| 摘要 |
An exhaust system or an engine (12) includes a lean NOx catalytic device (18), and a heat exchanger (70) positioned upstream of the catalytic device (18). Control means (44, 46) controls a valve (36) to regulate exhaust gas flow through the heat exchanger (70) or along a bypass path (26). The heat exchanger (70) can cool the exhaust gases to ensure that the maximum operating temperature of the catalytic device (1) is not exceeded. During use, the heat exchanger (70) can be bypassed to allow high temperature purge cycles. |
