Patent ID: 7866965

Claim:
A gear pump comprising: a pump housing formed with a gear receiving recess; annular inner and outer gears installed in the gear receiving recess and having respective tooth crest slopes that are in parallel to each other; a pump cover coupled with the pump housing for covering the gear receiving recess, the pump cover being formed with a passage whose inner end is exposed to an inner circular opening of the inner gear through a given part of the gear receiving recess, the given part being defined between a diametrically larger surface of the inner gear and an inner surface of the pump cover; and a hydraulic passage that includes the passage, the inner end, the given part of the gear receiving recess and the inner circular opening of the inner gear, wherein the inner and outer gears are meshed with each other such that the inner gear is biased in a direction to reduce thickness of said given part of the hydraulic passage when the inner gear is rotated while turning the outer gear therearound.