Patent Publication Number: US-2007119567-A1

Title: Heat dissipation device

Description:
FIELD OF THE INVENTION  
      The present invention generally relates to a heat dissipation device, and more particularly to a heat dissipation device for use with electronic elements.  
     DESCRIPTION OF RELATED ART  
      With the development of large scale integrated circuit technology in the information industry, personal computers are becoming more and more popular. As we know, the central processing unit (CPU) is the core unit of a computer system, and accordingly plays an important role in maintaining the integrity and performance of the computer system. With the increasing demand for higher processing power in computers, the CPUs are now operating at higher speeds and thus generate larger amounts of heat. The heat must be quickly and efficiently removed from the CPU; otherwise, the temperature of the CPU will increase until above its critical operating temperature, thus affecting the performance and reliability of the computer. Therefore, newer microprocessors with enhanced functions and a more complex design require an increased heat dissipation so as to timely dissipate the heat generated thereby. Generally, the heat is dissipated by a heat dissipation assembly being maintained in thermal contact with the CPU.  
      Conventionally, the heat dissipation assembly includes a heat sink and a fan mounted on the heat sink. The heat sink commonly includes a base and a plurality of fins thereon. The base thermally contacts with a heat source element and transfers the heat generated by the heat source element to the fins. A forced airflow generated by the fan flows over the fins to enhance heat dissipation of the heat sink, and to ensure a steady operation for the heat source element.  
      At present, the fan is mounted to the heat sink, usually by means of screws. However, in this method, a mounting tool such as a screw driver is required to mount the fan to or detach the fan from the heat sink, which can be cumbersome and time-consuming.  
      Locking the fan by means of a fan holder is another method of combining the fan to the heat sink. The fan defines a groove therein and the fan holder has a hook thereon. The fan is attached to the heat sink by the hook of the fan holder engaging in the groove of the fan. However, in this method, the fan is mounted to the fan holder in a self-locking manner where the fan is permanently secured to the fan holder and cannot be detached therefrom for replacement or repair.  
      Accordingly, it is desirable to provide a heat dissipation device wherein at least one of the aforementioned disadvantages may be overcome or at least alleviated.  
     SUMMARY OF THE INVENTION  
      A heat dissipation device in accordance with a preferred embodiment of the present invention comprises a heat sink, a cooling fan mounted on the heat sink, and a fan holder disposed between the heat sink and the cooling fan. The fan holder comprises a square shaped frame defining an opening therein. At least one flexible fastener is set on each of a pair of opposite sides of the frame; the at least one flexible fastener is configured to have an elasticity allowing it to deform outwardly. At least one clamping arm is set on one of the other pair of opposite sides of the frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Many aspects of the present heat dissipation device 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 heat dissipation device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, in which:  
       FIG. 1  is an assembled, isometric view of a heat dissipation device in accordance with an embodiment of the present invention;  
       FIG. 2  is an exploded view of the heat dissipation device of  FIG. 1 ;  
       FIG. 3  is an assembled, isometric view of a heat dissipation device in accordance with another embodiment of the present invention; and  
       FIG. 4  is an exploded view of the heat dissipation device of  FIG. 3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to  FIG. 1 , a heat dissipation device in accordance with an embodiment of the present invention comprises a heat sink  10 , a cooling fan  30  and a fan holder  20  arranged therebetween to mount the cooling fan  30  to the heat sink  10 .  
      Referring to  FIG. 2 , the heat sink  10  comprises a base  12  and a plurality of fins  14  arranged on the base  12 . The fins  14  are formed integrally with the base  12  and extend vertically upwardly from the base  12 . The fins  14  are spaced apart from each other so that a channel  16  is formed between every two adjacent fins  14 . A cutout (not labeled) is defined in a middle portion of each of the fins  14 , so that these cutouts cooperatively form an elongated groove  18  perpendicular to the channels  16 . A clip (not shown) is located in the groove  18  to attach the heat sink  10  to a heat source element (not shown) such as a central processing unit (CPU) of a computer system. Two outmost fins  140  of the heat sink  10  are higher than the main fins  14  located between the higher fins  140 . A slot  19  is defined at a top portion of each of the higher fins  140  and communicates with the groove  18 .  
      The cooling fan  30  comprises a frame  32  and a rotor  34  located therein. A square-shaped top flange  322  and a square-shaped bottom flange  324  are formed at top and bottom sides of the frame  32 , respectively. Four columns  326  are formed at four corners of the frame  32  to connect the top flange  322  with the bottom flange  324 .  
      The fan holder  20 , which is disposed between the cooling fan  30  and the heat sink  10 , comprises a square shaped frame  22 . The frame  22  comprises a pair of first crossbeams  40  at two opposite sides thereof and a pair of second crossbeams  50  at the other two opposite sides thereof. The first and second crossbeams  40 ,  50  connect in series together and accordingly an opening  24  is defined in a center of the frame  22 , for providing access for an airflow from the cooling fan  30  towards the heat sink  10 .  
