Patent ID: 7617806
Filing Date: 2009-11-17
Classification: F01L

Abstract:
1. A valve drive of an internal combustion engine for actuating a gas-exchange valve, whose movement follows a lift of a cam, comprising a hydraulic force-applying device having a lift which is superimposed on the lift of the cam and which is independent of the lift of the cam, the force-applying device including a piston that can move relative to a housing of the force-applying device from a first end position in which the gas-exchange valve is closed to a second end position in which the gas-exchange is opened through a time variable feed of a pressure-adjustable hydraulic medium from a hydraulic medium line into a pressure chamber formed by the piston and the housing, the pressure chamber is connected to the hydraulic medium line via blocking means arranged in the housing and opening into the pressure chamber and also via at least one separate passage in the housing leading from the hydraulic medium line to the pressure chamber, and the at least one passage is at least partially blocked by the piston in the first end position due to overlapping by an outer casing surface of the piston.