Variable Valve Apparatus

Abstract

A motor 30 or the like is used to drive a camshaft 22 or the like having a cam 18 or the like to push a valve 12 biased in the closing direction of the valve by a valve spring 17. Between the cam 18 or the like and the valve 12 is present a valve lifter 16 that abuts the cam 18 or the like. The valve lifter 16 includes a top face 16 a formed so that when viewed from the axial direction of the camshaft 22 or the like, a tangential direction to the nose tip 18 c of the cam 18 or the like inclines with respect to the direction perpendicular to the axial line of a valve stem 14.

1 .- 8 . (canceled) 
   
   
       9 . A variable valve apparatus that uses a motor to drive a camshaft including a cam for pushing a valve biased in the closing direction thereof by a valve spring, the variable valve apparatus, further comprising:
 a valve lifter which abuts the cam between the cam and the valve;   wherein the valve lifter includes a top face formed such that when viewed from an axial direction of the camshaft, the direction of a tangential line to a nose tip of the cam inclines with respect to the direction perpendicular to the axial line of a valve stem; and   wherein the inclining direction of the tangential line is a direction in which the distance between the tangential line and a bottom face of the valve lifter decreases as the inclination goes in the traveling direction of a contact point between the cam during forward rotation thereof and the valve lifter.   
   
   
       10 . A variable valve apparatus that uses a motor to drive a camshaft including a cam for pushing a valve biased in the closing direction thereof by a valve spring, the variable valve apparatus, further comprising:
 a valve lifter which abuts the cam between the cam and the valve;   wherein the valve lifter includes a top face formed such that when viewed from an axial direction of the camshaft, the direction of a tangential line to a nose tip of the cam inclines with respect to the direction perpendicular to the axial line of a valve stem; and   wherein the top face, when viewed from the axial direction of the camshaft, is formed into a convexedly curved shape to be convex toward the cam.   
   
   
       11 . The variable valve apparatus according to  claim 10 ,
 wherein on the top face formed into the convexedly curved shape to be convex toward the cam, an apical point whose height above the bottom face of the valve lifter is maximized, and the contact point between the nose tip and the valve lifter are spaced from each other when viewed from the axial direction of the camshaft.   
   
   
       12 . The variable valve apparatus according to  claim 10 ,
 wherein the top face having the convexedly curved shape to be convex toward the cam is formed to have a maximum achievable height above the bottom face of the valve lifter, on a central axis of the valve lifter; and   the camshaft is disposed such that a central axis thereof and the central axis of the valve lifter do not intersect with each other when viewed from the axial direction of the camshaft.   
   
   
       13 . The variable valve apparatus according to  claim 10 ,
 wherein the camshaft is disposed such that a central axis thereof intersects with the central axis of the valve lifter when viewed from the axial direction of the camshaft; and   the top face having the convexedly curved shape to be convex toward the cam is formed such that when viewed from the axial direction of the camshaft, an apical point whose height above the bottom face of the valve lifter is maximized takes up an offset position relative to the axial line of the valve stem.   
   
   
       14 . The variable valve apparatus according to  claim 9 ,
 wherein the top face, when viewed from the axial direction of the camshaft, is an inclined surface having a constant gradient.   
   
   
       15 . The variable valve apparatus according to  claim 9 , further comprising:
 electric power supply control means for stopping supply of electric power to the motor when a command value assigned to the motor to drive the camshaft reaches a predetermined value.   
   
   
       16 . The variable valve apparatus according to  claim 9 , further comprising:
 a torque reduction mechanism that generates a reduced torque for reduction in a driving torque of the camshaft;   wherein the torque reduction mechanism is constructed such that the reduced torque is small in comparison with a camshaft torque based upon a biasing force of the valve spring.   
   
   
       17 . The variable valve apparatus according to  claim 10 , further comprising:
 electric power supply control means for stopping supply of electric power to the motor when a command value assigned to the motor to drive the camshaft reaches a predetermined value.   
   
   
       18 . The variable valve apparatus according to  claim 10 , further comprising:
 a torque reduction mechanism that generates a reduced torque for reduction in a driving torque of the camshaft;   wherein the torque reduction mechanism is constructed such that the reduced torque is small in comparison with a camshaft torque based upon a biasing force of the valve spring.