| 摘要 |
PROBLEM TO BE SOLVED: To stabilize combustion during cold operation, in a direct injection spark ignition type internal combustion engine which generates a normal tumble flow in a combustion chamber.SOLUTION: Grooves 14a, 14b are formed at a front side and a rear side of a top face of a piston 14. A small-capacity recess 14c is formed at the inner side relative to the grooves 14a, 14b. By forming the recess 14c, an air-fuel mixture, which is relatively higher in fuel concentration than the surroundings, can be collected into the recess 14c, and be introduced to an ignition plug 22 by rise of the piston 14, and thus, the ignitability of the air-fuel mixture can be enhanced. Accordingly, combustion can be stabilized during cold operation. Furthermore, in the combustion chamber 18, an intensity of a tumble flow, which is generated by the grooves 14a, 14b, from an exhaust side to an intake side can be increased, which can suppress the attenuation of the tumble flow caused by its collision with fuel, securing a disturbance intensity necessary for combustion after ignition.SELECTED DRAWING: Figure 2 |
