A thermocouple which may be rolled as a tape until needed and a method of making it are described. Thermoelectrically different metals are applied to a strip of electrically nonconductive material in longitudinally overlapping relationship. Apertures may be provided along the tape in overlapping region at predetermined intervals. An adhesive material is applied to the side of the tape opposite the thermoelectric metals either before or after the thermoelectric metals are deposited. The tape may be cut or torn to form a thermocouple device which is ready for application to a body whose temperature is to be monitored or measured

Thomas, R. D.

English

NASA Technical Reports Server

REPLY TO
ATTN OF: V»Jr
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON, D.C. 20546
THERMOCOUPLE
CSC1 14B N73-24472!
Unclas
TOi KSI/Scientific & Technical Information Division
Attention: Miss Winnie M. Morgan
FROM: GP/Office of Assistant General Counsel for
Patent Matters
SUBJECT: Announcement of NASA-Owned U.S. Patents in STAR
In accordance with the procedures agreed upon by Code GP
and Code KSI, the attached NASA-owned U.S. Patent is being
forwarded for abstracting and announcement in NASA STAR.
The following information is provided:
U.S. patent No. :
Government or
Corporate Employee :_
Supplementary Corporate
Source (if applicable) :.
NASA patent Case No. :
NOTE - If; this patent covers an invention made by a corporate
employee of a NASA Contractor, the following is applicable:
Yes / / No /;</
Pursuant to Section 305(a) of the National Aeronautics and
Space Act, the name of the Administrator of NASA appears on
the first page of the patent; however, the name of the actual
inventor (author) appears at the heading of column No. 1 of
the Specification, following the words "... with respect to
an invention of ..."
Elizabeth A. Carter
Enclosure
Copy of patent cited above
NASA-HQ
https://ntrs.nasa.gov/search.jsp?R=19730015745 2020-03-17T08:28:54+00:00Z
April 24, 1973
Filed Jan. 8, 1971
R. D. THOMAS
THERMOCOUPLE TAPE
3,729,343
2 Sheets-Sheet 1
15
18
FIG. 2
16
FIG. 3
BY
8
INVENTORS
RALPH D. THOMAS
TT
A T T O R N E Y S
April 24, 1973
Filed Jan. 8, 1971
R. D. THOMAS
THERMOCOUPLE TAPE
3,729,343
2 Sheets-Sheet 2
27
11—•
FIG.4
27
14
26
15
FIG. 5
BY
INVENTORS
RALPH D. THOMAS
A T T O R N E Y S
United States Patent Office 3,729,343Patented Apr. 24, 1973
3,729,343
THERMOCOUPLE TAPE
Ralph D. Thomas, Cleveland, Ohio, assignor to the United
States of America as represented by the Administrator
of the National Aeronautics and Space Administration
Filed Jan. 8,1971, Ser. No. 104,885
Int Cl. HOlv 1/04
U.S. Cl. 136—225 6 Claims
ABSTRACT OF THE DISCLOSURE
A thermocouple which may be rolled as a tape until
needed and a method of making same are described.
Thermoelectrically different metals are applied to a strip
of electrically nonconductive material in longitudinally
overlapping relationship. Apertures may be provided
along the tape in the overlapping region at predetermined
intervals. An adhesive material is applied to the side of
the tape opposite the thermoelectric metals either before
or after the thermoelectric metals are deposited. The tape
may be cut or torn to form a thermocouple device which
is ready for application to a body whose temperature is
to be monitored or measured.
ORIGIN OF THE INVENTION
The invention described herein was made by an em-
ployee of the United States Government and may be
manufactured and used by or for the Government of the
United States of America for governmental purposes with-
out the payment of any royalties thereon or therefor.
BACKGROUND OF THE INVENTION
The invention relates to thermocouples and is directed
more particularly to a preformed thermocouple which
may be attached to the body whose temperature is to be
measured.
Basically, a thermocouple comprises a junction or con-
tact area of dissimilar metals across which there develops
a voltage dependent on the temperature of the junction
and the particular metals used. If two such junctions are
connected in series with a voltage measuring device, the
measured voltage will be approximately proportional to
the temperature difference of the two junctions. One junc-
tion may serve as a reference by thermally isolating it
from the other which is attached to a body, the tem-
perature of which is to be measured.
The simplest form of thermocouple comprises a pair of
wires of dissimilar metals twisted together at one end
to form a junction.
Most preformed thermocouples available commerciairy
require welding or soldering assembly techniques which
are generally expensive from the standpoint of labor and
apparatus costs. Thermocouple devices must also be pro-
vided with structure for attaching them to the surface of
the body whose temperature is being measured or mon-
itored. Additionally, lead wires must also be attached
and connected to the junction and, because such leads are
generally of a short, predetermined length, connecting
leads must be attached thereto.
Many thermocouples employ thermoelectrically differ-
ent metals such as platinum, platinum alloys and other
noble metals which are extremely expensive. This greatly
increases the cost of a thermocouple particularly where
the wires must be of relatively great diameter for strength
and to facilitate assembly.
In general, thermocouples of the prior art are deficient
in that the junction or area of contact between the dis-
similar metals is very small and, therefore, prohibits its
use where an average temperature of a relatively large
