U.S. patent application number 09/916932 was filed with the patent office on 2003-01-30 for high performance cooling device.
Invention is credited to Hegde, Shankar.
Application Number | 20030019609 09/916932 |
Document ID | / |
Family ID | 25438102 |
Filed Date | 2003-01-30 |
United States Patent
Application |
20030019609 |
Kind Code |
A1 |
Hegde, Shankar |
January 30, 2003 |
HIGH PERFORMANCE COOLING DEVICE
Abstract
A low-cost, fan assisted cooling device is disclosed. The
cooling device includes a narrow bottom and broad top shape to
optimize a material versus performance ratio. A plurality of vanes
surround a central heat mass and an inside surface of the vanes
define a chamber that surrounds the heat mass. A portion of each
vane is split into a plurality of fins and both the vanes and the
fins have a surface area that increase in a radially outward
direction from an axis of the heat mass. The heat mass includes a
boss that is surrounded by a groove. Both the boss and the grove
have arcuate surface profiles. The vanes, the fins, the boss, and
the groove efficiently dissipate heat when a fan or the like forces
air into the chamber thereby producing air flows in three different
directions. In a first direction, the air flows out of the chamber
through the vanes. In a second direction, a low pressure region in
the chamber induces air from outside the chamber to flow through
the fins. In a third direction, the low pressure region induces an
airflow over the groove and boss. Openings between the vanes are
angled and offset from an orientation of the fans blades to
minimize the airflow shock losses thereby reducing fan noise. The
vanes and the fins can be homogeneously formed with the heat
mass.
Inventors: |
Hegde, Shankar;
(Annassandrapalya Bangalore, IN) |
Correspondence
Address: |
HEWLETT-PACKARD COMPANY
Intellectual Property Administration
P.O. Box 272400
Fort Collins
CO
80527-2400
US
|
Family ID: |
25438102 |
Appl. No.: |
09/916932 |
Filed: |
July 27, 2001 |
Current U.S.
Class: |
165/80.3 ;
165/121; 257/E23.099 |
Current CPC
Class: |
H01L 23/467 20130101;
H01L 2924/0002 20130101; H01L 2924/0002 20130101; H01L 2924/00
20130101 |
Class at
Publication: |
165/80.3 ;
165/121 |
International
Class: |
F28F 001/00; F24H
003/02; F28F 007/00 |
Claims
What is claimed is:
1. A cooling device for dissipating heat from a component,
comprising: a heat mass including a boss having a convex arcuate
surface profile and a groove surrounding the boss and having a
concave arcuate surface profile, the groove and the boss are
symmetrically positioned about an axis of the heat mass; a heat
conductive base in contact with the heat mass and including a
mounting surface adapted to contact the component; a plurality of
vanes in contact with the heat mass and spaced apart to define a
primary slot therebetween and extending to the heat mass, the vanes
have a surface area that increases in a radially outward direction
from the axis, the vanes including a top face, an aerodynamically
profiled inner wall including a first portion extending from the
groove and terminating at a second portion that extends to the top
face, the inner walls of the vanes defining a chamber that
surrounds the groove, an outer wall having a surface profile that
widens from a bottom of the heat mass to the top face and includes
therebetween a smooth curved portion, a draft portion, and a smooth
radially outward portion, and the vanes including at least one
secondary slot extending through a portion of each vane to define a
plurality of fins in each vane; and wherein an air flow entering
the chamber exits through the primary slots and a bottom portion of
the secondary slots in an exhaust flow that dissipates heat from
the vanes and the fins, the exhaust flow creates a low pressure
region within the chamber that induces an intake flow into the
chamber through the secondary slots and a top portion of the
primary slots thereby dissipating heat from the fins and the vanes,
and the low pressure region induces a surface flow along the first
and second portions of the inner wall so that the surface flow
passes over the groove and the boss to dissipate heat from the heat
mass.
2. The cooling device as set forth in claim 1 wherein the heat
mass, the base, and the vanes are homogeneously formed.
3. The cooling device as set forth in claim 1 wherein the mounting
surface is substantially perpendicular to the axis.
4. The cooling device as set forth in claim 1 wherein the mounting
surface further comprises: a plurality of projections that extend
outward of the mounting surface; and a thermal interface material
in contact with the mounting surface and positioned between the
projections, and wherein the projections are adapted to protect the
thermal interface material from damage when the base is in contact
with the component.
5. The cooling device as set forth in claim 1 and further
comprising at least one fan positioned adjacent to the top face and
positioned over the chamber so that an air flow generated by the
fan produces the air flow into the chamber.
6. The cooling device as set forth in claim 5 and further
comprising a mounting ring adapted to abut against the smooth
radially outward portion and including a plurality of mounting
fixtures adapted to receive a fastener that connects the fan with
the mounting ring such that the fan is fixedly connected with the
top face.
7. The cooling device as set forth in claim 6 wherein at least a
portion of the top face is a substantially planar portion and the
fan is seated on the substantially planar portion when the fan is
connected with the top face.
8. The cooling device as set forth in claim 1 wherein the vanes are
tangentially oriented to a predetermined diameter of a circle
centered about the axis.
9. The cooling device as set forth in claim 8 where in the
predetermined diameter is from about 3.0 millimeters to about 12.0
millimeters.
10. The cooling device as set forth in claim 1 wherein the vanes
are inclined at an angle with respect to the axis.
11. The cooling device as set forth in claim 10 wherein the angle
at which the vanes are inclined is from about 5.0 degrees to about
25.0 degrees.
12. The cooling device as set forth in claim 10 wherein the angle
at which the vanes are inclined comprises a first angle from about
10.0 degrees to about 25.0 degrees, the first angle measured along
the smooth radially outward portion, and a second angle from about
5.0 degrees to about 18.0 degrees measured along the smooth curved
portion.
13. The cooling device as set forth in claim 1 wherein the arcuate
surface profile of the boss is a profile selected from the group
consisting of a sphere, a cone, and a frustum of a cone.
14. The cooling device as set forth in claim 1 wherein the arcuate
surface profile of the groove is a semi-circular profile.
15. The cooling device as set forth in claim 1 wherein the primary
slot further includes a first arcuate profile along the heat mass
and the first arcuate profile is a portion of an arc having a
radius from about 38.0 millimeters to about 45.0 millimeters.
16. The cooling device as set forth in claim 1 wherein the
secondary slot extends to the heat mass and the secondary slot
further includes a second arcuate profile along the heat mass and
the second arcuate profile is a portion of a n arc having a radius
from about 31.0 millimeters to about 38.0 millimeters.
17. The cooling device as set forth in claim 1 wherein the first
portion of the inner wall is a sloped surface and the second
portion of the inner wall is a concave arcuate surface.
18. The cooling device as set forth in claim 1 wherein the base
further comprises: a cylindrical neck inset from the base and
defining an attachment groove between the base and the heat mass;
and a pair of flats substantially perpendicular to the mounting
surface and positioned in parallel opposition to each other.
19. The cooling device as set forth in claim 1 and further
comprising: a shroudless fan including a space frame for supporting
the fan and for positioning the fan adjacent to the top face and
over the chamber so that an air flow generated by the fan produces
the air flow into the chamber, the space frame including a
plurality of arms that span the top face, the arms include fingers
at an end thereof, and the fingers are adapted to clamp the space
frame to the smooth radially outward portion of the outer wall.
