Patent ID: 7435066

Claim:
An oil pump, comprising: an inner rotor; an outer rotor which rotates with the inner rotor while forming a cell; an intake port; a discharge port; a transfer side partition part formed between the terminal end of the intake port and the leading end of the discharge port; a side clearance established between the transfer side partitioned part and the rotor side surface of the inner rotor and the outer rotor; and a shallow groove which is formed only in the transfer side partition part, and which is communicated with the leading end of the discharge port but not communicated with the intake port, wherein an outer edge in a width direction of the shallow groove does not intersect with the cell on the transfer side partition part that is closed from the intake port and the discharge port, and is proximal to a circular locus the inner rotor gear bottom part configuring the cell, and is positioned toward the inside of the circular locus of the gear bottom parts of the inner rotor, wherein a side clearance is formed by bringing in proximity the shallow groove to the inner rotor gear bottom parts that configure the cell closed to the intake port and the discharge port on the transfer side partition part, while allowing communication between the shallow groove and the inner rotor near bottoms parts, and wherein fluid in the discharge port is transferred into the cell through the side clearance that allows communication established between the shallow groove and the inner rotor gear bottom parts.