DIRECT INJECTION ENGINE AND ITS PISTON

摘要

PROBLEM TO BE SOLVED: To suppress discharging of emission of HC or the like, in a direct injection engine performing fuel injection executing pilot injection prior to main injection. SOLUTION: Six ceramic films 33 are formed in a peripheral direction at almost equal intervals in a position hit by fuel injected from six nozzles of an injector 8, in a lip part of a top land 3b in a piston 3 of a direct injection diesel engine. The ceramic film 33 has vaporization promoting action, pilot injection is executed to be directed to the ceramic film 33. The injection timing thereof is set to the timing moving vaporized fuel in the vicinity of the nozzle of the injector self ignited in this spot by a squish flow strengthened when the piston 3 approaches the top dead center. Vaporized fuel (including also liquid drop) existing in the vicinity of a surface of the top land 3b flows into a cavity 3a by a squish flow, to generate concentric combustion in the cavity 3a. Consequently, a high temperature is generated in an injection region of main injection.