| 摘要 |
<p>PROBLEM TO BE SOLVED: To avoid knocking more effectively through variable control of opening and closing timing of an intake valve. SOLUTION: A variable valve drive mechanism of such a type that the operating angle is changed, is used for an intake valve, and accordingly, the closing timing can be greatly changed while the opening timing is held to be substantially constant. During high temperature and high load operation of an engine, a frequency of knocking detected by a knocking sensor becomes larger, the ignition timing is retarded, and simultaneously, an actuator is operated so as to enlarge the operating angle. As the closing timing of the intake valve is delayed, an actual compression ratio is lowered so as to avoid knocking. When the operating angle is changed up to a desired value, the ignition timing is advanced to its original value, thereby it is possible to prevent the temperature of exhaust gas from rising.</p> |
