Abstract: An engine control system controls an internal combustion engine so that some of a plurality of cylinders in a multi-cylinder internal combustion engine are made to rest and reduced-cylinder operation takes place. Each cylinder comprises a piston, an intake valve and an exhaust valve. In a resting cylinder during reduced-cylinder operation, when the piston moves downwards, the engine control system opens both the intake valve and the exhaust valve, and when the piston moves upwards, the engine control system opens the intake valve and closes the exhaust valve.

Abstract: An engine control system controls an internal combustion engine so that some of a plurality of cylinders in a multi-cylinder internal combustion engine are made to rest and reduced-cylinder operation takes place. Each cylinder comprises a piston, an intake valve and an exhaust valve. In a resting cylinder during reduced-cylinder operation, when the piston moves downwards, the engine control system opens both the intake valve and the exhaust valve, and when the piston moves upwards, the engine control system opens the intake valve and closes the exhaust valve.

Abstract: A combustion chamber structure for a direct injection diesel engine is provided which can increase recirculated amount of exhaust gas while avoiding generation of black smoke and deterioration of fuel efficiency as much as possible. Disclosed is a combustion chamber structure for a direct injection diesel engine having a cavity 10 on a top surface of a piston 9. The cavity is concave to provide a majority of the combustion chamber. Fuel is injected from a center of a cylinder top radially into an inner periphery of the cavity 10 to self-ignite. A depression 24 is formed at an outer periphery of the cavity 10 and is sunken relative to the top surface of the piston 9 to provide a step. The depression 24 has a bottom with an outer periphery gradually rising radially outwardly in modestly curved surface to the top surface of the piston 9.