Internal gear pump motor

An internal gear pump motor comprising:

• a housing;
• a pinion rotatably supported in said housing;
• an internal gear rotatably supported in said housing and meshing with said pinion in said housing;
• and filler piece means located in a space defined between said pinion and said internal gear for dividing the space into two regions which provide a low pressure region and a high pressure region during operation;
• wherein:
• said filler piece means includes at least one filler piece floatingly mounted within said space and having portions capable of coming into sliding engagement with tooth crests of said pinion and tooth crests of said internal gear respectively in a portion of said space where the distance between the tooth crests of the pinion and the tooth crests of the internal gear is reduced toward said low pressure region;
• and
• said internal gear pump motor further comprises a stopper pin secured to said housing operative to engage one end of said filler piece on the side of said low pressure region for restricting the circumferential movement of the filler piece toward the low pressure region, and spring means associated with said housing for urging said filler piece toward said low pressure region.