Abstract:
A latch assembly for a cooling unit of a telecommunications shelf assembly, the latch assembly including: a faceplate; a latch handle movably coupled to the faceplate, wherein, when the latch handle is actuated, the cooling unit is attached to/released from the shelf assembly; and a locking mechanism coupled to the latch handle, wherein, when the locking mechanism is actuated, the cooling unit is locked to/unlocked from the shelf assembly; wherein the locking mechanism includes a fan brake actuator mechanism that is coupled to an electronic fan brake switch associated with one or more fans of the cooling unit. Optionally, the latch handle is pivotably coupled to the faceplate and is actuated by rotation. Optionally, the locking mechanism includes a captive screw that is advanced into/backed out of a threaded aperture associated with the faceplate. Optionally, the fan brake actuator mechanism includes a lever member that couples the locking mechanism to the electronic fan brake switch.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to telecommunications systems and methods. More specifically, the present invention relates to a latch assembly incorporating a fan brake actuator for use in a cooling unit of a telecommunications system. 
       BACKGROUND OF THE INVENTION 
       [0002]    Conventional cooling units of telecommunications systems incorporate an electronic fan brake that stops the spinning fans when the power to the cooling unit is interrupted, such as when the cooling unit is removed from the associated shelf assembly. The intent is to prevent an operator that is removing the cooling unit from the shelf assembly and/or the fan from the cooling unit from being exposed to spinning fan blades, which spin at a relatively high velocity for newer telecommunications systems. As cooling requirements increase, the fans run at higher and higher speeds and take longer and longer to stop once the electronic fan brake is engaged. These fans can take 2 seconds or more to stop—longer than it takes to remove the cooling unit from the shelf assembly. This puts fingers and the like in danger. 
         [0003]    Newer telecommunications systems utilize relatively large cooling units that are secured via a latch mechanism that is rotatably engaged and disengaged. The natural tendency of an operator when removing such a cooling unit is to place one hand on the latch handle and pull, thereby rotating the latch mechanism, using the other hand to take the weight of the cooling unit from underneath. This can result in a hazardous condition if the exposed fans are still spinning. As stated herein above, most conventional fans have a spin down time of several seconds, and are still spinning when the cooling unit is removed from the shelf assembly. 
         [0004]    It should be noted that, in telecommunications systems that do not utilize an electronic fan brake, it is common to cover the fans with grates that have openings that are too small to admit a finger. Disadvantageously, these grates reduce the cooling performance of the fans and increase acoustic noise. 
         [0005]    Thus, what is still needed in the art is an improved cooling unit that utilizes a latch assembly that triggers the electronic fan brake earlier, such that the fans are not still spinning when a cooling unit is removed from a shelf assembly. The present invention provides such an improved cooling unit, thereby minimizing the risk of operator injury. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    In a variety of exemplary embodiments, the present invention provides an improved cooling unit that utilizes a latch assembly that triggers the electronic fan brake earlier, providing the fans with several seconds to stop when the cooling unit is removed from the shelf assembly, thereby minimizing the risk of operator injury. In fact, the improved cooling unit of the present invention includes fans that are stopped well in advance of the removal of the cooling unit from the shelf assembly. This is accomplished via the use of a captive screw or the like on the latch assembly that is coupled to the switch of the electronic fan brake and acts as a fan brake actuator. This captive screw takes several seconds to disengage, thereby providing the spinning fans with several seconds to stop once the fan brake actuator is actuated. 
         [0007]    In one exemplary embodiment, the present invention provides a latch assembly for a cooling unit of a telecommunications shelf assembly, the latch assembly including: a faceplate; a latch handle movably coupled to the faceplate, wherein, when the latch handle is actuated, the cooling unit is attached to/released from the shelf assembly; and a locking mechanism coupled to the latch handle, wherein, when the locking mechanism is actuated, the cooling unit is locked to/unlocked from the shelf assembly; wherein the locking mechanism includes a fan brake actuator mechanism that is coupled to an electronic fan brake switch associated with one or more fans of the cooling unit. Optionally, the latch handle is pivotably coupled to the faceplate and is actuated by rotation. Optionally, the locking mechanism includes a captive screw that is advanced into/backed out of a threaded aperture associated with the faceplate. Optionally, the fan brake actuator mechanism includes a lever member that couples the locking mechanism to the electronic fan brake switch. A first end of the lever member is coupled to the faceplate, a second end of the lever member contacts the electronic fan brake switch, and the locking mechanism contacts the lever member between the first end and the second end of the lever member. Optionally, the lever member comprises a light pipe that transmits light from an interior portion of the cooling unit to an exterior portion of the cooling unit. 
