Axial heat-dissipating device

[0001] This application claims priority of Taiwanese Application No. 091132959, filed on Nov. 8, 2002.

[0002] 1. Field of the Invention

[0003] The invention relates to a heat-dissipating device, more particularly to an axial heat-dissipating device capable of quick heat dissipation.

[0004] 2. Description of the Related Art

[0005] FIG. 1 shows a conventional heat-dissipating device adapted to be mounted on top of a heat-generating component 12 that is disposed on a circuit board 11 of an electronic device. The heat-generating component 12 can be a central processing unit, an integrated circuit, or the like. The heat-dissipating device includes an aluminum heat-dissipating fin unit 13 disposed in thermal contact with the heat-generating component 12, and a fan 14 oriented toward the fin unit 13. The fin unit 13 has a bottom portion provided with a heat-conducting plate 15 that is formed from copper and that facilitates the transfer of heat generated by the heat-generating component 12 to the fin unit 13. However, such a conventional heat-dissipating device has the following setbacks:

[0006] 1. Although aluminum and copper have quite high temperature coefficients of conductivity, their combined heat-dissipating effect is not very satisfactory, resulting in that the surface temperature of the heat-generating component 12 remains higher than that of the fin unit 13. That is, currents of air blown by the fan 14 can only disperse the heat around the fin unit 13, and cannot reach the surface of the heat-generating component 12 to dissipate the heat of the heat-generating component 12.

[0007] 2. In view of the aforesaid, when heat gradually accumulates on the surface of the heat-generating component 12, since the conventional heat-dissipating device cannot effectively dissipate the high heat, the operation of the heat-generating component 12 will be affected, which may result in shutdown of or even damage to the electronic device.

[0008] Therefore, the object of the present invention is to provide an axial heat-dissipating device that is capable of quick heat dissipation.

[0009] Accordingly, an axial heat-dissipating device of the present invention includes:

[0010] a heat-dissipating unit including an upright heat-transfer member having a lower end adapted to be disposed on a heat-generating source, a plurality of angularly spaced apart heat-dissipating fins provided on the heat-transfer member, and a hollow shell body that is disposed to surround the heat-dissipating fins, the shell body having a top end portion and a lower end portion which is formed with at least one radial air inlet that permits flow of air into the shell body; and

[0011] a fan unit mounted on the top end portion of the shell body and operable so as to draw hot air out of the shell body.

[0012] Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:

[0013] FIG. 1 is a schematic plan view of a conventional heat-dissipating device;

[0014] FIG. 2 is a perspective view of the first preferred embodiment of an axial heat-dissipating device according to the present invention;

[0015] FIG. 3 is an exploded perspective view of the first preferred embodiment;

[0016] FIG. 4 is another exploded perspective view of the first preferred embodiment, which is taken from a different angle;

[0017] FIG. 5 is a sectional view to illustrate the first preferred embodiment in part;

[0018] FIG. 6 is an exploded perspective view of the second preferred embodiment of an axial heat-dissipating device according to the present invention;

[0019] FIG. 7 is a sectional view to illustrate the third preferred embodiment of an axial heat-dissipating device according to the present invention in part;

[0020] FIG. 8 is an exploded sectional view of the third preferred embodiment in part, illustrating that a base member, a heat-guiding post and heat-dissipating fins are connected integrally;

[0021] FIG. 9 is a sectional view to illustrate the fourth preferred embodiment of an axial heat-dissipating device according to the present invention in part, showing integral connection among a base member, a heat-guiding post, and heat-dissipating fins;

[0022] FIG. 10 is a cross-sectional view to illustrate the fourth preferred embodiment in part; and

[0023] FIG. 11 is a sectional view to illustrate the fifth preferred embodiment of an axial heat-dissipating device according to the present invention in part, showing integral connection among a base member, a heat-guiding post, heat-dissipating fins, and a shell body.

[0024] Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.

