US4720676A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetomechanical transducer utilizing resonant frequency shifts to measure pressure in response to displacement of a pressure sensitive device
Assignee: Honeywell International Inc
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Filing: 1983-12-05
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Granted: 1988-01-19
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Expires: 2003-12-05
Abstract
Abstract A target adapted for use in a magnetomechanical transducer system is activated by an ac magnetic field and a variable dc bias field to produce a resonant frequency which corresponds to the effective strength of the dc bias field. The target includes an elongated ductile strip of magnetostrictive ferromagnetic material enclosed in a nonmagnetic container in a manner to allow the strip to vibrate freely. The strip has a magnetomechanical coupling factor, k greater than O, where K=zero 2ROOT (1-fr2/fa2), fr and fa being the resonant and antiresonant frequencies, respectfully. The system is economical to construct and affords accurate and efficient measurement of pressure via displacements and angles of pressure sensitive devices at locations proximate to or remote from the signal source (target).
Inventors
- 👤 Philip M. Anderson, III
- 👤 Jeffrey C. Urbanski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:13
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/12; G01D5/243; G01L; G01L9/00; G01L9/0026; G01L9/0029
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
165 words
A magnetomechanical-resonant-frequency pressure transducer system responsive to the strength of a d.c. bias field on a target, comprising: a. means including a driving coil co-axial with said target for interrogating said target, b. generating means for generating an a.c. magnetic field within said coil to effect direct magnetic coupling between said ac magnetic field and said target, said ac magnetic field incorporating the resonant frequency of said target; c. means including a displaceable pressure sensitive device biasing means for generating said dc bias field and varying means for changing the relative displacement of said pressure sensitive device and said target so as to vary the strength of said dc bias field on said target, thereby applying a variable d.c. bias field to said target to produce changes in the resonant frequency of said target that are correlated with displacement of said pressure sensitive device; and d. detection means for detecting the resonant frequency produced in said target by the strength of said dc bias field.
Claim 2
Dependent Claim
165 words
A magnetomechanical-resonant-frequency pressure transducer system responsive to the strength of a d.c. bias field on a target, comprising: a. means including a driving coil co-axial with said target for interrogating said target, b. generating means for generating an a.c. magnetic field within said coil to effect direct magnetic coupling between said ac magnetic field and said target, said ac magnetic field incorporating the resonant frequency of said target; c. means including a displaceable pressure sensitive device biasing means for generating said dc bias field and varying means for changing the relative displacement of said pressure sensitive device and said target so as to vary the strength of said dc bias field on said target, thereby applying a variable d.c. bias field to said target to produce changes in the resonant frequency of said target that are correlated with displacement of said pressure sensitive device; and d. detection means for detecting the resonant frequency produced in said target by the strength of said dc bias field.
Claim 3
Dependent Claim
32 words
A resonant-frequency transducer system as recited in claim 1, wherein said generation means includes the use of a self-oscillating circuit having a reference frequency equal to the resonant frequency of said target.
Claim 4
Dependent Claim
44 words
A resonant-frequency transducer system as recited in claim 1, wherein said generation means includes energizing means adapted to provide said interrogation coil with a white noise source comprising a uniform closely banded spectrum of ac magnetic fields incorporating the resonant frequency of said target.
Claim 5
Dependent Claim
32 words
A resonant-frequency transducer system as recited in claim 1, wherein said means for applying a variable d.c. bias field includes means for slideably displacing said target within a channel of ferrimagnetic material.
Claim 6
Dependent Claim
31 words
A resonant-frequency transducer system as recited in claim 1 wherein said means for applying a variable dc bias includes means for slideably displacing said target within a channel of ferromagnetic material.
Claim 7
Dependent Claim
60 words
A resonant-frequency transducer system as recited in claim 1, wherein said means for applying variable d.c. bias field includes a bar magnet adapted to generate a dc bias field, said bar magnet being mounted on a support in the proximity of said target for movement relative to said target to vary the strength of the dc bias field applied thereto.
Claim 8
Dependent Claim
36 words
A resonant-frequency transducer system as recited in claim 6, wherein said pressure sensitive device is a bourdon tube and said support on which said bar magnet is mounted comprises the free end of said bourdon tube.
Claim 9
Dependent Claim
25 words
A resonant-frequency transducer system as recited in claim 6, wherein said magnet bar is mounted for rotation about the X, Y or Z axes thereof.
Claim 10
Dependent Claim
32 words
A resonant-frequency transducer system as recited in claim 1, wherein said means for detection of said target's resonant frequency includes a counter having variable sensitivity and a receiving coil surrounding said target.
Claim 11
Dependent Claim
33 words
A resonant-frequency transducer system as recited in claim 1, wherein said means for applying a variable dc bias field comprises a barium-ferrite channel adapted, when magnetized, to provide said the dc bias field.
Claim 12
Dependent Claim
65 words
A resonant-frequency transducer system as recited in claim 1, wherein said target comprises an elongated, ductile strip of magnetostrictive ferromagnetic material enclosed in a non-magnetic container in such a manner as to allow the strip to vibrate freely, said strip having a magnetostrictive coupling factor, k greater than 0, where k=√(1-fr 2 /fa 2 ), fr and fa being the resonant and anti-resonant frequencies, respectively.
Claim 13
Dependent Claim
22 words
A resonant-frequency transducer system as recited in claim 10, wherein said barium-ferrite channel has a ferrite/plastic weight ratio of 0.25 to 0.30.
Claim 14
Dependent Claim
25 words
A resonant-frequency transducer system as recited in claim 12, wherein said channel is so constructed that said target is slidable therewithin for movement longitudinal thereof.
References Cited (Backward Citations)
US3706026A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-01-18 | 1991-07-20 | 1992-01-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-18 | 1995-07-20 | 1996-01-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-18 | 1999-07-20 | 2000-01-19 | $7700.00 | Window Closed / Lapsed |