| 摘要 |
A spark-ignited direct cylinder fuel injection engine is provided with a combustion chamber formed in a depression on the surface of each piston, and a direct cylinder fuel injection valve spraying a fuel mist directly in the combustion chamber. In the wall of the combustion chamber an arc-shaped first wall surface region is located on the upstream side of the combustion chamber with respect to the swirl flow direction of the intake air. Continuous with the first wall surface region, a straight second wall surface region is formed at the downstream side of the first wall surface region. An arc shaped third wall surface region is formed at the downstream side of the second wall surface region. A spark plug is positioned so that it protrudes into the depressed combustion chamber at the region near the second wall surface region when the piston is positioned at its top dead center. Fuel is injected into the first wall surface region part of the combustion chamber, and carried by the intake swirl flow toward the third wall surface region part of the combustion chamber while it is being diffused and vaporized. Therefore, when flowing along the second wall surface near the spark plug, the injected fuel forms an ignitable air-fuel mixture, thus stable ignition, by the spark plug, is obtained regardless of the amount of the fuel injected into the combustion chamber.
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