Dynamics in the Inlet System of a Four-Stroke Single-Cylinder Engine

Abstract

This paper presents the results of a recent investigation of the inlet process in a four-stroke, single-cylinder engine with an inlet pipe. The effects of inlet-pipe length, inlet-pipe diameter, inlet-valve timing, and some other design parameters were studied. The results showed that the dynamic effect of the inlet pipe on the engine volumetric efficiency was associated with (a) the process of accelerating the inlet-pipe air column during the first part of the inlet stroke, and taking advantage of the ramming of the air column during the last part of the same inlet stroke; and (b) the action of the standing wave set up in the air column during the preceding cycle. By a suitable choice of inlet pipe and valve timing, a considerable gain in volumetric efficiency over that for zero pipe could be obtained over a wide range of engine speed.