| 摘要 |
<p>A method of treating exhaust gases from a gasoline engine after cold-start using an exhaust gas aftertreatment system comprises adsorbing unburnt hydrocarbons (HC) from the engine exhaust gas with an HC trap, supplying heated ambient air to the exhaust gas stream downstream of the HC trap when the temperature of the HC trap is sufficient that trapped HC are desorbed therefrom and passing the air-enriched gas stream over a three-way catalyst (TWC). An exhaust gas aftertreatment system for a gasoline-fuelled engine (1) for performing the method according to the invention comprises a HC trap (5), a downstream secondary air injection point (8), means for supplying heated ambient air to the secondary air injection point (9), a TWC (7) downstream of the point of secondary air injection, and means in use for operating the heated air supply means when the temperature of the HC trap is sufficient that HC trapped thereon are desorbed therefrom.</p> |
