U.S. patent application number 12/857965 was filed with the patent office on 2012-02-23 for thermal expansion compensator having an elastic conductive element bonded to two facing surfaces.
This patent application is currently assigned to HAMILTON SUNDSTRAND CORPORATION. Invention is credited to William Determan, Daniel Edward Matejczyk.
Application Number | 20120045948 12/857965 |
Document ID | / |
Family ID | 45592904 |
Filed Date | 2012-02-23 |
United States Patent
Application |
20120045948 |
Kind Code |
A1 |
Determan; William ; et
al. |
February 23, 2012 |
THERMAL EXPANSION COMPENSATOR HAVING AN ELASTIC CONDUCTIVE ELEMENT
BONDED TO TWO FACING SURFACES
Abstract
A thermal expansion compensator is provided and includes a first
electrode structure having a first surface, a second electrode
structure having a second surface facing the first surface and an
elastic element bonded to the first and second surfaces and
including a conductive element by which the first and second
electrode structures electrically and/or thermally communicate, the
conductive element having a length that is not substantially longer
than a distance between the first and second surfaces.
Inventors: |
Determan; William; (Sylmar,
CA) ; Matejczyk; Daniel Edward; (West Hills,
CA) |
Assignee: |
HAMILTON SUNDSTRAND
CORPORATION
Windsor Locks
CT
|
Family ID: |
45592904 |
Appl. No.: |
12/857965 |
Filed: |
August 17, 2010 |
Current U.S.
Class: |
439/840 ;
29/825 |
Current CPC
Class: |
C22C 14/00 20130101;
B23K 35/24 20130101; Y10T 29/49888 20150115; B23K 35/00 20130101;
Y10T 29/49073 20150115; Y10T 29/49117 20150115; Y10T 29/4902
20150115; B23K 35/0261 20130101; Y10T 29/49071 20150115 |
Class at
Publication: |
439/840 ;
29/825 |
International
Class: |
H01R 13/33 20060101
H01R013/33; H01R 43/00 20060101 H01R043/00 |
Goverment Interests
FEDERAL RESEARCH STATEMENT
[0001] This invention was conceived under contract no. 1320783 with
the National Air and Space Administration (NASA) having an
effective date of Mar. 11, 2008 and relating to differential growth
of elements requiring a thermal-mechanical coupler with a low
effective Young's Modulus. This invention is unclassified.
Claims
1. A thermal expansion compensator, comprising: a first electrode
structure having a first surface; a second electrode structure
having a second surface facing the first surface; and an elastic
element bonded to the first and second surfaces and including a
conductive element by which the first and second electrode
structures electrically and/or thermally communicate, the
conductive element having a length that is not substantially longer
than a distance between the first and second surfaces.
2. A thermal expansion compensator, comprising: a first electrode
structure having a first surface; a second electrode structure
having a second surface facing the first surface; and a series of
coils arranged side-by-side and between the first and second
electrode structures with respective portions of each of the coils
metallurgically bonded to corresponding portions of the first and
second surfaces.
3. The thermal expansion compensator according to claim 2, wherein
the coils comprise helical coiling.
4. The thermal expansion compensator according to claim 2, wherein
the coils are separate from one another.
5. The thermal expansion compensator according to claim 2, wherein
the coils comprise wires having relatively small diameters relative
to a distance between the first and second electrode
structures.
6. The thermal expansion compensator according to claim 2, wherein
the first and second electrode structures comprise molybdenum
(Mo).
7. The thermal expansion compensator according to claim 6, wherein
the first and second electrode structures further comprise titanium
(Ti).
8. The thermal expansion compensator according to claim 7, wherein
the coils comprise wiring formed of molybdenum (Mo).
9. A thermal expansion compensator, comprising: a first electrode
structure having a first surface; a second electrode structure
having a second surface facing the first surface; and wiring,
including two or more wire sections, each of which is coiled to
form a coil section having opposing ends corresponding to opposing
wire section ends and sides extending therebetween, each of the
coil sections being disposed sidelong between the first and second
electrode structures with respective portions of each of the coil
section sides metallurgically bonded to corresponding portions of
the first and second surfaces.
