Patent Publication Number: US-6904655-B1

Title: Helical drive insertion and ejection

Description:
TECHNICAL FIELD 
   The invention relates generally to coupling components and, more specifically, to the coupling of printed circuit boards and other components. 
   BACKGROUND 
   Various electrical devices and computing systems, such as network routers, utilize printed circuit boards or other removable modules. Printed circuit boards generally have one or more connecters that couple with a socket or receptacle. The connectors often include a plurality of discrete elements, such as pins or tabs. Similarly, the socket or receptacle will include a corresponding number of recesses to receive each of the pins or tabs. 
   Properly inserting a printed circuit board into an electrical device can often be a tedious and difficult task. Each individual pin or tab, for example, requires a certain amount of force to properly seat the printed circuit board into the socket. The total force required to seat the printed circuit board or other module includes the cumulative sum of the forces required to seat each individual pin or tab. Thus, as the number of pins or tabs increase, the force required to seat the printed circuit board likewise increases. 
   Furthermore, in order to assure a proper connection and to minimize any chance of damage, force should be evenly applied to the printed circuit board. That is, the uneven application of force along the printed circuit board may cause the circuit board to twist or otherwise deform and become only partially connected. Similarly, the extraction of printed circuit boards or other devices from such systems often requires a relatively large amount of force, typically about 75–80% of the force required for insertion, that must also be evenly applied across the printed circuit board. 
   The uniform application of force to a circuit board becomes more difficult as the amount of overall force required to properly seat the circuit board increases. To assist in the insertion and retraction of circuit boards and other devices, some systems provide various mechanical aids. Conventional mechanical aids include, for example, incorporating one or more levers, or one or more threaded members, such as alignment screws. The threaded members typically attach to the circuit board and align with a threaded connector coupled with the system. 
   The alignment of a threaded member with a threaded connector, however, can itself be tedious and difficult. Many conventional systems make use of multiple screws that must turn in relative synchronicity in order to apply uniform force. Hence, two (or more) tools, such as screwdrivers, must be used simultaneously, or each individual threaded member must be actuated on an alternating basis in relatively small increments. Additionally problems associated with these mechanical aids are the practical limits of the amount of force they can apply, the difficulty in manipulating these aides, the difficulty in aligning the aides, placing relatively large aides in small spaces, and properly shielding the system to prevent electromagnetic interference (EMI). The same mechanical aids are often used for both insertion and extraction and may have the same problems and drawbacks in either case. 
   SUMMARY 
   In general, the invention relates to a device for assisting in the insertion and extraction of printed circuit boards or other components from a device or system such as a network router. The device, referred to herein as a helical drive insertion and extraction device, may include two general components: a mobile component typically coupled with the printed circuit board or other movable component, and a fixed component typically coupled with the system to which the printed circuit board or other component is being inserted. 
   In particular, the mobile component includes a drive shaft having one or more helical groves that have relatively large points of entry to facilitate the automatic alignment of the drive shaft with the fixed component. The fixed component includes one or more pins that engage each of the helical grooves on the drive shaft. A handle mechanism is coupled with the drive shaft and is sized to fit within the available space while providing a high level of comfort and accessibility to an operator. A spring within the mobile component compresses as the pins near the end of the helical grooves and moves the pin into a detent and provides positive tactile feedback to the operator to indicate the completion of the insertion process. 
   In this manner, the helical drive insertion and extraction device delivers tremendous mechanical advantage while facilitating ease of use. The operator can, for example, fully seat the printed circuit board or other component with a single rotation of the handle. This single turn requires a small amount of torque, such as 5 inch/lbs to rotate, but can cause the device to deliver over 100 lbs of linear force in the seating/unseating direction. The amount of linear force developed, the linear distance traveled and the number of rotations of the handle can all be varied and are determined by the inclination angle of the helical grooves as well as the length and diameter of the drive shaft. Thus, low levels of torque deliver high levels of linear force. In addition, limited rotations of the handle accomplish the delivery of such forces. For example, 90°, 180°, 270°, 360° or any other degree of rotation sufficiently delivers the appropriate amount of force. 
   Generally, relatively small circuit boards or components require only a single helical drive insertion and extraction device. For larger circuit boards or components, it may be advantageous to utilize two or more helical drive insertion and extraction devices, usually positioned at opposite ends of the printed circuit board. Because of the structure of the helical grooves, the device self aligns with the pin(s) provided on the fixed component. A single turn of the handle(s) fully seats the component. Where two helical drive insertion and extraction devices are utilized, an operator can easily turn the handles simultaneously by hand so that force is applied evenly across the printed circuit board. 
