A flexible heat transfer apparatus used to flexibly connect and thermally couple a thermoelectric cooler to an object to be cooled is disclosed. The flexible heat transfer apparatus consists of a pair of flexible corrugated sheets made from high thermal conductivity materials such as copper, aluminum, gold, or silver. The ridges of the corrugated sheets are oriented perpendicular to one another and bonded sandwich-fashion between three plates to define an upper section and a lower section. The upper section provides X flexure, the lower section provides Y flexure, and both sections together provide Z flexure

Bard, Steven

Jones, Jack A.

Petrick, S. Walter

English

NASA Technical Reports Server

United States Patent 
Jones et al. 
[54] nEXIBLE THERMAL APPARATUS FOR 
MOUNTING OF THERMOELE-IC 
COOLER 
[75] Inventors: Jack A. Jones, Los Angeles; S. 
Walter Petrick, La Canada; Steven 
Bard, Northridge, all of Calif. 
represented by the Adminisptor of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[73] Assignee: The United States of America as 
[21] Appl. No.: 560,908 
[22] Filed: Jul. 31,1990 
[51] Int. Cl .5  ................................................ F28F 7/00 
[52] U.S. Cl. ........................................ 165/1; 165/185; 
136/204 
[58] Field of Search ..................... 165/80.2, 80.3, 185, 
165/1; 174A6.3; 357/81; 361/386, 388, 389; 
62/3.1, 3.7; 136/200, 203, 204 
[561 References Cited 
U.S. PATENT DOCUMENTS 
3,244,224 4/1966 Hnilicka, Jr. .................. 165/32 HV 
3,332,807 7/1967 Boehmer et al. ................... 136/203 
3,337,309 8/1967 Lewis et al. .................... 136/230 X 
3,412,566 11/1968 Townsend et al. ............. 136/212 X 
3,449,172 6/1969 Dingwall ............................ 165/185 
3,482,198 12/1969 Hopper, Jr. ..................... 361/386 X 
[ill Patent Number: 5,031,689 
[45] Date of Patent: Jul. 16, 1991 
3,804,676 4/1974 Sell, Jr. ............................... 136/205 
3,969,149 7/1976 Thomas et al. ..................... 136/225 
4,273,183 6/1981 Altoz et al. ........................... 165/32 
4,410,756 10/1983 Schwagerman .................... 136/221 
4,465,895 SA984 Verner et al. ....................... 136/225 
4,869,068 9/1989 Van Volten ......................... 62/51.1 
4,873,843 10/1989 Van Volten ......................... 62/51.1 
OTHER PUBLICATIONS 
“Thermoelectric Cooler”, Pesco Products Div. of Bor- 
g-Warnes, Model 094492-010. 
Primary Examiner-Allen J. Flanigan 
Attorney, Agent, or Firm-Thomas H. Jones; Harold W. 
Adams; John R. Manning 
VI ABSTRACT 
A flexible heat transfer apparatus used to flexibly con- 
nect and thermally couple a thermoelectric cooler to an 
object to be cooled. The flexible heat transfer apparatus 
consists of a pair of flexible corrugated sheets made 
from high thermal conductivity materials such as cop- 
per, aluminum, gold, or silver. The ridges of the corru- 
gated sheets are oriented perpendicular to one another 
and bonded sandwich-fashion between three plates to 
define an upper section and a lower section. The upper 
section provides X flexure, the lower section provides 
Y flexure, and both sections together provide Z flexure. 
10 Claims, 1 Drawing Sheet 
32 
40’ 
https://ntrs.nasa.gov/search.jsp?R=19910018071 2020-03-24T07:00:24+00:00Z
US. Patent July 16, 1991 s,o31,6ag 
FIG. 1 
5,03 1,689 
1 2 
being bonded to the sink object; and at least one flexible 
heat conductive means located between said heat con- 
ductive plates, said heat conducting means being flexi- 
ble in at least one direction relative to said heat conduc- 
5 tive plates. In the preferred embodiment, there are three 
heat conductive plates, and the flexible heat conductive 
means is comprised of a pair of orthogonally oriented 
sinusoidally corrugated heat conductive sheets. 
FLEXIBLE THERMAL APPARATUS FOR 
MOUNTING OF THERMOELECTRIC COOLER 
ORIGIN O F  THE INVENTION 
The invention described here. was made in the per- 
fomance of work under a NASA contract, and is sub- 
ject to the provisions of Public Law 96-517 (35 U.S.C. 
Section 202) in which the Contractor has elected not to ,o 
retain title. BRIEF DESCRIPTION O F  THE DRAWINGS 
The just-summarized invention will now be described 
