| 摘要 |
PROBLEM TO BE SOLVED: To enable sufficient scavenging in a cavity in a central portion on a piston crown surface in an engine in which a compression self-ignition is performed when a geometric compression ratio is 15 or more.SOLUTION: A part of a bevel part 1a of an intake valve 1 is overlapped with a cavity 11 formed in a piston 10. A crown surface of the piston 10 has a valve recess 15A (15B, 16A, 16B) for preventing interference of the bevel part 1a with the piston 10 such that the valve recess 15A (15B, 16A, 16B) is continued to the cavity 11. A recess side opening end position 40 that is a position on an opening end for a combustion chamber of a valve recess 15A for an intake valve 1A and is nearer to an exhaust valve 2A, is in the same position as a port side opening end position 41 that is a position on an opening end for the combustion chamber of an intake port 5 and is nearer to an exhaust valve 2A, or in a position nearer to the exhaust valve 2A than the port side opening end position 41. |
