| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve the NOx reduction ratio by an NOx catalyst, when purifying exhaust gas. <P>SOLUTION: This exhaust control system includes a bypass passage 108 for bypassing a downstream side NOx catalyst reactor 109 by arranging the NOx catalyst (an upstream side NOx catalyst in an upstream side NOx catalyst reactor 104 and a downstream side NOx catalyst in the downstream side NOx catalyst reactor 109) in series on the upstream side and the downstream side of an exhaust passage 101, and a flow passage switching valve 107 arranged on the downstream side of the upstream side NOx catalyst reactor 104 and on the upstream side of the downstream side NOx catalyst reactor 109 and switching whether the exhaust gas is made to flow to or bypass the downstream side NOx catalyst, in an exhaust emission control device 10, and controls switching of a flow passage by a flow passage switching valve 107 based on not only the temperature of the downstream side NOx catalyst but also a flow rate of the exhaust gas. This switching control is performed by a flow passage switching control part 2033 of a control part 203 of an ECU 20. The exhaust gas is bypassed when the downstream side NOx catalyst is the high temperature and the exhaust gas is a large flow rate. <P>COPYRIGHT: (C)2009,JPO&INPIT |
