Self-adjusting hydraulic valve tappet

Claim 1

A self-adjusting hydraulic valve tappet arranged in a guide bore of a cylinder head of an internal combustion engine and being contacted at one end face of the valve tappet by a cam and bearing with a second end face against the end of a valve stem, the tappet comprising a cup-shaped housing comprised of a hollow cylindrical wall closed at one end by an end member against the outside of which the cam and a cylindrical guide sleeve concentric with the cylindrical wall and surrounded by an external oil reservoir and in which the play compensating element is guided for longitudinal movement and abuts at its end against the valve stem, characterized in that a polymeric inner element (4,31,32) defining the guide sleeve and forming the external oil reservoir (17) together with the cupshaped housing (1) comprises two concentric cylindrical walls (5,6), one of which abuts tightly against the bore wall of the hollow cylindrical wall (2) of the housing (1) and the second defines the guide sleeve for the self-adjusting play compensating element (7) and which are connected to each other by a radial flange (8,27) in a fluid-tight manner at least at their ends facing away from the end face (3) of the housing (1) and axially extending tube like channels (15,16) at the facing surfaces of the two cylindrical walls (5,6) at a respective circumferential area with the channel (15) arranged at the radially outer cylindrical wall (5) communicating freely at its end adjacent to the end face (3) of the housing with the external oil reservoir (17) and extending at its opposite end into a radial opening (18) aligned with a radial oil supply port (19) in the hollow cylindrical wall (2) of the housing (1) and channel (16) arranged at the guide sleeve extends at its end adjacent to end face (3) of the housing (1) into a radial opening (20) leading to the interior of the guide sleeve and communicating at its opposite end with the external oil reservoir (17).