Gas Sensor Oxygen Pump Current Correction for Crack Errors
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Solution Overview
Problem
Gas sensors face challenges in accurately measuring oxygen, NOx, and NH3 concentrations in exhaust gases from gasoline vehicles, particularly in determining the air-fuel ratio around the stoichiometric range due to potential cracks in the sensor element, leading to inaccurate oxygen concentration readings.
Innovation Solution
A gas sensor with a determining and correcting part that adjusts the oxygen pump current based on detected oxygen concentration discrepancies, using an oxygen pump cell and reference gas chamber to correct for errors and accurately measure air-fuel ratios, enabling precise detection of NOx and NH3 concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gas sensor is used to detect oxygen concentration in exhaust gas, then the air-fuel ratio can be measured, but cracks in the sensor element cause inaccurate detection
Solution Approach 1:
The patent applies preliminary action by detecting cracks in the sensor element before they cause significant measurement errors. The control unit continuously monitors sensor element characteristics and identifies crack formation early, enabling preventive correction of measurement data before accuracy deteriorates beyond acceptable limits
Solution Approach 2:
The patent implements feedback by using the detected oxygen concentration to control the oxygen pump cell, which actively regulates oxygen partial pressure in the measurement chamber. This closed-loop feedback system compensates for measurement deviations caused by cracks, maintaining accurate air-fuel ratio detection despite sensor element degradation
2Adaptability or versatility
If the oxygen pump cell is controlled based on detected oxygen concentration, then air-fuel ratio measurement is enabled, but crack-induced detection errors propagate to NOx and NH3 measurements
Solution Approach 1:
The patent uses an intermediary approach by introducing a control unit that acts as a mediator between the cracked sensor element and the measurement system. The control unit detects crack-induced errors and applies correction algorithms to oxygen concentration readings before using them to control the oxygen pump cell, preventing error propagation to NOx and NH3 measurements
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the oxygen pump cell control parameters based on real-time oxygen concentration detection. When cracks are detected, the control unit modifies pump cell operating parameters to compensate for measurement errors, maintaining accurate multi-gas detection despite sensor degradation
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 allows for high-accuracy long-term measurement of oxygen, NOx, and NH3 concentrations by correcting for sensor element errors, ensuring accurate air-fuel ratio judgment and improved exhaust gas cleaning system control.
Implementation Method 1
a sensor element comprising: a base part in an elongated plate shape, including an oxygen-ion-conductive solid electrolyte layer
Implementation Method 2
an oxygen pump cell including: an intracavity oxygen pump electrode disposed in the measurement-object gas flow cavity; and an extracavity oxygen pump electrode disposed at a position different from the measurement-object gas flow cavity on the base part and corresponding to the intracavity oxygen pump electrode
Implementation Method 3
a concentration detecting part for detecting an oxygen concentration in a measurement-object gas based on a current value of an oxygen pump current flowing through the oxygen pump cell
Data Source
AI summary
A gas sensor includes a sensor element and a control unit for controlling the sensor element. The sensor element includes: a base part; a measurement-object gas flow cavity; an oxygen pump cell including an intracavity oxygen pump electrode and an extracavity oxygen pump electrode; a reference gas chamber; and a reference electrode disposed in the reference gas chamber. The control unit includes: a concentration detecting part for detecting an oxygen concentration in a measurement-object gas based on a current value of an oxygen pump current flowing through the oxygen pump cell; and a determining and correcting part for performing correction to the current value of the oxygen pump current flowing through the oxygen pump cell when determining that an oxygen concentration detected by the concentration detecting part is different from an actual oxygen concentration in the measurement-object gas.