| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device for an internal combustion engine for improving the performance of purifying NOx with a catalyst device independently of the operated condition of the internal combustion engine while maintaining sufficient performance of purifying components to be purified excluding NOx with the catalyst device. <P>SOLUTION: A target value Vtgt for an output Vout of an O<SB>2</SB>sensor (an exhaust gas sensor) 8 arranged on the downstream side of the catalyst device 4 is set to be such a value that CO, HC, NOx purifying rates are all high on an equal basis in the operated condition (the low load operated condition) of the engine 1 where the concentration of NOx in exhaust gas is relatively low. The target value Vtgt is set to be such a value that the NOx purifying rate is higher in the operated condition (the high load operated condition) of the engine 1 where the concentration of NOx in exhaust gas is relatively high. The air-fuel ratio of the exhaust gas is controlled to converge the output Vout of the O<SB>2</SB>sensor to the target value Vtgt. <P>COPYRIGHT: (C)2004,JPO</p> |
