| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of cavitation by arranging a delivery port so as to become larger than pressure applied to an outer peripheral surface of an outer rotor by delivery pressure, and setting a closing-in central position of a suction port on a straight line connecting points of moving both rotors to the suction port side by radial directional play quantity. SOLUTION: A suction port 5 and a delivery port 6 are bored in a bottom surface of a housing hole 4A of a housing 4, the delivery port 6 becomes larger than an outer peripheral diameter of an outer rotor 3, and delivery pressure applied to an outer peripheral surface of the outer rotor 3 becomes larger than delivery pressure applied to an inner peripheral surface of the outer rotor 3 so that a delivery port 6 side outer peripheral surface of the outer rotor 3 receives the delivery pressure. A central position R of a closing-in part 9 is set on a straight line L connecting a point C2' moved to the suction port 5 side by radial directional play quantity A of an inner rotor 2 and a point C1' of moving the outer rotor 3 to the suction port 5 side by radial directional play quantity B. Cavitation of an oil chamber is prevented in a whole rotating speed area.
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