Experimental Study of a Novel 4 Stroke Spark Ignition Geared-Hypocycloid Engine

Abstract

The aim of this work was to develop a geared-hypocycloid engine to be able to determine its feasibility and performance characteristics. This was done by modifying an existing engine with a custom-designed geared mechanism to replace the conventional slider-crank mechanism (crankshaft). The geared-hypocycloid engine design takes advantage of the hypocycloid concept, more specifically when the diameter of the inner circle is equal to the radius of the outer circle. In this specific case, the piston moves only in the longitudinal direction along the cylinder, and in a true sinusoidal motion. This motion results in reduced mechanical losses by friction of the piston head against the cylinder due to very little side forces action on the piston, as well as the piston remaining near the top-dead center, and thus in higher in-cylinder pressure, for a longer period of time. Consequently, higher torque and power output can be achieved with no increase in fuel consumption, resulting in higher efficiency. Vibrations were found to be considerably low but the geared mechanism showed high noise during operation. The engine performance parameters such as the rotational speed, torque output and fuel consumption were measured on a dynamometer. This data allowed for power, specific fuel consumption and overall efficiency to be calculated.