Abstract:
A hand tightened locking pin using a unique internal cam configuration to lock the pin assembly. The pin assembly includes a sleeve and a locking cam unit. The sleeve includes anti-rotation protrusions that match a keyhole in a first metal plate to prevent rotation of the sleeve. The pin assembly is inserted through the keyhole of the first metal plate and a circular hole in a second metal plate that lies on the first metal plate. When the locking cam unit, which is inside the sleeve, is rotated, a lower portion of the sleeve expands, locking the first and metal plates together. The cam is locked in position by concave shaped ends that mate over bulges in the lower portion of the sleeve. A locked/unlocked indicator on top of the pin assembly indicates when the concave shaped ends are mated with the bulges.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Technical Field  
         [0002]     This invention relates generally to fasteners, and in particular fasteners for connecting two metal plates. Still more particularly, the present invention relates to a locking pin having a cam that expands a lower portion of an outer shell to lock the two metal plates together.  
         [0003]     2. Description of the Related Art  
         [0004]     As with other mechanical, electrical and electromechanical devices, computers are made up of many components that need to be rigidly fastened together, in order to avoid the absurdity of a loose collection of parts lying in a pile. Components such as cases and frames are typically held together with welds, rivets and other permanent fasteners. Other components, particularly internal components, are held together with nonpermanent fasteners that permit the internal components to be removed and/or replaced.  
         [0005]     Internal components such as processor boards, or board support structures, are typically mounted on racks inside the computer. Each rack has mounting flanges with a hole in each flange, as does a frame holding the processor board. To secure the processor board to the rack, a nonpermanent fastener is placed through the aligned holes in the mounting flange of the rack and the processor board, and then the nonpermanent fastener is tightened, thus holding the two flanges together. Examples of such nonpermanent fasteners are nuts and bolts, setscrews, and clips. A problem with nuts and bolts and setscrews is that they require tools to be fastened or removed. A problem with clips is that they are prone to loosen and/or fall out, and often are unable to provide a very tight connection.  
         [0006]     Thus, there is a need for a nonpermanent fastener that can be used without any tools, to fasten parts, and particularly computer parts, together. The fastener should be able to provide a secure, tight and strong connection that does not loosen with vibration over time. Preferably, the fastener should provide a “locked” position when securing two components together, and an “unlocked” position to remove the fastener. To avoid potential electrical shorting problems caused by the fastener being accidentally dropped onto electrical components in the computer, the nonpermanent fastener should be constructed of a material that is electrically non-conducting. The fastener should be color distinctive for both identification and location. The fastener should have a distinct marking visible to the user that indicates whether the fastener is in the locked or unlocked position. Finally, the fastener should provide a tactile and/or audible feedback indicating when the fastener is in the locked position.  
       SUMMARY OF THE INVENTION  
       [0007]     As will be seen, the foregoing invention satisfies the foregoing needs and accomplishes additional objectives. Briefly described, the present invention provides a hand tightened locking pin using a unique internal cam configuration to lock the pin assembly.  
         [0008]     The pin assembly includes a sleeve and a locking cam unit. The sleeve includes anti-rotation protrusions that match a keyhole in a first metal plate to prevent rotation of the sleeve. The pin assembly is inserted through the keyhole of the first metal plate and a circular hole in a second metal plate that lies on the first metal plate. When the locking cam unit, which is inside the sleeve, is rotated, a lower portion of the sleeve expands, locking the first and metal plates together. The cam is locked in position by concave shaped ends that mate over bulges in the lower portion of the sleeve. A locked/unlocked indicator on top of the pin assembly indicates when the concave shaped ends are mated with the bulges, thus locking the two metal plates together.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as the preferred modes of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:  
         [0010]      FIG. 1  depicts an interior or a computer housing;  
         [0011]      FIG. 2   a - b  illustrate lock indicators on a locking pin;  
         [0012]      FIGS. 3   a - c  depict details of a processor board rack being connected to a case mounted bracket inside the computer housing;  
         [0013]      FIGS. 3   d - e  illustrate details of a sleeve component of the locking pin;  
         [0014]      FIGS. 4   a - b  depict additional detail of the sleeve and a locking cam unit that make up the locking pin;  
         [0015]      FIGS. 4   c - d  illustrate additional detail of a rotation limiting pin and channel in the locking pin; and  
         [0016]      FIGS. 5   a - b  depict additional detail of the locking pin in an unlocked ( FIG. 5   a ) and locked ( FIG. 5   b ) position.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]     Referring now to the drawing figures, in which like numerals indicate like elements or steps throughout the several views, the preferred embodiment of the present invention will be described. In general, the present invention provides an improved locking pin having an internal rotatable cam that expands a sleeve, thus locking two sheets of metal when the locking pin is inserted into holes in the sheets of metal and the internal rotatable cam is turned.  