in detail in coniunction with the drawinas of which: TECHNICAL FIELD 
This invention relates generally to flexible heat trans- FIG. 1 is a Grspective view of the preferred flexible 
fer structures and, more specifically, to a flexible ther- heat transfer apparatus according to the present inven- 
mal mounting apparatus for use between a thermoelec- l5 tion as used with a thermoelectric cooler 40 and an 
tric cooler and an object to be cooled. object to be cooled 20. 
BACKGROUND ART DETAILED DESCRIPTION O F  THE 
In a preferred embodiment, the present invention is INVENTION 
intended to be used with thermoelectric coolers *O A preferred flexible heat transfer apparatus 10 ac- 
(TECs). The theory of operation behind TECs is well cording to the present invention is illustrated in FIG. 1. 
known and does not form a material Part of the Present As shown, the flexible heat transfer apparatus 10 is 
invention, and therefore will not be covered in great comprised of a pair of flexible heat conductive means 
detail herein. Suffice it to say that TECS are solid State 12, 14 that are sandwiched or bonded between a plural- 
devices that use the cooling effect caused by applying a 25 ity of heat conductive plates 16, 18, 20. The preferred 
voltage differential across two dissimilar, joined metals. flexible heat conductive 12,14 illustrated in FIG. 
A TEC is generally divided into a top stage and a bot- 1 are comprised of sinusoidally corrugated sheets of 
tom stage. When the top stage is the bottom high heat conduction, thin, flexible foil such as copper, 
stage is heated such that there are net differential expan- aluminum, gold, Or silver. Other types of materials and- 
sions created in the TEC relative to its external sur- 30 /or geometries are, of course, suitable as said flexible 
roundiags. Because TECs are relatively fragile and heat conductive 12, 14. subject to contact with its surroundings so that it is The flexible heat conductive sheets 12, 14 
are bonded between the plurality of heat conductive protected from external loading due to thermal expan- sion and/or externally applied loads. plates 16, 18, 20 so as to define an upper section 15 and In the prior art, such stress protection has been 35 
achieved with very expensive devices known as thermal a lower section 17* A corrugated sheet 12, l4 may be 
straps. The prior art thermal straps are typically fabri- formed by placing consecutive cylindrical pins onto 
cated from expensive, flexible woven silver fabric mate- sides of a flat sheet, bonding the resulting 
rial. These woven silver thermal straps are very expen- corrugated ridges to the heat conductive plates, and 
sive because of the need for complicated assembly fix- 40 then removing the cylindrical pins. In the upper section 
tures, as well as the need for assembly techniques such 15, the ridges Of the first flexible corrugated heat con- 
% custom vacuum e1CtrOn-be.m welding. M ~ ~ ~ ~ ~ ~ ~ ,  ductive sheet 12 are bonded to the underside of the first 
the thermal resistance of the silver thermal heat conductive plate 16 and the top side of the second 
straps is relatively high, typically in the neighborhood heat conductive plate 18. The lower Section 17 iS Simi- 
of 10' C. temperature increase for each watt of heat 45 larly fOrmed by having the ridges of corrugated sheet 
transmitted through the thermal strap. 14 bonded to the underside and top side of heat conduc- 
tive plates 18 and 20, respectively. The upper section 15 
and the lower section 17 are formed such that the ridges STATEMENT OF THE INVENTION 
It is an object of the present invention to provide a or corrugations of the corrugated sheets 12 and 14 are 
flexible thermal transfer apparatus that solves the 50 oriented OflhogonallY with respect to one another. 
above-mentioned problems in the prior art, In this fashion, the upper section 15 can flex left and 
It is a further object of the present invention to pro- right, while the lower section 17 can flex back and 
vide a flexible thermal transfer apparatus that is simple forth. The just-detailed operation of the upper and 
to fabricate and relatively inexpensive to construct; lower sections 15, 17 provides the needed X, Y flexure 
