HEAT DISSIPATION APPARATUS INCORPORATING AIRFLOW GENERATOR

Abstract

A heat dissipation apparatus includes a heat sink defining a plurality of air passages therein, and an airflow generator arranged on the heat sink and including a plurality of airflow-generating units. Each airflow-generating unit includes a casing, and a vibration diaphragm and a driving member arranged in the casing. The vibration diaphragm divides an inner space of the casing into first and second chamber isolated from each other. The second chamber communicates with the exterior via an orifice defined in a bottom wall of the casing. The driving member is capable of vibrating the vibration diaphragm when alternating voltage is applied thereto. When the driving member vibrates the vibration diaphragm towards the bottom wall of the casing, the vibration diaphragm compresses the air inside the second chamber of the casing towards the orifice, generating airflow from the orifice to the air passages of the heat sink.

Description

BACKGROUND

1. Technical Field

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

2. Description of Related Art

With developments in electronic components such as central processing units (CPUs), such components are nowadays capable of operating at very high speeds. The amount of heat generated by such components during normal operation is commensurately large. If not quickly removed from a CPU, this generated heat may cause the CPU to become overheated and finally affect its workability and stability.

In order to remove the heat from a CPU and hence ensure normal operation, a heat dissipation device is usually provided. A frequently used heat dissipation device includes a fan, a heat sink arranged at an outlet of the fan, and a heat pipe thermally connecting the heat sink with the CPU. Heat generated by the CPU is transferred to fins on the heat sink via the heat pipe. Airflow from the fan crosses the fins of the heat sink and removes the heat from the fins to the exterior of the system.

However, the fan includes an impeller that is driven by an electric motor. When the fan runs at high speed, it generates noise. In addition, the impeller of the fan usually increases the size of the heat dissipation device, compromising efforts to limit the size of the corresponding electronic product.

What is needed, therefore, is a means to overcome the 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 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 apparatus in accordance with a first exemplary embodiment of the present disclosure.

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

FIG. 3 is an exploded view of an airflow generator of the heat dissipation apparatus of FIG. 2.

FIG. 4 is an inverted view of FIG. 3.

FIG. 5 is a cross-section of the heat dissipation apparatus of FIG. 1, taken along a line V-V thereof.

FIG. 6 is a schematic view corresponding to FIG. 5, showing a first stage of operation of one airflow-generating unit of the heat dissipation apparatus of FIG. 1.

FIG. 7 is similar to FIG. 6, but showing a second stage of operation of the airflow-generating unit.

FIG. 8 is similar to FIG. 7, but showing a third stage of operation of the airflow-generating unit.

FIG. 9 is a cross-section of a heat dissipation apparatus in accordance with a second exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

Referring to FIGS. 1-2, a heat dissipation apparatus 100 according to a first exemplary embodiment of the present disclosure is shown. The heat dissipation apparatus 100 includes a heat sink 10, and an airflow generator 20 mounted on the heat sink 10. In a typical application, a heat source (not shown), such as an electronic component, generates heat, and such heat is transferred from the heat source to the heat sink 10.

The heat sink 10 includes a rectangular base 11 for contacting the heat source to absorb heat therefrom, and a plurality of spaced fins 12 formed on the base 11. A plurality of air passages 13 is defined between adjacent fins 12. The heat sink 10 forms four mounting portions 14 at four corners thereof. Each mounting portion 14 defines a mounting hole 15 therein.

Referring also to FIGS. 3-4, the airflow generator 20 includes a shell 30 and a plurality of airflow-generating units 40 arranged in the shell 30. The shell 30 includes a base plate 31 and a cover 32 connected to the base plate 31. The cover 32 includes a generally rectangular top plate 321 having four cutouts 3211 defined at four corners thereof, such that the top plate 321 has a polygonal shape. The cover 32 also includes a polygonal-shaped peripheral sidewall 322 extending down from a peripheral edge of the top plate 321, and four fixing portions 323 formed at a bottom end of the sidewall 322 at the four corners of the cover 32 where the cutouts 3211 are. Each fixing portion 323 forms a supporting post 325 on a bottom surface thereof, and defines a through hole 324 therein. The through hole 324 spans though the fixing portion 323 including the supporting post 325.

