Electrical heater for footwear

• US 5,140,131 A
• Filed: 01/15/1991
• Issued: 08/18/1992
• Est. Priority Date: 01/15/1991
• Status: Expired due to Term

• Current Assignee: Hotronic International Limited
• Original Assignee: Albin Koch
• Inventors: Zorn, Heinz H., Macher, David G.
• Primary Examiner(s): Walberg, Teresa J.
• Application Number:
  US07/641,137
• Time in Patent Office: 581 Days
• Field of Search: 219/211, 219/528, 219/529, 219/549, 219/527
• US Class Current: 219/211
• CPC Class Codes: A43B 3/355 heated by an electric current from an external source, e.g. car batteries
• CPC Class Codes: H05B 2203/017 Manufacturing methods or apparatus for heaters
• CPC Class Codes: H05B 2203/036 Heaters specially adapted for garment heating
• CPC Class Codes: H05B 3/342 heaters used in textiles

Abstract

An electrical heater for footwear which is battery-powered and insertable into the footwear. The electrical heater includes a heatable insole, an electrical conductor, and a battery pack. The heatable insole includes an upper outer fabric layer, a heater insert assembly, and a lower outer rubber layer. The heater insert assembly is very thin and flexible and includes highly heat conductive top and bottom layers with a central layer sandwiched therebetween and having a heat conduction coefficient less than the heat conduction coefficients of the top and bottom layers, therefore acting as a momentary heat dam and storage core. A heating element is coupled to the bottom layer and has a surface area considerably smaller than the surface area of the bottom layer.

Claims

1. An electrical heater assembly for footwear, the combination comprising:

an insert assembly for insertion into footwear and including

a bottom heat conductive and flexible layer,

a central heat conductive and flexible layer engaging and fused to said bottom layer,

a top heat conductive and flexible layer engaging and fused to said central layer, and

an electrical heating element located below and engaging said bottom layer,

said central layer having a heat conductive coefficient less than the heat conduction coefficient of said bottom layer;

a source of electrical energy; and

means, coupled to said source of electrical energy and said heating element, for conducting electrical energy to said electrical heating element.

2. An electrical heater assembly according to claim 1, wherein

said heating element has a surface area smaller than the surface area of said top layer.

3. An electrical heater assembly according to claim 1, wherein

said central layer has a heat conduction coefficient of about 0.20 to about 0.30, and

said bottom layer has a heat conduction coefficient of about 92.

4. An electrical heater assembly according to claim 3, wherein

said top layer has a heat conduction coefficient of about 92.

5. An electrical heater assembly according to claim 1, wherein

said top layer is formed of a metal,

said central layer is formed of fiberglass, and

said bottom layer is formed of a metal.

6. An electrical heater assembly according to claim 1, wherein

said top layer is formed of copper,

said central layer is formed of a plurality of laminations of fiberglass, and

said bottom layer is formed of copper.

7. An electrical heater assembly according to claim 1, wherein

said top layer has a surface area about 2,500 times larger than the surface area of the heatable portion of said heating element.

8. An electrical heater assembly according to claim 1, wherein

said bottom layer has a surface area about 2,500 times larger than the surface area of the heatable portion of said heating element.

9. An electrical heater assembly according to claim 1, wherein

said bottom, central and top layers have a combined thickness of about 0.40 millimeters.

10. An electrical heater assembly according to claim 9, wherein

said insert assembly is substantially circular and has a diameter of about 54 millimeters.

11. An electrical heater assembly according to claim 1, and further comprising

an upper outer layer engaging said top layer, and

a lower outer layer engaging said bottom layer.

12. An electrical heater assembly according to claim 11, wherein

said upper outer layer is formed of fabric, and

said lower outer layer is formed of rubber.

13. An electrical heater assembly, the combination comprising:

a bottom heat conductive and flexible layer;

a central heat conductive and flexible layer engaging and fused to said bottom layer;

a top heat conductive and flexible layer engaging and fused to said central layer; and

an electrical heating element located below and engaging said bottom layer,

said central layer having a heat conductive coefficient less than the heat conductive coefficient of said bottom layer.

14. An electrical heater assembly according to claim 13, wherein

said heating element has a surface area smaller than the surface area of said top layer.

15. An electrical heater assembly according to claim 13, wherein

said central layer has a heat conduction coefficient of about 0.20 to about 0.30, and

said bottom layer has a heat conduction coefficient of about 92.

16. An electrical heater assembly according to claim 15, wherein

said top layer has a heat conduction coefficient of about 92.

17. An electrical heater assembly according to claim 13, wherein

said top layer is formed of a metal,

said central layer is formed of fiberglass, and

said bottom layer is formed of a metal.

18. An electrical heater assembly according to claim 13, wherein

said top layer is formed of copper,

said central layer is formed of a plurality of laminations of fiberglass, and

said bottom layer is formed of copper.

19. An electrical heater assembly according to claim 13, wherein

said top layer has a surface area about 2,500 times larger than the surface area of the heatable portion of said heating element.

20. An electrical heater assembly according to claim 13, wherein

said bottom layer has a surface area about 2,500 times larger than the surface area of the heatable portion of said heating element.

21. An electrical heater assembly according to claim 13, wherein

said bottom, central and top layers have a combined thickness of about 0.40 millimeters.

22. An electrical heater assembly according to claim 13, and further comprising

a first water-resistant coating applied to said top layer, and

a second water-resistant coating applied to said bottom layer.

23. An electrical heater assembly for footwear, the combination comprising:

an insert assembly for insertion into footwear and including

a bottom heat conductive and flexible layer,

a central heat conductive and flexible layer engaging said bottom layer,

a top heat conductive and flexible layer engaging said central layer, and

an electrical heating element located below said bottom layer and engaging only the center of said bottom layer, said electrical heating element having a surface are considerably smaller than the surface area of said top layer,

said central layer having a heat conduction coefficient less than the heat conduction coefficient of said bottom layer;

a source of electrical energy; and

means, coupled to said source of electrical energy and said heating element, for conducting electrical energy to said electrical heating element.

24. An electrical heater assembly, the combination comprising:

a bottom heat conductive and flexible layer;

a central heat conductive and flexible layer engaging said bottom layer;

a top heat conductive and flexible layer engaging said central layer; and

an electrical heating element located below said bottom layer and engaging only the center of said bottom layer, said electrical heating element having a surface area considerably smaller than the surface area of said top layer,

sad central layer having a heat conduction coefficient less than the heat conduction coefficient of said bottom layer.

25. An electrical heater assembly for footwear, the combination comprising:

an insert assembly for insertion into footwear and including

a bottom heat conductive and flexible layer,

a central heat conductive, solid, and flexible layer engaging said bottom layer,

a top heat conductive and flexible layer engaging said central layer, and

an electrical heating element located below and engaging said bottom layer,

said central layer having a heat conduction coefficient less than the heat conduction coefficient of said bottom layer;

a source of electrical energy; and

means, coupled to said source of electrical energy and said heating element, for conducting electrical energy to said electrical heating element.

26. An electrical heater assembly, the combination comprising:

a bottom heat conductive and flexible layer;

a central heat conductive, solid, and flexible layer engaging said bottom layer;

a top heat conductive and flexible layer engaging said central layer; and

an electrical heating element located below and engaging said bottom layer,

said central layer having a heat conduction coefficient less than the heat conduction coefficient of said bottom layer.