Gas Sensor Oxygen Control NOx Measurement
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Solution Overview
Problem
Current gas sensors are unable to accurately measure the concentrations of NO, NO2, and NH3 in exhaust gases, particularly in the presence of oxygen, and struggle with long-term stability and differentiation between these components.
Innovation Solution
A gas sensor with a solid electrolyte structure that includes an oxygen concentration adjustment chamber and a measurement chamber, utilizing multiple conditions and relational expressions to calculate the concentrations of NO, NO2, and NH3 by controlling oxygen concentration and temperature, allowing for precise measurement through electrochemical pump cells and sensor outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional NOx sensors convert all NO2 into NO for measurement, then total NOx concentration can be measured, but the ability to distinguish between NO and NO2 is lost
Solution Approach 1:
The measurement process is segmented into multiple distinct measurement conditions. The sensor performs separate measurements under different oxygen concentration conditions (first condition with higher oxygen, second condition with lower oxygen), allowing the total NOx to be measured while preserving the ability to calculate individual NO and NO2 concentrations through mathematical processing of the segmented measurement results.
Solution Approach 2:
The sensor dynamically changes the oxygen concentration in the measurement chamber between two distinct states. By controlling the oxygen concentration to vary between the first condition (higher oxygen) and second condition (lower oxygen), the sensor creates different measurement responses that enable differentiation of NO and NO2 components while maintaining accurate total NOx measurement.
2Measurement precision
If multiple measurement conditions are used to distinguish NO and NO2, then component differentiation is achieved, but measurement time increases
Solution Approach 1:
The sensor employs periodic switching between the first measurement condition (higher oxygen concentration) and second measurement condition (lower oxygen concentration). This periodic action allows multiple measurements to be performed in a cyclic manner, achieving component differentiation through the alternating measurement responses while maintaining a controlled and efficient measurement rhythm that minimizes total measurement time.
3Measurement precision
If oxygen concentration is controlled to differentiate NO and NO2, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The sensor introduces an intermediary mechanism (oxygen concentration adjustment chamber or reference electrode system) that mediates the measurement process. This intermediary allows indirect control of oxygen concentration conditions without requiring direct manipulation of the exhaust gas composition, thereby achieving accurate component differentiation while managing system complexity through a dedicated control intermediary rather than complex direct gas handling.
4Device complexity
If conventional sensors measure total NOx without component differentiation, then device complexity is reduced, but fault diagnosis capability is insufficient
Solution Approach 1:
The sensor exploits changes in measurement parameters (oxygen concentration) to achieve component differentiation. By varying the oxygen concentration parameter between two controlled conditions and processing the differential responses, the sensor maintains a relatively simple structure while gaining the ability to distinguish NO and NO2 concentrations, thereby improving fault diagnosis capability without proportionally increasing device complexity.
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 and prolonged measurement of NO, NO2, and NH3 concentrations, improving the accuracy of NOx purification systems and fault diagnosis in diesel engines, particularly in distinguishing between NO and NO2 in exhaust gases.
Implementation Method 1
a sensor element having a structural body made up from a solid electrolyte that exhibits at least oxygen ion conductivity
Implementation Method 2
utilizing multiple conditions and relational expressions to calculate the concentrations of NO, NO2, and NH3 by controlling oxygen concentration and temperature, allowing for precise measurement through electrochemical pump cells and sensor outputs
Data Source
AI summary
A gas sensor, and a method for measuring the concentrations of a plurality of target components in a gas to be measured are disclosed. The gas sensor is provided with: an oxygen concentration control means for controlling the oxygen concentration in an oxygen concentration adjustment chamber; a temperature control means for controlling the temperature of a sensor element; a condition setting means which sets the oxygen concentration of the oxygen concentration adjustment chamber and/or the temperature of the sensor element to conditions corresponding to the types of target components in the introduced gas to be measured; and a concentration calculation means which calculates the concentrations of the different target components on the basis of the respective sensor outputs obtained under the plurality of conditions corresponding to the types of target components.