Patent Abstract:
A clip is disclosed which is capable of applying significant retention force via a rotatable cam arm while being easily removable due to the cam arm and a separate removal arm. A method of using the clip is also disclosed which uses the advantages of the clip, particularly in the context of computer design and construction.

Full Description:
This application is a division of application Ser. No. 10/021,812, filed Dec. 14, 2001, now U.S. Pat. No. 6,688,431. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to the field of mechanical fasteners, and particularly to retention clips, specifically heatsink retention clips used to anchor heatsinks to heatsink retainers. 
     BACKGROUND OF THE INVENTION 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     In the field of computer design, processing chips, which perform the computational functions of a computer, typically generate substantial amounts of heat. This heat must be dispersed from around the chip to prevent malfunctions. To accomplish this, heatsinks are typically associated with the chips to provide a structure with high surface area to disperse the heat. As processing chips have grown both faster and hotter, heatsinks have grown proportionately larger and heavier. For example, current heatsinks may weigh more than a half pound to achieve the desired heat dissipating effect. 
     Retention clips are typically used to secure the heatsink to a heatsink retainer which positions the heatsink relative to the heat generating chip. As heatsinks have grown larger and heavier, the retention clips must in turn be stronger to avoid shifting. If a retention clip is too weak to secure the heatsink during shipping, the heatsink may pull loose, allowing the processing chip to come unseated due to their interface. 
     In addition to strong retention clips, however, there is also a need to make the clips easy to install and remove. Current clips must either be removed with a screwdriver or other tool or with a release tab or other mechanism requiring the application of significant force even after the release of any locking mechanism. Additionally, the use of release tabs and levers typically result in retention clips which enlarge or exceed the heatsink envelope, thereby increasing the footprint of the assembly and limiting the height of nearby elements. Such clips are difficult for factory personnel to remove not only due to the need to use a tool within a confined space to effect removal but also due to the force necessary to remove the stronger clips. Ideally, a retention clip would require low installation force, would possess high retention force, and would be easily removable. 
     SUMMARY OF THE INVENTION 
     The following passage is intended only to provide a brief summary of limited aspects of the present inventions and should not be construed as encompassing all necessary elements or steps of the inventions. The present invention is related generally to overcoming the deficiencies inherent in previous designs by allowing easy insertion and removal of a retention clip while providing adequate retention force. This aim is accomplished by providing designs comprising a simple release generally in the form of a pinchable release mechanism. Additionally methodologies are provided which include the act of using a pinchable release mechanism to effect the release of a heatsink retention clip. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
         FIG. 1  is a cutaway view of a idealized computer system including an exploded view of a heatsink assembly; 
         FIG. 2  is a side view of a heatsink retention clip; 
         FIG. 3  is a perspective view of a heatsink retention clip in the locked position; and 
         FIG. 4  is a perspective view of a heatsink retention clip in the unlocked position. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     It will be appreciated that the present invention can take many forms and embodiments. Some embodiments of the invention are described so as to give an understanding of the invention. It is not intended, however, that the embodiments of the present invention that are described in this specification should limit the invention. 
     Turning now to the drawings and referring initially to  FIG. 1 , there is depicted a cutaway, perspective view of an exemplary computer system  10 . Computer system  10  comprises a chassis  14  which in turn is comprised of a number of chassis walls  18 . 
     In addition, computer system  10  comprises a motherboard  22 . Motherboard  22 , in turn, comprises a board substrate  26  and components such as central processing unit  30 , and memory components  34 . Disposed about CPU  30  on motherboard  22  is a heatsink retainer  50 . Mass storage device  38  also resides within the chassis and is connected to motherboard  22 . In addition, computer system  10  comprises input and output devices such as monitor  42  and keyboard  46 . 
     In the illustrated embodiment, heatsink retainer  50  possesses clip engagements  62  along the edges and generally disposed about the corners. As depicted, each clip engagement  62  is configured to receive a hooked member  94  comprising a part of a retainer clip  58 . Alternatively clip engagement  62  may be configured as a projection such that the projection fits into a cutout window comprising a part of retainer clip  58 . 
