Patent ID: 7640906

Claim:
A hydraulic valve lash adjuster with idle stroke function for a valve train of an internal combustion engine, said hydraulic valve lash adjuster comprising a piston that is guided for displacement in a piston housing and elastically supported against said housing, said piston comprising a low pressure chamber that communicates via an axial opening in a piston bottom with a high pressure chamber defined by the piston housing and the piston, and further comprising a control valve acting between said pressure chambers, said control valve comprising a valve closing body that can be brought to bear sealingly against a valve seat that surrounds the axial opening on a piston body undersurface and is received in an element that limits a closing body stroke, and said control valve further comprising a control valve spring that loads the valve closing body in opening direction, and an idle stroke being produced during an axial collapsing movement between the piston and the piston housing during which said valve closing body is hydraulically loaded in closing direction against the action of the control valve spring by a pressure build-up in the high pressure chamber, wherein a retarded pressure build-up can be obtained through a flow control device arranged on a high pressure chamber-side and comprising a flow control element configured as a disk and a medium pressure chamber that extends between the flow control element and the axial opening.