Patent ID: 7985055
Filing Date: 2011-07-26
Classification: F04C

Abstract:
1. An oil pump mounted on a rotation shaft rotating with a crankshaft of an engine, the oil pump comprising: an inner rotor fixed to the rotation shaft; and an outer rotor that rotates with the inner rotor, wherein at least one rotor of the inner and outer rotors has a mass center formed apart from a rotation center of the corresponding inner and outer rotors; wherein a rotation center of the outer rotor is formed apart from a rotation center of the inner rotor and the outer rotor and the inner rotor are coupled by a plurality of vanes; wherein the outer rotor is provided with a balance weight such that a mass center of the outer rotor is formed apart from the rotation center of the outer rotor; wherein the inner rotor is provided with a balance weight such that a mass center of the inner rotor is formed apart from the rotation center of the inner rotor; wherein the balance weight of the inner rotor is substantially between the balance weight of the outer rotor and the rotation center of the inner rotor.