Phaser-actuated continuously variable valve actuation system with lost motion capability

Abstract

A system for continuously varying actuation of a valve in an internal combustion engine including a first cam for opening the valve, a second cam for closing the valve, and an oscillating rocker arm continuously engaging each of the first cam, the second cam, and the valvetrain, with the aid of a lost motion spring. The cams are disposed on first and second camshafts that are geared together. The first camshaft gear is driven by the engine crankshaft and thus is phase-invariant. The second camshaft gear is rotationally mounted on the second camshaft and supports the stator of a camshaft phaser. The phaser rotor is mounted to the second camshaft. Varying the rotor position varies the phase of the second cam and thus varies lift and closing timing of the valve. The system is useful in improving the performance of both spark-ignited and compression-ignited engines.

1 . A system for variably actuating a combustion valve in a valvetrain in an internal combustion engine, comprising:
 a) a first cam for opening said valve, said first cam having a first base circle portion and a first working portion;   b) a second cam for closing said valve, said second cam having a second base circle portion and a second working portion;   c) an oscillating rocker arm having first, second, and third working elements and being disposed among and continuously engaging each of said first cam in contact with said first working element, said second cam in contact with said second working element, and said valvetrain in contact with said third working element; and   d) a phasing device for varying the phase of at least one of said first and second cam lobes to vary actuation of said combustion valve.   
   
   
       2 . A system in accordance with  claim 1  further comprising a lost motion spring disposed against said oscillating rocker arm for maintaining said continuous engagement. 
   
   
       3 . A system in accordance with  claim 1  wherein said third working element includes a cam surface for engaging said valvetrain. 
   
   
       4 . A system in accordance with  claim 3  wherein said cam surface includes a cam surface base circle portion and a cam surface working portion. 
   
   
       5 . A system in accordance with  claim 1  wherein said second working portion must be engaged with said oscillating rocker arm to permit said first working portion to open said valve. 
   
   
       6 . A system in accordance with  claim 1  wherein said first working portion must be engaged with said oscillating rocker arm to permit said second base circle portion to close said valve. 
   
   
       7 . A system in accordance with  claim 1  wherein the phase of at least one of said first and second cams is sufficiently adjustable to prevent said first working portion and said second working portion from being engaged simultaneously with their respective first and second working elements, thus preventing any valve activation during operation of said engine. 
   
   
       8 . A system in accordance with  claim 1  wherein said phasing device comprises:
 a) a first camshaft supportive of said first cam;   b) a second camshaft supportive of said second cam; and   c) a camshaft phaser disposed on at least one of said first and second camshafts.   
   
   
       9 . A system in accordance with  claim 8 ,
 wherein said first camshaft is operatively connected to a crankshaft of said engine to rotate at one-half the crankshaft rotational speed, and   wherein said camshaft phaser is disposed on said second camshaft to variably alter the phase relationship of said second cam to said first cam.   
   
   
       10 . A system in accordance with  claim 9 , further comprising:
 a) a first gear fixed to said first camshaft; and   b) a second gear rotationally disposed on said second camshaft and meshed with said first gear,   wherein a driving member of said camshaft phaser is connected to said second gear for rotation therewith such that said driving member turns synchronously with said first camshaft and said crankshaft, and   wherein a driven member of said camshaft phaser is connected to said second camshaft such that changing the phase relationship of said driven member to driving member causes a phase change between said first and second camshafts.   
   
   
       11 . A system in accordance with  claim 1  wherein said oscillating rocker arm oscillates about a floating axis. 
   
   
       12 . A system in accordance with  claim 11  wherein said floating axis is coincident with an axis of said second working element. 
   
   
       13 . A system in accordance with  claim 1  wherein said oscillating rocker arm oscillates about a fixed axis. 
   
   
       14 . A system in accordance with  claim 13  further comprising;
 a) an intermediate shaft extending through said oscillating rocker arm; and   b) a fixed shaft extending through said oscillating rocker arm and including said fixed axis.   
   
   
       15 . A system in accordance with  claim 1  wherein said first and second working elements are rollers disposed in said oscillating rocker arm. 
   
   
       16 . A system in accordance with  claim 1 ,
 wherein said internal combustion engine includes a second valvetrain and combustion valve operative in parallel with said claimed valvetrain and combustion valve, and   wherein said system further comprises a parallel-operating first cam, second cam, and oscillating rocker arm operatively linked to said claimed first cam, second cam, and oscillating rocker arm, respectively.   
   
   
       17 . A system in accordance with  claim 1 ,
 wherein said valvetrain includes a poppet valve seat, a poppet valve head and stem, a valve return spring, and a roller finger follower operatively disposed against said valve stem, and   wherein said third working element is engaged with said roller finger follower.   
   
   
       18 . A system in accordance with  claim 1  wherein said first cam and said second cam are rotational in opposite directions. 
   
   
       19 . A system in accordance with  claim 1  wherein said first cam lobe and said second cam are rotational in the same direction. 
   
   
       20 . An internal combustion engine comprising:
 a system for variably actuating a combustion valve in a valvetrain in said engine, wherein said system includes,   a first cam for opening said valve, said first cam having a first base circle portion and a first working portion,   a second cam for closing said valve, said second cam having a second base circle portion and a second working portion,   an oscillating rocker arm having first, second, and third working elements and being disposed among and continuously engaging each of said first cam in contact with said first working element, said second cam in contact with said second working element, and said valvetrain in contact with said third working element, and   a phasing device for varying the phase of at least one of said first and second cams to vary actuation of said combustion valve.   
   
   
       21 . An internal combustion engine in accordance with  claim 20  wherein said engine is selected from the group consisting of spark-ignited and compression-ignited. 
   
   
       22 . An internal combustion engine in accordance with  claim 21  wherein said spark-ignited engine is operated in a mode selected from the group consisting of Continuous Variable Valve Lift and Continuous Variable Valve Duration. 
   
   
       23 . An internal combustion engine in accordance with  claim 21  wherein said compression-ignited engine is operated in a Continuous Variable Valve Duration mode.