| 摘要 |
PROBLEM TO BE SOLVED: To provide an oil pump capable of providing good oil flow rate in a wide rotation region without enlarging a structure. SOLUTION: A shape of a suction port 12 of the oil pump 1 is set so as to provide the best volume efficiency in an intermediate and high rotation region such as 4000 rpm, namely a rotation region where a request of the oil flow rate from an engine, a transmission, or the like is highest. A width, a diameter, and the like of each of rotors 15 and 16 are set relatively small enough to satisfy a request characteristic of oil flow rate in the rotation region. The suction port 12 is provided with a throttle valve mechanism part 30 for variably switching an effective cross section of the suction port 12. An ECU 45 controls the effective cross section of the suction port 12 so as to improve a volume efficiency of the oil pump 1 in each rotor rotation speed region via the throttle valve mechanism part 30.
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