When the airflow generator 20 is mounted to the heat sink 10, the supporting posts 325 of the cover 32 rest on and are supported by the mounting portions 14 of the heat sink 10, with the through holes 324 of the fixing portions 323 of the cover 32 aligned with corresponding mounting holes 15 of the mounting portions 14 of the heat sink 10. Four fixing members 101 such as screws respectively extend through the through holes 324 of the cover 32 and are engaged in the mounting holes 15 of the heat sink 10, thereby fixing the airflow generator 20 on the heat sink 10. The mounting portions 14 of the heat sink 10 are spaced from the fixing portions 323 of the cover 32 by the supporting posts 325 disposed therebetween. In other words, the airflow generator 20 is spaced from the heat sink 10 a predetermined distance.

Referring also to FIG. 5, the cover 32 and the base plate 31 cooperatively define a cavity (not labeled) therebetween, in which airflow-generating units 40 are received and arrayed. Each airflow-generating unit 40 includes a casing 41, and a vibration diaphragm 42 and a driving member 43 received in the casing 41. The casing 41 is cuboid, and has an opening 44 (see FIG. 4) at a bottom side thereof facing the heat sink 10. The base plate 31 is attached to bottom ends of the casings 41 of the airflow-generating units 40. The base plate 31 is a single body of material, and functions as bottom walls of the casings 41 of the airflow-generating units 40, and defines a plurality of orifices 311 therein corresponding to the airflow-generating units 40. Alternatively, the base plate 31 can be divided into a plurality of pieces corresponding to the airflow-generating units 40. Each piece defines an orifice therein, and is attached to a bottom end of the casing 41 of a corresponding airflow-generating unit 40, functioning as a bottom wall of the casing 41 of the airflow-generating unit 40.

The vibration diaphragm 42 of each airflow-generating unit 40 is elastic material, such as rubber, flexible resin or a thin metal sheet. The vibration diaphragm 42 is horizontally mounted in the casing 41. An inner space of the casing 41 is divided into a first chamber 411 and a second chamber 412 by the vibration diaphragm 42. The first chamber 411 and the second chamber 412 are isolated from each other, and are located at top and bottom sides of the vibration diaphragm 42, respectively. The second chamber 412 communicates with the exterior via one corresponding orifice 311 of the base plate 31.

The driving member 43 is adapted for vibrating the vibration diaphragm 42 up and down. In this embodiment, the driving member 43 is a piezoelectric element (hereinafter indicated also by numeral 43). The piezoelectric element 43 is attached to a middle portion of the vibration diaphragm 42 so as to vibrate substantially perpendicular to the vibration diaphragm 42 when an alternating voltage is applied to the piezoelectric element 43. The piezoelectric element 43 is made of piezoelectric ceramic. Through holes (not labeled) are defined in two opposite of the sidewalls 322 of the cover 32 and in sidewalls of the casings 41, for extension of wires 430 therethrough to electrically connect the piezoelectric elements 43 on the vibration diaphragms 42 of the airflow-generating units 40 with an external power supply (not shown).

In operation of the heat dissipation apparatus 100, the external power supply provides an alternating voltage to the piezoelectric element 43 of each airflow-generating unit 40 via the corresponding wire 430. As a result of the reverse piezoelectric effect, the piezoelectric element 43 produces alternating expansion and retraction, vibrating the vibration diaphragm 42 up and down. When the piezoelectric element 43 vibrates the vibration diaphragm 42 downwardly, the vibration diaphragm 42 compresses the air inside the second chamber 412 and drives the air towards the corresponding orifice 311 of the base plate 31, generating airflow from the orifice 311 towards the corresponding air passages 13 of the heat sink 10. The airflow along the air passages 13 of the heat sink 10 removes heat present in the fins 12.

