Patent ID: 7861685

Claim:
A direct fuel injection diesel engine comprising: a piston of which a height of a top face changes in a circumferential direction, the piston having a recessed cavity defined in a central part thereof by a bottom wall portion connected to a peripheral wall portion by a curved wall portion therebetween, and the piston having a piston central axis to which the curved wall portion of the piston is concave relative thereto and the bottom wall portion is oblique relative thereto, and a fuel injector which injects fuel oriented in a plurality of directions in the circumferential direction of an interior of the recessed cavity defined in the central part of the piston, wherein the peripheral wall portion of the cavity in a direction in which the height of the top face of the piston is low is inclined to open radially outward, and wherein a collision angle (Î±) at which fuel injected in a direction in which the height of the top face of the piston is high collides with the cavity is set larger than a collision angle (Î²) at which fuel injected in a direction in which the height of the top face of the piston is low collides with the cavity.