| 摘要 |
PROBLEM TO BE SOLVED: To prevent the deterioration of pumping efficiency and suppress abrupt pressure fluctuation in a pump chamber. SOLUTION: A drive gear 12 and a driven gear 13 are stored in a pump chamber composed of a first housing and a second housing. Capacity parts 131 to 140 thereof are opened to a discharge port 26 formed at least one of the first and second housings to form discharge capacity parts 30, while they are opened to a suction port 27 to form suction capacity parts 31. A maximum capacity part 136 is formed between the suction capacity part 31 and the discharge capacity part 30. A recession 33 having an elastic member 38 which promotes communication between the discharge port 30 and the maximum capacity part 136 in proportion to discharge pressure is formed on an end wall 32 of the discharge port 30 at its rear side in a rotational direction. Alternatively, a projection 35 of elastic material which retards the communication between the suction port 31 and the maximum capacity part 136 according to the suction pressure is formed on an end wall 34 of the suction port 31 at its front side in a rotational direction.
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