Intake Air Humidity Sensor Thermal Isolation Design
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Solution Overview
Problem
Existing intake air flow rate measuring devices experience increased detection errors due to temperature increases of the humidity sensing element, which affects the accuracy of humidity measurement in engine compartments.
Innovation Solution
The device is designed with a suppressing portion that restricts heat transfer to the humidity sensing element by having a smaller cross-section than the base portion, using electric connectors with low thermal conductivity, and positioning the humidity sensing element away from direct heat sources, thereby maintaining the element's temperature close to the intake air temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the humidity sensing element is installed in the intake air duct within the engine compartment, then the device can measure the humidity of intake air, but the temperature of the humidity sensing element increases due to heat transfer from the engine compartment, causing detection error to increase
Solution Approach 1:
The patent introduces a heat insulating member as an intermediary substance between the humidity sensing element and the heat source (engine compartment or intake air duct). This heat insulating member acts as a thermal barrier that reduces heat transfer to the sensing element, thereby maintaining its temperature and ensuring accurate humidity detection without sacrificing measurement capability.
2Measurement precision
If the humidity sensing element is positioned close to the intake air duct for accurate measurement, then humidity can be detected, but heat from the duct transfers to the sensing element through the flange, deteriorating detection accuracy
Solution Approach 1:
The patent introduces a heat insulating member as an intermediary substance between the humidity sensing element and the heat source (engine compartment or intake air duct). This heat insulating member acts as a thermal barrier that reduces heat transfer to the sensing element, thereby maintaining its temperature and ensuring accurate humidity detection without sacrificing measurement capability.
Solution Approach 2:
The patent extracts the heat insulating function from the overall structure by adding a dedicated heat insulating member that is separate from the sensing element itself. This allows the sensing element to be positioned optimally for measurement while the insulating member independently handles the heat isolation function, preventing thermal interference.
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 reduces detection errors and maintains accurate humidity measurement by preventing heat-induced temperature increases in the humidity sensing element, ensuring precise humidity ratio detection.
Implementation Method 1
a heat insulating member to reduce heat transfer
Data Source
AI summary
The present disclosure provides an intake air flow rate measuring device. The intake air flow rate measuring device includes a flange, a casing, a flow rate sensor, a humidity sensing element, an element terminal, and a humidity terminal. The humidity terminal is spaced away from the element terminal. A portion of the casing between the element terminal and the humidity terminal is defined as a suppressing portion, and a cross-section of the suppressing portion is defined as a suppressing portion cross-section. An end portion of the casing close to the flange is defined as a base portion, and a cross-section of the base portion is defined as a base portion cross-section. The suppressing portion cross-section is set to be smaller than the base portion cross-section.