Heat sensitive heater wire

• US 4,503,322 A
• Filed: 12/01/1983
• Issued: 03/05/1985
• Est. Priority Date: 11/29/1983
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited 1006 OAZA Kadoma-Shi Osaka Japan
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kishimoto, Yoshio, Hayashi, Takeshi
• Primary Examiner(s): Mayewsky, Volodymyr Y.
• Application Number:
  US06/557,115
• Time in Patent Office: 460 Days
• Field of Search: 219/504, 219/505, 219/528, 219/548, 219/541, 219/549, 219/544, 219/553, 338/22 R, 338/22 SD, 338/214, 156/51, 252/518
• US Class Current: 219/505
• CPC Class Codes: H05B 3/56 Heating cables

Abstract

Disclosed is a heat sensitive heater wire comprising a conductor for a first electrode, an internal function layer, a conductor for a second electrode, an external function layer, a conductor for a third electrode, and an insulating housing which are formed in said order, one of the internal function layer and the external function layer comprising a heat generating layer having a self-temperature controllability, the other comprising a high-molecular temperature sensitive layer or a temperature fuse layer. If this heat sensitive heater wire is used, a surface heating device of high safety free from abnormal overheat and local overheat can be obtained.

Claims

1. A heat sensitive heater wire comprising a conductor for a first electrode, an internal function layer on said first electrode, a conductor for a second electrode on said internal function layer, an external function layer on said second electrode, a conductor for a third electrode on said external function layer, and an insulating housing covering said third electrode, one of said internal function layer and said external function layer comprising a heat generating layer having self-temperature controllability, the other function layer comprising one of a high-molecular temperature sensitive layer and a temperature fuse layer, whereby a heating current may be supplied to said heat generating layer via said second electrode and one of said first and third electrodes, and a temperature control current may be supplied to said other function layer via said second electrode and the other of said first and third electrodes to enable control of local overheating.

2. A heat sensitive heater wire according to claim 1 wherein said heat generating layer comprises a carbon black contained high-molecular composition.

3. A heat sensitive heater wire according to claim 1, wherein said high-molecular temperature sensitive layer comprises a temperature sensitive member which can transduce a change in temperature to a change in impedance.

4. A heat sensitive heater wire according to claim 3, wherein said change in impedance is based on one of a change in ion conductivity, permittivity and electron conductivity.

5. A heat sensitive heater wire according to claim 3, wherein said high-molecular temperature sensitive layer comprises ion conductive polyvinyl chloride or a nylon composition.

6. A heat sensitive heater wire according to claim 1 wherein said temperature fuse layer comprises a crystalline high-molecule having a melting point above a self-control temperature of the heat generating layer.

7. A heat sensitive heater wire according to claim 1 wherein at least one of said high-molecular temperature sensitive layer and said heat generating layer has a temperature fuse property.

8. A heat sensitive heater wire according to claim 1 wherein said conductor for a first electrode is spirally formed on a core thread.

9. A heat sensitive heater wire according to claim 1 wherein said conductor for a first electrode is arranged core-wise on a central axial portion of said internal function layer.

10. A heat sensitive heater wire assembly, comprising:

an inner elongated first electrode means;

an elongated heat generating layer comprising a positive temperature coefficient material surrounding and in electrical and thermal contact with said first electrode means;

an intermediate elongated second electrode means surrounding and in electrical and thermal contact with said heat generating layer;

said first and second electrode means being adapted to supply a heating current to said heat generating layer;

an elongated temperature sensing layer comprising a high molecular weight temperature sensitive material surrounding and in electrical and thermal contact with said second electrode means;

an outer elongated third electrode means surrounding and in electrical and thermal contact with said temperature sensing layer;

said second and third electrode means being adapted to supply a temperature monitoring current to said temperature sensing layer; and

an insulating housing surrounding said third electrode means,

whereby any local temperature increase due to local overheating of said heat generating layer varies any current flowing through said third electrode means which current variation may be employed to control such local overheating.

11. A heat sensitive heater wire assembly, comprising:

an inner elongated first electrode means;

an elongated heat generating layer comprising a positive temperature coefficient material surrounding and in electrical and thermal contact with said first electrode means;

an intermediate elongated second electrode means surrounding and in electrical and thermal contact with said heat generating layer;

said first and second electrode means being adapted to supply a heating current to said heat generating layer;

an elongated thermally fusible layer comprising a thermally fusible material surrounding and in electrical and thermal contact with said second electrode means;

an outer elongated third electrode means surrounding and in electrical and thermal contact with said thermally fusible layer;

said second and third electrode means being adapted to supply a temperature monitoring current to said thermally fusible layer; and

an insulating housing surrounding said third electrode means,

whereby any local temperature increase due to local overheating of said heat generating layer results in fusing of the adjacent portion of said thermally fusible layer and a corresponding substantial change in any current flowing through said third electrode means.