Abstract:
Disclosed is a cable chain return system  100  that includes a spring  170  for assisting folding and organization of a cable chain  110 . When a customer replaceable unit (CRU)  210  is extended from a chassis  140  to gain access to connectors on the back of the CRU  210 , the cable chain  110  is extended. When the CRU  210  is moved back into the chassis  140 , a plurality of folding curves  130  organize the cable chain  110 , and cables  118  therein, without damaging the cables  118  or inhibiting positioning of the CRU  210  in the chassis  140 . One of these curves  130  is initiated by the spring  170  and therefore aids in returning and organizing of the cable chain  110.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a continuation-in-part of U.S. Non-Provisional patent application Ser. No. 12/208,182 entitled “ARTICULATING CABLE CHAIN ASSEMBLY”, and filed Sep. 10, 2008 by ALAN T. PFEIFER. The aforementioned application is assigned to an entity common hereto, and the entirety of the aforementioned application is incorporated herein by reference for all that it discloses and teaches. 
     BACKGROUND OF THE INVENTION 
     Customer replaceable units (CRUs) have provided a convenient and simple way of replacing appliances such as disk drives in servers, RAID devices, etc. Drives, such as hot spares, mirror drives in a RAID unit, or any type of replacement drive can be easily removed or replaced using CRU devices. Disk drives can be plugged and unplugged from the chassis of RAID units, servers, computers, etc. with cables having connectors that connect to the back of the unit. Hence, the CRUs are a practical and convenient way to replace appliances, such as disk drives, that are utilized in the computer and electronics industry. 
     SUMMARY OF THE INVENTION 
     An embodiment of the present cable chain return system may include a method of returning a cable chain from an extended position to a retained position, the method comprising: providing a cable chain made from a plurality of links having a limited arc of rotation, the links periodically reversed on the articulated cable chain so that the cable chain forms a plurality of folding curves in sequentially opposite directions along the cable chain when the cable chain is in a retained position, the cable chain defining: a proximal end attached to the chassis, a distal end oppositely disposed from the proximal end and attached to a customer replaceable unit; a biased section adjoining the proximal end; and, placing a spring adjacent to the cable chain proximal end that engages the cable chain biased section and the chassis so that the spring biases the cable chain biased section towards the chassis to initiate forming of the plurality of folding curves when the customer replaceable unit is moved from the extended position to the retained position. 
     An embodiment of the present cable chain return system may include a cable chain return system connected to a customer replaceable unit and a chassis, the cable chain return system comprising: a cable chain made from a plurality of links that have a limited arc of rotation, the links periodically reversed on the cable chain so that the cable chain forms a plurality of folding curves in sequentially opposite directions along the cable chain when the a cable chain is in a retained position, the cable chain defining: a proximal end attached to the chassis, a distal end oppositely disposed from the proximal end and attached to the customer replaceable unit, a biased section adjoining the proximal end; and, a spring attached to the chassis adjacent to the cable chain proximal end adjoining the cable chain biased section, the spring disposed on the chassis to bias the cable chain biased section towards the chassis for initiating the plurality of folding curves when the cable chain moves from an extended position to the retained position. 
     An embodiment of the present cable chain return system may include a method of installing a cable chain return system for a customer replaceable unit in a chassis that extends from the chassis, the method comprising: providing a cable chain made from a plurality of links that have a limited arc of rotation, the links periodically reversed on the articulated cable chain so that the cable chain forms a plurality of folding curves in sequentially opposite directions along the cable chain when the cable chain is in a retained position, the cable chain defining a proximal end and an oppositely disposed distal end; providing a spring comprising: a first coil section and a second coil section integrally formed with the first coil section separated by a spring separation distance from the first coil section; squeezing the spring first and second coil sections causing the spring separation distance to decrease; positioning the spring adjacent to the chassis, after the squeezing the spring; releasing the spring, after the positioning the spring; positioning the cable chain proximal end between the first coil section and the second coil section, after the releasing the spring; and, attaching the cable chain to the chassis between the spring first and second coil sections thereby installing the cable chain return. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  is a perspective view of an embodiment of a cable chain return system that is in a retained position. 