It is a further object of the present invention to pro- 55 components. The Z flexure component is provided by 
vide a flexible thermal transfer apparatus having a rela- the up/down deformation that can occur in the sinusoi- 
tively low thermal resistance characteristic; and dal corrugations of both corrugated sheets 12 and 14. 
It is a further object of the present invention to pro- FIG. 1 further illustrates the intended placement of 
vide a thermal transfer apparatus that is flexible in all the flexible thermal transfer apparatus 10 between a 
three orthogonal directions. 60 thermoelectric cooler 40 and an object to be cooled 22. 
The present invention achieves the above objects by The illustrated thermoelectric cooler 40 is a three-stage 
providing a flexible heat transfer apparatus for conduct- unit. The exact structure of the thermoelectric cooler is, 
ing heat between a source object and a sink object, the however, immaterial to the present invention. The ther- 
apparatus comprising a plurality of heat conductive moelectric cooler 40 is mounted and/or otherwise suit- 
plates being arranged relative to one another such that 65 ably bonded to a heat sink base 30. Thermally insulated 
at least one planar side of each plate is adjacent to at standoffs 32 extend upward from the heat sink base 30 in 
least one planar side of another plate, one of said plates order to substantially support the object to be cooled 
being bonded to the source object and another said plate 22. The standoffs 32 are needed because the flexible 
5,03 1,689 
3 4 
thermal transfer apparatus 10 is not intended to support 
the object to be cooled 22, but rather simply to provide 
a heat transfer path therebetween. 
to the top side of cooler 40, while the 5 wherein flexible corrugated heat-conductive sheets are comprised of a metal selected from the group consisting top side of heat conductive plate 16 is bonded to the of copper, aluminum, gold, and silver. 
underside of the object to be cooled 22. In this fashion, 4. ne flexible heat transfer apparatus of claim 
the flexible thermal transfer apparatus 10 provides an wherein =id 
inexpensive heat transmission strap between the object 5. An apparatus for providing heat transfer between a 
to be cooled 22 and the thermoelectric Cooler 40. The lo thermoelectric cooler and an object to be cooled while 
2. The flexible heat transfer apparatus of claim 1 
wherein said corrugated heat-conductive sheets are 
comprised of sinusoidal corrugations. 
The underside of heat conductive plate 20 is bonded 3. The flexible heat transfer apparatus of claim 1 
object is a thermoelectric cooler. 
apparatus 10 allows for heat transfer, while SimUIta- compensating for vibrations and movement therebe- 
neously providing for flexibility in all three orthogonal tween in all three orthogonal directions, comprising: 
directions. first, second, and third heat-conductive plates ar- 
A thermal heat transfer apparatus according to the ranged in a vertical stack such that at least one 
present invention is particularly desirable because of the planar side of each plate is adjacent to at least one 
high level of thermal conductivity that may be planar side of another plate, said first plate being 
achieved. It is possible to achieve a thermal resistance as bonded to said object to be cooled, said third plate 
being bonded to said thermoelectric cooler, and low as I" C. per watt of heat transmitted. Such high 
said second plate located therebetween; and thermal conductivity makes the device particularly first and second flexible corrugated heat-conductive 
sheets, the ridges of said first flexible corrugated suitable for use with fragile aerospace components, 
sheet being bonded between said first and second because high thermal loads may be transmitted without 
plates in a first orientation and the ridges of said stress load transmission. 
In the preferred embodiment, a thermal resistance of second corrugated sheet being bonded between 
1' C./Watt has been achieved, where heat conductive 25 said second and third plates in a second orientation 
plates 16, 18, 20 are comprised of 1.2-inch thick square that is perpendicular to said first orientation. 
