EP0136238B1
Expired / Lapsed
EP
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Device for measuring the proximity of a metallic conductive surface
Assignee: Commissariat à l'Énergie Atomique et Aux Énergies Alternatives
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Filing: 1984-09-25
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Granted: 1989-03-08
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Expires: 2004-09-25
Abstract
No abstract record available.
Inventors
- 👤 Henri Clergeot
- 👤 Jean-Marie Detriche
- 👤 François Monteil
- 👤 Dominique Placko
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 18:13
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/28; G01B7/287; B; B23; B23K; B23K9/00; B23K9/12; B23K9/127; B23K9/1272; B23K9/1276
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
279 words
Apparatus for measuring the distance from a conductive metal surface comprising at least one eddy cyrrent transducer (C 1 ,...C i , C µ ; C' 1 ,...C' i ,...C' n ) positioned facing the surface, each transducer having at least one coil (40; 41', 43'a, 43'b), a source (10) of sinusoidal voltage (U) supplying said transducer and supplying a sinusoidal voltage, whose frequency exceeds 100 kHz, and means (20, 22, 24) for processing the sinusoidal signal (U;) supplied by the transducer, said processing means comprising detection means sensitive to a reference signal (U c ) supplied by an oscillator (18), said reference signal (U c ) having the same frequency and being phase shifted by a given angle (β) with respect to said sinusoidal voltage (U), characterized in that the detection means are synchronous detection means (20, 22) for measuring only the inductive component of the impedance of the coil, means (62 to 70) being provided for automatically correcting the amplitude and the continuous component of the sinusoidal signal supplied by the transducer, said correction means comprising memories (66, 70) in which are recorded the corrections to be made, the apparatus also comprising at least one control transducer (Cp) placed in a fixed position with respect to a reference surface (45), said transducer being connected to the memories (66, 70) in such a way that the evolution of its characteristics makes it possible to correct the contents of the memories, the signal supplied by the synchronous detection means being introduced into an analog - digital converter (60) and the digital signals supplied by converter (60) addressing a digital linearization memory (72) in which is recorded a calibration curve.
Claim 2
Dependent Claim
279 words
Apparatus for measuring the distance from a conductive metal surface comprising at least one eddy cyrrent transducer (C 1 ,...C i , C µ ; C' 1 ,...C' i ,...C' n ) positioned facing the surface, each transducer having at least one coil (40; 41', 43'a, 43'b), a source (10) of sinusoidal voltage (U) supplying said transducer and supplying a sinusoidal voltage, whose frequency exceeds 100 kHz, and means (20, 22, 24) for processing the sinusoidal signal (U;) supplied by the transducer, said processing means comprising detection means sensitive to a reference signal (U c ) supplied by an oscillator (18), said reference signal (U c ) having the same frequency and being phase shifted by a given angle (β) with respect to said sinusoidal voltage (U), characterized in that the detection means are synchronous detection means (20, 22) for measuring only the inductive component of the impedance of the coil, means (62 to 70) being provided for automatically correcting the amplitude and the continuous component of the sinusoidal signal supplied by the transducer, said correction means comprising memories (66, 70) in which are recorded the corrections to be made, the apparatus also comprising at least one control transducer (Cp) placed in a fixed position with respect to a reference surface (45), said transducer being connected to the memories (66, 70) in such a way that the evolution of its characteristics makes it possible to correct the contents of the memories, the signal supplied by the synchronous detection means being introduced into an analog - digital converter (60) and the digital signals supplied by converter (60) addressing a digital linearization memory (72) in which is recorded a calibration curve.
Claim 3
Dependent Claim
31 words
Apparatus according to claim 1, characterized in that said source (10) comprises a second oscillator (26) and means (18, 30 to 36) for controlling said oscillator as regards amplitude and freqyency.
Claim 4
Dependent Claim
86 words
Apparatus according to either of the claims 1 and 2, characterized in that the coil (40) of the transducer (C 1 ,... C i ,... C n ) is mounted on a U-shaped magnetic circuit (38) open in the direction of said surface, said source (10) being directly connected to the terminals of the coil and the sinusoidal signal (u;) supplied by the transuducer being obtained from the current (i i ) passing through the coil by means of a low input impedance current-voltage transformer (52).
Claim 5
Dependent Claim
112 words
Apparatus according to any one of the claims 1 to 3, characterized in that the transducer (C' 1 ,..., C' i ,... C' n ) comprises an E-shaped magnetic circuit (38') open in the direction of said surface, and emitting coil (41') mounted on one of the end branches (42'a) and a receiving coil (43'a, 43'b) partly wound onto the other end branch (42'b) and partly onto the intermediate branch (42'c), said source (10) being connected to the terminals of the emitting coil (41') and the sinusoidal signal (u;) supplied by the transducer being obtained by placing in opposition the signals induced in the two parts (43'a, 43'b) of the receiving coil.
Claim 6
Dependent Claim
117 words
Apparatus according to any one of the claims 1 to 4, characterized in that the transducer (C" 1 ,... C" i .... C" n ) comprises an H-shaped magnetic circuit (38"), an exciting coil (41") mounted on the intermediate branch (38"a) of the magnetic circuit, a receiving coil (43") mounted on the end branches (38" b , 38" c ) of the magnetic circuit and the conductive reference surface (45) located at a given distance from the ends of the end branches (38" b , 38" c ) located on the side opposite to the surface (s) whose distance it is desired to measure, said source (10) being connected to the terminals of the exciting coil (41").
Claim 7
Dependent Claim
86 words
Apparatus according to any one of the claims 1 to 5, applied to the detection of the profile of a conductive metal surface, characterized in that it comprises at least one row of aligned eddy current transducers (C 1 ,... C i ,... C n ; C' 1 ,... C' i ,... C' n ), said source (10) simultaneously supplying the transducers, multiplexing means (14) being provided for successively injecting into the processing means (20, 22, 24) each of the signals (u;) supplied by the transducers.
Claim 8
Dependent Claim
70 words
Apparatus according to claim 6, characterized in that it comprises several juxtaposed elementary transducers (C i , C' i ), each elementary transducer having at least one eddy current coil mounted on a magnetic circuit (38, 38') open in the direction of a metal object whose distance it is desired to measure, the elementary transducers being juxtaposed in such a way that their magnetic circuits are located in parallel planes.
Claim 9
Dependent Claim
27 words
Apparatus according to claim 7, characterized in that the transducers (C 1 , C' i ) are separated and surrounded by metal plates (44, 46; 44', 46').
Claim 10
Dependent Claim
28 words
Apparatus according to claim 8, characterized in that the parallel branches polarized in opposite directions of each of the transducers are separated by a metal plate (50, 50').
References Cited (Backward Citations)
No citation records indexed.
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