U.S. patent application number 09/778312 was filed with the patent office on 2001-08-16 for heat sink-equipped cooling apparatus.
Invention is credited to Maruyama, Haruhisa, Ogawara, Toshiki, Sasa, Noriyasu, Watanabe, Michinori.
Application Number | 20010014011 09/778312 |
Document ID | / |
Family ID | 26587375 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010014011 |
Kind Code |
A1 |
Sasa, Noriyasu ; et
al. |
August 16, 2001 |
Heat sink-equipped cooling apparatus
Abstract
A heat sink-equipped cooling apparatus capable of exhibiting
increased cooling performance and durability and being reduced in
dimensions in a radial direction thereof. A heat sink includes a
radiation fin unit including a plurality of radiation fins arranged
so as to surround a virtual central line while keeping a center
thereof aligned with the central line. A cooling fan includes an
impeller including a plurality of blades and rotated through a
motor. The cooling fan is mounted on the heat sink in such a manner
that the impeller is positioned above the radiation fin unit of the
heat sink. The radiation fins each are inclined with respect to a
virtual vertical plane so as to form a predetermined inclination
angle .theta. therebetween.
Inventors: |
Sasa, Noriyasu; (Hokkaido,
JP) ; Ogawara, Toshiki; (Tokyo, JP) ;
Watanabe, Michinori; (Tokyo, JP) ; Maruyama,
Haruhisa; (Tokyo, JP) |
Correspondence
Address: |
RANKIN, HILL, PORTER & CLARK, LLP
700 HUNTINGTON BUILDING
925 EUCLID AVENUE
CLEVELAND
OH
44115-1405
US
|
Family ID: |
26587375 |
Appl. No.: |
09/778312 |
Filed: |
February 7, 2001 |
Current U.S.
Class: |
361/704 ;
257/E23.099; 257/E23.103 |
Current CPC
Class: |
H01L 2924/0002 20130101;
H01L 23/3672 20130101; H01L 2924/0002 20130101; H01L 2924/00
20130101; H01L 23/467 20130101 |
Class at
Publication: |
361/704 |
International
Class: |
H05K 007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2000 |
JP |
69431/2000 |
Feb 6, 2001 |
JP |
30159/2001 |
Claims
What is claimed is:
1. A cooling apparatus comprising: a heat sink for dissipating heat
generated from a heat source; said heat sink including a base plate
increased in thermal conductivity and including a front surface and
a rear surface with which the heat source is contacted, a virtual
central line defined so as to extend in a direction perpendicular
to said front surface of said base plate, a plurality of virtual
vertical planes defined so as to extend in both a radial direction
from said central line and a vertical direction perpendicular to
said front surface of said base plate and be spaced from each other
at equal intervals in a circumferential direction of a virtual
circle defined about said central line, and a radiation fin unit
mounted on said front surface of said base plate in a manner to be
heat-transferable and including a plurality of radiation fins
arranged so as to surround said central line while aligning said
central line with a center in arrangement of said radiation fins;
and a cooling fan including an impeller which includes a plurality
of blades and is rotated by a motor and mounted on said heat sink
so that said impeller is positioned above said radiation fin unit;
said radiation fins each including a lower edge positioned on a
side of said base plate, an upper edge positioned opposite to said
lower edge, and a radiation surface positioned between said lower
edge and said upper edge; said radiation fins each being fixedly
mounted on said front surface of said base plate so as to be
positioned on an intersection line between said virtual vertical
plane corresponding to each of said lower edges and said front
surface of said base plate; said radiation fins each being arranged
while being inclined in an identical direction with respect to said
virtual vertical plane so that an inclination angle .theta. of
predetermined degrees between said radiation surface of said
radiation fin and said virtual vertical plane may be defined; said
radiation fin unit and cooling fan being arranged in positional
relationship which permits each of said blades of said cooling fan
and said upper edge of each of said radiation fins to be opposite
to each other; said cooling fan being arranged so as to permit
cooling air to be fed to said radiation fins of said radiation fin
unit.
2. A cooling apparatus as defined in claim 1, wherein said virtual
vertical planes are defined so as to be spaced from each other at
equal intervals in said circumferential direction of said virtual
circle.
3. A cooling apparatus as defined in claim 1, wherein said
radiation fin unit is formed by subjecting a single metal plate
increased in thermal conductivity to bending.
4. A cooling apparatus as defined in claim 1, wherein said
radiation fin unit includes a single fan mounting metal plate
joined to said front surface of said base plate; said radiation
fins each are formed of a flat metal plate; and said radiation fins
each are fixed at said lower edge thereof on said fin mounting
metal plate.
5. A cooling apparatus as defined in claim 4, wherein said
radiation fins each are integrally mounted at said lower edge
thereof with a flange for fixing; said flange being arranged so as
to extend along a surface of said fin mounting metal plate and
fixed on said surface of said fin mounting metal plate.
6. A cooling apparatus as defined in claim 1, wherein said fin
mounting metal plate is formed with a plurality of slits in a
manner to radially extend from said central line and be spaced from
each other at predetermined intervals in said circumferential
direction; said radiation fins each are integrally formed at said
lower edge thereof with a fit projection which is fitted in each of
said slits; and said radiation fins each are joined to said fin
mounting metal plate while keeping said fit projection fitted in
each of said slits.
