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Spray formations of three injection directions against swirl have been investigated by means of 3D numerical calculation, in-cylinder measurement, and engine performances tests. A direct injection type engine which has a single hole nozzle and a spark plug, has been operated, and three injection directions; a forward (same) direction, a reverse one, and a right-angled (central) one against a swirl direction, have been selected. Three types of intake port, futhermore, have been selected owing to create three types of in-cylinder flow, low swirl, middle swirl, and high swirl. Spray formations in 3D cylinder flow have been investigated by using a ‘KIVA’ code. Initial conditions of in-cylinder flow are based on data which have been measured in three dimensional by a LDV system under a motoring operation. Analysis results of spray formations by numerical calculations can explain well data of engine performance tests qualitatively, and some interesting results have been obtained.

The new combustion method in DISC engine has been developed. It has a double structure combustion chamber characterized as ‘Caldera’. The chamber is constructed by a center cavity for the purpose of forming a stable mixture around a spark plug electrode, and by an outer cavity which has a role of a main chamber. This method makes possible a perfect un-throttling operation, and a fuel consumption equal to a diesel engine is achieved. With regard to an out-put of DISC engine, a stoichmetric combustion and a high torque are achieved by controling a fuel injection timing with an electro-magnetic injection system device. With regard to emission regulations, a heavy EGR include residual gas decreases greatly NOx and HC emissions simultaneously, and which suggests a possibility to achieve LEV/ULEV regulations.