US Patent 7188602 Concentric internal combustion rotary engine

An internal combustion rotary engine includes a housing having an inlet and an outlet and a rotatable rotor centrally mounted within the housing. The rotor includes a plurality of pockets located about its circumference, the rotor further being connected to a rotor shaft. A rotatable elliptical body is disposed in each of the plurality of pockets. Each rotatable elliptical body is coupled to respective planet gears and each respective planet gear is meshed with a centrally disposed fixed sun gear. An ignition source is disposed in each of the plurality of pockets for igniting a fuel/air mixture. During operation of the internal combustion rotary engine, for each 360° rotation of the rotor, each elliptical body rotates through 720°.