U.S. patent application number 12/818113 was filed with the patent office on 2011-11-17 for airflow generator and heat dissipation device incorporating the same.
This patent application is currently assigned to FOXCONN TECHNOLOGY CO., LTD.. Invention is credited to CHIEN-YU CHAO, YEN-CHIH CHEN.
Application Number | 20110277968 12/818113 |
Document ID | / |
Family ID | 44910715 |
Filed Date | 2011-11-17 |
United States Patent
Application |
20110277968 |
Kind Code |
A1 |
CHAO; CHIEN-YU ; et
al. |
November 17, 2011 |
AIRFLOW GENERATOR AND HEAT DISSIPATION DEVICE INCORPORATING THE
SAME
Abstract
An airflow generator includes stacked airflow-generating units.
Each airflow-generating unit includes a casing, first and second
vibrating diaphragms received in the casing and spaced from each
other, first and second driving members for driving the first and
second vibrating diaphragms, and a nozzle connected to the casing.
An inner space of the casing is divided into a first chamber formed
between the first and second vibrating diaphragms, and a second
chamber and a third chamber located at two opposite sides of the
first chamber. The first driving member includes a first movable
magnet attached to the first vibrating diaphragm, and a first
stationary magnet received in the second chamber and attached to
the casing. The second driving member includes a second movable
magnet attached to the second vibrating diaphragm, and a second
stationary magnet received in the third chamber and attached to the
casing.
Inventors: |
CHAO; CHIEN-YU; (Tu-Cheng,
TW) ; CHEN; YEN-CHIH; (Tu-Cheng, TW) |
Assignee: |
FOXCONN TECHNOLOGY CO.,
LTD.
Tu-Cheng
TW
|
Family ID: |
44910715 |
Appl. No.: |
12/818113 |
Filed: |
June 17, 2010 |
Current U.S.
Class: |
165/120 ;
417/410.1 |
Current CPC
Class: |
H01L 2924/0002 20130101;
H01L 23/467 20130101; F04B 43/043 20130101; F28F 13/06 20130101;
F04B 45/04 20130101; F04B 45/043 20130101; F28F 2250/08 20130101;
H05K 7/20172 20130101; F04B 53/1077 20130101; F28F 2265/28
20130101; H01L 2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
165/120 ;
417/410.1 |
International
Class: |
F28F 13/00 20060101
F28F013/00; F04B 17/00 20060101 F04B017/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 14, 2010 |
TW |
99115391 |
Claims
1. An airflow generator, comprising: at least one
airflow-generating unit, comprising: a casing; a first and a second
vibrating diaphragms received in the casing and spaced from each
other, an inner space of the casing being divided into a first
chamber formed between the first and second vibrating diaphragms,
and a second chamber and a third chamber located at two opposite
sides of the first chamber, the second chamber and the third
chamber being isolated from the first chamber by the first and
second vibrating diaphragms, respectively; a nozzle connected to a
sidewall of the casing and located at a position corresponding to
the first chamber, an air channel being defined in the nozzle and
communicating the first chamber with an outer environment; a first
driving member adapted for driving the first vibrating diaphragm,
the first driving member comprising a first movable magnet attached
to the first vibrating diaphragm, and a first stationary magnet
received in the second chamber and attached to the casing at a
position corresponding to the first movable magnet; and a second
driving member adapted for driving the second vibrating diaphragm,
the second driving member comprising a second movable magnet
attached to the second vibrating diaphragm, and a second stationary
magnet received in the third chamber and attached to the casing at
a position corresponding to the second movable magnet; wherein when
the first and second driving members drive the first and second
vibrating diaphragms to move towards each other, the first and
second vibrating diaphragms compress the air inside the first
chamber of the casing to move towards the air channel of the
nozzle, thereby generating an airflow jetting to the outer
environment through the nozzle.
2. The airflow generator of claim 1, wherein one of the first
movable magnet and the first stationary magnet of the first driving
member is a permanent magnet, the other one of the first movable
magnet and the first stationary magnet of the first driving member
is an electromagnet, one of the second movable magnet and the
second stationary magnet of the second driving member is a
permanent magnet, the other one of the second movable magnet and
the second stationary magnet of the second driving member is an
electromagnet.