7. A cooling apparatus as defined in claim 1, wherein said base
plate is formed with a plurality of slits in a manner to radially
extend from said central line and be spaced from each other at
predetermined intervals in said circumferential direction; said
radiation fins each are integrally formed at said lower edge
thereof with a fit projection which is fitted in each of said
slits; and said radiation fins each are joined to said fin mounting
metal plate while keeping said fit projection fitted in each of
said slits.
8. A cooling apparatus as defined in claim 1, wherein said
radiation fins each are integrally provided at said lower edge
thereof with a flange for fixing; said flange being arranged so as
to extend along said front surface of said base plate and mounted
on said front surface of said base plate.
9. A cooling apparatus as defined in claim 1, wherein said
radiation fin unit is provided at a central portion thereof with a
space of a frust conical configuration while having a center
positioned on a central line of said radiation fin unit and being
gradually reduced in diameter toward said base plate.
10. A cooling apparatus as defined in claim 1, wherein radiation
fins each are formed into an identical shape.
11. A cooling apparatus as defined in claim 10, wherein said fin
mounting metal plate and radiation fins each are made of a material
selected from the group consisting of copper and copper alloy.
12. A cooling apparatus as defined in claim 1, wherein said
inclination angle .theta. is less than 45 degrees.
13. A cooling apparatus as defined in claim 12, wherein said
inclination angle .theta. is less than 45 degrees and more than 15
degrees.
14. A cooling apparatus as defined in claim 1, wherein said blades
of said cooling fan are inclined in a direction identical with a
direction in which said radiation fins are inclined; and said
cooling fan rotates said impeller in the direction in which said
radiation fins are inclined.
15. A cooling apparatus as defined in claim 1 or 14, wherein said
air blown against said radiation fin unit from said cooling fan is
permitted to enter a gap between each adjacent two of said
radiation fins through an opening defined between the upper edges
of each adjacent two of said radiation fins and then be radially
outwardly discharged from said radiation fin unit through said
gap.
16. A cooling apparatus as defined in claim 1, wherein said cooling
fan includes a casing; and said motor includes a housing; said
casing of said cooling fan including a casing body provided with an
air duct in a manner to surround at least a part of a periphery of
said impeller, a plurality of webs for supporting said housing of
said motor on said casing body, and a plurality of pillars each
mounted at one end thereof on said casing body and held at the
other end thereof on said base plate; and said base plate is
provided thereon with a plurality of holding portions in each of
which each of said pillars is held at the other end thereof.
17. A cooling apparatus comprising: a heat sink for dissipating
heat generated from a heat source; said heat sink including a
heat-transfer base plate and including a front surface and a rear
surface with which the heat source is contacted, a virtual central
line defined so as to extend in a direction perpendicular to said
front surface of said base plate, a plurality of virtual vertical
planes defined so as to extend in both a radial direction from said
central line and a vertical direction perpendicular to said front
surface of said base plate and be spaced from each other at equal
intervals in a circumferential direction of a virtual circle
defined about said central line, and a radiation fin unit mounted
on said front surface of said base plate in a manner to be
heat-transferable and including a plurality of radiation fins
arranged so as to surround said central line while aligning said
central line with a center in arrangement of said radiation fins;
said radiation fins each including a lower edge positioned on a
side of said base plate, an upper edge positioned opposite to said
lower edge, and a radiation surface positioned between said lower
edge and said upper edge; said radiation fins each being fixedly
mounted on said front surface of said base plate so as to be
positioned on an intersection line between said virtual vertical
plane corresponding to each of said lower edges and said front
surface of said base plate; said radiation fins each being arranged
while being inclined in an identical direction with said virtual
vertical plane so that an inclination angle .theta. of
predetermined degrees between said radiation surface of said
radiation fin and said virtual vertical plane may be defined.
18. A cooling apparatus comprising: a heat sink for dissipating
heat generated from a heat source; said heat sink including a base
plate increased in thermal conductivity and including a front
surface and a rear surface with which the heat source is contacted,
a virtual central line defined so as to extend in a direction
perpendicular to said front surface of said base plate, a plurality
of virtual vertical planes defined so as to extend in both a radial
direction from said central line and a vertical direction
perpendicular to said front surface of said base plate and be
spaced from each other at equal intervals in a circumferential
direction of a virtual circle defined about said central line, and
a radiation fin unit mounted on said front surface of said base
plate in a manner to be heat-transferable and including a plurality
of radiation fins arranged so as to surround said central line
while aligning said central line with a center in arrangement of
said radiation fins; and a cooling fan including an impeller which
includes a plurality of blades and is rotated by a motor and
mounted on said heat sink so that said impeller is positioned above
said radiation fin unit; said radiation fins each including a lower
edge positioned on a side of said base plate, an upper edge
positioned opposite to said lower edge, and a radiation surface
positioned between said lower edge and said upper edge; said
radiation fins each being fixedly mounted on said front surface of
said base plate so as to be positioned on an intersection line
between said virtual vertical plane corresponding to each of said
lower edges and said front surface of said base plate; said
radiation fins each being arranged while being inclined in an
identical direction with respect to said virtual vertical plane so
that an inclination angle .theta. of predetermined degrees between
said radiation surface of said radiation fin and said virtual
vertical plane may be defined; said radiation fin unit and cooling
fan being arranged in positional relationship which permits each of
said blades of said cooling fan and said upper edge of each of said
radiation fins to be opposite to each other; said radiation surface
of each of said radiation fins and said virtual vertical plane
being arranged with an angle of 90.degree.-.lambda. being defined
therebetween, wherein .lambda. is more than 45 degrees and less
than 85 degrees (45.degree.<.lambda.<85.degree.); said
radiation fins and base plate being formed so that a ratio C
between a total radiation area F of said radiation fins and an area
S of said base plate (C=F/S) is more than 10 and less than 40
(10<C<40); said cooling fan being arranged so as to permit
cooling air to be fed to said radiation fins of said radiation fin
unit.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a cooling apparatus equipped with
a heat sink for dissipating heat emitted from a heat source, and
more particularly to a heat sink-equipped cooling apparatus
suitable for use for cooling an electronic component such as a CPU
or the like.
