Self-regulating heater with integral induction coil and method of manufacture thereof

• US 5,087,804 A
• Filed: 12/28/1990
• Issued: 02/11/1992
• Est. Priority Date: 12/28/1990
• Status: Expired due to Term

• Current Assignee: Delaware Capital Formation Incorporated (Dover Corporation)
• Original Assignee: Metcal Incorporated (Dover Corporation), AMP Incorporated (Johnson Controls International plc)
• Inventors: McGaffigan, Thomas H.
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US07/635,790
• Time in Patent Office: 410 Days
• Field of Search: 219/10.43, 219/10.41, 219/9.5, 219/10.53, 219/10.75, 219/10.79, 29/602.1
• US Class Current: 219/618
• CPC Class Codes: H05B 2206/023 using the curie point of the material in which heating current is being generated to control the heating temperature
• CPC Class Codes: H05B 6/106 in the form of fillings
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

A self-regulating heater including a body of electrically non-conductive material, an induction coil embedded within the body, lossy heating particles dispersed within the body and connection terminals for supplying power to the induction coil. The lossy heating particles produce heat when subjected to an alternating magnetic field produced by the induction coil. The lossy heating particles have a Curie temperature approximately equal to a substantially constant auto-regulation temperature at which the body is heated. The connection terminals supply power to the induction coil so that the induction coil can produce an alternating magnetic field of sufficient intensity to cause the lossy heating particles to heat the body to the auto-regulation temperature. A method of manufacturing a self-regulating heater including providing a body of an electrically non-conductive material, providing an induction coil embedded within the body, providing lossy heating particles dispersed within the body, and providing connection terminals for supplying power to the induction coil. The induction coil can be embedded within the body by molding the material containing lossy heating particles around the induction coil.

Claims

1. A self-regulating heater, comprising:

a body comprising electrically non-conductive material;

an internal induction coil embedded within the body;

lossy heating particles dispersed within the body, the lossy heating particles producing heat when subjected to an alternating magnetic field produced by the internal induction coil, the lossy heating particles having a Curie transition temperature approximately equal to an auto-regulation temperature at which the body is heated; and

connection means for supplying power to the internal induction coil so that the induction coil can produce an alternating magnetic field of sufficient intensity to cause the lossy heating particles to heat the body to the auto-regulation temperature.

2. The heater of claim 1, wherein the lossy heating particles comprise ferrites.

3. The heater of claim 1, wherein the electrically non-conductive material comprises an elastomer, rubber or gel-type material.

4. The heater of claim 1, wherein the lossy heating particles comprise ferrimagnetic particles.

5. The heater of claim 1, wherein the lossy heating particles comprise ferromagnetic particles.

6. The heater of claim 1, wherein the lossy heating particles are dispersed throughout at least a portion of the body.

7. The heater of claim 1, wherein the lossy heating particles are evenly distributed throughout all of the body.

8. The heater of claim 1, wherein the induction coil comprises an elongated member having a cylindrical cross-section and a plurality of coils therein.

9. The heater of claim 1, wherein the induction coil comprises an elongated member having a flat cross-section and a plurality of coils therein.

10. The heater of claim 1, wherein the particles are distributed in the body such that all parts of the body are heated to a substantially uniform temperature equal to the Curie temperature by supplying power to the induction coil.

11. The heater of claim 1, wherein the body of electrically non-conductive material is conformable to an uneven surface.

12. The heater of claim 1, wherein the electrically nonconductive material comprises silicone rubber.

13. The heater of claim 1, wherein the electrically nonconductive material comprises plastic, the lossy heating particles comprise ferrite particles dispersed in the plastic, and the plastic with the lossy heating particles dispersed comprises a molded shape around the induction coil.

14. The heater of claim 1, further comprising power means for supplying a constant current to the connection means, the power supply providing high frequency alternating current to the induction coil at a preselected frequency effective for heating the lossy heating particles.

15. The heater of claim 1, wherein the induction coil is located in the middle of the body and the body is slightly larger than the induction coil.

16. The heater of claim 1, wherein the induction coil is located in only one-half of the body at one end of the body.

17. The heater of claim 1, wherein a magnetic field generated by the induction coil initially causes lossy heating particles located closest to the induction coil to reach their Curie point after which lossy heating particles located further from the induction coil are heated by the magnetic field, whereby magnetic flux is concentrated close to the induction coil when the body is cold and as portions of the body closest to the induction coil reach the Curie temperature, permeability drops and the magnetic flux expands outward so as to prevent overheating of a central core part of the body.

18. The heater of claim 1, wherein the body includes two opposed surfaces, the induction coil is a coplanar coil formed of flat ribbon conductor located between the opposed surfaces.

19. The heater of claim 1, wherein the body includes two opposed surfaces, the induction coil including a plurality of coils extending in a helical pattern about a central axis, the coils being located inwardly of the opposed surfaces.

20. A heater of claim 1 wherein the lossy heating particles are present in higher concentration in an area within the body for increased heating in said area.

21. A heater of claim 1 further comprising power means for supplying current to the connection means, the power supply providing high frequency alternating current to the induction coil at a preselected frequency effective for heating the lossy heating particles.

22. A method of manufacturing a self-regulating heater, comprising:

providing a body comprising electrically non-conductive material;

providing an internal induction coil embedded within the body;

providing lossy heating particles dispersed within the body, the lossy heating particles producing heat when subjected to an alternating magnetic field produced by the internal induction coil, the lossy heating particles having a Curie transition temperature approximately equal to an auto-regulation temperature at which the body is heated; and

providing connection means for supplying power to the internal induction coil so that the induction coil can produce an alternating magnetic field of sufficient intensity to cause the lossy heating particles to heat the body to the auto-regulated temperature.

23. The method of claim 22, wherein the lossy heating particles comprise ferrites.

24. The heater of claim 22, wherein the induction coil is embedded within the body by molding the electrically nonconductive material around the induction coil.

25. The heater of claim 22, wherein the lossy heating particles comprise ferromagnetic particles or ferrimagnetic particles.

26. The heater of claim 22, wherein the body includes a cavity therein and the induction coil is inserted in the cavity.

27. The heater of claim 22, wherein the lossy heating particles are evenly distributed throughout all of the body.

28. The heater of claim 22, wherein the induction coil is formed of a flat elongated member to provide a coplanar coil.

29. The heater of claim 22, wherein the electrically non-conductive material comprises silicone rubber.

30. The heater of claim 22, wherein the electrically non-conductive material comprises plastic, the lossy heating particles comprise ferrite particles dispersed in the plastic, and the plastic with the lossy heating particles dispersed therein is molded around the induction coil.

31. The heater of claim 22, wherein the induction coil is provided in the middle of the body and the body is slightly larger than the induction coil.

32. The method of claim 22, further comprising providing power means for supplying current to the connection means, the power supply providing high frequency alternating current to the induction coil at a preselected frequency effective for heating the lossy heating particles.

33. The method of claim 22, further comprising providing power means for supplying a constant current to the connection means, the power supply providing high frequency alternating current to the induction coil at a preselected frequency effective for heating the lossy heating particles.

34. A method of claim 22 comprising providing lossy heating particles in higher concentration in an area within the body for increased heating in said area.