Hitachi, Ltd.

Hitachi Automotive Engineering Co., Ltd.

Tadao Uchida

Tomoo Ito

Yutaka Fujitsugu

A hydraulic control solenoid valve comprising a plunger provided in a coil case and a shaft freely shiftable in a body. The shaft is provided with a first spool valve and a second spool valve. A feedback chamber is provided in the body and on the side of the first spool valve. A round shaped thin plate is fixed to the end of the first spool valve and positioned in the feedback chamber so as to form a constricted part of a flow passage formed between an interior wall of the feedback chamber and a peripheral surface of the thin plate. The cross-sectional area (S.sub.2) of the constricted part is not greater than 0.04 of the side surface area (S.sub.1) of the thin plate. The thin plate adds the damping coefficient (C.sub.d) and also functions as the stabilization of the behavior of the spool valves. The thin plate facilitates the prevention of the resonance phenomenon of the spool valves.

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Yamagata, Japan

Tadao Uchida