Abstract:
A lever assembly for use with electronic modules has a handle lever with a self-sprung cantilevered handle section. The cantilevered handle section can be flexed with respect to the non-cantilevered portion of the handle lever during module insertion to automatically engage a catch that prevents the handle lever from inadvertently or accidentally being released and unseating the module. Once the flexing force is removed, compression of the handle section remains at the catch, such that the handle section continues to apply leverage force in the closure direction to hold the module securely in place.

Description:
BACKGROUND 
     1. Field of the Invention 
     The present disclosure relates generally to rack-mounted electronic devices, and more particularly to mechanical connection of electronic modules to a rack-mounted chassis. 
     2. Description of Related Art 
     Large electronic systems typically mount in racks that accept many different kinds of networking and computer gear. Some such systems are themselves often modular—“cards,” “blades,” “modules,” and the like slide into a chassis built to accommodate multiple such units, with the chassis providing power, cooling, and/or intercommunication (e.g., across a backplane) for the modules. Each module is typically provided with one or more screws that align with holes in the chassis, allowing the module to be secured once inserted in the chassis. 
     Some modules, e.g., those that mate a large number of connector pins with a backplane, require significant force to fully make or break the electrical connectors. To this end, some modules provide one or more handles that leverage off of a chassis member to allow a technician to provide the force necessary to make or break the electrical connectors. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be best understood by reading the specification with reference to the following Figures, in which: 
         FIG. 1  illustrates, in exploded perspective view, a circuit module latch injector/ejector according to an embodiment; 
         FIGS. 2A and 2B , show in assembled perspective view, the embodiment of  FIG. 1  unlatched and latched, respectively; 
         FIG. 3  shows a top view of an assembled circuit module latch injector/ejector according to an embodiment; 
         FIGS. 4A-4H  show a circuit module provisioned with a circuit module latch injector/ejector according to an embodiment, during various positions during insertion and extraction of the module from a chassis; and 
         FIG. 5  shows a circuit module latch injector/ejector according to an embodiment with a screw securing mechanism. 
     
    
    
     DETAILED DESCRIPTION 
     Prior art module retention systems and insertion/extraction handles have a variety of disadvantages. The use of make-up screws and the like to retain modules is inconvenient. Accessing the screws during module replacement may be difficult in some systems, due to limited visibility and workspace when neighboring modules remain connected to a large number of cables. Difficulty in starting the screws or damage to chassis threads can occur with slight misalignment. Some users thus tend to shortcut by engaging a module with the backplane using the insertion handles, and then relying on backplane connector friction to hold the module in place instead of making the retention screws up to the chassis. Modules that are not properly retained are subject to inadvertent—and possibly intermittent—disconnection of one or more backplane connections due to vibration, tugging due to the changing of external module connections or persistent cable tension, inadvertent bumping, and the like. Some users may also exert undue force on the insertion handles, not knowing when a reliable connection has been effected, resulting in possibly expensive damage to one or more system components. 
     The described embodiments provide a module insertion/extraction function and a module retention function integrated in a common lever assembly. A handle lever provides leverage for making and breaking module connections, e.g., to a backplane. The handle lever contains a cantilevered section that translates, under force, to a locking position when the module is fully inserted. This cantilevered section remain under spring compression when locked, providing a continuous retention force for the module. A release trigger unlocks the compressed section, allowing the handle lever to swing freely to a position that provides leverage for removing the module. In at least some embodiments, a user can engage and lock a module in a single motion of the handle lever, with no guessing as to when the module is fully engaged, and no separate action or mechanism required to secure the module. 
       FIG. 1  illustrates, in an exploded perspective view, the components of a lever assembly  100  according to a first embodiment. Lever assembly  100  comprises a mounting plate  110 , a handle lever  120 , a latch plate  130 , and a swivel fastener  140 . 