copper Plates, and the CorWPted heat conductive 6. The apparatus of claim 5 wherein said corrugated 
sheets 12 and 14 are comprised of 0.001-inch thick silver heat-conductive sheets are comprised of sinusoidal cor- 
foil that was processed to have 3/32-inch diameter cor- rugations. 
rugations. It is believed that even higher thermal con- 3o 7. The apparatus of claim 5 wherein said corrugated 
ductivity may be achieved by varying the dimensions heat-conductive sheets are comprised of a metal se- 
and/or materials used. lected from the group consisting of copper, aluminum, 
Those skilled in the art will appreciate that various gold, and silver. 
adaptations and modifications of the just-described pre- 8. A method of thermally coupling a thermolectric 
ferred embodiment can be configured without depart- 35 cooler to an object to be cooled comprising the step of 
ing from the scope and of the invention. nere- bonding therebetween a flexible apparatus comprising; 
arranged relative to one another such that at least appended claims, the invention may be practiced other one planar side of each plate is adjacent to at least 
one planar side of another plate, one of said plates than as specifically described herein. 
being bonded to the thermoelectric cooler and 
another of said plates being bonded to the object to 
be cooled; and 
at least one flexible heat conductive means located 
between said heat conductive plates, said heat con- 
ducting means being flexible in at least one direc- 
tion relative to said heat conductive plates; 
the number of said plurality of heat conductive plates 
is three, the first plate being bonded to said object 
to be cooled, the third plate being bonded to said 
thermoelectric cooler, and the second plate being 
located therebetween; and 
the number of said flexible heat conductive means is 
two, said flexible heat conductive means being 
comprised of first and second flexible corrugated 
heat-conductive sheets, the ridges of the first flexi- 
ble corrugated sheet being bonded between thje 
first and second plates in a first orientation and the 
ridges of the second corrugated sheet being bonded 
between the second and third plates in a second 
orientation that is perpendicular to said first orien- 
tation. 
20 
fore, it is to be understood that, within the scope of the a plurality of heat conductive plates, said plates being 
40 We claim: 
1. A flexible heat transfer apparatus for conducting 
heat between a source object and a sink object compris- 
ing: 
a plurality of heat conductive plates, said plates being 
arranged relative to one another such that at least 45 
one planar side of each plate is adjacent to at least 
one planar side of another plate, one of said plates 
being bonded to the source object and another of 
said plates being bonded to the sink object; and 
at least one flexible heat conductive means located 50 
between said heat conductive plates, said heat con- 
ducting means being flexible in at least one direc- 
tion relative to said heat conductive plates, 
wherein the number of said plurality of heat conduc- 
tive plates is three, the first plate being bonded to 55 
said source object, the third plate being bonded to 
said sink object, and the second plate being located 
therebetween; and 
wherein the number of said flexible heat conductive 
means is two, said flexible heat conductive means 60 
being comprised Of first and second corn- 
gated heat-conductive sheets, the ridges ofthe first 
9. The method of claim 8 wherein said corrugated 
heat-conductive sheets are comprised of sinusoidal cor- 
flexible corrugated sheet being bonded between rugations. 
the first and second plates in a first orientation and 10. The method of claim 8 wherein said flexible cor- 
the ridges of the Sec?nd corrugated Sheet being 65 rugated heat-conductive sheets are comprised of a metal 
bonded between the second and third plates in a selected from the group consisting of copper, alumi- 
second orientation that is perpendicular to said first num, gold, and silver, 
orientation. * * * + *  


Flexible thermal apparatus for mounting of thermoelectric cooler

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