US5747696A
Expired / Lapsed
US
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Method of non-invasively monitoring pressure of a compressed gas in a closed container
Assignee: ZF Airbag Germany GmbH
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Filing: 1996-10-28
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Granted: 1998-05-05
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Expires: 2016-10-28
Abstract
Abstract A method for non-invasively monitoring a pressure of a compressed gas inside a closed container includes: forming a magnetic circuit through a portion of the outside wall of the container; detecting magnetic flux amplitude changes in the magnetic circuit created by a transient stress in the outside wall of the container; producing data representing the magnetic flux amplitude changes; and monitoring pressure changes from a nominal pressure by evaluating the data representing the magnetic flux amplitude changes.
Inventors
- 👤 Hegeon Kwun
- 👤 Michael Allen Piskie
- 👤 Tony Gioutsos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:22
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/16; Y; Y10; Y10S; Y10S73/00; Y10S73/02
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
92 words
A method for non-invasively monitoring a pressure of a compressed gas inside a closed container having an outside wall, comprising: forming a magnetic circuit through a portion of the outside wall of the container; generating a transient stress in the outside wall of the container; detecting magnetic flux amplitude changes in the magnetic circuit created by the transient stress in the outside wall of the container; producing data representing the magnetic flux amplitude changes; and monitoring pressure changes from a nominal pressure by evaluating the data representing the magnetic flux amplitude changes.
Claim 2
Independent Claim
92 words
A method for non-invasively monitoring a pressure of a compressed gas inside a closed container having an outside wall, comprising: forming a magnetic circuit through a portion of the outside wall of the container; generating a transient stress in the outside wall of the container; detecting magnetic flux amplitude changes in the magnetic circuit created by the transient stress in the outside wall of the container; producing data representing the magnetic flux amplitude changes; and monitoring pressure changes from a nominal pressure by evaluating the data representing the magnetic flux amplitude changes.
Claim 3
Dependent Claim
51 words
The method according to claim 1, wherein the monitoring step includes: converting the data to frequency domain data; detecting a peak frequency from the frequency domain data; and comparing the peak frequency with a calibrated frequency corresponding to the nominal pressure to determine a variation in pressure from the nominal pressure.
Claim 4
Dependent Claim
16 words
The method according to claim 2, wherein the converting step includes fast fourier transforming the data.
Claim 5
Dependent Claim
30 words
The method according to claim 1, wherein the comparing step includes comparing the peak frequency with a calibrated frequency which corresponds to a 0% pressure drop from the nominal frequency.
Claim 6
Dependent Claim
27 words
The method according to claim 1, wherein the generating step includes applying a mechanical impact to the outside wall of the container for generating the transient stress.
Claim 7
Dependent Claim
26 words
The method according to claim 5, wherein the applying step includes dropping a ball bearing onto the outside wall of the container from a predetermined height.
Claim 8
Dependent Claim
51 words
The method according to claim 1, wherein the forming step includes using a magnetostrictive sensor that includes a magnet and placing the magnetostrictive sensor on the outside wall of the container for forming the magnetic circuit and the detecting step includes using the magnetostrictive sensor for detecting the magnetic flux changes.
Claim 9
Dependent Claim
41 words
The method according to claim 7, wherein the magnetostrictive sensor includes a magnet having a U-shaped cross-section presenting first and second legs and a wire forming first and second windings disposed on the first and second legs, respectively, of the magnet.
Claim 10
Dependent Claim
35 words
The method according to claim 7, wherein the magnetostrictive sensor has a curved bottom surface and the placing step includes placing the curved bottom surface of the magnetostrictive sensor on the wall of the container.
Claim 11
Independent Claim
135 words
A method for non-invasively monitoring a pressure of a compressed gas inside a closed container having an outside wall, comprising: forming a magnetic circuit through a portion of the outside wall of the container; detecting magnetic flux amplitude changes in the magnetic circuit created by a transient stress in the outside wall of the container due to rapid depressurization of the container; producing data representing the magnetic flux amplitude changes; converting the data into an energy waveform that represents a measure of energy and evaluating the energy waveform; low pass filtering the energy waveform; and evaluating a performance of the depressurization of the container by determining an interval between a point in time from initiation of the rapid depressurization to a point in time at which the energy waveform first reaches a predetermined energy level.
Claim 12
Independent Claim
135 words
A method for non-invasively monitoring a pressure of a compressed gas inside a closed container having an outside wall, comprising: forming a magnetic circuit through a portion of the outside wall of the container; detecting magnetic flux amplitude changes in the magnetic circuit created by a transient stress in the outside wall of the container due to rapid depressurization of the container; producing data representing the magnetic flux amplitude changes; converting the data into an energy waveform that represents a measure of energy and evaluating the energy waveform; low pass filtering the energy waveform; and evaluating a performance of the depressurization of the container by determining an interval between a point in time from initiation of the rapid depressurization to a point in time at which the energy waveform first reaches a predetermined energy level.
Claim 13
Dependent Claim
14 words
The method according to claim 10, wherein the converting step includes squaring the data.
Claim 14
Dependent Claim
69 words
The method according to claim 10, and further including the step of generating a mechanical stress in the outside wall of the container, and wherein the evaluating step includes detecting a peak amplitude of the energy waveform created as a result the generating step and determining a variation in pressure from a nominal pressure by comparing the peak amplitude with a calibrated amplitude that corresponds to the nominal pressure.
Claim 15
Dependent Claim
27 words
The method according to claim 12, wherein the generating step includes applying a mechanical impact to the outside wall of the container for generating the transient stress.
Claim 16
Dependent Claim
26 words
The method according to claim 13, wherein the applying step includes dropping a ball bearing onto the outside wall of the container from a predetermined height.
Claim 17
Dependent Claim
30 words
The method according to claim 12, wherein the comparing step includes comparing the peak amplitude with a calibrated amplitude which corresponds to a 0% pressure drop from the nominal pressure.
Claim 18
Dependent Claim
51 words
The method according to claim 10, wherein the forming step includes using a magnetostrictive sensor that includes a magnet and placing the magnetostrictive sensor on the outside wall of the container for forming the magnetic circuit and the detecting step includes using the magnetostrictive sensor for detecting the magnetic flux changes.
Claim 19
Dependent Claim
41 words
The method according to claim 16, wherein the magnetostrictive sensor includes a magnet having a U-shaped cross-section presenting first and second legs and a wire forming first and second windings disposed on the first and second legs, respectively, of the magnet.
Claim 20
Dependent Claim
35 words
The method according to claim 16, wherein the magnetostrictive sensor has a curved bottom surface and the placing step includes placing the curved bottom surface of the magnetostrictive sensor on the wall of the container.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-05-04 | 2001-11-03 | 2002-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-05-04 | 2005-11-03 | 2006-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-05-04 | 2009-11-03 | 2010-05-05 | $7700.00 | Window Closed / Lapsed |