Fluid cooled litz coil inductive heater and connector therefor

• US 5,461,215 A
• Filed: 03/17/1994
• Issued: 10/24/1995
• Est. Priority Date: 03/17/1994
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Haldeman, Charles W.
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US08/210,047
• Time in Patent Office: 586 Days
• Field of Search: 219/677, 219/672, 219/674, 219/673, 219/632, 219/670, 174/15.6, 174/90, 336/60, 336/57, 439/190, 439/196, 439/485, 439/486
• US Class Current: 219/677
• CPC Class Codes: H05B 6/42 Cooling of coils

Abstract

A fluid cooled RF transmission cable, transformer primary or secondary winding, and induction heating coil incorporating litz cable is disclosed. The heating coil comprises: a litz cable including a bundle of mutually electrically insulated, intermixed wire filaments, and a coolant tube, surrounding the litz wire, for conveying a fluid for removing heat generated by the litz cable. Also a combined coolant and electrical connector for providing an electrical connection and coolant to an inductive heating coil including a coolant tube and a litz cable housed inside the coolant tube is described. The connector comprises a tubular conductive member having an inner bore extending through the member, a distal end of the member sealably joining a terminal end of the coolant tube, to place the inner bore in communication with inside of the coolant tube, the litz cable extending into the inner bore and terminating in a low resistance electrical connection to the member, a proximal end of the member adapted for connection to one of a coolant source and a coolant intake.

Claims

1. An induction coil for generating a time varying magnetic field to induce electric current formation in an electrically conducting substance, the coil comprising:

a litz cable comprising a bundle of mutually electrically insulated wire filaments;

a coolant tube, surrounding the litz cable and extending substantially parallel with the litz cable, for conveying a fluid for removing heat generated by the litz cable; and

at least one connector including;

a tubular conductive member sealably joining the coolant tube, the tubular member having an axial bore in fluid communication with the coolant tube and having at least one radial hole extending through a side wall of the tubular member into the axial bore, the litz cable extending into the bore, through the radial hole, and electrically connecting to the tubular member.

2. An induction coil as claimed in claim 1, wherein the insulated wire filaments are loosely bound in the coolant tube.

3. An induction coil as claimed in claim 1, wherein the coolant tube is constructed of a flexible resin.

4. An induction coil as claimed in claim 1, wherein the wire filaments are not mechanically bound to each other in a resin matrix.

5. An induction coil as claimed in claim 1, wherein the tubular conductive member is adapted to be connected to an electrical fitting supplying the fluid.

6. An induction coil as claimed in claim 5, wherein the litz cable is divided into plural bundles of the wire filaments and the bundles are separately drawn through different ones of plural radial holes.

7. An induction coil as claimed in claim 6, wherein the bundles are electrically connected to an outer surface of the tubular conductive member.

8. An induction coil as claimed in claim 7, wherein the bundles as soldered to the outer surface.

9. An induction coil as claimed in claim 8, wherein the solder is used to seal the radial holes.

10. An induction coil as claimed in claim 5, further comprising a flare nut fitting over a terminal end of the tubular conductive member to sealably join the tubular conductive member to the electrical fitting.

11. An induction as in claim 1, wherein the coolant tube is Quartz glass.

12. An induction coil as in claim 1, wherein the coolant tube includes an external braid of ceramic fiber.

13. An induction coil as in claim 1, wherein the coolant tube extends over an enlarged end of the tubular member and is held in place by a ferrule.

14. An induction coil as in claim 1, further comprising:

a second litz cable magnetically coupled to the first litz cable and comprising a bundle of mutually electrically insulated wire filaments; and

a second coolant tube surrounding the second litz cable for conveying a fluid for removing heat generated by the second litz cable.

15. An induction coil as claimed in claim 14, wherein the insulated wire filaments are loosely bound in the first litz cable and the second litz cable.

16. A combined coolant and electrical connector for providing an electrical connection and coolant to an inductive heating coil including a coolant tube and a conductive multi-filament litz cable housed inside of the coolant tube, the connector comprising a tubular conductive member having an inner bore extending through the member and having plural axial holes extending through a side wall of the member, a distal end of the member sealably joining a terminal end of the coolant tube to place the inner bore in communication with an inside of the coolant tube, the multi-filament litz cable extending into the inner bore, and separate bundles of the filaments extending through the plural axial holes and terminating in a low resistance electrical connection to the member, a distal end of the member adapted for connection to one of the coolant source and a coolant intake.