     Mounting plate  110  supports the connection of lever assembly  100  to, e.g., a corner of an electronic module. Vertical (e.g., vertical support  112 ) and horizontal (not visible in this view) members provide stiffness and attachment points for the lever assembly. Horizontal plate  114  contains a mounting hole  116  to receive swivel fastener  140 , a semicircular limit hole  118  that receives a limit tab ( 122 ) on the handle lever  120 , and a latch cutout  119  that allows user access to the latch mechanism, described below. Mounting plate  110  is typically fabricated from sheet aluminum or galvanized steel, machined and formed to produce the shape depicted. 
     Handle lever  120  provides leverage to allow a user to insert and remove a circuit module, and also cooperates with latch plate  130  to provide a module retention function. Handle lever  120  contains a cantilevered handle  125  that swivels about a mounting hole  121  to provide insertion leverage against a leverage face  123 , and extraction leverage against a leverage face  124 . Limit tab  122  projects upward from handle lever  120 , within limit hole  118  when assembly is complete, to provide hard stops at both ends of the handle lever travel range. Handle lever  120  is typically fabricated of stainless spring steel plate or galvanized spring steel plate, machined and bent (tab  122 ) to form the shape depicted. 
     Handle  125  contains a looped opening large enough for an operator to insert several fingers in order to grasp the handle. The looped opening is not, however, a closed shape. Instead, a channel  127  separates the front section of the looped opening from the rear section of the looped opening on the inboard side of the handle lever. In the  FIG. 1  embodiment, the looped opening is approximately oval (resembling on oval racetrack with straightaways oriented parallel to the long axis of handle lever  120 ) in shape, with the channel  127  starting near the backside (the side closest to the equipment when the latch is closed) inboard corner of the oval. The channel angles away from the backside of the handle lever  120  as it diverges from the oval opening, such that by the time the channel approaches the swivel end of handle lever  120 , the back section of the handle lever is wide enough to accommodate mounting hole  121  and limit tab  122 . Channel  127  then curls toward the front face of handle lever  120 , forming a concave opening in the back section of the handle lever. 
     Due to the positioning of channel  127 , substantially the entirety of the oval opening in handle  125  is defined by a cantilevered handle member extending from the backside of the handle lever  120 . The cantilevered handle member comprises handle  125 , lock tab  126 , and force limit tab  129 . The cantilevered construction allows the cantilevered handle member to flex as force is applied to it, with the degree of flexion determined by the cantilevered length, cross-sectional dimensions, and material type selected for handle lever  120 . The amount of flexion due to pushing on handle  125  is limited by force limit tab  129  striking the back side of channel  127 . The amount of flexion due to pulling on handle  125  is limited by force limit tab  129  striking the front side of channel  127  (surface  128 ). Thus movement of handle  125  under force can be maintained within the elastic limits of the material by controlling the resting difference between limit tab  129  and channel  127  (both the backside and surface  128 ). 
     Latch plate  130  comprises a plate having a mounting hole  131  to receive swivel fastener  140  and a spring latch arm  132 . Spring latch arm  132  is a cantilevered section of the plate that extends away from the module served by lever assembly  100 , the latch arm terminating in a release tab  133  projected above the remainder of latch plate  130  by an intermediate vertical catch surface  134 . Latch plate  130  is typically fabricated from sheet spring steel or spring stainless steel, machined and formed to produce the shape depicted. 
     Swivel fastener  140  comprised a rivet or other common fastener that can pass through mounting holes  116 ,  121 , and  131  to hold mounting plate  110 , handle lever  120 , and latch plate  130  together while allowing rotation of handle lever  120  with respect to plates  110  and  130 . 
       FIGS. 2A and 2B  illustrate an assembled view of lever assembly  100 , respectively, in closed, unlatched and closed, latched positions  200  and  201 . In  FIG. 2A , handle lever  120  is fully closed, either because limit tab  122  is resting against the close limit surface  119  of mounting plate  110 , or because the module to which the lever assembly is attached (not shown) has reached its mechanical insertion limit. In this position, lock tab  126  depresses release tab  133  such that handle  125  rides over the top of release tab  133 . 