20. A system for dissipating heat, comprising: a cooling device
including: a heat mass including a boss having a convex arcuate
surface profile and a groove surrounding the boss and having a
concave arcuate surface profile, the groove and the boss are
symmetrically positioned about an axis of the heat mass, a heat
conductive base in contact with the heat mass and including a
mounting surface adapted to contact the component, a plurality of
vanes in contact with the heat mass and spaced apart to define a
primary slot therebetween and extending to the heat mass, the vanes
have a surface area that increases in a radially outward direction
from the axis, the vanes including a top face, an aerodynamically
profiled inner wall including a first portion extending from the
groove and terminating at a second portion that extends to the top
face, the inner walls of the vanes defining a chamber that
surrounds the groove, an outer wall having a surface profile that
widens from a bottom of the heat mass to the top face and includes
therebetween a smooth curved portion, a draft portion, and a smooth
radially outward portion, and the vanes including at least one
secondary slot extending through a portion of each vane to define a
plurality of fins in each vane, and wherein an air flow entering
the chamber exits through the primary slots in an exhaust flow that
dissipates heat from the vanes and the fins, the exhaust flow
creates a low pressure region within the chamber that induces an
intake flow into the chamber through the secondary slots thereby
dissipating heat from the fins, and the low pressure region induces
a surface flow along the first and second portions of the inner
wall so that the surface flow passes over the groove and the boss
to dissipate heat from the heat mass; a fan for generating the air
flow into the chamber, the fan connected with the top face; a
component including a component face; and a base mount for urging
the mounting surface and the component face into contact with each
other so that heat generated by the component is thermally
communicated into the cooling device.
21. The system as set forth in claim 20 wherein the component is
carried by a support unit selected from the group consisting of a
socket, a substrate, and a PC board, and the base mount is
removably connected with the support unit.
22. The system as set forth in claim 20 wherein the mounting
surface further comprises: a plurality of projections that extend
outward of the mounting surface; and a thermal interface material
in contact with the mounting surface and the component face and
positioned between the projections, and wherein the projections are
adapted to protect the thermal interface material from damage when
the mounting surface is in contact with the component face.
23. The system as set forth in claim 20 wherein the base further
comprises: a cylindrical neck inset from the base and defining an
attachment groove between the base and the heat mass; and a pair of
flats substantially perpendicular to the mounting surface and
positioned in parallel opposition to each other.
24. The system as set forth in claim 23 wherein the mounting
surface further comprises: a plurality of projections that extend
outward of the mounting surface; and a thermal interface material
in contact with the mounting surface and the component face and
positioned between the projections, and wherein the projections are
adapted to protect the thermal interface material from damage when
the mounting surface is in contact with the component face.
25. The system as set forth in claim 20 wherein the fan is a
shroudless fan including a space frame for supporting the fan and
for positioning the fan adjacent to the top face and over the
chamber so that the air flow generated by the fan produces the air
flow into the chamber, the space frame including a plurality of
arms that span the top face, the arms include fingers at an end
thereof, and the fingers are adapted to clamp the space frame to
the smooth radially outward portion of the outer wall.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a cooling device
for removing heat from a component connected with the cooling
device. More specifically, the present invention relates to a
cooling device for removing heat from an electronic component
connected with the cooling device.
BACKGROUND OF THE INVENTION
[0002] It is well known in the electronics art to place a heat sink
in contact with an electronic device so that waste heat generated
by operation of the electronic device is thermally transferred into
the heat sink thereby cooling the electronic device. With the
advent of high clock speed electronic devices such as
microprocessors (pP), digital signal processors (DSP), and
application specific integrated circuits (ASIC), the amount of
waste heat generated by those electronic devices and the operating
temperature of those electronic devices are directly proportional
to clock speed. Therefore, higher clock speeds result in increased
waste heat generation which in turn increases the operating
temperature of the electronic device. However, efficient operation
of the electronic device requires that waste heat be continuously
and effectively removed.
[0003] Heat sink devices came into common use as a preferred means
for dissipating waste heat from electronic devices such as the
types described above. In a typical application, a component to be
cooled is carried by a connector that is mounted on a PC board. A
heat sink is mounted on the component by attaching the heat sink to
the connector using a clip or fasteners, for example.
Alternatively, the heat sink is mounted to a PC board that carries
the electronic device and fasteners or the like are used to connect
the heat sink to the PC board via holes that are drilled in the PC
board.
[0004] The need to drill holes can be one disadvantage to using
fasteners because the fasteners or other mounting hardware used for
connecting the heat sink to the PC board are usually electrically
conductive and there is a risk of an electrical short due to
contact between a PC board trace and the mounting hardware.
Moreover, to avoid electrical shorts, the PC board traces can be
routed around the hole, but that routing requires keep out zones
that can complicate the routing of the traces.
[0005] Typically, a heat sink used in conjunction with a modern
high clock speed electronic device will use an electrical fan
mounted on top of the heat sink or within a cavity formed by
cooling fins/vanes of the heat sink. The cooling fins increase the
surface area of the heat sink and maximize heat transfer from the
heat sink to ambient air that surrounds the heat sink. The fan
causes air to circulate over and around the cooling fins thereby
transferring heat from the cooling fins into the ambient air.
[0006] As mentioned previously, with continuing increases in clock
speed, the amount of waste heat generated by electronic devices has
also increased. Accordingly, to adequately cool those electronic
devices, larger heat sinks and/or larger fans are required.
Increasing the size of the heat sink results in a greater thermal
mass and a greater surface area from which the heat can be
dissipated. Increases in fan size provide for more air flow through
the cooling fins.
[0007] There are disadvantages to increased fan and heat sink size.
First, if the size of the heat sink is increased in a vertical
direction (i.e. in a direction transverse to the PC board), then
the heat sink is tall and may not fit within a vertical space in
many applications, such as the chassis of a desktop computer.
Second, if the PC board has a vertical orientation, then a heavy
and tall heat sink can mechanically stress the PC board and/or the
electronic device resulting in a device or PC board failure.
[0008] Third, a tall heat sink will require additional vertical
clearance between the heat sink and a chassis the heat sink is
contained in to allow for adequate air flow into or out of the fan.
Fourth, if the heat sinks size is increased in a horizontal
direction, then the amount of area available on the PC board for
mounting other electronic devices is limited. Fifth, when the heat
sink has a cylindrical shape formed by the fins it is often not
possible to mount several such heat sinks in close proximity to
each other because air flow into and out of the fins is blocked by
adjacent heat sinks with a resulting decrease in cooling
efficiency.
[0009] Finally, increases in fan size to increase cooling capacity
often result in increased noise generation by the fan. In many
applications such as the desktop computer or a portable computer,
it is highly desirable to minimize noise generation. In portable
applications that depend on a battery to supply power, the
increased power drain of a larger fan is not an acceptable solution
for removing waste heat.
[0010] In the above mentioned heat sink with cooling fins there are
additional disadvantages to mounting the fan within a cavity formed
by the fins. First, a substantial portion of a heat mass of the
heat sink is partially blocked by the fan because the fan is
mounted directly on the heat mass and therefore blocks a potential
path for heat dissipation from the heat mass because air from the
fan does not circulate over the blocked portion of the heat
mass.
