Pressure Sensor Diaphragm Isolation via Vacuum Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pressure sensors in aerospace and commercial systems face challenges in isolating process fluids from electronic sensing elements, leading to potential chemical destruction, conductive issues, and non-correctable errors due to the limitations of traditional oil-filled barriers, which can fail if the oil leaks.
Innovation Solution
A pressure-sensing apparatus with a sealed chamber and a flexible diaphragm, where the diaphragm is in fluid communication with two separate circuits, allowing differential pressure sensing without exposing the sensor elements to the process fluid, and utilizing a silicon-on-insulator (SOI) substrate with strain-gauge and piezoelectric resistance-bridge sensing elements for accurate pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin corrugated metal barrier with inert oil fill is used to isolate the process fluid from the sensor, then the sensor is protected from chemical destruction and current leakage, but non-correctable errors increase as the isolator diameter decreases and the system fails if the oil leaks
Solution Approach 1:
The patent removes the inert oil fill from the isolation chamber, replacing it with a vacuum or inert gas environment. This extraction eliminates the oil-related failure modes (leakage, outgassing, temperature limitations) while maintaining the isolation function through the corrugated metal barrier alone, thereby improving measurement accuracy without sacrificing sensor protection.
Solution Approach 2:
The patent changes the physical state of the isolation medium from liquid (inert oil) to gas or vacuum. This parameter change eliminates the harmful effects associated with liquid oil (leakage, outgassing, temperature-dependent gelling) while maintaining the protective isolation function, resolving the contradiction between reliability and measurement precision.
2Volume of moving object
If the diameter of the isolator is decreased, then the device size is reduced, but non-correctable errors increase to the third power of the diameter ratio
Solution Approach 1:
By removing the inert oil fill, the patent eliminates the source of non-correctable errors that scale with the third power of diameter reduction. The isolation chamber can now be miniized without the oil-induced measurement degradation, allowing small isolator diameter while maintaining measurement accuracy.
3Reliability
If inert oil is used to fill the isolation chamber, then the sensor is isolated from the process fluid, but the oil presents additional failure mechanisms including leakage and temperature limitations
Solution Approach 1:
The patent extracts the inert oil from the isolation chamber, replacing it with vacuum or inert gas. This eliminates temperature-dependent failures (gelling at cold temperatures, degradation at high temperatures) while maintaining effective isolation through the corrugated metal barrier, thereby expanding the operational temperature range.
Solution Approach 2:
The patent uses vacuum or inert gas instead of inert oil to create an inert environment that prevents chemical reactions and eliminates temperature-dependent failures. This inert atmosphere maintains isolation effectiveness across a wide temperature range without the failure mechanisms associated with liquid oil.
4Reliability
If a corrugated metal barrier is used to isolate the sensor, then the sensor is protected from process fluid contact, but the structure adds complexity and potential failure points
Solution Approach 1:
By removing the inert oil fill, the patent simplifies the isolation structure to just the corrugated metal barrier. This eliminates the additional complexity of oil containment, sealing mechanisms, and associated failure points, while maintaining sensor protection through the robust metal barrier.
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 solution enables accurate pressure measurement up to 2000 psi and 275°C, with high sensitivity and stability, eliminating the need for external stress isolation and oil fills, making it suitable for size and weight-sensitive applications like aerospace, while preventing measurement errors from oil outgassing.
Implementation Method 1
A flexible diaphragm is disposed between the first and second support members. The diaphragm includes first and second opposing surfaces. The first opposing surface is in fluid communication with a first fluid-flow circuit, and the second opposing surface is in fluid communication with a second fluid-flow circuit.
Implementation Method 2
utilizing a silicon-on-insulator (SOI) substrate with strain-gauge and piezoelectric resistance-bridge sensing elements for accurate pressure measurement
Implementation Method 3
utilizing a silicon-on-insulator (SOI) substrate with strain-gauge and piezoelectric resistance-bridge sensing elements for accurate pressure measurement
Data Source
AI summary
A sensing apparatus for determining the pressure of a fluid includes first and second support members. The first and second support members are configured to define at least one sealed chamber. A flexible diaphragm is disposed between the first and second support members. The diaphragm includes first and second opposing surfaces. The first opposing surface is in fluid communication with a first fluid-flow circuit, and the second opposing surface is in fluid communication with a second fluid-flow circuit. A first electronic circuit is disposed within the at least one chamber and coupled to the diaphragm for sensing a first differential pressure associated with the first and second flow circuits. The first electronic circuit is configured to produce at least one electrical signal proportional to a magnitude of the first differential pressure.