Oil-Filled Pressure Sensor Membrane Channel Structures
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Solution Overview
Problem
Existing metallic pressure measuring cells face challenges in minimizing the volume of the membrane chamber while ensuring the membrane is easily deflectable in the axial direction and stiff in the radial direction, and in efficiently filling the chambers with a pressure transmitting medium due to the molding process which can seal the connecting channel.
Innovation Solution
A metallic pressure measuring cell with a surface structure on the membrane that overlaps the outer contour of the connecting channel inlet, allowing initial filling and deformation to ensure the membrane chamber is filled with pressure transmitting medium, and a surface contour on the base body that molds onto the membrane for optimal deformation and sealing prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the membrane is molded from the base body surface contour to minimize membrane chamber volume, then the membrane chamber volume is reduced, but the connecting channel outlet may be sealed by the membrane
Solution Approach 1:
The membrane is provided with a surface structure before attachment to the base body. This preliminary structure prevents the membrane from sealing the connecting channel outlet during the molding process, ensuring that the chambers can be filled with pressure transmitting medium while still achieving minimal membrane chamber volume through subsequent molding.
Solution Approach 2:
The surface structure is applied locally to specific regions of the membrane, particularly in areas that would otherwise seal the connecting channel outlet. This localized modification allows the membrane to maintain its molding capability for volume minimization while preventing sealing in critical areas where filling access is needed.
2Measurement precision
If the membrane is made thin and easily deflectable in axial direction, then pressure sensitivity is improved, but radial stiffness may be compromised
Solution Approach 1:
The membrane is given a pre-curvature or pre-deformation in the radial direction before attachment to the base body. This preliminary curvature provides radial stiffness to prevent excessive radial deformation, while the membrane remains thin and easily deflectable in the axial direction for pressure sensitivity. The pre-curvature acts as a structural reinforcement without adding significant thickness.
3Reliability
If the membrane chamber volume is minimized to reduce temperature influences, then temperature effects are reduced, but the connecting channel may become sealed during molding
Solution Approach 1:
The surface structure is applied to the membrane before attachment and molding operations. This preliminary action ensures that the connecting channel outlet remains open during the molding process that minimizes membrane chamber volume, allowing subsequent filling with pressure transmitting medium while achieving temperature stability through minimal chamber volume.
Solution Approach 2:
The surface structure acts as an intermediary element between the membrane and the connecting channel outlet. It prevents direct sealing contact between the membrane and channel outlet during molding, while still allowing the membrane to be molded to the base body surface for volume minimization. This intermediary structure enables both temperature stability and manufacturability.
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 ensures effective filling of the membrane chamber and maintains the required mechanical properties of the membrane, minimizing volume and ensuring accurate pressure measurement by preventing channel sealing during the molding process.
Implementation Method 1
a pressure sensor (7) arranged in a sensor chamber (71), wherein a connecting channel (9) is formed between the membrane chamber (51) and the sensor chamber (71) and the chambers are filled with a pressure transmitting medium (13) for transmitting a pressure acting on the membrane (5)
Implementation Method 2
The actual pressure sensor is usually made of a silicon chip. This chip consists of a membrane structured with piezoresistive resistors that bulges under pressure. The piezo chip is very sensitive to external influences
Implementation Method 3
the metallic membrane is easily deflectable in the axial direction, but comparatively stiff in the radial direction
Data Source
AI summary
A metallic pressure measuring cell having a base body, a metallic membrane situated and a pressure sensor situated in a sensor chamber of the base body, wherein the pressure on the membrane is transmitted to the pressure sensor by a connecting channel formed between a membrane chamber and a sensor chamber, wherein the chambers and connecting channel are filled with a pressure transmitting medium.