| 摘要 |
PURPOSE:To prevent white fume and misfiring from taking place to reduce NOx, by providing an exhaust recirculation control valve for controlling the flow rate of exhaust gas, an absolute pressure valve for generating a constant pressure and a fluid pressure regulating valve for generating fluid pressure in accordance with engine load. CONSTITUTION:An exhaust gas recirculation control valve 12 is connected to an exhaust passage 10 and an intake-air passage 6a. A negative pressure control valve 30 communicates an inlet port 31 with the outlet port of a pump 90, a negative pressure chamber 48 with the outlet port 82 of a negative pressure regulating valve 80, and a negative pressure chamber 52 with the outlet port 62 of an absolute pressure valve 60, respectively. In a low load operating range the output pressure to the negative pressure regulating valve 80 is limited by the absolute pressure valve 60 so that the valve opening degree of the exhaust gas recirculation control valve 12 is decreased. With this arrangement, the altitude compensation of the EGR rate may be made to prevent white fume and misfiring from taking place. |
