EP0250094A1
Expired / Lapsed
EP
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High power self-regulating heater
Assignee: Metcal Inc
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Filing: 1987-05-19
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Granted: —
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Expires: 2007-05-19
Abstract
Abstract An improved performance ferromagnetic self-regulating heater. Constant alternating current is applied to a layered structure including at least one ferromagnetic layer. One or more layers of non-magnetic material is added to the ferromagnetic layer in such a way that the power factor of the heater is very significantly increased above its value in the absence of at least one of the layers. The alternating current flows through the different layers in varying quantities depending on layer composition, temperature and Curie point of the ferromagnetic layer. The structure generates heat by resistive heating as a function of the power applied. In one embodiment a single layer of non-magnetic, high-resistance material is in intimate electrical and thermal contact with one surface of the ferromagnetic material. Below the effective Curie temperature of the ferromagnetic layer the current is mainly confined in the non-magnetic layer which heats with greater efficiency due to better resistive and impedance characteristics. In a second embodiment a further non-magnetic, low-resistance layer is added to the opposite surface of the ferromagnetic material. Here the majority of the current is switched from the high-resistance to the low-resistance layer as the heater approaches effective Curie. By these means impedance matching circuit losses can be substantially reduced and energy is saved in high power systems based on the power factor.
Inventors
- 👤 Philip S. Carter, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 02:37
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/02; H05B6/10; H05B3/00; H05B3/10; H05B3/12; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/125; Y10T428/12521
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
45 words
An electrically resistive heating element comprising: means for regulating temperature within a given range by intrinsic variation of the resistance of said element within said temperature range, and means for decreasing the effective reactance of said heating element at the upper end of said range.
Claim 2
Dependent Claim
45 words
An electrically resistive heating element comprising: means for regulating temperature within a given range by intrinsic variation of the resistance of said element within said temperature range, and means for decreasing the effective reactance of said heating element at the upper end of said range.
Claim 3
Dependent Claim
43 words
An autoregulating heater comprising: means for autoregulating the maximum heat produced through resistive heating by intrinsic variation of the electrical resistance of said heater, and means for improving the power factor of said autoregulating heater while maintaining a significant degree of resistance variation.
Claim 4
Dependent Claim
43 words
An autoregulating heater comprising: means for autoregulating the maximum heat produced through resistive heating by intrinsic variation of the electrical resistance of said heater, and means for improving the power factor of said autoregulating heater while maintaining a significant degree of resistance variation.
Claim 5
Dependent Claim
55 words
An electrically resistive heating element, comprising: a non-magnetic substrate of high thermal and electrical conductivity, a ferromagnetic layer having a first planar face in intimate thermal and electrical contact with said substrate, and a non-magnetic layer of high electrical resistivity in intimate thermal and electrical contact with an opposite planar face of said ferromagnetic layer.
Claim 6
Dependent Claim
55 words
An electrically resistive heating element, comprising: a non-magnetic substrate of high thermal and electrical conductivity, a ferromagnetic layer having a first planar face in intimate thermal and electrical contact with said substrate, and a non-magnetic layer of high electrical resistivity in intimate thermal and electrical contact with an opposite planar face of said ferromagnetic layer.
Claim 7
Dependent Claim
43 words
The heating element of Claim l or Claim 2, wherein, said heating element is comprised of a first layer including a ferromagnetic material, and a second layer comprised of high resistance non-magnetic material in intimate thermal and electrical contact with said ferromagnetic layer.
Claim 8
Dependent Claim
35 words
The heating element of Claim 4, wherein, the flow of current is substantially confined to said resistive low permeability layer by means of skin effect when the temperature of the heater element is below Curie.
Claim 9
Dependent Claim
40 words
The heating element of Claim 4, wherein, a layer of low resistance material is in intimate thermal and electrical contact with said first layer on the opposite side of said first layer from the side contacted by said outer layer.
Claim 10
Dependent Claim
33 words
The heating element of Claim 6, wherein, at about the effective Curie temperature the majority of the current flowing in said heater switches from said high resistance layer to said low resistance layer.
Claim 11
Dependent Claim
29 words
The heating element of Claim 3, wherein, the flow of current is largely confined to said high resistance layer when said heating element is below its effective Curie temperature.
Claim 12
Dependent Claim
32 words
The heating element of Claim 8, wherein, the ferromagnetic layer effectively switches the flow of current from said high to said low resistance layer as the element reaches its effective Curie temperature.
Claim 13
Dependent Claim
27 words
The heating element of Claim 3, wherein, the thickness of said ferromagnetic layer is between 1/3 and 2/3 of a skin depth at a given operating frequency.
Claim 14
Dependent Claim
21 words
The heating element of Claim 3, wherein, said outer layer has resistivities in the range from 60 microhm-cm to 5,000 microhm-cm.
Claim 15
Dependent Claim
15 words
The heating element of Claim 3, wherein, said outer layer is comprised of electroless nickel.
Claim 16
Dependent Claim
24 words
The heating element of Claim 3, wherein, said outer layer is comprised of one of the variety of high resistivity alloys known as nichrome.
Claim 17
Dependent Claim
17 words
The heating element of Claim 3, wherein, said outer layer is comprised of an organic conductive polymer.
Claim 18
Independent Claim
83 words
The method of maintaining a relatively high power factor in a self-regulating heater comprising the steps of initially confining a large proportion of current in a high electrical resistance layer during the period a layer of magnetic material which is in electrical and thermal contact with the high resistance layer is below its effective Curie temperature and allowing an increasingly large proportion of the current to spread into a lower resistance material as the temperature of the magnetic layer approaches its Curie temperature.
Claim 19
Independent Claim
83 words
The method of maintaining a relatively high power factor in a self-regulating heater comprising the steps of initially confining a large proportion of current in a high electrical resistance layer during the period a layer of magnetic material which is in electrical and thermal contact with the high resistance layer is below its effective Curie temperature and allowing an increasingly large proportion of the current to spread into a lower resistance material as the temperature of the magnetic layer approaches its Curie temperature.
Claim 20
Independent Claim
79 words
The method of maintaining a high power factor in a self-regulating multilayered heating element having low and high resistance non-magnetic layers and a magnetic layer lying between and in electrical contact withsaid layers, the method comprising confining the majority of the current to the high resistance layer below the effective Curie temperature of the magnetic material and switching the majority of the current to the low resistance layer as the effective Curie temperature of the magnetic layer is approached.
Claim 21
Independent Claim
79 words
The method of maintaining a high power factor in a self-regulating multilayered heating element having low and high resistance non-magnetic layers and a magnetic layer lying between and in electrical contact withsaid layers, the method comprising confining the majority of the current to the high resistance layer below the effective Curie temperature of the magnetic material and switching the majority of the current to the low resistance layer as the effective Curie temperature of the magnetic layer is approached.
References Cited (Backward Citations)
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