Relative-Pressure Sensor Helical Groove Bushing
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Solution Overview
Problem
Relative-pressure sensors face challenges in ensuring that only dry ambient air reaches the measuring element and evaluation unit, particularly in environments with temperature fluctuations, where humidity can condense and interfere with pressure measurements.
Innovation Solution
A relative-pressure sensor design featuring a cylindrical bushing with a helical capillary-type groove that guides ambient air exclusively through the reference-pressure supply, eliminating the need for additional sealing elements and ensuring that humidity is absorbed by a drying chamber before reaching the measuring element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional sealing elements and filter elements are added to prevent humidity from entering the sensor, then the reliability of pressure measurements is improved, but the device complexity increases
Solution Approach 1:
The sealing function and the reference pressure supply function are merged into a single integrated reference pressure supply component. This component simultaneously provides the reference pressure to the measuring element and seals the reference pressure chamber, eliminating the need for separate sealing elements while maintaining measurement reliability
Solution Approach 2:
The reference pressure supply is designed to perform multiple functions: it supplies reference pressure to the measuring element, seals the reference pressure chamber, and prevents humidity ingress. This multi-functional design reduces the total number of components needed while maintaining measurement accuracy
2Adaptability or versatility
If the reference pressure supply is opened to the environment for providing atmospheric pressure, then the functionality of the sensor is improved, but humidity can enter and condense on cold parts, worsening measurement reliability
Solution Approach 1:
The reference pressure supply features a localized hydrophobic coating on its outer surface that repels water and humidity while allowing the reference pressure to be supplied. This local modification of surface properties enables the component to interact differently with water vapor versus gas molecules, maintaining atmospheric pressure reference functionality while preventing humidity ingress
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 design effectively prevents humidity from entering the sensor, maintaining accurate pressure measurements even under temperature changes, without requiring additional sealing components or filter elements, thus enhancing the reliability and efficiency of the sensor.
Implementation Method 1
at least one drying chamber arranged in the housing for taking up atmospheric humidity from the ambient air supplied through the reference-pressure supply
Implementation Method 2
In a capacitive relative-pressure sensor, a membrane is provided with a first electrode, and the side, opposite the membrane, of a measuring chamber is provided with a second and in some cases with a third electrode. The second electrode together with the first electrode forms a measuring capacitor, which is particularly sensitive to bending of the membrane
Implementation Method 3
Piezo-resistive relative sensors have a sensitive layer, whose electrical properties depend upon the applied pressure
Data Source
AI summary
A relative-pressure sensor for determining a pressure of a medium in relation to an atmospheric pressure includes a housing; a measuring element arranged in the housing, wherein the pressure to be measured acts upon an outer surface of the measuring element in contact with the medium; a reference-pressure supply, which supplies an inner surface of the measuring element with atmospheric pressure in the form of ambient air, an evaluation unit, which determines the pressure of the medium from a variable determined using the measuring element; and at least one drying chamber arranged in the housing for taking up atmospheric humidity from the ambient air supplied through the reference-pressure supply. A bushing can be pressed into the housing and has a capillary-type groove, which is helical at least in sections and runs around the bushing.