Abstract:
A heat dissipation device comprises a seat for absorbing heat from a heat generating device. At least a heat pipe has a first section thereof thermally combined to the seat, and two second sections thereof extending from the first section and remotely from the seat. Pluralities of heat sinks are located on the seat. Each of the pluralities of heat sinks has a base and a plurality of fins integrally extending from the base and is made of aluminum extrusion. The bases of the heat sinks thermally sandwich the two second sections of the at least a heat pipe therebetween. At least one of the bases of the heat sinks is angled or perpendicular to the seat.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a heat dissipation device for use in removing heat from an electronic device, and more particularly to a heat dissipation device incorporating heat pipes for improving heat dissipation capacity thereof. 
   DESCRIPTION OF RELATED ART 
   During operation of an electronic device such as a computer central processing unit (CPU), a large amount of heat is often produced. The heat must be quickly removed from the electronic device to prevent it from becoming unstable or being damaged. Typically, a heat dissipation device is attached to an outer surface of the electronic device to absorb heat from the electronic device. The heat absorbed by the heat dissipation device is then dissipated to ambient air. 
   Conventionally, a heat dissipation device comprises a solid metal base attached on the electronic device, and a plurality of fins arranged on the base. The base is intimately attached on the electronic device thereby absorbing the heat generated by the electronic device. Most of the heat accumulated at the base is transferred firstly to the fins and then dissipated from the fins to ambient air. However, since the electronics technology continues to advance, the amount of heat generated by powerful state-of-the-art electronic devices is enormously increased. Many conventional heat dissipation devices are no longer able to efficiently remove heat from these electronic devices. 
   In order to overcome the above disadvantages of the heat dissipation device, one type of heat dissipation device used for the electronic device includes a heat pipe which can quickly transfer heat from a position to another position of the heat dissipation device. A heat pipe is a vacuum-sealed pipe that is filled with a phase changeable fluid, usually being a liquid, such as water, alcohol, acetone and so on, and has an inner wall thereof covered with a capillary configuration. As the electronic device heats up, a hot section of the heat pipe, which is usually called an evaporating section and located close to the electronic device, also heats up. The liquid in the evaporating section of the heat pipe evaporates and the resultant vapor reaches a cool section of the heat pipe, which is usually called a condensing section, and condenses therein. Then the condensed liquid flows to the evaporating section along the capillary configuration of the heat pipe. This evaporating/condensing cycle repeats and since the heat pipe transfers heat so efficiently, the evaporating section is kept at or near the same temperature as the condensing section of the heat pipe. Consequentially, heat-transfer capability of the heat dissipation device including such a heat pipe is improved greatly. 
   Typically, a heat dissipation device illustrated as follows is used widely. The heat dissipation device comprises a base for contacting with a heat generating electronic device, two U-shaped heat pipes each having a first section combined to the base, and a plurality of fins stacked on two second sections perpendicularly extending from two ends of the first section of each heat pipe. Each fin is made by stamping a metal sheet and defines through holes receiving the second sections of the heat pipes therein. Generally, the second sections of the heat pipes are mechanically and thermally secured in the through holes of the fins by soldering. In use, the base of the heat dissipation device contacts the heat generating electronic device and absorbs heat therefrom. The heat in the base is then absorbed by the first sections of the heat pipe, and subsequently reaches the fins via the second sections of the heat pipes; finally, the heat in the fins is dissipated to ambient air. However, each of the fins is made by stamping the metal sheet, and then stacked on the second sections of the heat pipes one by one, which is laborious for manufacture of the heat dissipation device, and results in high cost of the heat dissipation device. Furthermore, the fins contact the heat pipes only in the holes thereof, and thus, contacting area between each fin and the heat pipe is considerably small; what is worse is that the fins can not effectually thermally contact the heat pipe; consequently, the heat in the heat pipes can not duly and adequately reaches the fins to be dissipated. As a result, heat dissipation efficiency of such heat dissipation device is still not good enough to meet functions and abilities of the up-to-date electronic device. Therefore the heat dissipation device needs to be improved. 