   In one embodiment, the invention provides a router having a router housing. A system board is coupled with the router housing and includes a slot configured to receive a removable component. A receptacle assembly is coupled with the housing and includes a throughbore and a pin located within the throughbore. A handle is rotatably coupled with the removable component. A drive shaft is coupled with the handle and includes a first helical groove configured to cooperate with the pin. Rotation of the handle causes the drive shaft to rotate and the pin to travel along the helical groove that causes the removable component to move relative to the system board. 
   In another embodiment, a threaded member positioned within the handle of the helical drive insertion and extraction device provides such a locking mechanism that prevents unauthorized access to, or removal of, the printed circuit boards or other components from the system. When a printed circuit board is fully and properly seated, the threaded member in the handle aligns with a threaded connector in the fixed component and engages the threaded connector. In this fashion, an operator must engage the threaded member with a suitable tool to access the printed circuit board. 
   In another embodiment, the drive shaft has a first helical groove entry having a width that is greater than the width of the first helical groove, wherein at least a portion of the first helical groove entry is defined by a first inclined entry guide. 
   In another embodiment the drive shaft has a second helical groove and a second helical groove entry that includes a second groove point. A second inclined entry guide defines a portion of the second helical groove entry. 
   In another embodiment, a first detent forms a terminus of the first helical groove and is configured to receive the pin. 
   In another embodiment, the present invention includes a drive shaft having a proximal end and a distal end with a first helical groove disposed along the distal end, wherein the first helical groove includes a first enlarged entry. A handle is coupled to the proximal end of the drive shaft. A receptacle assembly has a first throughbore and a pin disposed within the through bore wherein the throughbore is configured to receive the distal end of the drive shaft and automatically align the pin with the first helical groove so that rotation of the handle causes rotation of the drive shaft which causes the pin to travel along the first helical groove. Rotation of the drive shaft in a first direction causes the proximal end to move towards the receptacle assembly and rotation in a second direction causes the proximal end to move away from the receptacle assembly. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is an exploded perspective assembly view of an example helical insertion and extraction device. 
       FIG. 2A  is a side elevational view of a drive shaft from the example helical insertion and extraction device. 
       FIG. 2B  is a top elevational view of a drive shaft from the example helical insertion and extraction device. 
       FIG. 2C  is a side elevational view of a drive shaft on another example helical insertion and extraction device. 
       FIG. 3  is a front elevational view of a receptacle assembly of the example helical insertion and extraction device. 
       FIG. 4  is side elevational schematic illustration of an example helical insertion and extraction device coupled with a printed circuit board prior to insertion into a system. 
       FIG. 5  is side elevational schematic illustration of an example helical insertion and extraction device coupled with a printed circuit board prior after insertion into a system. 
       FIG. 6  is a flowchart illustrating the process of using the helical insertion and extraction device. 
   

   DETAILED DESCRIPTION 
     FIG. 1  is an exploded perspective assembly view of a helical insertion and extraction device, referred to as helical device  10 , that assists in the insertion and extraction of printed circuit boards or other components from a device or system such as a network router. In general, helical device  10  includes a moveable component formed by housing  12 , a drive shaft  14  and a handle  16 , as well as a fixed component formed by receptacle assembly  18 . An operator typically interacts with handle  16  to insert or extract a printed circuit board assembly  13  or other components from a system to which receptacle assembly  18  is affixed. 
   In particular, drive shaft  14  passes through shaft hole  20  and includes a proximal end  22  having a flattened portion  24  that engages with handle  16  so that rotation of handle  16  causes rotation of drive shaft  14 . In response to rotation of handle  16 , drive shaft  14  selectively engages receptacle assembly  18 . A first helical groove  26  and a second helical groove  28  are located near a distal end  30  of drive shaft  14 . First groove point  34  partially defines the entry into first helical groove  26 , which terminates in a detent  32 . 
   Proximal end  22  passes through washers  40 A,  40 B and shaft hole  20 . A variety of washers  40 C,  40 D,  40 E,  40 F may be placed on proximal end  22 . Compression spring  36  is placed over proximal end  22  between handle  16  and housing  12 , and allows drive shaft  14  a limited amount of linear movement with respect to housing  12 . A retaining clip  38  secures the various components into place as it is placed onto proximal end  22 . 
   Distal end  30  selectively enters and passes through throughbore  46 . First pin  48 A engages first or second helical groove  26 ,  28 . Thus, assuming receptacle assembly  18  is held stationary, drive shaft  14  must rotate in order for first pin  48 A to follow first or second helical groove  26 ,  28 . 
   Housing  12  may also include one or more mounting holes to receive threaded connectors  44 A,  44 B, thereby fixing housing  12  to assembly  13 . Handle  16  may include one or more threaded members  42 , located and rotatable within a throughbore  43  within handle  42 . Threaded member  42  selectively engages threaded connector  45 , thus securing handle  16  relative to assembly  13 . Threaded member  42  can be positioned so that it only engages threaded connector  45  when handle  16  is properly oriented, thereby assuring proper positioning of handle  16  relative to housing  12  during operation of helical device  10 . 
