Bellows Isolated Pressure Sensor Capsule for Compact Downhole Transmitters
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Solution Overview
Problem
Conventional downhole pressure transmitters have fluid fill pathways that are robust due to the high pressure differential between wellbore fluids and atmospheric conditions, leading to larger diameters and less compact designs, whereas existing solutions fail to efficiently manage this pressure differential effectively.
Innovation Solution
A fluid pressure sensor capsule with a bellows isolator and a fluid fill pathway that extends from the process chamber to the interior chamber, allowing for the use of a less expensive isolation fluid by pressurizing the interior chamber with a bellows, which is sealed using a fill tube that can be crimped or welded, maintaining the seal under differential pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a robust fluid fill pathway is used to withstand high pressure differential, then reliability is improved, but device size increases and compactness is reduced
Solution Approach 1:
The fluid fill pathway is divided into multiple sections: a first portion in the process chamber and a second portion in the reference chamber, connected through a transition region. This segmentation allows each section to be optimized for its specific pressure environment, enabling the pathway to withstand high pressure differentials while maintaining a compact overall structure.
Solution Approach 2:
The fluid fill pathway transitions from a horizontal orientation in the process chamber to a vertical orientation in the reference chamber. This dimensional change allows the pathway to efficiently manage pressure differential forces by aligning the fluid column vertically where it can be contained more compactly, reducing the overall device diameter while maintaining reliability.
2Measurement precision
If expensive isolation fluid is used, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
A bellows isolator is introduced as an intermediary component between the process chamber and the reference chamber. The bellows maintains pressure equilibrium across the diaphragm while physically isolating the reference chamber, allowing the use of less expensive isolation fluid in the reference chamber while still achieving accurate pressure measurements through the isolated process chamber.
3Device complexity
If the fluid fill pathway is sealed before pressurization, then manufacturing complexity is reduced, but the ability to maintain seal under differential pressure is compromised
Solution Approach 1:
The fluid fill pathway is pre-filled with isolation fluid through fill ports before the bellows is expanded and sealed. This preliminary action ensures that the pathway is already filled and free of air bubbles, and the isolation fluid is in place to provide cushioning and pressure distribution before the final sealing occurs, simplifying the manufacturing process while ensuring seal integrity.
Solution Approach 2:
The isolation fluid is introduced into the fluid fill pathway beforehand to provide cushioning and pressure distribution. This pre-positioned fluid cushion helps distribute the differential pressure forces evenly across the seal interfaces, ensuring reliable sealing under high pressure differential conditions without requiring complex sealing mechanisms.
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 enables a more compact pressure transmitter design by managing the pressure differential efficiently, allowing the use of a less expensive isolation fluid and ensuring accurate pressure measurements without gas in solution, maintaining the isolation fluid in liquid form under varying temperature and pressure conditions.
Implementation Method 1
pressurizing the interior chamber with a bellows, which is sealed using a fill tube that can be crimped or welded, maintaining the seal under differential pressure
Implementation Method 2
maintaining the isolation fluid in liquid form under varying temperature and pressure conditions
Implementation Method 3
managing the pressure differential efficiently, allowing the use of a less expensive isolation fluid
Implementation Method 4
sealed using a fill tube that can be crimped or welded, maintaining the seal under differential pressure
Data Source
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AI summary
A pressure sensor capsule (102) includes a capsule body (122), an isolator (124), a pressure sensor (126), and a fluid fill pathway (140). The capsule body defines a process chamber (128). The isolator (124) is supported by the capsule body (122) and is exposed to the process chamber (128). The pressure sensor produces a sensor output that is indicative of a pressure within an interior chamber (130), which is isolated from the process chamber by the isolator (124). The fluid fill pathway extends from the process chamber to the interior chamber.