[0002] Heat generated or emitted from an electronic component such
as a CPU or the like used in a computer is progressively increased
with an increase in performance of the electronic component.
Japanese Utility Model Publication No. 15982/1991 discloses a
cooling apparatus which is so constructed that a cooling fan is
arranged above a heat sink having a plurality of radiation fins
radially arranged on a front surface of a base plate thereof, to
thereby permit air discharged from the cooling fan to be fed to a
central region of the base plate and then outwardly exhausted
through the radiation fins. Another conventional cooling apparatus
is disclosed in U.S. Pat. No. 5,629,834 (corresponding to Japanese
Patent No. 2,765,801 and Japanese Patent Application Laid-Open
Publication No. 111302/1985) and U.S. Pat. No. 5,782,292
(corresponding to Japanese Patent Application Laid-Open Publication
No. 102566/1997, which includes a heat sink having a plurality of
radiation fins arranged in directions of flowing of air radially
discharged from an impeller of a fan. In the cooling apparatus
disclosed, the radiation fins are arranged so as to surround a part
of the impeller of the fan. A further conventional cooling
apparatus is disclosed in U.S. Pat. No. 5,785,116 (corres. to
Japanese Patent Application Laid-Open Publication No. 219478/1998),
which includes a heat sink having a plurality of radiation fins
arranged on a base plate thereof so as to surround an impeller of a
fan. The radiation fins are arranged in a manner to be inclined
with respect to a central line extending through a center of the
fan. In the cooling apparatus thus constructed, the heat sink
including the plural radiation fins is formed by subjecting a
cylindrical material to cutting which is carried out in a direction
inclined with respect to a central line of the cylindrical
material. Also, in the cooling apparatus, predetermined accurate
relationship must be established between an angle of the radiation
fins and an angle of the blades of the fan in order to permit the
cooling apparatus to exhibit satisfactory cooling performance.
Further, a motor of the fan is mounted on the heat sink.
[0003] The first and second conventional cooling apparatus
described above each are not suitable for use for cooling an
electronic component Increased in heat generation. The third
conventional cooling apparatus described above is suitable for
cooling an electronic component increased in heat generation as
compared with the first and second cooling apparatus. However, in
the third cooling apparatus, the heat sink is increased in
manufacturing cost and it is required to increase machining
accuracy. Also, the third apparatus, as described above, is so
constructed that the radiation fins are arranged so as to surround
the impeller of the fan. Such arrangement causes a size of the
cooling apparatus In a radial direction thereof to be significantly
increased. Further, mounting of the motor of the fan on the heart
sink in the third apparatus causes transmission of heat from the
heat sink to the motor, leading to a deterioration in durability of
the motor.
SUMMARY OF THE INVENTION
[0004] The present invention has been made in view of the foregoing
disadvantage of the prior art.
[0005] Accordingly, it is an object of the present invention to
provide a heat sink-equipped cooling apparatus which is capable of
exhibiting increased cooling performance and durability and
reducing a size thereof in a radial direction thereof.
[0006] It is another object of the present invention to provide a
heat sink-equipped cooling apparatus which is capable of being
reduced in manufacturing cost thereof.
[0007] It is a further object of the present invention to provide a
heat sink-equipped cooling apparatus which is capable of being
simplified in manufacturing thereof.
[0008] It is still another object of the present invention to
provide a heat sink-equipped cooling apparatus which is capable of
permitting the number of radiation fins arranged to be increased to
a degree sufficient to enhance cooling performance of the cooling
apparatus.
[0009] It is a still further object of the present invention to
provide a heat sink-equipped cooling apparatus which is capable of
permitting mass production thereof.
[0010] In accordance with the present invention, a heat
sink-equipped cooling apparatus is provided. The cooling apparatus
includes a heat sink for dissipating heat generated from a heat
source. The heat sink includes a base plate increased in thermal
conductivity and including a front surface and a rear surface with
which the heat source is contacted, a virtual central line defined
so as to extend in a direction perpendicular to the front surface
of the base plate, a plurality of virtual vertical planes defined
so as to extend in both a radial direction from the central line
and a vertical direction perpendicular to the front surface of the
base plate and be spaced from each other at equal intervals in a
circumferential direction of a virtual circle defined about the
central line, and a radiation fin unit mounted on the front surface
of the base plate in a manner to be heat-transferable and including
a plurality of radiation fins arranged so as to surround the
central line while aligning the central line with a center in
arrangement of the radiation fins. The cooling apparatus also
includes a cooling fan including an impeller which includes a
plurality of blades and is rotated by a motor and mounted on the
heat sink so that the impeller is positioned above the radiation
fin unit.
