US Patent 7887285 Pump and fluid supplying apparatus

A pump includes a rotatable rotor installed in a motor part and at least one impeller installed in a pump part, capable of being rotated together with the rotor in unison. The rotor and the impeller are accommodated in a casing, and the impeller has an inlet at an inner periphery thereof and an outlet at an outer periphery thereof. A housing is arranged in both sides of an axial direction of the impeller and has an outer peripheral part coupled to the rotor at a rear side portion thereof, and the outer peripheral part is projected outwards further than a gap between an outer peripheral surface of the rotor and an inner peripheral surface of the casing in which the rotor is rotatably accommodated.