Roller displacement motor

A roller-type positive displacement fluid machine including at least a motor unit capable of working reciprocally as a pump and a compressor, the motor unit comprising a housing formed by a cylindrical stator ring and first and second end plates, the stator ring having a cylindrical inner surface with a generally elliptical profile, a shaft rotatably supported within the housing for rotation about an axis, a cylindrical rotor fixed on the shaft within the housing, the rotor having a circular rotor profile and a plurality of slots disposed at equal angular intervals about the surface of the rotor, each slot being defined by a substantially planar leading face and a substantially planar trailing face, a cylindrical roller disposed in each slot, the rollers being sized to have a minimum clearance with respect to the slots so that they freely move radially within the slot for contact with the inner surface of the stator ring, the points of contact between the roller and the leading face over one complete revolution of the rotor describing a geometrical locus of points which define an imaginary closed curve, and the space defined by two consecutive rollers, the rotor surface, and the inner surface of the stator ring constituting a working fluid chamber, the trailing face of each slot having an open channel therein connecting the portion of the slot beneath the roller with the surface of the rotor and the working chamber, and fluid inlet ports and outlet ports disposed within said housing, the inlet ports being entirely located at a radius less than the radius of said imaginary curve formed by said geometrical locus of points and such that the inlet ports may be opened and closed by the leading and trailing faces, respectively, of said slots, and said outlet ports being entirely located at a radius greater than the radius of said imaginary curve formed by said geometrical locus of points and such that the outlet ports are opened and closed by said rollers contacting the inner surface of the stator ring, and wherein the outlet ports are angularly located such that they are opened at substantially the position of a roller at which the roller has reached its maximum radial stroke and will start an inward stroke, and the inlet ports being angularly located such that they are closed by the trailing face of each slot.