| 摘要 |
PURPOSE:To prevent the cancel-out of swirls, by maintaining one of two intake valves in its closed condition in a low speed running range, and as well to enhance the efficiency of charging of air in a high speed running range, by making the opening period of the one of two intake valves longer than that of the other. CONSTITUTION:Upon low speed running a control valve 58 is closed, and a shutoff valve 53 communicates a hydraulic chamber 43 with an accumulator 51 in association with the output of an engine speed sensor 60. Accordingly, a cam 23A merely reciprocates a tappet 22A, but an intake valve 21A is maintained in its closed condition. The supply of fresh air to a combustion chamber is made through another intake valve so that the cancel-out of swirls from two intake valves may be prevented. In a high speed running range the intake valve 21A is subjected to open and close control in addition to another intake valve, and since the opening period of the intake valve is so long that fresh air is sufficiently sucked into the combustion chamber. |
