US3774451A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluid pressure transducers
Assignee: ZF International UK Ltd
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Filing: 1972-04-11
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Granted: 1973-11-27
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Expires: 1992-04-11
Abstract
Abstract A fluid pressure transducer has a tube of magnetic material which can be subjected internally to a fluid pressure. Electromagnetic stators provide a rotating magnetic field which causes radial displacement of areas of the tube. Sensors surround the tube to detect radial displacement and an associated circuit causes the magnetic field to rotate at the resonant frequency of the tube. This resonant frequency is dependent on the pressure within the tube.
Inventors
- 👤 A Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:04
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0001; G01L9/0008
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
106 words
A fluid pressure transducer comprising a sealed tube of ferromagnetic material and having an inlet for fluid, a plurality of electromagnetic means arranged around the tube and each acting to impart radial displacement to the adjacent portion of the tube, a plurality of capacitive sensing devices around the tube each arranged to detect radial displacement of the adjacent portion of the tube and an electrical circuit responsive to signals received from said sensing devices and connected to said electromagnetic means to create a rotating magnetic field, rotating at a frequency at which the tube resonates, said frequency being dependent on the fluid pressure within the tube.
Claim 2
Dependent Claim
106 words
A fluid pressure transducer comprising a sealed tube of ferromagnetic material and having an inlet for fluid, a plurality of electromagnetic means arranged around the tube and each acting to impart radial displacement to the adjacent portion of the tube, a plurality of capacitive sensing devices around the tube each arranged to detect radial displacement of the adjacent portion of the tube and an electrical circuit responsive to signals received from said sensing devices and connected to said electromagnetic means to create a rotating magnetic field, rotating at a frequency at which the tube resonates, said frequency being dependent on the fluid pressure within the tube.
Claim 3
Dependent Claim
57 words
A fluid pressure transducer as claimed in claim 1 in which each electromagnetic means is associated with a corresponding one of the capacitive pick-up devices angularly spaced around the axis of the tube therefrom so that the electrical signal applied to said electromagnetic means is in phase with the electrical signal picked up by the pick up-device.
Claim 4
Dependent Claim
29 words
A fluid pressure transducer as claimed in claim 2 in which the angular spacing between each electromagnetic means and the corresponding pick up device is between 60* and 75*.
Claim 5
Dependent Claim
42 words
A fluid pressure transducer as claimed in claim 1 in which the electromagnetic means include polarising magnets and windings such that the field applied by the windings is at all times of smaller magnitude than the field applied by the polarising magnets.
Claim 6
Dependent Claim
17 words
A fluid pressure transducer as claimed in claim 4 in which the polarising magnets are permanent magnets.
Claim 7
Dependent Claim
64 words
A fluid pressure transducer as claimed in claim 7 in which the electromagnetic means comprises an inner stator mounted within the tube and having twelve outwardly directed pole faces, an outer stator mounted outside the tube and having twelve inwardly directed pole faces adjacent the outwardly directed pole faces respectively, and members of ferromagnetic material carrying said stators and separated by the polarising magnets.
Claim 8
Dependent Claim
31 words
A fluid pressure transducer as claimed in claim 6 in which said polarising magnets are located in bores in a Ring of non-magnetic material interposed between said members of ferromagnetic material.
Claim 9
Dependent Claim
51 words
A fluid pressure transducer as claimed in claim 7 in which said member of ferromagnetic material comprise a body including a disc portion, on which said ring is mounted, and a stem portion, on which said inner stator is mounted, and a sleeve abutting the ring and carrying the outer stator.
Claim 10
Dependent Claim
42 words
A fluid pressure transducer as claimed in claim 5 in which the windings are connected in a three phase four pole distribution with each phase winding of the outer stator connected in series with the corresponding phase winding of the inner stator.
Claim 11
Dependent Claim
23 words
A fluid pressure transducer as claimed in claim 9 in which diametrically opposite ones of the capacitive sensing devices are connected in parallel.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |