Gas Sensor Control Device for Accurate NOx Diagnosis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional NOx sensor deterioration diagnosis methods are affected by unintended changes in oxygen or NOx concentrations in the exhaust gas, leading to inaccurate determination of sensor cell deterioration.
Innovation Solution
A gas sensor control device with a voltage switching unit that adjusts oxygen concentration in the gas chamber, an output change calculation unit, a concentration difference calculation unit, and a deterioration determination unit, which calculates and uses output change and concentration difference parameters to accurately determine sensor cell deterioration despite fluctuations in oxygen or NOx concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage switching method is used to diagnose sensor cell deterioration, then the diagnosis can be performed, but the determination accuracy is reduced due to unintended changes in oxygen or NOx concentrations
Solution Approach 1:
The control device calculates a concentration difference parameter that reflects the actual change in oxygen or NOx concentration during the voltage switching process. This feedback information is then used to correct the output change parameter, allowing the deterioration determination unit to accurately assess sensor cell deterioration while compensating for unintended concentration changes in the exhaust gas.
Solution Approach 2:
The invention introduces a concentration difference parameter as a new measurement dimension. By monitoring and calculating the actual concentration change of oxygen or NOx during voltage switching, the system transforms a single-parameter diagnosis approach into a multi-parameter approach, thereby resolving the contradiction between performing diagnosis and maintaining determination accuracy.
2Measurement precision
If voltage switching is performed to increase oxygen concentration for diagnosis, then sensor cell response can be evaluated, but unintended changes in exhaust gas concentration occur
Solution Approach 1:
Instead of trying to prevent the unintended concentration changes that occur during voltage switching, the invention converts this harmful effect into a useful diagnostic parameter. The concentration difference parameter is calculated to reflect these actual changes, and this information is used to correct the deterioration assessment, turning what was previously a source of error into a valuable feedback mechanism.
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
The solution enables proper determination of sensor cell deterioration even with fluctuations in oxygen or NOx concentrations, improving the accuracy of NOx sensor diagnosis and preventing exhaust system failures.
Implementation Method 1
a pump cell that adjusts an oxygen concentration in a detection target gas introduced into a gas chamber by application of a voltage
Implementation Method 2
a sensor cell that detects a concentration of a specific gas component from the detection target gas after the adjustment of the oxygen concentration by the pump cell
Data Source
AI summary
Each of SCUs to includes: a voltage switching unit that performs a first voltage switching to increase an oxygen concentration in a gas chamber and a second voltage switching to decrease the oxygen concentration in the gas chamber after the execution of the first voltage switching; an output change calculation unit that calculates an output change parameter indicating a change in output of the sensor cell according to the voltage switching; a concentration difference calculation unit that calculates a concentration difference parameter indicating a concentration difference in the oxygen concentration or in the concentration of the specific gas in the detection target gas between before the first voltage switching and after the second voltage switching; and a deterioration determination unit that determines a deterioration state of the sensor cell based on the output change parameter and the concentration difference parameter.