| 摘要 |
PURPOSE:To control a highly accurate exhaust gas recirculation rate as well as to control a stable idling speed, by installing a suction throttle valve, which opens or closes a suction passage, and an oxygen sensor which detects oxygen content in suction air mixed with exhaust gas. CONSTITUTION:A first suction throttle valve 4, which opens or closes a first suction passage 3 and simultaneously fully closes it in time of idle running in an engine 1, is installed. An exhaust gas recirculation control valve 18 makes exhaust gas recirculate from an exhaust pipe 17 to the suction passage 3. An oxygen sensor 11 detects oxygen content in suction air in which the exhaust gas is mixed. In order to control an idling speed, a second suction throttle valve 7 alone is opened or closed, while an exhaust gas quantity to be recirculated is controlled for feedback. Thus, a highly accurate exhaust gas recirculation rate and a stable idling speed both are controllable simultaneously. |
