| 摘要 |
PURPOSE: A device for varying the strength of a valve spring of an engine is provided to reduce the unnecessary loss of engine driving torque in a low-speed operation range by varying the strength of a valve spring depending on the operating condition of an engine. CONSTITUTION: A valve spring(16) is fitted to the outer circumference of a valve stem(14a). The lower end of the valve spring is supported on a mounting member(10a)placed on a cylinder head(10), while the upper end is supported on a retainer assembly(18). An actuator(26) is installed in the lower portion of the mounting member. The operation of the actuator is controlled by a control unit(28). The control unit is connected with a speed sensor(30) sensing the rotational speed of a crankshaft. If an engine is operated at a low speed, the control unit descends the actuator. Then, the mounting member moves downward and the mounting length of the valve spring is extended.
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