Fluid Pressure Sensor With Coreless Inductive Coil
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Solution Overview
Problem
Existing pressure sensors for fluids require complex manufacturing processes and often include a magnetic core, making them difficult to produce and limiting their application, especially in medical imaging environments where magnetic interference is a concern.
Innovation Solution
A pressure sensor design where the coil's winding axis is parallel to the flexible pipe's central axis, eliminating the need for a magnetic core by varying the coil's self-inductance through deformation of the pipe's transverse surface, allowing for simpler production and expanded usage, including compatibility with MRI environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic core is used to vary the self-inductance of the coil, then the pressure measurement function is achieved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent removes the magnetic core from the sensor structure, extracting the problematic component that caused complexity. Instead of using a magnetic core to vary self-inductance, the invention uses the flexible pipe's own deformation to change the coil's transverse surface area and thus its self-inductance, achieving the same measurement function with simpler structure
Solution Approach 2:
The patent replaces the magnetic field-based measurement mechanism with a direct mechanical-electrical coupling mechanism. The flexible pipe's mechanical deformation directly changes the coil's geometric parameters (transverse surface), which in turn changes its electrical property (self-inductance), eliminating the need for magnetic cores and complex magnetic field interactions
2Measurement precision
If the coil is wound tightly around the flexible pipe, then the measurement sensitivity is improved, but the manufacturing complexity and risk of wire rupture increase
Solution Approach 1:
The patent applies different properties to different parts of the coil structure. The portion of the coil in contact with the flexible pipe has high sensitivity to pipe deformation, while other portions maintain a simpler structure that is easier to manufacture and less prone to rupture during the winding process
Solution Approach 2:
The patent uses a conductive wire with lower elasticity than the flexible pipe material, which is sufficient for the application. This partial elasticity provides enough flexibility for manufacturing and pipe deformation accommodation without requiring the wire to be as elastic as the pipe itself, thus reducing manufacturing complexity and rupture risk
3Reliability
If the winding axis of the coil is perpendicular to the central axis of the flexible pipe, then the self-inductance variation is achieved through magnetic core displacement, but the manufacturing process becomes more complex
Solution Approach 1:
The patent inverts the conventional approach by making the winding axis of the coil parallel to the central axis of the flexible pipe instead of perpendicular. This inversion changes the mechanism from magnetic core displacement to direct transverse surface area variation, simplifying the manufacturing process while maintaining reliable self-inductance variation for pressure measurement
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 simplifies the manufacturing process, reduces sensor size, and enhances measurement accuracy and reliability by using a conductive wire with less elastic material, ensuring precise pressure measurement without magnetic core complications.
Implementation Method 1
a flexible pipe extending around and along a central axis, this pipe being capable of containing the fluid whose pressure is to be measured and of deforming under the effect of the pressure exerted by the fluid
Implementation Method 2
a coil whose self-inductance varies according to the pressure of the fluid inside the flexible pipe
Data Source
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AI summary
This pressure sensor includes a coil whose self-inductance varies according to the pressure of a fluid inside the flexible hose, this coil having at least one turn (22) comprising: • a first and a second portion (40, 42) of its periphery mechanically connected, without degree of freedom, respectively, to a first and a second distinct location on the periphery of the hose so that the surface of this turn varies according to a deformation of the hose, and • a third (48) and a fourth (50) portions of its periphery located between the first and second portions and each on a respective side of the central axis of the hose, these third and fourth free portions each being separated from the flexible hose by a gap (52, 54).