Oxygen Ion Pump Cell Segmentation for Exhaust Gas Measurement
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Solution Overview
Problem
Existing methods for detecting bound oxygen in exhaust gases from internal combustion engines, such as nitrogen oxides NOx, sulfur oxides SOx, and carbon oxides COx, are inaccurate due to interference from molecular oxygen, leading to deviations in measurement accuracy and pinpointing of component malfunctions in on-board diagnostics (OBD) systems.
Innovation Solution
A device with at least a first pump cell, a reference cell, and a second pump cell is used to separate and measure oxygen ions, where the first pump current removes molecular oxygen ions and the second pump current decomposes bound oxygen, with a constant sum of currents maintained to improve measurement accuracy by excluding the influence of molecular oxygen ions in the reference gas space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If molecular oxygen is present in the measurement gas space during detection of bound oxygen, then the detection process can proceed, but measurement accuracy deteriorates due to interference from molecular oxygen ions
Solution Approach 1:
The device segments the oxygen ion detection process into two distinct pathways: one for molecular oxygen ions (removed by the first pump cell) and one for bound oxygen ions (transported by the second pump cell through the reference cell). This segmentation allows selective removal of interfering molecular oxygen while preserving the measurement of bound oxygen, thereby resolving the contradiction between maintaining detection capability and eliminating measurement interference.
Solution Approach 2:
The first pump cell extracts and removes molecular oxygen ions from the measurement gas space before they can interfere with the detection process. By taking out the harmful molecular oxygen component separately, the system enables accurate detection of bound oxygen without interference, directly addressing the measurement accuracy problem.
2Measurement precision
If a reference cell is used to transport oxygen ions, then the measurement process can be maintained, but measurement accuracy deteriorates when molecular oxygen ions are transported along with bound oxygen ions
Solution Approach 1:
The first pump cell performs a preliminary action by removing molecular oxygen ions from the measurement gas space before the oxygen ions reach the reference cell. This preliminary removal prevents contamination of the reference gas space with molecular oxygen ions, ensuring that only bound oxygen ions are transported through the reference cell to the second pump cell, thereby maintaining measurement accuracy.
Solution Approach 2:
The first pump cell acts as an intermediary between the measurement gas space and the reference cell, selectively removing molecular oxygen ions before they can contaminate the reference gas space. This intermediary function protects the reference cell from interference while allowing the measurement process to continue, resolving the contradiction between maintaining the reference cell function and preventing contamination.
3Measurement precision
If pump current is used to transport oxygen ions, then oxygen detection can be performed, but device complexity increases with multiple pump cells required to separate different oxygen sources
Solution Approach 1:
The device is segmented into three functionally distinct pump cells, each handling a specific aspect of the oxygen ion detection process: the first pump cell removes molecular oxygen ions, the reference cell transports oxygen ions under controlled conditions, and the second pump cell measures bound oxygen ions. This segmentation, while increasing structural complexity, enables precise separation and measurement of different oxygen sources, achieving high detection accuracy that justifies the added complexity.
Solution Approach 2:
Each pump cell is designed with multi-functionality: the first pump cell not only removes molecular oxygen but also protects the reference cell; the reference cell serves as both a transport pathway and a controlled environment chamber; the second pump cell both transports and measures bound oxygen ions. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while achieving precise measurement.
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 the accuracy of detecting bound oxygen in exhaust gases, reducing errors and improving the dynamic behavior and diagnostic capabilities of OBD systems by isolating the oxygen ion flow from molecular oxygen, thereby improving the precision of gas component proportion measurement.
Implementation Method 1
a first pump cell (112) which is in contact with a measurement gas space (126), the first pump cell (112) serving to transport oxygen ions out of the measurement gas space (126)
Implementation Method 2
the measurement gas component with the bound oxygen is decomposed by means of catalysis in such a way that further oxygen ions are generated from the oxygen previously bound
Implementation Method 3
a second pump cell (140) which is in contact with a reference gas space (136), with a second pump current (146) serving to transport oxygen ions from the measurement gas space (126) through the reference gas space (136)
Data Source
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AI summary
A method and a device are described for detecting at least a portion of a measuring gas component containing bound oxygen in a gas mixture, in particular in an exhaust gas of an internal combustion engine, in a measuring gas chamber by detecting a portion of oxygen that is generated by a reduction of the measuring gas component containing the bound oxygen, in the presence of molecular oxygen, in the device, which includes at least one first pump cell, one reference cell, and one second pump cell. The method includes the following steps: a) generating a first pump current in the first pump cell in such a way that transport of a first portion of oxygen ions takes place between the measuring gas chamber and the surroundings of the device; b) applying a reference pump current to the reference cell in such a way that a second portion of the oxygen ions is transported into a reference gas chamber; c) decomposing the measuring gas component containing the bound oxygen by catalysis at an electrode of the second pump cell, as the result of which additional molecular oxygen is generated from the measuring gas component; d) applying a second pump current to the second pump cell in such a way that a portion of further oxygen ions that are formed from the additional molecular oxygen is transported into the reference gas chamber; and e) holding a sum of currents, formed from the reference pump current and from the second pump current, constant.