U.S. patent application number 14/678438 was filed with the patent office on 2016-10-06 for electronic device including an externally-mounted heat pipe.
The applicant listed for this patent is MOTOROLA SOLUTIONS, INC.. Invention is credited to Jody Akens, Peter Gilmore, George Mtchedlishvili, Avraham Yeini.
Application Number | 20160295679 14/678438 |
Document ID | / |
Family ID | 55745803 |
Filed Date | 2016-10-06 |
United States Patent
Application |
20160295679 |
Kind Code |
A1 |
Yeini; Avraham ; et
al. |
October 6, 2016 |
ELECTRONIC DEVICE INCLUDING AN EXTERNALLY-MOUNTED HEAT PIPE
Abstract
An electronic device including a housing having a container and
a cover. The cover has an opening. The electronic device also
includes a circuit board positioned within the container. The
circuit board includes an electrical component that is aligned with
the opening. The electronic device further includes a heat pipe
mounted to the cover. A portion of the heat pipe extends into the
opening of the cover to thermally communicate with the electrical
component.
Inventors: |
Yeini; Avraham; (Coral
Springs, FL) ; Akens; Jody; (Weston, FL) ;
Gilmore; Peter; (Plantation, FL) ; Mtchedlishvili;
George; (Hallandale Beach, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MOTOROLA SOLUTIONS, INC. |
Schaumburg |
IL |
US |
|
|
Family ID: |
55745803 |
Appl. No.: |
14/678438 |
Filed: |
April 3, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 5/061 20130101;
H05K 1/0203 20130101; H05K 2201/064 20130101; H01L 23/427 20130101;
H05K 1/18 20130101; H05K 9/0022 20130101; H05K 7/20336
20130101 |
International
Class: |
H05K 1/02 20060101
H05K001/02; H05K 5/06 20060101 H05K005/06; H05K 9/00 20060101
H05K009/00; H05K 1/18 20060101 H05K001/18 |
Claims
1. An electronic device comprising: a housing including a container
and a cover, the cover has an opening; a circuit board positioned
within the container, the circuit board including an electrical
component that is aligned with the opening in the cover; and a heat
pipe mounted to the cover, a portion of the heat pipe extending
into the opening of the cover to thermally communicate with the
electrical component.
2. The electronic device of claim 1, wherein the portion of the
heat pipe directly contacts the electrical component.
3. The electronic device of claim 1, wherein the cover includes an
inner surface that faces the circuit board and an outer surface
that is opposite the inner surface, wherein the heat pipe extends
along the outer surface.
4. The electronic device of claim 3, wherein the cover includes a
groove formed in the outer surface, and wherein the heat pipe is
positioned within the groove.
5. The electronic device of claim 4, wherein the opening extends
through the inner surface of the cover and communicates with the
groove.
6. The electronic device of claim 4, wherein the heat pipe is
secured within the groove.
7. The electronic device of claim 4, further comprising a sealing
member positioned at least partially within the groove, wherein the
sealing member encloses the heat pipe within the groove.
8. The electronic device of claim 7, wherein the sealing member
includes thermal epoxy.
9. The electronic device of claim 1, wherein the housing is
hermetically-sealed.
10. The electronic device of claim 9, further comprising a gasket
positioned between the container and the cover.
11. The electronic device of claim 1, further comprising an
electromagnetic interference shield positioned within the housing,
wherein the electromagnetic interference shield separates the
electrical component from other components of the circuit
board.
12. The electronic device of claim 11, wherein the cover includes
an inner surface that faces the circuit board, and wherein the
electromagnetic interference shield includes a track coupled to the
inner surface of the cover.
13. The electronic device of claim 12, wherein the opening is
positioned within a perimeter defined by the track.
14. The electronic device of claim 1, wherein the cover is composed
of metal and includes a plurality of heat-dissipating fins.
15. An electronic device comprising: a sealed housing including a
container and a cover, the cover having an inner surface and an
outer surface, the cover has a groove in the outer surface and an
opening in communication with the groove, the opening extending
through the inner surface of the cover; a circuit board positioned
within the container, the circuit board including an electrical
component that is aligned with the opening in the cover; an
electromagnetic interference shield positioned within the sealed
housing, the electromagnetic interference shield separating the
electrical component from other components of the circuit board;
and a heat pipe positioned within the groove in the cover, a
portion of the heat pipe extending into the opening of the cover
and directly contacting the electrical component to thermally
communicate with the electrical component.
