Patent ID: 8753100

Claim:
An expander comprising: a case with a cylindrical inner wall having an operating radius extending from a case axis to form an operating chamber; a main rotor carried within the case by an axle and having a lobe with a major radius equal to and concentric with the operating radius, said lobe having an advancing surface and a retreating surface, said main rotor having a minor radius defining a body; two peripheral rotors diametrically opposed with respect to the case axis and rotating within rotor chambers extending from the case, each rotor having a radius equal to the minor radius and a center of rotation located at twice the minor radius from the case axis, each of said peripheral rotors rotating in uniform circular motion with the main rotor in sealing contact with the body and having a sculpted recess for receiving the lobe of the main rotor with upper and lower cylindrical extensions extending longitudinally from each extent of the recess; said case incorporating a cover, said cover and said case each having a sealing surface for an upper surface and lower surface of the main rotor lobe respectively and said lobe including a bore having an aperture in at least one of the upper or lower surface communicating with a first conduit in the axle, said first conduit receiving pressurized gas for expansion, said upper and lower cylindrical extensions including at least one transfer depressions in one of said upper and lower cylindrical extensions in each peripheral rotor for communication with said aperture, an expansion volume formed by a first of said peripheral rotors and the retreating surface of the lobe; said advancing surface of the lobe incorporating a port communicating with a second conduit in the axle and displacing expanded gas in the operating volume between the advancing surface of the lobe and a second of the peripheral rotors.