Patent ID: 7753664

Claim:
A rotary pump in which a fluid suction hole and a fluid discharge hole are opened or closed in accordance with the rotation of a rotor and fluid is compressed or pumped in accordance with the variation of volume of spaces, rotary pump comprising: a housing having a cylindrical interior space for allowing for the revolution of a rotary cylinder and provided with the fluid suction hole and the fluid discharge hole at perpendicularly adjacent locations on the circumference of the housing: a rotating shaft serving as a revolving shaft of a cuboidal rotary piston; a revolving shaft fitted on the rotating shaft and having a center axis eccentric to a center axis of the rotating shaft; the cuboidal rotary piston fitted on the revolving shaft to revolve about the revolving shaft and having convex arched upper and lower surfaces; the rotary cylinder installed to revolve in the cylindrical interior space of the housing while being closely received in the cylindrical interior space and internally defining rotary cylinder chambers for the sliding movement of the cuboidal rotary piston an expanded discharge pipe connected to the discharge hole and having a diameter larger than a diameter of the discharge hole to define an inwardly-extending protrusion between the discharge hole and the expanded discharge pipe; and a cover provided at the discharge hole to be opened outwardly in accordance with a pressure of fluid, thereby serving to prevent the fluid, which receives a high pressure at the outside of the discharge hole, from being pushed into an associated one of the rotary cylinder chambers.