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.

Description

BACKGROUND

1. Technical Field

The disclosure generally relates to heat dissipation devices; and more particularly to a heat dissipation device incorporating an airflow generator.

2. Description of Related Art

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.

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.

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.

What is needed, therefore, is a heat dissipation device to overcome the above-described limitations.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

FIG. 1 is an isometric, assembled view of a heat dissipation device in accordance with an exemplary embodiment of the present disclosure.

FIG. 2 is an exploded view of the heat dissipation device of FIG. 1.

FIG. 3 is similar to FIG. 2, but viewed from a different aspect.

FIG. 4 is a cross-sectional view of the heat dissipation device of FIG. 1, taken along a line IV-IV thereof.

FIG. 5 is a view schematically showing a first stage of an operation process of the heat dissipation device of FIG. 1.

FIG. 6 is similar to FIG. 5, showing a second stage of the operation process of the heat dissipation device of FIG. 1.

FIG. 7 is similar to FIG. 5, showing a third stage of the operation process of the heat dissipation device of FIG. 1.

FIG. 8 is an isometric, assembled view of a heat dissipation device in accordance with a second embodiment of the present disclosure.

DETAILED DESCRIPTION

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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; anda 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; andan 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; anda 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.