U.S. patent application number 14/551105 was filed with the patent office on 2016-05-26 for mechanical fastener.
The applicant listed for this patent is GE Aviation Systems LLC. Invention is credited to Michel Engelhardt.
Application Number | 20160146545 14/551105 |
Document ID | / |
Family ID | 55301923 |
Filed Date | 2016-05-26 |
United States Patent
Application |
20160146545 |
Kind Code |
A1 |
Engelhardt; Michel |
May 26, 2016 |
MECHANICAL FASTENER
Abstract
A mechanical fastener includes an elongated body having an outer
surface, and inner surface, a first closed end, and a second closed
end, and a mechanical fastener interface provided on the outer
surface, such that the mechanical fastener transfers heat away from
at least one of the first or second ends.
Inventors: |
Engelhardt; Michel;
(Woodbury, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GE Aviation Systems LLC |
Grand Rapids |
MI |
US |
|
|
Family ID: |
55301923 |
Appl. No.: |
14/551105 |
Filed: |
November 24, 2014 |
Current U.S.
Class: |
165/76 |
Current CPC
Class: |
F28D 15/04 20130101;
F28D 15/0275 20130101; F28F 2215/06 20130101; F28F 2275/20
20130101; H01L 23/427 20130101; F28D 15/046 20130101 |
International
Class: |
F28D 15/02 20060101
F28D015/02 |
Claims
1. A mechanical fastener, comprising an elongated body having an
outer surface, an inner surface defining a fluid reservoir, a first
closed end, and a second closed end; a mechanical fastener
interface provided on the outer surface; and a phase change
material provided within the fluid reservoir; wherein the phase
change material provided within the elongated body functions to
transfer heat away from at least one of the first or second
ends.
2. The mechanical fastener of claim 1 wherein the mechanical
fastener interface is threaded.
3. The mechanical fastener of claim 2 wherein the mechanical
fastener is at least one of a bolt or screw.
4. The mechanical fastener of claim 2 wherein the threaded screw is
configured to be receivably coupled with a corresponding threaded
opening.
5. The mechanical fastener of claim 4 wherein the threaded opening
is complementary to the threaded mechanical fastener interface.
6. The mechanical fastener of claim 2 further comprising a
thermally conductive material on the outer surface of the threaded
mechanical fastener interface.
7. The mechanical fastener of claim 1 further comprising a
thermally conductive material on the outer surface.
8. The mechanical fastener of claim 1 wherein at least a portion of
the inner surface comprises capillary walls to provide for
capillary action along the elongated shape.
9. The mechanical fastener of claim 8 wherein the elongated body
defines a body axis and the capillary walls extend along the body
axis.
10. The mechanical fastener of claim 8 wherein the capillary walls
of the inner surface negate gravitational effects on the phase
change material so that elongated body functions to transfer heat
away from at least one end in any orientation.
11. The mechanical fastener of claim 8 wherein the capillary walls
comprise at least a portion of sidewall pattern comprising at least
one of a semi-circular, a circular, a square, a triangular, or an
elliptical cross section.
12. The mechanical fastener of claim 1 wherein the pressure within
the body is less than the standard atmosphere (1 atm).
13. The mechanical fastener of claim 1 wherein the mechanical
fastener interface is configured to be removably coupled with a
corresponding mechanical interface.
14. The mechanical fastener of claim 1 wherein the cross section of
the elongated body is at least one of circular, square, or
elliptical.
15. The mechanical fastener of claim 1 further comprising a heat
pipe.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 14/460,655, filed Aug. 15, 2014, and is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Heat producing devices, such as printed circuit boards,
often contain heat producing components, such as processors or
voltage regulators, which generate heat in sufficient amounts that
may impact the performance of the device, unless the heat is
removed. A thermal plane may be provided in combination with the
heat producing devices to form an assembly to aid in the removal of
heat, typically by providing additional conductive pathways to
disperse the heat.
