Scavenge pump with improved lubrication

A scavenge pump, comprising:

• a pump housing including a housing body and a cover member, the housing body having a rotor chamber in which an inlet port, an outlet port, and a bearing hole formed by shaft holes with varying diameters with a stepped surface therebetween are provided;
• an outer rotor housed in the rotor chamber and having inner teeth;
• an inner rotor having outer teeth and a shaft support hole;
• and
• a drive shaft inserted or fixedly attached to the shaft support hole of the inner rotor, wherein
• the bearing hole includes a stepped inner circumferential part having a larger diameter than that of the drive shaft at an open peripheral edge on one side facing the rotor chamber, and a groove that extends between a point close to a trailing end of the outlet port and the stepped inner circumferential part is formed, and
• wherein the inner rotor includes a cylindrical part that surrounds the shaft support hole, the cylindrical shaft part being fitted in or axially supported by the stepped inner circumferential part.