U.S. patent application number 09/765629 was filed with the patent office on 2001-06-07 for soft electrical heater and method of assembly.
Invention is credited to Gurevich, Arthur, Kochman, Arkady.
Application Number | 20010002669 09/765629 |
Document ID | / |
Family ID | 22577307 |
Filed Date | 2001-06-07 |
United States Patent
Application |
20010002669 |
Kind Code |
A1 |
Kochman, Arkady ; et
al. |
June 7, 2001 |
Soft electrical heater and method of assembly
Abstract
A soft heater utilizing metal, carbon or conductive ink coated
threads, embroidered on, laminated between or woven into a
nonconductive substrate to form electrical heating circuits. The
heating element may be manufactured in a form of strip, sheet,
sleeve or strand of threads for incorporation into plurality of
articles. The soft heating element core may contain localized
treatment such as positive temperature coefficient (PTC) material
for temperature self-limiting control. The electrode conductors are
attached to said heating element core which is connected in
parallel or in series. The heating element core is shaped in a
desired pattern. The whole assembly is sealed by at least one
electrically insulated layer which envelopes the strips, sheets,
sleeves, ropes or strands of threads.
Inventors: |
Kochman, Arkady; (Mt.
Prospect, IL) ; Gurevich, Arthur; (Wilmette,
IL) |
Correspondence
Address: |
Liniak, Berenato, Longacre & White
Suite 240
6550 Rock Spring Drive
Bethesda
MD
20817
US
|
Family ID: |
22577307 |
Appl. No.: |
09/765629 |
Filed: |
January 22, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09765629 |
Jan 22, 2001 |
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09160540 |
Sep 25, 1998 |
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09160540 |
Sep 25, 1998 |
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08855595 |
May 13, 1997 |
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5824996 |
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Current U.S.
Class: |
219/545 ;
219/528; 219/549 |
Current CPC
Class: |
H05B 2203/017 20130101;
H05B 2203/013 20130101; H05K 1/038 20130101; H01C 1/148 20130101;
H05B 2203/036 20130101; A41D 13/0051 20130101; H02H 5/043 20130101;
H05B 2203/02 20130101; H01C 7/00 20130101; H05B 2203/026 20130101;
H05B 2203/011 20130101; H05B 2203/005 20130101; H05B 2203/003
20130101; H05B 3/145 20130101; H01C 17/00 20130101; H05B 3/58
20130101; H05B 3/342 20130101; H05B 2203/029 20130101; H05B
2203/004 20130101 |
Class at
Publication: |
219/545 ;
219/528; 219/549 |
International
Class: |
H05B 003/54 |
Claims
1. A soft heater having a durable construction for incorporation
into a plurality of articles, said heater comprising: at least one
continuous electrically conductive strip, comprising metal
containing threads, of a desired length and laid out in
predetermined pattern to fit an area of said heater; at least one
gap between portions of said at least one strip; a conductive means
for introducing an electrical current to said strip; an insulating
means for insulating said electrically conductive strip with at
least one layer of nonconductive means.
2. The soft heater according to claim 1, wherein said metal
containing threads comprise electrically conductive metal coated
synthetic polymer threads.
3. The soft heater according to claim 1, wherein said metal
containing threads comprise electrically conductive metal coated
inorganic threads.
4. The soft heater according to claim 1, wherein said metal
containing threads comprise electrically conductive metal coated
carbon threads.
5. The soft heater according to claim 1, wherein said metal
containing threads comprise electrically conductive metal fiber
containing threads.
6. The soft heater according to claim 1, further including
conditioned local spots for providing redundant circuits and
control of electrical resistance in selected areas of said
conductive strip.
7. The soft heater according to claim 1, further including
localized treatment of the selected areas, comprising a positive
temperature coefficient material for providing temperature self
limiting capabilities to said heater.
8. The soft heater according to claim 6, wherein said conditioned
local spots are the selected areas, comprising electrically
conductive carbon carrying material.
9. The soft heater according to claim 6, wherein said redundant
circuits comprise conductive threads bridging electrical circuits
between conductive threads disposed longitudinally in said
conductive strips.
10. The soft heater according to claim 1 further including a shape
holding means for connecting and holding said portions of said
conductive strip in the predetermined pattern.
11. The soft heater according to claim 1, further including a heat
reflecting layer, placed on at least one side of said soft heater,
and electrically insulated from said conductive strip and said
conductive means.
12. A soft heater having a durable construction for incorporation
into a plurality of articles, said heater comprising: a plurality
of continuous electrically conductive strips, comprising metal
containing threads, of a desired length, laid out in a
predetermined pattern to fit an area of said heater; at least one
gap between said strips; bus conductors, comprising nonmetallic
fibers, for introducing an electrical current to said conductive
strips; an insulating means for insulating said electrically
conductive strips and said bus conductors with at least one layer
of nonconductive means.
13. The soft heater according to claim 12, further including
localized treatment for providing redundant circuits and control of
electrical resistance in selected areas of said conductive
strips.
14. The soft heater according to claim 12, further including
localized treatment spots in selected areas, comprising a positive
temperature coefficient material for providing temperature self
limiting capabilities to said heater.
15. The soft heaters according to claim 12, wherein said metal
containing threads comprise metal coated polymer synthetic
threads.
16. The soft heater according to claim 12, wherein said metal
containing threads comprise metal coated inorganic nonmetallic
threads.
17. The soft heater according to claim 12, wherein said metal
containing threads comprise metal coated carbon threads.
18. A soft heater having a durable construction for incorporation
into a plurality of articles, said heater comprising: a conductive
means for introducing an electrical current to said heater; a soft
heating element core comprising metal coated nonmetallic threads
electrically connected to said conductive means; an insulating
means for insulating said heating element core with at least one
layer of nonconductive means.