     FIG. 2A  is a side elevational view of drive shaft  14 , while  FIG. 2B  is a top elevational view of drive shaft  14  rotated 90° from the position illustrated in  FIG. 2A . Helical device  10  gains substantial mechanical advantage during its operation because of the configuration of drive shaft  14 . That is, a relatively small rotational force applied to handle  16  translates into a relatively large amount of linear force between drive shaft  14  and receptacle assembly  18 . First and second helical grooves  26 ,  28  provide this mechanical advantage, which is a function of the angle of inclination of the grooves  26 ,  28 , i.e., the angle at which grooves  26 ,  28  traverse shaft  14 . For example, the mechanical advantage achieved by device  10  increases as the angle of inclination approaches 90° relative to shaft  14 . Similarly, the mechanical advantage decreases as the angle of inclination approaches horizontal, although a greater linear distance of travel is achieved. 
   A single helical groove or more helical grooves could also be utilized. To facilitate the automatic alignment of helical grooves  26 ,  26  with pins  48 A,  48 B ( FIG. 3 ), grooves  26 ,  28  begin as relatively large gaps that terminate in relatively tapered points. For example, first groove point  34  forms a portion of first helical groove  26  and second helical groove  28 . In particular, first groove point  34  forms a small stubbing surface to readily deflect pins  48 A,  48 B into one of the helical grooves  26 ,  28 . 
     FIG. 2B  more clearly illustrates the widened structure of first helical groove entry  50  which transforms into first helical groove  26 . As illustrated, first and second helical groove points  34 ,  56  form the upper and lower (as illustrated) boundaries of entry  50 . Groove points  34 ,  56  taper towards each other along first and second inclined entry guides  52 ,  54  which eventually channel into first helical groove  26 . Thus, first entry  50  automatically guides one of pins  48 A or  48 B ( FIG. 3 ) into first helical groove  26 . Alternatively, a second entry (not separately shown) on the opposite side of drive shaft  14  guide pin  48  into the second helical groove  28 . This occurs either because of random alignment or because groove point  34 ,  56  deflects one of pins  48 A or  48 B. In other words, insertion of drive shaft  14  into receptacle assembly  18  results in the automatic alignment of pins  48  with grooves  26 ,  28  so that rotation can begin immediately. Once within first helical groove entry  50 , rotation of drive shaft  14  causes pin  48  to travel along first helical groove  26 . 
   Eventually, as drive shaft  14  is rotated, pin  48  reaches first detent  32 . As this occurs, housing  12  and handle  42  compress spring  36  ( FIG. 1 ) somewhat. Thus, as pin  48  reaches the end of first helical groove  26 , compression spring  36  expands and forces pin  48  into first detent  32 . This motion produces a tactile sensation that is perceivable by the operator. Rotation of drive shaft  14  in the opposite direction easily overcomes the biasing of compression spring  36 , thus causing pin  48  to leave detent  32  and travel along first helical groove  26 . 
     FIG. 2C  is a side elevational view of another embodiment for drive shaft  14 . In particular, drive shaft  14  may comprise a single groove point  35  forming a larger stubbing surface  55  and a smaller opening  51  for receiving pins  48 A, B. 
     FIG. 3  is a front elevational view of receptacle assembly  18 . Located within throughbore  46  are one or more pins  48 A,  48 B (collectively, pins  48 ). Pins  48  may be provided for helical grooves  26 ,  28  on drive shaft  14 . In this embodiment, two helical grooves and two pins  48  are utilized. Of course, fewer pins  48  than grooves could be provided. Also, pins  48  may be any size or shape for engaging groves  26 ,  28 . Receptacle assembly  18  may be attached to an object, such as an electrical device or computing system, and is referred to herein as the fixed component. Threaded connectors (or any other connecting device) may couple receptacle assembly  18  to the object. Alternatively, receptacle assembly  18  may be formed integrally with the object. 
     FIG. 4  is side elevational schematic illustration of first and second helical devices  10 ,  11  coupled with a printed circuit board (PCB)  60  prior to insertion into a system board  62 . System board  62  may be, for example, mounted within a network router  100  having a router housing  110 . PCB  60  includes some type of connector, schematically illustrated as pins  64  that mate with sockets  66  on system board  62  when an appropriate amount of force is applied to PCB  60 . A pair of plates or tabs  70 A,  70 B extend from PCB  60  for securing the mobile portions of first and second helical devices  10 , 11  respectively. Receptacle assemblies  18 A,  18 B are coupled with a system containing board  62  and sockets  66 . 
