WO1988001096A1 - Rotary signal coupler - Google Patents

Rotary signal coupler Download PDF

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Publication number
WO1988001096A1
WO1988001096A1 PCT/GB1987/000554 GB8700554W WO8801096A1 WO 1988001096 A1 WO1988001096 A1 WO 1988001096A1 GB 8700554 W GB8700554 W GB 8700554W WO 8801096 A1 WO8801096 A1 WO 8801096A1
Authority
WO
WIPO (PCT)
Prior art keywords
primary
rotary coupling
winding
member
primary winding
Prior art date
Application number
PCT/GB1987/000554
Other languages
French (fr)
Inventor
John Christopher Hale
Christopher Charles Harold Hale
Original Assignee
Contrology Products Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GB868619316A priority Critical patent/GB8619316D0/en
Priority to GB8619316 priority
Application filed by Contrology Products Limited filed Critical Contrology Products Limited
Publication of WO1988001096A1 publication Critical patent/WO1988001096A1/en

Links

Classifications

    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00Survey of boreholes or wells
    • E21B47/12Means for transmitting measuring-signals or control signals from the well to the surface or from the surface to the well, e.g. for logging while drilling
    • E21B47/122Means for transmitting measuring-signals or control signals from the well to the surface or from the surface to the well, e.g. for logging while drilling by electromagnetic energy, e.g. radio frequency
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00Adaptations of transformers or inductances for specific applications or functions
    • H01F38/14Inductive couplings
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00Adaptations of transformers or inductances for specific applications or functions
    • H01F38/18Rotary transformers

Abstract

Signals are coupled between a shaft (20) and a housing (22) which rotate relative to each other by means of a primary coil (24) inductively coupled with a secondary coil (26). The primary coil (24) has a relatively large extent (A) and the secondary coil has a much smaller extent (B) and is positioned at the centre of the primary (24). Suitably A/B 6.

Description

Rotary Signal Coupler

This invention relates to a coupling for transmitting electrical signals between first and second members which undergo relative rotation.

The invention is particularly, but not exclusively, of relevance to the inspection of long hollow cylindrical objects, such as drill collars for oil boreholes. A drill collar typically has a length of 10 m and an internal bore of about 78 mm; this makes iπ.ternal inspection for cracks and the like difficult- In our EP-A-0 033802 there is disclosed an electro.— magnetic inspection apparatus using a probe with twin windings. This apparatus is suitable for detecting defects of interest in drill collars and the like, but it is necessary to scan the probe over the internal surface. One way of doing this would be to draw through the bore on which the probe is rotatably mounted, so that spiral scan is performed. However, it is necessary to couple the signals from the rotating probe to a non-rotating instrument including a bridge circuit. Since the parameter of interest is a small out-of-balance quantity, it is very easy for this to be swamped by noise in the coupling. It has also been found that the signal of interest can be swamped by spurious signals arising from non-uniformity of rotational and translational movement.

Accordingly, an object of the present invention is to provide a coupling of the kind stated and which provides low noise and a high immunity to non-uniform movemen . The invention provides a rotary coupling for transferring an electrical signal between first and second members arranged to undergo relative rotation, comprising a primary winding on the first member, and a secondary winding on the second member adjacent the primary winding for inductive coupling therewith, the primary winding having a given linear extent and the secondary winding being positioned within a minor part of and spaced from the ends of said linear extent.

Preferably there are two primary and two secondary windings, both pairs being as specified in the preceding paragraph, for coupling two signals.

In a preferred form, the first member is a shaft and the second member a surrounding sleeve. The primary winding is a'single-layer coil of length A on the shaft surface, and the secondary a multi- ^0 layer coil of length B on the sleeve adjacent the centre of the primary. Suitably A/B 6.

Preferably, the face of the primary winding away from the secondary winding is covered with a ferrite material.

Embodiments of the invention will now be described, by way l ~- of example, with reference to the drawings, in which:-

Fig 1 is a perspective view of an inspection apparatus incorporating the invention;

Fig 2 is a diagrammatic cross-section of a coupling embodying the invention for use in the apparatus of Fig 1; 20 Fi 3 is a similar view of an alternative embodiment of the coupling; and

Fig 4 is a side view, partly in cross-section, of a further embodiment.