19. The soft heater according to claim 18, further including
localized treatment providing redundant circuits and control of
electrical resistance in selected areas of said electrically
conductive heating element core.
20. The soft heater according to claim 18, further including
localized treatment of selected areas, comprising a positive
temperature coefficient material for providing temperature self
limiting capabilities to said heater.
21. The soft heater according to claim 18 further including: at
least two bus conductors, disposed at edges of said heater, at
least one selected area of said heater comprising positive
temperature coefficient material, at least one portion of
electroconductive textile, disposed longitudinally between at least
two of said bus conductors, providing that each one portion of said
positive temperature coefficient material directly connects to not
more than one of said bus conductors.
22. The soft heater according to claim 21, wherein said positive
temperature coefficient material connects to said bus conductors by
embedding said bus conductor in said positive temperature
coefficient material.
23. The soft heater according to claim 18, wherein said conductive
means are thin metal coated threads incorporated into a matrix of
said heating element core to form electrode assembly.
24. The soft heater according to claim 18, further including a heat
reflecting layer, placed on at least one side of said heater, and
electrically insulated from said heating element core and said
conductive means.
25. A soft heater having a durable construction for incorporation
into a plurality of articles, said heater comprising: a conductive
means for introducing an electrical current to said heater; a soft
heating element core, comprising carbon coated nonmetallic
inorganic threads, which are electrically connected to said
conductive means; an insulating means for insulating said heating
element core with at least one layer of nonconductive means
26. The soft heater according to claim 25, further including
localized treatment for providing redundant circuits and control of
electrical resistance in selected areas of said heating element
core.
27. The soft heater according to claim 25, further including
localized treatment of selected areas, comprising a positive
temperature coefficient material for providing temperature self
limiting capabilities to said heater.
28. The soft heater according to claim 25, further including: at
least two bus conductors, running through a length of said heater,
at least one selected area of said heater comprising positive
temperature coefficient material, at least one portion of
electroconductive textile, disposed longitudinally between at least
two of said bus conductors, providing that each one portion of said
positive temperature coefficient material directly connects to not
more than one of said bus conductors.
29. The soft heater according to claim 28, wherein said positive
temperature coefficient material connects to said bus conductors by
embedding said bus conductor in said positive temperature
coefficient material.
30. The soft heater according to claim 25, wherein said conductive
means are thin metal coated threads incorporated into the matrix of
said heating element core to form bus electrode assembly.
31. The soft heater according to claim 25, further including a heat
reflecting layer, placed on at least one side of said heater, and
electrically insulated from said heating element and said
conductive means.
32. A soft heater having a durable construction for incorporation
into a plurality of articles, said heater comprising: a conductive
means for introducing an electrical current to said heater; a soft
heating element core, comprising threads impregnated with
conductive ink, which are electrically connected to said conductive
means; an insulating means for insulating said heating element core
with at least one layer of nonconductive means.
33. A soft heater having a durable construction for incorporation
into a plurality of articles, said heater comprising: electrically
conductive sleeve of continuous cross-section, comprising metal
containing threads; a conductive means for introducing an
electrical current to said sleeve; an insulating means for
insulating said electrically conductive sleeve with at least one
layer of nonconductive means.
34. A soft heater having a durable construction for incorporation
into a plurality of articles, said heater comprising: electrically
conductive sleeve of continuous cross-section, comprising
conductive carbon containing threads; a conductive means for
introducing an electrical current to said conductive sleeve; an
insulating means for insulating said electrically conductive sleeve
with at least one layer of nonconductive means.
35. The soft heater according to claim 34, wherein said carbon
containing threads comprise threads impregnated with carbon
containing conductive ink.
36. The soft heater according to claim 34, wherein said carbon
containing threads comprise carbon coated inorganic threads.
37. The soft heater according to claim 34, further including
localized treatment for providing redundant circuits and control of
electrical resistance in selected areas of said electrically
conductive sleeve.
38. The soft heater according to claim 34, wherein said localized
treatment are selected areas, comprising a positive temperature
coefficient material for providing temperature self limiting
capabilities to said soft heater.
39. The soft heater according to claim 34 further including: at
least two bus conductors, running through the length of said
heater, at least one selected area of said soft heater comprising
positive temperature coefficient material, at least one portion of
said electroconductive sleeve, disposed longitudinally between at
least two of said bus conductors, providing that each one portion
of said positive temperature coefficient material directly connects
to not more than one of said bus conductors.
40. The soft heater according to claim 39, wherein said positive
temperature coefficient material connects to said bus conductors by
embedding said bus conductor in said positive temperature
coefficient material.
41. A soft heating cable having a durable construction for
incorporation into a plurality of articles, said heating cable
comprising: electroconductive metal coated nonmetallic fibers,
incorporated into continuous textile bundle, said bundle is
encapsulated by at least one layer of insulating means, cut into
desired length and electrically terminated by two electrode
connectors.
42. The soft heating cable according to claim 41, wherein said
textile bundle is a rope.
43. The soft heating cable according to claim 41, wherein said
textile bundle is a strand of threads.
44. A soft heater having a durable construction for incorporation
into a plurality of articles, said heater comprising conductive
threads, electrically connected in parallel and disposed between
two exterior and at least one interior bus conductors, said bus
conductors are electrically interconnected in such manner as to
enable electrical operating regimes comprising: energizing of said
heater through exterior bus conductors from power leads with
differing electrical potential, energizing of said heater in such
manner that the adjacent energized bus conductors, including
interior bus conductors, have different electrical potential.