[0011] Second, without the fan, a depth of the fins could extend
all the way to a center of the heat mass; however, the depth and
surface area of the fins is reduced by a diameter of the fan
because the fan is mounted in a cavity having a diameter that is
slightly larger than the fans diameter to provide clearance for the
fans blades. Consequently, the heat mass of the heat sink must be
made broader to compensate for the reduced surface area of the
fins. The broader heat mass increases the size, cost, and weight of
the heat sink.
[0012] Third, the reduced depth of the fins makes it easier for the
fins to be bent if damaged. One possible consequence of a bent fin
is that it will contact and damage the fan blades and/or cause the
fan to stall thereby damaging the fan or causing the fan to fail.
Fourth, because the fan is mounted in the cavity formed by the
fins, power leads for the fan must be routed through a space
between the fins. Sharp edges on the fins can cut the power leads
or cause an electrical short. In either case, the result is that
the fan will fail. Fifth, glue is typically used to mount the fan
to the heat sink and the glue can get into the fan and cause the
fan to fail. Any of the above mentioned fan failure modes can lead
to a failure of the electronic device the heat sink was designed to
cool because air circulation generated by the fan is essential to
effectively dissipate waste heat from the electronic device.
[0013] Thus, there exists a need for a cooling device that
overcomes the aforementioned disadvantages associated with fan
assisted heat sinks.
SUMMARY OF THE INVENTION
[0014] Broadly, the present invention is embodied in a cooling
device for dissipating waste heat from a component to be cooled.
The cooling device includes a heat mass with an arcuate boss that
is surrounded by an arcuate groove. A heat conductive base
including a mounting surface for connecting the cooling device with
the component to be cooled is connected with the heat mass.
Extending from the heat mass are a plurality of vanes that are
spaced apart from each other to define a primary slot between
adjacent vanes and extending to the heat mass. The vanes have a
surface area that increases in a radially outward direction from an
axis of the heat mass and a portion of the surface area of the
vanes also increase in a direction that is along the axis. The
vanes include a top face upon which a fan can be mounted, an
aerodynamically profiled inner wall that defines a chamber that
surrounds the boss and the groove, and an outer wall including a
surface profile that widens from the base to the top face and
includes a smooth curved portion, a draft portion, and a smooth
radially outward portion. Furthermore, the surface area of the
vanes is increased by a plurality of fins formed in each vane by a
secondary slot extending through a portion of the vane.
[0015] An air flow entering the chamber creates a three-dimensional
air flow that dissipates heat from the cooling device. First, the
air flow exits through the vanes and a portion of the fins in an
exhaust flow that dissipates heat from the vanes and the fins.
Second, the exhaust flow creates a low pressure region within the
chamber that induces an intake flow into the chamber through a
major portion of the fins and a top portion of the vanes thereby
dissipating heat from the fins and the vanes. Third, the low
pressure region induces a surface flow along the inner wall so that
the surface flow wets the groove and the boss as it passes over the
groove and the boss to dissipate heat from the heat mass.
[0016] The cooling device of the present invention solves the
aforementioned disadvantages of prior heat sinks. The cooling
device can be mounted to a component to be cooled by using a clip
to connect the cooling device with a connector that carries the
component. Therefore, holes need not be drilled in a PC board to
mount the cooling device. The cooling device employs vanes that
extend deep within the heat mass and the surface area of the vanes
increases from a bottom of the cooling device to a top of the
cooling device and in a radially outward direction from the heat
mass. Furthermore, each vane is split into at least two fins thus
further increasing the surface area available for cooling. As a
result, the cooling device need not be made taller to increase vane
surface area and the cooling device need not be made wider to
increase the size of the heat mass.
[0017] The top of the cooling device is adapted to mount a fan so
that the heat mass is not blocked by the fan and air can circulate
over the heat mass thus further dissipating heat from the cooling
device. The fan can include a shroud that surrounds the blades
unlike the fans that are mounted in a cavity formed by fins of
prior heat sink devices. However, the cooling device can also mount
a fan without a shroud using a clip or space frame to mount the fan
to the top of the cooling device. Because the fan is mounted on top
of the cooling device, the wires of the power leads for the fan are
not routed through the vanes or fins thereby eliminating the risk
of the wires being cut or short circuited.
[0018] The shape of the cooling device (wider at the top than at
the bottom) allows for several of the cooling devices to be placed
adjacent to each other without blocking air flow into and out of
the vanes and fins.
[0019] The vanes of the cooling device can be tangentially oriented
with a circle centered on an axis of the heat mass and the vanes
can be inclined at an angle with respect to the axis such that the
angle of inclination substantially matches or closely approximates
a pitch angle of the blades of a fan. The tangential orientation
and the inclination of the vanes reduces fan noise due to air shock
losses.
[0020] Other aspects and advantages of the present invention will
become apparent from the following detailed description, taken in
conjunction with the accompanying drawings, illustrating by way of
example the principles of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a cross-sectional view along line A-A of FIG. 2a
of a cooling device according to the present invention.
[0022] FIGS. 2a and 2b are top plan views of a cooling device
according to the present invention.
[0023] FIGS. 2c is detailed view of a portion of the top plan view
of FIG. 2b.
[0024] FIG. 3a is a cross-sectional view along line A-A of FIG. 3b
of air flow into and out of a cooling device according to the
present invention.
[0025] FIG. 3b is a top plan view of air flow into and out of a
cooling device according to the present invention.
[0026] FIG. 4 is a cross-sectional view of a cooling device with a
base with an inset neck portion according to the present
invention.
[0027] FIGS. 5a and 5b are side views of a cooling device with
vanes inclined at an angle according to the present invention.
[0028] FIG. 6 is a top plan view illustrating a cooling device
having vanes with a tangential orientation according to the present
invention.
[0029] FIG. 7 is a profile view of a mounting ring for connecting a
fan with a cooling device according to the present invention.
[0030] FIG. 8 is a side view of a fan mounted to a cooling device
according to the present invention.
[0031] FIG. 9 is a cross-sectional view illustrating various
dimensional relationships between a fan and a cooling device
according to the present invention.
[0032] FIG. 10 is a side view of a space frame mounting a fan to a
cooling device according to the present invention.
[0033] FIG. 11 is a side view of a cooling device with a base
having projections and a thermal interface material according to
the present invention.
[0034] FIGS. 12a through 12d are various views of a cooling device
with a base having projections and flats according to the present
invention.
[0035] FIG. 13 is a side view of a system for dissipating heat
according to the present invention.
[0036] FIG. 14 is a side view of a system for dissipating waste
heat according to the present invention.
[0037] FIGS. 15a through 15c illustrate insertion of a cooling
device into a spring clip according to the present invention.
DETAILED DESCRIPTION
[0038] In the following detailed description and in the several
figures of the drawings, like elements are identified with like
reference numerals.
