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

Abstract

Continually 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 mechanical lash compensator. The pivot of the rocker arm alters when a variable valve lift disc rotates. The lash compensator comprises a cylindrical plunger inserted in a body. The plunger and the body are separated by a spring. The separation gap or lash varies depending on the amount of rocker arm pivot movement. The larger amount of lash results in lower valve lift and small amount of lash results in higher valve lift. 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 pivot 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 lash between the plunger and the body. 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 lash in the lash compensator increases, consequently the valve lift decreases. The valve timing, lift, and duration vary continuously depending on engine speed.

I claim:  
     
         1 . A continually variable valve timing, lift and duration system for an internal combustion engine comprises a lash compensator, a rocker arm, a variable lift disc, and a driving device.  
     
     
         2 . The system as claimed in  claim 1  wherein the said lash compensator comprises a cylindrical plunger, a body and a spring. The said plunger is inserted into the said body. The said plunger and the said body are separated by the said spring. The separation gap or lash varies depending on the rocker arm pivot position. Larger lash at cam base circle results in low valve lift, and smaller lash results in greater valve lift.  
     
     
         3 . The system as claimed in  claim 1  wherein the said rocker arm is end pivoted and the pivot is movable.  
     
     
         4 . The system as claimed in  claim 1  wherein the said rocker arm is center pivoted and the pivot is movable.  
     
     
         5 . 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.  
     
     
         6 . 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.  
     
     
         7 . The system as claimed in  claim 1  wherein the said variable lift disc can be a section of a circular disc.  
     
     
         8 . The system as claimed in  claim 1  wherein the said variable lift disc can be a lever.  
     
     
         9 . 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 moved by the said hydraulic system. The said spring pushes the said helical gear back towards its original position when the pressure of the said hydraulic system drops. And the pressure of said hydraulic system is a function of engine speed.  
     
     
         10 . 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.  
     
     
         11 . The system as claimed in  claim 7  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.