Variable cam system

Abstract

A variable cam system which in one embodiment includes cams having a contacting surface formed by an involute curve, a cam shaft, and an actuator for moving the shaft in a longitudinal direction. The operating displacement of the cams may be varied by longitudinally moving the cam shaft.

1 . A variable cam system variably opening/closing intake and exhaust valves comprising: 
 a cam shaft coupled to a timing gear movable in a longitudinal direction thereof;    an actuator moving the cam shaft in the longitudinal direction of the cam shaft; and    a plurality of cams secured to the cam shaft to open/close the valves by rotating, a contacting surface of each cam formed as a curved surface along the longitudinal direction of the cam shaft such that an operating displacement of the cam is varied corresponding to a longitudinal direction movement of the cam shaft.    
   
   
       2 . The system of  claim 1 , wherein the contacting surface of each cam is formed as an involute curve.  
   
   
       3 . The system of  claim 1 , further comprising uppermost points on the contacting surface of each cam formed at both ends of the cam such that an operating displacement of the cam increases as it goes from a center portion to either end along the longitudinal direction of the cam shaft; and 
 the uppermost points deviate from each other by a predetermined angle with respect to a rotating direction of the cam shaft.    
   
   
       4 . The system of  claim 1 , wherein a bearing is disposed at an end of a tappet of each valve contacting the contacting surface of each cam.  
   
   
       5 . The system of  claim 4 , wherein the bearing is a ball bearing.  
   
   
       6 . A variable cam system for opening and closing intake and exhaust valves comprising: 
 a cam shaft defining a longitudinal direction;    an actuator coupled to the shaft and operable to move the shaft back and forth in the longitudinal direction;    a plurality of V-shaped cams attached to the shaft in a spaced-apart relationship to each other, each cam having a center portion and an end on either side of the center portion; the ends being higher than the center portion;    at least one valve operably coupled to each cam and displaceable by rotational movement of the cam;    wherein a relative longitudinal position of each cam is adjustable in relation to each at least one respective valve by the actuator.    
   
   
       7 . The system of  claim 6 , wherein each valve is connected to a tappet having a bearing at one end that contacts one of the cams, each tappet displaceable up and down by rotational movement of each cam.  
   
   
       8 . The system of  claim 6 , wherein each cam is shaped as an involute curve.  
   
   
       9 . The system of  claim 7 , wherein a maximum displacement of each tappet occurs when an end of the cam contacts the bearing.  
   
   
       10 . They system of  claim 6 , further comprising the actuator including a rack and a pin.