   For insertion, PCB  60  is generally aligned as illustrated in  FIG. 4  and moves in a linear direction from left to right (as illustrated). As this occurs, drive shaft  14  facilitates the entry of pin  48 B into first helical groove entry  50 . When positioned such that first or second groove point  34 ,  54  ( FIG. 2B ) align with and abut pin  48 B, the linear motion combined with the inclined plane of entry  50  facilitate proper alignment. In some cases, a minimal rotation of handle  16  may be useful to align entry with the pins, but this is typically not necessary because of the shape of entry  50 . Once entry  50  is positioned as illustrated, further linear movement (from left to right) occurs until pin  48 B abuts a transition portion  72  of first helical groove  26 . Transition portion  72  transforms first inclined entry guide  52  into first helical groove  26 . In the illustrated embodiment, this alignment may be performed substantially simultaneously for first and second helical devices  10 ,  11 . 
   When the operator rotates handle  16  clockwise, drive shaft  14  rotates, causing pin  48 B to follow first helical groove  26 . Simply pushing PCB  60  will also cause pin  48 B to follow first behind groove  26 . Although handle  16  is illustrated as centered on drive shaft  14 , handle  16  could also be offset. This would allow handle  16  to function in environments where space is limited and would allow an operator to clearly determine when handle  16  is properly positioned. As handle  16  rotates, drive shaft  14  (and hence PCB  60 ) moves towards system board  62 . As pin  48 B nears the end of first helical groove  26 , compression spring  36  ( FIG. 1 ) compresses somewhat. When able, compression spring  36  expands which causes pin  48 B to enter detent  32  ( FIG. 2B ). This provides a snap or click that is perceivable by the operator. 
     FIG. 5  is a side elevational schematic view of helical device  10  when an operator has fully inserted PCB  60  into socket  66 . In this position, PCB  60  is snuggly mated with system board  62  and EMI leakage is reduced because no additional areas of system board  62  need be exposed. To remove PCB  60 , an operator reverses the process and turns handle  16  counter clockwise until PCB  60  separates from system board  62 . With either insertion or extraction, it may be desirable to turn handles  16  of both helical devices  10 ,  11  simultaneously. 
   The configuration of helical device  10  offers various advantages. For example, a relatively small amount of torque or rotational force applied to handle  16  delivers a relatively large amount of linear force to insert or extract PCB  60 . In the illustrated embodiment, a single 360° rotation of handle  16  fully seats or unseats PCB  60 . Rotation of handle  16  requires about five inch/lbs of torque to develop over 100 pounds of linear force. Of course, the required amount of rotation of handle  16 , the force required to rotate handle  16  and the linear force developed can all be varied using alternative embodiments. The inclination of helical grooves  26 ,  28  can be varied to make the travel of drive shaft  14  more or less rapid as well as varying the distance of travel achieved. 
   No additional tools are required to insert/extract PCB  60  into system board  62 . That is, helical device  10  provides the operator with all that is required to quickly and easily perform insertion and extraction. However, in some contexts it may be desirable to provide a locking mechanism so that PCB  60  is not accessed by unauthorized personal. To achieve this, handle  16  locks relative to assembly  13 . As explained with reference to  FIG. 1 , locking device  42  is provided in handle  16  and connects with threaded connector  45 . Locking device  42  may simply be a screw or bolt that only requires the use of a screwdriver or similar common tool. In other words, locking device  42  makes it necessary to use some tool to remove PCB  60 , though the actual extraction does not require a tool beyond helical device  10 . Alternatively, locking device  42  could be configured to require a key or other unique access tool, depending upon the level of security desired. 
   Thus, within the space already provided for PCB  60 , helical device  10  offers a fast and easy way to insert/extract PCB  60  quickly and efficiently. High amounts of force can be achieved, no tools are required, alignment is easy and automatic, force is evenly applied, EMI integrity is maintained, and only a small amount of rotation is required. 
     FIG. 6  is a flow chart illustrating the process of connecting a printed circuit board to a system board with helical device  10 . The process starts when an operator aligns a printed circuit board with a corresponding system board ( 102 ). Then, the operator inserts the tip of the each of the drive shafts  14  into receptacle assembly  18  ( 104 ) so that helical grooves  26  and  28  on drive shaft  14  automatically aligns with pin  48  located within receptacle assembly  18 . Next, the operator rotates handle  16  ( 106 ) causing pin  48  to travel along either helical groove  26  or  28  so that the printed circuit board assembly  13  moves towards the system board. After the printed circuit board is connected, the operator then optionally secures handle  16  ( 108 ) so that unauthorized access is hindered and the process is complete ( 110 ). To remove the printed circuit board assembly  13 , the operator reverses the process illustrated in  FIG. 4 . 
   A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims. For example, the number of helical devices utilized with a given printed circuit board may be varied from one to many. The rotation of the handle required to full insert or extract the board can vary from a small fraction of a rotation to one or more full rotations. The number and angles of the helical grooves may be varied. Finally, the present invention may be used on any number of objects that need to be inserted or extracted and are not limited to printed circuit boards.