US3876927A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic sensor with shorted turn
Assignee: Electro Corp
•
Filing: 1973-12-20
•
Granted: 1975-04-08
•
Expires: 1993-12-20
Abstract
Abstract A magnetic pickup for sensing movement of a body of magnetic material. The pickup includes a coil having a shorted turn to limit the amplitude of the output signal which would otherwise occur at high movement rates. The pickup has a pole piece extending through the coil, with a conductive sleeve surrounding the pole piece. Limitation of the output signal amplitude enables use of the sensor in an explosive environment. The conductive sleeve also reduces the susceptibility of the sensor to interference from stray fields.
Inventors
- 👤 Gordon E Gee
- 👤 Frank J Blakeley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:56
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/488
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
127 words
A magnetic sensor for sensing the movement of a body of magnetic material comprising: a permanent magnet; a pole piece of magnetic material extending from said magnet; a coil around said pole piece, the magnetic flux through said pole piece linking said coil and being subject to a change in magnitude upon relative movement between the sensor and said body of magnetic material in the field extending from the pole piece, inducing a voltage in said coil; and a shorted turn operably associated with said coil, said turn designed to substantially reduce the rate of increase of signal voltage induced in said coils as a function of the speed of the body being sensed and thereby appreciably limiting the amplitude of the voltage induced in the coil.
Claim 2
Dependent Claim
127 words
A magnetic sensor for sensing the movement of a body of magnetic material comprising: a permanent magnet; a pole piece of magnetic material extending from said magnet; a coil around said pole piece, the magnetic flux through said pole piece linking said coil and being subject to a change in magnitude upon relative movement between the sensor and said body of magnetic material in the field extending from the pole piece, inducing a voltage in said coil; and a shorted turn operably associated with said coil, said turn designed to substantially reduce the rate of increase of signal voltage induced in said coils as a function of the speed of the body being sensed and thereby appreciably limiting the amplitude of the voltage induced in the coil.
Claim 3
Dependent Claim
19 words
The magnetic sensor of claim 1 in which said shorted turn is a conductive sleeve coaxial with said coil.
Claim 4
Dependent Claim
20 words
The magnetic sensor of claim 2 in which said conductive sleeve is located between the coil and said pole piece.
Claim 5
Dependent Claim
19 words
The magnetic sensor of claim 3 in which said conductive sleeve is in physical contact with the pole piece.
Claim 6
Dependent Claim
95 words
The magnetic sensor of claim 4 wherein said permanent magnet has an end portion, said pole piece is cylindrical and extends from said end portion, and has a cross sectional dimension less than that of the magnet, said coil is wound on a bobbin having an axial opening through which said pole piece extends, and said conductive sleeve surrounds said pole piece, inside the axial opening of said bobbin and in physical contact with said pole piece, whereby heat generated in said sleeve is at least in part dissipated in said pole piece and magnet.
Claim 7
Dependent Claim
26 words
The magnetic sensor of claim 2 in which said conductive sleeve is of a material having a conduction characteristic of the order of that of copper.
Claim 8
Dependent Claim
130 words
In a magnetic sensor having a magnet, a pole piece and a coil around said pole piece subject to a change in the magnitude of a magnetic flux from the magnet linking the turns of the coil, upon relative movement to be sensed between the coil and a body of magnetic material, the improvement comprising: a cylindrical sleeve defining a shorted turn around said polepiece having an outside diameter less than that of the coil, said sleeve being made from a material with a conductivity on the order of that of copper and designed to substantially reduce the rate of increase of signal voltage induced in said coil as a function of the speed of the body being sensed and thereby limiting the amplitude of the voltage in the coil.
Claim 9
Dependent Claim
130 words
In a magnetic sensor having a magnet, a pole piece and a coil around said pole piece subject to a change in the magnitude of a magnetic flux from the magnet linking the turns of the coil, upon relative movement to be sensed between the coil and a body of magnetic material, the improvement comprising: a cylindrical sleeve defining a shorted turn around said polepiece having an outside diameter less than that of the coil, said sleeve being made from a material with a conductivity on the order of that of copper and designed to substantially reduce the rate of increase of signal voltage induced in said coil as a function of the speed of the body being sensed and thereby limiting the amplitude of the voltage in the coil.
Claim 10
Dependent Claim
15 words
The magnetic sensor of claim 7 in which said cylindrical sleeve is inside said coil.
Claim 11
Dependent Claim
110 words
In a magnetic sensor having a magnet and a coil within which a signal is induced in response to the time rate of change of flux from the magnet linking the coil, the improvement comprising: a shorted turn operatively associated with said coil such that it is linked by flux linking said coil, said shorted turn having a loop resistance sufficiently low to render substantially nonlinear the relationship between the time rate of change of flux and the amplitude of the signal induced thereby, said amplitude increasing with the time rate of change of flux less rapidly at faster rates of flux change than at slower rates of flux change.
Claim 12
Dependent Claim
110 words
In a magnetic sensor having a magnet and a coil within which a signal is induced in response to the time rate of change of flux from the magnet linking the coil, the improvement comprising: a shorted turn operatively associated with said coil such that it is linked by flux linking said coil, said shorted turn having a loop resistance sufficiently low to render substantially nonlinear the relationship between the time rate of change of flux and the amplitude of the signal induced thereby, said amplitude increasing with the time rate of change of flux less rapidly at faster rates of flux change than at slower rates of flux change.
Claim 13
Dependent Claim
15 words
The magnetic sensor of claim 9 in which said shorted turn is a single turn.
Claim 14
Dependent Claim
18 words
The magnetic sensor of claim 10 in which said shorted turn is a cylindrical sleeve of conductive material.
Claim 15
Dependent Claim
12 words
The magnetic sensor of claim 11 in which said sleeve is copper.
Claim 16
Dependent Claim
30 words
The magnetic sensor of claim 9 having a core inside said coil and forming a pole piece for the sensor, said shorted turn being between said coil and said core.
Claim 17
Dependent Claim
26 words
The magnetic sensor of claim 9 in which said shorted turn is made from a material having a resistivity on the order of that of copper.
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) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |