CO2 Gas Sensor Electrode Degradation Detection and Correction
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Solution Overview
Problem
The third inner electrode in gas sensors used to oxidize carbon monoxide degrades over time, leading to a decrease in the accuracy of carbon dioxide concentration measurement.
Innovation Solution
A gas sensor configuration with a control device that performs pump cell control processing to oxidize hydrogen and carbon monoxide, includes a third inner electrode degradation determination processing based on voltage and pump current measurements, and corrects carbon dioxide concentration measurements to account for electrode degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the third inner electrode is used to oxidize carbon monoxide continuously, then the carbon dioxide concentration measurement can be performed, but the electrode degrades over time leading to decreased measurement accuracy
Solution Approach 1:
The control device performs preliminary degradation determination by measuring voltage and pump current before the electrode completely degrades. This allows proactive detection and correction of degradation trends, maintaining measurement accuracy while enabling continuous operation.
Solution Approach 2:
The system continuously monitors voltage and pump current parameters to detect electrode degradation. Based on this feedback, the control device adjusts measurements or triggers warnings, maintaining accurate carbon dioxide concentration measurements despite ongoing electrode wear.
2Measurement precision
If degradation determination processing is performed frequently, then electrode degradation can be monitored accurately, but the processing load increases
Solution Approach 1:
The control device performs degradation determination at specific periodic intervals rather than continuously. This balances the need for monitoring accuracy with processing load management, executing measurements at optimal times when degradation is most detectable.
Solution Approach 2:
The system monitors changes in voltage and pump current parameters to detect degradation. By tracking parameter changes over time rather than performing complex analyses continuously, the system achieves accurate degradation detection with reduced processing requirements.
3Reliability
If the third inner electrode degrades, then measurement accuracy decreases, but replacing the electrode requires sensor replacement
Solution Approach 1:
The control device performs self-diagnosis by monitoring voltage and pump current to detect electrode degradation. This self-monitoring capability allows the system to track electrode condition without external intervention, enabling proactive maintenance decisions.
Solution Approach 2:
The patent replaces physical electrode replacement with an electrical monitoring and correction system. By using voltage and current measurements to detect and compensate for degradation, the system substitutes mechanical replacement with electronic diagnosis and correction.
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 sensor accurately determines and corrects for third inner electrode degradation, maintaining measurement accuracy by reducing processing load and minimizing the impact of carbon dioxide concentration changes.
Implementation Method 1
an element body having an oxygen-ion-conductive solid electrolyte layer
Implementation Method 2
oxygen is pumped from around the second outer electrode to around the second inner electrode by controlling the second pump cell, thereby oxidizing hydrogen generated by the reduction of water in the first chamber in the second chamber
Data Source
AI summary
A gas sensor includes a sensor element and a control device, and configured to measure a carbon dioxide concentration in a measurement gas, wherein: the sensor element includes an element body, a first pump cell, a second pump cell, a third pump cell including a third inner electrode, a reference electrode, and the control device performs a third inner electrode degradation determination processing for determining degradation of the third inner electrode based on a third voltage between third inner electrode and reference electrode during execution of first and second pump cell control processing and during stoppage of third pump cell control processing, and based on the third pump current flowing through the third pump cell during execution of the first to third pump cell control processing.