16. The electronic device of claim 15, wherein the heat pipe is
secured within the groove.
17. The electronic device of claim 15, further comprising a sealing
member positioned at least partially within the groove, wherein the
sealing member encloses the heat pipe within the groove.
18. The electronic device of claim 17, wherein the sealing member
includes thermal epoxy.
19. The electronic device of claim 15, further comprising a gasket
positioned between the container and the cover.
20. The electronic device of claim 15, wherein the electromagnetic
interference shield includes a track coupled to an inner surface of
the cover, and wherein the opening is positioned within a perimeter
defined by the track.
Description
BACKGROUND OF THE INVENTION
[0001] Thermal management is a common electromechanical challenge
for electronic devices that include heat-generating circuitry. In
some instances, heat pipes are used to transfer heat from one
location to another location. Heat pipes, however, take up a
relatively large amount of space and may interfere with internal
components of the devices.
[0002] Accordingly, there is a need for an improved mechanism for
managing heat in electronic devices.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0003] The accompanying figures, where like reference numerals
refer to identical or functionally similar elements throughout the
separate views, together with the detailed description below, are
incorporated in and form part of the specification, and serve to
further illustrate embodiments of concepts that include the claimed
invention, and explain various principles and advantages of those
embodiments.
[0004] FIG. 1 is a perspective view of an electronic device
including a heat pipe in accordance with some embodiments.
[0005] FIG. 2 is an exploded perspective view of the electronic
device.
[0006] FIG. 3 is a plan view of an outer surface of a cover of the
electronic device.
[0007] FIG. 4 is a plan view of an inner surface of the cover of
the electronic device.
[0008] FIG. 5 is a cross-sectional view of the electronic device
taken along section line 5-5 of FIG. 1.
[0009] Skilled artisans will appreciate that elements in the
figures are illustrated for simplicity and clarity and have not
necessarily been drawn to scale. For example, the dimensions of
some of the elements in the figures may be exaggerated relative to
other elements to help to improve understanding of embodiments of
the present invention.
[0010] The apparatus and method components have been represented
where appropriate by conventional symbols in the drawings, showing
only those specific details that are pertinent to understanding the
embodiments of the present invention so as not to obscure the
disclosure with details that will be readily apparent to those of
ordinary skill in the art having the benefit of the description
herein.
DETAILED DESCRIPTION OF THE INVENTION
[0011] In one embodiment, the invention provides, an electronic
device that comprises a housing including a container and a cover.
The cover has an opening. The electronic device also comprises a
circuit board positioned within the container. The circuit board
includes an electrical component that is aligned with the opening
in the cover. The electronic device further comprises a heat pipe
mounted to the cover. A portion of the heat pipe extends into the
opening of the cover to thermally communicate with the electrical
component
[0012] In another embodiment, the invention provides an electronic
device comprising a sealed housing including a container and a
cover. The cover has an inner surface and an outer surface. The
cover also has a groove in the outer surface and an opening in
communication with the groove. The opening extends through the
inner surface of the cover. A circuit board is positioned within
the container. The circuit board includes an electrical component
that is aligned with the opening in the cover. An electromagnetic
interference shield is positioned within the sealed housing. The
electromagnetic interference shield separates the electrical
component from other components of the circuit board. A heat pipe
is positioned within the groove in the cover, and a portion of the
heat pipe extends into the opening of the cover and directly
contacts the electrical component to thermally communicate with the
electrical component.
[0013] FIGS. 1 and 2 illustrate an electronic device 10. In the
illustrated embodiment, the electronic device 10 is a two-way radio
that is mountable in a vehicle. In other embodiments, the
electronic device 10 may be, for example, a portable handheld
radio, a laptop computer, a tablet computer, a pager, a smartphone,
or other electronic device or electrical device in which thermal
management is desired to help ensure proper performance of
electronic or other electrical components.
