An investigation of a hypocycloid mechanism based twin-rotor piston engine

A unique mechanism is investigated in this paper to show the working principles of a novel hypocycloid twin-rotor piston engine (HTRPE), which provides the basis for the structural design, kinematic and dynamical analysis necessary to realize the engine. As a critical system for the HTRPE, the differential velocity mechanism is examined first by decomposing it into two non-uniform motion mechanisms and one hypocycloid mechanism, which allows an evaluation of different options of design parameters. Then analytical expressions are derived to calculate the rotor angular velocities and the relative angular velocities of pairs of rotors for a detailed performance analysis. Based on the results of this analysis a prototype HTRPE is proposed and benchmarked with both a conventional reciprocating and a Wankel engine. It is shown that the new engine outperforms the other two engines in key engine features including combustion gas force transmission, volumetric change of working chambers, power frequency, piston velocity and displacement, demonstrating that HTRPE is very promising as a more energy efficient engine due to its high compactness and power density, and consequently lightweight design.