Induction system for an internal combustion engine

Abstract

An induction system for an internal combustion engine consisting of a relatively large main induction system and a relatively small sub or auxiliary induction system. A throttle valve arrangement is provided so that a charge, issuing from a charge forming device, is delivered to the engine combustion chambers through the small auxiliary induction system during idle and light load operation. This increases the velocity of the charge entering the combustion chambers and the turbulence in the chamber at the time of ignition. As a result, combustion propagation is increased and both fuel economy and cleanness of running are improved. In higher loads, an increasing proportion of the charge is delivered to the combustion chambers through the main induction passage so as to provide good volumetric efficiency and insure against the loss of performance. In accordance with this invention, the auxiliary induction passage discharges into the chambers in a direction that is tangent to the cylinder, which crosses the gap of the spark plug and which passes across the exhaust and intake valves in that sequence.