Patent ID: 7237520

Claim:
A hydraulic valve-lash-adjusting element (HVA) for the valve train of an internal combustion engine, wherein: a housing ( 1 ) has a blind bore ( 2 ) in which a piston ( 3 ) is guided with sealing clearance and is in pressure contact with a valve-actuating element ( 6 ) and its cam; the piston ( 3 ), together with the blind bore ( 2 ), defines a high-pressure space ( 4 ) while a low-pressure space ( 5 ) is located above the piston ( 3 ); the pressure spaces ( 4 , 5 ) are connected by at least one central axial bore in the piston ( 3 ), this axial bore being controlled by a control valve arranged in the piston ( 3 ), wherein the control valve is designed as an exchange valve ( 11 ), with a valve body ( 12 ) which is guided in a smooth-running manner in the interior of the piston ( 3 ), serves to control an upper and a lower central axial bore ( 14 , 15 ) and the closing movement in both directions of which is the relative movement of the piston ( 3 ) in relation to the valve body ( 12 ), which is virtually at a standstill because of its mass moment of inertia, the upper central axial bore ( 14 ) can be closed by a downwards movement of the piston ( 3 ) and the lower central axial bore ( 15 ) can be closed by the upwards movement of the said piston, the downwards movement of the piston ( 3 ) takes place by means of the cam and its upwards movement takes place by means of a compression spring ( 7 ) arranged in the high-pressure space ( 4 ), the valve body ( 12 ) is of circular-cylindrical design and is guided in an axial central bore ( 13 ) which connects the two central axial bores ( 14 , 15 ), by means of interaction of preferably flat sealing surfaces ( 18 , 19 ) of the end sides ( 16 , 17 ) of the valve body ( 12 ) with flat sealing surfaces ( 20 , 21 ) of the shoulders ( 22 , 23 ) of the piston ( 3 ), the oil flow through the central axial bores ( 14 , 15 ) or between the pressure spaces ( 4 , 5 ) can be controlled and the piston ( 3 ) has an upper part ( 8 ) and a lower part ( 9 ) which are both of identical design and, after the valve body ( 12 ) is installed, are connected in a mirror-inverted and pressure and pressure-tight manner.