| 摘要 |
PURPOSE:To make it possible to simply and surely confirm the function of an EGR device without any new device being added, by detecting changes in the amount of EGR in the form of variations in the concentration of exhaust gas in order to discriminate where the function of the EGR device is good or not. CONSTITUTION:An engine 1 has an exhaust passage 14a, 14b for recirculating a part of exhaust gas into an intake manifold 2, in an exhaust manifold, and an EGR valve 5 is disposed in the intermediate section of the exhaust passage 14a, 14b. Further, a control computer 4 controls the EGR valve 5 and a fuel injection valve 6 in accordance with signals from a rotating angle sensor 12, an intake-air volume sensor 8, an oxygen sensor 3, an opening degree detector 15 and a detector 11 for detecting the operating condition of the engine including the temperature of the latter. Further, the EGR valve 5 is operated in, for example, a stepwise manner in a predetermined condition of the engine 1. Further, when the the amount of EGR is large, it is monitored that a signal from the oxygen sensor 10 turns into the lean side to discriminate whether the function of the EGR valve is good or not. |
