| 摘要 |
PURPOSE:To decrease mechanical loss between the point end of a vane and the internal surface of a cam ring, by forming a back pressure chamber in the base end part of the vane to selectively communicate with high and low pressure regions bordering a predetermined rotary speed thus holding a surface pressure in the point end of the vane to a fixed value. CONSTITUTION:A housing groove 27, communicating with a back pressure chamber formed in the base end part of a vane, is formed in the side surface of a rotor 11, and a ball 27 is contained in said housing groove 27. A plate 32, being arranged in a cut part 30 of a front side block 9 facing to the housing groove 27, is adapted to the ball 28 by urging force of a spring 31. If a speed of the rotor 11 increases, the ball 28, pressing by centrifugal force the plate 32 to a side of the front side block 9 against the urging force of the spring 31, causes the plate 32 to block an opening part 34b of a high pressure communication path 34. In this way, a pressure in the back pressure chamber 18, gradually decreasing by a leak, causes a surface pressure in the point end of a vane 17 to decrease. |
