Internal combustion engines require valves to aspirate and discharge gases. Engine designers require a high degree of flexibility to improve efficiency, reduce pollutants, and optimize the use of renewable fuels. Currently, the gas exchange valves of four-stroke engines are controlled through camshaft drives. Despite some complex additional mechanics, the flexibility of such camshaft-driven systems remains limited. An electrohydraulically actuated valve train -the FlexWork valve train - was developed that enables completely free adjustment of stroke and timing, while at the same time being robust and cost-effective. The valve train is the "respiratory organ" of combustion engines - it manages the aspiration of fresh air and the discharge of exhaust gases, referred to as gas exchange. Today, only mechanically driven camshafts are used in series production for this purpose and are often equipped with additional mechanisms, some of which are quite complex. This modifies a valve movement pattern given by the camshaft, which is not possible without an increase in friction. At the same time, flexibility is not provided 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.
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