[0011] In the heat sink, the radiation fins each include a lower
edge positioned on a side of the base plate, an upper edge
positioned opposite to the lower edge, and a radiation surface
positioned between the lower edge and the upper edge. The radiation
fins each are fixedly mounted directly or indirectly on the front
surface of the base plate so as to be positioned on an intersection
line between the virtual vertical plane corresponding to each of
the lower edges and the front surface of the base plate. Also, the
radiation fins each are arranged while being inclined in an
identical direction with respect to the virtual vertical plane (or
toward one side in the circumferential direction of the virtual
circle) so that an inclination angle .theta. of predetermined
degrees between the radiation surface of the radiation fin and the
virtual vertical plane may be defined. The radiation fin unit and
cooling fan are arranged in positional relationship to each other
which permits each of the blades of the cooling fan and the upper
edge of each of the radiation fins to be opposite to each other.
The cooling fan is arranged so as to permit cooling air to be fed
to the radiation fins of the radiation fin unit. For this purpose,
the cooling fan may be operated so as to blow air against the
radiation fins. Alternatively, it may be operated so as to suck air
from a side of the radiation fins.
[0012] When the impeller of the cooling fan and the heat sink are
arranged in proximity to each other, air fed from the fan is
substantially kept from being fed to a portion of the heat sink
which is not opposite to the blades of the fan or a portion of the
heat sink which is opposite to a cup member on which the blades of
the impeller are fixed. Also, an air stream generated due to
rotation of the impeller is not permitted to flow in an axial
direction of the motor but is caused to flow in a direction of
rotation of the impeller. Thus, arrangement of the radiation fins
in a mere radial manner causes the radiation fins to act as flow
resistance, to thereby fall to permit an increase in cooling
performance of the cooling apparatus. This is also true of a
structure which is constructed so as to forcibly flow air in a
radial direction using an axial fan adapted to feed air in an axial
direction, to thereby flow the air around radiation fins positioned
outside an impeller, leading to cooling of the radiation fins. On
the contrary, the structure of the present invention that air fed
in the axial direction of the motor from the cooling fan is blown
against the radiation fins from above the radiation fin unit
enhances cooling performance of the cooling unit. Although this is
not clearly supported by any specific theory, it would be
considered that arrangement of the radiation fins employed in the
present invention reduces flow resistance to air discharged from
the cooling fan and produces a rapid air stream along the radiation
surface of each of the radiation fins, to thereby increase the
cooling performance. Thus, the cooling apparatus of the present
invention exhibits cooling performance at substantially the same
level as an expensive cooling apparatus conventionally used without
being increased in dimensions in a radial direction thereof and
ensuring satisfactory durability of the motor.
[0013] Ideally, the plural virtual vertical planes are defined so
as to be spaced from each other at equal intervals in the
circumferential direction of the virtual circle. This ensures
substantially uniform cooling of each of the radiation fins and
base plate, to thereby further enhance cooling efficiency of the
cooling apparatus.
[0014] The radiation fin unit may be formed by subjecting a single
metal plate increased in thermal conductivity to bending. This
reduces a manufacturing cost of the cooling apparatus and
facilitates manufacturing thereof.
[0015] In the present invention, the radiation fin unit may be
constructed so as to attain both simplified manufacturing of the
cooling apparatus and mass production thereof. More specifically, a
single fan mounting metal plate joined to the front surface of the
base plate is provided. The radiation fins each are formed of a
flat metal plate. Also, the radiation fins each are fixed at the
lower edge thereof on the fin mounting metal plate. The radiation
fins may be mounted on the fin mounting metal plate in any suitable
manner. For example, the radiation fins each are integrally mounted
at the lower edge thereof with a flange for fixing. The flange is
arranged so as to extend along a surface of the fin mounting metal
plate and fixed on the surface of the fin mounting metal plate. The
flange highly facilitates mounting of the radiation fins on the fin
mounting metal plate.
[0016] The present invention may be constructed so as to further
promote mass production of the cooling apparatus. For this purpose,
the fin mounting metal plate is formed with a plurality of slits in
a manner to radially extend from the central line and be spaced
from each other at predetermined intervals in the circumferential
direction. The radiation fins each are integrally formed at the
lower edge thereof with a fit projection which is fitted in each of
the slits. Also, the radiation fins each are joined to the fin
mounting metal plate while keeping the fit projection fitted in
each of the slits. This facilitates not only positioning of the
radiation fins on the fin mounting metal plate, but joining of the
radiation fins to the fin mounting metal plate while keeping the
radiation fins inclined.
[0017] Alternatively, the base plate may be formed with a plurality
of slits in a manner to radially extend from the central line and
be spaced from each other at predetermined intervals in the
circumferential direction. In this instance, the radiation fins
each are Integrally formed at the lower edge thereof with a fit
projection which is fitted in each of the slits. Also, the
radiation fins each are joined to the fin mounting metal plate
while keeping the fit projection fitted in each of the slits. This
reduces the number of parts required although it somewhat increases
a manufacturing cost of the apparatus. Alternatively, the radiation
fins each equipped with the fixing flange may be directly fixed on
the front surface of the base plate.
