Mercedes-benz Aktiengesellschaft

Andreas Rehberger

Ulrich Letsche

Frank Iberle

The invention relates to a freely activatable hydraulic valve control device for a stroke valve, which valve control device is arranged particularly in an internal-combustion engine. The stroke valve includes a valve stem and a first spring acting on the valve stem in the valve-closing direction as well as a second spring acting at least periodically on the valve stem in the valve-opening direction. The valve stem is connected at least to a control piston arranged in a working space and capable of being loaded on two sides with a working fluid. The pressure of the working fluid in the working space can be regulated via a pressure source together with a switching valve and a supply conduit. In order to improve further a hydraulic valve control device of the relevant generic type, it is provided that the prestressing force of the second spring is regulatable while the actuating arrangement is in operation and that, with the working fluid relieved of pressure in the working space and with the second spring contracted, the first spring holds the stroke valve in a closed position.

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Berglen, Germany

Andreas Rehberger