[0014] The illustrated electronic device 10 includes a housing 14,
a circuit board 18, and a heat pipe 22. The housing 14 is generally
made of thermally conductive materials, such as, for example,
metal, that also offer desired electrical properties. The housing
14 includes a container 26 and a cover 30. The container 26 has a
base 34 and sidewalls 38 that define a volume for receiving the
circuit board 18. The container 26 also includes a front panel 42
on one of the sidewalls 38. The front panel 42 can include various
user interface mechanisms such as a display and actuators (e.g.,
buttons, knobs, etc.) (not shown) to display information and
control operation of the electronic device 10. The container 26
further includes mounting features 46 for mounting the electronic
device 10 to a vehicle, such as a police squad car. In the
illustrated embodiment, the mounting features 46 include slots or
recesses formed in the sidewalls 38. In other embodiments, the
container 26 may include other means for mounting the electronic
device 10 in a vehicle or stationary location. Alternatively, the
container 26 may be configured to be mounted, supported, or
otherwise secured in other types of environments.
[0015] The cover 30 is removably coupled to the container 26 by
fasteners 50 (e.g., screws). When the cover 30 is connected to the
container 26, the cover 30 and the container 26 form an enclosure
for the circuit board 18. In some embodiments, such as the
illustrated embodiment, a rubber gasket 54 (FIG. 2) is positioned
between the container 26 and the cover 30 to form a seal to prevent
water, dust, and other contaminants from entering the housing 14.
In one embodiment, the seal is a hermetic seal. As such, the
housing 14 is hermetically-sealed when the cover 30 is securely
fastened to the container 26.
[0016] The illustrated cover 30 includes an outer surface 58 (FIG.
3) and an inner surface 62 (FIG. 4). The inner surface 62,
sometimes referred to as the "dry side," faces the circuit board
18. The outer surface 58, or "wet side," is opposite the inner
surface 62, faces away from the circuit board 18, and is exposed to
the environment. As shown in FIGS. 1-3, the outer surface 58 of the
cover 30 includes a plurality of heat-dissipating fins 66. The
heat-dissipating fins 66 are relatively small, spaced apart
projections that extend outwardly from the outer surface 58. The
illustrated fins 66 are generally arranged in organized rows on the
outer surface 58, but may alternatively be arranged in a different
scattered or organized pattern on the outer surface 58. In some
embodiments, a finned geometry may not be required and the fins 66
may be omitted.
[0017] As shown in FIG. 2, the cover 30 also includes a groove 70
formed in the outer surface 58. In the embodiment illustrated, the
groove 70 extends from a first area 72A of the cover 30 to a second
area 72B of the cover 30 that is spaced apart from the first area
72A. The groove 70 is configured to receive the heat pipe 22. In
the illustrated embodiment, the groove 70 is generally U-shaped. In
other embodiments, the groove 70 may be formed in other shapes
along the outer surface 58 of the cover 30 such as, for example, a
straight line, an arch or curve, a V-shape, an L-shape, an S-shape,
and the like. Alternatively, the heat pipe 22 may be coupled to the
cover 30 to thermally communicate with the outer surface 58 without
the inclusion of the groove 70.
[0018] The cover 30 also has an opening 74 (as illustrated in FIG.
4) connected to the groove 70. The opening 74 extends from the
groove 70 through the inner surface 62 of the cover 30. The opening
74 is a passageway formed through the housing 14 from the
surrounding environment to the enclosure that receives the circuit
board 18. The opening 74 is configured to receive a portion of the
heat pipe 22 to allow the heat pipe 22 to thermally communicate
with the circuit board 18.
[0019] Referring back to FIG. 2, the circuit board 18 is positioned
within the container 26. The circuit board 18 includes electrical
components (e.g., processors, amplifiers, transmitters, receivers,
etc.) that perform the desired functions of the electronic device
10. One of the electrical components 78 is specifically illustrated
in FIG. 2. The illustrated electrical component 78 may be, for
example, a power amplifier that produces heat during operation of
the electronic device 10. It will be appreciated by those of
ordinary skill in the art that the electrical component 78 may be
any component assembled to the circuit board 18 that produces heat
during operation. The electrical component 78 is positioned on the
circuit board 18 so that the component 78 is aligned with the
opening 74 in the cover 30. In the embodiment illustrated in FIG.
