Sensor Housing Segmentation for Moisture Protection
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Solution Overview
Problem
Existing hot-film air-mass meters in motor vehicles are prone to water ingress and mechanical damage due to the vulnerability of their humidity sensors, which can lead to icing and electronic component damage, despite the use of separate humidity sensors and plastic frames for protection.
Innovation Solution
A sensor device with a sealed sensor housing that encloses both the flow sensor and humidity sensor, featuring a moisture-permeable membrane and a hardened gel to protect the electronics from fluid penetration, ensuring the humidity sensor can access the fluid medium without exposing the electronics to moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the humidity sensor is mounted on a separate circuit board with a plastic frame and integrated membrane, then the humidity sensor is protected from media and mechanical impact, but water ingress can still damage the electronic components through the inlet opening or drain hole
Solution Approach 1:
The sensor device is divided into distinct functional compartments: an electronics compartment housing the electronic components and a measuring compartment for the humidity sensor. The electronics compartment is sealed with a waterproof membrane, while the measuring compartment remains accessible to the fluid medium. This segmentation allows the humidity sensor to access moisture for measurement while protecting the electronics from water ingress.
Solution Approach 2:
A waterproof membrane acts as an intermediary barrier between the electronics compartment and the fluid medium. This membrane allows thermal energy to pass through for temperature measurement while blocking water molecules from reaching the electronic components. The membrane enables selective permeability, allowing necessary energy transfer while preventing harmful fluid ingress.
2Object-affected harmful factors
If the electronics compartment is completely sealed to protect from water ingress, then electronic components are protected, but the humidity sensor cannot access the fluid medium for measurement
Solution Approach 1:
The device is segmented into a sealed electronics compartment and an accessible measuring compartment. The humidity sensor is positioned in the measuring compartment where it can directly contact the fluid medium through a permeable membrane, while the electronics remain protected in the sealed compartment. This spatial segmentation resolves the contradiction between sealing and sensor access.
Solution Approach 2:
A thin waterproof membrane forms the boundary between the sealed electronics compartment and the fluid medium. This membrane is permeable to water vapor and thermal energy, allowing the humidity sensor to detect moisture and temperature while the membrane itself blocks liquid water from reaching the electronics. The flexible film enables selective interaction with the fluid medium.
3Reliability
If inlet openings and drain holes are provided for sensor access, then the humidity sensor can measure the fluid medium, but these openings create pathways for water ingress to damage electronics
Solution Approach 1:
The device separates the functions of measurement access and electronics protection by creating distinct compartments. The measuring compartment has openings for sensor access, while the electronics compartment remains sealed. This segmentation eliminates the need for openings in the electronics compartment, preventing water damage while maintaining measurement capability.
Solution Approach 2:
The waterproof membrane serves as an intermediary that allows the humidity sensor to access the fluid medium through selective permeability. It permits water vapor and thermal energy transmission for measurement while blocking liquid water ingress to the electronics, effectively mediating between the conflicting requirements of access and protection.
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
The solution effectively prevents water ingress and mechanical damage, enhancing the reliability and longevity of the sensor device by maintaining a dry environment for the electronics while allowing accurate humidity measurement.
Implementation Method 1
The humidity sensor features a humidity frame and a moisture-semi-permeable membrane at the same level as the electronics compartment cover
Implementation Method 2
The sensor housing has at least one inlet opening for supplying the humidity sensor with moisture from the fluid medium. The electronics compartment is sealed off from this inlet opening.
Data Source
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AI summary
The invention relates to a device (10) for detecting at least one flow property of a fluid medium. The sensor device (10) comprises at least one sensor housing (14). Accommodated in the sensor housing (14) is at least one electronics module (30) having at least one flow sensor (40) for detecting the flow property. The electronics module (30) is at least partly accommodated in an electronics chamber (20). In addition, at least one moisture sensor (42) is accommodated within the sensor housing (14). The sensor housing (14) has at least one inlet opening (46) for applying moisture from the fluid medium to the moisture sensor (42). The electronics chamber (20) is sealed off with respect to the inlet opening (46).