| 摘要 |
<p>In a system wherein an oxygen sensor (28) is installed downstream from a NOx storage reduction catalyst (19), the output characteristic of the oxygen sensor (28) can be changed by running a constant current between the sensor electrodes by means of a constant current circuit provided on the outside of the oxygen sensor (28). Furthermore, during lean combustion control for the engine (11) the detection responsiveness of the oxygen sensor (28) with respect to the lean component is increased; thus, when NOx (the lean component) is discharged downstream from the catalyst (19) it can be detected quickly by the oxygen sensor (28). Meanwhile, during rich combustion control the detection responsiveness of the oxygen sensor (28) with respect to the rich component is increased; thus, when HC and CO (rich components) are discharged downstream from the catalyst (19), these can be detected quickly by the oxygen sensor (28).</p> |