3. The airflow generator of claim 2, wherein the first and second
movable magnets are electromagnets, and the first and second
stationary magnets are permanent magnets.
4. The airflow generator of claim 3, wherein the first movable
magnet comprises a movable iron core and a wire coil disposed
around the iron core.
5. The airflow generator of claim 3, wherein the second movable
magnet comprises a movable iron core and a wire coil disposed
around the iron core.
6. The airflow generator of claim 1, wherein the first and second
vibrating diaphragms are parallel to each other, the first
vibrating diaphragm and the second vibrating diaphragm being spaced
apart by a first distance, the first movable magnet and the first
stationary magnet being spaced apart by a second distance, the
second movable magnet and the second stationary magnet being spaced
apart by a third distance, and both the second distance and the
third distance being shorter than the first distance,
respectively.
7. The airflow generator of claim 1, wherein a first
electromagnetic interference shielding layer and a second
electromagnetic interference shielding layer are formed on the
casing, and on the first and second vibrating diaphragms, the first
electromagnetic interference shielding layer encircles the second
chamber, and the second electromagnetic interference shielding
layer encircles the third chamber.
8. The airflow generator of claim 1, wherein the first and second
movable magnets are attached to the middle portions of the first
and second vibrating diaphragms, respectively.
9. The airflow generator of claim 1, further comprising a shell,
wherein the at least one airflow-generating unit is mounted in the
shell.
10. A heat dissipation device, comprising: a heat sink defining a
plurality of air passages therein; and an airflow generator
disposed at a side of the heat sink, the airflow generator
comprising: a plurality of airflow-generating units stacked
together, each of the airflow-generating units comprising: a
casing; a first and a second vibrating diaphragms received in the
casing and spaced from each other, an inner space of the casing
being divided into a first chamber formed between the first and
second vibrating diaphragms, and a second chamber and a third
chamber located at two opposite sides of the first chamber, the
second chamber and the third chamber being isolated from the first
chamber by the first and second vibrating diaphragms, respectively;
a nozzle connected to a sidewall of the casing and located at a
position corresponding to the first chamber, an air channel being
defined in the nozzle and communicating the first chamber with an
outer environment; a first driving member adapted for driving the
first vibrating diaphragm, the first driving member comprising a
first movable magnet attached to the first vibrating diaphragm, and
a first stationary magnet received in the second chamber and
attached to the casing at a position corresponding to the first
movable magnet; and a second driving member adapted for driving the
second vibrating diaphragm, the second driving member comprising a
second movable magnet attached to the second vibrating diaphragm,
and a second stationary magnet received in the third chamber and
attached to the casing at a position corresponding to the second
movable magnet; wherein when the first and second driving member
drive the first and second vibrating diaphragms to move towards
each other, the first and second vibrating diaphragms compress the
air inside the first chamber of the casing to move towards the air
channel of the nozzle, thereby generating an airflow jetting
towards the air passages of the heat sink through the nozzle.
11. The heat dissipation device of claim 10, wherein one of the
first movable magnet and the first stationary magnet of the first
driving member is a permanent magnet, the other one of the first
movable magnet and the first stationary magnet of the first driving
member is an electromagnet, one of the second movable magnet and
the second stationary magnet of the second driving member is a
permanent magnet, the other one of the second movable magnet and
the second stationary magnet of the second driving member is an
electromagnet.
12. The heat dissipation device of claim 11, wherein the first and
second movable magnets are electromagnets, and the first and second
stationary magnets are permanent magnets.
13. The heat dissipation device of claim 12, wherein the first
movable magnet comprises a movable iron core and a wire coil
disposed around the iron core.
14. The heat dissipation device of claim 12, wherein the second
movable magnet comprises a movable iron core and a wire coil
disposed around the iron core.
15. The heat dissipation device of claim 10, wherein the first and
second vibrating diaphragms are parallel to each other, the first
vibrating diaphragm and the second vibrating diaphragm being spaced
apart by a first distance, the first movable magnet and the first
stationary magnet being spaced apart by a second distance, the
second movable magnet and the second stationary magnet being spaced
apart by a third distance, and both the second distance and the
third distance being shorter than the first distance,
respectively.
