| 摘要 |
PROBLEM TO BE SOLVED: To prevent atomization fuel from being adhered at a piston having a concavity part formed at its top surface without reducing a compression ratio.SOLUTION: A concavity part 9 is constituted of the first group of concave grooves 7 facing toward an opening of a fuel injection hole of an injector 5 and the second group of concave grooves 8 positioned between the adjoining first concave grooves 7. The concavity part 9 is formed in such a shape that outer ends 7a of the first concave grooves 7 are protruded outward in a radial direction and outer ends 8a of the second concave grooves 8 are also protruded toward a center of axis 10 to make a petal having their irregularities continuous in smooth. A central part 11 of the concavity part 9 has substantially the same depth over its entire circumference and the first concave grooves 7 are deeper than the second concave grooves 8 as they are far away from the central part 11. Since a dispersion distance of the atomized fuel can be increased without increasing a volume of the concavity part 9, it is possible to prevent adhesion of fuel without changing the compression ratio.SELECTED DRAWING: Figure 1 |
