Oxygen Sensor Voltage Correction for Air-Fuel Ratio Feedback
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Solution Overview
Problem
Conventional engine control methods face challenges in accurately measuring air-fuel ratios outside the stoichiometric range due to temperature characteristics of oxygen sensors, leading to complications in feedback control, delayed convergence, and increased labor in retrofitting temperature sensors.
Innovation Solution
An engine control device and method that corrects oxygen sensor output voltage using operating state information, eliminating the need to estimate sensor temperature by calculating a correction coefficient based on engine and throttle data, allowing for precise air-fuel ratio feedback control without direct temperature estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If oxygen sensor output voltage is used to measure air-fuel ratio outside stoichiometric range, then air-fuel ratio feedback control can be extended to wider operating range, but measurement precision deteriorates due to temperature characteristics causing significant voltage variations
Solution Approach 1:
The patent changes the parameter used for correction from temperature-based to output voltage-based correction. By calculating a correction coefficient from the oxygen sensor's own output voltage characteristics, the system adapts to temperature variations without requiring temperature sensors, thus extending measurement range while maintaining precision across different operating conditions
Solution Approach 2:
The oxygen sensor serves itself by using its own output voltage characteristics to generate the correction coefficient. The ECU calculates the correction coefficient based on the relationship between output voltage and air-fuel ratio, allowing the sensor to self-correct for temperature effects without external temperature sensing, enabling versatile operation with maintained precision
2Measurement precision
If temperature sensors are added to detect oxygen sensor temperature for correction, then measurement precision improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the temperature correction function from the oxygen sensor itself by utilizing its output voltage characteristics. Instead of adding external temperature sensors, the system extracts correction information directly from the oxygen sensor's voltage output, eliminating the need for additional temperature sensing hardware while maintaining measurement precision
Solution Approach 2:
The oxygen sensor performs multiple functions: it not only detects air-fuel ratio but also provides information for temperature compensation. By calculating the correction coefficient from the sensor's own output characteristics, the system makes the oxygen sensor a multi-functional component that handles both measurement and self-correction, reducing overall system complexity
3Measurement precision
If map data based on measured air-fuel ratio and estimated temperature is used for correction, then measurement precision improves, but device complexity and development labor increase due to complicated correction coefficient determination
Solution Approach 1:
The patent changes the correction approach from using map data based on multiple parameters (measured air-fuel ratio and estimated temperature) to a simpler method using only the oxygen sensor output voltage. This parameter reduction simplifies the correction coefficient determination while maintaining precision by focusing on the most relevant voltage characteristics
Solution Approach 2:
The patent extracts only the essential correction information from the complex map data approach. Instead of using comprehensive map data requiring temperature estimation and multiple measurements, the system extracts correction coefficients directly from the oxygen sensor output voltage characteristics, simplifying the determination process while maintaining accuracy
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
This approach enables accurate air-fuel ratio feedback control, reduces computational complexity, and simplifies the development process by eliminating the need for temperature sensors, improving convergence and reducing labor costs.
Implementation Method 1
an oxygen sensor, the output voltage value of which changes in response to a concentration of oxygen in exhaust gas of the engine
Data Source
AI summary
Provided is an engine control device for correcting output characteristics of an oxygen sensor and performing air-fuel ratio feedback control. The engine control device includes various sensors for detecting operating state information of an engine, an oxygen sensor, and air-fuel ratio feedback controller to adjust an amount of fuel injected into the engine, on the basis of the operating state information and an output voltage value of the oxygen sensor, wherein the air-fuel ratio feedback controller calculates, in accordance with the operating state information based on detection results from the various sensors, a coefficient for correcting the output voltage value, implements air-fuel ratio feedback control on the basis of an air-fuel ratio feedback control correction amount calculated using a corrected oxygen sensor output voltage value calculated on the basis of the coefficient, and adjusts the amount of fuel injected into the engine.