Patent ID: 7325523

Claim:
A valve timing gear of an internal combustion engine comprising hydraulic valve clearance adjusting elements, in which each of the elements comprises a rotationally symmetrical housing, which is guided so that it is longitudinally displaceable in a seat in the engine and at one axial end of the element is acted upon by a cam of a camshaft, the contact surface of the cam having dimensional tolerances which give rise to a base circle eccentricity in a peripheral direction and which are determined by positive and negative dimensional deviations in the radial dimension of the contact surface, and the element comprising a piston, axially displaceable in the housing, and being non-positively connected by way of this piston or the housing, either directly or via further valve train components provided with contact surfaces, to an engine gas exchange valve, a control valve, which has a closing member and a valve seat for this formed on the piston, being arranged axially between the housing and the piston, wherein a reverse-spring element is used as valve clearance adjusting element, that is to say an element the control valve of which comprises a control valve spring, which is supported by one end on the piston and by the other end on the closing member, and in that the dimensional tolerances of the contact surface of the cam in total exceed 25 μm.