Gas Sensor Lead Layout for Reference Gas Contamination Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas sensors using oxygen-ion conductive solid electrolyte ceramics face measurement accuracy deterioration due to contaminated gases generated in the reference gas space, especially under rich gas atmospheres, which affect both the reference and measurement electrodes.
Innovation Solution
The gas sensor incorporates a configuration with oxygen partial pressure adjustment internal spaces, pump electrodes, and insulating layers for electrode leads, along with pump cells to maintain constant oxygen concentration and reduce diffusion resistance, thereby minimizing the impact of contaminated gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the reference gas space is sealed with a rubber plug containing through holes for lead lines, then the sensor can be manufactured simply and air can enter as reference gas, but contaminated gas generated during high-temperature operation can enter through gaps between the through holes and lead lines, deteriorating measurement accuracy
Solution Approach 1:
The patent introduces a reference gas introduction space as an intermediary chamber between the reference gas space and the measurement electrode. This space is sealed by a solid electrolyte layer, creating a barrier that prevents contaminated gas from reaching the measurement electrode while still allowing reference gas to be supplied to the reference electrode for maintaining reference potential.
Solution Approach 2:
The patent divides the internal structure into separate functional spaces: a reference gas space for housing the reference electrode, and a reference gas introduction space that is sealed and communicates with the measurement electrode side. This segmentation isolates the measurement electrode from contaminated reference gas, resolving the contradiction between manufacturing simplicity and measurement accuracy.
2Ease of manufacture
If the sensor element includes porous electrode leads for electrical connection, then cost is reduced and flexibility is improved, but diffusion resistance decreases allowing contaminated gas to reach the measurement electrode more easily
Solution Approach 1:
The sealed reference gas introduction space acts as an intermediary barrier that prevents contaminated gas from reaching the measurement electrode through the porous electrode leads. The solid electrolyte layer sealing this space blocks gas diffusion while still allowing the porous leads to provide electrical connection, thus maintaining cost benefits while preventing contamination.
3Reliability
If the sensor is used under high-temperature exhaust gas atmosphere, then the heater can maintain sensor element temperature for proper operation, but oil content volatilization and rubber plug gas generation contaminate the reference gas
Solution Approach 1:
The patent extracts the reference gas introduction function from the reference gas space by creating a separate, sealed reference gas introduction space that is isolated from the contaminated reference gas space. This allows the sensor to operate reliably under high-temperature conditions while preventing contaminated gas from affecting the measurement electrode.
Solution Approach 2:
The sealed reference gas introduction space serves as an intermediary barrier between the contaminated reference gas environment and the measurement electrode. This intermediate sealed chamber prevents harmful volatile substances from reaching the measurement electrode while allowing proper sensor operation at high temperatures.
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 design effectively suppresses temporary output fluctuations and maintains measurement accuracy by preventing contaminated gases from reaching the measurement electrode, even when used in high-temperature environments with potential gas contamination.
Implementation Method 1
a sensor element (101) including an elongated planar base part (101c) formed of an oxygen-ion conductive solid electrolyte
Implementation Method 2
when a pump current is applied to a pump electrode (22, 51), oxygen in a measurement gas (exhaust gas) is removed
Data Source
AI summary
A casing of a gas sensor having a reference gas space therein includes: an outer tube into which an end portion of a sensor element protrudes; and a seal member fit into an end portion of the outer tube to seal the reference gas space, the sensor element includes: a first electrode lead portion including a first electrode lead to electrically connect an outside and at least one inner electrode and a first lead insulating layer covering the first electrode lead; and a second electrode lead portion including a second electrode lead that can electrically connect the outside and a measurement electrode and a second lead insulating layer covering the second electrode lead, and A/B<1.00, where A (cm−1) is diffusion resistance of the first electrode lead portion, B (cm−1) is diffusion resistance of the second electrode lead portion.