Abstract:
A mounting device for mounting a first element onto a second element includes a plurality of fastening elements; each of the fastening elements includes a connecting member defining a clasping groove therein, and a guiding portion adjacent to the clasping groove; a ring-shaped clipping member snaps in the clasping groove of the connecting member after moving over the guiding portion to be expanded; a fixing member is coupled to the connecting member for sandwiching the first element and the second element therebetween; a resilient member adapts for sandwiching between the connecting member and the first element to providing resilient force to urge the first element toward the second element.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to a heat dissipating apparatus, and particularly to a mounting device for the heat dissipating apparatus.  
       DESCRIPTION OF RELATED ART  
       [0002]     A heat dissipating apparatus always includes a circuit board with an electric component mounted thereon, a thermal module for dissipating heat generated by the electric component, and a plurality of mounting elements for mounting the thermal module onto the circuit board.  
         [0003]     Each of the mounting elements usually includes a bolt defining an annular groove at a middle portion thereof, a coil spring disposed around the bolt, a ring-like fastener capable of being snapped in the groove, and a screw nut threadedly engaging with a screwed end portion of the bolt.  
         [0004]     The fasteners are made of metal with good resiliency. Each of the fasteners radially defines a through slit. In assembly of the heat dissipating apparatus, the fasteners are expanded radially outwardly by a fixture to surround grooves of the bolts; then the expanding force exerted on the fasteners by the fixture is released so that the fasteners snap in the grooves of the bolts, thereby pre-assembling the bolts to the thermal module. The bolts are then screwed with the screw nuts respectively to mount the pre-assembled thermal module to the circuit board.  
         [0005]     During the pre-assembling of the bolts and fasteners to the thermal module, since there is no mechanism formed in the bolts which can reliably ensure the snapping of the fasters into the grooves of the bolts, the fasteners may be mounted to the screwed end portions of the bolts if the fasteners are not aligned with the grooves. When this happens, the fasteners could separate from the bolts during transportation of the pre-assembled thermal module. Without the fasteners snapped in the grooves, the thermal module can not be securely mounted on the circuit board, which results in that the thermal module cannot have an intimate contact with the electric component. Furthermore, the fixture for radially expanding the fasteners has a complicated structure and accordingly a high cost.  
       SUMMARY OF INVENTION  
       [0006]     According to a preferred embodiment of the present invention, a mounting device for mounting a first element onto a second element, includes a plurality of fastening elements. Each of the fastening elements includes a connecting member defining a clasping groove therein, and a guiding portion adjacent to the clasping groove and between the clasping groove and a bottom end of the connecting member. The guiding portion has a diameter larger than that of the bottom end. The guiding portion has a circumferential surface tapering toward the bottom end of the connecting member. A ring-shaped clipping member snapped in the clasping groove after moving over the guiding portion from the bottom end of the connecting member. A fixing member is coupled to the bottom end of the connecting member for sandwiching the first element and the second element therebetween. A resilient member adapts for sandwiching between the connecting member and the first element to providing resilient force to urge the first element toward the second element so that the first element can have an intimate contact with the second element.  
         [0007]     Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which: 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0008]      FIG. 1  is an exploded isometric view of a heat dissipating apparatus according to a preferred embodiment of the present invention;  
         [0009]      FIG. 2  is an enlarged view of a circled portion of  FIG. 1  indicated by II;  
         [0010]      FIG. 3 a  cross-sectional view taken along line III-III of  FIG. 1 , showing a pre-assembled thermal module, and  FIG. 4  is a view similar to  FIG. 3 , showing the pre-assembled thermal module mounted to a circuit board having an electronic component thereon, wherein connecting members and fixing members of the heat dissipating apparatus are assembled at an initial position;  
         [0011]      FIG. 5  is a view similar to  FIG. 4 , with the connecting members and the fixing members are assembled at a final position; and  
         [0012]      FIG. 6  is a cross-sectional view of a heat dissipating apparatus according to another embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0013]     Referring to  FIG. 1 , a heat dissipating apparatus  10  according to a preferred embodiment of the present invention includes a circuit board  20  with a heat generating electronic component  21  (referring to  FIG. 4 ) mounted thereon, a thermal module  30  for timely removing heat generated by the electronic component  21 , and a mounting device composed of a plurality of fastening elements  40  for fastening the thermal module  30  to the circuit board  20 .  
         [0014]     The thermal module  30  includes a supporting plate  31 , a heat sink  32  and a heat pipe  33  (referring to  FIG. 3 ). The heat sink  32  and the heat pipe  33  are located on two opposite sides of the supporting plate  31 , respectively. A heat dissipating fan  34  is located adjacent to the heat sink  32 . The supporting plate  31  defines a plurality of through holes  35  at different positions thereof for receiving the fastening elements  40  therein. The heat pipe  33  thermally connects the electronic component  21  with the heat sink  32  for transferring heat from the electronic component  21  to the heat sink  32 . The fan  34  is for driving an airflow through the heat sink  32  thereby to take the heat away from the heat sink  32 .  
         [0015]     Each of the fastening elements  40  includes a columned connecting member  41 , a resilient member  42  for being disposed around the connecting member  41 , a ring-like clipping member  43  for being snapped to a lower part of the connecting member  41 , and a fixing member  44  for being screwed to an end portion of the connecting member  41 .  