         [0008]    In another exemplary embodiment, the present invention provides a cooling unit of a telecommunications shelf assembly, the cooling unit including: a faceplate; and a latch assembly, including: a latch handle movably coupled to the faceplate, wherein, when the latch handle is actuated, the cooling unit is attached to/released from the shelf assembly; and a locking mechanism coupled to the latch handle, wherein, when the locking mechanism is actuated, the cooling unit is locked to/unlocked from the shelf assembly; wherein the locking mechanism includes a fan brake actuator mechanism that is coupled to an electronic fan brake switch associated with one or more fans of the cooling unit. Optionally, the latch handle is pivotably coupled to the faceplate and is actuated by rotation. Optionally, the locking mechanism includes a captive screw that is advanced into/backed out of a threaded aperture associated with the faceplate. Optionally, the fan brake actuator mechanism includes a lever member that couples the locking mechanism to the electronic fan brake switch. A first end of the lever member is coupled to the faceplate, a second end of the lever member contacts the electronic fan brake switch, and the locking mechanism contacts the lever member between the first end and the second end of the lever member. Optionally, the lever member comprises a light pipe that transmits light from an interior portion of the cooling unit to an exterior portion of the cooling unit. 
         [0009]    In a further exemplary embodiment, the present invention provides a method for providing and using a latch assembly for a cooling unit of a telecommunications shelf assembly, method comprising: providing a faceplate; providing a latch handle movably coupled to the faceplate, wherein, when the latch handle is actuated, the cooling unit is attached to/released from the shelf assembly; providing a locking mechanism coupled to the latch handle, wherein, when the locking mechanism is actuated, the cooling unit is locked to/unlocked from the shelf assembly; wherein the locking mechanism includes a fan brake actuator mechanism that is coupled to an electronic fan brake switch associated with one or more fans of the cooling unit; actuating the locking mechanism to actuate the electronic fan brake switch; and actuating the latch handle to attach the cooling unit to/release the cooling unit from the telecommunications shelf assembly. Optionally, the latch handle is pivotably coupled to the faceplate and is actuated by rotation. Optionally, the locking mechanism includes a captive screw that is advanced into/backed out of a threaded aperture associated with the faceplate. Optionally, the fan brake actuator mechanism includes a lever member that couples the locking mechanism to the electronic fan brake switch. A first end of the lever member is coupled to the faceplate, a second end of the lever member contacts the electronic fan brake switch, and the locking mechanism contacts the lever member between the first end and the second end of the lever member. Optionally, the lever member comprises a light pipe that transmits light from an interior portion of the cooling unit to an exterior portion of the cooling unit. 
         [0010]    In a still further exemplary embodiment, the present invention provides a shelf assembly for a telecommunications system incorporating a cooling unit and a latch assembly as described herein above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present invention is illustrated and described herein with reference to the various drawings, in which like reference numbers are used to denote like assembly components/method steps, as appropriate, and in which: 
           [0012]      FIG. 1  is a series of perspective views of one exemplary embodiment of the cooling unit of the present invention; 
           [0013]      FIG. 2  is a series of side planar views of one exemplary embodiment of the latch assembly of the present invention, in open (fan disabled) and closed (fan enabled) configurations; 
           [0014]      FIG. 3  is a series of partial perspective views of one exemplary embodiment of the latch assembly of the present invention, in open (fan disabled) and closed (fan enabled) configurations, highlighting the operation of the latch handle and lever member; 
           [0015]      FIG. 4  is a series of perspective views of one exemplary embodiment of the lever member of the present invention; 
           [0016]      FIG. 5  is a perspective view of one exemplary embodiment of a printed circuit board (PCB) of the present invention including electronic fan brake switches and a light emitting diode (LED); 
           [0017]      FIG. 6  is a series of cross-sectional side views of one exemplary embodiment of the latch assembly of the present invention, in open (fan disabled) and closed (fan enabled) configurations; and 
           [0018]      FIG. 7  is a series of top planar views of one exemplary embodiment of the latch assembly of the present invention, in open (fan disabled) and closed (fan enabled) configurations. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Referring now specifically to  FIG. 1 , in one exemplary embodiment, the present invention provides an improved cooling unit  10  that utilizes a latch assembly  12  that triggers the electronic fan brake (not illustrated) earlier, providing the fans  14  with several seconds to stop when the cooling unit  10  is removed from the shelf assembly (not illustrated), thereby minimizing the risk of operator injury. In fact, the improved cooling unit  10  of the present invention includes fans  14  that are stopped well in advance of the removal of the cooling unit  10  from the shelf assembly. This is accomplished via the use of a captive screw  16  or the like on the latch assembly  12  that is coupled to the switch (not illustrated) of the electronic fan brake and acts as a fan brake actuator. This captive screw  16  takes several seconds to disengage, thereby providing the spinning fans  14  with several seconds to stop once the fan brake actuator is actuated. As may be seen, the cooling unit includes a housing  18  that defines a plurality of ports  20  in and through which the fans  14  are disposed, such that they may establish a cooling air flow from the interior of a shelf assembly to the external environment, thereby drawing heat off of the shelf assembly. The housing  18  includes a faceplate  22  that typically faces the front portion of the shelf assembly and is accessible by an operator. The housing  18  also includes suitable backplane connections  24  and the like for drawing power from the shelf assembly. In the exemplary embodiment illustrated, four fans  14  utilizing a single electronic fan brake are utilized, although it will be readily apparent to those of ordinary skill in the art that more or fewer fans could be utilized, multiple electronic fan brakes could be utilized, etc. In general, the housing  18  is slid into a corresponding opening in the front of the shelf assembly, secured via actuation of the latch assembly  16 , and locked to the shelf assembly via actuation of the captive screw  16 . This enables the fans  14 . The opposite procedure disables the fans  14  and allows the cooling unit  10  to be removed from the shelf assembly. 