   What is needed, therefore, is a heat dissipation device with heat pipes having improved heat dissipation capability and low cost. 
   SUMMARY OF INVENTION 
   A heat dissipation device in accordance with a preferred embodiment of the present invention comprises a seat for absorbing heat from a heat generating device. At least a heat pipe has a first section thereof thermally combined to the seat, and two second sections thereof extending from the first section and remotely from the seat. Pluralities of heat sinks are located on the seat. Each of the pluralities of heat sinks has a base and a plurality of fins integrally extending from the base. The base and the fins are integrally formed as one piece by metal extrusion. The bases of the heat sinks thermally sandwich the two second sections of the at least a heat pipe therebetween. At least one of the bases of the heat sinks is angled or perpendicular to the seat. 
   Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which: 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is an exploded, isometric view of a heat dissipation device in accordance with a preferred embodiment of the present invention; 
       FIG. 2  is a partially assembled view of  FIG. 1 ; 
       FIG. 3  is a further partially assembled view of  FIG. 1 ; 
       FIG. 4  is a still further partially assembled view of  FIG. 1 ; and 
       FIG. 5  is an assembled view of  FIG. 1 . 
   

   DETAILED DESCRIPTION 
   Referring to  FIGS. 1 and 2 , a heat dissipation device according to a preferred embodiment of the present invention for dissipating heat generated by an electronic device (not shown) located on a printed circuit board (not shown) is shown. The heat dissipation device comprises a seat  10 , two heat pipes  20  thermally contacting the seat  10 , and a plurality of heat sinks located on the seat  10 . 
   The seat  10  comprises a first base plate  111  and a second base plate  12 . Both of the first base plate  111  and the second base plate  12  have great heat conductivity. The first base plate  11  is substantially pentagonal, and has a bottom face for contacting to the electronic device and a top face defining two parallel first grooves  111  therein. The second base plate  12  is substantially rectangular and defines two parallel second grooves  121  corresponding to the first grooves  111  of the first base plate  11 . The first and second grooves  111 ,  121  corporately define two channels (not labeled) for receiving the heat pipes  20  therein. Two fixing members  13  are fixed on the top face of the first plate  11  and located at two opposite sides of the second base plate  12 . Each of the fixing members  13  has two fixing arms  133  oppositely extending outwardly away the first base plate  11 . Each of the arms  133  defines a fixing hole (not labeled) adjacent a distal end thereof. A fastener  134  such as a screw, bolt or the like is fitted in the fixing hole. A top face of the second base plate  12  and a top face of the fixing member  13  corporately define a plane for arranging the heat sinks thereon. 
   The two heat pipes  20  are substantially parallel to each other and arranged on the seat  10 . Each of the two heat pipes  20  is substantially U-shaped and comprises a first section  201  and two substantially parallel second sections  202  perpendicularly extending from two ends of the first section  201 . A round corner is formed at each joint of the first and second sections  201 ,  202  of each heat pipe  20 . The first sections  201  of the two heat pipes  20  are fitted in the channels of the seat  10 , respectively. The second sections  202  of the two heat pipes  20  extend perpendicularly away from the seat  10 . 
