| 摘要 |
PURPOSE: A variable valve timing device is provided for a taper shaped cam to control valve timing through moving a camshaft toward a shaft direction by using centrifugal force of a ply weight. CONSTITUTION: At an initial state of an engine, a timing pulley(5) receives rotational force of the engine through a crankshaft pulley(1). A taper cam(15) is operated by a camshaft(11) to open and close a valve(17). At a low speed of the engine, the rotational force is small to generate a small amount of centrifugal force to a ply weight(19). Thus, elastic force of an elastic spring(13) is over the centrifugal force to open and close the valve in a located state of a valve tappet on a narrow inclined surface of the taper cam. In case of a high speed of the engine, the rotational force is increased to generate a larger centrifugal force to the ply weight. Thus, the centrifugal force is over the elastic force of the spring for the ply weight to push the camshaft through a push lever(25). Then, valve timing is varied by operating opening and closing of the valve in a located state of the valve tappet on a wide inclined surface of the taper cam.
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