         [0020]    Referring now specifically to  FIG. 2 , in one exemplary embodiment, the latch assembly  12  includes a handle portion  26  to which the captive screw  16  is attached and through which the captive screw  16  protrudes. The latch assembly  12  also includes a pawl portion  28  that is configured to engage a corresponding recess or protrusion (not illustrated) manufactured into or coupled to the shelf assembly. The latch assembly in pivotably coupled to the faceplate  22 , such that actuation of the handle portion  26  rotates the pawl portion  28  with respect to the faceplate  22 , thereby catching or releasing the recess or protrusion of the shelf assembly and biasing the housing  18  ( FIG. 1 ) into or releasing the housing  18  from the shelf assembly. A pivot pin  30  is provided for this purpose. It will be readily apparent to those of ordinary skill in the art that other comparable mechanisms may be used to bias the housing  18  into or release the housing  18  from the shelf assembly, and may work with the locking mechanism (i.e. captive screw  16 ) of the present invention. 
         [0021]    The captive screw  16 , which is rotatably disposed through the handle portion  26  of the latch assembly  12 , selectively engages a threaded port  32  that is coupled or adjacent to the faceplate  22 . When the captive screw  16  is threaded into the threaded port  32 , the handle portion  26  of the latch assembly  12  is drawn towards and secured to the faceplate  22 , thereby preventing rotation of the pawl portion  28  of the latch assembly  12  and locking the housing  18  into the shelf assembly. When the captive screw  16  is backed out of the threaded port  32 , the opposite occurs. It will be readily apparent to those of ordinary skill in the art that other comparable mechanisms may be used to lock the housing  18  into the shelf assembly. The key aspect is that the actuation of the captive screw  16  or other locking mechanism, whether mechanical or electrical, correspondingly activates the switch (not illustrated) of the electronic fan brake (not illustrated). In this case, a portion of the captive screw  16  protrudes through the faceplate  22  and the threaded port  32 , and into the interior of the housing  18  where the switch of the electronic fan brake is located. 
         [0022]    In this exemplary embodiment, the captive screw  16  protrudes through the faceplate  22  and the threaded port  32  and engages a deflecting lever member  34  that, when deflected, engages the switch of the electronic fan brake. A first end  36  of the lever member  34  is coupled to the faceplate  22 , a second end  38  of the lever member  34  selectively contacts the electronic fan brake switch, and the locking mechanism  16  contacts the lever member  34  between the first end  36  and the second end  38  of the lever member  34 . The lever member  34  is described in greater detail herein below. 
         [0023]    Thus, the front of the cooling unit  10  ( FIG. 1 ) has a latch handle  26  and a captive screw  16  that are used by the operator to install and remove the cooling unit  10  from the shelf assembly. To install the cooling unit  10  in the shelf assembly and start the fans  14  ( FIG. 1 ) spinning, the latch handle  26  must be closed and the captive screw  16  must be fastened. It is not possible to operate the fans  14  under any other condition. To remove the cooling unit  10 , the captive screw  16  must be unfastened before the latch handle  26  can be rotated. The first few turns of the captive screw  16  release the switch, engaging the electronic brake on the fans  14 . By the time the captive screw  16  is completely unfastened, the fans  14  have stopped. 