         [0018]     With reference now to  FIG. 1 , there is depicted an interior of a computer housing  102 . Attached to the inside of computer housing  102  is a case mounted bracket  106 . A processor board rack  104 , designed to hold a processor board or support card/board (none shown), has a rack flange  110 , which mates up with a bracket flange  112  of case mounted bracket  106 . A feature of the present invention, a locking pin  108 , couples rack flange  110  to bracket flange  112 , thus attaching processor board rack  104  to case mounted bracket  106 . As will be seen in further detail below, locking pin  108  includes a sleeve  116 , in which a locking cam unit  114  is seated. As depicted in  FIG. 1 , locking pins  108  are in a locked position (which will be discussed in greater detail below), thus firmly coupling the processor board rack  104  to case mounted bracket  106 .  
         [0019]     Referring now to  FIG. 2   a,  additional detail of locking pin  108  is provided. As shown, locking pin  108  has a first locked indicator  202  and a second locked indicator  204 . When locking pin  108  is in a locked position, about which more is described below, first locked indicator  202  and second locked indicator  204  align as shown. When locking pin  108  is in an unlocked position, by rotating locking cam unit as shown in  FIG. 2   b  (either clockwise as shown or counterclockwise depending on the design of locking pin  108 ), the first locked indicator  202  and second locked indicator  204  are no longer aligned. Accordingly, first locked indicator  202  and second locked indicator  204  provide a visual cue to a user indicating whether locking pin  108  is in a locked or unlocked position.  
         [0020]     With reference now to  FIG. 3   a,  processor board rack  104  is shown being removed from case mounted bracket  106  when locking pins  108  are unlocked. Locking pins  108 , and in particular expandable projections  308  are able to slide out of flange circular holes  302  when locking pins  108  are unlocked (allowing expandable projections  308  to be reduced in diameter, as described in further detail below).  
         [0021]     In  FIG. 3   b,  a bracket keyed hole  304  is shown in rack flange  110 . As shown, bracket keyed hole  304  is shaped to prevent a rotation of sleeve  116 , for reasons described below. After processor board rack  104  is decoupled from case mounted bracket  106 , the unlocked locking pins  108  can be slid out of rack flanges  110  as shown.  
         [0022]      FIG. 3   c  provides additional detail of locking pin  108 , an in particular sleeve  116 . As illustrated in  FIG. 3   c  and in a cross-sectional view in  FIG. 3   d,  sleeve  116  has anti-rotation protrusions  306 , which mate in keyed hole ends  310  to prevent a rotation of sleeve  116  when locking cam unit  114  is rotated to lock or unlock locking pin  108 .  
         [0023]      FIG. 3   e  provides additional detail of sleeve  116  as it is inserted or removed through bracketed keyed hole  304  of rack flange  110 . As sleeve  116  is inserted or removed from rack flange  110 , expandable projection  308  is compressed, allowing expandable projection  308  to slide through bracket keyed hole  304 .  
         [0024]     With reference now to  FIG. 3   a,  when sleeve  116  is fully inserted through bracket keyed hole  304  and flange circular hole  302 , expandable projection  308  expands, thus presenting a profile that is wider than flange circular hole  302  to lock sleeve  116  in, and to press rack flange  110  against bracket flange  112 .  
         [0025]     Referring now to  FIG. 4   a,  an exploded view of locking pin  108 , including locking cam unit  114  and sleeve  116 . Note that in a preferred embodiment, sleeve  116  has a retention groove  402  inset into the interior face of a castled perimeter  418 . When locking cam unit  114  is inserted into sleeve  116 , a retention lip  404  on a cam unit disc  412  seats into retention groove  402 , preventing locking cam unit  114  from coming out of sleeve  116  during normal use of locking pin  108 .  
         [0026]     A cam opening  426  passes through the center of sleeve  116 , which affords a passageway for cam  424  and a cam stem  428  to pass through to the interior portion of expandable projection  308 .  
