| 摘要 |
PURPOSE:To enable to eliminate variation of the force acted to vanes by pressure in back-pressure chambers, by forming a pressure-change compensating chamber having a volume at least twice as large as the maximum total volume of the back-pressure chambers in the manner that it is communicated to the back-pressure chambers, and thereby absorbing change in the total volume of the back-pressure chambers. CONSTITUTION:Since vanes 4 are moved in respective slots 3 formed in a rotor 3 along the inner surface 6a of a cylinder 6, the volumes of back-pressure chambers 18 are changed with movement of the vanes 4. According to the present invention, however, there is provided a pressure-change compensating chamber 23 having a volume at least twice as large as the maximum total volume of the back-pressure chambers 18, in the manner that the chamber 23 is communicated to the back-pressure chambers 18. Therefore, the volume change of a space 25 of the chamber 23 is relatively small as compared with that of the back-pressure chambers 18, and the volume change of the back- pressure chambers 18 is absorbed by the chamber 23, so that the pressure change in the space 25 itself is extremely small, and resultantly, the change of force acted to the vanes 4 can be rendered extremely small. Therefore, it is enabled to change the number of vanes irrespective of the configuration of the inner surface 6a of the cylinder 6. |
