| 摘要 |
PURPOSE:To prevent the blow-back and temperature fall of gas remaining in a cylinder and effectively decrease NOx without deteriorating the running performance of an engine, by causing the closing period of an exhaust valve and the opening period of an intake valve to correspond to each other and controlling the relation between both the periods to vary depending on the running condition of the engine. CONSTITUTION:A tridimensional cam 10 for an exhaust valve is mounted on a cam shaft 2 installed over a cylinder head 1. A piston 7 is coupled to the end of the cam shaft. Oil pressure, which rises in connection with the degree of opening of an accelerator pedal, acts on the piston 7 to displace the cam shaft 2 to advance the closing period of the exhaust valve 11. An intake valve is controlled by the same mechanism so that the opening period of the intake valve is delayed depending on the closing period of the exhaust valve 11. As a result, gas remaining in a cylinder is regulated depending on a running condition so that most of the gas is enclosed in the cylinder and the temperature of the gas in the cylinder is raised. Thus, combustion is improved and NOx is effectively decreased without deteriorating the running performance of an engine. |
