Gas Sensor Reference-Gas Path With Preliminary Chambers
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Solution Overview
Problem
The change in oxygen concentration around the reference electrode in gas sensors can affect the detection accuracy of specific gas concentrations, particularly due to the ingress of measurement-object gas into the reference-gas introduction space.
Innovation Solution
Incorporating one or more preliminary chambers with lower diffusion resistance than the reference-gas flow path, and at least part of the reference-gas flow path composed of a porous body, to act as a buffer against changes in oxygen concentration, ensuring the preliminary chambers do not directly communicate with the outside of the element body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measurement-object gas is introduced into the measurement-object gas flow section, then the specific gas concentration can be detected, but the oxygen concentration around the reference electrode may change due to gas ingress into the reference-gas introduction space
Solution Approach 1:
A preliminary chamber is introduced as an intermediary between the reference-gas introduction space and the reference electrode. This preliminary chamber has lower diffusion resistance than the reference-gas flow path, allowing it to act as a buffer that stabilizes the oxygen concentration around the reference electrode while still permitting reference gas to reach the electrode. The preliminary chamber absorbs concentration fluctuations without directly communicating with the outside environment, thus maintaining measurement stability.
Solution Approach 2:
The reference-gas flow path is constructed using a porous body that provides controlled diffusion resistance. The porous structure allows reference gas to permeate through to the reference electrode while regulating the flow rate and preventing direct communication between the preliminary chamber and the outside. This porous configuration ensures stable oxygen concentration delivery to the reference electrode.
2Stability of the object's composition
If oxygen is pumped in around the reference electrode to counteract oxygen concentration changes, then oxygen concentration can be maintained, but excessive or insufficient pumping causes oxygen concentration changes
Solution Approach 1:
The preliminary chamber serves as a pre-buffer that cushions against oxygen concentration changes before they reach the reference electrode. By providing a chamber with lower diffusion resistance that is filled with reference gas, the system pre-compensates for potential oxygen concentration fluctuations, reducing or eliminating the need for active oxygen pumping and its associated measurement errors.
3Ease of operation
If the reference-gas introduction space directly communicates with the outside, then reference gas can be easily introduced, but measurement-object gas can enter and change oxygen concentration
Solution Approach 1:
The preliminary chamber acts as an intermediary that decouples the direct communication between the outside environment and the reference electrode. It allows reference gas to be introduced while preventing measurement-object gas from directly reaching the reference electrode, thus maintaining oxygen concentration stability without complicating the reference gas introduction process.
Solution Approach 2:
The porous body in the reference-gas flow path provides selective permeability, allowing reference gas to pass through while restricting the ingress of measurement-object gas. This porous structure maintains ease of reference gas introduction while protecting the reference electrode environment from contamination.
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 the change in oxygen concentration around the reference electrode, enhancing the accuracy of gas concentration detection by maintaining a stable reference gas environment.
Implementation Method 1
one or more preliminary chambers which are disposed in the middle of the reference-gas flow path and have a diffusion resistance lower than that of the reference-gas flow path
Implementation Method 2
at least part of the reference-gas flow path is composed of a porous body so that any of the one or more preliminary chambers does not directly communicate with the outside of the element body
Data Source
AI summary
A sensor element for detecting a specific gas concentration in a measurement-object gas includes: an element body provided with a measurement-object gas flow section therein, the measurement-object gas flow section introducing the measurement-object gas and causing the measurement-object gas to flow therethrough; a reference electrode disposed inside the element body; and a reference-gas introduction section that causes a reference gas to flow to the reference electrode, wherein the reference-gas introduction section has a reference-gas flow path, and one or more preliminary chambers which are disposed in a middle of the reference-gas flow path, and have a diffusion resistance lower than a diffusion resistance of the reference-gas flow path, and at least part of the reference-gas flow path is composed of a porous body so that any of the one or more preliminary chambers does not directly communicate with an outside of the element body.