COMBUSTION CHAMBER STRUCTURE OF DIRECT INJECTION TYPE DIESEL ENGINE

摘要

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. The inlet lip 11 is formed at a position lower than the top surface of the piston 9 by an inner periphery of the bottom of the depression 24 and a combustion chamber wall 12 rising from a bottom of the cavity 10.