Solenoid valve

Abstract

In a solenoid valve, an annular oil grooveis formed at a portion corresponding to a spring chamberon the external surface of a sleeve, a drain passageis formed to make an upper part of the annular oil groovecommunicate with the outside of an insertion bore, and a throttle holeis provided at a lower part of the annular oil groovefor making the annular oil groovecommunicate with the spring chamber. Since the annular oil groovecommunicates with the outside of the insertion boreat its upper part through the drain passage, it can be realized to store the operating oil to the height of the upper part of the annular oil groove, so that the operating oil can be reserved in the spring chamberwhich communicates with the annular oil groove through the throttle hole. Further, the operating oil is supplied from a feedback portnext to the spring chamberthrough a clearance between the spool valveand a valve hole. Thus, the solenoid valveis able to secure the damping effect of the working oil on the spool valveand a plungerand to suppress the self oscillation even while being operated in the atmosphere for a long time.