Patent ID: 7891958

Claim:
A pump comprising: a pump part including an impeller having a plurality of blades for sucking and discharging a liquid; a pump case accommodating the pump part; a rotor installed on the impeller to rotate the impeller; a motor part accommodating a stator disposed around an outer periphery of the rotor to drive the rotor and a driving circuit for controlling the stator; a partition member for isolating the motor part from the pump part to protect the motor part therefrom; a shaft fixed to the pump case and the partition member at both ends thereof; a reservoir space disposed in the impeller; an extra passage provided between the rotor and the partition member and connected to the reservoir space to introduce the liquid thereto from the blades; and one or more reflux passages, formed in the impeller, for flowing the liquid in the reservoir space back to the blades, wherein the impeller is rotatably attached to the shaft and rotates around the shaft.