Referring to FIGS. 6-8, an airflow-generating process of each airflow-generating unit 40 in one vibrating period is as follows:

The airflow-generating process is divided into a first stage, a second stage and a third stage. In the first stage, the external power supply provides a negative/positive voltage to the piezoelectric element 43 via the wire 430, and the piezoelectric element 43 drives the vibration diaphragm 42 towards the base plate 31. The air inside the second chamber 412 is compressed by the vibration diaphragm 42 and flows towards the corresponding orifice 311 of the base plate 31. Referring to FIG. 6, when the vibration diaphragm 42 moves from an originally horizontal position to a curved position indicated by broken lines A, a first airflow 102 is generated from the corresponding orifice 311 of the base plate 31 towards the corresponding air passages 13 of the heat sink 10. The first airflow 102 along the air passages 13 of the heat sink 10 results in heat exchange from the fins 12 to the air, and the heat of the fins 12 is thereby removed.

In the second stage of the airflow-generating process, the negative/positive voltage supplied to the piezoelectric element 43 is inverted to a positive/negative voltage, such that the piezoelectric element 43 drives the vibration diaphragm 42 away from the base plate 31. Referring to FIG. 7, when the vibration diaphragm 42 returns from the curved position indicated by broken lines A (see FIG. 6) back to the horizontal position, the air outside the casing 41 and around the corresponding orifice 311 is drawn into the air passages 13 of the heat sink 10, generating a second airflow 103 along the air passages 13 of the heat sink 10, at a flow rate about ten times that of the first airflow 102.

In the third stage of the airflow-generating process, the vibration diaphragm 42, as shown in FIG. 8, continues to move farther way from the base plate 31 until it reaches the curved position indicated by broken line B. During this stage, the volume of the second chamber 412 is expanded, such that cool air (indicated by arrows 33) outside the casing 41 and around the corresponding orifice 311 of the base plate 31 is drawn into the second chamber 412 of the casing 41. Then the positive/negative voltage supplied to the piezoelectric element 43 is inverted to the negative/positive voltage, and the first stage of the airflow-generating process begins again.

In each airflow-generating unit 40, under the alternating voltage, the piezoelectric element 43 vibrates the vibration diaphragm 42 to periodically compress the air inside the second chamber 412 of the casing 41, generating airflow from the orifice 311 towards the air passages 13 of the heat sink 10. In addition, by supplying alternating voltages of different frequencies, the flow rate of the airflow generated by the airflow-generating unit 40 can be adjusted to meet different cooling requirements.

In summary, in the heat dissipation apparatus 100, the heat transferred to the fins 12 of the heat sink 10 is dissipated from the fins 12 by the operation of the airflow generator 20. The number of airflow-generating units 40 of the airflow generator 20 can be chosen to meet the cooling requirements of a particular application. Further, no motor or impeller of a fan is used in the heat dissipation apparatus 100. Thus the heat dissipation apparatus 100 can have a small size and quiet operation.

Referring to FIG. 9, a heat dissipation apparatus 100a according to a second exemplary embodiment of the present disclosure is shown. The heat dissipation apparatus 100a includes the above-described heat sink 10, and an airflow generator 20a mounted on the heat sink 10. The airflow generator 20a includes the above-described shell 30, and a plurality of airflow-generating units 40a arranged in the shell 30. The difference between each airflow-generating unit 40a and each airflow-generating unit 40 of the heat dissipation apparatus 100 lies in a driving member 43a of the airflow-generating unit 40a.

In this embodiment, the driving member 43a is received in the first chamber 411 of the casing 41. The driving member 43a includes a movable magnet 431 attached to a middle of a top surface of the vibration diaphragm 42, and a stationary magnet 433 attached to an inner surface of a top wall of the casing 41. The movable magnet 431 and the stationary magnet 433 face each other, and are spaced apart from each other.

