Gear pump and manufacturing method of the same

A manufacturing method of a gear pump including an inner rotor configured to have a plurality of external teeth;

• an outer rotor configured to have a greater number of internal teeth than number of the external teeth of the inner rotor and arranged to be eccentric with respect to the inner rotor;
• a plurality of inter-teeth chambers, each being defined by two adjacent external teeth and two adjacent internal teeth;
• one intake port configured to communicate with the inter-teeth chamber of which volume increases with rotations of the inner rotor and the outer rotor;
• and a first discharge port and a second discharge port separated from each other by a partition wall to be independent of each other, each of the discharge ports being configured to communicate with the inter-teeth chamber of which volume decreases with the rotations of the inner rotor and the outer rotor, the manufacturing method of the gear pump comprising:
• forming the inner rotor such that an intake-side clearance is larger than a discharge-side clearance, where the intake-side clearance denotes a minimum value of a clearance between the external tooth and the internal tooth defining the inter-teeth chamber which communicates with the intake port and in which an amount of change in volume during rotation of the inner rotor by a unit angle is maximized, and the discharge-side clearance denotes a minimum value of a clearance between the external tooth and the internal tooth defining the inter-teeth chamber which at least partially overlaps with the partition wall between the first discharge port and the second discharge port when the amount of change in volume per unit angle is maximized.