[0039] As shown in the drawings for purpose of illustration, the
present invention is embodied in a cooling device for dissipating
heat from a component that is in thermal communication with the
cooling device. The thermal communication can be by direct contact
between the cooling device and the component or by an intermediate
material positioned between the cooling device and the component as
will be described below. The component can be any heat source such
as an electrical component, for example. The cooling device
includes a heat mass with a boss surrounded by a groove and with
the groove and the boss symmetrically positioned about an axis of
the heat mass. The boss has a convex arcuate surface profile and
the groove has a concave arcuate surface profile. A heat conductive
base is in contact with the heat mass and includes a mounting
surface adapted to contact the component to be cooled.
[0040] A plurality of vanes surround the heat mass and the vane are
spaced apart from one another to define a primary slot between
adjacent vanes. The primary slot extends to the heat mass so that
an exhaust flow of air cools the vanes and the heat mass. The vanes
have a surface area that increases in a radially outward direction
from the axis and in a direction along the axis. A plurality of
fins are formed in each vane by a secondary slot extending through
a portion of each vane.
[0041] The vanes include a top face and an aerodynamically profiled
inner wall that includes a first portion extending from the groove
and terminating at a second portion that extends to the top face.
The inner wall defines a chamber that surrounds the groove. The
vanes also include an outer wall having a surface profile that
widens from the base to the top face. The surface profile includes
a smooth curved portion, a draft portion, and a smooth radially
outward portion.
[0042] An air flow entering the chamber creates a three-dimensional
air flow that dissipates heat from the cooling device. First, the
air flow exits the primary slots and a bottom portion of the
secondary slots in an exhaust flow that dissipates heat from the
vanes and the fins. Second, the exhaust flow creates a low pressure
region within the chamber that induces an intake flow into the
chamber through a major portion of the secondary slots and a top
portion of the primary slots thereby dissipating heat from the fins
and the vanes. Third, the low pressure region induces a surface
flow along the first and second portions of the inner wall so that
the surface flow wets the groove and the boss as it passes over the
groove and the boss to dissipate heat from the heat mass.
[0043] In FIGS. 1 and 2a through 2c, a cooling device 10 for
dissipating heat from a component (not shown) includes a heat mass
11, a boss 13, and a groove 15 that completely surrounds the boss
13. The boss 13 and the groove 15 are symmetrically positioned
about an axis Z-Z of the heat mass 11. The boss 13 has a convex
arcuate surface profile and the groove 15 has a concave arcuate
surface profile. The arcuate profiles of the boss and the groove
(13, 15) blend into each other as illustrated by dashed line a. The
cooling device 10 further includes a heat conductive base 17 (base
17 hereinafter) that is in contact with the heat mass 11 and the
base 17 includes a mounting surface 19 for contacting a surface of
the component to be cooled. A plurality of vanes 21 are in contact
with the heat mass 11 and the vanes 21 are spaced apart from one
another to define a primary slot P (see FIGS. 2a and 2c) between
adjacent vanes 21. The vanes 21 have a surface area that increases
in a radially outward direction from the axis Z-Z as indicated by
the dashed arrow r. At least a portion of the vanes 21 have a
surface area that increases in a direction along the axis Z-Z as
shown by dashed arrow y.
[0044] Preferably, the primary slot P extends to the heat mass 11
and the primary slot P includes a first arcuate surface profile 21a
along the heat mass 11. The first arcuate profile 21a terminates on
a plane H-H (see FIG. 1). The plane H-H can be coincident with a
bottom surface 11a of the heat mass 11. It is also preferable that
the vanes 21 are equidistantly spaced apart from each another. By
extending the primary slot P to the heat mass 11, air flow through
the vanes 21 also wets the heat mass 11 to dissipate heat
therefrom. The first arcuate surface profile 21 a can be an arc
having a radius from about 38.0 millimeters to about 45.0
millimeters.
[0045] One advantage of the cooling device 10, is that a fan (not
shown) for generating an air flow is not mounted on the heat mass
11. Consequently, the vanes 21 can extend deep into the heat mass
11 (as illustrated by arrow e) and the depth of the vanes 21
provides a large surface area for efficient dissipation of waste
heat and exposes the heat mass 11 to an air flow (see FIGS. 3a and
3b) that wets over the boss 13 and the groove 15 so that additional
waste heat can be dissipated from the heat mass 11.
[0046] The vanes 21 also include a top face 29, an aerodynamically
profiled inner wall 26 including a first portion 25 that extends
from the groove 15 and terminates at a second portion 27 that
extends to the top face 29. The first portion 25 blends with the
arcuate profile of the groove 15 as illustrated by dashed line b
and the first portion 25 blends with the second portion 27 as
illustrated by dashed line C. The second portion 27 blends with the
top face 29 as illustrated by dashed line d. The inner wall 26 can
include additional portions and the present invention is not to be
construed as being limited to the first and second portions (25,
27). The inner wall 26 defines a chamber 30 that surrounds the
groove 15.
[0047] In one embodiment of the present invention, as illustrated
in FIGS. 1, 2c, and 4, the first portion 25 of the inner wall 26 is
a slope surface and the second portion 27 of the inner wall 26 is a
concave arcuate surface. The sloped and concave arcuate surfaces
aerodynamically interact with an air flow into the chamber 30 so
that the air flows along the first and second portions (25, 27) of
the inner wall 26 and wet over the groove and the boss (15, 13) to
dissipate heat from the heat mass 11 as will be described below in
reference to FIGS. 3a and 3b.
[0048] The first portion 25 can be inclined at an angle .psi. with
respect to the axis Z-Z as illustrated in FIG. 1. The angle .psi.
can be in a range from about 15.0 degrees to about 75.0 degrees. If
the vanes 21 have a tangential orientation with a circle about the
axis Z-Z as will be discussed below in reference to FIG. 6, then
the first portion 25 will have a tangential orientation with the
groove 15. The angle .psi. will vary based primarily on an output
of a fan (not shown) in cubic feet per minute (CFM).
[0049] The vanes 21 further include an outer wall 32 having a
surface profile that widens from a bottom 11a of the heat mass 11
to the top face 29 and includes a smooth curved portion 33, a draft
portion 35, and a smooth radially outward portion 37. The draft
portion 35 an be substantially parallel to the axis Z-Z or the
draft portion 35 can be inclined at an angle .lambda. as
illustrated in FIG. 4.
[0050] In FIGS. 2a through 2c, the vanes 21 include at least one
secondary slot S that extends through a portion of each vane 21 to
define a plurality of fins 23 (two are shown) in each vane 21. By
splitting at least a portion of each vane 21 into a plurality of
fins 23, the available surface area for dissipating waste heat is
increased and the secondary slot S provides an additional air flow
path between the fins 23 that further increases waste heat
dissipation.
[0051] In another embodiment of the present invention, the
secondary slot S extends to the heat mass 11 and the secondary slot
S includes a second arcuate profile 23a (see dashed line in FIG. 1)
along the heat mass 11. The second arcuate profile 23a terminates
on the plane H-H. By extending the secondary slot S to the heat
mass 11, air flow through the fins 23 also wets the heat mass 11 to
dissipate heat therefrom. The second arcuate profile 23a can be an
arc having a radius from about 31.0 millimeters to about 38.0
millimeters.
