| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust gas purification system which can suppress a deterioration in fuel economy and the occurrence of NHslip and includes a DOC (Diesel Oxidation Catalyst), a DPF (Diesel Particulate Filter) and SCR (Selective Catalytic Reduction).SOLUTION: Two lines of bypass pipes 6A, 6B in which NOx adsorbents 9A, 9B having heating heaters 8A, 8B are interposed respectively, are attached to a pipe line 1 of the upstream side of a DOC 2 in parallel. When a temperature of the DOC 2 is less than a temperature α, exhaust gas G is caused to flow through only one side 6A of the bypass pipes and, when the temperature of the DOC 2 is α or more and a temperature of a DPF 3 is in the proper temperature range, the exhaust gas G is caused to flow through only the pipe line 1. Further when an increasing rate of revolution speed of a diesel engine or an acceleration of a vehicle exceeds a set value &bgr;, the exhaust gas G is caused to flow through only either of the bypass pipes 6A, 6B and, at the same time, oxidized gas is supplied to the other bypass pipe 6A/6B to generate NOand, when being less than &bgr;, the exhaust gas G is caused to flow through the pipe line 1 and the bypass pipes 6A/6B to heat NOx adsorbent. |