         [0027]     Note that cam  424  of locking cam unit  114  has an ellipse shape  408 , as shown in  FIG. 4   b.  Ellipse shape  408  is so shaped to lock the locking pin  108 , as described further in  FIGS. 5   a - b.  Note also that ellipse shape  408  has concave ends  410 , which prevent locking pin  108  from unlocking, again as described in further detail below.  
         [0028]     Referring to  FIG. 4   c,  a side view of cam unit disc  412  is depicted, to give additional detail of a rotation-limiting pin  414 . Rotation limiting pin  414  seats in a limiting channel  420 , shown in  FIG. 4   d,  which is inset in the mating side  422  of sleeve  116 . As shown, limiting channel  420  preferably subtends 90° of arc, thus allowing locking cam unit  114  to rotate 90° to lock or unlock locking pin  108 . Alternatively, rotation-limiting pin  414  can be attached to mating side  422  and limiting channel  420  can be inset into the underside of cam unit disc  412 .  
         [0029]     With reference now to  FIG. 5   a,  locking pin  108  is illustrated in an unlocked position. As shown, in the unlocked position, cam  424  is oriented within an expandable opening  508  such that cam  424  does not press against expandable projection  308 . That is, when locking pin  108  is in the unlocked position, cam  424  does not press against a cylindrical portion  502 , a conical portion  504 , or a bullet nose  506  of expandable projection  308 . (Note that cylindrical portion  502  is preferably attached in a perpendicular orientation to a base  510  of sleeve  116 .) As such, expandable projection  308  retains a relatively narrow diameter, and does not push against an underside surface of rack flange  110  shown in  FIG. 1 . Furthermore, in the non-expanded configuration, expandable projection  308  allows locking pin to be removed as described above in  FIG. 3   b.  Note that first locked indicator  202  and second locked indicator  204  are not aligned, thus indicating the locking pin is in the unlocked condition.  
         [0030]     Referring now to  FIG. 5   b,  locking pin  108  is depicted in a locked position. In the locked position, cam  424  presses against the interior surface of expandable projection  308 , primarily against the area where cylindrical portion  502  and conical portion  504  meet. This pressure causes the diameter of expandable projection  308  to expand, causing the exterior surface of expandable projection  308  to press against the underside surface of rack flange  110  shown in  FIG. 1 , thus locking together the rack flange  110  and the bracket flange  112 . Note also the alignment of first locked indicator  202  and second locked indicator  204  indicating the locked condition of locking pin  108 .  
         [0031]     Because of the configuration and fit of cam  424 , and particularly concave end  410 , against cam retaining bulge  406 , a tactile “snap” feedback is produced with locking pin  108  locks into the locked position. This “snap” feeling transmitted to the user gives a tactile indication, which augments the visual indication afforded by first locked indicator  202  aligning with second locked indicator  204 , that locking pin  108  is locked.  
         [0032]     In a preferred embodiment, sleeve  116  is a first distinctive color, such as (but not exclusively) yellow, and locking cam unit  114  is a second distinctive color, such as (but not exclusively) blue. This distinctive color-coding provides two advantages. First, they allow the user to quickly spot where the locking pins  108  are located. Second, by being different colors, the user can clearly confirm that the sleeve  116  is not rotating when the locking cam unit  114  is being rotated during the locking or unlocking of locking pin  108 .  
         [0033]     The present invention has been described in relation to particular embodiments that are intended in all respects to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. For example, although the inventive locking pin has been depicted as securing a processor board rack, the locking pin is also useful in directly securing (fastening) a board or any similar mechanical support structure. Likewise, although the present invention has been described in accordance with use in attaching components inside a computer, it will be appreciated that the locking pin may be useful in any scenario in which a tight locking mechanism is required without the use of tools. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing discussion.  
                                             FIGURE COMPONENT LISTING                                    102   computer housing           104   processor board rack           106   case mounted bracket           108   locking pin           110   rack flange           112   bracket flange           114   locking cam unit           116   sleeve           202   first locked indicator           204   second locked indicator           302   flange circular hole           304   bracket keyed hole           306   anti-rotation protrusion           308   expandable projection           310   keyed hole ends           402   retention groove           404   retention lip           406   cam retaining bulge           408   ellipse shape           410   concave end           412   cam unit disc           414   rotation limiting pin           416   thumb grip           418   castled perimeter           420   limiting channel           422   mating side           424   cam           426   cam opening           428   cam stem           502   cylindrical portion           504   conical portion           506   bullet nose           508   expandable opening           510   base