1994-03-01

A Structurally Durable EHC for the Exhaust Manifold 940466

It is well known that an EHC (Electrically Heated Catalyst) is very effective in reducing cold start HC emissions. However, the large electric power consumption of the EHC is a major technical issue. When installed in the exhaust manifold, the EHC can take advantage of exhaust heat to warm up faster, resulting in a reduced electric power demand. Therefore, a structurally durable EHC which can withstand the severe manifold conditions is desirable.
Through the use of a extruded monolithic metal substrate, with a flexible hexagonal cell structure and a special canning method, we have succeeded in developing a structurally durable EHC.
This new EHC installed in the exhaust manifold with a light-off catalyst directly behind it demonstrated a drastic reduction in FTP (Federal Test Procedure) Total HC emissions. Even after severe engine aging equivalent to 50,000 miles (850 °C x 100 Hours with a fuel cut mode), emissions continued to be reduced by more than 50 %, with less than 2kw of post heat, when tested in a 2 liter engine car.
This low wattage and durable EHC can be a practical solution to meet LEV/ULEV regulations.

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