| 摘要 |
<p>An exhaust emission control device having an NOx catalyst and an alternative path bypassing the NOx catalyst for increasing the reliability of exhaust emission control, comprising an SOx adsorbent (17) installed in an exhaust emission path of an internal combustion engine, a main NOx catalyst (20) installed in the exhaust emission path on the downstream side of the SOx adsorbent, an alternative tube (26) which branches from the exhaust emission path at a position between the SOx adsorbent (17) and main NOx catalyst (20) and bypasses the main NOx catalyst (20), and an exhaust emission switching valve (28) which is installed at the start end part of the alternative tube (26) and switches the flow of exhaust emission between the main NOx catalyst (20) and alternative tube (26), wherein a sub NOx catalyst (24) is installed in the alternative tube (26) so that, when the exhaust emission switching valve (28) is controlled so that exhaust emission is led to the main NOx catalyst (20) and does not flow into the alternative tube (26),leaked exhaust emission is controlled by the sub NOx catalyst (24) even if exhaust emission is leaked from the exhaust emission switching valve (28) into the alternative tube (26).</p> |
