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A novel process for coating and assembling metal converters utilizing precoated foil as building blocks has been developed which yields a converter capable of withstanding typical industry specified hot vibration protocols. The precoating process used here results in uniform catalyst coating distributions with coating adhesion to the foil on a par with the coatings' adhesion to ceramic substrates. FTP and MVEG vehicle emission performance of this unique precoated metal converter design versus a more conventional dip-coated metal monolith (parts with the same volume, cell density, and tri-metal catalyst coating), exhibited improved catalyst emission breakthrough efficiencies with respect to HC, CO, and NOx after two different engine-aging protocols. These advantages were observed on three different test vehicles across most phases of these driving cycles.

The development of electrically heated converter (EHC) systems that combine heated and unheated core functions is discussed. This “cascade” converter approach provides for effective energy transfer between the electrically heated core and a small volume, unheated metallic core. Cascade-type EHC systems demonstrate improved cold start hydrocarbon emission performance in FTP vehicle tests, versus early EHC configurations which combined a small volume EHC with a large volume, main converter. Examples of the FTP emission performance of cascade-type EHC systems are presented for both low-mileage situations and after accelerated engine aging that simulates high-mileage applications. The design flexibility of current cascade-type EHC configurations is reviewed with emphasis on reduced electrical energy consumption and mechanical durability. Recent designs have been developed which combine both the heated and unheated cascade functions into a single metal core.

Electrically heated catalysts (EHCs) have been developed over the last few years for controlling cold-start automobile exhaust emissions. Many technical obstacles will have to be overcome to commercialize EHCs. In particular, automobile designers will face system-related issues, due to the high power demands of the EHC. This paper is the result of an effort to acquire data that will help resolve those system-related issues. A fleet of 20 cars in normal driving service was equipped with operating EHC systems. This paper presents preliminary findings obtained after approximately six months of operation of the fleet. Preliminary battery and component durability are presented, as well as representative emission results. A second paper (Part II) is envisioned to present findings after approximately two years of operation.

Emission performance of an electrically heated catalytic converter is presented for both low-mileage tests and after exhaust aging using a 300 h dynamometer schedule. The aged converter system maintained its ability to significantly reduce cold start hydrocarbon and CO emissions on a late model gasoline-fueled passenger car. In these tests HC and CO emissions were reduced by 76% and 92%, respectively, during the first 140 seconds of the FTP urban driving cycle by operating the aged converter with resistance heating and air injection, in comparison to operation of the same aged converter in an unheated configuration. These reductions for heated operation versus unheated operation were comparable to the 80% HC and 96% CO cold start emission reductions observed in low-mileage testing of the same converter.

Resistively heated metal substrate converters have been developed to improve the cold start emission characteristics of light duty vehicles. Electrically heated metal monoliths have been designed and tested that are able to reach catalytic light-off temperatures (350°C) in less than 30 sec. using a conventional 12 volt electrical system. A solid state controller has been developed that mates with a vehicle's 12 volt system, delivers high currents to the metal monolith, and controls the converter temperature to a given setpoint. Gasoline vehicle emission data are presented that show substantial improvements in cold start HC and CO emissions under both normal ambient and reduced ambient conditions by combining resistance heating and secondary air injection. In these tests Bag 1 HC and CO emissions were reduced by more than 50% versus the same metal monolith converter tested in an unheated configuration.