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This paper describes application of sintered silicon nitride to the swirl lower-chamber in order to improve performance of turbocharged diesel engines. Various stress analyses by finite element method and stress measurements have been applied to determine the design specifications for the component, which compromise brittleness of ceramic materials. Material development was conducted to evaluate strength, fracture toughness, and thermal properties for the sintered bodies. Ceramic injection molding has been employed to fabricate components with large quantities. In the present work. Quality assurance for the components can be made by reliability evaluation methods as well as non-destructive and stress loading inspections. It is found that the engine performance with ceramic component has been increased in the power out put of 9ps as compared to that of conventional engines.

The new idea incorporates an impinging part in the central piston cavity. A relatively low injection pressure, lower than that of a conventional IDI Diesel engine, and a single hole fuel nozzle are used. The fuel spray is injected against the impinging part, spreads and forms a fuel-air mixture. Since a comparatively rich fuel-air mixture always stays aroung the impinging part and ignition is accomplished near the center of the mixture, steady, instantaneous and high-speed combustion is possible

A new type of internal combustion engine has been developed. The new idea incorporates an impinging part in the central piston cavity. The fuel spray is injected against the impinging area, spreads and forms a fuel mixture. Since a comparatively rich fuel mixture always stays around the impinging part and ignition is accomplished at the center of the rich fuel mixture, steady, instantaneous and high-speed combustion is possible. As the fuel mixture is always formed in the cavity, there is little fuel in the squish area. Therefore, it is possible to prevent end-gas knocking, and in spite of the use of spark ignition, to operate the engine at higher compression ratio than a conventional premixed SI engine. Experiments with methanol fuel showed that BMEP was 1.1MPa and the maximum brake thermal efficiency was 42%. The combustion noise was lower than that of diesel engine. Brief tests with gasoline showed a maximum brake thermal efficiency of 36%. (A) For the covering abstract of the conference see IRRD 853507.

A new scavenging method for two-stroke cycle engines - Multi-Layer Stratified Scavenging (MULS) - has been developed. The MULS method is achieved by separating the mixture generated by the carburetor into a rich mixture and a lean mixture between the inlet manifold and the scavenging ports, and by finely controlling the scavenging flows. With the MULS method the thermal efficiency and HC emissions of two-stroke cycle gasoline engines are considerably improved without sacrificing the brake specific power output and mechanical simplicity.