Honeycomb Structure with Band-like Electrodes for Uniform Heating
Solution Overview
Problem
Existing honeycomb structures used as catalyst carriers and heaters in vehicle exhaust systems face issues with uneven temperature distribution and inadequate heat shock resistance, particularly when high voltage is applied, leading to potential damage to the power source circuit and insufficient exhaust gas purification at low engine start temperatures.
Innovation Solution
A honeycomb structure with a tubular design and band-like electrode members, featuring specific slit configurations and filling materials, is developed to regulate electrical resistivity and enhance heat generation while preventing excessive current flow and uneven temperature distribution, thereby improving heat shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heater made of metal is mounted on the honeycomb structure to raise exhaust gas temperature, then the catalyst temperature can be increased, but the metal heater has low electric resistance causing excessive current flow that damages the power source circuit
Solution Approach 1:
The invention changes the electrical resistivity parameter of the heater from metal (low resistance) to ceramic material (high resistance of 1-200 Ωcm). This parameter change allows the heater to generate sufficient heat while limiting current flow to safe levels, preventing power source circuit damage while maintaining the ability to raise catalyst temperature.
Solution Approach 2:
The invention uses a composite structure where a ceramic heating element is integrated with the honeycomb catalyst carrier. The ceramic material provides both heating function and electrical resistance, creating a composite system that simultaneously achieves temperature elevation and circuit protection without requiring separate metal heater and resistance adjustment mechanisms.
2Reliability
If a slit is formed in the metal heater to adjust resistance, then excessive current flow can be prevented, but the heater structure becomes more complex and heat generation efficiency decreases
Solution Approach 1:
The invention extracts the resistance adjustment function from the heater structure itself. Instead of forming slits in the heater to create resistance, the ceramic material inherently provides the required resistance (1-200 Ωcm), eliminating the need for structural modifications like slits and maintaining heater integrity while controlling current flow.
3Power
If high voltage is applied to the heater to generate sufficient heat, then the catalyst can reach operating temperature, but uneven temperature distribution occurs within the honeycomb structure
Solution Approach 1:
The invention segments the heating function by applying multiple electrode members (at least two) at different positions on the honeycomb structure. This segmentation distributes the heat generation sources throughout the structure, enabling more uniform heat distribution and preventing localized overheating while maintaining overall heating efficiency.
4Reliability
If the honeycomb structure is made of ceramic material with predetermined electrical resistivity, then heat can be generated without damaging the power source circuit, but heat shock resisting properties are insufficient
Solution Approach 1:
The invention optimizes the electrical resistivity parameter of the ceramic material to a specific range (1-200 Ωcm) that balances two requirements: high enough to limit current flow and protect the power source circuit, but not so high that it prevents sufficient heat generation. This parameter optimization simultaneously improves circuit protection and maintains heat shock resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The honeycomb structure effectively inhibits uneven temperature distribution and enhances heat shock resistance, ensuring safe and efficient heat generation even at high voltages, thus improving exhaust gas purification performance.
Implementation Method 1
a honeycomb structure which is a catalyst carrier and also functions as a heater when a voltage is applied thereto
Data Source
Figure 1~2
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Figure 4
AI summary
There is disclosed a honeycomb structure which is a catalyst carrier and also functions as a heater when a voltage is applied thereto and which can inhibit an unevenness of a temperature distribution when the voltage is applied thereto and has excellent heat shock resisting properties. A honeycomb structure 100 includes a honeycomb structure body 4 and a pair of electrode members 21, an electrical resistivity of the honeycomb structure body 4 is from 1 to 200 Ωcm, each of the pair of electrode members 21 is formed into a band-like shape extending in a cell extending direction of the honeycomb structure body 4, one electrode member 21 is disposed on a side opposite to the other electrode member 21 via a center of the honeycomb structure body 4, there are formed one or more electrode member slits 6a as slits 6 opened in an electrode member region P, there are formed one or more honeycomb structure body slits 6b as slits 6 opened in a honeycomb structure body region Q, and a depth of at least one of the electrode member slits 6a is deeper than a depth of at least one of the honeycomb structure body slits 6b.