Patent ID: 9581156
Date: 2017-02-28
CPC Classifications: F04C

Claim:
1. A gear pump including an inner rotor that has a plurality of external teeth and that is driven to rotate, an outer rotor that has a plurality of internal teeth, that is placed so as to be offset with respect to the inner rotor, and that rotates together with the inner rotor with a part of the plurality of internal teeth meshing with a part of the plurality of external teeth, a suction port that communicates with such an inter-tooth chamber that increases in capacity with rotation of the inner rotor and the outer rotor out of a plurality of inter-tooth chambers defined by the external teeth and the internal teeth, and a discharge port that communicates with such an inter-tooth chamber that reduces in capacity with rotation of the inner rotor and the outer rotor out of the plurality of inter-tooth chambers, wherein an outer inner wall surface of the suction port which is located on a downstream side in a rotor rotation direction is located inward of a bottom land between the internal teeth, and the suction port has a shallow portion extended inward from the outer inner wall surface on the downstream side in the rotor rotation direction, and a deep portion that is formed so as to be continuous with the shallow portion and that is deeper than the shallow portion, and the outer inner wall surface that is located upstream, in the rotor rotation direction, of a closing portion of the suction port where communication with the inter-tooth chamber is cut off is located inward of the bottom land between the internal teeth that define the inter-tooth chamber whose communication with the suction port is about to cut off.