Electrically heatable catalytic converter

DETAILED DESCRIPTION An object of the present invention is to provide an electrically heatable catalytic converter having a sufficient durability, particularly to thermal stress.
Another object of the present invention is to provide an electrically heatable catalytic converter capable of operating with reduced electric power requirements.
According to one aspect of the present invention, there is provided an electrically heatable catalytic converter for converting pollutant materials from an engine, such as carbon monoxide, unburned hydrocarbons, nitrogen oxides etc.
, to carbon dioxide, nitrogen and water, said converter comprising: a catalytic core comprising at least one metal strip and at least one insulation layer spirally wound together to form a spiral electrical path, said catalytic core having a peripheral region thereof, in which only said metal strip is wound without an intervening insulation layer and contacts as metal to metal; a metal case for accommodating said catalytic core in such a manner that said peripheral region of the catalytic core directly contacts said metal case; and means for supplying electric power to said catalytic core.
According to this embodiment of the present invention, the insulation layer does not exist in the peripheral region of the catalytic core and therefore the electrical resistance in this region is very small.
Therefore, thermal durability can be improved in the peripheral region which is subjected repeatedly to a relatively large thermal stress.
In addition, the outer periphery of the catalytic core can be firmly secured to the metal case.
According to another aspect of the present invention, there is provided an electrically heatable catalytic converter for converting pollutant materials from an engine, such as carbon monoxide, unburned hydrocarbons, nitrogen oxides etc.
, to carbon dioxide, nitrogen and water, said converter comprising: a catalytic core comprising a rod-like center electrode, at least one metal strip and at least one insulation layer spirally wound together about said center electrode to form a spiral electrical path, said catalytic core having a central region thereof adjacent to said center electrode, in said central region only said strip is wound without an intervening insulation layer and contacts as metal to metal; a metal case for accommodating said catalytic core; and means for supplying an electric power to said catalytic core