Abstract:
A fastener, for assembling a fan to a bracket, includes a shaft, and an expanding head extending from an end of the shaft. The shaft has a bulge formed at an opposite end thereof. A handle extends from the bulge of the shaft. The handle is used for facilitating an operator to manipulate the fastener to secure the fan and the bracket together. By pulling the handle of the fastener, the shaft of the fastener extends through the fan and the bracket to reach a position where the head and the bulge of the shaft of the fastener tightly sandwich the fan and the bracket therebetween.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to a fastener assembly for fastening two components together, and more particularly to a fan fastener fastening a fan to a fan holder of a heat sink for dissipating heat generated by an electronic device. 
   DESCRIPTION OF RELATED ART 
   It is well known that, during operation of a computer, electronic devices such as central processing units (CPUs) frequently generate large amounts of heat. The heat must be quickly removed from the electronic device to prevent it from becoming unstable or being damaged. Typically, a heat sink is attached to an outer surface of the electronic device to absorb heat from the electronic device. The heat absorbed by the heat sink is then dissipated to ambient air. Generally, in order to improve heat dissipation efficiency of the heat sink, a fan assembly is attached to the heat sink to provide forced airflow to the heat sink. 
   Conventionally, a fan is fastened to a fan holder such as a bracket of a heat sink directly via a plurality of screws. However, it is time-consuming and laborious to screw the screws to the fan holder through the fan in order to combine the fan to the fan holder together. Furthermore, a fixation by the screws cannot effectively absorb vibration made by the fan when it rotates, whereby a noise is generated by the fan in operation, which is required to be further reduced. 
   What is needed, therefore, is a fastener fastening a fan to a fan holder of a heat sink conveniently; furthermore, the fastener can absorb vibration of the fan in operation thereby to reduce noise level generated by the fan during operation thereof. 
   SUMMARY OF INVENTION 
   A fastener in accordance with an embodiment of the present invention, for assembling a fan to a bracket (fan holder) of a heat sink, comprises a shaft. The shaft has an expanding head formed at an end thereof and a bulge formed at an opposite end thereof. A handle extends from the bulge of the shaft for facilitating operation of an operator to combine the fan and bracket together. 
   A method in accordance with an embodiment of the present invention for fastening the fan to the bracket includes the steps of:
     a) providing a plurality of fasteners, each of the fasteners comprising a shaft and a handle extending from a first end of the shaft;   b) inserting the fasteners into corresponding fixing holes of the fan and then the bracket until the handles of the fasteners project a distance beyond the fixing holes of the bracket;   c) pulling the handles of the fasteners to extend the first ends of the shafts of the fasteners to reach a position beyond the fixing holes of the bracket;   d) releasing the pulling force on the handles of the fasteners whereby the fan and bracket are tightly sandwiched between an expanding head and a bulge formed on each of the shafts of the fasteners, and then cutting the handles away from the fasteners.   

   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 fan assembly and a heat sink in accordance with a preferred embodiment of the present invention; 
       FIG. 2  shows a fastener of the fan assembly of  FIG. 1 ; 
       FIG. 3  is a partially assembled view of the fan assembly of  FIG. 1 ; 
       FIG. 4  is an assembled view of the fan assembly of  FIG. 1  from a rear aspect, with a handle of the fan fastener being cut away. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1 , a fan assembly and a heat sink  10  in accordance with a preferred embodiment of the present invention is shown. The fan assembly is attached to the heat sink  10  to provide forced airflow to the heat sink  10 . The fan assembly comprises a fan  40 , a bracket (fan holder)  20  for attached the fan  40  to the heat sink  10 , a gasket  30  between the bracket  20  and the fan  40 , a plurality of fasteners  50  fastening the fan  40  to the bracket  20 . 
   The heat sink  10  comprises a base  11  and a plurality of fins  13  arranged on the base  11 . The base  11  extends two thin steps  112  from two opposite lateral sides thereof, respectively. The two steps  112  define two fixing holes  114  at front ends thereof, respectively, for fixing the bracket  20  to the heat sink  10 . 
   The bracket  20  comprises a substantially rectangular faceplate  21  and four sidewalls  22  extending from four sides of the faceplate  21 . The faceplate  21  defines an opening  211  in a center thereof. Four fixing apertures  212  are defined in four corners of the faceplate  21 , respectively. Two fastening ears  221  each having a fastening hole  222  defined therein oppositely extend from two lateral ones of the sidewalls  22 , respectively, for fastening the bracket  20  to the heat sink  10 . Two screws (not shown) are used to extend through the fastening holes  222  and screw into the fixing holes  114 , thereby securing the bracket  20  to the heat sink  10 , after the fan  40 , the gasket  30  and the bracket  20  are assembled together. 