BRIEF DESCRIPTION OF THE INVENTION
[0003] In one aspect, a mechanical fastener includes an elongated
body having an outer surface, an inner surface defining a fluid
reservoir, a first closed end, and a second closed end, a
mechanical fastener interface provided on the outer surface, and a
phase change material provided within the fluid reservoir. The
phase change material provided within the elongated body functions
to transfer heat away from at least one of the first or second
ends.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] In the drawings:
[0005] FIG. 1 is a schematic cross-sectional view of a heat
producing device in the form of a printed circuit board assembly in
conductive contact with the heat dissipating assembly according to
one embodiment of the invention.
[0006] FIG. 2 is an exploded cross-sectional view of the heat
dissipating assembly according to one embodiment of the
invention.
[0007] FIG. 3 is a top-down view of a heat pipe, taken along line
III-III of FIG. 2, according to one embodiment of the
invention.
[0008] FIG. 4 is a cross-sectional view of the heat pipe
illustrating the operation of the heat transfer.
[0009] FIG. 5 is a perspective view of the heat dissipating
assembly and piezo cooler device, according to a second embodiment
of the invention.
[0010] FIG. 6 is a top-down view of the heat pipe, taken along line
VI-VI of FIG. 5, according to a second embodiment of the
invention.
[0011] FIG. 7 is a schematic cross-sectional view of a heat
producing device in conductive contact with the heat pipe according
to a third embodiment of the invention.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0012] The embodiments of the present invention are related to a
heat dissipating assembly configured to provide cooling to a heat
producing component. In the embodiment of FIG. 1, a printed circuit
board (PCB) assembly 10 is shown comprising a PCB 12 having at
least one heat producing component 14, such as a microprocessor, or
silicon carbine metal-oxide semiconductor field effect transistor
(MOSFET).
[0013] The PCB assembly 10 is shown proximate to a heat dissipating
assembly 16 having a thermally conductive substrate 18, at least
one thermally conductive cooling fin 20, and a thermally conductive
mechanical fastener having a heat pipe 22. Each of the substrate
18, cooling fin 20, and heat pipe 22 may be machined or
manufactured from a same or dissimilar material having a high
thermal conductivity. Non-limiting examples of materials having a
high thermal conductivity may include aluminum, copper, or various
alloys. For purposes of the invention, the type of material is not
limiting. All things being equal, the higher the thermal
conductivity the better. Lesser thermal conductive will merely
reduce the heat transfer performance.
[0014] At least a portion of the substrate 18 may be in thermally
conductive relationship with the heat producing component 14 such
that heat generated by the heat producing component 14 may be
conducted to the substrate 18. For example, as shown, the substrate
18 may support and/or abut the heat producing component 14.
Additionally, embodiments of the invention may include, for
example, a layer of thermally conductive material, such as a
thermal epoxy, between the substrate 18 and the heat producing
component 14, to provide for increased thermal conductivity between
the heat producing component 14 and the heat dissipating assembly
16.
[0015] The cooling fins 20 are thermally coupled with, and extend
away from, the substrate 18, opposite the PCB assembly 10. The
cooling fin 20 may be configured to provide for removing heat, for
example, by convection, when exposed to a fluid, such as air, gas
coolant, or liquid coolant. Example configurations for removing
heat by convection may include designing the cooling fin 20 having
a geometric cross-sectional shape, such as a square, circle,
triangle, ellipse, etc., to increase surface area for convection to
take place. Additional embodiments of the invention may further
include, for example, a patterned outer surface. As shown,
embodiments of the invention may include a plurality of cooling
fins 20, which may be arranged in an arrayed-type pattern, and
positioned proximate to the heat producing component 14.