5, when the cover 30 is coupled to the container 26, the opening 74
in the cover 30 lies directly over the electrical component 78. In
other embodiments, the opening 74 may be offset from the component
78, provided that a path exists between the opening 74 and the
component 78.
[0020] Referring back to FIG. 2, the heat pipe 22 is mounted to the
cover 30. More particularly, the heat pipe 22 is positioned within
the groove 70 formed in the outer surface 58 of the cover 30. The
heat pipe 22 generally matches the shape and size (e.g., length) of
the groove 70 so that the heat pipe 22 also extends along the outer
surface 58 of the cover 30. In some embodiments, the heat pipe 22
may be soldered, brazed, glued (e.g., with a thermal epoxy or
adhesive), or otherwise hermetically attached to the cover 30 to
secure the heat pipe 22 within the groove 70.
[0021] The illustrated heat pipe 22 is a tube that is filled with
heat transfer fluid to help the pipe spread heat over the housing
14 of the electronic device 10. In one embodiment, the heat pipe 22
is filled with water to transfer heat. Water is suitable for
transferring heat in operating temperatures between about
30.degree. Celsius and about 277.degree. C. In other embodiments,
the heat pipe 22 may be filled with other materials, such as
helium, hydrogen, neon, nitrogen, argon, oxygen, methane, krypton,
ethane, Freon 22, ammonia, Freon 21, Freon 11, pentane, Freon 113,
acetone, methanol, Flutec PP2, ethanol, heptane, toluene, Flutec
PP9, naphthalene, Dowtherm, mercury, sulfur, cesium, rubidium,
potassium, sodium, lithium, calcium, lead, indium, silver, or
combinations of materials, depending on the environmental
temperatures in which the electronic device 10 is expected to
operate.
[0022] The illustrated heat pipe 22 includes a bent portion 82. The
bent portion 82 is a section of the heat pipe 22 that is formed out
of plane with the remainder of the heat pipe 22. In the illustrated
embodiment, the bent portion 82 is formed adjacent a first end 86
of the heat pipe 22. As shown in FIG. 5, the bent portion 82 of the
heat pipe 22 extends into the opening 74 in the cover 30 to
thermally communicate with the electrical component 78 (e.g., the
power amplifier) of the circuit board 18. The bent portion 82 of
the heat pipe 22 directly contacts or abuts the electrical
component 78 to receive heat from the component 78. The heat causes
the heat transfer fluid (e.g., water) in the heat pipe 22 to boil,
or otherwise change phase. When the heat transfer fluid boils and
expands, the fluid moves away from the bent portion 82 to a remote,
second end 90 of heat pipe 22. As the heat transfer fluid moves
from the first end 86 (i.e., the bent portion 82) of the heat pipe
22 to the second end 90 of the heat pipe 22, the fluid transfers
the heat generated by the electrical component 78 over the cover
30. Since the heat pipe 22 generally extends across the entire
cover 30, heat is dissipated over the entire cover 30. In addition,
the fins 66 formed on the outer surface 58 of the cover 30 help
dissipate the heat from the cover 30 to the surrounding
environment.
[0023] In some embodiments, the heat pipe 22 does not include a
bent portion 82. Rather, the heat pipe 22 may extend straight from
(e.g., perpendicular to) the electrical component 78 to the outer
surface 58 of the cover 30. Alternatively, the cover 30 may be
relatively thin (e.g., approximately the same thickness of the heat
pipe 22) so that the heat pipe 22 extends generally parallel to the
electrical component 78, but still directly contacts the component
78.
[0024] In the illustrated embodiment, the heat pipe 22 is in
thermal contact with the cover 30 such that heat is transferred
along dimensions of the housing 14. In other embodiments, the heat
pipe 22 may be thermally coupled only to the heat source (e.g., the
electrical component 78) so that heat is transferred directly from
the heat pipe 22 to the surrounding environment. In further
embodiments, the heat pipe 22 may be coupled to a thermally
advantageous location on the electronic device 10, such as an area
of large thermal mass or a heat sink.
