The Empa team has built the valve train on a gasoline engine and is now exploring the possibilities offered by this new technology. One variant of load control is cylinder deactivation. This means that, in the partial load range, individual cylinders are operated at high load, while others are switched off completely by keeping all valves closed. However, the sudden transition from an operation with all cylinders to an operation with some cylinders shut down would result in undesirable torque peaks, so the transition must be smooth. In systems on the market today without a fully variable valve timing, such cylinder deactivation is triggered by ignition interventions that greatly reduce efficiency. With Empa’s fully variable valve control system individual cylinders can be shut down without any loss of efficiency.
Just as it is possible to shut down cylinders completely, it is also possible to fire them less frequently. This turns a four-stroke operation into an eight- or twelve-stroke operation. Compared with a throttled four-stroke engine, such an engine operates much more efficiently.