Technical Paper
New Mixture Formation Technology of Direct Fuel Injection Stratified Charge Si Engine (OSKA) - Test Result with Gasoline Fuel
1988-09-01
881241
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 around the impinging part and ignition is accomplished near the center of the mixture, steady, instantaneous and high-speed combustion is possible. As the fuel-air mixture is formed mostly 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 employ a higher compression ratio than that of the conventional premixed SI engine. Experiments with a single cylinder prototype (4-stroke cycle) engine with gasoline fuel showed that the maximum BMEP was 1.0 MPa and the maximum brake thermal efficiency was 37.7 % (217 g/kW.h).