area is desired. .. • .
5 OBJECT AND SUMMARY OF THE INVENTION
It is an object of the invention to provide a thermo-
couple which is inexpensive and which may be discarded
after use.
It is another object of the invention to provide a ther-
mocouple which may be dispensed in the form of a tape
which may be severed by tearing or cutting to provide a
thermocouple junction as well as the necessary connecting
leads.
Still another object of the invention is to provide a
thermocouple which may be attached to body whose tem-
perature is being monitored or measured without welding,
soldering or gluing.
Yet another object of the invention is to provide a
thermocouple in which the junction area may be as large
15
20
25
30
or as small as desired.
It is yet another object of the invention to provide a
thermocouple which has a very fast response time as com-
pared to prior art thermocouples.
Another object of the invention is to provide a thermo-
couple tape from which any desired size thermocouple
may be prepared as needed.
In summary, the invention provides an adhesive backed
thermocouple tape which is inexpensive, easy to use and
has a very fast response time.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial drawing of a tape made in ac-
cordance with the invention.
35
 FIG. 2 is a pictorial drawing of a thermocouple made
in accordance with the invention.
FIG. 3 is an oblique traverse section of one form of
tape made in accordance with the invention.
FIG. 4 is a pictorial drawing of a thermocouple made
by severing a section of the thermocouple tape embody-
ing the invention.
FIG. 5 is a pictorial drawing of another embodiment
of a thermocouple embodying the invention.
45
 DESCRIPTION OF A PREFERRED EMBODIMENT
• Referring now to FIG. 1 there is shown a thermocouple
tape 10 which is coiled or rolled so that any desired
length is easily dispensable. As shown, a first metal layer
50 11 extends traversley across the tape for more than half
its width as defined by the dashed line 12. The dashed
line 12 is more than % width of the tape from one
edge, the center line of the tape being indicated by dashed
' line 13. A second metal layer 14 is also disposed on the
55 tape and extends more than Vi width of the tape from
the other edge thereby forming an overlapping area 1<5.
The overlapping area 16 forms a thermoelectric junction
which-extends longitudinally along the tape.
FIG. 2 illustrates a length of thermocouple 17 which
00 has been severed from the roll 10 by cutting or tearing.
The thermocouple of FIG. 2, ready for application to
a body whose temperature is to be measured, is prepared
by cutting traversely across the metal layer 11 along line
18 and by-removing a section of the overlapping area
65 16 to form an aperture 19.
The severing and removal steps just described establish
a pair of thermocouple junctions 16a and 16b together
with thermocouple connecting leads 20 and 21. Junctions
3,729,343
16a and 166 may be utilized as hot and cpld junctions,
respectively, as will be understood by those skilled in the
thermocouple art. As will be explained presently, a plu-
rality of longitudinally separated apertures 19 may be
formed in the tape as one of the steps in the process of
making the tape. . 5
The embodiment of the thermocouple tape shown in
FIG. 3 includes a plastic protective layer 22 which is
disposed over -the thermocouple metals 11 and 14. The
electrically nonconductive tape 9 on which the metal layers
11 and 14 are disposed is backed by an adhesive layer 8 10
which allows a thermocouple to be attached to a body ,
without any auxiliary parts and without requiring any
gluing, .welding or the like.
The thermocuple tape embodying the invention may
be made by disposing a first thin layer of metal in a strip ^
on one side and along one edge of electrically non-
conductive, flexible tape, as for example,, vinyl," Mylar
or cellophane tape. A second thin layer of a different
metal is then" disposed on the same side along the other
edge of the tape hi a strip which provides a longitudinally 20
extending, overlapping area 16 with the first metal layer :-
11. The metal layers 11 and 14 are dissimilar metals so
that a difference of potential will be generated between
the metal layers 11 and 14 when heat is applied to the
junction provided by the overlapping area 16. However, 25
certain thermoelectrically different metals have ad- :
vantages when used to form thermocouple junctions as
known to those skilled in the art. Examples of these are
gold vs. cobalt; iron vs. constantan; copper vs. constan-
tan;. Chromel vs. Alumel; platinum vs. platinum plus ^0
rhodium; rhenium vs. tungsten; and rhenium vs. .rhenium
alloys. -
, .The metal layers 11 and 14 may be applied to the
tape by plating, sputtering, vapor deposition .or other
suitable means. The minimum thickness of layers 11 and 35
14 is about 4 microns while the maximum practical
thickness because of mechanical stresses- between
the dissimilar metals is about 0.001 inch. The tape may
be either stationary or moving when the metal layers 11
and 14 are applied thereto. To facilitate removal of a
portion of the • overlapping layer 16 to form a thermo-
couple device, perforations or slits 23 may be provided
along- both edges of the overlapping area by punching or
stamping.
To further simplify the manipulations required to form
a thermocouple device from the tape, apertures 19 as
shown in FIG. 2 may be formed in the overlapping area
16 at Longitudinally separated points along the tape. Each