     In computer system  10 , heatsink  54  is conformably engaged with retainer  50  such that the bottom of heatsink  54  is in contact with CPU  30 . In the preferred embodiment, two retainer clips  58  are disposed along heatsink upper faces  78  and securely engage with clip engagements  62  of retainer  50  via hooked members  94 . As depicted in  FIG. 1 , retainer clip  58  further comprises a cam arm  102  and a removal arm  98  which provide for easy engagement and removal of retainer clip  58  in the limited space of chassis  14 . 
     As depicted, the heatsink assembly, comprising heatsink retainer  50  and heatsink  54 , defines a three-dimensional spatial envelope. As illustrated, the addition of retainer clip  58  does not substantially increase the size or change the shape of the envelope. In an exemplary embodiment, the footprint of the envelope is generally square and remains square even after the addition of retainer clip  58 . 
       FIG. 2  depicts an embodiment of the retainer clip of the present application. Retainer clip  58  is shown to comprise a clip body  82  of generally elongated nature. Clip body  82  comprises a clip top surface  114  and a clip bottom surface  118 . Each end of clip body  82  comprises a retaining arm, a first retaining arm  86  and a second retaining arm  90 , projecting downward relative to bottom surface  118 . On the distal portion of first retaining arm  86  and second retaining arm  90  are hooked members  94  which serve to engage clip engagement  62 . Alternatively, first retaining arm  86  and second retaining arm  90  may comprise cut out windows on their distal portion which engage conforming projections instead of clip engagements  62 . 
     Additionally, clip body  82  comprises a removal arm  98  on one end projecting upward relative to top surface  114 . Removal arm  98  may be a looped structure when clip body  82 , first retaining arm  86 , second retaining arm  90 , and removal arm  98  all comprise a single unitary piece. 
     Retainer clip  58  also comprises a cam arm  102  generally centered along clip body  82 . Cam arm  102  has an arm body  130  connected to two arm runners  134  such that each is located on a different side of arm body  130  and configured to span the width of clip body  82 . Each runner  134  comprises a hinge hole  138  configured to receive a corresponding hinge pin  142  projecting from the side of clip body  82 . The coupling on hinge pin  142  and hinge hole  138  allow cam arm  102  to partially rotate relative to clip body  82 . Each runner  134  further comprises two pair of aligned, inward facing protrusions a pair of unlock protrusions  146  and a pair of lock protrusions  150 . Both unlock protrusions  146  and lock protrusions  150  act to hinder, but not prevent, the free rotation of cam arm  102  relative to clip body  82  effectively preventing rotation of cam arm  102  absent the application of some minimal level of force. 
     Cam arm  102  may further comprise a lifting member  106  which is configured such that, when cam arm  102  is rotated generally perpendicular to clip body  82 , lifting member is angled slightly away from clip body  82 . Cam arm  102  also comprises rotation stop  122  configured to prevent rotation of cam arm  102  when cam arm is generally perpendicular to clip body  82 . 
     In the embodiment illustrated in  FIG. 2 , cam arm  102  is connected to clip body  82  by hinge hole  138  and hinge pin  142  such that the rotation of cam arm  102  is toward removal arm  98 . Rotation stop  122 , however, prevents rotation toward removal arm  98  past a point which is generally parallel to removal arm  98  and generally perpendicular to clip body  82 . 
     Referring now to  FIG. 3 , Retainer clip  58  is shown from a birdseye perspective in a locked configuration which would be typical of normal operation in the preferred embodiment. Longitudinal axis  126  is shown for reference running in the direction of clip body  82 . In the locked configuration cam arm  102  is rotated such that it is generally parallel to clip body  82 . In this position, lock protrusions  150  act to impede the free rotation of cam arm  102  from the locked position. A force exceeding some minimum required force must be applied to cam arm  102  to overcome the resistance of lock protrusions  150  when locking or unlocking the cam arm. Additionally, as depicted lifting member  106  and rotation stop  122  each are angled away from top surface  114  of clip body  82  when cam arm  102  is in the locked position. 