16. The heat dissipation device of claim 10, wherein a first
electromagnetic interference shielding layer and a second
electromagnetic interference shielding layer are formed on the
casing, and on the first and second vibrating diaphragms, the first
electromagnetic interference shielding layer encircles the second
chamber, and the second electromagnetic interference shielding
layer encircles the third chamber.
17. The heat dissipation device of claim 10, wherein the first and
second movable magnets are attached to the middle portions of the
first and second vibrating diaphragms, respectively.
18. The heat dissipation device of claim 10, wherein the airflow
generator further comprises a shell, and the airflow-generating
units being mounted in the shell.
19. The heat dissipation device of claim 10, further comprising an
additional airflow generator, wherein the additional airflow having
a conformation the same as the airflow generator, the additional
airflow generator being arranged at a side of the airflow generator
opposite to the heat sink, with the nozzle of each
airflow-generating unit thereof pointing in a direction opposite to
the nozzle of each airflow-generating unit of the airflow
generator.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The disclosure generally relates to heat dissipation
devices; and more particularly to a heat dissipation device
incorporating an airflow generator.
[0003] 2. Description of Related Art
[0004] With accelerated developments in the electronic information
industries, electronic components such as central processing units
(CPUs) of computers are now capable of operating at much higher
frequencies and speeds. As a result, the heat generated by these
CPUs during normal operation is commensurately increased. If not
quickly removed from the CPUs, this generated heat may cause them
to become overheated and finally affecting their workability and
stability.
[0005] In order to remove the heat of the CPUs and hence enable the
CPUs to continue normal operations, heat dissipation devices are
provided to dissipate heat of the CPUs. A conventional heat
dissipation device includes a fan, and a heat sink arranged at an
outlet of the fan. The heat sink is attached on a CPU or thermally
connected to the CPU via a heat pipe. Heat generated by the CPU is
transferred to a plurality of fins of the heat sink. Airflow
produced by the fan flows towards the fins of the heat sink to
dissipate heat of the CPU to the outside environment, and thus
maintains the stability and normal operations of the CPU.
[0006] However, when the fan runs at a higher speed, the fan
exhibits a noticeable noise. Furthermore, an impeller of the fan
usually occupies a larger volume, which increases the size of the
heat dissipation device. Therefore, this goes against the need for
requiring more compact size in electronic products.
[0007] What is needed, therefore, is a heat dissipation device to
overcome the above-described limitations.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Many aspects of the present embodiments can be better
understood with reference to the following drawings. The components
in the drawings are not necessarily drawn to scale, the emphasis
instead being placed upon clearly illustrating the principles of
the present embodiments. Moreover, in the drawings, like reference
numerals designate corresponding parts throughout the several
views.
[0009] FIG. 1 is an isometric, assembled view of a heat dissipation
device in accordance with an exemplary embodiment of the present
disclosure.
[0010] FIG. 2 is an exploded view of the heat dissipation device of
FIG. 1.
[0011] FIG. 3 is similar to FIG. 2, but viewed from a different
aspect.
[0012] FIG. 4 is a cross-sectional view of the heat dissipation
device of FIG. 1, taken along a line IV-IV thereof.
[0013] FIG. 5 is a view schematically showing a first stage of an
operation process of the heat dissipation device of FIG. 1.
[0014] FIG. 6 is similar to FIG. 5, showing a second stage of the
operation process of the heat dissipation device of FIG. 1.
[0015] FIG. 7 is similar to FIG. 5, showing a third stage of the
operation process of the heat dissipation device of FIG. 1.
[0016] FIG. 8 is an isometric, assembled view of a heat dissipation
device in accordance with a second embodiment of the present
disclosure.
DETAILED DESCRIPTION
[0017] Referring to FIGS. 1-3, a heat dissipation device 100
according to an exemplary embodiment of the present disclosure is
shown. The heat dissipation device 100 includes an airflow
generator 10 and a heat sink 20.
[0018] Referring also to FIG. 4, the airflow generator 10 includes
a shell 11 and a plurality of airflow-generating units 12. The
airflow-generating units 12 are arranged in the shell 11, and are
stacked together along a horizontal direction. Each
airflow-generating unit 12 includes a casing 120, a first vibrating
diaphragm 121, a second vibrating diaphragm 122, a first driving
member 13, a second driving member 14, and a nozzle 123.
