| 摘要 |
PURPOSE:To achieve EGR control high accuracy for long term by providing O2 sensor for detecting the concentration of O2 in intake-air mixed with exhaust gas and feedback controlling the opening of EGR valve such that O2 concentration will be at the predetermined level. CONSTITUTION:Under operation of engine, an electronic controller 12 will determine the engine operating state on the basis of engine rotation to be obtained through a rotation detector 11 and intake tube pressure to be detected through a pressure detector 4 and control an EGR valve 8 in accordance with the exhaust gas recirculation rate calculated with correspondence to the operating state. O2 sensor 5 will detect O2 concentration in intake-air mixed with exhaust gas to feedback control the opening of EGR valve 8 on the basis of detected signal such that O2 concentration will be at the predetermined level. Consequently, highly accurate exhaust gas recirculation can be achieved even when EGR valve 8 has deteriorated thus to maintain exhaust gas purification performance at high level. |