   The fan  40  is substantially rectangular, and comprises a frame  41  and a fan blade unit (not labeled) located in the frame  41 . The fan blade unit is used to generate a forced airflow when it rotates. Four through holes  411  are defined in four corners of the frame  41 , respectively, for accommodating the fasteners  50  therein. 
   The gasket  30  is substantially rectangular corresponding to the fan  40  and comprises three interconnecting beams  31  which define an opening  33  thereamong. Four through apertures  313  are defined in four corners of the gasket  30  corresponding to the through holes  411  of the frame  41  of the fan  40  and the fixing apertures  212  of the faceplate  21  of the bracket  20 . 
   Referring also to  FIG. 2 , each of the fan fasteners  50  has good elasticity and is integrally molded from elastomer such as plastics by for example plastics injection molding. Each fan fastener  50  has a pin-like shape, and comprises a shaft  53 , an expanding head  51  extending from a front end of the shaft  53 , and an elongate handle  59  extending from an opposite, rear end of the shaft  53 . The shaft  53  has the opposite, rear end thereof tapered to form a bulge  57  thereat. The bulge  57  is formed around a circumference of the opposite, rear end of the shaft  53 . A slot  55  is circumferentially defined in the shaft  53  just in front of the bulge  57  and between the bulge  57  and the expanding head  51 . The head  51 , the shaft  53  and the handle  59  are coaxial. A diameter of the head  51  is larger than that of the through hole  411  of the frame  41  of the fan  40 . A diameter of the handle  59  is smaller than that of the through hole  411  and the fixing aperture  212  of the faceplate  21  of the bracket  20 . A diameter of the bulge  57  is larger than that of the fixing aperture  212  of the faceplate  21 . A length between the head  51  and the bulge  57  of the shaft  53  is slightly smaller than a total length of thicknesses of the fan  40 , the gasket  30  and the faceplate  21  of the bracket  20 . 
   Referring also to  FIGS. 3 and 4 , in assembly, the fasteners  50  are inserted into corresponding through holes  411  of the frame  41  of the fan  40  by extending the handles  59  through the through holes  411 , then the through apertures  313  of the gasket  30  and the fixing apertures  212  until the handles  59  of the fan fasteners  50  project a distance rearwards beyond the fixing apertures  212  of the bracket  20 . The handles  59  of the fan fasteners  50  are then pulled rearwards to reach a position wherein the slots  55  are located behind the through holes  411  of the fan  40  and the through apertures  313  of the gasket  30 . The bracket  20  is pushed toward the fan  40  and the fan fasteners  50  are pulled to expand to thereby make the bulges  55  project beyond the fixing apertures  212  of the faceplate  21  of the bracket  20 . Then, the pulling force on the handles  59  of the fan fasteners  50  is released, and the fan fasteners  50  shrink. Therefore, the bulges  55  tightly abut against a rear face of the faceplate  21  toward the fan  40 , while the expanding heads  51  of the fan fasteners  50  securely abut against a front face of the frame  41  of the fan  40 . The faceplate  21  of the bracket  20  defining the fixing apertures  212  is received in the slots  55  of the fasteners  50 . Therefore, the fan  40 , the gasket  30  and the bracket  20  are tightly sandwiched between the expanding heads  51  and the bulges  57  of the fasteners  50  and are intimately assembled together thereby. Thereafter, the handles  59  of the fan fasteners  50  are cut away. Finally, the bracket  20  with the fan  40  attached thereon is retained to a front side of the heat sink  10  via the screws (not shown) extended through the fastening holes  222  of the ears  221  of the bracket  20  and screwed in the fixing holes  114  of the base  11  of the heat sink  10 . The handles  59  are formed for facilitating an operator to pull the fasteners  50  through the frame  41  of the fan  40 , the gasket  30  and the bracket  20  to reach the position that the frame  41 , the gasket  30  and the bracket  20  are securely combined together. 
   According to the embodiment of present invention, the fan  40 , the gasket  30  and the bracket  20  are assembled only by first pushing and then pulling the fasteners  50  through the fan  40 , the gasket  30  and the bracket  20 ; thus, the assembly thereof is quite easily and simple. 
   Additionally, the fasteners  50  have good flexibility, which provide elastic securing force to retain the fan  40  and the bracket  20  together. Furthermore, the elastic fasteners  50  buffer vibration of the fan  40  during operation thereof; thus, noises level generated by operation the fan  40  can be lowered. Additionally, the gasket  30  between the fan  40  and the bracket  20  is also made of elastic material, thereby further absorbing vibration of the fan  40  during operation thereof. 
   It is believed that the present embodiment 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.