| abstract |
A honeycomb heater comprising a honeycomb structure (1) which is made of a conductive material and which has a number of passages substantially parallel to a gas flow direction partitioned by partition walls and which has end surfaces on a gas inlet side and a gas outlet side as well as an outer periphery, and at least two electrodes (5) for electrification provided on the honeycomb structure, said honeycomb heater being characterized in that a plurality of slits (10,11) extend in a direction of the passages between the electrodes of the honeycomb structure so that a current flow path may be prolonged, whereby resistance is adjusted, and one or more of a slit forming position, a slit length and a space between each pair of slits are adjusted so that a specific region of the honeycomb heater may be locally heated more quickly as compared with the other region at the time of the electrification. According to the present invention, harmful substances in an exhaust gas discharged from an internal combustion engine, particularly HC generated in large quantities at the time of a cold start can be effectively purified with a low electric power. |