Seat heater

• US 5,111,025 A
• Filed: 12/27/1990
• Issued: 05/05/1992
• Est. Priority Date: 02/09/1990
• Status: Expired due to Fees

• Current Assignee: Tyco Electronics Corporation (TE Connectivity Limited)
• Original Assignee: Raychem Corporation (TE Connectivity Limited)
• Inventors: McMills, Corey J., Barma, Pradeep
• Primary Examiner(s): Walberg, Teresa J.
• Application Number:
  US07/634,935
• Time in Patent Office: 495 Days
• Field of Search: 219/217, 219/528, 219/529, 219/549, 219/552, 219/553
• US Class Current: 219/217
• CPC Class Codes: A47C 7/748 for heating
• CPC Class Codes: H05B 2203/004 using zigzag layout
• CPC Class Codes: H05B 2203/011 Heaters using laterally extending conductive material as connecting means
• CPC Class Codes: H05B 2203/017 Manufacturing methods or apparatus for heaters
• CPC Class Codes: H05B 2203/029 Heaters specially adapted for seat warmers
• CPC Class Codes: H05B 3/146 Conductive polymers, e.g. polyethylene, thermoplastics
• CPC Class Codes: H05B 3/36 heating conductor embedded in insulating material

Abstract

A flexible heater in which a heating element in the form of a tape is wrapped around a support member in the form of a flat sheet. The tape, which exhibits flexibility and toughness, has a composition composed of conductive sintered ultrahigh molecular weight polyethylene. The flexible heater is suitable for heating an upholstered seat, e.g. an automobile seat.

Claims

1. A flexible heater which comprises

(1) a support member which is in the form of a flat sheet;

and

(2) a heating element which is in the form of a tape, which has a ratio of external surface area to polymer volume of at least 20 inch^-1, which is wrapped around the support member, and which comprises

(a) a resistive element which is composed of a conductive polymer which comprises

(i) particles of ultrahigh molecular weight polyethylene having a molecular weight of at least 3 million, which particles have been sintered without completely losing their identity, and

(ii) a particulate conductive filler which is present substantially only at or near the boundaries of the coalesced particles; and

(b) elongate electrodes which are secured to opposite margins of the resistive element and which can be connected to a source of electrical power to cause current to pass through the resistive element.

2. A heater according to claim 1 wherein the conductive filler is carbon black.

3. A heater according to claim 2 wherein the polyethylene has a molecular weight of 4 to 6 million.

4. A heater according to claim 3 wherein the conductive polymer has a resistivity of less than 100 ohm-cm.

5. A heater according to claim 2 wherein the resistive element has a ratio of width to thickness of at least 20.

6. A heater according to claim 5 wherein said ratio is 50 to 200.

7. A heater according to claim 6 wherein the resistive element is 0.005 to 0.05 inch thick and 1.0 to 1.5 inch wide.

8. A heater according to claim 1 wherein the ratio of the total surface area of the heating element to the volume of the tape is 40 to 100 inch^-1.

9. A shaped article which comprises

(1) a resilient foam of a polymeric material, and

(2) at least partially embedded in the foam, a heating element which is in the form of a tape which has a ratio of external surface area to polymer volume of at least 20 inch^-1 and which comprises

(a) a resistive element which is composed of

(i) particles of ultrahigh molecular weight polyethylene having a molecular weight of at least 3 million, which particles have been sintered without completely losing their identity, and

(ii) a particulate conductive filler which is present substantially only at or near the boundaries of the coalesced particles;

and

(b) elongate electrodes which are secured to opposite margins of the resistive element and which can be connected to a source of electrical power to cause current to pass through the resistive element.

10. An upholstered seat which comprises a resilient seat member which is covered by a seat cover, a resilient back member which is covered by a back cover, and a flexible heater which lies between the resilient back member and the back cover, or between the resilient seat member and the seat cover, or both, the flexible heater comprising

(1) a support member which is in the form of a flat sheet;

and

(2) a heating element which is in the form of a tape which has a ratio of external surface area to polymer volume of at least 20 inch^-1, which is wrapped around the support member, and which comprises

(a) a resistive element which is composed of

(i) particles of ultrahigh molecular weight polyethylene having a molecular weight of at least 3 million, which particles have been sintered without completely losing their identity, and

(ii) a particulate conductive filler which is present substantially only at or near the boundaries of the coalesced particles; and

(b) elongate electrodes which are secured to opposite margins of the resistive element and which can be connected to a source of electrical power to cause current to pass through the resistive element.

11. A seat according to claim 10 wherein the heater lies only between the resilient back member and the back cover.

12. A seat according to claim 11 wherein the total surface area of the resistive element is 50 to 100 inch².

13. A seat according to claim 10 wherein the back cover and the seat cover are made of leather.

14. A seat according to claim 10 which is in a wheeled vehicle and wherein the heater is switchably connected to the battery of the vehicle.