Gas Sensor Control Apparatus for Deterioration Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas sensor elements, particularly NOx sensors, experience delayed response due to deterioration, which affects their ability to accurately detect nitrogen oxides in vehicle exhaust, failing to meet stringent emission regulations.
Innovation Solution
A gas sensor control apparatus that includes a first and second measuring chamber, a solid electrolyte pump cell, and electrodes, with a voltage changing unit that alters the second chamber pump voltage to generate a transient response in the concentration-dependent current, allowing the deterioration determination unit to assess the sensor's state based on the current's peak value and decline pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gas sensor element is used for detecting nitrogen oxides in exhaust gas, then the detecting performance is required to be highly accurate, but the response is delayed as the sensor deteriorates with use
Solution Approach 1:
The system performs preliminary action by applying a determination voltage higher than the detection voltage before actual measurement to activate the sensor element and warm up the solid electrolyte. This preliminary voltage application reduces the response delay by ensuring the sensor is fully activated and at optimal temperature before the actual nitrogen oxide detection begins, thereby maintaining high detecting performance even after sensor deterioration
Solution Approach 2:
The system dynamically adjusts the voltage applied to the gas sensor element by switching between a determination voltage (higher than detection voltage) and a detection voltage. This dynamic voltage adjustment optimizes the sensor's response characteristics - the higher determination voltage accelerates the response by enhancing ion transport in the solid electrolyte, while the lower detection voltage maintains accurate measurement, thus resolving the contradiction between response speed and measurement precision
2Speed
If the second chamber pump voltage is increased to improve response speed, then the response delay is reduced, but the sensor deterioration is accelerated
Solution Approach 1:
The system implements periodic action by alternately applying determination voltage (higher than detection voltage) and detection voltage to the second chamber pump cell. The determination voltage is applied periodically to assess sensor state and reduce response delay, while the detection voltage is applied during normal operation. This periodic switching between voltage levels reduces response delay when needed without continuously exposing the sensor to high voltage that would accelerate deterioration, thus maintaining reliability
Solution Approach 2:
The system changes the voltage parameter dynamically - applying a determination voltage higher than the detection voltage only when sensor state assessment is needed or response acceleration is required. During normal nitrogen oxide detection, the lower detection voltage is maintained to prevent excessive stress on the sensor elements. This selective parameter change (voltage level adjustment) reduces response delay when necessary while minimizing sensor deterioration through controlled voltage management
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 accurate determination of the gas sensor element's deterioration state by analyzing the transient response of the concentration-dependent current, ensuring the sensor's performance meets regulatory standards.
Implementation Method 1
the second chamber pump cell applies a predetermined second chamber pump voltage between a second chamber electrode which faces an interior of the second measuring chamber and a reference electrode which is exposed to an atmosphere of a reference oxygen concentration, to thereby dissociate an oxygen-containing specific gas contained in the second measuring chamber
Implementation Method 2
a second chamber pump cell which is made of a solid electrolyte; and a pair of electrodes which are provided on the second chamber pump cell
Data Source
AI summary
A gas sensor control apparatus for controlling a gas sensor element, the gas sensor element including first and second measuring chambers and the gas sensor control apparatus including first chamber control unit for controlling an oxygen concentration in the first chamber; second chamber control unit for applying a second chamber pump voltage to disassociate an oxygen-containing specific gas contained in the second chamber and thereby generate a concentration-dependent current; current detecting unit; voltage changing unit for changing the second chamber pump voltage; and deterioration determination unit for determining the deterioration state of the gas sensor element based on a transient response of the concentration-dependent current.