| 摘要 |
In each of both ends of a land portion provided between channels which are formed in a slidable contact surface of a rotor assembled in a sleeve so as to be rotationally displaceable relative to the sleeve and thus control connection and disconnection of fluid paths, a chamfer is formed from an edge to a throttling action end portion of the land portion of the rotor so as to have at least one flat acting surface and a curved acting surface continuously connected to the flat acting surface. The curved acting surface of the chamfer is formed to have a smooth, continuously curved surface with a radius of curvature which decreases gradually from a connection portion with respect to the flat acting surface to a point at which it is connected to an outer diameter portion of the rotor. When a throttling action is performed by rotationally displacing the rotor with respect to the sleeve, an angle defined between the flat and curved acting surfaces at a connection point between them and an angle defined between the curved acting surface and a tangent at a point at which the curved acting surface is connected to the outer diameter portion of the rotor are maintained small, which reduces fluid noise caused by cavitation.
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