No abstract

Fuel conversion efficiency is one of the main concerns in the field of internal combustion engine systems. Although the Otto cycle delivers the maximum efficiency possible in theory, the kinematics of the slider–crank mechanism of the conventional internal combustion engines makes it difficult to reach this level of efficiency in practice. This study proposes using the unique hypocycloid gear mechanism instead of the conventional slider–crank mechanism for the internal combustion engines to increase engine efficiency and minimize frictional power losses. The hypocycloid gear mechanism engine’s kinematics provides the means for the piston-rod assembly to reciprocate in a straight-line motion along the cylinder axis besides achieving a nonlinear rate of piston movement. As a result, this characteristic allows for a true constant-volume combustion, which in turn would lead to higher work output. An in-cylinder gas volume change model of the hypocycloid gear mechanism engine was developed and incorporated into the thermodynamic model for the internal combustion engine cycle. The thermodynamic model of the hypocycloid gear mechanism engine was developed and simulated using MATLAB/Simulink software. A comparison between the conventional engine and the hypocycloid gear mechanism engine in terms of engine performance characteristics showed the enhancements achieved using hypocycloid gear mechanism for internal combustion engine applications. The hypocycloid gear mechanism engine analysis results indicated higher engine efficiency approaching that of the Otto cycle.

This effort investigates the feasibility of using the Hypocycloid Gear Mechanism (HGM) as an alternative to the conventional slider-crank mechanism for Internal Combustion Engine (ICE) applications. Engines incorporating the conventional slider-crank mechanism are subjected to high frictional power losses mainly due to the piston-rod assembly and the associated complex motion of the connecting rod. The unique HGM engine provides the means for the piston-rod assembly to reciprocate in a straight-line motion along the cylinder axis, thus eliminating the piston side-thrusting into the cylinder wall. To analyze the performance advantages of the HGM engine, a Matlab/Simulink model is developed for the simulation of a single-cylinder HGM engine from the throttle to the crankshaft output. The model integrates several sub-models for combustion, gas flow, heat transfer, and friction power loss of the internal gear train meshes, rolling bearings, and sliding bearings. The design of the planetary crank gearing system to satisfy the design specifications of ICE, has been derived using standard design procedures provided by AGMA. Calculated efficiency and power diagrams are plotted and compared with the performance of conventional engines in the literature. The results show that the HGM can satisfy modern ICE design requirements, achieve better engine performance characteristics, and minimize the frictional power losses. The HGM engine achieved lower frictional power losses by an average 33% of the conventional engine losses while its mechanical efficiency is enhanced by up to +24% with respect to the conventional engine.

No abstract