[0016] Each cooling fin 20 may further include a conductively
coupled heat pipe 22, configured in an elongated shape, such as a
cylinder, located within the fin 20, and extending along at least a
portion of the fin 20. In this sense, the elongated heat pipe 22
includes a first closed end 24 proximate to, and conductively
coupled, including direct and indirect abutment, to, the substrate
18 and an opposing second closed end 26 being distal from the
substrate 18, along the extended portion of the fin 20. The heat
pipe 22 may further include an inner surface 28 and an outer
surface 29, wherein the inner surface 28 defines a fluid reservoir
30 containing a phase change fluid 32 or material, which may, for
example, change phases from a liquid to a gas.
[0017] The phase change fluid 32 may be selected or configured to
provide for a particular heat of vaporization, or enthalpy of
vaporization, which is the combined internal energy and enthalpy
change required to transform a given quality of a fluid from a
liquid into a gas, at a given pressure. In this sense, the heat of
vaporization of the phase change fluid 32 defines the amount of
heat absorbed by the fluid 32 to change the phase of the fluid 32
from a liquid to a gas, and conversely, how much heat is released
from the fluid 32 when the gas condenses back to a liquid.
Furthermore, embodiments of the invention may include a sealed heat
pipe 22 configuration such that the pressure within the fluid
reservoir 30 may be modified to provide a selected heat of
vaporization.
[0018] The particular phase change fluid 32 or pressure within the
reservoir 30 may be selected based on the expected temperatures to
be encountered during the operation of the heat dissipating
assembly to ensure the phase change will occur. For example, a
non-limiting example of pressure within the reservoir may include a
pressure below one standard atmosphere (1 atm). Non-limiting
examples of phase change fluids 32 that may be utilized include
water, ammonia, methanol, acetone, Freon, or any combination
thereof. Phase change fluids 32 may further be selected based on
their compatibilities or incompatibilities with the heat pipe 22
materials or construction.
[0019] While the illustrated example shows the phase change fluid
32 pooled near the second end 26 of the heat pipe 22, embodiments
of the invention may include a heat pipe 22 configuration with a
relatively small cross-sectional area or diameter, such that
circulation of the fluid 32 occurs without the assistance of, and
sometimes in opposition to or negating, external forces such as
gravity. This type of circulation is known as capillary action, and
may provide for a heat pipe 22 configuration where gravitational
effects on the phase change fluid 32 is negligible. Stated another
way, embodiments of the invention may include a heat pipe 22
configuration wherein the phase change fluid 32 is dispersed over
the entire fluid reservoir 30, as opposed to pooled at one end 24,
26 of the reservoir 30. Another effect of the above-described
capillary action embodiment may include a heat pipe 22
configuration where, due to the dispersing of the phase change
fluid 32, may be configured in any orientation.
[0020] FIG. 2 illustrates an exploded cross-sectional view of the
heat dissipating assembly 16 of FIG. 1. As shown, the heat pipe 22
may be independently constructed and/or configured, and assembled
into the cooling fin 20, for example, through an opening 33 of the
substrate 18, cooling fin 20, and/or heat dissipating assembly 16,
at a later time. In this example, at least a portion of the heat
pipe 22 may include, for example, a mechanical fastener interface
provided on the outer surface 29 of the heat pipe 22, illustrated
as a screw 34 having a threaded exterior surface 36. The cooling
fin 20 may complimentary configured to receive the mechanical
fastener, such as a corresponding threaded inner surface 38, as
shown. In this configuration, the mechanical fastener screw 34 may
be fixedly or removably received within the cooling fin 20, through
the opening 33, during assembly. Non-limiting alternative
configurations of the mechanical fastener interface may include
additional threaded configurations, such as a bolt.
[0021] Embodiments of the heat dissipating assembly 16 may further
include a second substrate portion 40 which may fixedly or
removably provide or restrict access to the heat pipe 22 and/or the
opening 33. The second substrate portion 40 may comprise the same
as, or a different material than, the substrate 18. For example, in
a configuration where the second substrate portion 40 may directly
abut the heat producing component 14, it may be desirable to
configure the second substrate portion 40 as a different material
that better matches the coefficient of thermal expansion of the
heat producing component 14 to ensure a reliable thermal contact
between the component 14 and substrate 18 occurs.