The movable magnet 431 of the driving member 43a is an electromagnet, and includes a thin iron core 4311 and a wire coil 4312 disposed around the iron core 4311. The iron core 4311 is made of a material which can be easily magnetized and demagnetized, such as soft iron or silicon steel. The wire coil 4312 is attached on the vibration diaphragm 42 and surrounds and is spaced from the iron core 4311. Alternatively, the wire coil 4312 can be directly wound on and around the iron core 4311. When the airflow-generating units 40a are arranged in the shell 30, the wire coils 4312 of the movable magnets 431 of the airflow-generating units 40a are connected to each other in series via electric wires (not shown), and are connected to an external power supply (not shown).

In operation of each airflow-generating unit 40a, the external power supply provides an alternating voltage to the wire coil 4312 of the movable magnet 431 of the driving member 43a. When current travels through the wire coil 4312 of the movable magnet 431 of the driving member 43a, the iron core 4311 of the movable magnet 431 is magnetized to create a larger magnetic field that extends into the space around the iron core 4311. The polarity of the magnetized movable magnet 431 is determined by the direction of the current through the wire coil 4312. The direction of the current through the wire coil 4312 is periodically alternated, so that the polarity of the magnetized movable magnet 431 is correspondingly periodically inverted. Accordingly, the magnetized movable magnet 431 and the stationary magnet 433 of the driving member 43a mutually attract or repel each alternately, vibrating the vibration diaphragm 42 up and down. When the movable magnet 431 of the driving member 43a vibrates the vibration diaphragm 42 downwardly, the vibration diaphragm 42 compresses the air inside the second chamber 412 and drives the air towards the corresponding orifice 311 of the base plate 31, generating airflow from the orifice 311 of the base plate 31 towards the corresponding air passages 13 of the heat sink 10. The airflow along the air passages 13 of the heat sink 10 removes heat present in the corresponding fins 12.

When the alternating voltage is supplied to the iron core 4311 of the movable magnet 431 of the driving member 43a of each airflow-generating unit 40a, airflow is generated according to substantially the same process as shown in FIGS. 6-8.

In each airflow-generating unit 40a, under the alternating voltage, the driving member 43a vibrates the vibration diaphragm 42 to periodically compress the air inside the second chamber 412 of the casing 41, thereby periodically generating airflow from orifice 311 towards the air passages 13 of the heat sink 10. By supplying alternating voltages of different frequencies, the flow rate of the airflow generated by the airflow-generating unit 40a can be adjusted to meet different cooling requirements.

Alternatively, the positions of the movable magnet 431 and the stationary magnet 433 of the driving member 43a can be exchanged.

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 defining an inner space therein, the casing comprising a bottom wall defining an orifice therein; a vibration diaphragm arranged in the casing, the vibration diaphragm dividing the inner space of the casing into a first chamber and a second chamber isolated from each other, the second chamber communicating with an exterior of the casing via the orifice of the bottom wall of the casing; and a driving member received in the casing, capable of vibrating the vibration diaphragm in directions substantially perpendicular to the vibration diaphragm when alternating voltage is applied to the driving member, wherein when the driving member vibrates the vibration diaphragm towards the bottom wall of the casing, the vibration diaphragm compresses the air inside the second chamber of the casing and drives the air towards the orifice, generating an airflow from the orifice to the exterior of the casing.

2. The airflow generator of claim 1, wherein the driving member comprises a piezoelectric element attached to the vibration diaphragm.

3. The airflow generator of claim 1, wherein the driving member comprises a movable magnet attached to the vibration diaphragm, and a stationary magnet attached to a top wall of the casing facing the vibration diaphragm, one of the movable magnet and the stationary magnet is a permanent magnet, and the other one of the movable magnet and the stationary magnet is an electromagnet.

4. The airflow generator of claim 3, wherein the movable magnet is an electromagnet, and the stationary magnet is a permanent magnet.

5. The airflow generator of claim 4, wherein the movable magnet comprises a movable iron core attached to the vibration diaphragm and a wire coil disposed around the iron core.

6. The airflow generator of claim 1, further comprising a cover, in which the at least one airflow-generating unit is mounted.

7. The airflow generator of claim 1, wherein the airflow generator comprises a plurality of the airflow-generating units, and the bottom walls of the casings of the airflow-generating units are integrally formed together as a single body of material.

