Low emissions combustion engines for motor vehicles

As an alternative to installing exhaust treatment devices on conventional internal combustion engines, modification of the basic combustion process can, in principle, yield large reductions in vehicle exhaust emissions. Such modifications are the basis for operation of stratified charge engines of both open and prechamber types, as well as divided chamber or staged combustion engines, all of which have demonstrated advantages from the standpoint of emissions control. Additionally, continuous combustion systems as employed in gas turbine, Rankine, and Stirling cycle engine applications are amenable to modification for reduced emissions. A description is given of the technical principles common to modification of the above combustion systems for low emissions. Exhaust emissions typical of each system are interpreted in terms of these combustion principles. Discussion is limited to combustion system behavior and does not include consideration of the overall merit of each of the various power plants for automobile application.