Continuously variable valve timing, lift and duration for internal combustion engine

Abstract

Continuously variable valve timing, lift and duration in an engine are achieved by altering the location of the pivot of the rocker arm and by using a variable rocker arm assembly. The pivot of the rocker arm assembly alters when a variable valve lift disc rotates. The variable rocker arm assembly is composed of two sets of arms. One end of both arms rotates around the pivot and the other ends of both arms lay over on each other and are separated by a spring. The separation gap is used to compensate the amount of valve lift. When the separation gap between the two arms changes due to the pivot shaft position change, valve lift changes accordingly. The variable lift disc is used to alter the position of the rocker arm pivot and it has engaging teeth that mate with a helical gear. The rocker arm shaft is mounted on the variable lift disc, when the disc rotates, it alters the rocker arm pivot position. The disc rotates under the longitudinal movement of the helical gear controlled by the hydraulic oil pressure from lubricant. The longitudinal travel of the helical gear is directly related to the engine speed and the hydraulic pressure. Under higher engine RPM, higher hydraulic pressure pushes helical gear longitudinally and rotates the variable lift disc, thus achieve higher valve lift by eliminating the separation gap between two arms. Under low engine RPM or low hydraulic oil pressure, a spring attached to the helical gear assembly forces the helical gear subsequently the pivot of rocker arm back to its original position. Therefore, the separation gap in the variable rocker arm assembly increases, consequently the valve lift decreases. The valve lift, depending on engine speed, varies continuously from zero to maximum lift.

I claim:  
     
         1 . A continuously variable valve timing, lift and duration system for an internal combustion engine comprising a variable rocker arm assembly, a variable lift disc, and a driving device.  
     
     
         2 . The system as claimed in  claim 1  wherein the said rocker arm assembly is end pivoted and has two sets of arms. Both arms have a pivot rocker shaft at one end. The other ends of the arms lay over on each other and are separated by a spring.  
     
     
         3 . The system as claimed in  claim 1  wherein the said rocker arm is center pivoted and has two sets of arms. Both arms share a pivot rocker shaft. The other ends of the arms lay over on each other and separated by a spring.  
     
     
         4 . The system as claimed in  claim 1  wherein the pivot of rocker arm is mounted to the said variable lift discs. The said disc is toothed on inside diameter. The position of the said rocker arm pivot alters when the said disc rotates.  
     
     
         5 . The system as claimed in  claim 1  wherein the said pivot point of rocker arm is mounted to the said variable lift discs. The said disc has engaging gear teeth on outside diameter. The position of the said rocker arm pivot alters when the said disc rotates.  
     
     
         6 . The system as claimed in  claim 1  wherein the said variable lift disc is a section of a circular plate. It alters the rocker arm pivot position when rotates.  
     
     
         7 . The system as claimed in  claim 1  wherein the said variable lift disc is an eccentric shaft. The said shaft alters the rocker arm pivot potion when it rotates.  
     
     
         8 . The system as claimed in  claim 1  wherein the said driving device comprises a gear, a spring, and a hydraulic system. The said gear makes the said variable lift disc rotate when the said gear moving by the said hydraulic system. The said spring pushes the said helical gear back towards its original position when the said pressure of hydraulic system drops. And the pressure of said hydraulic system is a function of engine speed.  
     
     
         9 . The system as claimed in  claim 1  wherein the said driving device is a stepping motor. The motor drives the variable disc and alters the rocker arm pivot position, thus alters the valve lift.  
     
     
         10 . The system as claimed in  claim 8  wherein the said spring is replaced with a hydraulic unit. The pressure difference of said hydraulic system drives the gear and rotates the variable disc. The pressure difference of said hydraulic system is a function of engine speed.  
     
     
         11 . The system as claimed in  claim 2  wherein the amount of said separation between two arms in the said variable rocker arm assembly changes when the said rocker arm pivot alters its position.  
     
     
         12 . The system as claimed in  claim 3  wherein the amount of said separation between two arms in the said variable lift rocker arm assembly changes when the said rocker arm pivot alters its position.