Air-Fuel Ratio Sensor Temperature Compensation Without Heater
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Solution Overview
Problem
The existing air-fuel ratio sensors in internal combustion engines face challenges with precision detection due to temperature fluctuations of the sensor element, either when a heater is provided, increasing the sensor size, or when it is not provided, leading to fluctuating output currents and reduced precision.
Innovation Solution
An air-fuel ratio detection device that includes a sensor element, a voltage application circuit, a current detector, and a parameter detecting part to calculate the air-fuel ratio based on a temperature correlation parameter, such as the impedance of the sensor cell, allowing for correction of output currents to maintain precision despite temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a heater is provided at the air-fuel ratio sensor to maintain sensor element temperature, then detection precision is maintained, but the sensor size increases
Solution Approach 1:
The patent extracts the heater component from the air-fuel ratio sensor structure, eliminating the need for active heating while maintaining detection precision through alternative means (temperature compensation algorithms and adaptive calibration)
Solution Approach 2:
The patent changes the approach from maintaining constant temperature (thermal parameter control) to compensating for temperature variations through electrical parameter adjustments and computational correction, allowing the sensor to operate across a temperature range rather than at a fixed temperature
2Measurement precision
If a heater is provided at the air-fuel ratio sensor, then detection precision is maintained, but device complexity increases
Solution Approach 1:
The heater and its associated temperature control system are removed from the sensor structure, simplifying the device while compensation algorithms in the control unit handle temperature effects computationally
Solution Approach 2:
The patent replaces the mechanical/thermal control system (heater) with an electrical and computational system (adaptive calibration and temperature compensation algorithms in the ECU)
3Volume of moving object
If no heater is provided at the air-fuel ratio sensor, then sensor size is reduced, but detection precision deteriorates due to temperature fluctuations
Solution Approach 1:
The patent implements feedback mechanisms where the ECU continuously monitors output current variations and adjusts calibration values accordingly, compensating for temperature-induced drift without requiring active heating
Solution Approach 2:
The system performs preliminary calibration during warm-up periods and uses adaptive learning to pre-adjust calibration values based on anticipated temperature changes, preparing the detection system before temperature fluctuations affect precision
4Device complexity
If no heater is provided at the air-fuel ratio sensor, then device complexity is reduced, but detection precision deteriorates due to temperature fluctuations
Solution Approach 1:
The ECU uses feedback from output current measurements to continuously adjust calibration values, compensating for temperature effects through computational means rather than additional hardware
Solution Approach 2:
The system performs self-calibration and self-compensation for temperature effects using its own output current measurements and embedded algorithms, eliminating the need for external temperature control mechanisms
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 solution maintains the precision of air-fuel ratio detection even when the sensor element's temperature fluctuates, eliminating the need for a heater and reducing sensor size while ensuring accurate air-fuel ratio calculations.
Implementation Method 1
a sensor element (2) including a sensor cell (10)... an output current which flows through the sensor cell (10)... calculate an air-fuel ratio of the exhaust gas based on an output current
Implementation Method 2
the temperature correlation parameter is a temperature of the sensor element calculated from an impedance of the sensor cell
Data Source
AI summary
An air-fuel ratio detection device 1, 1′ comprises: a sensor element 2, 2′ including a sensor cell 10; a voltage application circuit 40, 40′ applying voltage to the sensor cell; a current detector 42, 42′ detecting an output current of the sensor cell; an air-fuel ratio calculating part 61 configured to calculate an air-fuel ratio of an exhaust gas; and a parameter detecting part 62 configured to detect or calculate a temperature correlation parameter correlated with a temperature of the sensor element. The air-fuel ratio calculating part is configured to calculate the air-fuel ratio of the exhaust gas based on the temperature correlation parameter and the output current detected when a predetermined voltage is applied to the sensor cell.