| 摘要 |
A engine exhaust system is disclosed for reducing the amount of hydrocarbons emitted during engine start-up (cold-start), before the catalytic converter has attained its effective operating temperature. The system includes a flow diverter, in particular a secondary air jet adapted to direct substantially all of the engine exhaust through a molecular sieve structure during cold-start, and to direct the engine exhaust stream directly from the light-off catalyst to the burnoff catalyst, bypassing the molecular sieve structure after light-off.
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