8. A heat dissipation apparatus, comprising:

a heat sink defining a plurality of air passages therein; and

an airflow generator arranged on the heat sink, the airflow generator comprising a plurality of airflow-generating units arranged in an array, each of the airflow-generating units comprising: a casing comprising a bottom wall adjacent to the heat sink; a vibration diaphragm arranged in the casing, the vibration diaphragm dividing an inner space of the casing into a first chamber and a second chamber isolated from each other, the second chamber being located nearer to the heat sink and communicating with an exterior of the casing via an orifice defined in the bottom wall; and a driving member received in the casing, capable of vibrating the vibration diaphragm in directions substantially perpendicular to the vibration diaphragm when alternating voltage is applied to the driving member, wherein when the driving member vibrates the vibration diaphragm towards the bottom wall of the casing, the vibration diaphragm compresses the air inside the second chamber of the casing and drives the air towards the orifice, generating an airflow from the orifice to at least one of the air passages of the heat sink.

9. The heat dissipation apparatus of claim 8, wherein the driving member comprises a piezoelectric element attached to the vibration diaphragm.

10. The heat dissipation apparatus of claim 8, wherein the driving member comprises a movable magnet attached to the vibration diaphragm, and a stationary magnet attached to a wall of the casing facing the vibration diaphragm, one of the movable magnet and the stationary magnet is a permanent magnet, and the other one of the movable magnet and the stationary magnet is an electromagnet.

11. The heat dissipation apparatus of claim 10, wherein the movable magnet is an electromagnet, and the stationary magnet is a permanent magnet.

12. The heat dissipation apparatus of claim 11, wherein the movable magnet comprises a movable iron core attached to the vibration diaphragm and a wire coil disposed around the iron core.

13. The heat dissipation apparatus of claim 8, further comprising a cover, in which the airflow-generating units are mounted.

14. The heat dissipation apparatus of claim 13, wherein the cover comprises a top plate and a sidewall extending down from a peripheral edge of the top plate.

15. The heat dissipation apparatus of claim 14, wherein the heat sink comprises a base and a plurality of spaced fins formed on the base, and the air passages are defined between adjacent fins.

16. The heat dissipation apparatus of claim 15, wherein the heat sink comprises a plurality of mounting portions, the cover has a plurality of fixing portions corresponding to the mounting portions of the heat sink, and the mounting portions of the heat sink are spaced from the fixing portions of the cover by a plurality of supporting posts disposed therebetween.

17. The heat dissipation apparatus of claim 8, wherein the bottom walls of the casings of the airflow-generating units are integrally formed as a single piece.

18. An airflow generator, comprising:

a shell comprising a base plate and a cover connected to the base plate, the cover and the base plate cooperatively defining a cavity therebetween, the base plate defining a plurality of orifices therein; and

a plurality of airflow-generating units arranged in the cavity and located corresponding to the orifices of the base plate, each of the airflow-generating units comprising: a casing defining an inner space therein; a vibration diaphragm arranged in the casing, the vibration diaphragm dividing the inner space of the casing into a first chamber and a second chamber isolated from each other, the second chamber being located adjacent to the base plate and communicating with an exterior of the casing via a corresponding orifice of the base plate; and a driving member received in the casing, capable of vibrating the vibration diaphragm in directions substantially perpendicular to the vibration diaphragm when alternating voltage is applied to the driving member, wherein when the driving member vibrates the vibration diaphragm towards the bottom wall of the casing, the vibration diaphragm compresses the air inside the second chamber of the casing and drives the air towards the corresponding orifice, generating an airflow from the corresponding orifice to the exterior of the casing.

19. The airflow generator of claim 18, wherein the driving member comprises a piezoelectric element attached to the vibration diaphragm.

20. The airflow generator of claim 18, wherein the driving member comprises a movable magnet attached to the vibration diaphragm, and a stationary magnet attached to a wall of the casing facing the vibration diaphragm, one of the movable magnet and the stationary magnet is a permanent magnet, and the other one of the movable magnet and the stationary magnet is an electromagnet.