[0018] The radiation fins may be formed into the same
configuration. This leads to a reduction in manufacturing cost of
the radiation fins and therefore the cooling apparatus. In order to
cut out a number of radiation fins from a single large-sized metal
plate by punching with increased yields, the radiation fins each
preferably have a main portion formed into a substantially
rectangular shape. Thus, the radiation fin unit is permitted to be
provided at a central portion thereof with a space of a frust
conical configuration while having a center positioned on a central
line of the radiation fin unit and being gradually reduced in
diameter toward the base plate.
[0019] The inclination angle .theta. of the radiation fins is
basically varied depending on the number of radiation fins. An
increase in number of radiation fins leads to a reduction in
inclination angle, whereas a decrease in the number leads to an
increase in inclination angle. However, the inclination angle
.theta. is preferably less than 45 degrees. The inclination angle
of 45 degrees or more leads to a reduction in number of the
radiation fins, to thereby cause a deterioration in cooling
performance of the radiation fins. More preferably, the inclination
angle .theta. is less than 45 degrees and more than 15 degrees,
because it increases the number of radiation fins to a degree
sufficient to ensure satisfactory cooling performance of the
radiation fin unit.
[0020] The cooling fan is preferably constituted by a so-called
axial fan. The blades of the cooling fan are preferably inclined in
a direction identical with a direction in which the radiation fins
are inclined. In this instance, the cooling fan may be operated to
rotate the impeller in the direction in which the radiation fins
are inclined. This enhances cooling performance of the cooling
fan.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] These and other objects and many of the attendant advantages
of the present invention will be readily appreciated as the same
becomes better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings; wherein:
[0022] FIG. 1 is a schematic exploded perspective view showing a
first embodiment of a heat sink-equipped cooling apparatus
according to the present invention;
[0023] FIG. 2 is a perspective view showing a radiation fin unit
incorporated in the heat sink-equipped cooling apparatus of FIG.
1;
[0024] FIGS. 3 to 5 each are a schematic view showing manufacturing
of the radiation fin unit of FIG. 2 by way of example;
[0025] FIGS. 6 and 7 each are a schematic enlarged sectional view
showing an inclination angle of radiation fins of the radiation fin
unit of FIGS. 3 to 5;
[0026] FIG. 8 is a schematic sectional view showing relationship
between the radiation fins of FIGS. 6 and 7 and blades of an
impeller incorporated in the cooling apparatus of FIG. 1;
[0027] FIG. 9 is a plan view showing a second embodiment of a heat
sink-equipped cooling apparatus according to the present
invention;
[0028] FIG. 10 is a right side elevation view of the heat
sink-equipped cooling apparatus shown in FIG. 9;
[0029] FIG. 11 is a front elevation view of the heat sink-equipped
cooling apparatus shown in FIG. 9;
[0030] FIG. 12 is a schematic plan view showing a radiation fin
unit incorporated in the heat sink-equipped cooling apparatus of
FIG. 9;
[0031] FIG. 13 is a schematic front elevation view of the radiation
fin unit shown in FIG. 12;
[0032] FIG. 14 is a schematic plan view showing one of radiation
fins incorporated in the heat sink-equipped cooling apparatus shown
in FIG. 9;
[0033] FIG. 15 is a schematic plan view showing manufacturing of
the radiation fin unit of FIG. 12:
[0034] FIG. 16 is a schematic front elevation view showing
manufacturing of the radiation fin unit of FIG. 12;
[0035] FIG. 17 is a schematic plan view showing manufacturing of a
modification of the radiation fin unit shown in FIG. 12;
[0036] FIG. 18A is a schematic side elevation view showing another
modification of the radiation fin shown in FIG. 14;
[0037] FIG. 18B is a schematic front elevation view of the
radiation fin shown in FIG. 18A;
[0038] FIG. 19 is a schematic plan view showing manufacturing of
another modification of the radiation fin unit of FIG. 12:
[0039] FIG. 20 is a schematic front elevation view showing
manufacturing of another modification of the radiation fin unit of
FIG. 12;
[0040] FIG. 21 is a schematic plan view showing another still
another modification of the radiation fins shown in FIG. 14;
and
[0041] FIG. 22 is a schematic front elevation view showing
manufacturing of another modification of the radiation fin unit of
FIG. 12.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] Now, a heat sink-equipped cooling apparatus according to the
present invention will be described with reference to the
accompanying drawings.
[0043] Referring first to FIGS. 1 to 5, a first embodiment of a
heat sink-equipped cooling apparatus according to the present
invention is illustrated. A heat sink-equipped cooling apparatus of
the illustrated embodiment, as shown in FIG. 1, generally includes
a heat sink 1 and a cooling fan 3.
[0044] The heat sink 1 includes a base plate 5 having a front
surface 5a and a rear surface 5b with which a heat source is
contacted, as well as a radiation fin unit 7. The base plate 5 may
be made of a metal material such as, for example, aluminum alloy or
copper alloy or a plate-like structure exhibiting an internal heat
pipe function. Alternatively, it may be made of a non-metal
material such as a carbon sheet or the like. The base plate 5 is
formed at each of four corners thereof with a through-hole 8.
