Variable Valve Timing With Only One Camshaft Actuator for a Single-Cylinder Engine

The control of the valve timing is an important factor to increase the efficiency and to optimize the emission of the combustion engine. For small engines, it is difficult to equip each valve with a separate actuator because it increases the system complexity. Changing the valve times in a limited range is possible with only one actuator. This actuator can be used to achieve an angle-dependent acceleration and therefore a variation of the valve stroke. A small model of the camshaft drive was proposed to show the angle-dependent valve lift. This paper also presents several trajectories for the camshaft actuator to change the valve times and their influences on the combustion process. Changing the valve times also leads to the possibility of controlling the air mass flow without changing the fundamental speed of the engine. This fact increases the throttleless operation range of the combustion engine. An adaptive controller was designed which is able to increase the dynamic of the controlled system without changing the step response characteristic.