Variable valve timing system for an internal combustion engine

Abstract

The invention describes a rocker arm displacement system for variable valve timing in internal combustion engines. More specifically, the system provides a rocker arm displacement system including a rocker arm having a pivot, a cam-contacting portion and a valve stem contacting portion and a linear displacement system for linear displacement of the cam-contacting portion with respect to a variable profile cam.

1 . A rocker arm displacement system for linear displacement of a rocker arm having a cam contacting portion with respect to a rotating, variable-profile cam comprising a linear displacement system operatively connected to a rocker arm.  
     
     
         2 . A rocker arm displacement system comprising: 
 a rocker arm having a pivot, a cam contacting portion and a valve stem contacting portion;    a linear displacement system for linear displacement of the cam contacting portion with respect to a variable profile cam    
     
     
         3 . A rocker arm displacement system as in  claim 2  wherein the cam-contacting device has improved thermal dissipation properties.  
     
     
         4 . A rocker arm displacement system as in  claim 2  wherein the cam contacting portion has a coefficient of thermal expansion less than 3×10 −6 /degree Celsius.  
     
     
         5 . A rocker arm displacement system as in  claim 2  wherein the cam contacting system is a ball bearing and a bearing race and support and wherein the coefficient of thermal expansion of the ball bearing is less than the coefficient of thermal expansion of the bearing race and support.  
     
     
         6 . A rocker arm displacement system as in  claim 2  wherein the cam contacting system is ceramic.  
     
     
         7 . A rocker arm displacement system as in  claim 2  wherein the cam contacting system is any one of silicon nitride or silicon carbide.  
     
     
         8 . A rocker arm displacement system as in  claim 2  wherein the cam contacting system is selected from any one of CERALLOY 147-31E, 147-3 IN, 147-1E, or 147-1.  
     
     
         9 . A rocker arm displacement system as in  claim 2  wherein the cam contacting system is selected from any one of a radiused wheel, a ball bearing or a semi-spherical surface and wherein the cam contacting surface is selected from any one of CERALLOY 147-31E, 147-31N, 147-1E, or 147-1.  
     
     
         10 . A rocker arm displacement system as in  claim 2  wherein the valve stem contacting portion is silicon nitride.  
     
     
         11 . A rocker arm displacement system as in  claim 2  wherein the linear displacement system includes a sliding block operatively connected to a linear displacement cylinder and the sliding block pivotally retains the rocker arm.  
     
     
         12 . A rocker arm displacement system as in  claim 12  wherein the sliding block includes a hydraulic lash adjustment system.  
     
     
         13 . A rocker arm displacement system as in  claim 13  wherein the hydraulic lash adjustment system includes a piston within the sliding block for setting the range of motion of the rocker arm within the sliding block.  
     
     
         14 . A rocker arm displacement system as in  claim 2  wherein the valve stem includes a tip bearing for engagement with the rocker arm.  
     
     
         15 . A rocker arm displacement system as in  claim 2  wherein the rocker arm has a lash adjustment system adjacent the valve stem end of the rocker arm.  
     
     
         16 . A rocker arm displacement system as in  claim 2  wherein the rocker arm has a tip bearing for engagement with the valve stem.  
     
     
         17 . A rocker arm displacement system as in  claim 2  wherein the cam contacting portion is a ball bearing for engagement with the cam.  
     
     
         18 . A rocker arm displacement system as in  claim 2  wherein the cam contacting portion is a tapered wheel for engagement with the cam.  
     
     
         19 . A rocker arm displacement system as in  claim 2  wherein the rocker arm is pivotally connected to the valve stem.  
     
     
         20 . A rocker arm displacement system as in  claim 2  wherein the rocker arm pivot is located centrally to the valve stem end and cam contacting end of the rocker arm.  
     
     
         21 . A rocker arm displacement system as in  claim 2  wherein the rocker arm pivot is located at a first end of the rocker arm.  
     
     
         22 . A rocker arm displacement system as in  claim 5  wherein the cam contacting system is any one of a radiused wheel, a ball bearing or a semi-spherical surface and is a silicon nitride selected from any one of CERALLOY 147-31E, 147-31N, 147-1E, or 147-1 or a silicon carbide.  
     
     
         23 . A rocker arm displacement system as in  claim 22  wherein the valve stem contacting portion is silicon nitride.  
     
     
         24 . A rocker arm displacement system as in  claim 23  wherein the linear displacement system includes a sliding block operatively connected to a linear displacement cylinder and the sliding block pivotally retains the rocker arm.  
     
     
         25 . A rocker arm displacement system as in  claim 24  wherein the sliding block includes a hydraulic lash adjustment system.  
     
     
         26 . A rocker arm displacement system as in  claim 25  wherein the hydraulic lash adjustment system includes a piston within the sliding block for setting the range of motion of the rocker arm within the sliding block.  
     
     
         27 . A rocker arm displacement system as in  claim 26  wherein the valve stem includes a tip bearing for engagement with the rocker arm.  
     
     
         28 . A rocker arm displacement system as in  claim 27  wherein the rocker arm has a lash adjustment system adjacent the valve stem end of the rocker arm.  
     
     
         29 . A rocker arm displacement system as in  claim 28  wherein the rocker arm has a tip bearing for engagement with the valve stem.  
     
     
         30 . A rocker arm displacement system comprising: 
 a rocker arm having a pivot, a cam contacting system and a valve stem contacting system, the cam contacting system a silicon nitride ball bearing rotatably retained within the rocker arm;    a silicon nitride valve stem tip for operative engagement with the valve stem contacting system; and    a sliding block operatively connected to a linear displacement cylinder for linear displacement of the cam contacting portion with respect to the variable profile cam wherein the sliding block pivotally retains the rocker arm and wherein the sliding block includes a hydraulic lash adjustment system.    
     
     
         31 . A method of retrofitting an internal combustion engine with a rocker arm displacement system as in  claim 1 , the internal combustion engine having a valve cover, valve stems, a rocker arm assembly and a camshaft comprising the steps of: 
 a) removing the valve cover to expose the valve stems, rocker arm assembly and camshaft;    b) removing the camshaft and installing a variable profile camshaft;    c) installing a rocker arm displacement system having a rocker arm, a cam contacting portion, a valve stem contacting portion and a linear displacement system.    
     
     
         32 . An internal combustion engine characterized by a rocker arm displacement system for linear displacement of a rocker arm with respect to a camshaft.