45. A method of controlling localized overheating over a large
electrically heated surface area, comprising a combination of a
thermostat with at least one flexible thermal conductor, disposed
over electrically heated area, providing that said flexible thermal
conductor spreads over the heated area, which is larger than the
area covered by said thermostat.
46. A soft heater having a durable construction for incorporation
into a plurality of articles, said heater comprising electrically
conductive threads embroidered in a pattern of a desired heating
element on a flexible nonconductive nonmetallic substrate.
47. The soft heater according to claim 46, wherein said conductive
threads comprise carbon containing nonmetallic threads.
48. The soft heater according to claim 46, wherein said conductive
threads comprise metal coated nonmetallic threads.
49. The soft heater according to claim 46, wherein said conductive
threads comprise metal fiber containing threads.
50. A flexible heater having a durable construction for
incorporation into a plurality of articles, said heater comprising
at least one section of electrically conductive textile disposed
longitudinally between at least two parallel bus conductors,
provided that at least one of said two bus conductors is
electrically connected to a positive temperature coefficient
material directly connected to at least two parallel bus
conductors.
51. A flexible heater having a durable construction for
incorporation into a plurality of articles, said heater comprising:
a soft heating element, comprising electrically conductive threads,
insulated by at least one layer of nonconductive means, a
conductive means for introducing an electrical current to said
heating element, a heat conserving gel, hermetically pouched by the
nonconductive means and disposed on at least one side of said
insulated heating element.
52. The soft heater according to claim 51, further including a
refrigeration circuit to provide for alternating heating and
cooling cycles.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of Invention
[0002] This invention relates to soft electrical heaters, and
particularly to heating elements, which have a soft and strong
metal or carbon containing electrically conductive core.
[0003] 2. Description of the Prior Art
[0004] Heating elements have extremely wide applications in
household items, construction, industrial processes, etc. Their
physical characteristics, such as thickness, shape, size, strength,
flexibility and other characteristics affect their usability in
various applications.
[0005] Numerous types of thin and flexible heating elements have
been proposed, for example U.S. Pat. No. 4,764,665 to Orban et al.
This patent discloses an electrically heated fabric for use in
gloves, airfoils and aircraft parts. In this patent the fabric is
metallized after being formed in a glove structure, following
weaving or arranging in a non-woven format. Copper bus bars are
utilized for introduction of electrical current to the metallized
textile. Having been made of a solid piece of fabric with
metallized coating, this heating element doesn't allow for
flexibility in selection of desired power density. The metallizing
of the formed heating element results in a loss of significant
economies of scale, only a small number of embodiments can be
achieved, thus severely limiting the potential application of this
invention. The '665 design is also not conducive to tight hermetic
sealing through the heater areas (no gaps inside), which can cause
a short circuit through puncture and admission of liquid into the
body of heating element. This element can't be used with higher
temperatures due to the damage that would be caused to the
polyaramid, polyester or cotton metallized fabric, described in the
invention.
[0006] Another prior art example is U.S. Pat. No. 4,713,531 to
Fennekels et al. Fennekels et al. discloses a sheet textile
structure combined with resistance elements. These resistance
elements comprise metallic fibers or filaments with a denier like
that of natural or synthetic textile fibers, and with overall cross
sectional thickness of 8 to 24 microns. The >531 design suffers
from the following drawbacks: being a sheet product, it is not
conducive to hermetic sealing through the body of the heater (no
gaps inside), only perimeter sealing is possible, which can result
in a short circuit due to puncture and admission of liquid into the
body of the heating element; yarns are very heavy: from 1 to 7
grams per 1 meter of yarn; the use of silver fibers makes these
yarns very expensive; individual conductors have a large cross
sectional thickness, each having a outer sheath of braided textile
or elastomer.
[0007] Another prior art example is U.S. Pat. No. 4,538,054 to de
la Bretoniere. The heating element of de la Bretoniere '054 suffers
from the following drawbacks: its manufacturing is complex
requiring weaving of metal or carbon fibers into non-conductive
fabric in a strictly controlled pattern; the use of the metal wire
can result in breakage due to folding and crushing and it affects
softness, weight and flexibility of the finished heater; it can not
be manufactured in various shapes, only a rectangular shape is
available; only perimeter sealing is possible (no gaps inside),
which can result in a short circuit due to puncture and admission
of a liquid into the body of the heating element; the method of
interweaving of wires and fibers does not result in a strong
heating element, the individual wires can easily shift adversely
affecting the heater durability; the fabric base of the heating
element is flammable and may ignite as a result of a short circuit;
it is not suitable for high temperature applications due to
destruction of the insulating weaving fibers at temperatures
exceeding 120.degree. C.
[0008] U.S. Pat. No. 4,149,066 to Niibe at. al. describes a
sheet-like thin flexible heater made with an electro-conductive
paint on a sheet of fabric. This method has the following
disadvantages: the paint has a cracking potential as a result of
sharp folding, crushing or punching; the element is hermetically
sealed only around its perimeter, therefore lacking adequate wear
and moisture resistance; such an element can't be used with high
temperatures due to destruction of the underlying fabric and
thermal decomposition of the polymerized binder in the paint; the
assembly has 7 layers resulting in loss of flexibility and lack of
softness.
[0009] Another prior art example is U.S. Pat. No. 4,309,596 to
George C. Crowley, describing a flexible self-limiting heating
cable, which comprises two conductor wires separated by a positive
temperature coefficient (PTC) material. Said heating wires are
disposed on strands of nonconductive fibers coated with conductive
carbon. This method has the following disadvantages: (a) the wires
are enveloped and separated by the tough PTC material which
thickens and hardens the heating element (b) the distance between
the wires is very limited, due to a nature of the PTC material
having a high electrical resistance, this prevents manufacturing of
heaters with large heat radiating surface; (c) the heater is
limited only to one predetermined highest temperature level,
therefore, this heating device is unable to bypass said temperature
level when a quick heating at the highest temperature is
needed.