[0019] The casing 120 has a cuboid shape. The first and second
vibrating diaphragms 121, 122 are horizontally mounted in the
casing 120 at different levels. The first and second vibrating
diaphragms 121, 122 are spaced from and parallel to each other. An
inner space of the casing 120 is divided into three chambers by
using the first and second vibrating diaphragms 121, 122; i.e., a
first chamber 124 is formed between the first and second vibrating
diaphragms 121, 122, a second chamber 125 located above the first
chamber 124 and isolated from the first chamber 124 is formed by
the first vibrating diaphragm 121, and a third chamber 126 located
below the first chamber 124 and isolated from the first chamber 124
is formed by the second vibrating diaphragm 122. The first
vibrating diaphragm 121 and the second vibrating diaphragm 122 are
spaced apart by a first distance H1. Each of the first and second
vibrating diaphragms 121, 122 is made of elastic material, such as
rubber, flexible resin or a thin metal sheet.
[0020] The first driving member 13 is received in the second
chamber 125 of the casing 120, and includes a first movable magnet
131 and a first stationary magnet 132. The first movable magnet 131
is attached to a middle of a top surface of the first vibrating
diaphragm 121. The first stationary magnet 132 is attached to an
inner surface of a top wall of the casing 120. The first movable
magnet 131 and the first stationary magnet 132 face each other, and
are spaced apart by a second distance H2. The second distance H2 is
shorter than the first distance H1 between the first and second
vibrating diaphragms 121, 122.
[0021] The second driving member 14 is received in the third
chamber 126 of the casing 120, and includes a second movable magnet
141 and a second stationary magnet 142. The second movable magnet
141 is attached to a middle of a bottom surface of the second
vibrating diaphragm 122. The second stationary magnet 142 is
attached to an inner surface of a bottom wall of the casing 120.
The second movable magnet 141 and the second stationary magnet 142
face each other, and are spaced apart by a third distance H3. The
third distance H3 is substantially equal to the second distance H2
between the first movable magnet 131 and the first stationary
magnet 132, and is shorter than the first distance H1 between the
first and second vibrating diaphragms 121, 122.
[0022] In this embodiment, both the first movable magnet 131 of the
first driving member 13 and the second movable magnet 141 of the
second driving member 14 are electromagnets, and both the first
stationary magnet 132 of the first driving member 13 and the second
stationary magnet 142 of the second driving member 14 are permanent
magnets. The first movable magnet 131 includes a movable iron core
1311 (comprising a shape of a thin piece) and a wire coil 1312
disposed around the movable iron core 1311. The movable iron core
1311 is made of a material which can be easily magnetized and
demagnetized, such as soft iron or silicon steel. The wire coil
1312 is attached on the first vibrating diaphragm 121 and surrounds
the iron core 1311. Alternatively, the wire coil 1312 can be
directly wound on and around the iron core 1311. The second movable
magnet 141 includes a movable iron core 1411 and a wire coil 1412
disposed around the iron core 1411. The iron core 1411 is made of a
material which can be easily magnetized and demagnetized, such as
soft iron or silicon steel. The wire coil 1412 is attached on the
second vibrating diaphragm 122 and surrounds the iron core 1411.
Alternatively, the wire coil 1412 can be directly wound on and
around the iron core 1411. A plurality of through holes (not
labeled) are defined in a sidewall of the casing 120 of each
airflow-generating unit 12 for facilitating the extension of an
electric wire 127 therethrough to connect the wire coils 1312 of
the first movable magnets 131 of adjacent airflow-generating units
12 and for facilitating the extension of an electric wire 128
therethrough to connect the wire coils 1412 of the second movable
magnets 141 of adjacent airflow-generating units 12. When the
airflow-generating units 12 are assembled together, the wire coils
1312 of the first movable magnets 131 of the airflow-generating
units 12 are connected to each other in series via the electric
wires 127, and the wire coils 1412 of the second movable magnets
141 of the airflow-generating units 12 are connected to each other
in series via the electric wires 128. Both the wire coils 1312 of
the first movable magnets 131 and the wire coils 1412 of the second
movable magnets 141 of the airflow-generating units 12 are
connected to an external power supply (not shown).