10. The thermal expansion compensator according to claim 9, wherein
the coil sections comprise helical coiling.
11. The thermal expansion compensator according to claim 9, wherein
the coil sections are separate from one another.
12. The thermal expansion compensator according to claim 9, wherein
the wire sections have a relatively small diameter relative to a
distance between the first and second electrode structures.
13. The thermal expansion compensator according to claim 9, wherein
the first and second electrode structures comprise molybdenum
(Mo).
14. The thermal expansion compensator according to claim 13,
wherein the first and second electrode structures comprise titanium
(Ti).
15. The thermal expansion compensator according to claim 14,
wherein the wiring comprises molybdenum (Mo).
16. A thermal expansion compensator, comprising: a first electrode
structure having a first surface; a second electrode structure
having a second surface facing the first surface; and wiring,
including two or more wire sections, each of which is coiled to
form a coil section having opposing ends corresponding to opposing
wire section ends and sides extending therebetween, each of the
coil sections being disposed between the first and second electrode
structures such that longitudinal axes thereof are substantially
parallel with respective planes of the first and second surfaces
with respective portions of each of the coil section sides
metallurgically bonded to corresponding portions of the first and
second surfaces.
17-22. (canceled)
Description
BACKGROUND OF THE INVENTION
[0002] The subject matter disclosed herein relates to a high
temperature thermal expansion compensator.
[0003] High-temperature thermoelectric materials are generally
brittle, they have a relatively high Young's Modulus and relatively
low allowable strain. They also exhibit low ultimate tensile
strength. Several classes of thermoelectric materials exist with
different values for their coefficients of thermal expansion. When
thermoelectric materials from two different classes are combined to
form a new thermoelectric couple, then, the difference in their
coefficient of thermal expansions requires that a compensation
device be included within the structural frame of the couple to
prevent buildup of high stress levels in the thermoelectric couple
legs and their potential to fracture.
[0004] The required properties for such a compensator include a
very low effective Young's Modulus, they should allow for high
elastic strain, they should be compatible with the operating
environment and have the capability to demonstrate metallurgical
bonding of the compensator into the thermoelectric couple's
electrodes. There are no known materials, or combination of
materials in the form of gradated structures, which can satisfy all
four criteria for the compensator simultaneously.
BRIEF DESCRIPTION OF THE INVENTION
[0005] According to one aspect of the invention, a thermal
expansion compensator is provided and includes a first electrode
structure having a first surface, a second electrode structure
having a second surface facing the first surface and an elastic
element bonded to the first and second surfaces and including a
conductive element by which the first and second electrode
structures electrically and/or thermally communicate, the
conductive element having a length that is not substantially longer
than a distance between the first and second surfaces.
[0006] According to another aspect of the invention, a thermal
expansion compensator is provided and includes a first electrode
structure having a first surface, a second electrode structure
having a second surface facing the first surface and a series of
coils arranged side-by-side and between the first and second
electrode structures with respective portions of each of the coils
metallurgically bonded to corresponding portions of the first and
second surfaces.
[0007] According to another aspect of the invention, a thermal
expansion compensator is provided and includes a first electrode
structure having a first surface, a second electrode structure
having a second surface facing the first surface and wiring,
including two or more wire sections, each of which is coiled to
form a coil section having opposing ends corresponding to opposing
wire section ends and sides extending therebetween, each of the
coil sections being disposed sidelong between the first and second
electrode structures with respective portions of each of the coil
section sides metallurgically bonded to corresponding portions of
the first and second surfaces.
[0008] According to another aspect of the invention, a thermal
expansion compensator is provided and includes a first electrode
structure having a first surface, a second electrode structure
having a second surface facing the first surface and wiring,
including two or more wire sections, each of which is coiled to
form a coil section having opposing ends corresponding to opposing
wire section ends and sides extending therebetween, each of the
coil sections being disposed between the first and second electrode
structures such that longitudinal axes thereof are substantially
parallel with respective planes of the first and second surfaces
with respective portions of each of the coil section sides
metallurgically bonded to corresponding portions of the first and
second surfaces.
