PISTON FOR DIRECT INJECTION ENGINE, AND DIRECT INJECTION ENGINE

摘要

PROBLEM TO BE SOLVED: To reduce emission and improve fuel consumption, by promoting vaporization of fuel adhering to a wall surface of a piston. SOLUTION: Six ceramic films 17 are formed in a peripheral direction at almost equal spaces in a position hit by fuel injected from six nozzles of an injector, in an internal peripheral side wall of a cavity 16 of a piston 3 in a direct injection diesel engine. The ceramic film 17 consists of a flame spraying film of zirconium. The zirconium has such a catalytic effect of one kind that it promotes vaporization of fuel by shifting a wall surface temperature of fuel's film boiling to a high temperature side. An area of the ceramic film 17 is suppressed to a required minimum limit in the area less than an injection angle of the injector, so as to prevent a suction air amount from reducing by a heat insulation effect of the ceramic film 17.