[0022] FIG. 3 illustrates a cross section of the inner surface 28
of the heat pipe 22, according to one embodiment of the invention.
In this example, the inner surface 28 may comprise a patterned
sidewall 42 or capillary wall, shown as semi-circular ridges
radially arranged about the surface 28 that may be sized to provide
for the capillary action of the phase change fluid 32. As explained
above, the interaction of the phase change fluid 32 with the
patterned sidewall 42 creates a capillary action which draws and
stores the fluid 32 along the elongated shape of the heat pipe 22,
ensuring a reliable thermal conductivity between the fluid 32 and
the heat pipe 22.
[0023] Embodiments of the heat pipe 22 may include, for example,
machining the patterned sidewall 42 into the inner surface 28, or
forming the sidewall 42 during casing of the pipe 22. Additional
manufacturing or assembly embodiments of the heat pipe 22 may be
included. While the heat pipe 22 is illustrated having a circular
cross section, embodiments of the invention may include alternative
cross-sectional pipe 22 shapes, such as a square, triangle,
ellipse, etc. Furthermore, additional patterned sidewalls 42 may be
included in embodiments of the invention. The pattern of the
sidewalls 42 may be configured based on the phase change fluid 32
to provide for optimized capillary action, as explained above.
[0024] Alternatively, embodiments of the invention may include, for
example, a screw casing, wherein the heat pipe 22 may be fixed,
such as by adhesive, into the screw casing, which may then be
received by the threaded inner surface 38 of the cooling fin 20. In
another alternative embodiment of the invention, the heat pipe 22
may be integrated or machined directly into the cooling fin 20. In
yet another alternative embodiment of the invention, at least one
of the threaded exterior surface 36 of the heat pipe 22 or threaded
inner surface 38 of the cooling fin 20 may include a thermally
conductive later, such as tape, a coating, or an epoxy, to provide
for increased thermal conductivity or a more reliable thermal
contact.
[0025] FIGS. 2, 3, and 4 illustrate the heat transfer cycle of the
heat pipe 22 and phase change fluid 32. The substrate 18, cooling
fin 20, and heat pipe 22 are each configured in a thermally
conductive relationship with each other such that a heat conduction
path may exist, tri-directionally, between the components 18, 20,
22. Thus, in one exemplary scenario, heat generated by the heat
producing component 14 is conductively transferred to the substrate
18, which may be further conductively transferred to the heat pipe
22 (In FIG. 4, illustrated as arrows 44), for example, via the
first end 24 of the pipe 22, and/or via the substrate 18 to the
cooling fin 20, and from the cooling fin 20 to the pipe 22. The
heat conducted to the heat pipe 22 may then be conductively
transferred to, or absorbed into, the phase change fluid 32, which,
in response to the heat conducted from the substrate 18 and/or
cooling fin 20, changes phases from a liquid to a gas (illustrated
as dotted line 46), absorbing at least a portion of the heat.
[0026] In FIG. 4, the phase change fluid gas 46, may traverse along
at least a portion of the heat pipe 22 and condense (i.e. change
phase back to a liquid) along the inner patterned sidewalls 42 of
the heat pipe 22, releasing the stored portion of the heat
(illustrated as arrows 48) into a wall 42 of the heat pipe 22, or
to the cooling fin 20. The heat may then, for example, be released
to the local ambient air surrounding the cooling fin 20. In this
example, a portion of the elongated heat pipe 22 spaced from the
substrate 18 and heat producing component 14, and/or the extension
of the cooling fin 20 corresponding to, and in a thermal
relationship with, the pipe 22, may be cooler, or at a lower
temperature, than another portion of the pipe 22 and fin 20
proximate to the substrate 18 and component 14. The phase change
fluid liquid, in turn, disperses back toward the heat producing
component 14, along the patterned sidewalls 42 of the inner surface
28, by capillary action (illustrated by arrow 54), ready to absorb
heat.
