Spark ignition engine with cylinder head combustion chamber

Abstract

An engine is provided with a combustion chamber that is separate from the main cylinder displacement/swept volume area and mounted in a cavity in the cylinder head and having a connection between the two by a channel of small cross-sectional area providing high velocity flow of fresh air from the cylinder into the combustion chamber to aid in fuel evaporation and fuel-air mixing, thereby providing complete combustion wholly within the separate chamber. Only intake air is taken into the engine during the intake stroke. A separate valve is provided at the exit of the combustion chamber to the connecting channel for cold start operation, the valve remaining closed until the ratio between the pressures in the cylinder under compression and in the combustion chamber exceeds two, i.e., establishing sonic flow in the channel, whereby a rush of fresh air into the combustion chamber upon opening of the valve and injection of fuel and ignition thereof causes complete combustion wholly within the combustion chamber. The pockets of fresh air stored in the main cylinder dilute the burned gas during the expansion stroke of the piston in response to the intense vortex flow out of the combustion chamber to the main chamber therefor promoting post oxidation of any unburned hydrocarbons.