Pump

A pump, comprising:

• a housing including a suction port, a discharge port, and an annular stator;
• a cylindrical outer rotor rotatably disposed at an inner peripheral side of the stator, including a plurality of permanent magnets arranged on an outer peripheral surface of the outer rotor to constitute a motor section in cooperation with the stator, and a plurality of plate holding grooves, each plate holding groove having a letter C shape in cross section, being extended in an axial direction of the outer rotor, and being formed on an inner peripheral surface of the outer rotor;
• an inner rotor disposed at a position eccentric with respect to the outer rotor, disposed at an inner peripheral side of the outer rotor, constituting a space communicated with the suction port and the discharge port against the outer rotor, and having an outer peripheral surface on which a plurality of slots are formed in a radial direction of the inner rotor;
• a drive shaft interlinked with the inner rotor and rotationally driven by means of a second drive source;
• and
• a plurality of linkage plates, each linkage plate having a head section of a circular cross section swingably fitted into a corresponding one of the plate holding grooves and a bulged section of a triangular cross section slidably fitted into a corresponding one of the slots, configured to partition the space into a plurality of chambers, wherein each of the linkage plates includes torque transmission surfaces on both surfaces of a corresponding one of the bulge sections to transmit rotational forces mutually between the outer rotor and the inner rotor and has a symmetrical cross sectional shape with a plane passing through a swing center of a corresponding one of the head sections as a center.