Integrated Gas Sensor Cell for NOx Measurement Accuracy
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Solution Overview
Problem
The existing gas sensor devices for measuring gas components like NOx in internal combustion engine exhausts face accuracy issues due to differences in material between oxygen monitor cell and sensor cell electrodes, leading to reduced sensitivity and measurement errors.
Innovation Solution
A gas sensor device with a solid electrolyte body, a measurement gas space, a reference gas space, a pump cell, and a sensor cell, where the oxygen ion current value measured after fuel interruption is subtracted from the value measured during fuel spraying to correct for residual oxygen effects, eliminating the need for a separate oxygen monitor cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different materials are used for electrodes of oxygen monitor cell and sensor cell, then oxygen concentration regulation is achieved, but measurement accuracy deteriorates due to sensitivity differences and aging effects
Solution Approach 1:
The patent merges the oxygen monitor cell and sensor cell into a single integrated sensor cell structure. The sensor cell performs both oxygen concentration regulation and residual oxygen measurement functions using the same electrode materials (first electrode and second electrode on the solid electrolyte body), eliminating the sensitivity mismatch and aging differential that occurred between separate cells with different materials.
Solution Approach 2:
The sensor cell is designed to perform multiple functions: it regulates oxygen concentration through voltage application between the first and second electrodes, and simultaneously measures both the regulated oxygen concentration and the given gas component concentration. This multi-functional design eliminates the need for separate monitor and sensor cells with different specialized materials.
2Measurement precision
If oxygen monitor cell with different electrode material is used, then oxygen concentration measurement is enabled, but device complexity increases and measurement error occurs
Solution Approach 1:
The patent combines the previously separate oxygen monitor cell and sensor cell into a single integrated sensor cell. The first electrode and second electrode are both disposed on the solid electrolyte body, forming a unified structure that performs both monitoring and sensing functions, thereby reducing device complexity while maintaining measurement accuracy.
Solution Approach 2:
The integrated sensor cell performs multiple functions that were previously distributed across separate cells: oxygen concentration regulation through voltage application, oxygen concentration measurement through ion current detection, and given gas component concentration measurement. This universal design eliminates the need for separate monitor and sensor cells.
3Adaptability or versatility
If separate oxygen monitor cell and sensor cell are used, then oxygen regulation and measurement functions are achieved, but residual oxygen effects cause measurement errors
Solution Approach 1:
The patent merges the oxygen monitor cell and sensor cell into a single integrated sensor cell structure. Since both measurement functions are performed by the same cell with identical electrode materials and environmental conditions, the residual oxygen concentration is consistently accounted for in both measurements, allowing accurate determination of given gas component concentration through subtraction of the oxygen ion current values.
Solution Approach 2:
The sensor cell provides feedback on the actual oxygen concentration in the measurement gas by measuring the oxygen ion current. This feedback information is used to correct the given gas component concentration measurement by subtracting the oxygen contribution, thereby eliminating measurement errors caused by residual oxygen.
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 approach enhances measurement accuracy by reducing the impact of residual oxygen on NOx concentration determination, simplifying the device structure and eliminating material mismatch-related errors.
Implementation Method 1
a solid electrolyte body which has oxygen ion conductivity
Implementation Method 2
voltage is applied between the pump electrode and a reference electrode disposed on a surface of the solid electrolyte body which faces the reference gas space to regulate a concentration of oxygen in the measurement gas space
Implementation Method 3
the sensor cell working to measure an oxygen ion current flowing between the sensor electrode and the reference electrode
Implementation Method 4
a measurement gas space which is formed on one of surfaces of the solid electrolyte body and into which the exhaust gas is introduced as a measurement gas through a diffusion resistor
Data Source
AI summary
A gas sensor device is equipped with a pump cell and a sensor cell. The pump cell works to regulate the concentration of oxygen in a measurement gas space. The sensor cell works to measure an oxygen ion current flowing between a sensor electrode and a reference electrode. The gas sensor device is designed to subtract the oxygen ion current value I2, as measured by the sensor cell a given period of time after spraying of fuel into the internal combustion engine is interrupted, from the oxygen ion current value I1, as measured by the sensor cell when the fuel is being sprayed into the internal combustion engine, to derive the concentration of a given gas component based on the corrected oxygen ion current value I. This results in improved accuracy in determining the concentration of the given gas component.