| 摘要 |
PROBLEM TO BE SOLVED: To reduce the noise and vibration of a pump by smoothing the flow of a back pressure oil in back pressure grooves formed in a side plate and a cover plate. SOLUTION: This back pressure groove structure of a variable displacement vane pump comprises a rotor rotatably housed in a pump housing and having a plurality of vane grooves directed to the radial direction at peripherally equal spaces, and a cover plate having back pressure grooves communicated with the vans grooves. The back pressure groove in a side plate 5 is communicated with the high pressure side so that an annular back pressure groove is divided into divided back pressure grooves 28a, 28b on the pump suction side and on the pump discharge side, respectively, and the back pressure groove in the cover plate is formed as an annular back pressure groove or a C-type back pressure groove which is blocked at a single position where the annular back pressure groove is virtually partitioned on the pump suction side and on the pump discharge side.
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