Gas Sensor Oxygen Ion Conduction Accuracy
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Solution Overview
Problem
Conventional gas sensors face a reduction in oxygen concentration around the reference electrode, leading to decreased accuracy in detecting specific gas concentrations, particularly when the measurement-object gas enters the reference gas introduction space.
Innovation Solution
A gas sensor design that includes an oxygen ion conductive solid electrolyte layer, measurement and reference electrodes, and a reference gas adjustment device, where the ratio of limiting currents A/B is greater than or equal to 0.005 to ensure adequate oxygen pumping from the measurement-object gas-side electrode to the reference electrode, maintaining optimal oxygen concentration and reducing diffusion resistance imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oxygen is pumped into the surroundings of the reference electrode to compensate for oxygen concentration reduction, then the accuracy of detection is improved, but the oxygen concentration in the reference gas may still be reduced if the pumping amount is insufficient
Solution Approach 1:
The patent introduces a feedback mechanism where the electromotive force generated by the reference electrode and measurement electrode is detected, and this detection signal is fed back to control the oxygen pumping current. This ensures that the oxygen concentration around the reference electrode is automatically maintained at the optimal level, preventing both deficiency and excess accumulation.
Solution Approach 2:
The patent dynamically adjusts the oxygen pumping current based on the detected electromotive force, which reflects the oxygen concentration status. By changing the pumping current parameter in response to real-time conditions, the system maintains optimal oxygen concentration around the reference electrode.
2Productivity
If the measurement-object gas introduction section has low diffusion resistance to allow sufficient oxygen supply, then the oxygen pumping efficiency is improved, but the reference gas may be contaminated by measurement-object gas
Solution Approach 1:
The patent applies different diffusion resistance characteristics to different sections: the measurement-object gas introduction section has lower diffusion resistance to facilitate oxygen supply to the measurement electrode, while the reference gas introduction section has higher diffusion resistance to prevent contamination. This local differentiation resolves the contradiction between pumping efficiency and gas purity.
3Reliability
If the reference gas introduction section has high diffusion resistance to prevent measurement-object gas contamination, then the reference gas purity is improved, but the oxygen supply to the reference electrode may be insufficient
Solution Approach 1:
The patent introduces an intermediary oxygen pumping mechanism that actively transports oxygen from the measurement-object gas side to the reference electrode side through the solid electrolyte layer. This intermediary pumping action overcomes the high diffusion resistance of the reference gas introduction section, ensuring sufficient oxygen supply while maintaining reference gas purity.
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 compensates for oxygen concentration reductions around the reference electrode, maintaining accurate detection of specific gas concentrations by ensuring sufficient oxygen supply and appropriate resistance values, thereby enhancing the sensor's accuracy and reliability.
Implementation Method 1
an element body having an oxygen ion conductive solid electrolyte layer
Implementation Method 2
a reference gas adjustment device that carries an oxygen pumping current between the reference electrode and the measurement-object gas-side electrode, and pumps oxygen from surroundings of the measurement-object gas-side electrode into surroundings of the reference electrode
Implementation Method 3
a detection device that detects the specific gas concentration in the measurement-object gas based on an electromotive force generated between the reference electrode and the measurement electrode
Data Source
AI summary
A gas sensor includes an element body having an oxygen ion conductive solid electrolyte layer and internally provided with a measurement-object gas flow section that introduces a measurement-object gas and allows the gas to flow; a measurement-object gas-side electrode disposed in a portion of the element body, the portion being exposed to the measurement-object gas; and a reference electrode disposed inside of the element body. Let A [μA] be a limiting current when oxygen is pumped from the surroundings of the measurement-object gas-side electrode to the surroundings of the reference electrode with the measurement-object gas introduction section, and B [μA] be a limiting current when oxygen is pumped from the surroundings of the reference electrode to the surroundings of the measurement-object gas-side electrode with the reference gas introduction section, then a ratio A/B is greater than or equal to 0.005.