The valve train is the “respiratory organ” of combustion engines: it manages the aspiration of fresh air and the discharge of exhaust gases, which is referred to as “gas exchange.” Today, only mechanically driven camshafts are used in series production for this purpose, often equipped with an additional mechanism, some of which are quite complex. This allows to modify a valve movement pattern given by the camshaft, which is not possible without an increase in friction. At the same time, flexibility is not given to the desired extent. What is in demand — among other things for adaptation to changing fuel properties — are fast valve movements even at low speeds, stroke adaptations and cylinder-selective widely variable valve timing. Patrik Soltic and his team at Empa’s Automotive Powertrain Technologies laboratory, together with hydraulics specialist Wolfgang Schneider, invented and developed an electrohydraulic valve train that is significantly more flexible than today’s series production technology. The valves are actuated hydraulically and controlled electrically via a solenoid coil. As soon as a control current flows, a specially...