Patent attributes
An emissions control method may include operating a hybrid vehicle in a first mode during which a combustion engine is off and an electric motor powers propulsion of the vehicle. An electrically heated catalyst (EHC) may be energized during the first mode. The method may further include determining an operating temperature of an additional catalyst in communication with exhaust gas from the combustion engine and operating the vehicle in a second mode after the first mode during which the engine powers propulsion of the vehicle. The engine may operate in a catalyst combustion mode during the second mode when the operating temperature is below a first predetermined limit. The catalyst combustion mode may include operating the engine at an air-fuel ratio of less than stoichiometry and injecting air into exhaust gas from the engine at a location before the additional catalyst to create an exothermic reaction within the additional catalyst.
