Electrically Heated Catalyst Comb Electrode Fixation
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Solution Overview
Problem
The existing electrically heated catalyst devices with comb-shaped electrodes experience local cracking in fixation layers due to thermal stress from repeated current flow, leading to non-uniform heating and potential conductivity issues.
Innovation Solution
The electrodes are fixed with equal contact lengths on rectangular fixation layers, where the edges of the wire portions face the first sides and are orthogonal to the second sides, reducing stress concentration and preventing excessive thermal stress, and the corners are made roundish to minimize crack generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If comb-shaped electrodes are fixed on the carrier via fixation layers, then current can flow through the carrier to heat it, but cracks may be generated locally in the fixation layers due to thermal stress from repeatedly flowed current
Solution Approach 1:
The invention uses a rectangular fixation layer instead of a circular one, creating an asymmetric geometry that allows equal contact lengths with opposite edges of the wire portion. This asymmetric design enables stress distribution across the structure, preventing localized stress concentration that would otherwise occur at specific points in a circular configuration.
Solution Approach 2:
The invention applies different geometric properties to different parts of the fixation layer. The rectangular shape provides equal contact lengths at opposite edges, while the roundish corners provide stress relief at critical locations. This localized optimization of geometry addresses the specific stress distribution requirements of the electrode fixation system.
2Ease of operation
If wire portions are fixed greatly displaced from the center of circular fixation layers, then contact lengths with opposite edges become different, but this generates excessive stress in regions with longer contact length
Solution Approach 1:
The rectangular fixation layer provides an asymmetric geometry that maintains equal contact lengths at opposite edges even when the wire portion is displaced from the center. This allows flexible electrode positioning without generating excessive stress, as the rectangular shape ensures uniform stress distribution across all contact regions.
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 ensures uniform heating of the catalyst even with repeated current flow, suppressing crack formation in the fixation layers and maintaining conductivity, thereby ensuring consistent performance.
Implementation Method 1
the carrier is heated with the current flowing therethrough via the comb-shaped electrodes
Data Source
Figure 1A~1B
Figure 2~3
Figure 4A~4B
AI summary
Provided is an electrically heated catalyst device that can uniformly heat a catalyst via comb-shaped electrodes even when current is repeatedly made to flow through the electrodes. An electrically heated catalyst device 1 includes a carrier 10 having a metal catalyst supported thereon, a pair of comb-shaped electrodes 5 each having wire portions 52, a base layer 4 between each comb-shaped electrode 5 and the carrier 10, and a fixation layer 6 for fixing each wire portion 52 on the base layer 4. The fixation layer 6 is rectangular in shape when the outer peripheral surface 10b of the carrier 10 is seen from a direction orthogonal to the central axis CL of the carrier 10 along the longitudinal direction D1 of the device 1. A pair of opposite first sides 61a and 61b of the fixation layer 6 are parallel with the extending direction D3 of each wire portion 52 on the opposite sides thereof, and a pair of second sides 62a and 62b coupling opposite ends of the first sides 61a and 61b are orthogonal to the extending direction D3 of each wire portion 52.