[0009] According to yet another aspect of the invention, a method
of assembling a thermal expansion compensator is provided and
includes disposing coils with pins inserted therein on a first foil
layer disposed on a first electrode, disposing a second foil layer
and then a second electrode on the pins and the coils, loading and
then bonding the coils to the first and second foils layers and the
first and second foil layers to the first and second electrodes to
form an assembly, removing the pins and compressing the assembly in
a direction perpendicular to a longitudinal direction of the coils
to achieve a coil compression.
[0010] These and other advantages and features will become more
apparent from the following description taken in conjunction with
the drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0011] The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0012] FIG. 1 is a side view of a thermal expansion compensator
metallurgically bonded to electrodes;
[0013] FIG. 2 is another side view of the compensator
metallurgically bonded to electrodes; and
[0014] FIG. 3A is an axial view of a first pin inserted into a
coil; and
[0015] FIG. 3B is an axial view of a second pin inserted into the
coil of FIG. 3A having been compressed.
[0016] The detailed description explains embodiments of the
invention, together with advantages and features, by way of example
with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0017] With reference to FIGS. 1 and 2, a thermal expansion
compensator 10 is provided and includes a first electrode structure
11 having a first surface 12, a second electrode structure 13
having a second surface 14 facing the first surface 12 and an
elastic element bonded to the first and second surfaces 12 and 14.
The elastic element includes an electrically and/or thermally
conductive element by which the first and second electrode
structures 11 and 13 electrically and/or thermally communicate with
one another along pathways defined by the electrically and/or
thermally conductive element. The electrically and/or thermally
conductive element has a length that is not substantially longer
than a distance between the first and second surfaces.
[0018] The elastic element may include cushioning resin or epoxy
that is conductive or in which the conductive element is suspended,
memory foam that is conductive or in which the conductive element
is suspended, coils laid on end, coils laid on their sides as
described below, leaf springs or similar types of elastic or
cushioning devices. In any case, the pathways along which the first
and second electrode structures 11 and 13 electrically and/or
thermally communicate have respective lengths that are equal to or
slightly longer than the distance between the first and second
surfaces 12 and 14. That is, if the distance between the first and
second surfaces 12 and 14 is X, the respective lengths of the
pathways may be X to about 2X.
[0019] In accordance with embodiments, the thermal expansion
compensator 10 is provided and includes the first electrode
structure 11 having the first surface 12, the second electrode
structure 13 having the second surface 14, which faces the first
surface 12 and a series of coils 15 arranged side-by-side and
between the first and second electrode structures 11 and 13 with
respective portions 155 of each of the coils 15 metallurgically
bonded to corresponding portions 111 and 133 of the first and
second surfaces 12 and 14.
[0020] The coils 15 may be provided in numbers of two or more and
may be formed of wiring, including two or more wire sections 20,
21, where each wire section 20, 21 is coiled into a coil section
25. The coil section 25 has opposing ends 26, 27 that correspond to
opposing wire section ends 28, 29 and sides 30 extending between
the opposing ends 26, 27. Each of the coil sections 25 may be
disposed sidelong between the first and second electrode structures
11 and 13 such that longitudinal axes, A.sub.L, of the coil
sections 25 are substantially parallel with planes, P.sub.1 and
P.sub.2, of the first and second electrode structures 11 and 13.
With the coil sections 25 disposed in this manner, the respective
portions 155 of for example each of the coil section sides 30 are
metallurgically bonded to the corresponding portions 111, 133 of
the first and second surfaces 12 and 14.
[0021] The coils 15 may include helical coiling with, for example,
85 turns per 0.285'' or about 300 turns per inch. The coils 15 may
be separate from one another, as shown in FIG. 1 or, in some cases,
provided as a continuous serpentine structure whereby the coils 15
include substantially straight portions and, for example, hairpin
sections. In any case, the coils 15 include wires or wiring having
a relatively small diameter relative to a distance between the
first and second electrode structures 11 and 13.
