Patent ID: 7118361

Claim:
A rotary piston comprising: a shaft to rotate about a longitudinal axis; a rotor centrally secured to the shaft, the rotor having ends and a cylindrical side wall; a rotor disk at each end of the rotor to rotate with the rotor; a housing encasing the rotor, the housing having interior end walls confronting the rotor ends and an interior side wall opposite the rotor side wall, with fluid inlet and fluid outlet ports in the housing side wall, a first portion of the interior side wall of the housing being cylindrical and curved with constant radius over an angle of approximately 180°, this portion being spaced a constant distance from corresponding portions of the side wall of the rotor, a second cylindrical portion of the interior side wall of the housing continuing from extremities of the first portion of the interior side wall and being of curvature of greater radius, the wall of the rotor meeting the interior side wall of the housing at a point between inlet and outlet ports about midway on the second portion, the inlet and outlet ports being spaced from each other in this second portion of the interior side wall of the housing; two or more planar vanes extending from end to end in the rotor and having inner and outer edges extending parallel to the axis of the rotor, each vane movable in slots in the rotor radially inwardly and outwardly between retracted and extended positions with respect to the cylindrical side wall of the rotor, the vanes having side shoulders which slide in corresponding guide slots in the rotor disks, with outer ends positioned always in contact with the interior side wall of the housing, which side wall exerts a cam action on these outer ends, the vanes being equally spaced from adjacent vanes about the rotor and located on the rotor such that there is always at least one vane positioned between inlet and outlet ports; biasing means to urge each of the vanes radially within its associated slot towards extended position, so that during operation, the outer end of each vane is constantly positioned in contact with a corresponding portion of the interior side wall of the housing; the rotor, housing and vanes constructed so that, during operation of the pump, fluid entering the housing is carried by the rotor in compartments formed between adjacent vanes, the rotor side wall between those vanes, the rotor disks and the interior side wall of the housing, until the adjacent vanes encompass the outlet port whereby the fluid is allowed to escape.