Air Flow Measuring Device Humidity Sensor Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional air flow measuring devices with humidity sensors in bypass passages suffer from reduced precision due to insufficient thermal insulation and increased wall surface resistance, leading to low responsivity and accuracy in measuring intake air humidity and flow rates.
Innovation Solution
The air flow measuring device includes a housing with a bypass flow passage for the flow sensor and a humidity sensor projecting into the intake passage, improving thermal insulation and reducing wall surface resistance by positioning the humidity sensor in the high-speed region of the intake passage, and integrating it with the housing during resin formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the humidity sensor is disposed in the bypass passage, then the flow rate can be measured, but the thermal insulation is insufficient and the precision is reduced
Solution Approach 1:
The humidity sensor is positioned to protrude from the bypass passage into the main intake passage, transitioning from a two-dimensional planar arrangement to a three-dimensional spatial configuration. This allows the sensor to access the high-speed airflow region in the main passage while maintaining its housing in the bypass passage, thereby improving thermal insulation and measurement precision simultaneously
2Productivity
If the humidity sensor is disposed in the bypass passage, then the structure is simplified, but the wall surface resistance increases and responsivity decreases
Solution Approach 1:
By extending the humidity sensor into the main intake passage from the bypass passage, the sensor is positioned in the high-speed airflow region. This spatial reconfiguration increases the relative velocity between the air and sensor surface, reducing wall surface resistance and enhancing responsivity while maintaining structural simplicity
3Measurement precision
If the humidity sensor is disposed in the bypass passage, then the manufacturing is easier, but the accuracy is reduced due to heat exchange with resin material
Solution Approach 1:
The humidity sensor is designed to protrude from the bypass passage into the main intake passage, creating a spatial separation between the sensor's sensing element and the resin material of the bypass passage. This dimensional arrangement reduces heat exchange with the resin material, improving measurement accuracy while maintaining ease of manufacture through integrated housing design
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 configuration enhances the accuracy and responsivity of humidity measurements while reducing the risk of sensor damage and simplifying component attachment, with the potential for integrating additional sensors like temperature and pressure sensors.
Implementation Method 1
a flow sensor that produces the signal in accordance with the intake air amount as a result of heat transfer between the sensor and the intake air taken into the bypass flow passage
Implementation Method 2
a humidity sensor that produces a signal in accordance with humidity of intake air flowing through the intake passage
Data Source
AI summary
An air flow measuring device includes a housing, flow sensor, and a humidity sensor. The housing defines a bypass flow passage through which intake it passes. A part of intake air is taken into the bypass flow passage to pass through the bypass flow passage. The flow sensor includes a sensing part disposed in the bypass flow passage, and produces a signal which is in accordance with the flow rate of intake air as a result of heat transfer between intake air taken into the bypass flow passage and the sensing part. The humidity sensor includes a sensing part exposed to the intake passage, and projects from an outer wall of the housing into the intake passage. The humidity sensor produces a signal which is in accordance with humidity of intake ail flowing through the intake passage.