[0022] The first electrode structure 11 includes a base 40 formed
of molybdenum (Mo) and, in some cases, stainless steel or similar
materials. The first electrode 11 further includes a titanium (Ti)
layer 41 at the first surface 12. Like the base, the coils 15 may
be formed of molybdenum. The second electrode structure 13 is
arranged similarly with a molybdenum base 50 and a titanium layer
51. In this way, when the thermal expansion compensator 10 is
assembled, during a bonding process in which the thermal expansion
compensator is loaded and heated to about 760 degrees Celsius for
about 120 minutes, the molybdenum of the respective bases 40, 50
diffusion bonds with the titanium layers 41, 51 of the respective
first and second surfaces 12 and 14. Similarly, the titanium layers
41, 51 of the respective first and second surfaces 12 and 14
diffusion bonds with the molybdenum of the coils 15 at the
respective portions 155. Since the bonding temperature is
relatively low as compared to, for example, the melting
temperatures of components associated with the thermal expansion
compensator 10, damage to those components during the bonding
process can be avoided or substantially reduced.
[0023] The thermal expansion compensator 10 described herein thus
employs a set of, for example, helical coils 15, made from
relatively small diameter wire, which are laid on their sides 30.
These coils 15 are metallurgically bonded into the first and second
electrode structures 11 and 13. Once the bonding is achieved, the
coils 15 act like springs in the orthogonal direction allowing
elastic compression of each wire ring for a relatively low
deflection force. Models of coil diametrical deflection with
applied force can be applied to predict overall force-deflection
behavior and to calculate its effective spring constant. In the
thermal expansion compensator 10, therefore soft compliance (i.e.,
thermal expansion) is possible along with low thermal and
electrical impedance. In particular, a relatively very low
effective Young's Modulus is achieved under relatively high elastic
strain levels of 15% or greater.
[0024] Coil diameter and coil-to-wire outside diameter ratios can
be varied in the design of the thermal expansion compensator 10 to
change the desired elastic deflection range. The number of coils
15, the wire material and its treatment and the number of turns per
inch of coil 15 can be changed to adjust the effective spring
constant. The wire material can be selected or a twisted wire rope
construction can be used for different operating environments and
other uses.
[0025] In accordance with further aspects of the invention, the
thermal expansion compensator 10 is assembled with reference to
FIG. 3A. Initially, the coils 15 are formed and positioned onto
pins 60, such as temporary molybdenum pins, and held with a holder.
The holder, the pins 60 and the coils 15 are then positioned on
temporary foil for subsequent transfer. A layer 41 of titanium foil
(0.0005'' thick) is then placed onto a molybdenum base 40 of the
first (hot) electrode structure 11 and the holder, the pins 60 and
the coils 15 are placed on top of the titanium layer 41. At this
point, positions of the pin 60 and the titanium layer 41 are
verified and a second titanium layer 51 is placed on top of the
coils 15. The base 50 of the second electrode structure 13 is then
placed on the layer 51, a remainder of tooling for applying load is
installed and the structure is transferred to, for example, a
furnace hearth where load application may be prepared.
[0026] The bonding process includes application of a downward load
to the base 50 of the second electrode structure 13 and across the
coils 15 to be bonded. Bonding is then performed at about 760
degrees Celsius for about 120 minutes. Once the bonding is
complete, the pins 60 are removed from the coils 15 under a
microscope as is necessary. Following pin 60 removal, the coils 15
may be optionally compressed using tooling to precisely control a
position of the base 50. Thus, the thermal expansion compensator 10
assembly can be compressed to provide a desired compression of the
coils 15 perpendicular to their longitudinal axes, A.sub.L. This
compression is optional and may be carried out to modify the coil
shape, as shown in FIG. 3B, and thereby to modify the effective
Young's modulus of the assembly.
[0027] With reference to FIG. 3B, a second optional bond cycle may
be employed to provide for additional bonding beyond that which is
achieved in the initial bonding. Here, a second set of pins 70,
such as molybdenum pins or stainless steel pins, are selected and
sized to precisely fit the inner diameter obtained in the coil 15
compression. The second pins 70 are installed and provide support
during a second loading and bonding sequence, which is
substantially similar to the initial sequence.
[0028] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *