Cam position measurement for embedded control VCT systems using non-ideal pulse-wheels for cam position measurement

Abstract

In a VCT system having a phaser and pulse wheels on driving and driven shafts respectively in which the pulse wheels have known tooth distribution thereon, a device and method is used for adjusting values of a controller that controls the timing between the driving and driven shaft. Additional subroutines are performed with respect to the driving shaft tooth wheel and the driven shaft tooth wheel respectively. The known tooth distribution includes non-symmetric tooth distribution.

1 . In a VCT system having a phaser for adjusting an angular relationship between a crank angle of the crank shaft and a cam angle of a cam shaft, the system further has a controller adapted to determine the angular relationship based on equally spaced teeth distributed upon the circumference of at least one tooth wheel coupled to either the crank shaft or the cam shaft, a method comprising the steps of: 
 a) providing a tooth wheel having a physically non-symmetrical tooth distribution on the circumference of the wheel; and    b) adjusting the physically non-symmetrical tooth distribution into a symmetrical tooth distribution for further processing by the controller.    
   
   
       2 . In a VCT device having a phaser for adjusting an angular relationship between a crank angle of the crank shaft and a cam angle of a cam shaft, the system further has a controller adapted to determine the angular relationship based on equally spaced teeth distributed upon the circumference of the crank shaft and the cam shaft respectively, a method comprising the steps of: 
 providing a crank tooth wheel having known tooth distribution;    providing a cam tooth wheel having known tooth distribution; and    using the controller for adjusting values known to the controller as needed.    
   
   
       3 . The device of  claim 2 , wherein the using step comprises running a cam pulse interrupt subroutine for determining a first set of adjusted values.  
   
   
       4 . The device of  claim 2 , wherein the using step comprises running a crank pulse interrupt subroutine for determining a second set of adjusted values.  
   
   
       5 . The device of  claim 2 , wherein the crank tooth wheel having known tooth distribution comprises symmetric tooth distribution.  
   
   
       6 . The device of  claim 2 , wherein the crank tooth wheel having known tooth distribution comprises non-symmetric tooth distribution.  
   
   
       7 . The device of  claim 2 , wherein the cam tooth wheel having known tooth distribution comprises symmetric tooth distribution.  
   
   
       8 . The device of  claim 2 , wherein the cam tooth wheel having known tooth distribution comprises non-symmetric tooth distribution.