Switching element for a valve drive of an internal combustion engine

Abstract

A switching element ( 1 ) for a valve drive of an internal combustion engine, preferably for shutting off valves, is provided, and includes an external part ( 2 ) in whose bore ( 3 ) an inner element ( 5 ) is axially movable. The external part ( 2 ) and the inner element ( 5 ) have at least a respective mutually aligned recess ( 7, 8 ) due to an axially spaced relative position obtained through a lost motion spring ( 6 ), and in one of the recesses, in the direction of the other recess, displaceable coupling means ( 9 ) are mutually applied in the relative position for coupling the inner element ( 5 ) with the external part ( 2 ). Two pistons ( 10 ) are provided as coupling means ( 9 ), which travel in the recess ( 8 ) formed as a radial bore of the inner element ( 5 ), and which diametrically oppose one another. The recess ( 7 ) of the external part ( 2 ) is formed as an annular groove ( 16 ) in the bore ( 3 ), and the pistons ( 10 ) at their underside ( 17 ) remote from the cam, starting from their radially external end faces ( 13 ), sectionally have a planar transverse surface ( 14 ) as contact region to a facing annular surface ( 15 ) of the annular groove ( 16 ), and the pistons ( 10 ) are guided with rotation securement ( 19 ) in the inner element ( 5 ). This provides a switching element ( 1 ) which has a simply constructed coupling mechanism, which produces only a small component loading.

1 . Switching element ( 1 ) for a valve drive of an internal combustion engine for shutting off valves, comprising an external part ( 2 ) with a bore ( 3 ) in which an inner element ( 5 ) is axially movable, the external part ( 2 ) and the inner element ( 5 ) having at least a respective mutually aligned recess ( 7 ,  8 ) due to an axially spaced relative position obtained by a lost motion spring ( 6 ) acting between the inner element and the external part, and in one of the recesses, in a direction of the other recess, a displaceable coupling mechanism ( 9 ) is provided for coupling the inner element ( 5 ) with the external part ( 2 ), wherein two pistons ( 10 ) are provided as the coupling mechanism ( 9 ), which travel in the recess ( 8 ) formed as a radial bore of the inner element ( 5 ), and which diametrically oppose one another, the recess ( 7 ) of the external part ( 2 ) being formed as an annular groove ( 16 ) in the bore ( 3 ), and the pistons ( 10 ) have an underside ( 17 ) and starting from a radially outer end face ( 13 ) of the pistons, sectionally have a planar transverse surface ( 14 ) as a contact region to a facing annular surface ( 15 ) of the annular groove ( 16 ), and the pistons ( 10 ) are guided by a rotation securement ( 19 ) in the inner element ( 5 ).  
   
   
       2 . Switching element according to  claim 1 , wherein the rotation securement ( 19 ) comprises an annular part which extends in an annular groove ( 20 ) on an external surface ( 4 ) of the inner element ( 5 ) and is arranged at a height such that the annular part engages under the planar transverse surface ( 14 ) of the piston ( 10 ).  
   
   
       3 . Switching element according to  claim 1 , wherein the recess ( 8 ) in the inner element ( 5 ) has a stop ( 12 ) for radially inner end faces of the pistons ( 10 ), and the stop ( 12 ) is positioned centrally.  
   
   
       4 . Switching element according to  claim 3 , wherein the recess ( 8 ) is formed as a through bore, and the stop ( 12 ) is formed as one of an annular part located in the through bore, or a component ( 21 ) that projects orthogonally into the through bore.  
   
   
       5 . Switching element according to  claim 1 , wherein the radially outer end face ( 13 ) of the piston ( 10 ), at least in an edge region ( 22 ) to the transverse surface ( 14 ), has a curvature corresponding to the bore ( 3 ) of the inner element ( 5 ).  
   
   
       6 . Switching element according to  claim 1 , wherein an end side ( 18 ) of the piston ( 10 ), connecting the transverse surface ( 14 ) with the underside ( 17 ), has a curvature correlating to the bore ( 3 ) of the inner element ( 5 ), or is formed with a roof-like bevel in a bottom surface thereof.  
   
   
       7 . Switching element according to  claim 1 , wherein the switching element ( 1 ) is produced as a cam follower in a tappet push rod drive.  
   
   
       8 . Switching element according to  claim 2 , wherein the recess ( 8 ) in the inner element ( 5 ) has a stop ( 12 ) for radially inner end faces of the pistons ( 10 ), and the stop ( 12 ) is positioned centrally.