| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise by keeping the pressure difference between the pressure inside a combustion chamber when an intake valve is opened and the pressure on an intake port side negligible all the time, and decreasing pulsation caused by blow-back. SOLUTION: At the time of the compressed ignition combustion, a negative valve overlap period when both intake and exhaust valves 6, 7 are closed together around the exhaust top dead point is formed by delaying the angle of the valve opening time of the intake valve 6, while advancing the angle of the valve closing time of the exhaust valve 7. The valve opening time of the intake valve 6 is set on the delayed angle side than the crank angle in a symmetrical position holding the valve closing time and the exhaust top dead point of the exhaust valve 7 in between. The pressure difference between the pressure inside the combustion chamber 3 when the intake valve 6 is opened and the pressure on the intake port 4 side is reduced by setting the valve opening period of the intake valve 6 on the delayed angle side than the valve closing period of the exhaust valve 7, thereby suppressing the blow-back by a residual gas.
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