| 摘要 |
<p>PURPOSE:To improve the scavenging efficiency due to the increasing of effective opening area by a pair of exhaust ports during low revolution operation of an engine by a method wherein a variable mechanism, for controlling that the valve timing of one exhaust valve is turned at a delay side, is provided during high load high revolution operation of the engine. CONSTITUTION:A variable mechanism is non-operational condition during low revolution operation of an engine. On the other hand, during high revolution and high load operation of the engine, both variable mechanisms 11, 12 are operated and controlled, that is, the valve timing of the second exhaust valve 6b of a pair of exhaust valves is turned at a delay side by the variable mechanism 12, also the valve timing of the second intake valve 5b of a pair of intake valves is turned at the delay side by the variable mechanism 11. Therefore, the total valve opening duration of both exhaust valves is increased by a delay side lag of the valve timing of the exhaust valve 6b, accordingly, the scavenging efficiency of the exhaust operation can be improved. Further, the total valve opening duration of both intake valves is increased by the delay side lag of the valve timing of the intake valve 5b, accordingly, the filling efficiency of the intake operation can be improved.</p> |
