Patent ID: 7401584

Claim:
A switchable cam follower which serves to transmit a cam stroke in a variable manner from a cam to valve timing mechanism elements of an internal combustion engine and has essentially the following features: the cam follower comprises substantially a cylindrical inner part and a cylindrical outer part which can be displaced into one another in the direction of their longitudinal axes and can be locked and unlocked in a relative position by means of coupling means which are actuated by pressure-modulated hydraulic medium, and also comprises at least one spring means which is arranged between the inner part and the outer part, the inner part has a run-on surface for the cam at one end side and is radially guided in an inner wall of the outer part by way of an outer circumferential surface, the outer part has an outer cylindrical circumferential surface, by way of which the cam follower is guided in a housing hole of the internal combustion engine in a longitudinal movable manner, and an outer end face facing away from the cam, as a contact face for valve timing mechanism elements which are operatively connected to the cam follower, wherein the outer circumferential surface of the outer part has substantially identical diameters in the region of the end face which faces the valve timing mechanism element and in the region of an opening which is oriented toward the inner part, and wherein the spring means is arranged within the outer part, wherein the coupler means comprise at least one piston which is mounted with a cylindrical section in a coupling means hole of the inner part so as to be displaceable counter to the force of a spring means and which has a partially cylindrical section with a longitudinal surface at an opening of the coupling means hole which is oriented toward the outer part, there is an annular groove in the inner wall of the outer part, into which annular groove the piston reaches with the partially cylindrical section in the locked state of the cam follower, the longitudinal surface of the partially cylindrical section being oriented constantly substantially parallel to an axial shoulder of the annular groove and facing away from the run-on surface for the cam, by means of an antirotation safeguard element located in the inner part, and being in force-transmitting contact with this axial shoulder in the event of the intended transmission of movement between the inner part and the outer part of the cam follower.