Importance

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Abstract

Two rotary shafts to transfer a motive power are relatively rotatably coupled. One of the shafts is coupled to a rotor and the other is coupled to a cam. A plurality of plungers which execute a stroke motion in the axial direction by the relative rotation with the cam are provided for the rotor. The oil injection and discharge into/from the plunger enclosing chamber are executed by a rotary valve. The rotary valve automatically switches a phase relation so as to obtain correct opening/closing timings even if the direction of the relative rotation changed. The rotary valve rotates integratedly with the cam side and opens or closes intake/discharge holes of the plungers for a plurality of intake ports and discharge ports which are alternately formed on the cam surface. The discharge ports on the front surface of the rotary valve are mutually coupled by communicating grooves formed on the back surface. An orifice is formed between the communicating groove and the intake port. A force by hydraulic reaction forces of the front and back surfaces of the rotary valve is set to be smaller than a force by a plunger liquid pressure acting area which is applied to the rotary valve. Thus, a force such as to always closely adhere a gap between the rotor and the rotary valve is generated, thereby minimizing an oil leakage from the rotary valve.

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First Claim