Induction system of multi-cylinder engine

Abstract

An induction system for a multi-cylinder internal combustion engine that improves fuel efficiency and reduces the emission of unwanted exhaust gas constituents, particularly at the low and medium load conditions. The engine induction system comprises a plurality of separate carburetor barrels which, at least under some running conditions, serve cylinders separately from each other through main induction passages. One carburetor barrel is provided with a different fuel discharge system than the other carburetor barrels for accommodating a certain engine operating condition. A separate sub-intake system connects this carburetor barrel with other cylinders not normally served by the particular carburetor barrel in question. This sub-intake system has a substantially smaller cross-sectional area in the main intake system so that the charge drawn into the cylinders through the sub-intake system enters at a substantially higher velocity. This improves combustion by creating turbulence under at least some operating conditions. Several embodiments of throttle valve constructions are disclosed for insuring complete closure and sealing of at least one throttle valve of the induction control system for precluding leakage. In some embodiments this is accomplished by providing a resilient section in the throttle body and in other embodiments the result is obtained by providing a resilient seal on the periphery of the throttle valve.