Variable valve actuation apparatus, system, and method

Abstract

A variable valve actuation system is disclosed. In one form a rocker is disclosed coupled with a valve stem at one end and a cam follower at the other end. The rocker is operable to pivot about a fixed axis. The cam follower is operable to be pivotally coupled with the rocker at one end of the cam follower. The cam follower includes a lower roller and an upper roller at its other end, each operable to engage cam lobes on separate cam shafts. In one form the cam follower includes a lower roller operable to follow a cam lobe on a lower cam shaft and an upper roller operable to follow a cam lobe on an upper cam shaft. The upper cam shaft and the lower cam shaft can have variable lobes. A spring can be used to bias the cam follower on the rocker.

1 . An apparatus comprising:
 a cam follower operable to be pivotally coupled with a valve rocker arm and having a first rotatable member operable to be engaged with a first cam lobe substantially throughout a revolution of a cam shaft and a second rotatable member operable to be disengaged from a second cam lobe through a portion of the revolution.   
     
     
         2 . The apparatus of  claim 1 , wherein the cam follower includes one end that is pivotally coupled with the valve rocker arm and a second end having the first rotatable member and the second rotatable member. 
     
     
         3 . The apparatus of  claim 2 , wherein the first rotatable member is operable to be coupled with a first cam shaft, and the second rotatable member is operable to be coupled with a second cam shaft. 
     
     
         4 . The apparatus of  claim 2 , which further includes an energy member operable to bias the cam follower such that the second rotatable member is disengaged from the second cam lobe. 
     
     
         5 . The apparatus of  claim 4 , wherein the energy member is a spring. 
     
     
         6 . The apparatus of  claim 2 , which further includes the first cam shaft having a variable first lobe that is operable to engage the first rotatable member and the second cam shaft having a variable second lobe that is operable to engage the second rotatable member. 
     
     
         7 . An apparatus comprising:
 a cam follower having a pivot aperture operable to be pivotally coupled with a rocker arm, the cam follower having an end that includes a first cam lobe contact member operable to contact a first cam lobe and a second cam lobe contact member operable to contact a second cam lobe.   
     
     
         8 . The apparatus of  claim 7 , wherein the first cam lobe contact member and the second cam lobe contact member include portions located in a plane perpendicular to a pivotal axis of the cam follower. 
     
     
         9 . The apparatus of  claim 7 , wherein the first cam lobe contact member is a roller coupled to the cam follower through a bearing. 
     
     
         10 . The apparatus of  claim 7 , wherein the cam follower includes a load bearing portion structured to receive a force from an energy member. 
     
     
         11 . The apparatus of  claim 10 , wherein the energy member is a spring. 
     
     
         12 . The apparatus of  claim 11 , wherein the spring is selected from the group consisting of a helical coil spring and a leaf spring. 
     
     
         13 . The apparatus of  claim 10 , wherein the energy member operable to be coupled to a relatively fixed location of an internal combustion engine. 
     
     
         14 . The apparatus of  claim 7 , wherein the first cam lobe contact member is operable to contact a first cam shaft and the second cam lobe contact member is operable to contact a second cam shaft. 
     
     
         15 . The apparatus of  claim 8 , wherein the first cam shaft includes an independently variable cam lobe, the first cam lobe contact member operable to disengaged from the independently variable cam lobe over a portion of a revolution of the first cam shaft. 
     
     
         16 . An apparatus comprising:
 a rocker arm operable to be used in a variable valve actuation engine;   a first cam shaft and a second cam shaft; and   means for engaging a lobe on the first cam shaft and a lobe on the second cam shaft.   
     
     
         17 . A method comprising:
 rotating a first cam shaft having a first lobe and a second cam shaft having a second lobe;   periodically engaging the first lobe with a first member of a cam follower;   substantially engaging the second lobe with a second member of the cam follower;   pivoting the cam follower about a rocker; and   moving the rocker to actuate a valve.   
     
     
         18 . The method of  claim 17 , which further includes biasing the cam follower with an energy device. 
     
     
         19 . The method of  claim 17 , wherein the periodically engaging and the substantially engaging occur on one side of the pivoting the cam follower.