Porous Insulative Protection Layer for Gas Sensor Electrode Insulation
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Solution Overview
Problem
Water ingress into gas sensors due to exhaust gas condensation can lead to insulation failure between electrodes, causing short circuits and hindering gas measurement.
Innovation Solution
A gas sensor design featuring a gas-permeable, porous insulative protection layer on electrodes in the reference oxygen chamber, with a gap between the protection layers to prevent water seepage and maintain insulation, even under potential differences and high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-proofing measures are added to prevent water ingress, then reliability improves, but device complexity increases
Solution Approach 1:
The patent applies porous insulative protection layers made of porous ceramic material to the surfaces of electrodes in the reference oxygen chamber. These porous layers provide water-proofing functionality while maintaining electrical insulation, preventing water ingress that would cause short circuits between electrodes without requiring complex additional structures.
2Reliability
If insulative protection layers are made dense to improve insulation, then electrical insulation improves, but gas permeability deteriorates
Solution Approach 1:
The patent uses porous ceramic materials for the insulative protection layers, which inherently possess both electrical insulation properties and gas permeability. The porous structure allows exhaust gas to pass through while maintaining electrical insulation capabilities, resolving the contradiction between dense insulation and gas permeability.
Solution Approach 2:
The insulative protection layers are formed as composite structures combining insulative ceramic materials with porous characteristics. This composite approach enables simultaneous achievement of electrical insulation and gas permeability, as the porous ceramic composite provides both functions without compromise.
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
Prevents short circuits and ensures accurate gas measurement by containing water within the protection layer and gap, reducing sublimation-induced scattering and conductive impurity elution, thus maintaining reliable electrical insulation.
Implementation Method 1
a gas-permeable, porous insulative protection layer which is formed on at least one of the two electrodes disposed in the reference oxygen chamber... with a gap present therebetween
Implementation Method 2
a gas-permeable, porous insulative protection layer
Implementation Method 3
containing water within the protection layer and gap
Implementation Method 4
reducing sublimation-induced scattering and conductive impurity elution
Implementation Method 5
maintaining reliable electrical insulation
Data Source
AI summary
In a gas sensor element of a gas sensor, reference oxygen chamber (113) assumes the shape of a rectangular parallelepiped. A reference electrode (111) is disposed on a surface of a third solid electrolyte body (73) which is exposed to the reference oxygen chamber (113). A second outer electrode (117) is disposed opposite the reference electrode, on a surface of a second solid electrolyte body (77) which is exposed to the reference oxygen chamber. Further, a porous, insulative protection layer (165) is formed so as to cover the entire surface of the second outer electrode. A gap (167) is present between the reference electrode and the insulative protection layer. The thickness of the gap is greater than that of the insulative protection layer.