[0027] In this sense, the substrate 18, heat pipe 22, and cooling
fin 20 are configured such that heat generated by the heat
producing component 14 is absorbed by at least the heat pipe 22,
and consequently, the phase change fluid 32 when vaporizing, and is
carried away, or removed from the heat producing component 14
and/or substrate 18 by the phase change fluid 32 gas, to another
portion of the heat pipe 22, spaced away from the heat producing
component 14. At the another, cooler, portion of the heat pipe 22,
the phase change fluid 32 gas condenses along the patterned
sidewall 42 along the inner surface 28 of the pipe 22, releasing
the heat back into the pipe 22 and consequently, the cooling fin 20
relative to the another portion of the pipe 22. The cooling fin 20
may then further dissipate the heat to the local environment, via
convection, as explained above.
[0028] FIG. 5 illustrates an alternative heat dissipating assembly
116 according to a second embodiment of the invention. The second
embodiment is similar to the first embodiment; therefore, like
parts will be identified with like numerals increased by 100, with
it being understood that the description of the like parts of the
first embodiment applies to the second embodiment, unless otherwise
noted. A difference between the first embodiment and the second
embodiment is that heat pipe 122 of the second embodiment may be
configured having a fixed or removable first end 124, and may be
received directly into the opening 133 of the substrate 118 such
that the first end 124 may abut a heat producing component 14 (not
shown) directly.
[0029] Another difference between the first embodiment and the
second embodiment is that heat dissipating assembly 116 of the
second embodiment may further include a component configured to
generate a fluid movement across the cooling fins 20 to provide
increased convection cooling of the fins 20. In the illustrated
example, a piezo cooler 150 may produce a jet of air (shown as
arrows 152) across the cooling fins 20.
[0030] FIG. 6 illustrates a cross section of the inner surface 128
of the heat pipe 122, according to the second embodiment of the
invention. In this example, the inner surface 128 may comprise an
alternatively patterned sidewall 142, shown having inverse
semi-circular ridges, compared to the patterned sidewall 42 of the
first embodiment, radially arranged about the surface 128.
[0031] FIG. 7 illustrates an alternative heat dissipating assembly
216 according to a third embodiment of the invention. The third
embodiment is similar to the first and second embodiments;
therefore, like parts will be identified with like numerals
increased by 200, with it being understood that the description of
the like parts of the first embodiment applies to the second
embodiment, unless otherwise noted. A difference between the first
two embodiments and the third embodiment is that the heat pipe 222
may be utilized to physically separate the printed circuit board 12
and/or heat producing component 14 from a second portion 254, which
may include a second substrate or a cooling portion, such a cooling
fin. In this sense, the heat pipe 222 may connect a "hot" assembly
(e.g. the printed circuit board 12 and/or heat producing component
14) to a "cool" assembly (e.g. the second portion 254) to hold
components in place, while still providing for heat transfer from
the "hot" assembly to the "cool" assembly, as explained above.
[0032] Additionally, FIG. 7 illustrates a combining form, or layer,
of thermally conductive material, shown as thermal epoxy 256,
between the heat pipe 222 and the second portion 254, as well as
between the second end 26 of the heat pipe 222 and the heat
producing component 14. The thermal epoxy 256 may provide for
increased thermal conductivity or a more reliable thermal contact
between the respective thermal connections. Embodiments of the
invention may further include a component configured to generate a
fluid movement across the heat pipe 222, similar to the fluid
movement across the cooling fins in FIG. 5, to provide increased
convection cooling of the pipe 222.