[0025] Referring to FIGS. 2 to 5, the first preferred embodiment of an axial heat-dissipating device 2 according to the present invention is shown to be adapted for mounting on a heat-generating source 3 (see FIG. 5), which can be a central processing unit, an integrated circuit, or the like. In this embodiment, the heat-generating source 3 is a central processing unit. As shown, the axial heat-dissipating device 2 includes a heat-dissipating unit 4 and a fan unit 6. The heat-dissipating unit 4 includes a heat-transfer member 40 having a lower end adapted to be disposed on the heat-generating source 3, a plurality of angularly spaced apart heat-dissipating fins 400 provided on the heat-transfer member 40, and a hollow shell body 100 that is disposed to surround the heat-dissipating fins 400. The heat-transfer member 40 includes a base member 8 adapted to be disposed on the heat-generating source 3, and a heat-guiding post 91 that extends uprightly from the base member 8. In this embodiment, the base member 8 is circular, but may have any other suitable geometric shape. The base member 8 has a bottom surface 81 adapted to be disposed on the heat-generating source 3, and an upwardly converging top surface 82. The top surface 82 is formed with at least one lower cavity 83 in a central portion thereof. In this embodiment, four lower cavities 83 are provided.

[0026] The heat-guiding post 91 is formed with an upper cavity 911 that is registered with the lower cavity 83 and that cooperates with the lower cavity 83 to form a heat-dissipating cavity 110. In this embodiment, four upper cavities 911 are provided to be respectively registered with the four lower cavities 83 so as to form four heat-dissipating cavities 110 (see FIG. 5), respectively.

[0027] The heat-dissipating fins 400 extend from the heat-guiding post 91 in radial outward directions. Each adjacent pair of the heat-dissipating fins 400 define a channel 400 therebetween. Each of the heat-dissipating fins 400 has a curved lower edge 401 that complements and that is in contact with the converging top surface 82 of the base member 8.

[0028] The shell body 100 has a lower end portion formed with a bottom opening 101 and a plurality of radial air inlets 103 that are in fluid communication with the channels 400 so as to permit flow of ambient air into the shell body 100 and through the channels 400, and a top end portion formed with a top opening 102 and a plurality of radial retaining holes 104. The air inlets 103 are also adapted to receive fasteners (not shown) for positioning the axial heat-dissipating device 2.

[0029] The fan unit 6 is mounted removably on the top end portion of the shell body 100 and is operable so as to draw hot air out of the shell body 100 through the top opening 102. The fan unit 6 includes an annular frame 62, an impeller member 61 connected to the annular frame 62, and a plurality of snap fasteners 63 extending downwardly from a bottom end of the annular frame 62 so as to engage the retaining holes 104, thereby positioning the fan unit 6 on the shell body 100. Preferably, the fan unit 6 is an exhaust fan.

[0030] The heat-dissipating unit 4 further includes a thermal conductor 5 received in the heat-dissipating cavity 110. The thermal conductor 5 may be one of a heat-conducting rod and a heat-conducting pipe. In this embodiment, four thermal conductors 5 are received respectively in the four heat-dissipating cavities 110, and each of the thermal conductors 5 preferably has an outer surface coated with a heat-conducting paste 7. It is noted that a superconducting heat-conducting rod can achieve quick conduction of heat from the heat-generating source 3.

[0031] Alternatively, each of the heat-dissipating cavities 110 may be filled with a thermally conductive material or may have an inner wall surface coated with a thermally conductive material. In another alternative, the heat-dissipating cavities 110 are vacuumed to form sealed vacuum chambers which are filled with a thermally conductive material, such as water, methanol, acetone, ammonia, nitrogen, sodium, lithium, or mixtures thereof, or with a superconductor material. It is noted that the term filled as used herein can be construed to mean completely filled or partially filled.

[0032] It is further noted that each of the heat-dissipating fins 400 is preferably coated with a thermally conductive material 10.

[0033] In use, when the working temperature of the heat-generating source 3 rises, the heat-dissipating cavities 110 having the thermal conductors 5 or the thermally conductive material therein transfer the heat quickly from the heat-generating source 3 upwardly and across the heat-dissipating fins 400 that provide an extensive heat-dissipating area. In addition, the fan unit 6 draws relatively cold ambient air through the air inlets 103 into the shell body 100. Due to the configuration of the upwardly converging top surface 82 of the base member 8, the air is drawn quickly upward through the channels 400 to carry away the air around the heat-dissipating unit 4. The hot air is then discharged to the ambient through the fan unit 6. Thus, the preferred embodiment provides an excellent heat-dissipating effect. It is noted that the heat-dissipating fins 400 can be configured to be spiral in shape for faster air currents.

