JPS57116912A - Composite valve - Google Patents

Abstract

PURPOSE: To make it possible to control the operating speed of an actuator in a composite valve including a directional control valve and a pressure compensating valve, by providing such an arrangement that fluid pressure applied to the pressure compensating valve is adjusted, depending upon the operating direction of the actuator connected to the directional control valve.

CONSTITUTION: An annular groove 41a is, at first, communicated with a load passage 20a and then a load passage 20b is communicated with a discharge passage 24, when a spool 25 in a directional control valve 2 is moved to, for example, the right, so that fluid pressure corresponding to a load acting to a cylinder 1 is applied into a spring chamber 53 of a pressure compensating valve 4 through passages 20a, 40. Therefore, a valve member 51 in the pressure compensating valve 4 is moved to the left due to the pulling force of a load pressure spring 54 in the spring chamber 53, thereby fluid flow between annular passages 42, 44 restricted. As the result, the discharge pressure of a pressure fluid source 3 is increased to a value corresponding to the restriction between the annular passages 42, 44. The cylinder 11 moves a piston rod 11 to the right when a groove 38a communicates a bridge passage 23 with a load passage 20a due to the movement of a spool 25 to the right.

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