Aktiv ventilstyrning
To achieve an optimal combustion, an even air/fuel ratio in the combustion chamber is required. An optimal combustion leads to reduced amount of emissions due to a more complete combustion, which is an important matter because of the sharpened environmental laws. This can be attained, among other things, by applying entirely variable cam times. To optimize the engines efficiency and its emissions at all workloads and speeds, an active valve control can be applied. This means that the intake and exhaust-valves can be opened and closed at any time, independent of the crankshaft position. The aim for this project was to design a prototype where a valve thought for a camless engine can be controlled. The traditional valve was used and the importance was to study and develop control system and damping of this part. The work resulted in an electromagnetic system where two electromagnets together operates and drives a permanent magnet, which is in direct connection to the valve. The Permanent magnet and thus the valve is attracted and repelled at the same time by the electromagnets, which leads to the valve being either opened or closed. To accomplish this, a control unit was prepared to generate different operating conditions. The movement and damping of the valve is enabled trough an H-bridge, which is an electronic circuit that allows the change in current direction, to make it possible to achieve the quick polarity switch that is desired for the electromagnets. The results of the measurements were close to the target set. Apart from the desired frequency, we could find that damping trough polarity change was possible and also that a stabile system could be achieved with reasonable power consumption.