Theoretical Research on the Power Transmission System of a Twin-rotor Piston Engine

In order to increase the power density of the piston engine, the power transmission system of a twin-rotor piston engine is proposed, which is composed of an energy conversion assembly and a differential velocity drive mechanism assembly. The major parts of the energy conversion assembly include a housing and two interdigitated rotors each having plurality of diagonally opposed vane pistons which separate the housing and form working chambers. The differential velocity drive mechanism is composed of the hypocycloidal mechanism and the crank rock mechanism, which constrain the two rotors fixed inside the housing rotating with periodical nonuniform velocity. Thus the volume of the working chambers varies, and opens and closes periodically. The structure and the working principle of the engine are discussed. The mathematical modeling of the energy conversion assembly and the conditions of intake, compression, combustion, and exhaust are presented. The displacement and the instantaneous flow of the engine are deduced. The kinematic model of the engine mechanism is presented and analyzed. The results show that the twin-rotor piston engine theoretically should be able to generate higher volumetric output and power density due to multiple utilization of work space during one revolution, and higher uniformity of torque due to multiple work strokes during one revolution than the piston engines available.