[0023] The nozzle 123 is disposed at a lateral side of the casing
120 facing the heat sink 20. The nozzle 123 is connected to a
middle portion of the sidewall of the casing 120 corresponding to
the first chamber 124. The nozzle 123 defines a tapered air channel
1231 therein. A larger end of the air channel 1231 communicates
with the first chamber 124, and a smaller end of the air channel
1231 faces the heat sink 20.
[0024] The shell 11 defines a receiving room (not labeled) therein
with an opening 111 thereof facing the heat sink 20. The stacked
airflow-generating units 12 are arranged into the shell 11 via the
opening 111. The shell 11 is used for fixing the stacked
airflow-generating units 12 together. In another embodiment, the
stacked airflow-generating units 12 can be fixed together by
adhesive or glue.
[0025] The heat sink 20 includes a plurality of spaced fins 21. A
plurality of air passages 22 are formed between adjacent fins 21.
The airflow generator 10 is arranged at a lateral side of the heat
sink 20, with the nozzles 123 of the airflow-generating units 12
facing the air passages 22 of the heat sink 20. The smaller end of
the nozzle 123 of each airflow-generating unit 12 is spaced from an
entrance of a corresponding air passage 22 of the heat sink 20 by a
predetermined distance.
[0026] In operation of each airflow-generating unit 12, the
external power supply provides an alternating current to the wire
coil 1312 of the first movable magnet 131 of the first driving
member 13 and the wire coil 1412 of the second movable magnet 141
of the second driving member 14 of the airflow-generating unit 12
via the wires 127, 128. When a current is passed through the wire
coil 1312 of the first movable magnet 131 of the first driving
member 13, the iron core 1311 of the first movable magnet 131 is
magnetized to create a large magnetic field that extends into the
space around the iron core 1311. Similarly, when a current is
passed through the wire coil 1412 of the second movable magnet 141
of the second driving member 14, the iron core 1411 of the second
movable magnet 141 is magnetized to create a large magnetic field
that extends into the space around the iron core 1411. The
polarities of the magnetized first and second movable magnets 131,
141 are determined by the direction of the current flowing through
the wire coils 1312, 1412. The magnetized first movable magnet 131
and the first stationary magnet 132 of the first driving member 13
mutually attract or repel each other alternately, and the
magnetized second movable magnet 141 and the second stationary
magnet 142 of the second driving member 14 also mutually attract or
repel each other alternately, thereby causing the first and second
vibrating diaphragms 121, 122 to move towards each other or away
from each other simultaneously with the first and second movable
magnets 131, 141. When the first and second driving members 13, 14
drive the first and second vibrating diaphragms 121, 122 to move
towards each other simultaneously, the first and second vibrating
diaphragms 121, 122 compress the air inside the first chamber 124
to move towards the air channel 1231 of the nozzle 123, thereby
generating an airflow jetting towards the air passages 22 of the
heat sink 20 from the smaller end of the nozzle 123. The airflow
then flows along the air passages 22 of the heat sink 20 to take
away the heat transferred to the fins 21.
[0027] Referring to FIGS. 5-7, an airflow-generating process of
each airflow-generating unit 12 in one generating period is
described in detail as follows.
[0028] The airflow-generating process is divided into three stages.
During the first stage of the airflow-generating process, the
external power supply provides a negative/positive current to the
wire coil 1312 of the first movable magnet 131 to magnetize the
iron core 1311 of the first movable magnet 131. The iron core 1311
then becomes magnetized. An end of the magnetized iron core 1311
adjacent to the first stationary magnet 132 has a magnetic polarity
the same as that of an end of the first stationary magnet 132
adjacent to the magnetized iron core 1311. The magnetized iron core
1311 of the first movable magnet 131 is thereby repelled by the
first stationary magnet 132, thus driving the first vibrating
diaphragm 121 to move towards the second vibrating diaphragm 122
with the magnetized iron core 1311. At the same time, the external
power supply provides a negative/positive current to the wire coil
1412 of the second movable magnet 141 to magnetize the iron core
1411 of the second movable magnet 141. The iron core 1411 then
becomes magnetized. An end of the magnetized iron core 1411
adjacent to the second stationary magnet 142 has a magnetic
polarity the same as that of an end of the second stationary magnet
142 adjacent to the magnetized iron core 1411. The magnetized iron
core 1411 of the second movable magnet 141 is repelled by the
second stationary magnet 142, thus driving the second vibrating
diaphragm 122 to move towards the first vibrating diaphragm 121
with the magnetized iron core 1311. In other words, the first and
second driving members 13, 14 drive both the first and second
vibrating diaphragms 121, 122 to move towards each other during the
first stage of the airflow-generating process. Thus, the air in the
first chamber 124 is compressed by the first and second vibrating
diaphragms 121, 122 to move towards the air channel 1231 of the
nozzle 123.
