In recent years, electrically heated catalysts (EHCs) have been developed to
achieve lower emissions. In several EHC heating methods, the direct heating
method, which an electric current is applied directly to the catalyst substrate,
can easily activate the catalyst before engine start-up. The research results
reported on the use of the direct heating EHC to achieve significant exhaust gas
purification during cold start-up .
From the perspective of catalyst loading, ceramics is considered to be a better
material for the substrate than metal due to the difference in coefficient of
thermal expansion between the catalyst and the substrate, but the EHC made of
ceramics has difficulties such as controllability of the current distribution,
durability and reliability of the connection between the substrate and the
electrodes. This paper reports about the hardware configuration of the direct
heating EHC made of ceramics, including the catalytic substrate as an electric
circuit, its electrode, and the insulation structure between pipe and them,
which can solve these difficulties.