Patent ID: 7117889

Claim:
A three-way valve for switching between a first state in which fluid is caused to flow from a high-pressure port to a medium-pressure port, and a second state in which the fluid is caused to flow from the medium-pressure port to a low-pressure port, the three-way valve comprising: a first main valve including a first valve element disposed such that the first valve element can move to and away from a first valve seat formed in a passage between the high-pressure port and the medium-pressure port, on an upstream side thereof, a first piston having a first pressure chamber into which the fluid is introduced from the high-pressure port via an orifice, on a side of the first piston opposite to a side thereof where the first piston is coupled to the first valve element, a first spring urges the first valve element in a valve-closing direction; a second main valve including a second valve element disposed such that the second valve element can move to and away from a second valve seat formed in a passage between the medium-pressure port and the low-pressure port, on an upstream side thereof, a second piston having a second pressure chamber communicating with the first pressure chamber, on a side of the second piston opposite to a side thereof where the second valve element is in abutment therewith via a valve hole of the second valve seat, and a second spring urging the second valve element in a valve-closing direction; and a pilot valve for controlling a pressure passage formed in a body accommodating the first and second main valves, for communication between the first pressure chamber and the medium-pressure port, by a solenoid force thereof, such that the communication is established or blocked.