[0052] Reference points for a center of the above mentioned
radiuses (i.e. for 21a and 23a) will be positioned outside the
cooling device 10 and the actual location of the center will depend
on the arcs radius. However, the position of the center of the
radius will be at least about 5.0 millimeters out side of the
cooling device 10 to accommodate a cutting tool used in a machining
process for making the cooling device 10. The position of the
center of the radius is a limitation imposed by a machining process
that uses cutting wheels to form the vanes 21 and the fins 23. If
the vanes 21 and the fins 23 can be diecasted or impact forged,
then the arc radius could be reduced and the position of the center
of the radius could come inside the cooling device 10. The cooling
device 10 can be made amendable to a diecasted or impact forged
process by reducing the number of vanes 21.
[0053] In FIGS. 3a and 3b, heat dissipation by an air flow F
entering the chamber 30 is illustrated. A portion of the air flow F
exits the chamber 30 through the primary slots P and a bottom
portion of the secondary slots S (not shown) in an exhaust flow E.
The exhaust flow E passes over the vanes 21 and the fins 23 and
dissipates heat therefrom. A low pressure region AP is created
within the chamber 30 by the exhaust flow E. Consequently, the low
pressure region .DELTA.P induces an intake flow I into the chamber
30 through a major portion of the secondary slots S and a top
portion of the primary slots P (not shown) thereby dissipating heat
from the fins 23 and the vanes 21. The low pressure region .DELTA.P
also induces a surface flow B along the aerodynamically shaped
first and second portions (25, 27) of the inner wall 26. The
surface flow B passes over the arcuate profiles of the groove and
boss (15, 13) thereby dissipating heat from the heat mass 11 as the
surface flow B circulates back towards (i.e. it is a balancing air
flow) the low pressure region .DELTA.P. Therefore, another
advantage of the cooling device 10 is that waste heat is
efficiently dissipated by a three-dimensional air flow (comprising
E, I, and B) through the vanes 21 and the fins 23, and passing over
the groove and boss (15, 13).
[0054] In one embodiment of the present invention, the arcuate
surface profile of the boss 13 includes but is not limited to a
profile of a sphere, a frustum of a sphere, a cone, and a frustum
of a cone. In FIG. 1, the boss 13 has a conical surface profile. On
the other hand, the surface profile could also be spherical. In
FIG. 4, the boss 13 has a surface profile that is a frustum 13a of
a cone. The boss 13 could also have a surface profile that is a
frustum 13a of a sphere.
[0055] In another embodiment of the present invention, the arcuate
surface profile of the groove 15 includes but is not limited to a
semi-circular profile as illustrated in FIGS. 1 and 4. Preferably,
the boss 13 has a diameter d.sub.B (see FIG. 1) that is less than a
diameter of a hub 79 of a fan 70 (see FIG. 9). The groove 15 should
have a radius r.sub.G (see FIG. 9) that provides a smooth change in
air flow direction for the surface flow B as it transitions from
the first portion 25 to the groove 15 so that the surface flow B
flows over the groove 15 and onto the boss 13 (see FIG. 3a). As
mentioned previously, the boss 13, the groove 15, and the inner
wall 26 (i.e. 25 and 27) can be formed by forging, machining, or
diecasting.
[0056] In FIGS. 5a and 5b, the vanes 21 can be inclined at angle
with respect to the axis Z-Z. In FIG. 5a, the vanes 21 are inclined
at an angle .beta. measured between a line 21c and the axis Z-Z.
The line 21c is measured along the primary slot P of the fins 23.
The inclination of the angle .beta. includes but is not limited to
a range from about 0 (zero) degrees to about 25.0 degrees. In
another embodiment of the present invention as illustrated in FIG.
5b, the angle at which the vanes 21 are inclined with respect to
the axis Z-Z includes a first angle .delta..sub.1 measured between
a line 21d and the axis Z-Z and a second angle .delta..sub.2
measured between a line 21e and the axis Z-Z. The first angle
.delta..sub.1 is measured along the smooth radially outward portion
37 of the fins 23. The inclination of the first angle .delta..sub.1
includes but is not limited to a range from about 0 (zero) degrees
to about 25.0 degrees. The second angle .delta..sub.2 is measured
along the the smooth curved portion 33 of the fins 23. The
inclination of the second angle .delta..sub.2 includes but is not
limited to a range from about 5.0 degrees to about 18.0 degrees.
Because the fins 23 are defined by the vanes 21, the fins 23 and
the vanes 21 are inclined at the angles (.beta., .delta..sub.1, and
.delta..sub.2) as described above.
[0057] In one embodiment of the present invention as illustrated in
FIG. 6, the vanes 21 have a tangential orientation with respect to
a circle C.sub.t (shown in dashed line) centered about the axis Z-Z
(shown as a "+") and having a predetermined diameter. In FIG. 6, an
example of the tangential orientation of the vanes 21 is
illustrated by a plurality of the vanes 21 having tangent lines t
drawn through their primary slots P and tangentially crossing a
perimeter of the circle C.sub.t. A line M through the axis Z-Z and
a parallel line N that also is tangential to the circle C.sub.t
define a radius R therebetween and the predetermined diameter of
the circle C.sub.t is two times the radius R (that is:
C.sub.t=2*R). The predetermined diameter includes but is not
limited to a range from about 3.0 millimeters to about 12.0
millimeters.
[0058] In FIGS. 5a, 5b, and 6, at least a portion of the top face
29 of the vanes 21 includes a substantially planar portion 29a
(shown as a dashed line). Preferably the substantially planar
portion 29a covers the entirety of the top face 29 as illustrated
in FIG. 6. One advantage of the substantially planar portion 29a of
the top face 29 is that a fan can be mounted on the substantially
planar portion 29a.
[0059] In FIG. 7, a fan 70 is positioned to be mounted on the
substantially planar portion 29a of the top face 29. The fan 70
generates an air flow (see reference letter F in FIG. 3a) into the
chamber 30 of the cooling device 10 in a direction indicated by
dashed arrow af. A shroud 73 houses a rotor hub 79 having a
plurality of fan blades 77. The rotor hub 79 is rotatably mounted
on a stator 71 and the fan blades 77 rotate in a direction
indicated by arrow rr. Several holes 75 through the shroud 77 are
adapted to receive a fastener 89.
[0060] A mounting ring 80 including a frame 81 and several mounting
fixtures 83 is abutted against a surface 37a of the smooth radially
outward portion 37. The diameter of the smooth radially outward
portion 37 at the surface 37a is greater than an inside diameter of
the frame 81 of the mounting ring 80 so that the frame 81 can be
urged into snug contact with the smooth radially outward portion 37
without sliding off of the vanes and fins (21, 23). The only way to
slide the mounting ring 80 off of the vanes and fins (21, 23) is in
the direction of the base 17 because the diameter of the vanes and
fins (21, 23) narrows in that direction. The mounting fixtures 83
receive the fastener 89 and optionally an additional fastener 87
such that the fan 70 is firmly connected with the top face 29 as
illustrated in FIG. 8. The fasteners (87, 89) can be a nut and bolt
as shown or another type of fastener. Preferably, a rotational axis
B-B of the fan 70 is colinear with the axis Z-Z of the cooling
device 10 when the fan 70 is connected with the mounting ring 80.
Examples of suitable materials for the mounting ring 80 include but
are not limited to metals, plastics, or ceramics. The mounting ring
80 can be produced by machining, casting, molding, and pressure
diecasting.