     As is also depicted in  FIG. 3 , in the locked position, runners  134  extend downward along the sides of clip body  82  in the same direction as the retaining arms  86 ,  90 . Thus, referring back to  FIG. 1 , in the locked position, runners  134  exert force on heatsink upperface  78  and thereby securely hold heatsink  54  against CPU  30 . In the locked position, clip bottom surface  118  is therefore not in contact with heatsink upper face  78 . In this manner, the mechanical force generated by hinged cam arm  102  in conjunction with the engagement of hooked members  94  with clip engagements  62  allows greater force to be applied in securing heatsink  54  than would be possible in the absence of cam arm  102 . 
     Referring now to  FIG. 4 , retainer clip  58  is shown from a birdseye perspective in an unlocked configuration which would be typical of removal or insertion in the preferred embodiment. To effect insertion of retainer clip  58 , referring also to  FIG. 1  for context, it will be presumed that heatsink  54  is disposed in an unsecured manner upon heatsink retainer  50 . Retainer clip  58 , while in an unlocked configuration, is then placed upon heatsink  54  such that clip bottom surface  118  rests on heatsink upper face  78 . 
     To achieve this position a downward force will be applied to retainer clip  58  so that hooked members  94  can overcome the resistance provided by clip engagements  62 . The rounded edges of hooked members  94  help to facilitate sliding past clip engagements  62 . Alternatively, a pinching force my be applied to removal arm  98  and parallel cam arm  102  to provide a bend to clip body  82  and to thereby further separate the retaining arms  86 ,  90 . In this manner, hooked members  94  may more easily be pushed past clip engagements  62 . When hooked member  94  are in position relative to clip engagements  62  and when clip bottom surface  118  is resting upon heatsink upper face  78 , cam arm  102  may be rotated to a locked position to secure heatsink  54  to CPU  30 . To effect this rotation of cam arm  102 , the resistances provided by unlock protrusions  146  and lock protrusion  150  must be overcome with a sufficient force. 
     To effect removal of retainer clip  58  from a locked position cam arm  102  is rotated from the locked position, generally parallel to clip body  82  to the unlocked position, roughly parallel to removal arm  98 . This is done by overcoming the resistances provided by lock protrusions  150  and unlock protrusions  146 . Once in the unlocked position, runners  134  will no longer be securing heatsink  54  to retainer  50 , and hooked members  94  should be disengaged from clip engagements  62 . If hooked members  94  are not disengaged from clip engagements  62  a downward force may be applied to retainer clip  58  to achieve this disengagement. 
     Next a pinching force is applied using removal arm  98  and now parallel cam arm  102 . The pinching arm effects a distortion of clip body  82  which acts to further separate the retaining arms  86 ,  90 . The separation of the retaining arms  86 ,  90 , and therefore the separation of hooked members  94 , allows for easy lifting of hooked members  94  past clip engagements  62 . Once hooked members  94  are clear of clip engagements  62 , retaining clip  58  may be easily and completely removed from the heatsink assembly. As noted above, an alternative embodiment would replace hooked member  94  with windowed cutouts and clip engagements  62  with fitted projections. However, operation of the retainer clip  58  would remain the same in this alternative embodiment. 
     Due to the presence of the partially rotatable cam arm  102  and removal arm  98 , removal of retainer clip  58  can be accomplished without the use of any tools, such as a screwdriver or other prying instrument. The pinch removal system combined with the mechanically efficient hinged cam arm allows the use of a more powerful retainer clip, a necessity due to the increasing weight of heatsinks, while still allowing easy insertion and removal. In one exemplary embodiment, the retainer clip of this application is capable of applying the 70 lbs. of force to securely hold a heatsink, thereby preventing a processor from pulling out in a drop test. 
     While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Technology Classification (CPC): 8