Valve drive for an internal combustion engine
View Patent ↗A drive valve for an internal combustion engine comprising a variable hub profile for a valve having a lever supported on a variable support point by means of a switchable support element which provides possibilities for influencing the hub profile and alternatively and cumulatively, the cam is axially displaced such that various cam paths are active on the lever.
1. A valve drive for an internal combustion engine having a lever which opens and closes a valve and which can be pivoted with respect to a support point by a cam of a camshaft, with
a) the cam
being movable into a first axial position and into a second axial position,
having a first cam track which acts in the first axial position and a second cam track which acts in the second axial position, and
b) the support point is variable to vary the lifting movement of the valve, the support point is formed by a support element which is switchable with a first switching sition in which the support point is fixed with a second econd switchin position in which the support point is movable during a rotation of the camshaft, and
c) the second cam track has a smaller lift than the first cam track and a idle stroke of the support element is dimensioned such that, during a rotation about the entire second cam track, the support point is moved by the idle stroke in one direction and then back again, while the valve remains at least unmoved.
2. The valve drive of claim 1 , wherein the support element has a valve play compensating element.
3. The valve drive of claim 1 wherein a control device is provided which is connected to actuators which bring about a movement of the cam into the first and second axial positions and a movement of the support element into the first and second switching positions, with the control device being designed such that
in a first operating phase, the support element is arranged in the first switching position and the cam is arranged in the first axial position,
in a second operating phase, the support element is arranged in the first switching position and the cam is arranged in the second axial position, and
in a third operating phase, the support element is arranged in the second switching position and the cam is arranged in the second axial position.
4. The valve drive of claim 1 , wherein two cams with in each case two cam tracks can be moved together.
5. The valve drive of claim 1 , wherein the support point can be moved less than five millimeters in the second switching position.