Patent ID: 8347839

Claim:
An internal combustion engine having a variable-lift electrohydraulic valve actuation comprising: a crankcase and a cylinder head; a camshaft comprising a cam and a cam tappet for taking up a cam lift, the camshaft and the cam tappet being arranged outside the cylinder head either in the crankcase or in a camshaft housing mounted on the crankcase; a rocker arm and a gas exchange valve actuated by the rocker arm, the rocker arm and the gas exchange valve being arranged in the cylinder head; a master piston actuated by the cam tappet and a slave piston which actuates the rocker arm, the master piston and the slave piston defining a variable-volume hydraulic pressure chamber; an electrically operable hydraulic valve and a hydraulic pressure-relief chamber that can be connected through the hydraulic valve to the pressure chamber, the master piston, the slave piston, the hydraulic valve, the pressure chamber and the pressure-relief chamber together with a common hydraulic housing are pre-assembled separate from the crankcase and the cylinder head as an assembled hydraulic unit discrete from the internal combustion engine, the hydraulic unit is installed in the crankcase or mounted outside of the cylinder head on the camshaft housing and connected to a hydraulic medium circulation of the internal combustion engine.