[0029] Referring to FIG. 5, when the first and second vibrating
diaphragms 121, 122 move from their originally horizontal positions
to a plurality of curved positions or contours as indicated by a
plurality of broken lines 121a, 122a, a first airflow 31 is
generated and jets towards the air passages 22 of the heat sink 20
from the outer end of the nozzle 123 having a high flow speed. The
first airflow 31 flows forward along the air passages 22 of the
heat sink 20 and exchanges heat with the fins 21 to take away the
heat transferred to the fins 21.
[0030] Then the negative/positive current supplied to the wire coil
1312 of the first movable magnet 131 reverses current direction to
change to a positive/negative current, thereby entering the second
stage of the airflow-generating process. When the iron core 1311 is
magnetized by the reversed positive/negative current, the end of
the magnetized iron core 1311 adjacent to the first stationary
magnet 132 has a magnetic polarity opposite to that of the end of
the first stationary magnet 132 adjacent to the magnetized iron
core 1311. The magnetized iron core 1311 of the first movable
magnet 131 is attracted by the first stationary magnet 132, thereby
driving the first vibrating diaphragm 121 to move away from the
second vibrating diaphragm 122 together with the magnetized iron
core 1311. At the same time, the negative/positive current supplied
to the wire coil 1412 of the second movable magnet 141 also
reverses direction to change to the positive/negative current. When
the iron core 1411 is magnetized by the reversed positive/negative
current, the end of the magnetized iron core 1411 adjacent to the
second stationary magnet 142 has a magnetic polarity opposite to
that of an end of the second stationary magnet 142 adjacent to the
magnetized iron core 1411. The magnetized iron core 1411 of the
second movable magnet 141 is then repelled by the second stationary
magnet 142, thereby driving the second vibrating diaphragm 122 to
move away from the first vibrating diaphragm 121 together with the
magnetized iron core 1411. In other words, the first and second
driving members 13, 14 drive the first and second vibrating
diaphragms 121, 122 to move away from each other during the second
stage of the airflow-generating process.
[0031] Referring to FIG. 6, when the first and second vibrating
diaphragms 121, 122 move from their curved positions as indicated
by the broken lines 121a, 122a (see in FIG. 5) back to their
original horizontal positions, the air outside and around the
nozzle 123 is sucked into the air passages 22 of the heat sink 20,
thereby forming a second airflow 32 flowing forward along the air
passages 22 of the heat sink 20. Particularly, the second airflow
32 has a flow rate ten times as large as the first airflow 31.
[0032] After the first and second vibrating diaphragms 121, 122
have moved back to their horizontal positions, the third stage of
the airflow-generating process then begins as follow. Referring to
FIG. 7, the first and second vibrating diaphragms 121, 122 continue
to move away from each other until the first and second vibrating
diaphragms 121, 122 reach their curved positions as indicated by
the broken lines 121b, 122b. During the third stage of the
airflow-generating process, a volume of the first chamber 124 is
expanded, thereby allowing the cool air (indicated by a plurality
of arrows 33) outside and around the nozzle 123 to be sucked into
the first chamber 124 of the casing 120 for a subsequent
airflow-generating process. Then the positive/negative current
supplied to the wire coils 1312, 1412 of the first and second
movable magnets 131, 141 reverse current direction to change to a
negative/positive current, thereby entering the first stage of the
subsequent airflow-generating process.
[0033] In each airflow-generating unit 12, the first distance H1
between the first and second vibrating diaphragms 121, 122 is
properly over two times longer than the second distance H2 between
the first movable magnet 131 and the first stationary magnet 132,
thereby reducing the interaction between the first movable magnet
131 of the first driving member 13 and the second driving member
14. Similarly, the first distance H1 between the first and second
vibrating diaphragms 121, 122 is properly over two times longer
than the third distance H3 between the second movable magnet 141
and the second stationary magnet 142, thereby reducing the
interaction between the second movable magnet 141 of the second
driving member 14 and the first driving member 13.