     In  FIG. 2B , a force F is applied to handle  125 , once further movement of handle  125  is resisted by limit tab  122  or a module&#39;s mechanical insertion limit. Force F causes handle  125  to flex such that lock tab  126  clears the vertical catch surface  134 , allowing release tab  133  to spring up to its normal position. When force F is relaxed, spring force attempts to restore lock tab  126  to its relaxed position. Vertical catch surface  134  now acts as a complementary feature to engage lock tab  126 , interfering with the backwards movement of lock tab  126 , such that handle lever  120  remains in a latched position. The compression of handle  125  with the vertical catch surface engaged exerts a force on leverage face  123  to maintain a module snugged in place. 
     To remove the module, an operator presses down on the top surface of release tab  133  until vertical catch surface  134  clears the front face of lock tab  126 , allowing lock tab  126  to spring back to its relaxed position. Handle lever  120  now is in the  FIG. 2A  position, and is free to swing forward to extract the module. 
       FIG. 3  illustrates a top view  300  of the assembly. Additional mounting structure, including a lateral mounting tab  301  with mounting holes  302  not visible in  FIGS. 1 ,  2 A, and  2 B, and an alignment prong  303 , are visible in top view  300 . Alignment prong  303  inserts in a matching slot in a module (not shown), and then the rear surface  304  of mounting plate  110  (as well as the rear surface of mounting plate  130  underneath) are made up against the front of the module and secured by screws (not shown) through holes  302 . 
       FIGS. 4A-4H  show, from a top view, the insertion and extraction of a module  400 , equipped with an exemplary lever assembly embodiment, from a chassis  410 . Module  400  comprises a connector block  402 . Chassis  410  comprises a complementary connector block  412 . The side of chassis  410  includes a mounting extension  414  with a latching notch  416 . An EMI (ElectroMagnetic Interference) gasket  404  is also shown affixed to module  400 —gasket  404  slides along the inner surface of mounting extension  414  as module  400  is inserted in chassis  410 . 
     In  FIG. 4A , module  400  is loosely engaged with chassis  410 . Handle lever  120  is free to move in a range of extended to semi-extended positions. 
     In  FIG. 4B , module  400  has been slid into chassis  410  to a point where connector blocks  402  and  412  almost begin to engage. Leverage face  124  of handle lever  120  contacts the front of mounting extension  414 , such that handle lever  120  begins to close. 
     Referring now to  FIG. 4C , handle lever  120  is now swung back toward the module face until leverage face  123  of handle lever  120  enters latching notch  416  and comes to rest against the front end of the latching notch. 
     In  FIG. 4D , handle lever  120  is pushed back toward the module face, which causes leverage face  123  to push against the front end of latching notch  416  on mounting extension  414 . This causes module  400  to slide back fully into chassis  410 , making connector blocks  402  and  412 . When the module is fully engaged, further force on handle lever  120  causes latch tab  126  to flex toward the face of the module, freeing release tab  133  from underneath latch tab  126 . Release tab  133  springs upward to its relaxed position, latching handle lever  120  in the flexed position. Handle lever  120  holds module  400  secure as long as the handle lever remains latched. 
       FIGS. 4E-4H  illustrates a process for unlatching and removing module  400  from chassis  410 . In  FIG. 4E , release tab  133  is depressed such that the vertical face  134  of the release tab drops below latch tab  126 . This causes latch tab  126  to spring forward to its relaxed position, once again trapping release tab  133  below the handle lever  120 . Handle lever  120  is now in an unlatched position. 
