Gas Sensor Control Device for NOx Deterioration Detection
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Solution Overview
Problem
Existing NOx sensors face challenges in accurately detecting deterioration, particularly when the detection target gas, such as exhaust gas, has a high oxygen concentration, leading to significant variations in pump cell output current and reduced detection accuracy of the sensor cell's deteriorated state.
Innovation Solution
A gas sensor control device with a computer system that includes a voltage switching part, a pump cell output control part, and a deteriorated state detection part, which adjusts the pump cell output current variation range within a predetermined range before and after voltage switching, allowing for accurate detection of the sensor cell's deteriorated state by minimizing the impact of high oxygen concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump cell supply voltage is switched to detect sensor cell deterioration, then the detection capability is improved, but the pump cell output current varies significantly when oxygen concentration is high, reducing detection accuracy
Solution Approach 1:
The patent applies dynamics by making the pump cell supply voltage switchable between different levels (first and second voltage values) depending on the detection mode. The voltage can be dynamically adjusted: during normal operation a first voltage value is applied, and during deterioration detection a second voltage value is applied. This dynamic voltage switching allows the system to adapt to different operational requirements and resolve the contradiction between detection capability and measurement accuracy.
Solution Approach 2:
The patent changes the electrical parameter (supply voltage) of the pump cell to resolve the technical contradiction. By switching the pump cell supply voltage between different levels, the system can control the pump cell output current variation. When the second voltage value is applied during deterioration detection, it optimizes the detection conditions despite high oxygen concentration, thereby maintaining measurement precision while improving detection capability.
2Reliability
If the pump cell supply voltage is switched to detect sensor cell deterioration, then the detection capability is improved, but the sensor cell output current varies due to pump cell output variation, negatively influencing detection results
Solution Approach 1:
The patent implements feedback by monitoring the sensor cell output current in response to pump cell supply voltage switching. The system detects changes in sensor cell current that result from voltage switching, and uses this feedback information to determine sensor deterioration. This feedback mechanism enables automated deterioration detection without requiring complex external control processes.
Solution Approach 2:
The system performs self-service deterioration detection by automatically switching the pump cell supply voltage and monitoring the resulting sensor cell current variations. The gas sensor control device autonomously executes the detection process without requiring external intervention or complex additional control systems, thereby improving detection capability while avoiding excessive device complexity.
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 effectively suppresses the reduction in detection accuracy and enables correct detection of the sensor cell's deteriorated state, even in high oxygen concentration scenarios, by controlling the pump cell output current variation range, thereby improving the reliability of NOx sensor performance.
Implementation Method 1
The pump cell receives a pump cell supply voltage and adjusts a concentration of an oxygen gas component contained in a detection target gas introduced into the gas chamber on the basis of the received pump cell supply voltage
Implementation Method 2
The sensor cell detects a concentration of a specific gas component contained in the detection target gas after the pump cell has adjusted the concentration of the oxygen gas component contained in the detection target gas
Data Source
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AI summary
In a gas sensor, a pump cell adjusts a concentration of oxygen in a gas chamber based of a pump cell supply voltage. A sensor cell detects a concentration of a specific gas in a detection target gas after the pump cell has adjusted the concentration of oxygen. In a sensor control unit, a voltage switching part adjusts the pump cell supply voltage to be supplied to the pump cell. A pump cell output control part adjusts a variation range of a pump cell output current of the pump cell before and after a voltage switching process of the pump cell supply voltage to be within a predetermined variation range. A deteriorated state detection part detects a deteriorated state ratio of the sensor cell based on variation of an output current of the sensor cell due to the voltage switching process performed by the voltage switching part.