| 摘要 |
PURPOSE:To enable actual compression ratio to be changed so as to increase a margin of knocking and promote an output and fuel comsumption to be improved, by providing a selector device of closing timing of an intake valve and a selective control means of ignition timing and air-fuel ratio in accordance with a signal from a valve detecting means. CONSTITUTION:If a switch 41 is turned off when an engine is driven at a low speed, an electronic control means 40 switches selector valves 33, 34 to a right position. Then an accumulator 35, actuating a piston by its oil and engaging an intake valve rocker arm 26 with a low speed cam 24B so as to advance the closing timing of an intake valve in a direction of the bottom dead center and increase actual compression ratio, can prevent the decrease of an output and the worsening of fuel consumption in the engine in its low speed and low load operational range. While the engine is driven by reading the characteristic ignition timing in a delay angle side and the characteristic air-fuel ratio in a rich side from a memory of the control means 40 on the basis of a signal from an engagement position detecting means. Then the closing timing of the intake valve is delayed so as to decrease the actual compression ratio because the rocker arm 26 is adapted to a high speed cam 24A when operation of the engine is transferred to a high speed, and the supercharge pressure increases, improving an output further increasing a margin of knocking. |
