Patent ID: 6378557
Filing Date: 2002-04-30
Classification: F16H,G05D,Y10T

Abstract:
A pressure regulation valve for a hydraulic circuit having a supply pressure source and a drain, comprising:a housing having an input port to communicate with the supply pressure source, an output port to communicate with the hydraulic circuit and at least a drain port to communicate with the drain; a pilot pressure producing member supplying pilot pressure, which increases from zero to a value exceeding a given value, to the housing; a pipe shaped first spool accommodated slidably in the housing so as to receive the pilot pressure, the first spool being moved therein by first thrust force due to the pilot pressure so that the output port communicates internally with the drain port, when the pilot pressure is substantially zero, and communicates internally with the input port, when the pilot pressure exceeds the given value; a first biasing member giving the first spool a biasing force acting in an opposite direction to receiving the pilot pressure; a feedback hydraulic chamber provided in the housing; a second spool accommodated slidably inside the first spool so as to receive the pilot pressure, the second spool being movable therein by second thrust force due to the pilot pressure so that the feedback hydraulic chamber communicates internally with the output port, when the pilot pressure is below the given value, and communicates internally with the drain port, when the pilot pressure exceeds the given value; and a second biasing member giving the second spool second biasing force acting in an opposite direction to receiving the pilot pressure, wherein the feedback hydraulic chamber gives the first spool feedback force acting in an opposite direction to which the first spool receives the pilot pressure when the feedback hydraulic chamber communicates with the output port.