      An extension portion  42  is formed on each of the first crossbeams  40  extending downwardly towards the heat sink  10 . An upwardly protruding, arc-shaped bulge  54  is formed at a middle portion of each of the second crossbeams  50 . An engagement block  52  extends from each of the second crossbeams  50 , adjacent to the bulge  54 , the size and shape of the engagement block  52  corresponding to that of the slots  19 . The fan holder  20  and the heat sink  10  are combined together by the blocks  52  engaging in the slots  19 .  
      Two spaced clamping arms  44  are formed extending upwardly from two ends of one of the first crossbeams  40 . Specifically, the clamping arms  44  are located near two corners of the frame  22 , respectively. Each clamping arm  44  comprises a perpendicular portion  46  extending upwardly from the frame  22  and a horizontal portion  48  extending inwardly from a distal free end of the perpendicular portion  46 . Thus, a receiving space (not labeled) is formed between the clamping arm  44  and the frame  22  so as to locate an outer peripheral portion of the bottom flange  324  of the fan  30 .  
      A flexible fastener  56  is formed extending upwardly from one end of each of the second crossbeams  50  remote from the corresponding clamping arm  44 . In other words, the fasteners  56  are located near the other two corners of the frame  22 . The flexible fastener  56  comprises a locking portion  562  being in the form of an inner hook and a handle portion  564 . The height of the locking portion  562  corresponds to that of the bottom flange  324  of the fan  30 . The handle portion  564  inclines upwardly and outwardly from a distal end of the locking portion  562 . In assembly, the handle portions  564  may be operated by hand. The flexible fasteners  56  are accordingly splayed outwardly due to deformation thereof so that the cooling fan  30  is fixed to the fan holder  20 .  
      The frame  22 , the clamping arms  44  and the flexible fasteners  56  are preferably made of plastic material, and are formed integrally so as to simplify the manufacturing process.  
      In assembly, the cooling fan  30  is disposed at a slant so that the outer peripheral portion of the bottom flange  324  can be received in the receiving spaces formed by the clamping arms  44 . The handle portions  564  of the flexible fasteners  56  can be deformed outwardly, either by hand or by other means, so as to allow the cooling fan  30  to be pushed downwardly entering into engagement with the fasteners  56 . After the handle portions  564  are released, the flexible fasteners  56  return to their original positions, and the locking portions  562  engage with the outer peripheral portion of the bottom flange  324  of the cooling fan  30 , thereby firmly grasping the cooling fan  30  on the fan holder  20 . The clamping arms  44  and the flexible fasteners  56  abut against three edges of the bottom flange  324  of the cooling fan  30 , thus restricting the cooling fan  30  from movement relative to the fan holder  20 . In addition, the arc-shaped bulges  54  on the frame  22  are provided to abut against a bottom face (not labeled) of the cooling fan  30  and make up assembly tolerance between the cooling fan  30  and the fan holder  20 , so as to combine the cooling fan  30  and the fan holder  20  more tightly and restrict the cooling fan  30  from moving in the axial direction of the cooling fan  30 . Thus, the cooling fan  30  is assembled to the fan holder  20 .  
      Thereafter, the cooling fan  30  and the fan holder  20  are placed on the heat sink  10 . The blocks  52  of fan holder  20  engage with the outmost fins  140  in the slots  19 . The extension portions  42  of the fan holder  20  abut against a top surface defined by the main fins  14 . Thus the assembly of the heat dissipation device is completed. In use, the heat dissipation device is mounted on the heat source element by the clip located in the groove  18 .  
      To detach the heat dissipation device, the handle portions  564  of the flexible fasteners  56  are brought to splay outwardly so that the cooling fan  30  can be taken away from the fan holder  20 .  
      A heat dissipation device in accordance with another embodiment of the present invention is shown in  FIG. 3  and  FIG. 4 . The heat dissipation device, as in the first embodiment of the present invention, comprises a heat sink  10 , a cooling fan  30  and a fan holder  20   a . The fan holder  20   a  comprises a pair of clamping arms  44   a  located near two corners of the frame  22   a  and a pair of flexible fasteners  56  located near the other two corners of the frame  22   a . The difference is that each of the clamping arms  44   a  comprises a perpendicular portion (not labeled) extending upwardly from the frame  22   a  and a flexible finger  442   a  extending inwardly from a free distal end of the perpendicular portion. A hook  444   a  is formed at a free distal end of the flexible finger  442   a . In assembly, the hook  444   a  catches the corresponding column  326  of the cooling fan  30 , as shown in  FIG. 3 .  
      In the above embodiments, the positions and the quantities of the clamping arms  44 ,  44   a  and the flexible fasteners  56  can be changed if needed. It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.