[0025] In the illustrated embodiment, the electronic device 10 also
includes a sealing member 94 positioned at least partially within
the groove 70. The sealing member 94 encloses the heat pipe 22
within the groove 70. In other words, the sealing member 94 helps
fill the groove 70 so that the housing 14 of the electronic device
10 remains properly (for example, hermetically) sealed. As shown in
FIG. 1, the sealing member 94 is generally flush with an upper edge
98 of the cover 30 that defines the groove 70. The sealing member
94 and the upper edge 98 extend from the outer surface 58 of the
cover 30 generally the same distance (i.e., height) as the
heat-dissipating fins 66.
[0026] In the illustrated embodiment, the sealing member 94 is
composed of a thermal epoxy or thermally-conductive epoxy, such as
Thermalbond.RTM. manufactured by Saint-Gobain. In other
embodiments, the sealing member 94 may be composed of solder, a
silicone-based sealing compound, or the like. In further
embodiments, the sealing member 94 may be a pre-formed gasket this
is placed within and fills the groove 70. In some embodiments, the
sealing member 94 may be omitted. In such embodiments, the heat
pipe 22 itself may fill and seal the groove 70 in the cover 30.
[0027] As shown in FIGS. 2 and 4, the illustrated electronic device
10 further includes an electromagnetic interference (EMI) shield.
The EMI shield includes a first track 102 (FIG. 4) coupled to the
inner surface 62 of the cover 30. The first track 102 may include,
for example, a metallic gasket formed on the inner surface 62. The
EMI shield also includes a second track 106 (FIG. 2) coupled to the
circuit board 18. The second track 106 may include, for example, a
gold line that is printed or otherwise formed on the circuit board
18. The first track 102 on the cover 30 cooperates with the second
track 106 on the circuit board 18 to create the EMI shield within
the housing 14 of the electronic device 10. When the cover 30 is
coupled to the container 26, the first track 102 (FIG. 4) lays on
top of the second track 106 (FIG. 6), connecting the tracks 102,
106 together. In this position, the tracks 102, 106 contact each
other and together form a perimeter around the electrical component
78 (and other components on the circuit board 18) to separate or
isolate the electrical component 78 from the other components
within the electronic device 10, and from external electromagnetic
interferences.
[0028] As shown in FIGS. 2 and 4, the opening 74 for the heat pipe
22 is positioned within the perimeter defined by the tracks 102,
106. This arrangement allows the heat pipe 22 to contact the
electrical component 78 without disrupting the EMI shield. The heat
pipe 22 only extends through the cover 30 in an area that is
already bounded by the tracks 102, 106. In addition, the remainder
of the heat pipe 22 is positioned on the outer surface 58 of the
cover 30 so that the heat pipe 22 does not extend across and break
the track 102 formed on the inner surface 58 of the cover 30.
[0029] Although the illustrated electronic device 10 is shown and
described with one heat pipe 22, in other embodiments, an
electronic device may include multiple heat pipes. Each heat pipe
may thermally communicate with a different electrical component
within the device, or may communicate with the same electrical
component. In such embodiments, the housing of the electronic
device may include multiple openings so that each heat pipe extends
through the housing to the electrical component(s) through its own
opening. The heat pipes may all be located on the same surface of
the housing (e.g., the outer surface 58 of the cover 30) or may be
located on different surfaces of the housing (e.g., one heat pipe
on the outer surface 58 of the cover 30, one heat pipe on the
sidewall 38 of the container 26, one heat pipe on the base 34 of
the container 26, etc.).
[0030] In some embodiments, one heat pipe may thermally communicate
with multiple electrical components. For example, the heat pipe may
include an elongated bent portion that contacts two adjacent
electrical components within the electronic device 10.
Alternatively, the heat pipe may include multiple bent portions,
each of which contacts a separate electrical component. Each bent
portion may extend through a separate opening or the same opening
within the cover 30 of the electronic device 10.
[0031] The externally-mounted heat pipe 22 described above
facilitates dissipating heat over a widespread area of the
electronic device 10. In addition, the heat pipe 22 allows the
electronic device 10 to remain sealed. Furthermore, the heat pipe
22 does not interfere with or disrupt EMI shielding within the
electronic device 10.
[0032] Embodiments of the invention have been tested in an
electronic device with a 70 Watt heat load, such as the two-way
radio illustrated in FIGS. 1 through 5. The heat pipe 22 uniformly
spreads heat around the housing 14. The housing 14 radiates
temperatures around about 65.degree. Celsius to 75.degree. Celsius.