[0061] Although the previous discussion has focused on fasteners as
one means of connecting the mounting ring 80 with the fan 70, the
present invention is not to be construed as being limited to
fasteners only. For instance, a latch on the fan could mate with a
complementary latching profile on the mounting ring 80. Because the
mounting ring 80 can be formed by an injection molding process,
many possibilities exist for effectuating the mounting of the fan
70 to the mounting ring 80 and fasteners are an example of one of
those many possibilities.
[0062] In FIG. 8, the fan 70 is shown mounted on the substantially
planar portion 29a of the top face 29. For purposes of
illustration, only one set of fasteners (87, 89) are shown
installed through the holes 75 and the mounting fixtures 83. A
power lead 72 of the fan 70 is positioned so that it is not
necessary for the power lead 72 to be routed through or to come
into contact with the vanes or fins (21, 23). Although shown with
only two wires (+ and -) the power lead 72 can include additional
wires such as one or more additional wires for communicating with a
circuit that controls the fan 70 (e.g turning fan 70 on or off, or
controlling fan speed) or for determining if the fan 70 is
operating properly.
[0063] Although only one fan 70 is shown in FIGS. 7 and 8, two or
more fans 70 can be stacked one upon the other with the holes 75
aligned so that a longer fastener 89 can be inserted through the
holes 75 an into the mounting fixtures 83 of the mounting ring 80.
Therefore, another advantage of the cooling device 10 of the
present invention is that a plurality of fans can be used to
generate the air flow F into the chamber 30. The use of more than
one fan 70 allows for redundant cooling if one or more fans should
fail. In contrast, prior fan assisted heat sinks in which the fan
is mounted in a cavity formed by the fins, it is very difficult to
mount more than one fan in the cavity. Moreover, because the fan 70
is not mounted in the chamber 30, the risks associated with routing
the power lead 72 through the vanes 21 is eliminated because the
fan 70 is mounted on the top face 29. An additional advantage to
mounting the fan 70 on the top face is that if one or more of the
vanes and fins (21, 23) are damaged, the blades 77 will not come
into contact with a damaged vane or fin (21, 23); therefore,
potential damage to the blades 77 or the fan 70 is eliminated. In
FIG. 3b, a notch 41 can be formed in the fins 23. The notch 41 can
have a shape the complements an indexing tab (not shown) on the
shroud 73 so that when the fan 70 is mounted on the top face 29 the
indexing tab mates with the notch 41. The notch 41 can be used to
ensure proper orientation of the fan 70 with respect to the cooling
device 10 and/or to prevent relative movement between the shroud 73
and the cooling device 10.
[0064] In FIG. 9, the tangential orientation of the vanes 21 can be
determined by two factors (note: the base 17 has been omitted for
purposes of illustration) A first factor is a height h.sub.1 from
the top of the boss 13 to the top face 29. For example, when the
height h.sub.1 is about 7.5 millimeters, the vanes 21 can be
tangential to the circle C.sub.t having a diameter of about 6.5
millimeters. On the other hand, a second factor is a height h.sub.2
from the top of the boss 13 to a bottom 76 of the fan blades 77.
For instance, the diameter of the circle C.sub.t can be from about
3.0 millimeters to about 12.0 millimeters when the height h.sub.2
varies from about 2.0 millimeters to about 8.5 millimeters. The
above are examples only and the heights (h.sub.1, h.sub.2) are not
to be construed as being limited to the ranges set forth above.
[0065] The angle (.beta., .delta..sub.1 and .delta..sub.2) at which
the vanes 21 are inclined relative to the axis Z-Z as described
above can be set to substantially match or closely approximate a
pitch angle .theta. of the fan blades 77 as illustrated in FIG. 9.
On the other hand, the angles (.beta., .delta..sub.1, and
.delta..sub.2) can be set so that they are within a predetermined
range of the pitch angle .theta.. For example, the pitch angle
.theta. can be about 15.0 degrees and the angle .beta. can be about
17.0 degrees or the pitch angle .theta. can be about 12.0 degrees
and the angle .delta..sub.1 can be about 10.0 degrees and the angle
.delta..sub.2 can be about 8.0 degrees.
[0066] Another advantage of the cooling device 10 of the present
invention is that the aforementioned tangential orientation and
inclination of the vanes 21 and the aerodynamically profiled first
and second portions (25, 27) of the inner wall 26 provide a low
resistance path to the air flow F thereby reducing airflow shock
noise. Additionally, because of the low resistance path, the fan 70
can be a lower RPM fan which produces lower noise levels and can be
operated on less power than a higher RPM fan.
[0067] The cross-sectional view of the cooling device 10 in FIG. 9
(sans the base 17) also depicts radiuses for the arcuate shapes of
the boss 13, the groove 15, the second portion 27, the first
arcuate surface profile 21a, and the second arcuate surface profile
23a.
[0068] The arcuate profile of the boss 13 can have a radius r.sub.B
that is dependent in part on a desired thermal mass for the boss
13. For instance, for a thermal mass of about 50.0 grams, the
radius r.sub.B for the boss 13 is about 15.0 millimeters.
Similarly, the arcuate profile of the groove 15 has a radius
r.sub.G of about 2.5 millimeters. The actual values for r.sub.B and
r.sub.G will be application dependent and the above values are
examples only. The present invention is not to be construed as
being limited to the values set forth above.
[0069] Furthermore, the arcuate surface profiles for the first and
second arcuate surface profiles (21a, 23a) have a radius of r.sub.V
and r.sub.F respectively. For example, the radius r.sub.V can be
from about 38.0 millimeters to about 45.0 millimeters and the
radius r.sub.F can be from about 31.0 millimeters to about 38.0
millimeters. The second portion 27 of the inner wall 26 has a
radius r.sub.C. The radius r.sub.C can be about 20.0 millimeters,
for example. The actual values for r.sub.V, r.sub.F and r.sub.G
will be application dependent and the above values are examples
only. The present invention is not to be construed as being limited
to the values set forth above.
[0070] The above mentioned radiuses can be determined by a
machining process used to form the cooling device 10. Reference
points for the radiuses need not be relative to a point on the
cooling device 10. The radiuses r.sub.B, r.sub.G and r.sub.C can be
formed by a forging process. They can also be machined or produced
using a diecasting process. The radiuses r.sub.V and r.sub.F can be
formed by machining after forging the cooling device 10 from a
blank or material.
[0071] In one embodiment of the present invention as illustrated in
FIG. 10, a fan 74 without a shroud (i.e. it lacks the shroud 73 of
FIGS. 7 and 8) is positioned over the top face 29 of the cooling
device 10 by a space frame 90. A stator 71 of the fan 74 is
connected with the space frame 90 and a plurality of arms 91 span
the width of the top face 29 and fingers 93 at the ends of the arms
91 clamp the space frame 90 to the cooling device 10 approximately
at the surface 37a of the smooth radially outward portion 37.
Consequently, a hub 79 and blades 77 of the fan 74 are positioned
over the chamber 30 so that an air flow from the fan 74 can enter
the chamber 30 as was described above. Moreover, power leads 72
from the fan 74 can be routed away from the fins and vanes (21, 23)
of the cooling device 10 and away from the fan blades 77.
