Capacitive Pressure Sensor Retaining Element Design
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Solution Overview
Problem
Pressure measuring devices face challenges in manufacturing costs due to the need for high-quality materials and effective sealing, especially in the food industry, where conventional stainless steel is insufficient, and existing solutions struggle with spring action and hygiene requirements for small diameter cells.
Innovation Solution
A pressure measuring device with a separate retaining element configured as a cap with a bent-over outer area, connected in a material-bonded or form-fit manner, allowing the base area to be freely movable and reducing material costs by using high-quality materials only for the retaining element, which comes into contact with the medium, while improving spring action and hygiene through a PTFE or PEEK gasket and concentric grooves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-quality materials (titanium, Hastelloy) are used for the process connector to meet food industry requirements, then chemical resistance and hygiene are improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent applies different material qualities to different parts of the device. The process connector uses conventional stainless steel (V4A) while only the retaining element that contacts the medium uses high-quality materials (titanium, Hastelloy). This localized application of high-quality material ensures chemical resistance where needed while minimizing overall manufacturing cost.
2Reliability
If a resilient sealing bar is used to compensate for pressure and temperature tolerances, then sealing reliability is improved, but the sealing bar cannot protrude far inwardly, limiting spring travel for small diameter cells
Solution Approach 1:
The patent resolves the space limitation by changing the geometric configuration. Instead of a straight sealing bar, the retaining element features a bent-over outer area portion that connects to the process connector at an angle. This angular configuration allows the sealing function to extend further into the available space without protruding beyond the glass solder ring, effectively increasing spring travel for small diameter cells.
3Ease of manufacture
If a separate retaining element is used to fix the pressure measuring cell, then assembly flexibility is improved, but the area in contact with the medium becomes difficult to clean, compromising hygiene requirements
Solution Approach 1:
The patent introduces a thin film sealing element (O-ring or flat gasket) made of PTFE or similar material that creates a smooth, continuous sealing surface. This thin film configuration eliminates dead spaces and crevices where contaminants could accumulate, making the device easy to clean and compliant with hygiene requirements while maintaining the benefits of a separate retaining element for assembly flexibility.
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 reduces manufacturing costs by using common stainless steel for the housing and process connector, enhances spring action for small diameter cells, and ensures improved hygiene and accuracy by minimizing dead space and gaps, meeting stringent industry requirements.
Implementation Method 1
the base area portion is freely movable in the axial direction and thus acquires a spring elastic property
Implementation Method 2
ensures improved hygiene and accuracy by minimizing dead space and gaps, meeting stringent industry requirements
Implementation Method 3
Exertion of pressure causes a deformation of the membrane, which results in a capacitance change of the measuring capacitor
Implementation Method 4
a piezoresistive or capacitive measuring cell
Data Source
AI summary
A pressure measuring device comprises a capacitive pressure measuring cell, a process connector including a retaining element, a housing mounted on the process connector, and a sealing element arranged between an inwardly projecting region of the retaining element and the pressure measuring cell. The retaining element is configured with a cap with a base area portion and an outer area portion bent over with respect thereto and fitted over an end face of the process connector. The retaining element is in a material-bonded and/or form-fit manner connected to the process connector exclusively in the bent-over outer area portion so that the base area portion assumes a resilient property.