[0033] Many other possible embodiments and configurations in
addition to that shown in the above figures are contemplated by the
present disclosure. For example, while the above-described examples
of heat producing components 14 may primarily described as types of
electrical components (e.g. resistors, inductors, capacitors, power
regulators, pulse laser control boards, etc.), embodiments of the
invention may be applicable to alternative heat dissipating or
cooling configurations, for example, in dissipating heat from
coolant or oil in a generator, or in dissipating heat from a line
replaceable unit, for example, in an aircraft. Furthermore, while
only a single heat producing component 14 is illustrated,
embodiments of the invention may include pluralities of heat pipes
22 and/or cooling fins 20 to account for additional heat producing
components 14 associated with a single heat dissipation assembly
16. The pluralities of heat pipes 22 and/or cooling fins 20 may be
grouped proximate to the respective heat producing components 14,
or distributed across at least a portion of the substrate 18.
[0034] Furthermore, embodiments of the heat pipe 22 may include
additional configurations wherein the fastener includes or is
integrated with an interface for the fastening of the fastener,
such as a screw head. Additional fastening interfaces may be
included. Additionally, the configuration of the heat dissipating
assembly 16, including, for example, cooling fin 20 size, length,
and height, or heat pipe 22 length and phase change fluid 32
composition, may be selected based on the heat dissipation needs of
a particular application, or to ensure a desired cooling
temperature. For instance, a high heat flux, or transient duration
heat producing component 14 may have different heat dissipating
needs than a heat producing component 14 that generates a steady
state heat flux, and thus may need additional heat dissipating
means. Likewise, a heat producing component 14 of a
line-replaceable unit on an aircraft may have size or height
restrictions for the heat pipe 22 and/or cooling fins 20. In yet
another example, a heat dissipating assembly 16 exposed to liquid
coolant may be configured with a smaller, or shorter heat pipe 22
and/or cooling fins 20, due to improved heat dissipation from the
fins 20 to the liquid coolant.
[0035] In yet another embodiment of the heat dissipating assembly
16, more than one heat pipe 22 may be coupled with a single cooling
fin 20, for example, in a stacked configuration along the extending
direction of the fin 20, to provide for increased heat dissipation.
In even yet another embodiment of the heat dissipating assembly 16,
the cooling fins 20 and/or the heat pipe 22 may further comprise a
coating, such as a lusterless black coating including a mixture of
carbon black particles, configured to remove and/or dissipate
additional heat from at least one of the heat pipe 22 or substrate
18 by radiation. Additionally, the design and placement of the
various components may be rearranged such that a number of
different configurations could be realized.
[0036] The embodiments disclosed herein provide a mechanical
fastener having a heat pipe. One advantage that may be realized in
the above embodiments is that the above described embodiments have
superior weight and size advantages over the conventional type heat
dissipating assemblies having air cooling fins, or assemblies
including, for instance, fans or liquid cooling components, to
provide for cooling capabilities. Furthermore, the heat pipe
provides for reduced weight, compared with a solid pin fin
assembly, and provides for approximately eight times greater
thermal conductivity. The thermal management system of coupling
radiation, convection, and conduction provides for a heat
dissipation assembly that competes with actively-cooled heat
management systems (e.g. with fans, pumped coolant, etc.)
[0037] With the proposed mechanical fastener, a high heat
dissipation can be achieved during transient or steady state heat
conditions without additional heat dissipation elements, thus
increasing the reliability of such heat dissipation assemblies by
reducing the need for additional componentry. In addition to
increased reliability, reducing components directly relates to
reducing weight and volume of the assembly, and is especially
beneficial in space and weight-limiting applications, such as
airborne platforms. Moreover, higher heat producing component
reliability can be achieved even when components do not have high
heat conditions.
[0038] When designing mechanical fasteners and heat dissipation
assemblies, important factors to address are power, size, weight,
and reliability. The above described embodiments have a decreased
number of parts compared to an embodiments having active air or
liquid cooling, making the complete system inherently more
reliable. This results in a lower electrical power, lower weight,
smaller sized, increased performance, and increased reliability
system. The lower number of parts and reduced maintenance will lead
to a lower product costs and lower operating costs. Reduced weight
and size correlate to competitive advantages.
[0039] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *