Humidity Sensor Water Droplet Adhesion Detection
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Solution Overview
Problem
Humidity sensors in internal-combustion engines face challenges in accurately determining valid humidity measurements due to water droplet adhesion, which causes incorrect readings of 100% humidity, leading to invalid detection values until the droplet is removed.
Innovation Solution
A humidity measuring device with a water droplet adhesion determination unit that analyzes changes in humidity and temperature to determine if a water droplet is adhering to the sensor element, using specific threshold conditions and coefficients to validate measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a humidity sensor is used to detect humidity, then humidity measurement is achieved, but water droplet adhesion causes incorrect readings of 100% humidity making it impossible to determine valid detection values
Solution Approach 1:
The patent introduces temperature as an intermediary parameter to mediate between the humidity sensor output and the determination of valid detection values. By analyzing the relationship between temperature changes and humidity readings, the system can distinguish whether 100% humidity readings are due to actual high humidity conditions or water droplet adhesion, thus resolving the reliability issue without compromising measurement precision
Solution Approach 2:
The patent implements a feedback mechanism where the humidity sensor output is continuously monitored and fed back to a determination unit that evaluates the validity of detection values based on temperature-humidity relationships. This feedback loop enables real-time identification of invalid readings caused by water droplet adhesion, allowing the system to maintain high measurement precision while ensuring detection value reliability
2Reliability
If water droplet adhesion is detected by monitoring electrostatic capacitance variation, then dew condensation detection is achieved, but it is impossible to determine whether the value is given due to water droplet adhesion or actual high humidity state
Solution Approach 1:
The patent transitions from single-dimensional electrostatic capacitance monitoring to two-dimensional analysis by incorporating temperature data alongside humidity readings. This dimensional expansion allows the system to distinguish between dew condensation and actual high humidity states, preserving complete humidity state information while maintaining reliable dew condensation detection
Solution Approach 2:
Temperature serves as an intermediary parameter that provides additional context to interpret electrostatic capacitance variations. By analyzing the correlation between temperature changes and humidity readings, the system can determine whether capacitance variations are caused by water droplet adhesion or actual humidity changes, preventing loss of humidity state information
3Reliability
If a water droplet covers the surface of a sensor element, then water droplet adhesion occurs, but gas humidity cannot be detected until the water droplet is removed
Solution Approach 1:
The patent performs preliminary analysis of temperature-humidity relationships before humidity detection becomes invalid. By continuously monitoring the correlation between temperature changes and humidity readings, the system can predict when water droplet adhesion is about to occur and take preventive measures or flag potential detection invalidity in advance, minimizing detection interruption time while maintaining reliability
Solution Approach 2:
The patent implements real-time feedback monitoring that continuously evaluates the validity of humidity detection based on temperature-humidity correlations. When water droplet adhesion is detected, the system immediately identifies the detection as invalid and can trigger alert mechanisms or switch to alternative measurement strategies, reducing the effective loss of detection time by enabling rapid response
Data Source
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Figure 3(a)~3(b)
AI summary
In order to provide a humidity measuring device capable of determining whether or not a detection value by a humidity sensor is valid, a humidity measuring device of the present invention is a humidity measuring device for measuring humidity of the intake air in an internal-combustion engine 2, and includes a water droplet adhesion determination means 51 for determining whether or not a water droplet adheres to a surface of a sensor element 22 of a humidity sensor 21, based on changes in the humidity and the temperature of the intake air. Thus, it is possible to determine whether or not a detection value by the humidity sensor 21 is valid.