aperture must be at least equal in width to the width of
the overlapping area 16. The length of the aperture is
dependent on the desired .length of the leads 20, 21 and
on the desired area of junctions 16a, 166. The apertures
19 are preferably formed before the metal layers 11 and
14 are deposited to conserve metals 11 and 14 which
otherwise would be discarded with the portions removed 65
to form the apertures 19.
The thermocouple tape is completed by applying an
adhesive coating to the back surface. For certain ap-
plications where it may be desired to protect the thin
metal layers 11 and 14 from damage, a layer of plastic 60
material may be applied over the metal layers.
FIG. 4 illustrates a thermocouple formed from a por-
tion 9 of the tape 10 of FIG. 1 and like parts are identified
by like numerals. Drops of solder 24, 25 attach leads 26
and 27, respectively, to the respective metal layers 11
and -14. The leads 26 and 27 are connected to a suitable
measuring apparatus 28.' The thermocouple is then pressed
onto the object whose' temperature is being measured.
FIG. 5 illustrates a thermocouple which is similar to -Q
that shown in FIG". 2 and like parts are identified by like
numerals. In. the thermocouple of FIG. 5 the whole junc-
tion area 16 extending from the hot junction 16 at the
one end of the tape to the other end of the tape is re-
moved thereby eliminating cold junction 166. With this 75
50
65
configuration the metal layers 11 and 14 serve as con-
necting leads without severing the metal layer 11 as in
FIG. 2.
The metal layers 11 and 14 are connected via leads
26 and 27 to a measuring apparatus 28. The leads 26 and"
27 are attached to metal layers 11 and 14 by connectors
29 and 30, respectively, which may be terminal posts,
clips or solder. As will be clear to those skilled in the art,
leads 26 and 27 may be selected from metals which will
establish a cold or reference junction at either 29 or
30. For example, if lead 26 is copper and layer 11 is
constantan, connector 29 ,will be a reference junction
provided lead 27 is of the same metal as lead 14.
For some applications, the leads 26 and 27 may be
eliminated by attaching the metal layers 11 and 14 of the
embodiment of FIG. 5 directly to the binding posts of
the measuring instrument.
While a preferred embodiment of the invention has
been described, it will be understood that changes and
modifications to the invention may be made by persons
skilled in the thermocouple art without departing from
the spirit and scope, of the invention as set forth in the
claims appended hereto. For example, the width of one
of the metal layers might be much less than one half the
width of the tape provided that the other layer is of
sufficient width to provide an overlapping area extending
along the tape. Also, the metal strips may be set in towards
the center of the tape rather than being disposed along
respective edges.
What is claimed is:
1. A method of making a thermocouple comprising
the steps of:
disposing a first thin strip of a first thermoelectric metal
along one surface of an electrically nonconductive
tape;
disposing a second thin strip of a second thermoelectric
metal along said one surface of said tape parallel to
and longitudinally overlapping said first thin strip
to form a longitudinal junction of said first and
second thin layers;
forming a plurality of apertures in said overlapping
area at predetermined intervals along said tape, each
of said apertures extending traversely at least the
width of said overlapping area;
severing a length of tape substantially longer than any
one aperture; and
severing one of said metallic strips to thereby form a
pair of leads and a pair of junctions.
2. A method of making a thermocouple comprising
the steps of:
disposing a first thin strip of a first thermoelectric metal
along one surface of an electrically nonconductive
tape;
disposing a second thin strip of a second thermoelectric
metal along said one surface of said tape parallel to
and longitudinally overlapping said first thin strip
to form a longitudinal junction of said first and
second thin layers;
forming a row of perforations along each edge of said
overlapping area;
severing a length of tape; and
removing said longitudinal junction except for a por-
tion at one end of said length of tape whereby said
first and second strips serve as connecting leads.
3. The method of claim 2 and including the steps of:
connecting first and second lead wires to. said first and
second strips, respectively, one of said lead wires
being a different metal from the strip to which it
is connected.
4. The method of claim 3 wherein said lead wires are
both the same metal as one of said strips. ,
5. The method of claim 1 wherein the width of each
of said first and second strips is greater than one-half
the width of said tape to provide a longitudinally extend-
ing, overlapping junction area.
3,729,343
6. The method of claim 1 and including the step of
disposing a protective, electrically nonconductive layer
on said first and second metallic strips.
References Cited
UNITED STATES PATENTS
4/1942 Sparrow et al. 136—2012,278,744
2,916,537 12/1959
3,018,311 1/1962
Reid et al. 136—225
Bagno et al. 136—225
3,099,575 7/1963 Hill 117—227
3,427,209 2/1969 Hager, Jr 136—225
3,535,523 10/1970 Wunderman et al 136—225
CARL D. QUARFORTH, Primary Examiner
E. E. LEHMANN, Assistant Examiner
U.S. Cl. X.R.
29—573; 117—71, 107, 217; 136—201


Thermocouple tape

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