Valve drive of an internal combustion engine

Abstract

A valve drive ( 1, 1′ ) of an internal combustion engine with stroke-variable gas-exchange valve activation is provided. The valve drive includes a camshaft ( 2, 2′ ) with a carrier shaft ( 3 ) and a cam piece ( 4, 4′ ) that is arranged in a rotationally locked way on the carrier shaft and that can move between axial positions and that has a cam group of directly adjacent cams ( 14 a - c, 15 a - c ) with different lobes and a groove-shaped axial link ( 16, 16′ ) and an activation element ( 18, 19 ) that can be coupled in the axial link for shifting the cam piece on the carrier shaft. The cam piece is provided with a bearing journal ( 12, 13, or 12′ ) on which the camshaft is supported in the radial direction at a camshaft bearing point ( 9, 10, or 9′ ) of the internal combustion engine. Here, the axial link is constructed overlapping with the camshaft bearing point on the bearing journal in the axial direction, and the activation element runs in the camshaft bearing point.

1 . A valve drive of an internal combustion engine with stroke-variable gas-exchange valve activation, comprising a camshaft with a carrier shaft and a cam piece that is arranged in a rotationally locked manner on the carrier shaft and is moveable between axial positions and that has a cam group of directly adjacent cams with different lobes and a groove-shaped axial link, an activation element that is coupleable in the axial link for shifting the cam piece on the carrier shaft, the cam piece is provided with a bearing journal on which the camshaft is supported in a radial direction at a camshaft bearing point of the internal combustion engine, the axial link is constructed overlapping with the camshaft bearing point on the bearing journal in an axial direction, and the activation element runs in the camshaft bearing point. 
     
     
         2 . The valve drive according to  claim 1 , wherein the bearing journal with the camshaft bearing point forms a sliding bearing, the bearing journal has sliding surface sections on both sides of the axial link in the axial direction. 
     
     
         3 . The valve drive according to  claim 1 , wherein a bearing diameter of the bearing journal is larger than a surrounding diameter of the cam lying closest to the bearing journal, and the cam lying closet to the bearing journal and the camshaft bearing point overlap in the axial direction in one of the axial positions of the cam piece. 
     
     
         4 . The valve drive according to  claim 1 , wherein the cam piece has two of the bearing journals that are constructed on axial end sections thereof and two cam groups are arranged between the bearing journals. 
     
     
         5 . The valve drive according to  claim 1 , wherein the cam piece has two of the cam groups constructed on axial end sections thereof and the bearing journal consists of a single bearing journal arranged between the cam groups. 
     
     
         6 . The valve drive according to  claim 1 , wherein the cam piece includes a single one of the axial links that is constructed in a bidirectional way with two connecting paths running in an opposite sense in the axial direction. 
     
     
         7 . The valve drive according to  claim 6 , wherein the two connecting paths are arranged one next to the other in a peripheral direction of the bearing journal and cross one another in a middle area. 
     
     
         8 . The valve drive according to  claim 6 , wherein the two connecting paths are arranged one behind the other in a peripheral direction of the bearing journal, and each starting point of one of the connecting paths is adjacent to an end point of the other of the connecting paths. 
     
     
         9 . The valve drive according to  claim 1 , wherein there are three directly adjacent cams for each of the cam groups and two activation elements that are coupleable alternately in the same axial link. 
     
     
         10 . The valve drive according to  claim 9 , wherein one of the three cams is free of lobes.