Valve timing control device for an internal combustion engine

摘要

An engine valve timing control device is disclosed, in which the valve overlap amount is controlled according to the fuel property, thereby keeping the drivability unchanged even when the fuel is changed. A shortage of engine output and cold hesitation are prevented at the same time when the engine temperature is low. The device is for controlling the valve operation characteristic of an internal combustion engine, and comprises a variable valve mechanism capable of changing the valve overlap amount and a control unit for controlling the operating amount of the variable valve mechanism in accordance with the engine operating conditions. The property of the fuel burnt in the engine is determined as light, intermediate or heavy. Under the engine operating condition where the overlap amount otherwise is the same, the operating characteristic of the intake valve and the exhaust valve is controlled in such a manner that the overlap amount of the intake valve or the exhaust valve is smaller for the intermediate fuel than for the light fuel and smaller for the heavy fuel than for the intermediate fuel. Also, the control of the valve overlap amount can be corrected in accordance with the engine temperature.