[0010] The present invention seeks to alleviate the drawbacks of
the prior art and describes the fabrication of heating element
comprising metal fiber containing, metal coated, carbon containing
or carbon coated textile threads, which is economical to
manufacture; does not pose environmental hazards; results in a
soft, flexible, strong, thin, and light heating element core,
suitable for even small and complex assemblies, such as hardware. A
significant advantage of the proposed invention is that it provides
for fabrication of heating elements of various shapes and sizes,
with predetermined electrical characteristics; allows for a durable
heater, resistant to kinks and abrasion, and whose electro-physical
properties are unaffected by application of pressure, sharp
folding, small perforations, punctures and crushing.
SUMMARY OF THE INVENTION
[0011] The first objective of the invention is to provide a
significantly safe and reliable heating element which can function
properly after it has been subjected to sharp folding, kinks, small
perforations, punctures or crushing, thereby solving problems
associated with conventional flexible heating metal wires. In order
to achieve the first objective, the electric heating element of the
present invention is comprised of electrically conductive threads
coated with metal, carbon, conductive ink, or their combination
which possess the following characteristics: (a) high strength; (b)
high strength-to-weight ratio; (c) very low coefficient of thermal
expansion; (d) softness. The heating element core described in this
invention is comprised of electrically conductive strips, sleeves,
sheets, ropes, or strands of threads/fibers, which radiate a
controlled heat over the entire heating core surface.
[0012] A second objective of the invention is to provide maximum
flexibility and softness of the heating element. In order to
achieve the second objective, the electric heating element of the
invention contains thin (0.01 to 3.0 mm, but preferably within the
range of 0.05-1.0 mm) threads, which are woven into, embroidered
on, or stranded into continuous or electrically connected strips,
sleeves/pipes, ropes, sheets, or bundles, then arranged and
insulated to have gaps between the electrically conductive media.
It is preferable that all insulation components of the heating
element assembly are thin, soft and flexible materials.
[0013] A third objective of the invention is to provide for the
uniform distribution of heat, without overheating and hot spots,
thereby solving the problem of overinsulation and energy
efficiency. In order to achieve this objective, (a) conductive
threads in the heating elements are separated by non-conductive
fibers yarns or polymers, (b) one side of the heating element may
include a metallic foil or a metallized material to provide uniform
heat distribution and heat reflection. It is also preferable that
the soft heating elements of the invention are made without thick
cushioning insulation, which slows down the heat delivery to the
surface of the heating apparatus.
[0014] A forth objective of the invention is to provide for ease in
the variation of heating power density, thereby solving a problem
of manufacturing various heating devices with different electric
power density requirements. In order to achieve the forth
objective, the conductive threads/yarns in the heating element core
are embroidered on, laminated between or woven into strips, ropes,
sleeves/pipes, sheets, or stranded into bundles with predetermined
width, density (of embroidering or weaving) and thickness. It is
preferable that the strips, sleeves/pipes, sheets, ropes or strands
are made of combination of threads/yarns with different electrical
resistance and/or include electrically nonconductive high strength
polymer or inorganic (such as refractory ceramic or fiberglass)
fibers.
[0015] A fifth objective of the invention is to provide for ease in
manufacturing of the heating element core, thereby eliminating a
problem of impregnation of the whole fabric with stabilizing or
filling materials to enable cutting to a desired pattern. In order
to achieve the fifth objective, all strips, sleeves/pipes, sheets,
ropes and threads are assembled into a desired stable shape prior
to the heating element manufacturing.
[0016] A sixth objective of the invention is to provide a
temperature self-limiting properties to the heating element core if
dictated by the heater design thereby eliminating a need for
thermostats. In order to achieve the sixth objective, the positive
temperature coefficient (PTC) material is utilized in the selected
areas of the heating element core.
[0017] The present invention comprises a heating element containing
soft, strong and light electrically conductive threads/yarns acting
as conducting media. The heating element is also highly resistant
to punctures, cuts, small perforations, sharp folding and crushing.
It can be manufactured in various shapes and sizes, and it can be
designed for a wide range of parameters, such as input voltage,
desired temperature range, desired power density, type of current
(AC and DC) and method of electrical connection (parallel and in
series). A heating element preferably consists of non-conductive
fibers/yarns and electrically conductive metal or carbon containing
threads/yarns woven into, embroidered on, laminated between or
stranded into strips, ropes, sleeves/pipes, sheets or strands of
threads.
[0018] The selected areas of the heating element core may contain
highly conductive metal coated threads to provide redundant
circuits in the heater. The heating element core may include a
positive temperature coefficient (PTC) material to impart
temperature self-limiting properties. The heating element core is
shaped by folding or assembling of said conductive media into a
predetermined pattern. The electrodes are attached to said heating
element core and are electrically connected in parallel or in
series. The soft heating element core is sealed to form an assembly
containing at least one electrically insulating layer which
envelops each strip, rope, sleeve/pipe, sheet or strand of
threads.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 shows a plan view of the heating element core
electrically connected in series according to the preferred
embodiment of the present invention;
[0020] FIG. 2 shows a plan view of the heating element core
connected in parallel, utilizing multi-level power output heating
circuit design and optional local area treatments.
[0021] FIG. 3 shows a plan view of the heating element core,
connected in parallel and consisting of various electroconductive
threads woven into, laminated between or embroidered on an
electrically non-conductive substrate. Optional local area
treatments and positive temperature coefficient (PTC) material may
be utilized in this embodiment.
[0022] FIG. 4 shows a plan view of a temperature sensing device
designed to limit a number of thermostats in a heating element and
to afford a more convenient location for the remaining
thermostats.
