Cap-Shed Filter Membrane for Pressure Sensor Icing Prevention
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Solution Overview
Problem
Differential pressure sensors face challenges in protecting their filter membranes from overload, particularly from water and dirt, which can lead to icing and blockage of reference air openings, affecting pressure equalization and sensor reliability.
Innovation Solution
A cap-shaped cover element is integrated with the housing cover to shield the filter membrane, ensuring it is protected from mechanical damage and water overload, while channels in the cap maintain air passage for pressure equalization, preventing liquid accumulation and icing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filter membrane is left exposed to protect against water and dirt, then the sensor reliability is improved, but the filter membrane is vulnerable to mechanical damage and overload
Solution Approach 1:
The housing cover is segmented into a main body and an integrated cap structure. The cap forms a separate protective chamber that shields the filter membrane while maintaining its filtering function. This segmentation allows the filter membrane to be protected from mechanical damage without compromising its exposure to atmospheric pressure for pressure equalization.
Solution Approach 2:
The cap is integrated into the housing cover, forming a nested structure where the cap contains the filter membrane within a protected chamber. This nesting provides mechanical protection while maintaining the functional exposure of the filter membrane to pressure differences.
2Strength
If the filter membrane is protected by a cap, then the filter membrane is shielded from mechanical damage, but air passage for pressure equalization may be blocked
Solution Approach 1:
The cap is designed with selective permeability - it is solid and protective in most areas, but includes specific localized openings that allow air passage. This local quality change enables the cap to provide mechanical protection while maintaining pressure equalization functionality through the strategically positioned openings.
3Productivity
If the filter membrane is exposed to the environment, then pressure equalization is achieved, but water and dirt can accumulate leading to icing and blockage
Solution Approach 1:
The cap acts as an intermediary structure between the external environment and the filter membrane. It provides a protected chamber that allows pressure equalization through the filter membrane while preventing direct accumulation of water and dirt on the membrane surface, thus avoiding icing and blockage.
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 protects the filter membrane from overload, ensures reliable pressure equalization, and prevents icing of the reference air opening, enhancing the sensor's operational reliability and accuracy.
Implementation Method 1
a gas-permeable filter membrane is built into a reference pressure port
Implementation Method 2
The pressure equalization element is generally designed to be water-repellent and impermeable to liquids
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a pressure compensation unit (10), particularly for a tank pressure sensor in a tank of a motor vehicle. The pressure compensation unit (10) comprises a housing cover (12, 50) and a gas-permeable filter membrane (26, 64) covering an air opening (24, 60). The pressure compensation unit (10) comprises a cap-shaped cover element (28, 60) covering the filter membrane (26, 64).