| 摘要 |
<p>A heater unit has a honeycomb heater comprising (a) a metallic honeycomb structure having a large number of passages parallel to the direction of an exhaust gas flowing through the heater unit and (b) at least one electrode for electrification of the honeycomb structure, attached to the honeycomb structure, and a metallic casing for holding the honeycomb heater therein via at least one metallic supporting member. The heater unit also has an insulation portion provided at least either at the connection area where the honeycomb heater and the supporting member are connected or at the connection area where the supporting member and the casing are connected. The supporting member has such a structure so as to be able to absorb the displacement of the honeycomb heater which appears in a direction substantially perpendicular to said gas flow direction, and has a function of fixing the honeycomb heater against its displacement which appears in the gas flow direction. A gas flow-controlling means is provided at the inlet and/or side of the honeycomb heater so that the amount of the exhaust gas flowing outside the honeycomb heater is controlled at 20% or less of the total flow amount of exhaust gas. The heater unit, when exposed to severe driving conditions of automobiles, etc. and subjected to vibration and the expansion and contraction caused by thermal shock, gives rise to neither breakage of honeycomb heater nor peeling and can maintain the purification ability for exhaust gases of automobiles, etc.</p> |
