Gas Sensor Control Device for Rapid NOx Deterioration Diagnosis
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Solution Overview
Problem
Conventional NOx sensor deterioration diagnosis methods are inefficient, requiring time for transient response convergence and potentially causing electrode deterioration due to high pump cell voltage switching.
Innovation Solution
A control device for gas sensors that includes a pump cell, a sensor cell, an applied voltage switching unit, and a deterioration rate calculation unit, which calculates the deterioration rate based on the slope of transient changes in sensor cell output during voltage switching, allowing for quick and accurate diagnosis before steady-state stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the applied voltage to the pump cell is stepwisely varied and the change amount of the sensor cell output is detected after transient response convergence, then the deterioration diagnosis can be performed, but the diagnosis time is extended due to waiting for transient response stabilization
Solution Approach 1:
The patent applies preliminary action by calculating the deterioration rate during the transient change phase itself, rather than waiting for transient response stabilization. The slope calculation unit computes the deterioration rate based on the transient response characteristics that occur immediately when the pump cell voltage is switched, enabling diagnosis before the system reaches steady state.
2Productivity
If high pump cell voltage is applied to accelerate transient response, then the diagnosis speed is improved, but electrode deterioration may occur
Solution Approach 1:
The patent applies partial action by using a moderate voltage switching approach that is sufficient to generate observable transient response characteristics without exceeding the threshold that would cause electrode damage. The voltage is switched to a level that produces measurable transient effects while remaining within safe operational limits for the electrode.
3Stability of the object's composition
If the transient response convergence is waited for before diagnosis, then the measurement is stable, but the diagnosis cannot be performed quickly
Solution Approach 1:
The patent performs the deterioration rate calculation during the transient phase itself, treating the transient response characteristics as the measurement object rather than waiting for steady state. The slope calculation unit extracts meaningful diagnostic information from the transient response curve, eliminating the need to wait for stabilization.
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 rapid and accurate NOx sensor deterioration diagnosis without electrode damage, reducing diagnosis time and maintaining optimal sensor performance.
Implementation Method 1
a solid electrolyte body (244) having oxygen ion conduction
Implementation Method 2
the sensor electrode (252), and the common electrode (250), detects a concentration of nitrogen oxide
Data Source
AI summary
An SCU as a control device for the gas sensor (first and second NOx sensors) includes an applied voltage switching unit for switching an applied voltage of a pump cell when a deterioration detecting function is performed, and a deterioration rate calculation unit for calculating a deterioration rate of a sensor cell based on a slope during a transient change in an output of the sensor cell according to a switching of the applied voltage by the applied voltage switching unit.