[0023] FIG. 5 shows a plan view of a heating element utilizing
conductive textile and positive temperature coefficient (PTC)
material to create a wide, PTC controlled, heating circuit. This
heater offers a combination heating regimes.
[0024] FIG. 6 shows an isometric view of a tooth connector utilized
to attach conductive textile thread, bundle, strand or rope heating
cable to a power lead or another heating cable.
[0025] FIG. 7 shows an isometric view of several embodiments of
heating sleeves, utilizing heating elements.
[0026] FIG. 8 shows a plan view of an infra red glowing embroidered
insignia, designed to be visible through the night vision
devices.
[0027] FIG. 9 shows a plan view of a strip heating element
installed in window blind vanes to heat the surrounding air.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The invention consists of a soft heating element core made
by interconnecting of one or more of the following conductive
threads with non-conductive fibers: metal fiber containing, metal
coated or carbon containing threads/yarns. Said core is assembled
as strips, sleeves, pipes, sheets and ropes. It may also take a
form of a strand of threads. The heating element core may, along
with electrically conducting metal fiber, metal coated and/or
carbon containing threads, contain electrically non-conducting
yarns/fibers in various proportion and/or weaving patterns in order
to augment its electrical resistance.
[0029] For convenience of explanation of the invention, the term
"thread" shall mean stitching thread, knitting thread, weaving
thread, yarn and other structures, composed of individual fibers or
a combination of fibers where each individual fiber has a diameter
small enough to make it as soft, flexible and pliable as a
synthetic polymer fiber, such as polyester or nylon. It shall be
also clearly understood that the term "metal fiber" is not the same
as and is not interchangeable with the term "metal wire", the fiber
being considerably thinner than the wire.
[0030] The heating element core described in this invention may
comprise one of the following threads or their combination:
[0031] 1. Metal coated synthetic polymer threads with similar or
varying electrical characteristics.
[0032] 2. Metal coated inorganic threads (made of ceramic or
fiberglass fibers) with similar or varying electrical
characteristics.
[0033] 3. Carbon coated inorganic threads (made of ceramic or
fiberglass fibers) with similar or varying electrical
characteristics.
[0034] 4. Threads impregnated with conductive ink with similar or
varying electrical characteristics.
[0035] 5. Threads, including metal fibers.
[0036] 6. Threads, as indicated in 1 through 5 above, with addition
of nonconductive polymer synthetic fibers.
[0037] 7. Threads, as indicated in 1 through 5 above, with addition
of nonconductive inorganic, including fiberglass, fibers.
[0038] 8. Threads, as indicated in 1 through 7 above with addition
of carbon/graphite threads.
[0039] The non-conductive material of the heating element core may
be in a form of weaving yarns. In a case of an embroidered heating
element and/or element made by laminating of conductive threads
onto or between at least two layers of insulator, the
non-conductive material may be in a form of woven or non-woven
synthetic polymer or inorganic fibers/textile. The synthetic
polymer may also be in a form of thin thermoplastic sheets, such as
polyvinyl chloride (PVC), silicon rubber, polyethylene,
polypropylene, polyurethane, etc.
[0040] The laminating of the conductive threads to the
non-conductive substrate may be achieved by placing the threads
between at least two layers of non-conductive material and
subsequent thermal fusing of the sandwich assembly. It is also
possible to utilize adhesive to laminate conductive and
nonconductive threads to the insulating sleeve, sheet or strip,
made of textile or thermoplastic.
[0041] The metal coated threads described below in this invention
may comprise soft and highly electrically conductive metals such as
silver, gold, copper, tin, nickel, zinc, their alloys or
multi-layer combination. Such metal coatings may be applied on
carbon/graphite, polymer, fiberglass or ceramic threads by
sputtering, electroplating, electroless deposition or other
appropriate techniques.
[0042] The metal fiber containing threads described in this
invention comprise the following metals or their combination:
tungsten, nickel, chromium, iron. The individual metal fibers
within the threads have small enough thickness to make the threads
as soft and flexible as those made of polymer textile materials,
such as polyester or nylon.
[0043] The term "conductive ink" described below in this invention
shall mean conductive ink, paint or adhesive made of
electroconductive media, such as carbon, graphite or metal
particles/fibers dispersed in a solution of nonconductive organic
stabilizer.
[0044] The term "carbon containing threads" described below in this
invention shall mean carbon/graphite threads or threads coated with
carbon or carbon/graphite containing material.
[0045] The term "conductive textile" described below in this
invention shall mean soft electrically conductive substrate
comprising conductive threads and non-conductive materials such as
woven or non-woven textile or thin thermoplastic.
[0046] FIG. 1 shows an example embodiment of electroconductive
heating element core (1) in a form of a strip, folded so as to form
gaps for subsequent sealing, and patterned as dictated by the
heating element design. The conductive strip of the heating element
core (1) consists of electroconductive threads (2), disposed
longitudinally in a strip so as to be separated by nonconductive
material. Such placement is achieved through weaving, embroidering
or laminating of individual threads between at least two layers of
insulating material.
[0047] Portions of the heating element core (1) may contain
localized treatment in order to augment the electrical properties
of the finished product, such localized treatment is performed by
at least one of the following methods: (a) the use of
electroconductive carbon or graphite carrying material (6); (b) the
use of positive temperature coefficient (PTC) material (7); (c) the
use of highly conductive bridging threads (5) in order to create
redundant electrical circuits.
[0048] In order to control overheating, at least one temperature
control device (12), such as thermostat, is placed within the plane
of the heating element. The bends and folds along the length of the
heating element core may be secured by at least one of the
following shape holding means: (a) sewing with electroconductive
threads, preferably metal coated threads, (b) sewing with
nonconductive threads; (c) stapling; (d) gluing; (e) riveting; (f)
fusing or sealing by breathable or hermetic insulating material
(8).
