Discrete mode variable valve gear

Abstract

A valve lifter is activated selectively by one of a plurality of cams, either via displaceable rollers or via tappets having rotatable grooves on top, to provide discrete or stepwise multimode operation and deactivation. The hydraulic control is only an option since the pure mechanical control is adequate. Easy to retrofit into existing engines.

1 . A valve-operating system for an internal combustion engine, comprising: 
 a valve lifter moved in unison with a valve mounted in an engine body;    a plurality of cams, each one for providing a specific operational mode to the valve, with at least one cam, of said plurality of cams, being not in direct engagement to said valve lifter;    a roller for engaging said at least one cam with said valve lifter;    a displaceable engaging member mounted slidably or pivotally or in other way on said engine, holding said roller and providing the necessary reaction to said roller;    said displaceable engaging member has an activation position where said roller engages said at least one cam and said valve lifter transferring camming action from said at least one cam to said valve lifter, and a deactivation position where said valve lifter is disengaged from said at least one cam;    so that said valve lifter can be activated from different cams, depending on the position of the relevant engaging members.    
   
   
       2 . As in  claim 1  wherein said roller abuts along a surface of said displaceable engaging member.  
   
   
       3 . As in  claim 1  wherein said roller is supported on a rocker pivotally mounted on said displaceable engaging member.  
   
   
       4 . As in  claim 1  wherein said valve lifter is a bucket lifter.  
   
   
       5 . As in  claim 1  wherein the engaging member has more than one activation positions for providing additional valve lift profiles.  
   
   
       6 . As in  claim 1  wherein said valve lifter activates more than one valves.  
   
   
       7 . A tappet cam follower reciprocating along a tappet guide of an engine, 
 the tappet cam follower is angularly displaceable,    the tappet cam follower cooperates with a set of cams mounted on a camshaft of said engine, said set of cams comprises at least one cam, characterized in that:    the close to the camshaft side of the tappet cam follower is configured such that at a first angular position of the tappet cam follower it provides space to a cam, of the set of cams, to rotate without actuating the tappet cam follower, while at a second angular position of the tappet cam follower the same cam actuates the tappet cam follower.    
   
   
       8 . A tappet cam follower reciprocating along a tappet guide of an engine, the tappet cam follower being actuated by at least one cam, of a plurality of cams mounted on a camshaft of said engine, the tappet cam follower is angularly displaceable about the axis of said tappet guide, characterized in that the tappet cam follower is configured such that it selectively engages and disengages at least one cam, of the plurality of cams, according its angular displacement.  
   
   
       9 . As in  claim 7 , characterized in that said close to the camshaft side of the tappet cam follower comprises grooves or gaps to allow, at an angular position of the tappet cam follower, one or more of the cams of the set of cams to pass through and thereby be disengaged from the tappet cam follower.  
   
   
       10 . As in  claim 7 , characterized in that said set of cams comprises at least two cams of substantially the same profile, said at least two cams are simultaneously engaged and disengaged to provide substantially uninterruptible abutment between the camshaft and the tappet cam follower despite the gaps on the tappet cam follower surface.  
   
   
       11 . As in  claim 7 , characterized in that the tappet cam follower can be locked at additional angular positions in order to engage and disengage additional cams or group of cams of the set of cams and thereby to provide further modes of operation.  
   
   
       12 . As in  claim 7 , characterized in that the set of cams comprises high lift cams and low lift cams or no lift cams.  
   
   
       13 . As in  claim 7 , characterized in that the tappet cam follower comprises hydraulic lash adjuster.