         FIG. 1   b  is a top plan view of the embodiment of the cable chain return system of  FIG. 1   a.    
         FIG. 2  is a perspective view of the cable chain return system of  FIG. 1   a  in an extended position having a CRU that can be released from the cable chain. 
         FIG. 3  is a top plan view of the embodiment of  FIG. 1   a  showing a spring interfaced with the chassis. 
         FIG. 4  is a perspective view of the embodiment of  FIG. 3  detailing a second protrusion formed in the chassis for engaging the spring. 
         FIG. 5  is a perspective view of the embodiment of the spring of  FIG. 1   a.    
         FIG. 6  is a top plan view of the embodiment of the spring of  FIG. 5 . 
         FIG. 7  is a perspective view of the cable chain being installed by a technician after the spring has been interfaced with the chassis as illustrated in  FIG. 3 . 
         FIG. 8  is a perspective view of the cable chain return system of  FIG. 7  after the cable chain has been installed and the spring biases a cable chain biased section adjacent to the chassis. 
         FIG. 9  is a perspective view of another embodiment of a spring interfaced with a chassis. 
         FIG. 10  is a top plan view of the embodiment of the chassis and the interfaced spring of  FIG. 9 . 
         FIG. 11  is a cross-sectional view of the embodiment of the chassis and the interfaced spring taken across plane  11 - 11  of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIGS. 1-8 , in general, illustrate an embodiment of a cable chain return system  100  provided with a cable chain  110 , a chassis  140 , a spring  170  and a customer replaceable unit (CRU)  210 . The cable chain  110  is connected between the chassis  140  and the CRU  210 . The cable chain  110  protects and carries cables  118  that provide electrical communication between electrical components (not shown) of the chassis  140  and the CRU  210 . The cable chain  110  assist in folding the cables  118  in a series of sequentially opposite curves in a “S” formation, so that the cables  118  do not become entangled during movement. The present cable chain return system  100  utilizes the spring  170  for returning the cable chain  110  after it has been extended (as illustrated in  FIG. 2 ) during replacement of the CRU  210  as described later herein. 
       FIG. 1   a  is a perspective view of one exemplary embodiment of the cable chain system  100  in a retained condition. The system  100  is provided with the cable chain  110  defining a proximal end  112  and an oppositely disposed distal end  114 . Cable chain  110  is further provided with a biased section  115  ( FIG. 2 ) adjacent to the proximal end  112 . The biased section  115  extends for a short distance of the cable chain  110 , e.g. four links of the cable chain  110 . Disposed between the proximal end  112  and distal end  114  is an interior conduit  116  for receiving the cables  118 . The cable chain  110  includes a plurality of links, e.g. individual links  120 ,  122 ,  124 , creating an assemblage that defines range of motion and provides the flexible interior conduit  116  for cables  118 . The cables  118  are disposed in the cable chain interior conduit  116  and flex with the cable chain  110  as illustrated in the figures. 
       FIG. 1   b  is a top plan view of the cable chain return system  100  in the retained condition of  FIG. 1   a . The cable chain  110  is folded to form a series of interlinking folds in the cable chain  110  that curve in opposite directions sequentially along the length of the cable chain  110 . The individual links  120 ,  122 ,  124 , etc. ( FIG. 1   a ) that form the cable chain  110  have a limited arc of rotation so that the cable links rotate in only one direction. The links of the cable chain  110  are assembled to create a plurality of folding curves  130 , e.g. first folding curve  132 , second folding curve  134 , and third folding curve  136  as desired. Some of the folding curves  130  are sequentially reversed, for example second folding curve  134  reversed from third folding curve  136 . When the folding curves  130  are sequentially reversed they can curve in sequentially opposite directions along the length of the cable chain  110 . It is desirable to ensure that the folding curves  130  are tightly formed in the retained condition, and that the folding curves  130  are properly initiated when the CRU  210  is in an extended position in the chassis  140  and begins to move to the retained position. If the folding curves  130  in the cable chain  110  are not properly initiated, the cable chain  110  may not properly initiate a folding action, which may prevent the CRU  210  from being stored in the chassis  140  in the manner illustrated in  FIGS. 1   a  and  1   b . The spring  170  improves proper folding of the first folding curve  132  and initiates the other folding curves  134 ,  136 . 
