The Effect of an Intake Pipe System on the Fuel Flow Amount of a Small Type Two-Stroke Cycle Engine

Abstract

To examine the influence of the pressure wave in an intake pipe system on the fuel flow quantity of a crankcase compressed two-stroke cycle gasoline engine, the authors carried out some experiments and then analyzed numerically on the unsteady characteristics of a simplified carburettor. Some conclusions reached are summarized as follows. (a) The fuel flow quantity from a carburettor decreases in inverse proportion to the amplitude of the pulsation wave acting on the carburettor throat and that is governed by the matching condition q^*=15·a/N(L_S+Δl). (b) When the throttle valve of carburettor is a small opening, the fuel flow quantity increases with the engine speed and the length of the main fuel pipe system because of the inertia effect of fuel liquid column in the main fuel pipe. (c) To prevent the variation of excess air ratio with the engine speed, the utilization of a Helmholtz resonator with elastic wall is effective.