| 摘要 |
In the present invention, the piston (4) of this direct injection type diesel engine (1) has a re-entrant cavity (6), and a fuel injection nozzle (7) with multiple nozzle holes is arranged on the center line thereof. The cavity (6) has a lip portion (42), which is the portion thereof having the smallest diameter, positioned below the piston crown surface (43) and a pocket portion (44) formed above the lip portion (42). The pocket portion (44) is positioned at a height at which a pilot injection injected before top dead center during engine idling is oriented, and the position of the wall surface (45) is set such that the tip of injection spray does not collide strongly therewith. The fuel from the pilot injection temporarily stays in the pocket portion (44) and moves inside the cavity (6) by means of a subsequent squish flow. Accordingly, an increase in unburned hydrocarbons (HC) is suppressed. |