In addition, the heat source of the mobile product (i.e., the
electrical component 78 in contact with the heat pipe 22) is
maintained at a temperature that is about 40.degree. Celsius to
50.degree. Celsius lower than comparable devices without heat
pipes. The net heat capacity of the mobile product is, thereby,
improved by about 15 Watt to 20 Watt. To achieve similar
heat-dissipation results without a heat pipe, the comparable
devices would need to be, for example, about 40 percent taller.
[0033] In a portable electronic device with a 13 Watt heat load,
such a handheld radio, a heat pipe transfers heat to a cooler
region of the housing. In addition, the heat source of the portable
product is about 15.degree. Celsius to 20.degree. Celsius cooler
(and adjacent components are about 5.degree. Celsius cooler) that
comparable devices without heat pipes. The net heat capacity of the
portable product is, thereby, improved by about 1 Watt. To achiever
similar heat-dissipation results without a heat pipe, the
comparable devices would need to be, for example, about 25 percent
longer.
[0034] During testing, it was found that embodiments in which the
heat pipe directly contacts the electrical component achieved the
greatest level of cooling in comparison, for example, to
embodiments in which an indirect thermal communication occurred.
For example, instead of forming an opening in the housing, a
depression or well may be formed and a thin layer of the housing
left intact to provide indirect thermal communication between the
heat pipe and the electrical component. This improves sealing of
the housing, but was found to reduce cooling as the thermal
transmission from the electrical component to the heat pipe
occurred through the thin layer rather than directly.
[0035] In the foregoing specification, specific embodiments have
been described. However, one of ordinary skill in the art
appreciates that various modifications and changes can be made
without departing from the scope of the invention as set forth in
the claims below. Accordingly, the specification and figures are to
be regarded in an illustrative rather than a restrictive sense, and
all such modifications are intended to be included within the scope
of present teachings.
[0036] The benefits, advantages, solutions to problems, and any
element(s) that may cause any benefit, advantage, or solution to
occur or become more pronounced are not to be construed as a
critical, required, or essential features or elements of any or all
the claims. The invention is defined solely by the appended claims
including any amendments made during the pendency of this
application and all equivalents of those claims as issued.
[0037] Moreover in this document, relational terms such as first
and second, top and bottom, and the like may be used solely to
distinguish one entity or action from another entity or action
without necessarily requiring or implying any actual such
relationship or order between such entities or actions. The terms
"comprises," "comprising," "has", "having," "includes",
"including," "contains", "containing" or any other variation
thereof, are intended to cover a non-exclusive inclusion, such that
a process, method, article, or apparatus that comprises, has,
includes, contains a list of elements does not include only those
elements but may include other elements not expressly listed or
inherent to such process, method, article, or apparatus. An element
proceeded by "comprises . . . a", "has . . . a", "includes . . .
a", "contains . . . a" does not, without more constraints, preclude
the existence of additional identical elements in the process,
method, article, or apparatus that comprises, has, includes,
contains the element. The terms "a" and "an" are defined as one or
more unless explicitly stated otherwise herein. The terms
"substantially", "essentially", "approximately", "about" or any
other version thereof, are defined as being close to as understood
by one of ordinary skill in the art, and in one non-limiting
embodiment the term is defined to be within 10%, in another
embodiment within 5%, in another embodiment within 1% and in
another embodiment within 0.5%. The term "coupled" as used herein
is defined as connected, although not necessarily directly and not
necessarily mechanically. A device or structure that is
"configured" in a certain way is configured in at least that way,
but may also be configured in ways that are not listed.
[0038] The Abstract of the Disclosure is provided to allow the
reader to quickly ascertain the nature of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. In addition,
in the foregoing Detailed Description, it can be seen that various
features are grouped together in various embodiments for the
purpose of streamlining the disclosure. This method of disclosure
is not to be interpreted as reflecting an intention that the
claimed embodiments require more features than are expressly
recited in each claim. Rather, as the following claims reflect,
inventive subject matter lies in less than all features of a single
disclosed embodiment. Thus the following claims are hereby
incorporated into the Detailed Description, with each claim
standing on its own as a separately claimed subject matter.
* * * * *