Gas Concentration Detection Device Resolving Sensor Deterioration
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Solution Overview
Problem
Existing NOx sensors in internal combustion engine exhaust systems face detection accuracy issues due to poisoning substances like manganese and silicon, leading to deterioration and reduced sensitivity, which requires significant fluctuation of NOx concentration for deterioration determination.
Innovation Solution
A gas concentration detection device with a pump cell, sensor cell, and monitor cell, along with a voltage adjustment unit and sensitivity determination unit, that adjusts pump cell voltage to increase residual oxygen concentration, allowing for sensitivity determination without significant NOx concentration fluctuation, thereby detecting cell deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the range of NOx concentration fluctuation is widened to grasp the fluctuation of output value from the NOx sensor, then the deterioration determination becomes more accurate, but exhaust emission deterioration becomes inevitable
Solution Approach 1:
The invention changes the parameter being measured from NOx concentration to residual oxygen concentration. By measuring how much oxygen remains after the pump cell removes oxygen, the system can determine sensor deterioration without requiring wide fluctuations in exhaust gas composition. This parameter substitution resolves the contradiction by enabling accurate deterioration detection without causing emission deterioration.
Solution Approach 2:
The invention introduces residual oxygen concentration as an intermediary measurement parameter. Instead of directly measuring NOx concentration fluctuations, the system uses the pump cell to remove oxygen and then measures the remaining oxygen level. This intermediary approach allows deterioration determination without requiring the harmful wide fluctuations of exhaust emission components.
2Measurement precision
If a pump cell voltage is applied to discharge oxygen from the measurement chamber, then the residual oxygen concentration increases for better sensitivity determination, but the detection current decreases due to cell deterioration
Solution Approach 1:
The system applies pump cell voltage and monitors the resulting detection current as feedback. By observing how the detection current responds to the applied voltage and the resulting residual oxygen concentration changes, the system can determine gas sensitivity. The feedback mechanism allows the system to account for cell deterioration effects while still achieving accurate sensitivity determination.
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 determination of gas sensitivity decline without significant NOx concentration fluctuation, maintaining detection accuracy and reducing exhaust emission deterioration.
Implementation Method 1
the first pump electrode causes a decomposition reaction by means of inter-electrode voltage application and discharges oxygen out of the first chamber
Implementation Method 2
the pump electrode for NOx detection reacts to NOx gas in gas by means of inter-electrode voltage application and outputs a NOx concentration in the form of a current signal
Implementation Method 3
a monitor cell (249) detecting a concentration of a residual oxygen in the exhaust gas from which the oxygen is discharged
Data Source
AI summary
A gas concentration detection device includes a pump cell, a sensor cell, a monitor cell, a sensor current detection unit detecting a current outputted by the sensor cell, a monitor current detection unit detecting a current outputted by the monitor cell, a voltage adjustment unit adjusting a pump cell voltage applied to the pump cell, and a sensitivity determination unit determining a gas sensitivity of at least one of the sensor cell or the monitor cell. The voltage adjustment unit changes the pump cell voltage from a target voltage into a detection voltage where the concentration of the residual oxygen supplied to the sensor cell and the monitor cell is increased. The sensitivity determination unit determines the gas sensitivity based on a detection current detected by at least one of the sensor current detection unit or the monitor current detection unit in accordance with the concentration of the residual oxygen.