[0034] With reference to FIG. 6, the second preferred embodiment of an axial heat-dissipating device 2 according to the present invention further comprises a thermoelectric generator 120 mounted on a top end of the heat-transfer member 40, and a heat-dissipating fin member 130 mounted on the top end of the heat-transfer member 40. Furthermore, the top end portion of the shell body 100 confines a recess 100. The heat-dissipating fin member 130 includes a plurality of radial fins that define channels 400, and is disposed in the recess 100 such that the channels 400 are in fluid communication with the channels 400 and such that the shell body 100 surrounds the heat-dissipating fins 400 and the heat-dissipating fin member 130. The fan unit 6 is mounted on top of the heat-dissipating fin member 130. The thermoelectric generator 120 in this embodiment is a thermocouple that has a hot side 121 in contact with an upper end of the heat-guiding post 91 and a cold side in contact with a bottom central portion 132 of the heat-dissipating fin member 130. A heat-conducting paste can be disposed between the hot side 121 and the upper end of the heat-guiding post 91 and between the cold side 122 and the bottom central portion 132. In addition, the thermoelectric generator 120 is coupled electrically to the fan unit 6 by an electric cable 140 for supplying electric power thereto. When heat is conducted from the heat-generating source 3 through the heat-guiding post 91, a temperature difference is created between the hot and cold sides 121, 122 of the thermoelectric generator 120, thereby resulting in production of an electric current (direct current). When the temperature difference exceeds 50 degrees Celsius, the electric current thus produced is sufficient to actuate the fan unit 6 to draw ambient air into the shell body 100 through the air inlets 103 and out of the shell body 100 so as to help carry away the heat around the heat-dissipating unit 4. Two or more thermoelectric generators 120 can be connected in series to increase the output current, if desired. As such, the thermoelectric generator 120 not only provides a power source to help dissipate heat, it can also reduce power consumption of the electronic system, such as a computer system, incorporating the second preferred embodiment of this invention.

[0035] With reference to FIGS. 7 and 8, the third preferred embodiment of an axial heat-dissipating device according to the present invention is shown to be substantially similar to the first preferred embodiment. The major differences therebetween reside in that the base member 8, the heat-guiding post 91 and the heat-dissipating fins 400 are connected integrally such that the heat-dissipating cavity 110 that is constituted by the upper cavity 911 of the heat-guiding post 91 and the lower cavity 83 of the base member 8 extends continuously through the heat-guiding post 91 and the base member 8. The heat-dissipating cavity 110 preferably has an inner wall surface coated with a thermally conductive material 10.

[0036] With reference to FIGS. 9 and 10, the fourth preferred embodiment of an axial heat-dissipating device according to the present invention is shown to be substantially similar to the third preferred embodiment. The difference therebetween resides mainly in that each of the heat-dissipating fins 400 confines a receiving space 402 that is communicated with the upper cavity 911 and the lower cavity 83 so as to cooperatively constitute the heat-dissipating cavity 110. As in the previous embodiments, the heat-dissipating cavity 110 preferably has an inner wall surface coated with a thermally conductive material 10.

[0037] With reference to FIG. 11, the fifth preferred embodiment of an axial heat-dissipating device according to the present invention is shown to be substantially similar to the fourth preferred embodiment. The difference therebetween resides mainly in that the base member 8, the heat-guiding post 91, the heat-dissipating fins 400, and the shell body 100 are connected integrally. As in the previous embodiments, the heat-dissipating cavity 110 is preferably filled with a thermally conductive material 10.

[0038] In view of the foregoing, it is apparent that the present invention is capable of overcoming the aforesaid drawbacks associated with the prior art, and can provide an enhanced heat-dissipating effect.

[0039] While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.