Gas Sensor Oxygen Ion Electrolyte High Concentration Measurement
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Solution Overview
Problem
Current gas sensors face challenges in accurately measuring water vapor and carbon dioxide concentrations in exhaust gases from internal combustion engines, particularly due to susceptibility to humidity and temperature changes, and complex configurations requiring complicated calibration.
Innovation Solution
A gas sensor utilizing an oxygen-ion conductive solid electrolyte with a specific configuration of diffusion control parts and electrochemical pumping cells to decompose water vapor and carbon dioxide, allowing for accurate measurement of their concentrations based on current flow, independent of the presence of both components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a carbon dioxide sensor is designed to increase specificity to carbon dioxide, then sensitivity to water vapor decreases, but the sensor becomes susceptible to temperature changes
Solution Approach 1:
The sensor divides the measurement function into separate cells: one cell measures carbon dioxide with high specificity while another cell measures water vapor, allowing independent optimization of each measurement without cross-interference. This segmentation resolves the contradiction by enabling CO2 specificity improvement without necessarily compromising temperature stability.
Solution Approach 2:
The patent employs multiple cells with different operating parameters and characteristics. By changing parameters such as cell geometry, electrode configuration, and measurement conditions across different cells, the system achieves high CO2 specificity in one cell while maintaining temperature stability through the combined measurements from multiple cells.
2Adaptability or versatility
If a sensor apparatus is designed to measure both water vapor and carbon dioxide concentrations, then measurement capability is improved, but the configuration becomes complex and calibration becomes complicated
Solution Approach 1:
The measurement function is segmented into separate cells, each dedicated to measuring one component (water vapor or carbon dioxide). This segmentation simplifies the overall system design compared to using a single multi-functional cell, as each cell can be independently optimized and calibrated without affecting the other measurements.
Solution Approach 2:
Multiple cells operate within a single sensor apparatus, providing universal measurement capability for both water vapor and carbon dioxide. This multi-functionality is achieved through a modular cell structure that can be replicated and combined, rather than requiring entirely separate measurement systems.
3Measurement precision
If diffusion resistance is increased to improve measurement accuracy, then measurement precision improves, but the response time and measurement speed decrease
Solution Approach 1:
The gas distribution is segmented into multiple cells with different diffusion resistance characteristics. By distributing the measurement function across cells with varying diffusion properties, the system achieves both high measurement accuracy (through sufficient diffusion resistance) and fast response (through parallel measurement channels that compensate for individual cell response times).
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
Enables accurate measurement of water vapor and carbon dioxide concentrations up to high ranges, irrespective of whether the measurement gas contains both components, with improved sensitivity and reduced susceptibility to temperature changes, facilitating practical application in exhaust gas monitoring.
Implementation Method 1
a sensor element (101) having an oxygen-ion conductive solid electrolyte
Implementation Method 2
a main electrochemical pumping cell (21)... a first measuring electrochemical pumping cell (50)... a second measuring electrochemical pumping cell (47)
Implementation Method 3
a first diffusion control part (11)... a second diffusion control part (30)... wherein a diffusion resistance from the gas inlet (10) to the first internal space (20) is 370 /cm or more and 1000 /cm or less
Data Source
Figure 1
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AI summary
Provided is a gas sensor (100) capable of accurately obtaining the concentrations of water vapor and carbon dioxide in up to a high concentration range. The diffusion resistance from a gas inlet (10) to a first internal space (20) is 370 /cm to 100 /cm. The oxygen partial pressure of the first internal space (20) is adjusted to 10-12 atm to 10-30 atm. A first measuring pumping cell (50) adjusts the oxygen partial pressure of a second internal space (40) such that hydrogen generated by the decomposition of water vapor selectively burns. A second measuring pumping cell (47) adjusts the oxygen partial pressure on the surface of a second measuring internal electrode (44) such that all of the carbon monoxide generated by the decomposition of carbon dioxide burns on the surface. The concentrations of water vapor and carbon dioxide are based on the magnitude of a current flowing between the first (51) or second (44) measuring internal electrode and the external electrode (23).