Electric Heating Catalyst Support with Segmented Base Layers
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Solution Overview
Problem
The existing electric heating catalyst support systems experience cracks in the base layers due to temperature differences, leading to peeling and inhibition of current flow, especially during vehicle vibrations.
Innovation Solution
The support system incorporates a honeycomb structure with strategically arranged and spaced base layers, ensuring electrical connection between electrode layers and metal electrode portions, with a specific pitch and diameter relationship to alleviate thermal expansion differences and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base layers are formed on the entire area where metal electrodes are fixed to ensure sufficient electrical contact, then electrical contact performance is improved, but temperature difference occurs between fixed and non-fixed base layer areas, generating cracks and peeling
Solution Approach 1:
The base layer is segmented into multiple discrete base layer portions rather than forming a continuous layer. Each base layer portion is positioned at specific locations where metal electrode portions are fixed to the electrode layer, creating independent contact points that maintain electrical conductivity while avoiding the temperature differential stresses that cause cracking in continuous layers.
Solution Approach 2:
The base layer structure transitions from uniform continuity to localized presence, with base layer portions appearing only at specific locations where electrical contact is needed. This local quality approach concentrates the electrical contact function at discrete points while eliminating the harmful thermal expansion differences that occur in continuously formed base layers.
2Stress or pressure
If base layers are formed to relax thermal expansion difference between electrode layer and metal electrode, then thermal stress is reduced, but temperature difference between fixed and non-fixed areas causes cracking
Solution Approach 1:
The base layer is divided into multiple separate base layer portions positioned at discrete locations rather than forming a continuous structure. This segmentation allows each portion to independently accommodate thermal expansion at its local metal electrode contact point while avoiding the creation of large temperature differentials that cause cracking in continuous base layers.
Solution Approach 2:
The base layer portions act as intermediary elements that locally mediate the thermal expansion difference between the electrode layer and metal electrode portions. By providing this stress-relief function only at discrete contact points rather than across the entire surface, the structure avoids the cracking problem while maintaining thermal compatibility where needed.
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
This configuration effectively suppresses the generation of cracks in the base layers, maintaining electrical contact and preventing peeling, while allowing for efficient heat generation and purification of exhaust gases.
Implementation Method 1
forming a base layer between an electrode layer and a metal electrode for relaxing a difference in thermal expansion
Implementation Method 2
electrodes are disposed on a honeycomb structure made of conductive ceramics and the honeycomb structure itself generates heat by electric conduction
Implementation Method 3
the honeycomb structure itself generates heat by electric conduction
Data Source
AI summary
A support for an electric heating type catalyst includes: a honeycomb structure having: porous partition walls extending through the honeycomb structure from an inflow end face to an outflow end face to define a plurality of cells forming a through channel; and an outer peripheral wall located at the outermost periphery; a pair of electrode layers disposed on the outer peripheral wall of the honeycomb structure; and a pair of electrode portions. Each of the electrode layers is formed in a strip shape extending in an extending direction of the cell of the honeycomb structure. In a cross section orthogonal to the extending direction of the cell, one electrode layer of the pair of electrode layers is disposed on a side opposite to the other electrode layer across a center of the honeycomb structure. Each of the electrode layers is electrically connected to each of the electrode portions via two or more base layers, and the base layers have conductivity and are spaced apart from each other. Each of the electrode portions includes two or more electrodes, and each of the electrodes is fixed to outer surfaces of the base layers.