Patent ID: 8215271

Claim:
The hydraulic unit for a cylinder head of an internal combustion engine with a hydraulically variable gas-exchange valve train, comprising: at least one drive-side master unit, at least one driven-side slave unit, at least one controllable hydraulic valve, at least one medium-pressure chamber, at least one high-pressure chamber that is arranged in a transmission sense between the associated drive-side master unit and the associated slave unit and that can be connected by the associated controllable hydraulic valve to the associated medium-pressure chamber, at least one low-pressure chamber that is used as a hydraulic medium reservoir and that is connected via a throttle point to the associated medium-pressure chamber, and a hydraulic housing with a bottom part of the housing, a middle part of the housing, and a top part of the housing, wherein the master unit, the slave unit, the high-pressure chamber, the hydraulic valve, and the medium-pressure chamber extend in the bottom part of the housing, the low-pressure chamber is constructed in the top part of the housing, and the throttle point extends through the middle part of the housing in a region of a hydraulic medium passage, the throttle point is formed by a valve body that can be displaced relative to the hydraulic medium passage and has through-flow cross sections of different sizes according to a position of the valve body, and the valve body blocks the throttle point in a first position corresponding to a hydraulic-flow from the medium-pressure chamber into the low-pressure chamber up to a throttling through-flow cross section and the valve body opens a low-throttle through-flow cross section in a second position corresponding to a flow of hydraulic medium from the low-pressure chamber into the medium-pressure chamber.