[0049] The heating element core is energized through a power cord
(3), which is connected to the heating element with metal
electrodes (4). The electrodes are flexible and have a flat shape
with large contact area. It is also preferable to use conductive
textile electrodes comprising copper wires and carbon yarns or
electrodes, embroidered to the ends of the heating element core by
highly conductive threads. The electrodes may be attached to the
ends of the heating element core by sewing, stapling, riveting or
using of a toothed connector.
[0050] In addition to the electrodes, the power cord has the
following attachments: (a) electric plug (11), (b) optional power
control device (10), which may include one, some or all of the
following: AC to DC converter, transformer, power level regulator,
on/off switch.
[0051] Depending on the end use of the heating elements, the
heating element assembly process utilizes the following operations
in any sequence:
[0052] (a) folding and shaping the heating element core into a
predetermined shape,
[0053] (b) attachment or embroidering of the electrodes to the
heating element core,
[0054] (c) attachment of lead wires, optional thermostat(s) and the
power cord to the heating element core,
[0055] (d) lamination of the heating element core with the
insulating material,
[0056] (e) securing the pattern of the heating element assembly by
the shape holding means.
[0057] It is preferable to utilize a heat reflecting layer on one
side of the insulated heating element core if dictated by the
heating element design; such heat reflecting layer may be an
aluminum foil or a metallized polymer, electrically insulated from
the electroconductive heating element components.
[0058] FIG. 2 shows an example of the heating element core (1) in a
form of strips, folded and disposed between the electrical bus
electrodes (9), the strips having a straight run and being attached
to the parallel bus electrodes by stitching, stapling or riveting.
The run of the zigzag, the distance between the peaks, may vary
even in the same heating element, thereby varying the finished
element temperature density as may be dictated by the heating
element design. As a variation of this design, the length of
heating element strip (1) between the bus electrodes may be shaped
in a zigzag or other pattern instead of being straight. This
enables a variation of the heating element resistance without
varying the heating element core material. The heating element can
also consist of separate parallel conductive strips electrically
connected to the bus conductors. All strips in this embodiment are
disposed in such manner as to create gaps between the adjacent
strips in order to provide tight hermetic sealing and/or shape
holding during insulation by the nonconductive material. The strips
are tightly connected with bus conductors (9) by stitching (16),
stapling or riveting.
[0059] A heating element of this design may contain optional
localized treatment in order to augment the electrical properties
of the finished product, such localized treatment may be one of the
following methods: (a) the use of electroconductive carbon or
graphite carrying material, (b) the use of positive temperature
coefficient (PTC) material (7), (c) the use of bridging
electroconductive threads (5), such as metal coated threads, in
order to create redundant electrical circuits.
[0060] A novel method of controlling power output is utilized in
this embodiment. By using the third bus electrode, shown in the
middle, the power output can be varied by a factor of 4, at the
same time, requiring 4 times fewer conductive threads. This
provides a double benefit of a more versatile heater at a lesser
cost. This heater has two working regimes, high power output and
low power output.
[0061] In the low power output regime, the middle bus electrode is
not energized and has no function other than a circuit bridge,
providing redundancy in the path of electrical current. In the high
power output regime, utilizing direct current, when the middle bus
electrode is energized, the outer electrodes are switched to be fed
by one power lead, with polarity, opposite to that of the middle
bus electrode. When alternating current is utilized, polarity does
not matter, however power supply circuit is identical to that of a
direct current circuit-the middle bus electrode is fed by one power
lead and the outer electrodes are fed by another.
[0062] Energizing the middle bus electrode enables the heater
strips to complete the circuits in half the distance, thereby
reducing their resistance by one half. This creates two heating
circuits, each putting twice the power of the single larger heating
circuit. Therefore, the power output from the heating element
increases 4 times. Other numerous variations of this design are
possible, based on the desired function.
[0063] There are examples of prior art where attempts were made to
vary temperature and power output within a single heating element,
U.S. Pat. No. 4,250,397 to Gray at al, U.S. Pat. No. 3,739,142 to
Johns, and U.S. Pat. No. 4,788,417 to Graflind. They all use
layering of heating elements to enable power variability. This
layering creates considerably heavier, less flexible and more
expensive heaters. Additionally, because the temperature between
layers is considerably higher than that felt on the outside of the
heater, a localized overheating may occur, melting an insulating
layer and causing short circuit and fire.
[0064] FIG. 3 shows an example of heater utilizing various
conductive threads (2), such as metal coated synthetic polymer or
inorganic threads, carbon coated inorganic threads, threads
impregnated with conductive ink, and/or other types of conductive
threads woven into, laminated between or embroidered on a
non-conductive substrate (14) in any pattern as may be dictated by
the heating element design. The non-conductive substrate (14) for
embroidering or laminating may be made of woven or non-woven
textile, vinyl sheet, silicon rubber, polyethylene or polyurethane
sheet or any other synthetic material. This example of heating
element contains optional localized treated areas in order to
augment the electrical characteristics of the heater. These
localized treated areas may consist of electrical circuit bridging
threads (5), positive temperature coefficient (PTC) materials (7),
and cut out areas (15). The cut out areas (15) are only one
embodiment of gaps, necessary for sealing and/or fusing the outer
insulation layer(s). The other embodiments of gaps may be areas of
non-conductive material between conductive threads.
[0065] The optional PTC material may be located in the middle of
the heating element between the bus electrode conductors (9), as
shown in FIG. 3, near at least one bus electrode conductor or
combined with at least one of the bus electrode conductors as its
integral component.