[0045] The radiation fin unit 7, as shown in FIG. 2, includes a
plurality of radiation fins 9 arranged in a manner to surround a
virtual central line CL defined so as to extend in a direction
perpendicular to the front surface 5a of the base plate 5 while
aligning the central line CL with a center of arrangement of the
radiation fins 9. In the illustrated embodiment, in order to
specify a configuration of the radiation fins 9 and a posture of
the radiation fins 9 with respect to the base plate 5, a plurality
of virtual vertical planes P are supposed which are defined so as
to extend in both a radial direction from the central line CL and a
vertical direction perpendicular to the front surface 5a of the
base plate 5 and be spaced from each other at equal intervals in a
circumferential direction of a virtual circle C defined about the
central line CL, as shown in FIG. 2. The plural radiation fins 9
are arranged so as to surround the central line CL while aligning
it with the center of arrangement of the radiation fins 9. The
plural radiation fins 9, as shown in FIG. 6, each include a lower
edge 9a positioned on a side of the base plate, an upper edge 9b
positioned opposite to the lower edge 9a, and a radiation surface
9c positioned between the lower edge 9a and the upper edge 9b. The
radiation fins 9 each are fixedly mounted on the front surface of
the base plate 5 so as to be positioned on an intersection line
between the virtual vertical plane P corresponding to each of the
lower edges 9a and each of the radiation fin mounting sections 11
contacted with the front surface 5a of the base plate 5. In the
illustrated embodiment, the radiation fins 9 each are formed by
bending of a metal plate as described below, resulting in being
made of two plates 10. The radiation fins 9 each are arranged
inclinedly or while being kept inclined so that an angle
(inclination angle) .theta. between the radiation surface 9c of the
radiation fin 9 and the virtual vertical plane P is less than 45
degrees. More specifically, the plural radiation fins 9 each are
inclined in the same direction with respect to the virtual vertical
plane P corresponding thereto or toward one side in the
circumferential direction of the virtual circle C. The inclination
angle .theta. is preferably set to be less than 45 degrees and more
than 15 degree. The angle set within such a range permits the
number of radiation fins 9 arranged to be increased to a degree
sufficient to permit the cooling apparatus of the illustrated
embodiment to exhibit satisfactory cooling performance.
Alternatively, inclination of the radiation fins 9 may be defined
by means of an angle .lambda. between each of the radiation fins 9
and each of the radiation fin mounting sections 11. The angle
.lambda. is preferably set to be more than 45 degrees and less than
85 degrees (45.degree.<.lambda.<85.degree.). Such an angular
range reduces a pressure loss of air flow, to thereby increase a
velocity of air flow occurring between the radiation fins 9 as
compared with the case of .lambda.=90.degree.. This permits the
amount of air discharged from the cooling apparatus to be
increased, so that it may be increased in cooling efficiency. An
optimum value of each of the angles .theta. and .lambda. may be
determined depending on a direction of rotation of an impeller of
the cooling fan 3 and a rotational speed thereof, an angle of
blades of the impeller, and an area of the radiation fins opposite
to the blades. Also, a direction in which the radiation fins 9 are
inclined may be opposite to that shown in FIG. 6, as shown in FIG.
7.
[0046] When a total radiation area of the radiation fins 9 is
indicated at F and an area of the front surface 5a of the base
plate 5 is indicated at S, the radiation fin unit 7 is preferably
constructed so that a ratio C=F/S is more than 10 and less than 40
(10<C<40). However, such conditions are not necessarily
required in the present invention.
[0047] Now, manufacturing of the radiation fin unit 7 constructed
as described above will be described. First, a thin metal plate 13
of an elongated shape which has a thickness of, for example, 1 mm
or less is prepared as shown in FIG. 2. Then, trough lines 14a and
15b and crest lines 15 are described on the plate 13. Thereafter,
as shown in FIG. 5, the plate 13 is subjected to repeated bending
along the trough lines 14a and 14b and crest lines 15 and then both
ends of the plate 13 are joined to each other, leading to
completion of the radiation fin unit 7 of an annular configuration
as shown in FIG. 2. The trough lines 14a and 14b in each pair shown
in FIG. 3 are arranged so as to directly intersect each other on
the plate 13. Alternatively, as shown in FIG. 4, the trough lines
14a and 14b may be arranged so as to intersect each other on
virtual extension lines thereof extending to an exterior of the
plate 15. In the radiation fin unit thus completed, the two trough
lines 14a and 14b positioned on each of both sides of each of the
crest lines 15 cooperate with each other to define each of the
lower edges of the radiation fin 9.
[0048] In each of FIGS. 3 and 4, the trough lines 14a and 14b are
arranged so as to define an angle .theta.' therebetween while being
kept from being parallel to each other. The above-described
inclination angle .theta. or .lambda. of each of the radiation fins
9 is determined depending on the angle .theta.'.
[0049] Joining between the base plate 5 and the radiation fin unit
7 is desirably carried out using a thermal conductive adhesion or
by soldering, brazing, welding, ultrasonic welding or the like,
because it is required to efficiently transmit heat from the base
plate 5 to the radiation fin unit 7.
