US Patent 6282898: Operation of forced induction internal combustion…

Abstract

A spark ignition internal combustion engine having at least one combustion chamber and an operating cycle with induction, compression, power and exhaust phases, said engine having a forced induction system including an intake air compressor supplying intake air to the engine through an inlet tract comprising at least one throttle, at least one intake port and means to introduce metered quantities of fuel into the inlet tract; wherein the compressor is designed to boost intake air pressure by more than one atmosphere throughout that portion of the operating range of the engine which corresponds to significant opening of the at least one throttle, the at least one throttle and at least one intake port conjointly providing sufficient throttling of the intake air flow over said portion of the operating range such as to provide substantially adiabatic expansion of the air delivered by the compressor through the inlet tract, while causing each combustion chamber to be charged with sufficient air/fuel mixture during the induction phase that the pressure in each combustion chamber at the end of the compression phase is at least ten atmospheres over said portion of the operating range and the combined temperature and pressure conditions in the combustion chamber during the compression phase remain outside those giving rise to pre-ignition, the means to introduce metered quantities of fuel into the inlet tract being calibrated to provide substantially stoichiometric quantities of fuel relative to the air passing through the tract over said portion of the operating range.