Abstract: To provide an internal gear pump capable of preventing small vibrations due to pressure differences at the outlet port side of a crescent disposed between the outer rotor and the inner rotor, so that fatigue failure does not occur in the crescent over a long time period, whereby the durability can be increased. The internal gear pump includes a rotor unit, in which an inner rotor is disposed within an outer rotor on the inner peripheral side and a crescent is disposed in the gap between the inner rotor and the outer rotor, the rotor unit being housed in a pump casing. Outer cells are formed by the crescent and the outer rotor. Inner cells are formed by the crescent and the inner rotor. Linking of the outer cells and the outlet port, and linking of the inner cells 6 and the outlet port, start substantially simultaneously.

Abstract: To provide an internal gear pump capable of preventing small vibrations due to pressure differences at the outlet port side of a crescent disposed between the outer rotor and the inner rotor, so that fatigue failure does not occur in the crescent over a long time period, whereby the durability can be increased. The internal gear pump includes a rotor unit, in which an inner rotor is disposed within an outer rotor on the inner peripheral side and a crescent is disposed in the gap between the inner rotor and the outer rotor, the rotor unit being housed in a pump casing. Outer cells are formed by the crescent and the outer rotor. Inner cells are formed by the crescent and the inner rotor. Linking of the outer cells and the outlet port, and linking of the inner cells 6 and the outlet port, start substantially simultaneously.