| 摘要 |
PROBLEM TO BE SOLVED: To effectively burn deposits clinging to a spark plug by means of the false discharge of the spark plug. SOLUTION: If the worsening of a combustion condition is detected from the frequency of misfires or the like (S2) during stratified combustion in which compression stroke injection is performed (S1), a spark plug is discharged just before fuel injection (S3), so that deposits clinging to the spark plug are burnt by false discharge. The higher the concentration of gas in a cylinder, the higher the discharge voltage of the spark plug, and sparks are unlikely to scatter between normal gaps when the discharge voltage is high, so that by causing the false discharge as late as possible during compression stroke, i.e., under a condition in which the concentration of gas in the cylinder is as high as possible, leakage currents conducted through the deposits can be increased.
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