       FIG. 2  shows the cable chain return system  100  in an extended condition. Cable chain  110  is extended such that the proximal end  112  is located from the distal end  114  by a separation distance  113 . The separation distance  113  changes as the cable chain return system  100  is utilized. In the retained condition, the CRU  210  is engaged to and supported by the chassis  140  and the separation distance  113  is relatively short, as illustrated in  FIG. 1   b . In the extended condition, the CRU  210  is able to be disengaged and is not supported by the chassis  140  and the separation distance  113  is relatively long. In this extended condition, the cable chain return system  100  has return energy stored in the spring  170 . The return energy in the spring  170  is utilized for folding and organizing the cable chain  110  as it moves to a retained position required for the retained condition. Specifically, the return energy in the spring  170  biases the biased section  115  ( FIG. 2 ) of the cable chain  110  towards the chassis  140 . In biasing the cable chain  110  towards the chassis  140 , the first folding curve  132  is formed as best illustrated in  FIG. 1   b . The particular operation of the spring  170  is detailed below. 
       FIG. 3  illustrates one exemplary embodiment of the chassis  140 . Chassis  140  may be configured with a c-channel section having a web  142 , a first leg  144  and a second leg  146 . The first and second legs  144 ,  146  may be individual components, or as illustrated in  FIG. 4 , integrally formed with the web  142  and made out of sheet metal. The chassis  140  may be configured with a variety of attachment points such as, for example, a pair of chain holes  148 , a first protrusion  150  and a second protrusion  152 . 
       FIG. 4  shows a perspective view of the chassis  140  of  FIG. 3 . The second protrusion  152  may be formed in an L-shape having a base  154  and an integrally formed leg  156 . If integrally formed out of the chassis web  142 , the second protrusion base  154  is perpendicular and attached to the web  142 . The second protrusion leg  156  is integrally formed with the base  154  creating a feature that can capture the spring  170  as described below. The first protrusion  150  is essentially a mirror copy of the second protrusion  152  and components thereof, e.g. base  154  and leg  156 . 
       FIG. 5  shows a perspective view of one exemplary embodiment of the spring  170 . The spring  170  is made of any of a variety of spring materials, e.g. steel, and provided with a first coil section  172  defining a first end  174  and a second end  176 , a first lever arm  178  and a first reaction arm  180 . The first lever arm  178  protrudes from the first coil section first end  174  and the first reaction arm  180  protrudes from the first coil section second end  176 . The spring  170  may be provided with an interface arm  182  integrally formed on the end of the first lever arm  178  opposite of the first coil section  172 . The spring  170  provided with a second coil section  192  defining a first end  194  and a second end  196 , a second lever arm  198  and a second reaction arm  200 . The second lever arm  198  protrudes from the second coil section first end  194  and the second reaction arm  200  protrudes from the second coil section second end  196 . If the interface arm  182  is present, the interface arm  182  is integrally attached to the second lever arm  198  at a location opposite from the first lever arm  178 . 
       FIG. 6  shows a top plan view of the spring  170  having the first coil section  172  is separated from the second coil section  192  by a spring separation distance  171 . The configuration of the spring  170  allows for a force  173  and an equal but opposite force  193  to be applied to the coil sections  172 ,  192  causing this spring separation distance  171  to decrease. Once the forces  173 ,  193  are released, the spring separation distance  171  increases to its natural length but stopping short of its full spring separation distance  171  if it contacts any immovable components as described below. 
