Variable valve actuation system having a crank-based actuation transmission

Abstract

A variable valve actuation system having a crank-based eccentric transmission driven by an electric motor to control valve lift, duration, and phasing in the cylinder head of an internal combustion engine. A rocker sub-assembly for each valve is pivotably disposed on a pivot shaft between the camshaft and the roller finger follower roller. A primary control crankshaft includes the pivot shaft and is itself rotated about its axis by a connecting rod driven by a motorized secondary crank mechanism to displace the rocker sub-assembly pivot shaft along an arcuate path to change the angular relationship of the rocker sub-assembly to the camshaft, thus changing the valve opening and closing timing and valve lift.

1 . A variable valve actuation system for inclusion in an internal combustion engine, comprising:
 a) a variable valve actuation sub-assembly disposed between a camshaft and a roller finger follower to variably actuate an associated engine combustion valve to vary the timing of valve opening, timing of valve closing, and amplitude of valve lift; and   b) a crank-based transmission operatively attached to said variable valve actuation sub-assembly for selective actuation thereof.   
   
   
       2 . A system in accordance with  claim 1  wherein said variable valve actuation sub-assembly comprises:
 a) a pivot shaft having a first axis disposed parallel to an axis of rotation of said camshaft defined as a second axis;   b) a rocker sub-assembly pivotably disposed on said pivot shaft for rotation about said first axis, said rocker sub-assembly having a follower for following a lobe of said camshaft and having an output cam for engaging said roller finger follower; and   c) a primary crank mechanism pivotably supportive of said rocker sub-assembly and said pivot shaft for varying the distance of said first axis from said second axis to vary the action of said output cam upon said one of said roller finger followers to vary said timing and lift of said associated valve, said primary crank mechanism being pivotable about a third axis outside of said pivot shaft.   
   
   
       3 . A system in accordance with  claim 1  wherein said primary crank mechanism further comprises:
 a) a control shaft segment for said rocker sub-assembly wherein said third axis is the axis of said control shaft segment; and   c) at least one rocker control arm connected between said pivot shaft and said rocker control shaft segment.   
   
   
       4 . A system in accordance with  claim 3  wherein said crank-based transmission comprises:
 a) a connecting rod pivotably connected at a first end thereof to said rocker control arm and having a bearing journal formed at a second end thereof; and   b) a secondary crank mechanism including a circular lobe rotatably disposed in said bearing journal and a transmission control shaft disposed eccentrically on said circular lobe, said transmission control shaft being mounted for rotation on said engine for rotating said pivot shaft, said rocker control arm, and said rocker control shaft segment about said third axis.   
   
   
       5 . A system in accordance with  claim 4  further comprising an electric motor coupled to said transmission control shaft for rotation thereof to variably position said rocker sub-assembly with respect to said camshaft, via said circular lobe, said connecting rod, and said rocker control arm. 
   
   
       6 . A system in accordance with  claim 3  further comprising a bias spring disposed between said rocker sub-assembly and said rocker control arm for maintaining contact of said roller with said cam lobe. 
   
   
       7 . A system in accordance with  claim 1 , wherein said engine includes a plurality of cylinders, valves, cam lobes, and roller finger followers defining an inline bank of cylinders, and
 wherein a variable valve actuation sub-assembly and a crank-based transmission is associated with each of said plurality of cylinders.   
   
   
       8 . A variable valve actuation system for use in an internal combustion engine having a plurality of inline cylinders, the system being included between a camshaft and a plurality of roller finger followers for variably actuating a plurality of associated engine combustion valves to vary the timing of valve opening, timing of valve closing, and amplitude of valve lift, the system comprising for each of said plurality of inline cylinders a variable valve actuation sub-assembly and a crank-based variable valve actuation transmission operatively attached to said variable valve actuation subassembly for selective actuation thereof. 
   
   
       9 . An internal combustion engine, comprising:
 a) a camshaft;   b) a valvetrain including a plurality of combustion valves;   c) a plurality of roller finger followers disposed between said camshaft and said combustion valvetrain; and   d) a variable valve actuation system disposed between said camshaft and said plurality of roller finger followers, including a variable valve actuation sub-assembly and a crank-based variable valve actuation transmission operatively attached to said variable valve actuation sub-assembly for selective positioning of said variable valve actuation sub-assembly with respect to said camshaft.