directional switching valve that is provided with separate pipe lines that communicate with each other, and that reduces the pressure difference acting on both end faces of the valve and improves its switching ability.

Next, the present invention will be described with reference to an illustrated embodiment. FIG. 3a shows a front view of the spool according to the invention, and FIG. 3b shows a central longitudinal sectional view. Reference numeral 10 denotes a spool with a conduit 12 extending in the axial direction between both end surfaces 11 and 11', and further conduits 13 and 1 intersecting this conduit 12 at right angles near both end surfaces.
3' is passed through.

Figures 4a and 4b show the hydraulic diagram symbol and its structure for a solenoid-controlled directional valve using a spool as described above, and the configuration corresponds to the components shown in Figures 1b and 3b. The same numbers are given to the components. That is, the solenoid-controlled directional control valve shown in FIG. 4b has the same construction as the solenoid-controlled directional control valve shown in FIG. In the demagnetized state, the spool 10 is in a neutral position due to the spring force of the springs 3, 3'. Now, the solenoid 1' is energized, the spool 2 slides to the left via the push pin 4', oil flows from the P port to the A port, is supplied to the load, returns to the B port, and is sent to the body from the spring chamber 5'. The water passes through a bypass pipe 7 provided in the tank 6 and pipes 13', 12, and 13 provided in the spool 10 and passes between both end faces thereof, and is returned to a tank (not shown) from the tank port T. In this way, the flow path between the spring chambers 5 and 5' is connected to the bypass pipe 7 and the pipes 13', 12, 13.
Therefore, the difference in pressure acting on both end faces of the spool 10 is reduced. Moreover, since the conduit 12 provided within the spool 10 is the shortest flow path between the spring chambers 5 and 5', it is extremely effective in reducing the differential pressure.

As described above, according to the present invention, the difference in pressure acting on both end faces of the spool when switching the oil flow direction is reduced, and as a result, the switching ability of the solenoid-controlled directional control valve is improved, and the switching ability of the solenoid-controlled directional control valve is improved. Due to the direction of spring return like a valve, variation in switching speed can be minimized, and the switching flow rate can also be increased by more than 10L/min under the same conditions compared to conventional valves.

[Brief explanation of drawings]

Figures 1a and b are diagrams showing the hydraulic diagram and structure of a conventional spring center type solenoid-controlled directional valve, Figure 2 is a diagram showing the mounting surface of the solenoid-controlled directional valve, and Figures 3a and b are Figures 4a and 4b are diagrams showing a front view and a vertical cross-sectional view of the spool according to the present invention, and are structural diagrams showing an embodiment of the present invention using the spool. 1, 1'... Solenoid, 2... Spool, 4,
4'... Push pin, 5,5'... Spring chamber, 7... Bypass pipe, 10... Spool, 1
2...Pipe line, 13,13'...Pipe line.

Claims (1)

[Claim for Utility Model Registration] A bypass pipe is provided in the body to communicate between the spring chambers arranged at both ends of the spool, and a tank port is communicated with one of the spring chambers to switch the spool. Therefore, in a solenoid-controlled directional control valve that switches the direction of oil flow, the spool has a pipe line passing through between its both end faces, and a separate pipe line that intersects the pipe line at right angles and communicates with each of the spring chambers. A solenoid-controlled directional valve characterized in that it has a conduit.