Multi-Pump Gas Sensor for Electrode Degradation Detection
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Solution Overview
Problem
The second inner electrode in gas sensors used for measuring water vapor and carbon dioxide concentrations degrades over time, leading to a decrease in measurement accuracy.
Innovation Solution
A gas sensor configuration with multiple pump cells and a control device that performs specific control processing to measure water and carbon dioxide concentrations, and includes a degradation determination processing to detect electrode degradation by monitoring voltage changes during pump cell operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the second inner electrode is used to oxidize hydrogen in the gas sensor, then water vapor concentration measurement is enabled, but the electrode degrades over time causing measurement accuracy to decrease
Solution Approach 1:
The control device monitors the voltage between the third inner electrode and reference electrode during pump cell operations. When voltage exceeds a predetermined threshold, indicating second inner electrode degradation, the system provides feedback to detect and report the degradation state, enabling timely maintenance or replacement to preserve measurement accuracy
Solution Approach 2:
The system performs preliminary voltage monitoring during normal operation to detect degradation before it significantly impacts measurement accuracy. By continuously checking voltage thresholds during pump cell operations, the system can identify electrode degradation early and take preventive measures
2Adaptability or versatility
If multiple pump cells are added to measure both water and carbon dioxide concentrations, then measurement functionality is improved, but device complexity increases
Solution Approach 1:
The third inner electrode serves multiple functions: it acts as a measurement electrode for carbon dioxide concentration detection and as a reference electrode for voltage monitoring to detect second inner electrode degradation. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity while enhancing measurement versatility
Solution Approach 2:
The patent combines the reference electrode function with the third inner electrode, merging two functional roles into a single component. This integration allows the system to monitor degradation while maintaining measurement capability, reducing overall device complexity compared to having separate reference and measurement electrodes
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 allows for accurate determination of electrode degradation, maintaining measurement accuracy by preventing hydrogen and carbon monoxide oxidation inefficiencies, thereby ensuring reliable gas concentration measurements.
Implementation Method 1
an element body having an oxygen-ion-conductive solid electrolyte layer
Implementation Method 2
oxidizing hydrogen generated by the reduction of water in the first chamber in the second chamber
Implementation Method 3
a second inner electrode disposed in a second chamber located downstream of the first chamber
Implementation Method 4
oxidizing carbon monoxide generated by the reduction of carbon dioxide in the first chamber in the third chamber
Implementation Method 5
a third inner electrode disposed in a third chamber located downstream of the second chamber
Implementation Method 6
measuring the water concentration in the measurement gas based on a second pump current flowing through the second pump cell
Data Source
AI summary
A gas sensor includes a sensor element and a control device, and configured to measure a water concentration and/or a carbon dioxide concentration in a measurement gas, wherein: the sensor element includes an element body, a first pump cell, a second pump cell including a second inner electrode, a third pump cell, a reference electrode, and the control device performs a second inner electrode degradation determination processing for determining degradation of the second inner electrode based on whether or not an absolute value of a third voltage during execution of first and second pump cell control processing and during stoppage of third pump cell control processing falls within a predetermined high-voltage region.