Humidity Sensor Malfunction Detection via Temperature-Relative Humidity Estimation
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Solution Overview
Problem
Existing humidity sensors for internal combustion engines fail to detect malfunctions and reduce accuracy due to continuous heating, which increases temperature and power consumption, affecting relative and absolute humidity detection.
Innovation Solution
A determination device that estimates and compares relative humidity at different temperatures to detect malfunctions in humidity sensors by analyzing the difference between estimated and actual relative humidity after heating or cooling the humidity-sensitive film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heater constantly heats the humidity-sensitive film to prevent dew condensation or fouling, then humidity detection accuracy is maintained, but the temperature of the humidity-sensitive film increases and detection accuracy of absolute humidity is reduced
Solution Approach 1:
The heater operates periodically rather than continuously. The control unit activates the heater only when the detected temperature is below a predetermined threshold, and deactivates it when the threshold is reached or exceeded. This periodic heating maintains the film temperature within an appropriate range while avoiding excessive temperature accumulation.
Solution Approach 2:
The system uses temperature detection feedback to control heater operation. The temperature detector continuously monitors the film temperature, and the control unit adjusts heater activation based on this feedback, creating a closed-loop control system that maintains temperature within acceptable limits.
2Reliability
If the heater constantly heats the humidity detector, then dew condensation or fouling of the humidity-sensitive film is restricted, but power consumption is increased
Solution Approach 1:
The heater operates periodically rather than continuously. The control unit activates the heater only when the detected temperature is below a predetermined threshold, and deactivates it when the threshold is reached or exceeded. This periodic heating maintains the film temperature within an appropriate range while avoiding excessive temperature accumulation.
Solution Approach 2:
The system uses the temperature detector and control unit to automatically monitor and regulate heater operation based on actual temperature conditions. This self-regulating mechanism ensures the heater operates only when necessary, minimizing power consumption while maintaining detection accuracy.
3Reliability
If the heater continues to heat the humidity detector, then the temperature of the temperature detector is increased and detection accuracy of temperature of intake air is reduced
Solution Approach 1:
The heater operates periodically rather than continuously. The control unit activates the heater only when the detected temperature is below a predetermined threshold, and deactivates it when the threshold is reached or exceeded. This periodic heating maintains the film temperature within an appropriate range while avoiding excessive temperature accumulation.
Solution Approach 2:
The system dynamically adjusts heater operation based on real-time temperature conditions. The control unit continuously monitors temperature detector readings and adjusts heater activation accordingly, creating a dynamic balance between preventing dew condensation and maintaining accurate temperature measurements.
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
Accurately detects malfunctions in humidity sensors, maintains detection accuracy, and reduces power consumption by only heating the film when necessary, ensuring precise humidity measurement.
Implementation Method 1
The heater heats the humidity-sensitive film. The temperature of the humidity-sensitive film is increased when the humidity-sensitive film is heated by the heater.
Implementation Method 2
The humidity detector has a humidity-sensitive film and detects a relative humidity of intake air based on a capacitance of the humidity-sensitive film.
Implementation Method 3
The temperature detector detects a temperature of the humidity-sensitive film.
Data Source
AI summary
A determination device determining malfunction of a humidity sensor includes a malfunction determination portion. The humidity sensor includes a humidity detector, a temperature detector and a heater. The humidity detector has a humidity-sensitive film in an intake passage and detects a relative humidity of intake air taken into an internal combustion engine for a vehicle. The temperature detector detects a temperature of the humidity-sensitive film. The heater heats the humidity-sensitive film and the temperature of the humidity-sensitive film is increased by the heater. The malfunction determination portion estimates an estimated relative humidity at a subsequent temperature from an original relative humidity and the subsequent temperature, and compares the estimated relative humidity at the subsequent temperature and an actual subsequent relative humidity to determine malfunction of the humidity detector.