The inspection apparatus shown in Fig 1 comprises a cylindrical 25 body 10 dimensioned to be pulled through the bore of a tubular member by a cable 12. The body 10 has spring-biased wheels 14 for engagement with the bore. A probe 16, suitably of the type described in EP-A-0033802, is mounted in a holder 18 which is rotatable with respect to the body 10, to produce a helical scanning pattern. 30 Referring to Fig 2, the probe and holder are attached to a shaft 20 rotatable within a sleeve 22. The two windings of the probe 16 are connected each to a respective primary winding 24a, 24b, which are single-layer windings formed over ferrite layers 26a, 26b in circumferential grooves in the outer surface of the 35 shaft 20.

Each primary winding 24a, 24b is inductively coupled with a respective secondary winding 28a, 28b, these being multi-layer windings formed in narrow slots in the sleeve 22.

In accordance with the invention, the linear extent A of the primary windings 24 is considerably larger than the linear extent B of the secondary windings. The purpose is to position the secondary winding in an area of uniform flux from its primary, and to avoid coupling in the end zone of the primary where flux concentration occurs.

This minimises noise induced by axial movement between the shaft and the sleeve, or lack of concentricity in the rotational movement. It has been found that A/B _ 6 is suitable, and that

(while the coupling efficiency is poor) induced noise is very low.

The alternative embodiment shown in Fig 3 operates in a similar manner and like parts are denoted by like references. In this case, however, the primary windings 24 are disc-shaped in a transversely extending flange 30 and are coupled with secondary windings 28 in an annular housing 32. Bearings.34 journal the shaft 20 for rotation in the housing 32.

Fig 4 illustrates the invention applied to the inspection of a narrow-bore tube 40 having a bore too small to accept the rotary coupling. A probe 16 is mounted on the end of a rod 42 for rotation and translation within the tube 40. Bearing means indicated at 44 are provided for locating the probe 16 within the tube 40. The rod 42 is rotated b.y a drive assembly 46 embodying the coupling described above and located outside the tube 40. It will be understood that the rod 42 houses conductors connecting the probe 16 to the inductive coupling.

Preferably, the rod 42 is sectional, the sections being provided with mechanical screw or bayonet connectors and mating electrical contacts. This permits long tubing to be inspected with the drive assembly requiring axial movement only by the section length.

Claims

01096 '-4-CLAIMS :
1. A rotary coupling for transferring an electrical signal between first and second members arranged to undergo relative rotation, comprising a primary winding on the first member, and a secondary winding on the second member adjacent the primary winding for inductive coupling therewith, the primary winding having a given linear extent and the secondary winding being positioned within a minor part of and spaced from the ends of said linear extent..
2. A rotary coupling having two primary and twerrseeαπda-ry windings, arranged in pairs of a primary and a secondary winding, each pair being in accordance with claim ~.r. for coupling two signals.
3. A rotary coupling according to claim 1, in which the first member is a shaft and the second member is a sleeve.
4. A rotary coupling according to claim 3, in which the primary winding is a single—layer coil of length A on the shaft surface, and the secondary a multi-layer coil of length B on the sleeve adjacent the centre of the primary.
5. A rotary coupling according to claim 4, in which A:B is equal to or greater than 6.
6. A rotary coupling according to claim 1, in which the face of the primary winding away from the secondary winding is covered with a ferrite material.
PCT/GB1987/000554 1986-08-07 1987-08-03 Rotary signal coupler WO1988001096A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB868619316A GB8619316D0 (en) 1986-08-07 1986-08-07 Rotary signal coupler
GB8619316 1986-08-07

Publications (1)

Publication Number Publication Date
WO1988001096A1 true WO1988001096A1 (en) 1988-02-11

Family

ID=10602391

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1987/000554 WO1988001096A1 (en) 1986-08-07 1987-08-03 Rotary signal coupler

Country Status (3)

