Patent ID: 7299775

Claim:
A variable valve operating device for mechanically changing the operating characteristic of a valve relative to rotation of a camshaft, comprising: a drive cam disposed on the camshaft; a control shaft disposed to extend in parallel with the camshaft, the control shaft being capable of changing the rotation position continuously or stepwise; a swing member swinging about an axis extending in parallel with the camshaft; a swing cam surface formed on the swing member, the swing cam surface making in contact with a valve support member for supporting the valve to press the valve in a lifting direction; a slide surface formed on the swing member so as to oppose the drive cam; an intermediate member disposed between the drive cam and the swing member, the intermediate member making in contact with both a cam surface of the drive cam and the slide surface; and an interlock mechanism for changing a position of the intermediate member on the slide surface by interlocking with the rotation of the control shaft; wherein the slide surface is formed to be curved toward the drive cam so that the distance from the center of the camshaft increases from the nearest point from the swing center of the swing member toward the farthest point from the swing center of the swing member within the area which the intermediate member contacts; and wherein the swing cam surface includes a nonoperating surface having a constant distance from the swing center of the swing member and giving the valve no lift and an operating surface disposed to continue into the nonoperating surface so that the distance from the swing center of the swing member becomes gradually greater, and a contact position of the valve support member on the swing cam surface shifts from the nonoperating surface to a side of the operating surface as the swing member swings.