[0072] The space frame 90 can be integrally formed with the stator
71 or the space frame 90 can be made from a metal or plastic
material, preferably plastic because it is electrically
non-conductive.
[0073] In another embodiment of the present invention as
illustrated in FIGS. 1, 4, and 11, the base 17 of the cooling
device 10 includes at least two projections 22 that extend outward
of the mounting surface 19. A thermal interface material 24 is
positioned between the projections 22 and is in contact with the
mounting surface 19. The projections 22 protect the thermal
interface material 25 from damage when the base 17 is in contact
with a component 50 or from damage during manufacturing, transit,
and handling. The thermal interface material 24 is in contact with
a component face 51 of the component 50 and the thermal interface
material 24 provides a thermally conductive path for waste heat
from the component face 51 to be communicated through the base 17
and into the heat mass 11. The projections 22 prevent the thermal
interface material 24 from being crushed, deformed, or otherwise
damaged by mounting the cooling device 10 on the component 50
and/or during manufacturing, transit, and handling. The projections
22 can extend outward of the mounting surface 19 by a distance
d.sub.P (see FIG. 1) from about 0.2 millimeters to about 1.0
millimeters. Preferably, the mounting surface 19 is a substantially
planar surface (i.e. it is substantially flat) and the mounting
surface 19 is substantially perpendicular to the axis Z-Z (i.e.
about 90.0 degrees, see angle .alpha. in FIG. 10).
[0074] Additionally, the thermal interface material 24 seals micro
voids (i.e. gaps) between the mounting surface 19 and the component
face 51 thereby enhancing thermal transfer from the component 50 to
the cooling device10. Suitable materials for the thermal interface
material 24 include but are not limited to a thermally conductive
paste, a thermally conductive grease, silicone, paraffin, a phase
transition material, graphite, a coated aluminum foil, and carbon
fiber. The thermal interface material 24 can be screen printed or
pasted to the mounting surface 19, for example.
[0075] In FIGS. 4 and 12a through 12d, the base 17 can include a
cylindrical neck 18 that is inset (see reference numeral 18a) from
the base 17 to define an attachment groove 18g between the base 17
and the heat mass 11. The base 17 can also include a pair of flats
28 that are positioned substantially perpendicular to the mounting
surface 19 and positioned in parallel opposition to each other. In
FIGS. 12a and 12b, the base 17 can have a cylindrical or elliptical
shape 55 with the flats 28 formed on opposing sides of the base 17
(see FIG. 12b). The aforementioned projections 22 can have an
arcuate shape that complements the cylindrical shape 55; however,
the projections 22 can have any shape including a linear shape. The
flats 28 can be formed using conventional machining processes such
as milling, for example. The projections 22 can be positioned
proximate the edges of the base 17 as shown in FIGS. 12b and 12d,
or the projections 22 can be inset (see dashed arrows i) from the
edges as illustrated in FIG. 12b and FIG. 1.
[0076] FIG. 12d is an enlarged view of a section L-L of FIG. 12c
illustrating the base 17, cylindrical neck 18, and the projections
22. The projections 22 extend slightly outward of the mounting
surface 19; however, the distance d.sub.P for the projections 22
will depend on factors including the thickness of the thermal
interface material 24.
[0077] In FIG. 13, a system for dissipating heat 100 includes the
cooling device 10 as described above, a fan 70 connected with the
top face 29 as described above, a component 50 to be cooled by the
cooling device 10, and a base mount 300. A component face 51 of the
component 50 is in contact with the mounting surface 19, or as
described above in reference to FIG. 11, a thermal interface
material 24 may be positioned intermediate between the component
face 51 and the mounting surface 19. In either case, waste heat is
thermally communicated through the component face 51 into the base
17 either by direct contact between the component face 51 and the
mounting surface 19 or via the thermal interface material 24. The
base mount 300 urges the mounting surface 19 and the component face
51 into contact with each other so that heat from the component is
thermally communicated into the cooling device 10.
[0078] In one embodiment of the present invention, the mounting
surface 19 of the cooling device 10 includes the projections 22
that extend outward of the mounting surface 19 and the thermal
interface material 24 is positioned intermediate between the
projections 22 as described above in reference to FIG. 11.
[0079] In another embodiment of the present invention, the base 17
of the cooling device 10 includes the cylindrical neck 18 that is
inset 18a from the base 17 to define the attachment groove 18g and
the flats 28 as was previously described in reference to FIGS. 4
and 12 a through 12d above. In yet another embodiment of the
present invention, the mounting surface 19 includes the projections
22 and the thermal interface material 24 as described above.
[0080] In another embodiment of the present invention, the
component 50 is carried by a support unit 99. The support unit
includes but is not limited to a socket, a substrate, and a PC
board. The socket can be mounted to a PC board in a manner that is
well understood in the electronics art. For instance the component
can be a micro processor that is inserted into a socket that is
solder onto a PC board. The base mount 300 is removably connected
with the support unit 99. On the other hand, the support unit can
be a PC board on which the component 50 is soldered or otherwise
electrically connected with. Although the present invention has
described the cooling device 10 in terms of its usefulness in
dissipating waste heat from electronic components, the cooling
device 10 and the system 100 are not to be construed as being
limited to cooling electronic devices exclusively. Accordingly, the
component 50 can be any heat generating device from which it is
desirable to remove heat. To that end, the support unit 99 need not
be a PC board or a socket. The support unit 99 can be a substrate
that carries the component 50. The component 50 may or may not be
in electrical communication with the substrate.
[0081] In FIG. 13, the base mount 300 is a base plate such as the
type used for mounting a heat sink to a PC board. A plurality of
holes 300a formed in the base mount 300 and a plurality of holes
99a formed in the support unit 99 receive fasteners (87, 89) that
removably connect the base mount 300 with the support unit 99.
Although a nut and bolt are shown, other fasteners and other
fastening methods can be used to removably connect the base mount
300 with the support unit 99.
[0082] In FIG. 14, a system 200 includes the cooling device 10, the
component 50, the fan 70, and the support unit 99 that carries the
component 50. The base mount 300 is a spring clip including a
handle 122 for latching and unlatching the spring clip from the
support unit 99 that carries the component 50. In FIG. 14, the
support unit 99 is a socket such as a zero insertion force socket,
for example. The spring clip includes a hinge end 116 and a latch
117. The hinge end 116 includes a hinge 118 that can be removably
hinged on a tab 94 connected with the support unit 99 and the latch
end 117 includes a latch 131 that can be removably latched onto a
tab 92 also connected with the support unit 99. The support unit 99
can be mounted on a PC board 101.
[0083] The spring clip includes a pair of ribs (see reference
numerals 114, 115 in FIGS. 15b and 15c) that include latch arms 137
and hinge arms 136 that have a vertex V at a rocking axis Y-Y. The
rocking axis Y-Y is colinear with a load axis B-B of the spring
clip. The hinge arm 136 has a portion 136a that is inclined at an
angle relative to a base plane (not shown) through the vertex V and
the latch arm 137 has two portions 137a and 137b that are also
inclined at an angle with respect to the vertex. Those angles
result in a load L being applied substantially along the load axis
B-B when the spring clip is latched as shown in FIG. 14. The load L
is also substantially colinear with the axis Z-Z and with a
component axis C-C of the component 50. Preferably the component
axis C-C is at a center of the component 50 so that the load L acts
substantially at the center of the component.
