| 摘要 |
<p>PURPOSE:To secure ignition temperature of a catalyzer in a honeycomb heater on the upstream part and to improve exhaust gas purifying performance by covering a plural number of honeycomb heaters with the specified catalyzer and by relatively lowering the ignition temperature of the catalyzer in the honeycomb heater on the upstream part. CONSTITUTION:In this multistage honeycomb heater, a plural number of honeycomb heaters consisting of conductive honeycomb structural bodies along the flow passage direction of exhaust gas. In this case, each of the honeycomb heaters is covered with a catalyzer consisting of a heat resistance unorganic oxide containing a precious metal as an active component. At least, the ignition temperature of the catalyzer in the honeycomb heater on the extreme upstream part is set lower than ignition temperature of the catalyzer in the honeycomb heater on the downstream part. In the meantime, slits 12 parallel in the through hole axial direction are arranged on the honeycomb heaters as resistance regulating systems. Consequently, even if the upstream side is cooled by the exhaust gas at the time when an engine works, it is possible to keep the catalyzer in the honeycomb heater on the upstream side at favourable ignition temperature.</p> |