[0034] In the airflow-generating process of each airflow-generating
unit 12, the external power supply can provide a pulse current to
the wire coils 1312, 1412 of the first and second movable magnets
131, 141. In such circumstances, the current supplied to the wire
coils 1312, 1412 of the first and second movable magnets 131, 141
is zero during the second and third stages of the
airflow-generating process.
[0035] In each airflow-generating unit 12, by exchanging the
positions of the first movable magnet 131 and the first stationary
magnet 132 of the first driving member 13, and maintaining the
positions of the second movable magnet 141 and the second
stationary magnet 142 of the second driving member 14 unchanged,
the airflow-generating unit 12 can also achieve the above
airflow-generating process. By exchanging the positions of the
second movable magnet 141 and the second stationary magnet 142 of
the second driving member 14, and maintaining the positions of the
first movable magnet 131 and the first stationary magnet 132 of the
first driving member 13 unchanged, the airflow-generating unit 12
can also achieve the above airflow-generating process. By
exchanging or switching the positions of the first movable magnet
131 and the first stationary magnet 132 of the first driving member
13, and exchanging or switching the positions of the second movable
magnet 141 and the second stationary magnet 142 of the second
driving member 14, the airflow-generating unit 12 can also achieve
the above airflow-generating process.
[0036] In each airflow-generating unit 12, under the alternating
current, the first and second driving member 13, 14 drive the first
and second vibrating diaphragms 121, 122 to periodically compress
the air inside the first chamber 124 of the casing 120, thereby
periodically generating an airflow jetting towards the air passages
22 of the heat sink 20 from the outer end of the nozzle 123. By
supplying alternating currents of different frequencies, the flow
rate of the airflow generated by the airflow-generating unit 12 can
be adjusted to meet different cooling requirements.
[0037] Further, a first electromagnetic interference (EMI)
shielding layer 1251 is formed on an inner surface of the casing
120 and the bottom surface of the first vibrating diaphragm 121,
and encircles the second chamber 125. The first EMI shielding layer
1251 encloses the first driving member 13 therein, thereby
preventing EMI radiation from the first movable magnet 131 of the
first driving member 13 to interact with the electronic components
outside the shell 11 of the air airflow generator 10. A second
electromagnetic interference (EMI) shielding layer 1261 is formed
on the inner surface of the casing 120 and the bottom surface of
the second vibrating diaphragm 122, and encircles the third chamber
126. The second EMI shielding layer 1261 encloses the second
driving member 14 therein, thereby preventing EMI radiation from
the second movable magnet 141 of the second driving member 14 to
interact with the electronic components outside the shell 11 of the
air airflow generator 10.
[0038] In the heat dissipation device 100, the heat transferred to
the fins 21 of the heat sink 20 is dissipated by the airflow
generator 10. The number of airflow-generating units 12 of the
airflow generator 10 for actual implementation can be chosen so as
to meet the specific cooling requirements. Further, no motor and
impeller are used in the heat dissipation device 100, thus the heat
dissipation device 100 can have a smaller size, and a quieter
working environment is obtained.
[0039] Referring to FIG. 8, a heat dissipation device 100a
according to a second embodiment is illustrated. Comparing with the
heat dissipation device 100 illustrated in FIGS. 1-4, this heat
dissipation device 100 has an additional airflow generator 10a. In
other words, the heat dissipation device 100 of the second
embodiment includes the heat sink 20, the airflow generator 10 and
the airflow generator 10a. The airflow generator 10a has a
conformation or structure the same as the airflow generator 10, and
includes a plurality of stacked airflow-generating units 12. The
airflow generator 10a is arranged at a side of the airflow
generator 10 which sits opposite to the heat sink 20, with the
nozzle 123 of each airflow-generating unit 12 thereof pointing in a
direction opposite to the nozzle 123 of each airflow-generating
unit 12 of the airflow generator 10.
[0040] It is to be understood, however, that even though numerous
characteristics and advantages of the present embodiments have been
set forth in the foregoing description, together with details of
the structures and functions of the embodiments, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size, and arrangement of parts within the
principles of the disclosure to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
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