     With reference again to  FIG. 1   a , the cable chain return system  100  is provided with the customer replaceable unit (CRU)  210  such as, for example, a disk drive. This CRU  210  is able to translate relative to the chassis  140  in a first direction  211  and can be detached from the chassis  140  altogether. Detaching of the CRU  210  is useful when the customer needs to replace the CRU  210 . The present cable chain return system  100  improves this replacement by providing access to the cable chain distal end  114  and electrical connectors located at the distal end  114 . The cable chain  110 , chassis  140 , spring  170  and CRU  210  are assembled in sequential steps of: 1) installation of the spring  170  onto the chassis  140 ; 2) installation of the cable chain  110  onto the chassis  140 , thereby securing the spring  170 ; and, 3) installation of the CRU  210 . The above sequential list is provided for illustrative purposes only and is one example of an embodiment that allows for easy installation. It is noted that other assembly processes may be utilized in alternative embodiments presented herein or practiced. 
     Referring again to  FIG. 3 , the spring  170  is installed by a technician applying the first and second forces  173 ,  193  to the first and second coil sections  172 ,  192 , respectively. As the spring separation distance  171  ( FIG. 6 ) decreases it becomes possible to slide the coil sections  152 ,  172  under the legs (e.g. second protrusion leg  156 ,  FIG. 4 ) of the first and second protrusions  150 ,  152 , respectively. Upon locating the spring  170  as illustrated in  FIG. 3 , the technician can release the forces  173 ,  193  to cause the first and second coil sections  152 ,  172  to come into contact with the first and second protrusions  150 ,  152 , respectively. In this orientation, the first and second reactions arms  180 ,  200  contact the chassis web  142  and the reaction arms  178 ,  198  are free to be pivoted about the coil sections  152 ,  172 , as illustrated in  FIG. 7 . 
       FIG. 7  shows the spring  170  being manipulated by a technician (not shown). Following installation of the spring  170  described above, the cable chain  110  can be installed onto the chassis  140 . This process is aided by the pair of chain holes  148  ( FIG. 3 ) formed in the chassis web  142 . As the spring  170  is manipulated by the technician, the cable chain proximal end  112  may be attached to the chassis  140  via the chain holes  148  ( FIG. 3 ) and screws (not shown) located therein. 
       FIG. 8  shows a perspective view of the chassis  140  after the cable chain  110  is attached. The technician has released the spring  170  thereby causing the cable chain  110  to be biased against the chassis  140 . 
     Referring again to  FIG. 2 , the process of installing the cable chain return system  100  is completed by attaching the CRU  210  to the distal end  114  of the cable chain  110 . There are a variety of methods known in the industry for making electrical connections; the most common is manually attaching a connector (not shown) of the cables  118  to the CRU  210 . This manual attachment of the cables  118  to the CRU  210  is possible due to the length of the cable chain  110  and the nature of the cable chain  110  itself (i.e. it can be consolidated,  FIGS. 1   a  and  1   b , or extended,  FIG. 2 ). 
     Referring again to  FIG. 1   a , the foregoing description of initial installation of the CRU  210  is reversed and repeated by a user to aid in maintenance and/or repair of CRUs (e.g. CRU  210 ). The user can gain access to and impart a force on the CRU  210  causing it to move in the first direction  211  into an extended condition as illustrated in  FIG. 2 . The user can remove the CRU  210  by manually detaching the cables  118  ( FIG. 1   a ) and replace the CRU  210  with a replacement CRU substantial like CRU  210 . After this replacement, the user reverses the force on the CRU  210  causing the CRU  210  to move in a direction opposite from the first direction  211 . Utilizing the return energy stored in the spring  170 , the spring  170  urges the cable chain  110  towards the chassis  140  so that the process of folding the cable chain  110  when the CRU  210  is pushed into the retained position can be completed. The present cable chain return system aids in properly organizing the cable chain  110  during initial installation or replacement of the CRU  210 . 
     Various alternative embodiments have been contemplated by the inventors, for example, the chassis  140  may be configured as a component of a larger assembly as illustrated in  FIGS. 9-11 .  FIG. 9  is a perspective view of this embodiment of the chassis and a spring interfaced.  FIG. 10  is a top plan view of the embodiment of the chassis and the interfaced spring of  FIG. 9 .  FIG. 11  is a cross-sectional view of the embodiment of the chassis and the interfaced spring taken across plane  11 - 11  of  FIG. 10 . 
     The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variation may be possible in light of the above teachings. The embodiment was chosen and descried in order to best explain the principles of the invention and its practical applications to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.