[0084] FIGS. 15a through 15c illustrate insertion of the cooling
device 10 into the spring clip which is denoted as reference
numeral 300. In FIGS. 15a and 15b the flats 28 of the cooling
device 10 are aligned with inside edges 132 of the ribs (114, 115)
and then the base 17 is inserted through an opening 133 between the
ribs (114, 115) until the attachment groove 18g of the cylindrical
neck 18 is between the ribs (114, 115). Next, the cooling device 10
is rotated as illustrated by angle .OMEGA. in FIG. 15c. For
example, the angle .OMEGA. can be about 90.0 degrees. Now, the
flats 28 are substantially perpendicular to the ribs (114, 115) and
are positioned below the ribs (114, 115) so that the rocking axis
Y-Y rests on an upper surface 18e of the base 17. Next, a locking
rib 128 is inserted into a set of notches (not shown) on the ribs
(114, 115) of the hinge end 116. After insertion, the locking rib
is substantially parallel to the rocking axis Y-Y and the locking
rib 128 rests against one of the flats 28 so that the cooling
device 10 cannot be rotated out of the spring clip 300.
[0085] Finally, the hinge 118 is inserted over the tab 94 and the
latch 131 is latched onto the tab 92 of the support unit 99 thereby
placing the mounting surface 19 in contact with the component face
51. With the spring clip 300 latched to the support unit 99, the
load L exerted by the spring clip 300 acts along the load axis B-B.
Preferably, the load axis B-B, the component axis C-C, and the axis
Z-Z of the cooling device 10 are colinear with one another.
[0086] Ideally, the component face 51 and the mounting surface 19
are substantially planar (i.e they are flat) and the component 50
is mounted substantially level in the support unit 99; however, due
to manufacturing processes there can be deviations from a
substantially planar surface, the component 50 may not be level,
and thermally induced dimensional changes in any of the
aforementioned elements of the system 200 can cause deviations from
the ideal. The ribs (114, 115) at the rocking axis have an arcuate
surface shape that allows the cooling device 10 some freedom of
movement while exerting the load L along the load axis B-B.
Therefor, the aforementioned deviations are compensated for by not
rigidly fixing the cooling device 10 within the spring clip 300.
Additionally, the ribs (114, 115) can include one or more embossed
features 129 that also allow the cooling device some freedom of
movement within the spring clip 300. The embossed features 129 are
urged into contact with the upper surface 18e when the spring clip
300 is latched to the support unit 99.
[0087] Removal of the cooling device 10 is the opposite of
insertion. The spring clip 300 is unlatched from the support unit
99 by using the handle 122 to unlatch the latch 131 from the tab 92
and pivoting the spring clip 300 to disconnect the hinge 118 from
the tab 94. Next, the locking rib 128 is removed from the spring
clip 300 freeing the base 17 to rotate. The base 17 is then rotated
until the flats 28 are substantially parallel to the inside edges
132 and then the base 17 is pulled out of the opening 133.
[0088] The spring clip 300 is described in applicants Pending U.S.
Utility Patent Application entitled "SPRING CLIP FOR A COOLING
DEVICE", HP Attorney Docket Number 10013183-1, filed on Friday,
Jul. 27, 2001 and assigned to the assignee of the present
application. The above mentioned Pending application is
incorporated herein by reference as though set forth in its
entirety.
[0089] The systems (100, 200) can include the projections 22 on the
mounting surface 19 and the thermal interface material 24 as was
described above in reference to FIG. 11. The thermal interface
material 24 can be connected with the mounting surface 19, the
component face 51, or both prior to latching the spring clip 300 to
the support unit 99 or prior to mounting the base plate of FIG. 13
to the support unit 99.
[0090] In one embodiment of the present invention, the systems
(100, 200) can include a shroudless fan 74 as was described above
in reference to FIG. 10. The fan 74 includes the space frame 90 for
supporting the fan 74 and for positioning the fan 74 adjacent to
the top face 29 and over the chamber 30 so that the air flow af
enters the chamber 30. As previously mentioned, the space frame 90
includes a plurality of arms 91 that span the width of the top face
29 and fingers 93 on the arms 91 clamp the space frame 90 to the
smooth radially outward portion 37 of the outer wall 32.
[0091] Preferably, the heat mass 11, the base 17, and the vanes 21
are homogeneously formed. An extrusion process can be used to
homogeneously form the heat mass 11, the base 17, and the vanes 21.
The cooling device 10 can be made from a variety of thermally
conductive materials including but not limited to copper,
electrolytic copper, aluminum, and alloys of aluminum and copper,
ceramics, and silicon (Si) substrates. An exemplary material for
the cooling device 10 is aluminum 1060 or aluminum 6063.
[0092] The cooling device 10 can be manufactured by a variety of
processes including but not limited to those listed below. First,
the cooling device 10 can completely machining from an extruded bar
stock. Second, a diecasting, forging, or pressing process can be
used to form either one or both of the internal and external
features (26, 32) of the cooling device 10, followed by a machining
process to form the base 17, the mounting surface 19, the
projections 22, the cylindrical neck 18, and the attachment groove
18g. Next cutting wheels can be used to form the primary P and
secondary S slots for the vanes 21 and the fins 23 respectively,
followed by deburring and degreasing. Third, impact forging the
complete cooling device 10 including the vanes 21 and fins 23.
Fourth, pressure diecasting the complete cooling device 10
including the vanes 21 and fins 23.
[0093] An exemplary model of the cooling device 10 was created with
a diameter of 65 mm at the top face 29 and a diameter of 50 mm at
the bottom surface 11 a of the heat mass 11. The base 17 had a
diameter of 40 mm and height of 6.5 mm from the bottom surface 1a.
The cooling device 10 had a total height from the mounting surface
19 to the top face 29 of about 33 mm. The heat mass 11 had a total
height of about 22 mm from the mounting surface 19 to a top of the
boss 13. The smooth curved portion 33 had a radius of about 33 mm
and the draft portion 35 had a diameter of about 63 mm. A Delta
fan, model number EFB0612HA, and having dimensions of 60
mm.times.60 mm.times.10 mm in length, breadth, and height was
mounted to the cooling device 10 as illustrated in FIG. 14. The
cooling device 10 was then mounted on a processor carried by a PGA
370 connector that was soldered onto a mother board. The processor
had a top surface of approximately 9 mm.times.11 mm and a thermal
output of 36 watts. The cooling device 10 as described in this
paragraph was capable of maintaining the case temperature of the
processor at 38.0 degrees Celsius at an ambient temperature of 25.0
degrees Celsius. Based on the above temperatures, a temperature
difference of 13.0 degrees Celsius for 36 watts of thermal power
results in an estimated thermal resistance for the cooling device
10 of 0.3611 degrees Celsius per watt (13.0 degrees Celsius/36
watts=0.3611).
[0094] Although several embodiments of the present invention have
been disclosed and illustrated, the invention is not limited to the
specific forms or arrangements of parts so described and
illustrated. The invention is only limited by the claims.
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