Country Link
EP (1) EP0277169A1 (en)
GB (1) GB8619316D0 (en)
WO (1) WO1988001096A1 (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0399987A1 (en) * 1989-05-23 1990-11-28 Smet-Hole, Naamloze Vennootschap Device and method for signal transmission in drill stems
FR2661511A1 (en) * 1990-04-27 1991-10-31 Geophysique Cie Gle Device for acquiring a seismic signal emitted by a rotating drilling bit (tool)
US5248857A (en) * 1990-04-27 1993-09-28 Compagnie Generale De Geophysique Apparatus for the acquisition of a seismic signal transmitted by a rotating drill bit
GB2280315A (en) * 1993-07-19 1995-01-25 Secr Defence Rotatable electric transformer coupling
WO1996000836A1 (en) * 1994-06-30 1996-01-11 Expro North Sea Limited Downhole data transmission
US6670880B1 (en) 2000-07-19 2003-12-30 Novatek Engineering, Inc. Downhole data transmission system
US6717501B2 (en) 2000-07-19 2004-04-06 Novatek Engineering, Inc. Downhole data transmission system
US6830467B2 (en) 2003-01-31 2004-12-14 Intelliserv, Inc. Electrical transmission line diametrical retainer
US7019665B2 (en) 2003-09-02 2006-03-28 Intelliserv, Inc. Polished downhole transducer having improved signal coupling

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3519969A (en) * 1968-11-12 1970-07-07 Caterpillar Tractor Co Rotating transformer
DE1920890A1 (en) * 1969-04-24 1970-11-12 Guenther Vogeler Slip ring-free inductive transformer and
GB2058475A (en) * 1979-08-31 1981-04-08 Westinghouse Electric Corp Inductive coupler
JPH06120308A (en) * 1992-10-09 1994-04-28 Toshiba Corp Test method for semiconductor wafer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3519969A (en) * 1968-11-12 1970-07-07 Caterpillar Tractor Co Rotating transformer
DE1920890A1 (en) * 1969-04-24 1970-11-12 Guenther Vogeler Slip ring-free inductive transformer and
GB2058475A (en) * 1979-08-31 1981-04-08 Westinghouse Electric Corp Inductive coupler
JPH06120308A (en) * 1992-10-09 1994-04-28 Toshiba Corp Test method for semiconductor wafer

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Vol. 10, No. 168 (E-411)(2224), 14 June 1986 see the whole document & JP, A, 6120308 (Pioneer K.K.) 29 January 1986 *

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0399987A1 (en) * 1989-05-23 1990-11-28 Smet-Hole, Naamloze Vennootschap Device and method for signal transmission in drill stems
WO1990014497A2 (en) * 1989-05-23 1990-11-29 Eastman Christensen Gmbh Process and device for transmitting data signals and/or control signals in a pipe train
WO1990014497A3 (en) * 1989-05-23 1991-01-10 Eastman Christensen Gmbh Process and device for transmitting data signals and/or control signals in a pipe train
FR2661511A1 (en) * 1990-04-27 1991-10-31 Geophysique Cie Gle Device for acquiring a seismic signal emitted by a rotating drilling bit (tool)
US5248857A (en) * 1990-04-27 1993-09-28 Compagnie Generale De Geophysique Apparatus for the acquisition of a seismic signal transmitted by a rotating drill bit
GB2280315A (en) * 1993-07-19 1995-01-25 Secr Defence Rotatable electric transformer coupling
WO1996000836A1 (en) * 1994-06-30 1996-01-11 Expro North Sea Limited Downhole data transmission
US6670880B1 (en) 2000-07-19 2003-12-30 Novatek Engineering, Inc. Downhole data transmission system
US6717501B2 (en) 2000-07-19 2004-04-06 Novatek Engineering, Inc. Downhole data transmission system
US6830467B2 (en) 2003-01-31 2004-12-14 Intelliserv, Inc. Electrical transmission line diametrical retainer
US7019665B2 (en) 2003-09-02 2006-03-28 Intelliserv, Inc. Polished downhole transducer having improved signal coupling

Also Published As

Publication number Publication date
GB8619316D0 (en) 1986-09-17
EP0277169A1 (en) 1988-08-10

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