Gradient Resistivity Honeycomb Structure for Exhaust Heater
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Solution Overview
Problem
Existing honeycomb structures used for exhaust gas purification face challenges such as inefficient energy use, excessive current flow leading to circuit damage, and difficulty in loading catalysts onto metal heaters, as well as uneven temperature distribution and low energy efficiency when used as both catalyst carriers and heaters.
Innovation Solution
A honeycomb structure made of silicon carbide with a central region having lower electrical resistivity than the outer peripheral region, allowing for controlled current flow and efficient energy use, combined with a manufacturing method involving cordierite and carbon particles to create a gradient in electrical resistivity, enabling effective heat generation and catalyst loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metal heater is used to raise exhaust gas temperature, then the catalyst temperature can be raised, but excessive current flows causing power source circuit damage
Solution Approach 1:
The patent changes the electrical resistivity parameter of the heater material from metal (low resistivity) to ceramic material (high resistivity), which reduces current flow while maintaining heating capability. This parameter change directly resolves the contradiction between achieving sufficient catalyst temperature and preventing excessive current flow.
Solution Approach 2:
The patent uses composite ceramic materials with specific electrical resistivity characteristics to create a heater that combines both heating functionality and electrical resistance properties, eliminating the need for separate metal heater elements and reducing current flow.
2Temperature
If a metal heater is used, then heating function is achieved, but catalyst cannot be easily loaded onto the heater
Solution Approach 1:
The ceramic heater structure serves multiple functions: it provides heating capability, acts as a catalyst carrier substrate, and offers structural integrity. By making the heater itself capable of supporting catalyst, the patent eliminates the need for separate catalyst loading steps and metal heater components.
Solution Approach 2:
The patent merges the heater function and catalyst carrier function into a single integrated ceramic structure. The heater body itself becomes the catalyst support, combining two previously separate functions into one component, which simplifies manufacturing and catalyst loading.
3Temperature
If a ceramic honeycomb structure is used as heater, then even heat generation is achieved, but energy efficiency can be improved
Solution Approach 1:
The patent applies different electrical resistivity characteristics to different regions of the honeycomb structure, with higher resistivity in the central region and lower resistivity in the outer peripheral region. This local quality differentiation optimizes current distribution and heat generation efficiency across different areas of the structure.
Solution Approach 2:
The patent changes the electrical resistivity parameter spatially across the honeycomb structure, creating a gradient from central to peripheral regions. This parameter variation allows for optimized energy efficiency while maintaining even temperature distribution throughout the structure.
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 structure effectively uses applied voltage for exhaust gas treatment with reduced energy consumption and improved catalyst loading, preventing circuit damage and enhancing purification efficiency while maintaining even heat distribution.
Implementation Method 1
a honeycomb structure which is a catalyst carrier and also functions as a heater when a voltage is applied thereto and which can reduce energy when the voltage is applied thereto to purify an exhaust gas
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
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 reduce energy when the voltage is applied thereto to purify an exhaust gas. A honeycomb structure 100 includes a tubular honeycomb structure body 4 having porous partition walls 1 to define and form a plurality of cells 2 and an outer peripheral wall 3, and a pair of electrodes 21 disposed on a side surface 5 of the honeycomb structure body 4. An electrical resistivity of the honeycomb structure body 4 is from 1 to 200 Ωcm, each of the pair of electrodes 21 is formed into a band-like shape extending in an extending direction of the cells 2 of the honeycomb structure body 4, one electrode 21 in the pair of electrodes 21 is disposed on a side opposite to the other electrode 21 in the pair of electrodes 21 via a center of the honeycomb structure body 4, the honeycomb structure body 4 has a central region 6 and an outer peripheral region 7, and an electrical resistivity of the central region 6 is lower than an electrical resistivity of the outer peripheral region 7.