Alternative Crankshaft Mechanisms and Kinetic Energy Recovery Systems for Improved Fuel Economy of Passenger Cars

The paper presents a novel design of a variable compression ratio advanced spark ignition engine that also permits an expansion ratio that may differ from the compression ratio therefore generating an Atkinson cycle effect. The stroke ratio and the ratio of maximum to minimum in-cylinder volumes may change with load and speed to provide the best fuel conversion efficiency. The variable ratio of maximum to minimum in-cylinder volumes also improves the full load power output of the engine. Brake specific fuel consumption maps are computed for a gasoline engine 2 Litres, in-line four, turbocharged and direct injection showings significant fuel savings during light and medium loads operation as well as improvement of full load output and fuel efficiency. Results of vehicle driving cycle simulations of a full size car with the 2 Litres engine and of a compact car with a downsized 1 litre engine show dramatic improvements of fuel economies for similar to a Diesel fuel energy usage and CO2 production. Coupled to advanced PWT using mechanical kinetic energy recovery systems (KERS) to recover the braking energy thus reducing the thermal energy supply in the following acceleration these engines offer better than hybrids fuel economies.