Rotor structure of inscribed gear pump

An inscribed gear pump comprising:

• a housing forming a cylindrical space;
• a driven rotor rotatably arranged in the cylindrical space and including a plurality of inner gears;
• a driving rotor rotatably arranged in the driven rotor and including a plurality of outer gears engaging with the respective inner gears;
• a plurality of interspaces formed between the inner gears of the driven rotor and the outer gears of the driving rotor respectively, a volume of each of the interspaces being increased and decreased so as to complete one cycle in a rotation for the purposes of performing an intake and a discharge of fluid;
• an inlet port being in communication with the cylindrical space;
• an outlet port being in communication with the cylindrical space;
• and
• a groove formed on a side face of the driving rotor and being in communication with the inlet port and the at least one of the interspaces;
• the groove extending toward a gear bottom portion formed between the adjacent outer gears in a radial direction of the driving rotor.