Self-aligning core for induction coil

• US 5,039,970 A
• Filed: 05/17/1989
• Issued: 08/13/1991
• Est. Priority Date: 05/17/1989
• Status: Expired due to Fees

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Cox, Larry R.
• Primary Examiner(s): Kozma, Thomas J.
• Application Number:
  US07/353,455
• Time in Patent Office: 818 Days
• Field of Search: 336/175, 336/176, 336/212, 336/105, 336/107, 336/92, 324/127
• US Class Current: 336/107
• CPC Class Codes: G01R 1/22 Tong testers acting as secondary windings of current transformers

Abstract

An induction coil having two split-ring cores which are self-aligning. Each core is semi-circular, one core being fixed within a first jaw, and the other free to move within a second jaw. The jaws are pivotally attached and biased to form a closed loop in the relaxed state. A spring next to the free core urges the free core against the fixed core as the jaws are brought together. This action insures a proper contact between core ends which is necessary for optimum inductive coupling.

Claims

1. A device for inductively coupling a conductor to a receiver/transmitter, comprising:

a first jaw member;

a second jaw member pivotally attached to said first jaw member;

a first arcuate core member located within said first jaw member, said first arcuate core member having first and second ends, each of said ends extending outside of said first jaw member, said first arcuate core member being slidable along a path defined by the curve of said first arcuate core member;

a second arcuate core member located within said second jaw member, said second arcuate core member having first and second ends, each of said ends extending outside of said second jaw member;

first bias means for urging said ends of said first core member away from said first jaw member whereby, when said jaw members are brought together, said ends of said first core member forcibly abut said ends of said second core member; and

means for electrically coupling one of said first or second core members to the receiver/transmitter.

2. The device of claim 1 wherein said first bias means comprises spring means disposed between said core member and an inner wall of said first jaw member.

3. The device of claim 2 further comprising second bias means for urging said jaw members together.

4. The device of claim 3 further comprising:

a first handle member attached to said first jaw member; and

a second handle member attached to said second jaw member.

5. The device of claim 4 wherein said second core member is securely fixed within said second jaw member.

6. The device of claim 5 wherein said means for electrically coupling one of said first or second core members to the receiver/transmitter comprises:

jack means; and

a wire wrapped around said second core member forming at least one winding, said wire being electrically connected to said jack means.

7. The device of claim 6 further comprising fastening means for pivotally attaching said first and second jaw members, said fastening means including means for reducing friction between said first and second jaw members.

8. The device of claim 7 wherein:

said first jaw member has a plurality of o-ring seats therein; and

said first core member is inserted through a plurality of o-rings, said o-rings being situated in said o-ring seats, and said o-rings being lubricated to facilitate sliding movement of said first core member through said o-rings.

9. An induction coil comprising:

a first hollow, substantially semi-circular jaw having first and second ends, and having a plurality of o-ring seats therein;

a second hollow, substantially semi-circular jaw having first and second ends;

fastening means for pivotally attaching said first end of said first jaw to said first end of said second jaw, said fastening means including means for reducing friction between said first and second jaws;

a first semi-circular, electrically conductive core located within said first jaw, said first core having first and second ends, said first end of said first core extending beyond said first end of said first jaw, and said second end of said first core extending beyond said second end of said first jaw;

a plurality of o-rings situated in said o-ring seats of said first jaw, said first core being inserted through said o-rings;

a second semi-circular, electrically conductive core located within said second jaw, said second core having first and second ends, said first end of said second core extending beyond said first end of said second jaw, and said second end of said second core extending beyond said second end of said second jaw;

first bias means for urging said first core towards said second core whereby, when said second ends of said jaws are moved proximate one another, said ends of said first core forcibly abut said ends of said second core;

second bias means for urging said second ends of said jaws toward each other;

first handle means attached to said first jaw proximate said first end thereof;

second handle means attached to said second jaw proximate said first end thereof; and

means for electrically coupling said second core to an external receiver/transmitter.

10. The induction coil of claim 9 wherein one of said o-ring seats is located proximate a central portion of said first core, and said centrally located o-ring seat has a slot therein which is longer than the diameter of said o-rings, thereby allowing said first core to move transversely within said first jaw.

11. The induction coil of claim 10 wherein:

said second core is securely fixed within said second jaw; and

said first bias means comprises a leaf spring positioned between said first core and an inner wall of said first jaw, proximate said centrally located o-ring seat.

12. The induction coil of claim 11 wherein said means for electrically coupling said second core to the external receiver/transmitter comprises:

a jack attached to said second handle; and

a wire wrapped around said second core forming at least one winding, said wire being electrically connected to said jack.

13. The induction coil of claim 12 further comprising:

means for receiving an extension pole, said receiving means being attached to said first handle; and

means for remotely opening said jaws.

14. A split-ring, self-aligning induction coil for applying a trace signal to a wire, comprising:

a first hollow, semi-circular jaw having a first hub and a first integral handle proximate said hub, said first jaw being formed of a nonconductive, nonmagnetic material, and said first jaw having a plurality of o-ring seats therein;

a second hollow, semi-circular jaw whose size, shape and material are essentially identical to said first jaw, having a second hub and a second integral handle proximate said second hub;

fastening means for pivotally attaching said first jaw to said second jaw, said fastening means including means for reducing friction between said first and second hubs;

a first semi-circular core located within said first jaw, said first core being constructed of a laminated nickel alloy, and having first and second ends, each of said ends extending outside of said first jaw, said first core being inserted through a plurality of o-rings, said o-rings being situated in said o-ring seats, and said o-rings being lubricated to facilitate sliding movement of said first core through said o-rings, one of said o-ring seats further being located proximate a central portion of said first core, said centrally located o-ring seat having a slot therein which is longer than the diameter of said o-rings, thereby allowing said first core to move transversely within said first jaw;

a second semi-circular core located within said second jaw, said second core being constructed of a laminated nickel alloy, and having first and second ends, each of said ends extending outside of said second jaw, said second core being securely fixed within said second jaw;

a leaf spring positioned between said first core and an inner wall of said first jaw, proximate said centrally located o-ring seat, said leaf spring urging said first core towards said second core whereby, when said jaws are brought together, said ends of said first core forcibly abut said ends of said second core, forming a substantially circular closed loop;

a torsion spring for urging said jaws together, said torsion spring having first and second tines, said first tine being inserted in said first handle, and said second tine being inserted in said second handle;

a threaded insert attached to said first handle for receiving an extension pole;

a tab attached to said second jaw for receiving string means to remotely open said jaws;

a jack attached to said second handle; and

a wire wrapped around said second core forming at least one winding, said wire being electrically connected to said jack.