   Referring also to  FIGS. 3-5 , the plurality of heat sinks comprises a first heat sink  40 , two second heat sinks  50 , and two third heat sinks  60 . The first, second, third heat sinks  40 ,  50 ,  60  are all formed by aluminum extrusion. Aluminum extrusion is performed by forcibly pushing a one-piece stock of aluminum under a raised temperature through a mold. The first, second, third heat sinks  40 ,  50 ,  60  respectively comprise bases  410 ,  510 ,  610  and pluralities of fins  420 ,  520 ,  620  integrally extending perpendicularly from the bases  410 ,  510 ,  610 , respectively. The base  410  of the first heat sink  40  has a bottom face contacting to the top plane of the seat  10 . The second sections  202  of the two heat pipes  20  are positioned at two opposite sides of the first heat sink  40 . Corresponding to the corners of the two heat pipes  20 , the two opposite sides of the first heat sink  40  define two cutouts  411  therein, respectively, for eliminating interference with the two heat pipes  20 . The second, third heat sinks  50 ,  60  respectively define two parallel grooves  511 ,  611  in non-fin faces of the bases  510 ,  610  thereof. The bases  510 ,  610  of the second and third heat sinks  50 ,  60  face to each other and thermally contact each other. The grooves  511 ,  611  corporately define two positioning channels (not labeled) between two thermally connected second and third heat sinks  50 ,  60 . The second sections  202  of the two heat pipes  20  are fitted in the channels. The two second heat sinks  50  are sandwiched between the second sections  202  of the two heat pipes  20 . The fins  520  of the second heat sinks  50  contact each other at distal ends thereof. The second heat sinks  50  have two bottom fins  520  contacting a top of the first heat sink  40 . The two second heat sinks  50  are directly mounted on the first heat sink  40 . The third heat sinks  60  are positioned at two opposite sides of the second heat sinks  50 . The third heat sinks  60  have bottom ends thereof resting on the fixing arms  133  of the fixing members  13 . Two slots (not labeled) are respectively defined between the two opposite sides of first heat sink  40  and the bases  610  of the third heat sinks  60 . Thickness of the fins  520 ,  620  are substantial identical, and distances between two adjacent fins  520 ,  620  are also identical; thus, the fins  520 ,  620  of the second, third heat sinks  50 ,  60  align with each other at a horizontal direction. The fins  620  of the two third heat sinks  60  define four vertical spaces  621  corresponding to the fasteners  134  of the fixing members  13 , for preventing interference between the fins  620  and the fasteners  134  to thereby facilitate an operator to manipulate the fasteners  134  to fix the heat dissipation device to the printed circuit board. The fins  420  of the first heat sink  40  extend vertically upwardly from the base  410  thereof. The fins  520  of the second heat sinks  50  extend from the bases  510  thereof in a direction horizontally towards each other. The fins  620  of the third heat sinks  60  extend from the bases  610  thereof in a direction horizontally away from each other. 
   In use, the first base plate  11  of the seat  10  contacts to the electronic device and absorbs heat therefrom. The heat in the first base plate  11  reaches the first sections  201  of the heat pipes  20 , the second base plate  12  and the fixing members  13 . And then the heat reaches the first, second, third heat sinks  40 ,  50 ,  60  via the second base plate  12 , the fixing members  13  and the second sections  202  of the heat pipes  20 . Subsequently, the heat is dissipated to ambient air by the fins  420 ,  520 ,  620 . 
   According to the preferred embodiment of the present invention, the heat sinks  40 ,  50 ,  60  are combined with the heat pipes  20  to improve heat dissipation efficiency of the heat dissipation device. The heat sinks  40 ,  50 ,  60  of the heat dissipation device are formed by aluminum extrusion, which simplifies manufacture of the heat dissipation device and lowers cost of the heat dissipation device. Furthermore, the heat sinks  40 ,  50 ,  60  are combined to the heat pipes  20  via the heat pipes  20  being soldered in the grooves  511 ,  611  of the bases  510 ,  610  of the second, third heat sinks  50 ,  60 , which is easy to realize an intimate and large contact between the heat sinks  50 ,  60  and the heat pipes  20 ; therefore, heat exchange between the heat pipes  20  and heat sinks  50 ,  60  is sufficient and rapid. Therefore, the heat dissipation capacity of the heat dissipation device is improved greatly. 
   In the present invention, it can be easily perceived by those skilled in the art that the two second sections  202  of each heat pipe  20  can be extended from the first section  201  thereof at angle larger than the shown 90, degrees. For such heat pipes, the second and third heat sinks  50 ,  60  are correspondently tilted in respective to the seat  10 . 
   It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.