| 摘要 |
PURPOSE:To control the open timing of an exhaust valve in accordance with the operating condition of an engine, in an exhaust valve being opened by oil pressure from a hydraulic piston which is driven through a cam interlocked with the rotation of the engine. by providing a pressure regulator in the way of the oil path. CONSTITUTION:An exhaust cam 1 interlocked with the rotation of an engine drives a piston 3 to lead a pressure oil from a hydraulic pump through a hydraulic operating conduit 4 into a hydraulic cylinder 6 thus opening an exhaust valve 12 through a piston 6a, a pushup rod 10a and a piston 10. The closing operation of the exhaust valve 12 is performed by feeding the pressure air to an air cylinder 8. A piston 17 being pushed by means of a spring 18 is arranged in the hydraulic operating conduit 4, and the pressure oil is fed to the rear face of a spring stopper 19 on the backface of the spring 18 with the feeding quantity of the pressure medium 21 being controlled through switching of a solenoid valve 20. When the pressure of oil is controlled in accordance with the operating condition of engine through switching of the solenoid valve 20, the pressure rise of oil in the hydraulic operating conduit 4 can be controlled thereby the valve-open timing of the exhaust valve is controlled.
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