[0050] Returning to FIG. 1, the cooling fan 3 includes the impeller
briefly described above which is designated at reference numeral
16. The impeller 16 includes the plural blades briefly described
above which are designated at reference numeral 17 and is rotated
by a motor 19. The motor 19 includes a housing supported on a
casing 21 through a plurality of webs (not shown). The casing 21
includes a lower surface, which is integrally provided on each of
four corners thereof with a pillar 23. The four pillars 23 each are
formed on a lower end thereof with a threaded hole, in which a
threaded portion of a screw inserted via a through-hole 8 formed
via each of four corners of the base plate 5 from the rear surface
5b of the base plate 5 to the front surface 5a thereof is
threadedly fitted. The cooling fan 3 is fixed on the base plate 5
by means of the screws (not shown) inserted via the through-holes 8
while keeping the pillars 23 abutted against the front surface 5a
of the base plate 5. This permits the radiation fin unit 7 and
cooling fan 3 to be arranged in positional relationship which
permits each of the blades 17 of the cooling fan 3 and the upper
edge 9a of each of the radiation fins 9 to be opposite to each
other. Each of the blades 17 and the upper edge 9a of each of the
radiation fins 9 are so positioned that a gap therebetween is set
to be within a range of, for example, between about 5 mm and about
10 mm. In the illustrated embodiment, the blades 17 of the cooling
fan 3 are arranged at an angle which permits air to be blown
against the radiation fins 9 of the radiation fin unit 7.
[0051] Then, air which has been thus blown against the radiation
fin unit 7 from the cooling fan 3 is permitted to enter a gap
between each adjacent two radiation fins 9 through an opening
defined between the upper edges 9a of each adjacent two radiation
fins 9 and then be radially outwardly discharged from the radiation
fin unit 7 through the gap.
[0052] When the impeller 16 of the cooling fan 3, as shown in FIG.
8, is rotated in a right-hand direction in FIG. 8, air sucked from
an upper portion of the blades 17 is permitted to have a component
in the direction of rotation of the impeller 16, to thereby be
discharged in directions of arrows indicated at reference numeral
25, resulting in pressure loss of the air being reduced. Such a
reduction in pressure loss permits the fins to be arranged at
significantly increased density, to thereby further enhance cooling
efficiency of the radiation fin unit 7.
[0053] A heat sink which has dimensions of 50 mm.times.50
mm.times.15 mm, an angle .lambda. of 55 degrees (angle .theta. of
45 degrees) and C of 17.4 was made of aluminum according to the
above-described construction of the illustrated embodiment. Then,
the heat sink thus manufactured was subjected to a test of cooling
performance under the conditions that the impeller of the axial fan
is set at a rotational speed of 4000 rpm and a heat source of 34 W
in power is kept contacted with the rear surface of the base plate
of the heat sink. As a result, it was confirmed that air is
discharged at a flow velocity of 2.8 m/s from an outer periphery of
the cooling fan unit of the heat sink and a temperature of the heat
source is raised to a level of 42.degree. C.
[0054] Also, a comparative test was carried out using a heat sink
wherein an inclination angle .theta. of each of radiation fins is
set to be 0 degree (.lambda.=90.degree.). As a result, the best
cooling performance was obtained at .lambda.=90.degree., C=8.2. At
this time, a flow velocity of air discharged was 2.1 m/s and a
temperature of a heat source was increased to a level of 48.degree.
C.
[0055] Referring now to FIGS. 9 to 16, a second embodiment of a
heat sink-equipped cooling apparatus according to the present
invention is illustrated. In connection with the illustrated second
embodiment, reference numerals correspond to those discussed in the
first embodiment described above, except with an additional prefix
of 100. The illustrated embodiment is essentially different in
structure and manufacturing of a heat sink from the first
embodiment described above. In the first embodiment, the radiation
fin unit for the heat sink 1 is formed of a single thin metal plate
by bending. On the contrary, in the illustrated embodiment, a
radiation fin unit 107 includes a plurality of radiation fins 109
each formed of a flat metal plate made by punching. Then, the
radiation fins 109 each are joined at a lower edge 109b thereof
(FIG. 14) to a fin mounting metal plate 108, resulting in the
radiation fin unit 107 being manufactured.
[0056] Now, manufacturing of the radiation fin unit 107 will be
described with reference to FIGS. 14 to 16. The radiation fins 109,
as shown in FIG. 14, each include in addition to the lower edge
109b, an upper edge 109a positioned opposite to the lower edge 109b
and a radiation surface 109c positioned between the lower edge 109b
and the upper edge 109a. The lower edge 109b of each of the
radiation fins 109 is integrally provided with a fit projection
109d. The fin mounting metal plate 108 is formed into a disc-like
shape and made so as to exhibit increased thermal conductivity. The
fin mounting metal plate 108, as shown in FIG. 15, is formed with a
plurality of slits S so as to radially extend from a central line
CL and be spaced from each other at predetermined intervals in a
circumferential direction of a virtual circle C. The slits S each
are included in each of a plurality of virtual vertical planes P
defined so as to extend in both a radial direction from the central
line CL and a direction perpendicular to a surface of the fin
mounting metal plate 108 and be spaced from each other at
predetermined intervals in the circumferential direction of the
virtual circle C. The slits S each are formed into a width larger
than a thickness of the radiation fin 109 and formed into
dimensions which permit each of the radiation fin 109 to be
inclined at a predetermined angle .theta. in a circumferential
direction of the virtual circle C while keeping each of the fit
projections 109d fitted in each of the slits S.
