Gas sensor
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Solution Overview
Problem
Existing gas sensors experience measurement accuracy deterioration due to contaminated gases generated in the reference gas space, particularly under rich gas atmospheres, which affect the measurement electrodes and lead to output fluctuations.
Innovation Solution
The gas sensor incorporates a configuration with specific diffusion resistance ratios between electrode lead portions, including a measurement electrode lead portion and an outer pump electrode lead portion, to minimize the impact of contaminated gases on measurement accuracy by controlling the flow of contaminants through the electrode leads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous reference electrode lead is used to connect the reference electrode and electrode pad, then electrical connection is achieved, but contaminated gas can enter through the lead and reach the measurement electrode, causing measurement accuracy deterioration
Solution Approach 1:
The patent divides the electrode lead structure into multiple segments with different functions: a reference electrode lead portion and a measurement electrode lead portion. Each portion has specifically controlled diffusion resistance properties, allowing the reference electrode lead to be porous for electrical connection while the measurement electrode lead has higher diffusion resistance to block contaminated gas, thus resolving the contradiction between electrical connection reliability and measurement precision.
2Adaptability or versatility
If the sensor is used under a rich gas atmosphere at high temperature, then the sensor can operate in harsh environments, but contaminated gas is generated due to volatilization of oil content and rubber plug decomposition, which contaminates the reference gas and causes reference potential changes
Solution Approach 1:
The patent applies local quality by creating different diffusion resistance characteristics in different portions of the electrode lead structure. The reference electrode lead portion has lower diffusion resistance to allow controlled gas exchange, while the measurement electrode lead portion has higher diffusion resistance to specifically block contaminated gas. This localized differentiation allows the sensor to maintain measurement accuracy in harsh environments where contaminated gas is generated.
3Ease of manufacture
If the reference gas space is sealed with a grommet and lead lines, then the reference gas space is formed, but gaps between the through holes of the grommet and lead lines allow air to enter and become reference gas, which can be contaminated
Solution Approach 1:
The patent introduces the electrode lead portions as intermediary elements that mediate between the reference gas space and the measurement electrode. The measurement electrode lead portion acts as a diffusion resistance barrier that selectively controls gas flow, preventing contaminated gas from reaching the measurement electrode while still allowing the reference gas space to be effectively sealed through the grommet and lead line assembly.
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 effectively suppresses temporary output fluctuations and maintains measurement accuracy by ensuring that the ratio of diffusion resistances between electrode lead portions is optimized, thereby reducing the effect of contaminated gases on the sensor's performance.
Implementation Method 1
A/B≥0.001, where A (cm−1) is diffusion resistance of the outer pump electrode lead portion, B (cm−1) is diffusion resistance of the measurement electrode lead portion
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 out-of-space pump 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.