Pressure Sensor Bellows Fluid Volume Thermal Error Reduction
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Solution Overview
Problem
Borehole pressure sensors face challenges in accurately measuring pressure due to extreme temperatures and pressures, which can affect the operation and longevity of equipment, and existing designs may be susceptible to errors from thermal effects and fluid volume changes.
Innovation Solution
A pressure sensor design featuring an outer body with a sensor cavity containing a resonator and a bellows, where the measuring fluid is located between the bellows and the outer body, allowing for reduced fluid volume and improved thermal resistance, with a measuring fluid area that is less susceptible to thermal effects, and a sealed volume that maintains accurate pressure readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bellows includes an internal volume where the measuring fluid is located, then the measuring fluid can be contained within the bellows, but the fluid volume is increased and thermal effects are amplified
Solution Approach 1:
The patent extracts the measuring fluid from the bellows internal volume and relocates it to the space between the bellows and the outer body. This extraction eliminates the harmful thermal effects that occurred when the fluid was contained within the bellows, while still allowing the fluid to serve its measurement function. The fluid is taken out of the problematic environment (bellows internal volume) and placed in a more favorable location.
2Measurement precision
If the measuring fluid is located within the bellows internal volume, then the bellows can expand and contract with the fluid, but thermal expansion errors increase
Solution Approach 1:
The patent introduces the space between the bellows and the outer body as an intermediary zone. This intermediate space allows the measuring fluid to be positioned away from the bellows internal volume, creating a buffer that isolates the fluid from direct thermal effects while still enabling it to respond to pressure changes. The intermediary space acts as a thermal barrier while maintaining mechanical coupling for measurement.
3Ease of operation
If the bellows flexes and expands in response to pressure changes, then the measuring fluid expands or contracts, but fluid volume changes cause measurement errors
Solution Approach 1:
The patent applies local quality by creating different functional zones: the bellows internal volume remains dedicated to bellows flexing and expansion, while the space between the bellows and outer body is dedicated to housing the measuring fluid. This spatial separation allows the bellows to perform its mechanical function without directly coupling its volume changes to the fluid, thereby eliminating measurement errors while preserving pressure response capability.
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 design enhances the accuracy and durability of pressure measurements by minimizing thermal errors and fluid volume-related inaccuracies, ensuring reliable operation in harsh borehole environments.
Implementation Method 1
One type of pressure includes a resonator such as a crystal (e.g. quartz) resonator. In such sensors, variations in pressure cause the resonant frequency of the resonator to change.
Implementation Method 2
During normal operation, the bellows flexes and expands or contracts in response to changes in the pressure of the measured fluid.
Implementation Method 3
The flexing and expanding of the bellows causes a measuring fluid contained within the bellows to, likewise, expand or contract.
Data Source
AI summary
A pressure sensor includes an outer body defining a sensor cavity and a resonator element located at least partially within the sensor cavity. The pressure sensor also includes a bellows having an outer side and an inner side and that is located at least partially within the outer body. the inner side of the bellows defines an internal volume and is configured to receive a measured fluid into the internal volume. The pressure sensor also includes a measuring fluid filling at least a portion of an area between the outer side and the outer body.