Core for an electrically heatable catalytic converter

DETAILED DESCRIPTION OF THE INVENTION As indicated above, the present invention is a novel arrangement and structure for a core useful in an electrically heatable catalytic converter.
In order to produce the most effective and least expensive electrically heatable catalytic converter or EHC, requires a careful balance between the electrical requirements and the physical requirements of the device.
This has been achieved in the devices of the present invention in that they will survive the Hot Tests and at the same time have relatively low power requirements and will come up to temperature quickly.
For use in automotive applications, EHC designs need to be suitable for low cost mass production and be mechanically and catalytically durable.
A critical requirement is the ability to reach a catalyst temperature of 650.
degree.
F.
or more within several seconds after voltage is applied to the terminals.
Further, for the EHC to have widespread use, certain designs must be adaptable to higher voltage systems, e.
g.
, 24 and 48 volt systems, which are expected to become common in the next 10 years.
Electric vehicles are currently envisioned having a small constant speed gasoline driven engine to maintain battery charge and carrying batteries aggregating as much as 360 volts.
The generator engine would require an EHC.
Conformance to the design parameters set forth herein enable EHC's to fit within a small window dictated by the multiple requirements of mechanical durability, electrical rating flexibility, electrical integrity, metallurgical strength, including especially creep strength at operating temperatures up to 1850.
degree.
F.
or higher, catalyst durability, all in designs capable of mass production.
In particular, these parameters include mechanical durability in the Hot Tests.
These include the Hot Shake Test at 100 Hertz at about 900.
degree.
C.
, 50 G's for 100 hours; mechanical durability for 300 hours in the Hot Cycle Test at about 900.
degree.
C.
, a suitable level of catalyst activity at the conclusion of 100,000 mile durability tests so as to meet the California Ultra-Low Emission Vehicle (ULEV) or Low Emission Vehicle (LEV) standards, reasonable current draw so as to keep the battery size to a minimum, thermal mass sufficient to maintain "light-off" (oxidation of pollutants) when cold exhaust gases flow during a cold start mode; metal foil substrate with acceptable creep strength at 900