[0066] The heater is energized by power cord (3), equipped with
electric power level controller (10) and a plug (11). It is
important to note that embroidering of a heating element circuit
provides for virtually unlimited flexibility of design and is a
novel and unique approach in making of heating elements.
Embroidering on or laminating of the conductive threads between the
nonconductive materials allows to reduce the weight and cost of the
heating element. A FIG. 4 shows a novel temperature sensing device
(13), which senses a localized temperature change and, being highly
thermoconductive, delivers heat to a thermostat (12) from different
heating areas. This enables placement of thermostats in the least
objectionable locations. For example, in the case of a heating pad,
mattress pad or a heating blanket, thermostats may be located at
the power cord attachment location and/or at the edges of an
appliance. Utilizing this device may also reduce the number of
necessary thermostats. The device consists of a highly
thermoconductive strip or threads disposed across the heating
element core and preferably insulated from one side to prevent the
dissipation of heat. One end of the thermoconductive strip or
bundle of threads is attached to or wound around a thermostat so as
to enable its quick activation in case of overheating of the
heating element assembly. The thermoconductive sensor may also be
in a form of a patch placed on top or under a thermostat and having
an area considerably larger than the thermostat.
[0067] FIG. 5 shows a heating element, which utilizes known
positive coefficient (PTC) technology with conductive textile
technology, creating a novel and synergetic effect. It enables
creation of a wide, PTC controlled, heating circuit through
energizing busses (A) and (C), and narrow, PTC controlled, heating
circuit through energizing busses (A) and (B), all in one
heater.
[0068] This embodiment also allows for a heating surface with
temperature limits above those of PTC, when energized through
busses (B) and (C). Numerous combinations or sequence of bus
electrodes (9), PTC material (7) and conductive textile (1) are
possible, depending on the end use requirements.
[0069] FIG. 6 shows an example of embodiment of heating element
core (1) in a form of a thread, bundle of threads, or a rope. The
heating element core, covered by insulating layer (8), is energized
through a power cord, which is connected to the heating element
with pressure connector (4). The tight connection to the heating
cable is achieved through insertion of the tooth connector (17)
into a transverse cut in the heating cable and subsequent tight
squeezing of the pressure connector shell around the tooth
(17).
[0070] This heating element core may also be utilized in a flat
heater by laying it out in a pattern dictated by the heating
element design on a shape holding and/or insulating substrate so as
to form gaps for subsequent sealing by the shape holding/insulating
material.
[0071] FIG. 7 shows example of tubular heating elements intended
for heating of pipes or as heating sleeves for various heating
purposes, including health and industrial applications. FIG. 7(A)
shows a heating sleeve with bus electrodes (4) located at the ends
and the resistance threads (2) connected to the busses in parallel.
Optional circuit bridging threads (5) may be utilized to provide
electrical continuity and continued heating capability in case of
localized damage to a limited number of heating threads (2). This
type of heating element may be utilized when the length and the
power output of a heater are known fixed quantities.
[0072] For the variable length heating elements an embodiment shown
in FIG. 7(B) is more suitable. This embodiment shows a heating
element with bus electrodes (9) placed longitudinally, extending
full length of the heating element. The resistance threads (2) are
connected to the busses in parallel. Optional circuit bridging
threads (5) may be utilized to provide electrical continuity in
case of localized damage to a limited number of heating threads
(2). FIG. 7(C) shows a variation of the heating element shown in
FIG. 7(B) utilizing optional PTC material in order to control
localized overheating and forgo the use of thermostat.
[0073] FIG. 8 shows an embodiment of a heating element utilizing
electroconductive threads (2) to embroider a desired pattern or
design on an electrically non-conductive substrate (8).
[0074] One of the uses for this design is in military and/or law
enforcement, where an identifying insignia can be embroidered on
the personnel closing to enable easy identification in the darkness
while using night vision scopes. Only a small power source (18),
sufficient to generate up to 0.1 Wt/inch.sup.2, will provide
adequate heat to be clearly distinguishable through the night
vision devices.
[0075] FIG. 9 shows an embodiment of a heated window blinds vane.
It utilizes conductive textile strips (1) held in a desired shape
and insulated by fusible interfacing (8). The finished heating
element is then installed into a fabric or plastic window blinds
vane. The conductive strip is connected through power leads (3), to
a power source located in the window blinds track. A similar design
may be utilized in ceiling fan blades in order to heat circulated
air or to provide localized comfort heating in modular office
partitions/dividers
[0076] The proposed soft heating elements may be utilized in a
variety of commercial and industrial heater applications, utilizing
direct or alternating current. The main advantage of the heating
elements is the high reliability, which is provided by the tightly
sealed soft and durable electrically conductive threads.
[0077] The process of manufacturing of the insulated heating
elements can be fully automated, it utilizes commercially available
nontoxic, nonvolatile and inexpensive products. Some designs of the
insulated heating core may be manufactured in rolls or spools with
subsequent cutting to desired sizes and further attachment of
electric power cords and optional power control devices.
[0078] The softness and the low temperature density of the
conductive heating elements of the invention enable its utilization
in novel and unique applications. One of such applications is a
heat/cool pad for therapeutic use. This pad combines a surface
heating element, a heat/cold conserving gel, and a refrigeration
circuit placed inside or close to the gel pouch. This design
enables an alternating heat and cold application with the same
device. The variation of such gel pouch design may include a heat
function only. The uses of such gel containing devices are very
versatile and may include child car seat/carrier heater, food
warmer/cooler, comfort heating and cooling pads, and other
devices.