     Once handle lever  120  is unlatched, it may now be pulled forward to the position shown in  FIG. 4F , where leverage face  124  contacts the front of mounting extension  414 . Then, as handle lever  120  is pulled further forward, leverage face  124  pushes against mounting extension  414 , pulling module  400  forward and decoupling connector blocks  402  and  412  ( FIG. 4G ).  FIG. 4H  shows handle lever  120  at full extension. From anywhere between the  FIG. 4G  and  FIG. 4H  positions, module  400  should slide easily from chassis  410 . 
     Various other embodiments can utilize the concepts described to provide a latching handle.  FIG. 5  shows a lever assembly  500  having a latching function and a lock function, lever assembly  500  including a mounting plate  510 , a latch handle  520 , a backing plate  530 , and a swivel fastener  540  that holds latch handle  520  between plates  510  and  530 , while allowing relative rotation of latch handle  520 . 
     Mounting plate  510  is similar in many respects to mounting plate  110  of the first embodiment. A semicircular limit hole  518  receives a limit tab  522  on a handle lever  520 , for instance. Three new features are shown as well on mounting plate  510 . A latch hole  511  and a latch guide channel  512  are arranged in a second semicircular arc outboard of semicircular limit hole  518 , and a locking fastener receiver  513  projects above the plane of the mounting plate  510 . The function of each are described below with reference to the complementary features of latch handle  520 . 
     Latch handle  520  includes a limit tab  522  and a cantilevered handle section  525  including a catch tab  523 , a release tab  526 , and a locking fastener retainer  524  that captures a locking fastener  550 . Limit tab  522  swings within semicircular limit hole  518  between a fully open stop at one end of the limit hole and a fully closed stop at the other end of the limit hole. Catch tab  523  swings within latch guide channel  512  until the latch handle nears the closed position. As the latch handle nears the closed position and meets resistance, either because a module is nearing full insertion or because limit tab  522  meets its closed stop, further force on the cantilevered handle section  525  flexes section  525  with respect to the non-cantilevered portion of latch handle  520 . As the cantilevered handle section  525  flexes, catch tab  523  rides under the end of latch guide channel  512  until catch tab  523  pops into latch hole  511 . Catch tab  523  and latch hole  511  then engage to prevent cantilevered handle section  525  from springing fully back to its relaxed position. 
     When catch tab  523  and latch hole  511  are engaged, locking fastener  550  is brought into alignment with locking fastener receiver  513 . An operator desiring to prevent easy opening of the latch handle engages locking fastener  550  with locking fastener receiver  513 . For instance, locking fastener  550  can be a spring-loaded screw with a threaded section or a key that engages with complementary features in locking fastener receiver  513  when the screw is depressed and turned. To unlock the fastener, the screw is depressed and turned in the opposite direction to free it from locking fastener receiver  513 . 
     To disengage catch tab  523  from latch hole  511 , an operator presses down on release tab  526  to flex cantilevered handle section  525  orthogonal to the direction of closure and opening. Movement of cantilevered handle section  525  in this direction is resisted, and ultimately stopped, by backing plate  530 . Backing plate  530  flexes within elastic limits sufficient to move catch tab  523  below the plane of latch hole  511 , at which time the compression on cantilevered handle section  525  is released, springing catch tab  523  back into latch guide channel  512 . Handle lever  520  is now free to rotate to its open position as desired. 
     Those skilled in the art will appreciate that the embodiments and/or various features of the embodiments can be combined in other ways than those described. Although small electronic modules using one latch handle are shown in the operational figures, larger modules may advantageously apply two latch handles, one on each side, or in other desirable arrangements. The latch handle may also be mounted to the chassis instead of the modules if so desired. A locking function, such as that shown on the  FIG. 5  embodiment, may also be included on the  FIG. 1  embodiment. Numerous complementary feature arrangements are compatible with the disclosed lever assemblies and method of holding a cantilevered handle section under compression. Likewise, numerous locking fastener arrangements are also possible. Many other examples of optimizations or implementation differences exist within the broad scope of this disclosure. 
     Although the specification may refer to “an”, “one”, “another”, or “some” embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment.