Honeycomb PTC Heater Terminals for Uniform Heating Without Cracks
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Solution Overview
Problem
The integration of metal terminals over the entire circumference of a honeycomb structure in existing heater elements leads to thermal expansion differences, causing stress and cracks, resulting in non-uniform current and temperature distribution.
Innovation Solution
Divide the metal terminals into multiple partial electrodes that fit together circumferentially to alleviate stress and reduce the risk of cracking, ensuring even current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal terminals are integrally provided over the entire circumference of the honeycomb structure, then current distribution and temperature distribution become more uniform, but thermal expansion stress causes cracks in the honeycomb structure
Solution Approach 1:
The metal terminal is divided into multiple independent partial electrodes instead of being provided as a single integral structure. This segmentation reduces the thermal expansion stress concentrated on the honeycomb structure while maintaining current distribution uniformity through the coordinated arrangement of multiple partial electrodes.
2Reliability
If metal terminals are divided into multiple partial electrodes, then thermal expansion stress and cracking risk are reduced, but current distribution uniformity may deteriorate
Solution Approach 1:
Each partial electrode is positioned and dimensioned to provide locally optimized current distribution. The combination of multiple partial electrodes with specific geometries and arrangements achieves overall current uniformity while each individual electrode maintains lower stress on the honeycomb 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 solution effectively reduces stress-induced cracking and ensures uniform temperature and current distribution across the honeycomb structure, preventing interruptions and non-uniform heating.
Implementation Method 1
at least the partition walls being made of a material having a positive temperature coefficient (PTC) property
Implementation Method 2
a first metal terminal and a second metal terminal provided on the first electrode and the second electrode, respectively
Implementation Method 3
By spreading the current from the metal terminals by the electrodes and then allowing it to flow through the honeycomb structure
Data Source
AI summary
A heater element 1 includes: a honeycomb structure 10 having an outer peripheral wall 100 and partition walls 110, the partition walls 110 defining a plurality of cells 101a, each of the cells 101a extending from a first end face 10a to a second end face 10b of the honeycomb structure 10 to form a flow path, at least the partition walls 101 being made of a material having a positive temperature coefficient (PTC) property; a first electrode 11 and a second electrode 12 provided on the first end face 10a and the second end face 10b, respectively; and a first metal terminal 13 and a second metal terminal 14 provided on the first electrode 11 and the second electrode 12, respectively, wherein at least one of the first metal terminal 13 and the second metal terminal 14 has a plurality of partial electrodes 15.