Electrically-Heated Catalyst System Conversions on Two Current-Technology Vehicles

Two different configurations of electrically-heated catalyst systems were installed on two new production vehicles. A 1990 Buick LeSabre was evaluated with a heated catalyst placed directly in front of the main production catalytic converter while a 1990 Toyota Celica was evaluated with an electrically-heated catalyst placed between the main close-coupled catalytic converter and a smaller downstream production catalytic converter. Initial laboratory studies involved examination of heating strategies to minimize electrical energy requirements, a variety of off-board battery and recharging configurations for their effect on emissions, and multiple air injection strategies to achieve minimum hydrocarbon emissions while avoiding a NO_x penalty. Final efforts involved installation of optimized, complete on-vehicle electrically-heated catalyst systems for subsequent on-road mileage accumulation. The vehicle conversions, albeit unaged, exhibited FTP emissions which show promise of meeting the California Ultra-Low Emission Vehicle standards, and have contributed to adoption of low emission standards by the California Air Resources Board.