Oxygen Sensor Offset Heater Design
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Solution Overview
Problem
The existing oxygen concentration detecting elements suffer from thermal stress-induced cracks due to overlapping materials with different coefficients of thermal expansion, leading to reduced yield and increased production costs due to the need for thicker heater insulating layers and repeated printing.
Innovation Solution
The oxygen concentration detecting element features a heater and oxygen detecting unit arranged in an offset position on the base member's surface, with a stress damping layer and reduced heater insulating layer thickness, preventing thermal stress and improving lead yield and reducing printing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heater pattern and oxygen detecting unit are overlaid one another via heater insulating layer, then insulation between heater and oxygen detecting unit is achieved, but thermal stress causes separation and cracks due to different coefficients of thermal expansion
Solution Approach 1:
The patent transitions from a vertical stacking arrangement (heater pattern directly over oxygen detecting unit) to a radial offset arrangement where the oxygen detecting unit is positioned at a different radial location from the heater pattern. This dimensional change eliminates thermal stress while maintaining insulation through the base member structure itself.
Solution Approach 2:
The patent removes the heater insulating layer from the structure by eliminating the need for it through the offset arrangement. The base member itself provides sufficient insulation when the components are radially separated, thereby extracting the problematic insulating layer that caused thermal stress.
2Reliability
If heater insulating layer thickness is increased to ensure insulation, then insulation between heater pattern and oxygen detecting unit is improved, but leads must extend along larger steps causing break and reduced yield
Solution Approach 1:
The patent moves the insulation function from the vertical dimension (thicker heater insulating layer) to the radial dimension (offset positioning). This eliminates large steps that would require long leads, thereby improving lead yield while maintaining insulation through radial separation.
3Reliability
If heater insulating layer thickness is increased through repeated printing, then insulation between heater pattern and oxygen detecting unit is improved, but manufacturing cost increases
Solution Approach 1:
The patent solves the insulation problem by moving to a radial offset arrangement rather than increasing vertical thickness through repeated printing. This single-step manufacturing approach reduces both production time and cost while achieving the required insulation.
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 prevents cracks and improves lead yield by avoiding thermal stress and reducing production costs through minimized printing and insulation thickness, while maintaining accurate oxygen concentration detection.
Implementation Method 1
a heater (3) disposed on an outer surface (2A) of the base member (2), the heater (3) being adapted to generate heat upon being energized
Implementation Method 2
When there is a difference in oxygen concentration between the inner and outer surfaces of solid electrolyte layer 102, oxygen ions are transmitted through solid electrolyte layer 102 to produce electromotive force between reference electrode 104 and detecting electrode 105
Implementation Method 3
a stress damping layer (8) disposed between the outer surface (2A) of the base member (2) and an inner surface of the reference electrode (6)
Data Source
AI summary
An oxygen concentration detecting element including a base member made of an electrically insulating material, a heater disposed on an outer surface of the base member, the heater being adapted to generate heat upon being energized, and an oxygen detecting unit disposed in an offset position on the outer surface of the base member in which the oxygen detecting unit is prevented from overlapping with the heater, the oxygen detecting unit including a solid electrolyte layer and a pair of electrodes between which the solid electrolyte layer is disposed.