[0079] Further, the use of electrically conductive metal coated
threads, metal fiber containing threads, carbon coated inorganic
threads, threads impregnated with conductive ink, carbon/graphite
yarns, non-conductive ceramic or polymer fibers in the heating
element has the following additional advantages:
[0080] it enables manufacturing of thin, soft and uniformly heating
devices without utilizing conventional metal heater wires;
[0081] it provides high durability of the heating appliances which
can withstand sharp folding, small perforations, punctures and
compression without decreasing of electrical operational
capabilities;
[0082] it provides high tear and wear resistance owing to: (a) high
strength of the conductive threads and (b) tight enveloping around
all electrically conductive media with strong insulating
materials;
[0083] it provides for manufacturing of corrosion and erosion
resistant heating element owing to: (a) high chemical inertness of
the carbon coated inorganic threads and ceramic yarns, (b) hermetic
polymer insulation of the whole heating element, including
electrode connections and temperature control devices, for
utilization in chemically aggressive industrial or marine
environments;
[0084] it offers versatility of variation of the electrical
conductivity of the heating element core owing to: (a) weaving,
embroidering or stranding of the electrically conductive threads to
the predetermined width and thickness of the strips, sleeves,
sheets, ropes or strands of threads; (b) weaving of the yarns to
the predetermined density or type of weaving; (c) weaving,
embroidering or stranding of the conductive threads having
different electrical conductivity in one unit; (d) weaving,
embroidering or stranding of the conductive threads with
nonconductive ceramic and/or polymer threads or fibers. (e) making
cut outs of different shapes to vary the electrical resistance of
the heating element core.
[0085] it provides for saving of electric power consumption owing
to: (a) installation of heat reflective layer and (b) possibility
of placing the heating element with less cushioning and insulation
closer to the human body or to the heated object;
[0086] it allows for manufacturing of heating element with
electrical connection of electrically conductive strips, ropes,
sheets, sleeves/pipes or strands in parallel or in series;
[0087] it overcomes the problem of overheated spots owing to (a)
high heat radiating surface area of the heating element core, (b)
uniform heat distribution by the heat reflective layer, reducing
the possibility of skin burns or destruction of the insulating
layers;
[0088] it provides for extremely low thermal expansion of the
heating element owing to the nature of the electrically conductive
threads, polymer or nonconductive yarns/fibers. This feature is
extremely important for construction applications
(Example:-concrete) or for multi-layer insulation with different
thermal expansion properties;
[0089] it offers high degree of flexibility and/or softness of the
heating appliances depending on the type and thickness of
insulation; and
[0090] it provides technological simplicity of manufacturing and
assembling of said heating element.
[0091] Further, a combination of the electrically conductive
threads and PTC material allows to: (a) provide temperature
self-limiting properties to the soft heating appliances,
eliminating need for thermostats; (b) increase the distance between
the bus electrodes, decreasing the risk of short circuit between
said bus electrodes; (c) provide larger heat radiating area
resulting in higher efficiency of the heater; (d) provide a barrier
for liquid penetration to the parallel bus conductors in the event
of puncturing the insulated heating element core.
[0092] Further, the proposed heating elements can be utilized in,
but not limited to: (a) electrically heated blankets, pads,
mattresses, spread sheets and carpets; (b) wall, office dividers,
window blind vanes, fan blades, furniture, ceiling and floor
electric heaters; (c) vehicle, scooter, motorcycle, boat and
aircraft seat heaters; (d) electrically heated safety vests,
garments, boots, gloves, hats and scuba diving suits; (e) food
(Example:-pizza) delivery and sleeping bags; (f) refrigerator,
road, roof and aircraft/helicopter wing/blade deicing systems, (g)
pipe line, drum and tank electrical heaters, (h) electrical furnace
igniters, etc. In addition to the heating application, the same
conductive textile heating element core may be utilized for an anti
static protection.
[0093] The aforementioned description comprises different
embodiments which should not be construed as limiting the scope of
the invention but, as merely providing illustrations of some of the
presently preferred embodiments of the invention. Additional
contemplated embodiments include: (a) heating element core may
include yarns made of ceramic fibers, such as alumina, silica,
boria, boron nitride, zirconia, chromia, magnesium, calcia, silicon
carbide or combination thereof; (b) heating element core may
comprise electrically conductive carbon/graphite or metal coated
ceramic fibers, such as alumina, silica, boria, zirconia, chromia,
magnesium, calcia, silicon carbide or combination thereof; (c) the
metal coating can be applied on carbon/graphite threads/yarns; (d)
the conductive carbon coated ceramic may take a form of conductive
carbide coating due to the reaction between the carbon and ceramic
base during high temperature deposition; (e) the heating element
assembly may comprise the conductive strips, ropes, sleeves/pipes,
sheets or threads, having different electrical resistance; (f) the
heating element core may be formed into various patterns such as
serpentine or other desired patterns, including ordinary straight,
coil or "U" shaped forms; (g) the electric power cord can be
directly attached to the conductive heating element core without
the use of electrodes, it is possible to utilize electrically
conductive adhesive, conductive paint, conductive polymer, etc. to
assure good electrical connection; (h) the conductive heating
element core can be electrically insulated by the soft
non-conductive fabrics or polymers by sewing, gluing, fusing,
spraying, etc., forming a soft multi-layer assembly; (i) the
conductive soft heating element core can be electrically insulated
by rigid non-conductive materials like ceramics, concrete, thick
plastic, wood, etc.; (j) the shape holding means can be applied on
any part of the heating element core; (k) the heating element core
may be first insulated by the non-conductive material and then laid
out in a desired pattern.
[0094] While the foregoing invention has been shown and described
with reference to a number of preferred embodiments, it will be
understood by those possessing skill in the art that various
changes and modifications may be made without departing from the
spirit and scope of the invention.
* * * * *