Internal combustion engine having electrohydraulic valve control and method for operating said internal combustion engine

摘要

An internal combustion engine (4) having an electrohydraulic valve control (1) for the variable lift drive of a gas exchange valve (3) is provided. The hydraulic valve (15) is actuated by an electronic control module (16) such that a gas exchange valve stroke (19) required for a charge change is adjusted during the cold start phase of the internal combustion engine (4) within a minimum stroke height (h-min) and a maximum closing time (α-max). A method for operating the internal combustion engine (4) is also provided.

主权项

1. An internal combustion engine having an electrohydraulic valve control for a variable-stroke driving of a gas exchange valve upon which a spring force is applied in a closing direction, comprising a camshaft and a hydraulic system arranged to act as a drive between the camshaft and the gas exchange valve, said hydraulic system being connected to a hydraulic medium supply of the internal combustion engine, and having the following:
a first hydraulic piston driven by a cam of the camshaft, and a second hydraulic piston that drives the gas exchange valve in an opening direction, a pressure chamber delimited by the first hydraulic piston and by the second hydraulic piston, having a modifiable volume and a control channel that connects the pressure chamber to a pressure relief chamber, an electrically controlled hydraulic valve, situated in the control channel, that permits a flow of hydraulic medium through the control channel in an open position of the hydraulic valve, and that blocks said flow in a closed position of the hydraulic valve,and comprising an electronic control module for controlling the hydraulic valve as a function of operating parameters of the internal combustion engine, the electronic control module is configured to control the hydraulic valve as a function of at least one of an operating hydraulic medium temperature, viscosity, or an operating pressure in the hydraulic medium supply, such that during an engine operating phase that includes a starting process of the internal combustion engine and includes one or immediately successive rotations of the camshaft, only a prespecified partial volume of the pressure chamber is filled with hydraulic medium, and the hydraulic valve is in the closed position at least during each overall lift phase of the cam, and during a further engine operating phase following the engine operating phase, which includes immediately successive rotations of the camshaft, the pressure chamber is at least almost completely refilled with hydraulic medium before each lift phase of the cam.