[0057] After the fit projection 109d of each of the radiation fins
109 is fitted in the slit S, the radiation fin 109 is inclined
toward one side in the circumferential direction of the virtual
circle C (or in a counterclockwise direction in FIG. 15), so that
the lower edge 109b may be joined to the fin mounting metal plate
108 in a manner to be heat-transferable or in a manner to permit
heat transfer to be carried out therebetween. Alternatively, the
joining may be carried out by means of an adhesive increased in
thermal conductivity or by soldering or the like. The radiation
fins 109 may be joined to the fin mounting metal plate 108 in
order. Alternatively, the joining may be executed by respectively
fitting the fit projections 109d of the radiation fins 109 in the
slits S and concurrently inclining the radiation fins 109 as
described above while previously applying a thermosetting adhesive
to a surface of the fan mounting metal plate 108, followed by
curing of the adhesive. This results in the radiation fin unit 107
being readily manufactured at a reduced cost. The slits S highly
facilitate positioning of the radiation fins 109 and joining of the
radiation fins 109 to the fin mounting metal plate 108.
[0058] The thus-manufactured radiation fin unit 107 is joined to a
front surface 105a of a base plate 105 using a joint means
increased in thermal conductivity. This results in providing a heat
sink structure which is constructed so that the radiation fins 109
each may be fixed indirectly on the front surface 105a of the base
plate 105 while being positioned along an intersection line between
the virtual vertical plane P corresponding to the lower edge 109b
of the radiation fin 109 and the front surface 105a of the base
plate 105, and the radiation fins 109 each may be inclined in an
identical direction with respect to the virtual vertical plane P
(or toward one side in the circumferential direction of the virtual
circle C) so as to form a predetermined inclination angle .theta.
between the radiation surface 109c of the radiation fin 109 and the
virtual vertical plane P. In the illustrated embodiment, the base
plate 105 and radiation fin unit 107 each may be formed of copper
alloy.
[0059] As will be noted from FIG. 12, the radiation fin unit 107
including the radiation fins 109 each having a main section formed
into a rectangular shape permits a space SP of a substantially
frust-conical shape to be formed in the radiation fin unit 107
while having a center positioned on or aligned with a central line
of the radiation fin unit and being gradually reduced in diameter
toward the base plate 105.
[0060] The cooling fan 103 shown in FIGS. 9 to 11 includes a casing
121 integrally formed of a synthetic resin material. The casing 121
includes a casing body 121b provided with an air duct 121a in a
manner to surround at least a part of a periphery of an impeller
116, three webs 122 for supporting a housing of a motor 119 on the
casing body 121b, and four pillars 123 each mounted at one end
thereof on the casing body 121b and held at the other end thereof
on the base plate 105. The casing body 121b is provided with a
plurality of contact sections 124 which are contacted with an outer
surface of the radiation fin unit 107 to prevent lateral movement
of the casing 121. The pillars 123 each are provided at the other
end thereof with a hook acting as a held portion. Correspondingly,
the base plate 105 is formed at each of four corners with a
through-hole 108 acting as a holding portion in which the hook of
each of the pillars 123 is held.
[0061] The illustrated embodiment is different in relationship
between blades of the impeller and the radiation fins from the
first embodiment described above. More specifically, in the
illustrated embodiment, a plurality of blades 117 of the impeller
116 are arranged in the same direction as the radiation fins 109.
Also, the cooling fan 103 is operated to rotate the impeller 107 in
a direction in which the radiation fins 109 are inclined. Such
configuration permits the cooling apparatus of the illustrated
embodiment to be increased in cooling performance as compared with
the contrary case.
[0062] In the illustrated embodiment as well, the inclination angle
.theta. of the radiation fins 109 and the like may be set as in the
first embodiment described above.
[0063] In the illustrated embodiment, the radiation fins 109 are
fixed on the fin mounting metal plate 108. Alternatively, as shown
in FIG. 17, a base plate 205 may be formed with a plurality of
slits S. The slits S thus formed each have the fit projection 109d
of each of the radiation fins 109 to be fitted therein, to thereby
construct the heat sink.
[0064] Also, the radiation fin unit may be configured as shown in
FIG. 18. In FIG. 18, radiation fins 209 each are provided at a
lower edge 209b thereof with a flange 209e for fixing. In this
instance, a radiation surface 209c and the flange 209e may be so
arranged that an angle therebetween is set to be
90.degree.+.theta.. Such arrangement ensures that the inclination
angle .theta. of the radiation fins 209 may be positively provided.
The radiation fins 209 may be mounted on the fin mounting metal
plate free from any slit. In addition, as shown in each of FIGS. 19
and 20, the flange 209e may be fixed directly on the front surface
105a of the base plate 105.
[0065] Further, a radiation fit unit may be constructed in such a
manner as shown in FIGS. 21 and 22. More specifically, radiation
fins 309 constructed in a simplified manner each are joined
directly to the main plate 105.
[0066] As can be seen from the foregoing, the cooling apparatus of
the present invention exhibits cooling performance at substantially
the same level as an expensive cooling apparatus conventionally
used without being increased in dimensions in a radial direction
thereof and ensuring satisfactory durability of the motor.
[0067] While preferred embodiments of the invention have been
described with a certain degree of particularity with reference to
the drawings, obvious modifications and variations are possible in
light of the above teachings. It is therefore to be understood that
within the scope of the appended claims, the invention may be
practiced otherwise than as specifically described.
* * * * *