| 摘要 |
<p>PURPOSE:To improve fuel consumption performance and operability in a practical area by providing a plurality of cam shafts which open and close respectively an intake valve and an exhaust valve, and properly advancing/delaying the cam shafts in angle. CONSTITUTION:Valve timing changeover mechanisms 10 are arranged on both an intake side cam shaft 11 for opening and closing an intake valve, and an exhaust side cam shaft 11 for opening and closing an exhaust valve. A control device 25 controls a solenoid valve 22 of the valve timing changeover mechanism in the intake side cam shaft and a solenoid valve 22 of the valve timing changeover mechanism of the exhaust side cam shaft. The intake side cam shaft is advanced in angle from the position of idling under low/medium speed and high load conditions. The exhaust side cam shaft is delayed in angle under the low/medium speed and high load conditions. With such an arrangement, blowing back is prevented under the low/medium speed high load conditions, for improving intake charging efficiency and increasing a torque. In addition, a valve overlapping rate is increased and pumping loss is reduced.</p> |
