Multi-Chamber Gas Sensor for Simultaneous NOx and CO2 Detection
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Solution Overview
Problem
Existing gas sensors cannot simultaneously detect the concentrations of NOx and carbon dioxide in a measurement-object gas.
Innovation Solution
A gas sensor comprising a sensor element with an oxygen-ion-conductive solid electrolyte layer, multiple pump cells, and a control apparatus that adjusts oxygen concentration to detect NOx and carbon dioxide concentrations based on measurement pump currents, and optionally water concentration, using electrochemical pumping cells to measure NOx and carbon dioxide reductions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a gas sensor uses a single measurement chamber with one electrode to detect gas concentration, then the device structure is simple, but it can only detect one type of gas concentration simultaneously
Solution Approach 1:
The measurement chamber is divided into multiple separate chambers (first measurement chamber for NOx detection and second measurement chamber for CO2 detection), with each chamber containing its own dedicated electrode. This segmentation allows simultaneous detection of multiple gas types while maintaining clear functional separation and measurement specificity.
Solution Approach 2:
The sensor element is designed with multi-functionality to simultaneously detect both NOx and CO2 concentrations using the same basic electrochemical pumping mechanism. The universal design allows a single sensor to perform multiple detection functions by incorporating multiple measurement chambers with different electrode configurations.
2Adaptability or versatility
If the sensor detects both NOx and CO2 concentrations simultaneously, then the measurement coverage is comprehensive, but the measurement precision for each gas may be affected by interference from the other gas
Solution Approach 1:
By separating the measurement chambers into distinct physical spaces with dedicated electrodes, the sensor eliminates cross-interference between NOx and CO2 detection. Each chamber independently processes its specific gas measurement, ensuring high precision for both gases simultaneously without signal contamination from the other gas type.
3Measurement precision
If the sensor structure includes multiple measurement chambers and pump cells, then the measurement capability is enhanced, but the device complexity increases
Solution Approach 1:
Multiple measurement chambers and pump cells are integrated into a single unified sensor element structure. The combined design allows simultaneous NOx and CO2 detection within one compact unit, enhancing measurement capability while avoiding the need for separate sensor devices. The integrated architecture shares common components such as the solid electrolyte layer and control system.
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 detects NOx and carbon dioxide concentrations, with the ability to also measure water concentration, by controlling oxygen concentration through pump cells and electrochemical processes, enhancing measurement accuracy.
Implementation Method 1
an element body including an oxygen-ion-conductive solid electrolyte layer
Implementation Method 2
a first measurement pump cell constituted by including an first inner measurement electrode disposed in a first measurement chamber... the first measurement pump cell being configured to pump out oxygen in the first measurement chamber
Implementation Method 3
the NOx in measurement-object gas is reduced in the periphery of a measurement electrode disposed in the measurement chamber
Data Source
AI summary
A gas sensor includes a sensor element including an element body, a first measurement pump cell, a second measurement pump cell, an adjustment pump cell, and a reference electrode; and a control apparatus, wherein the control apparatus detects a NOx concentration based on a first measurement pump current which flows when the oxygen produced due to reduction of NOx is pumped out, and the control apparatus detects a carbon dioxide concentration based on a second measurement pump current which flows when the oxygen produced due to reduction of carbon dioxide in a second measurement chamber is pumped out, and a change in a first measurement pump current which flows during execution of a adjustment pump control process and a first measurement pump control process when at least one of an adjustment voltage target value or a first measurement voltage target value is changed.