Gas Sensor Electrode Volume Ratio for Fast Light-Off Stability
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Solution Overview
Problem
Existing gas sensors with smaller measurement electrodes tend to have shorter light-off times but are more prone to deterioration, leading to longer light-off times over time.
Innovation Solution
The sensor element design includes specific volume and area ratios for the measurement electrode within the measurement chamber, along with the use of a porous measurement electrode and multiple pump cells to adjust oxygen concentration, thereby suppressing electrode deterioration and maintaining efficient oxygen pumping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the volume of the measurement electrode is reduced, then the light-off time is shortened, but the measurement electrode is more likely to deteriorate
Solution Approach 1:
The invention optimizes the volume ratio parameter of the measurement electrode within a specific range (0.05 ≤ Fv ≤ 0.21) to achieve the best balance between light-off time and electrode durability. This parameter optimization allows the electrode to be small enough for fast response while maintaining sufficient volume to prevent deterioration during operation.
2Loss of time
If the volume of the measurement electrode is reduced, then the light-off time is shortened, but the measurement precision may deteriorate
Solution Approach 1:
The invention determines the optimal volume ratio range (0.05 ≤ Fv ≤ 0.21) that simultaneously satisfies fast light-off time and adequate measurement precision. The lower bound ensures sufficient electrode volume for accurate gas concentration detection, while the upper bound maintains short light-off time for rapid response.
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 suppresses the light-off time from becoming longer while minimizing measurement electrode deterioration, ensuring accurate and reliable gas concentration detection.
Implementation Method 1
a measurement pump cell including a measurement electrode provided in a measurement chamber that is located downstream of the oxygen concentration adjustment chamber in the measurement-object gas flow section, and adjusting an oxygen concentration in the measurement chamber
Implementation Method 2
an adjustment pump cell including an inner adjustment electrode provided in an oxygen concentration adjustment chamber of the measurement-object gas flow section, and being configured to adjust an oxygen concentration in the oxygen concentration adjustment chamber
Implementation Method 3
an element body including an oxygen-ion-conductive solid electrolyte layer
Data Source
AI summary
A sensor element for detecting a concentration of a specific gas in a measurement-object gas, the sensor element includes: an element body including an oxygen-ion-conductive solid electrolyte layer, and including a measurement-object gas flow section inside that introduces the measurement-object gas and allows the measurement-object gas to flow through; an adjustment pump cell including an inner adjustment electrode provided in an oxygen concentration adjustment chamber of the measurement-object gas flow section; and a measurement pump cell including a measurement electrode provided in a measurement chamber that is located downstream of the oxygen concentration adjustment chamber in the measurement-object gas flow section; wherein, letting Ve [mm3] be a volume of the measurement electrode, and Vr [mm3] be a volume of the measurement chamber, and defining a volume ratio as Fv=Ve/(Vr−Ve), 0.05≤Fv≤0.21 is satisfied.