         [0016]     Also referring to  FIG. 2 , the connecting member  41  includes a main portion  411 , a head portion  412  positioned at a top end of the main portion  411 , and a threaded fixing portion  413  formed at a bottom end of the main portion  411 . The head portion  412  has a diameter larger than that of the main portion  411 . The main portion  411  includes a ring-like flange  411   a  adjacent to the head portion  412  for engaging a top end of the resilient member  42 , thereby preventing the resilient member  42  from falling off the connecting member  41 . The main portion  411  also defines an annular clasping groove  411   b  near the fixing portion  413  for snapping of the clipping member  43  in the groove  411   b . A diameter of the main portion  411  is greater than a diameter of the fixing portion  413 , so that a part of the main portion  411  extends beyond the fixing portion  413  along a radial direction. A cone-shaped guiding portion  414  is formed on the main portion  411  between the groove  411   b  and the fixing portion  413 . The guiding portion  414  has a diameter larger than that of the fixing portion  413 . The guiding portion  414  is so configured that a diameter thereof is gradually increased along an axial direction of the connecting member  41  from the fixing portion  413  to the head portion  412 . In other words, the guiding portion  414  has a circumferential surface tapering toward the bottom end of the connecting member  41 .  
         [0017]     The clipping member  43  is made of plastics which has good resilient capability. The clipping member  43  is formed with a ring-shaped configuration with a central hole. The clipping member  43  is sufficiently resilient that its central hole can be expanded to a degree, which enables the clipping member  43  to move over the guiding portion  414  without being damaged. The clipping member  43  may also be formed with a radially through slit to increase the resiliency of the clipping member  43 , thereby to facilitate the mounting of the clipping member  43  to the connecting member  41 .  
         [0018]     The fixing member  44  is attached in a bottom face of the circuit board  20 , and forms a threaded hole  441  therein for engagingly receiving the fixing portion  413  of the connecting member  41 .  
         [0019]     The resilient member  42  such as a coil spring (first embodiment,  FIGS. 1-5 ), or a resilient metal plate spring (second embodiment,  FIG. 6 ), is for providing resilient force to push the head portion  412  of the connecting member  41  and, accordingly, the circuit board  20  and the electronic component  21  to move upwardly, as the resilient members  42  is sandwiched between the head portion  412  and the supporting plate  31  of the thermal module  30  after the clipping member  43  is snapped in the clasping groove  411   b , and the fixing portion  413  is engagingly received in the fixing member  44 . The upward movement of the electronic component  21  by the resilient member  42  ensures that the electronic component  21  has an intimate contact with the thermal module  30 .  
         [0020]     Referring to  FIG. 3  to  FIG. 5 , in assembly of the heat dissipating apparatus  10 , the coil springs  42  are mounted to surround the main portions  411  of the connecting members  41  with the top ends of the coil springs  42  engaging with the flanges  411   a , respectively. The connecting members  41  of the fastening elements  40  are placed in the corresponding through holes  35  of the thermal module  30 . The head portions  412  of the fastening elements  40  are then pressed toward the supporting plate  31  of the thermal module  30  until the clasping grooves  411   b  extend upwardly beyond the thermal module  30 . At this position, the coil springs  42  are compressed between the head portions  412  and the supporting plate  31  of the thermal module. Thereafter, the clipping members  43  are mounted to the corresponding connecting members  41  by extending the bottom ends of the connecting members  41  into the central holes of the clipping members  43 , respectively. The clipping members  43  are moved downwardly to run over the guiding portions  414  and finally snap into the grooves  411   b . During moving over the guiding portions  414 , the clipping members  43  are gradually resiliently expanded by the tapered circumferential surfaces of the guiding portions  414  until the clipping members  43  reach and snap into the grooves  411   b , in which the clipping members  43  return to their original dimensions and configurations. Thus, the fastening elements  40 , the thermal module  30  and the clipping members  43  are assembled together with the clipping members  43  abutting against a bottom surface of the supporting plate  31  of the thermal module  30  under the resilient force exerted by the coil springs  42  ( FIG. 3 ). Now particularly referring to  FIG. 4 , the fixing portions  413  are then turned over and brought to threadedly engaging in the threaded holes  441  of the fixing members  44  by rotating the head portions  412 . The heat portions  412  are continuously rotated until fixing portions  413  completely threadedly engage in the threaded holes  441 , the clipping members  43  contact with the circuit board  20  and the coil springs  42  are further compressed ( FIG. 5 ). Thus, the circuit board  20  and the supporting plate  31  of the thermal module  30  are sandwiched between the head portions  412  of the connecting members  41  and the fixing members  44 , with the electronic component  21  intimately contacting with a bottom surface of the thermal module  30 .  
         [0021]     In the present invention, the clipping member  43  is first pressed on the guiding portion  414  and then snapped in the corresponding clasping groove  411   b  after leaving the guiding portion  414 . The clipping member  43  is expanded by the guiding portion  414  on the connecting member  41 , rather than by a fixture for mounting the clipping member  43  to the connecting member  41 ; thus, the fixture can have a simple structure and accordingly a low cost. Furthermore, since the clipping member  43  is mounted to the connecting member  41  along an axial direction thereof, not a radial direction thereof like the conventional art, the clipping member  43  can be more easily, reliably and correctly positioned to snap into the groove  411   b , without the disadvantage of the conventional art that the clipping member may engage in the fixing portion  413 . Finally, the mounting of the clipping member  43  to the groove  411   b  of the connecting member  41  in accordance with the present invention can be more quickly completed than the conventional art.  
         [0022]     Referring to  FIG. 6 , another embodiment of the present invention is shown. The difference of this embodiment over the previous embodiment is as follows. The bottom ends of the connecting members  41 &amp;apos; of the fastening elements  40 &amp;apos; are coupled to the fixing members  44 &amp;apos; by riveting, not by threaded engagement of the previous embodiment. Furthermore, the resilient members  42 &amp;apos; in this embodiment are resilient metal plate springs instead of the coil springs.  
         [0023]     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, 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 invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.