| 摘要 |
PURPOSE:To lower the specific fuel consumption of an engine, by reducing the work required for driving an exhaust valve by making the exhaust valve in an outwardly opened type, and introducing high-pressure work oil to the top surface of a hydraulic piston at one end of the exhaust valve at the time of closing the exhaust valve. CONSTITUTION:An exhaust valve 40 is made in a type that is opened outwards of a combustion chamber 10, and a cam 41 is made in recessed shape which decreases the lift of a roller 33 at the time of opening the exhaust valve 40. When a cam shaft 31 is turned and the roller 33 is lowered by a cam 41, pressure of work oil in a hydraulic cylinder 17 begins to drop. With increasing of the crank angle, the exhaust valve 40 begins to open, and work gas begins to flow out to an exhaust passage 19 from the combustion chamber 10. Finally, only the compressive force of a valve spring 16 is acted to the exhaust valve 40. With further increasing of the crank angle, the roller 33 is pushed upward again by the cam 41 and the pressure of work oil is raised to compress the valve spring 16, so that the exhaust vlave 40 begins to close. |
