Patent ID: 8356620

Claim:
A pressure-controlled three-way valve device comprising: a valve body, an inlet circuit in said valve body, extended between an inlet port ( 17 A) and a second port ( 17 B), an outlet circuit ( 15 B) in said valve body, extended between said second port ( 17 B) and an outlet port ( 17 C); a plunger ( 21 ) housed in said inlet circuit and connected to a first urging means ( 23 ) that urges said plunger in a direction towards said inlet port ( 17 A), the plunger having a pair of seats comprising a pair of circumferential steps ( 41 A, 41 B) formed on the plunger outer wall surface; an o-ring ( 37 ) located between said steps and defining a pair of seals ( 39 A, 39 B); an outlet valve in said outlet circuit ( 15 B), said outlet valve comprising said pair of seals capable of alternatively abutting against said pair of steps upon moving of the plunger to at least three positions, a first position to communicate the inlet port with the outlet port, a second position to close communication between the outlet port, the second port and the inlet port, and a third position to communicate the outlet port with the second port, and a diaphragm ( 43 ) having a center part thereof sealably connected to the plunger and a periphery sealably retained in the valve body, whereby the diaphragm defines a seal between the plunger outer wall surface and the valve body at a position between the inlet port ( 17 A) and the second port ( 17 B), wherein the diaphragm naturally urges said plunger to rest at an intermediate position between the first and second positions.