| 摘要 |
PURPOSE: A variable device of an intake/exhaust valve is provided to realize high output and low air-fuel ratio by variably controlling opening and shutoff timing and opening degree of a valve at the entire region of an engine with electrical control of hydraulic pressure of an actuator. CONSTITUTION: In an intake/exhaust valve device, an actuator operated by hydraulic pressure is placed between a cam(4) and a valve(6). The actuator includes a housing having upper and lower cylinders, upper and lower plungers(20,22) received in the cylinders and upper and lower elastic support units. With response to supply of hydraulic pressure to an inlet, the hydraulic pressure flows into the lower cylinder to lift down the lower plunger. Then, the entire length of the actuator extends and opening timing of the valve is advanced. If the hydraulic pressure is released, the lower plunger is lifted up by the elasticity of a valve spring supporting the valve. On a discharge path(34), a path opening and shutoff valve is installed to control hydraulic pressure supplied to the actuator corresponding to an electrical signal of a crank position wheel sensor. A control unit controls the path opening and shutoff valve to shut off the path in high speed operation. According to variation of lifting degree and valve opening and shutoff timing corresponding to a vehicle speed, high output and low air-fuel ratio are realized.
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