         [0024]    The latch handle  26  is rotated to provide the force necessary to insert and remove the cooling unit  10  into and from the shelf assembly. When in the shelf assembly, the latch handle  26  is prevented from rotating by means of the captive screw  16 , which engages into the threaded port  32  of the cooling unit  10 . This prevents the cooling unit from being accidentally removed or dislodged from the shelf assembly. This type of latching system is not unusual in the industry, but the addition of the actuator mechanism makes the operation unique. 
         [0025]    When the captive screw  16  is engaged, it causes the lever member  34  to flex inwards. The first end  36  of the actuator  34  is fixed in position via a screw, but the second end  38  moves towards the switch mounted on a PCB assembly, which closes when the captive screw  16  is fully engaged. The fans  14  can only turn when the switch is closed, and when the switch is subsequently opened, the electronic brake on the fans  14  engages and the fans  14  spin down. It should be noted that the electronic brake is not instantaneous; the fans  14  take several seconds to stop rotating. 
         [0026]    To remove the cooling unit  10  while it is in operation, the captive screw  16  must be unfastened. The geometry of the actuator  34  is designed such that the switch opens and the electronic brake engages well before the captive screw  16  disengages and the latch handle  26  can rotate open and disengage from the shelf assembly, ensuring that the cooling unit  10  cannot be removed before the fans  14  have stopped rotating. 
         [0027]    This actuator mechanism is relatively small in size, is simple to assemble, and incorporates other useful features, such as a light pipe  40  (which makes an indicator LED visible through the faceplate  22 ) and a stop to prevent over travel from damaging the switch. The geometry of the actuator mechanism also allows it to trip a second redundant switch at the same time. These features are described in greater detail herein below. This design is more robust than placing the switches on cable assemblies, and it allows simple PCB mounted switches to be used, which are contained entirely inside the cooling unit  10 . The ability to choose favorable geometry for the region of the actuator mechanism that interfaces with the captive screw  16  means that considerable margin is present in the time between the disengagement of the switch and the moment at which a fan  14  is exposed to the operator. Although these captive screws  16  are generally rotated using hand tools, using a high speed drill or electric screw driver still does not expose the operator to a rotating fan  14 . Finally, the use of switches to engage the fans  14  means that it is not possible to defeat the actuator mechanism by simply latching the cooling unit  10  in place and leaving the captive screw  16  disengaged. The captive screw  16  must be fully engaged before the fans  14  will start to function. 
         [0028]      FIG. 3  illustrates the attachment of the first end  36  the lever member  34  to the faceplate  22  via a plurality of screws  42  and the deflection of the second end  38  of the lever member  34  with the actuation of the latch assembly  22 , showing both open and closed configurations. 
         [0029]    Referring now specifically to  FIG. 4 , in one exemplary embodiment, the lever member  34  includes a substantially planar portion  44  that defines a plurality of screw holes  46  by which the first end  36  of the substantially planar portion  44  is attached to the faceplate  22  ( FIGS. 1-3 ). A plurality of stiffening ribs  48  or the like are used to provide the substantially planar portion  44  with a predetermined degree of rigidity and prevent the substantially planar portion  44  from warping or twisting when actuated. A plurality of switch contact surfaces  50  are provided to engage the switches (not illustrated) of the electronic fan brake (not illustrated) when the substantially planar portion  44  is actuated. A plurality of stop structures  52  are provided to prevent over actuation of the substantially planar portion  44 . A plurality of holes  54  are formed in the substantially planar portion  44  in order to limit weight and material usage, and a contact recess  56  is provided to selectively receive the protruding portion of the captive screw  16  ( FIGS. 1 and 2 ). Finally, a light pipe  58  is provided to transmit light from the interior of the cooling unit  10  ( FIG. 1 ) and/or the shelf assembly (not illustrated) to the exterior of the faceplate  22  to indicate to the operator that the cooling unit  10  is fully engaged/disengaged, for example. All of the components of the cooling unit  10  and latch assembly  12  ( FIGS. 1-3 ) may be manufactured from a metal, a molded plastic, or any other suitably rigid material. It will be readily apparent to those of ordinary skill in the art that other suitable lever mechanisms or mechanisms for actuating the switches of the electronic fan brake may also be utilized. 
         [0030]    Referring now specifically to  FIG. 5 , in one exemplary embodiment, the PCB  60  of the cooling unit  10  ( FIG. 1 ) includes a plurality of redundant switches  62  operable for enabling/disabling the electronic fan brake (not illustrated), a LED  64  operable for illuminating the light pipe  58  ( FIG. 4 ), and a plurality of electrical connections  66 . Preferably, each of the switches  62  utilizes a depressible trigger mechanism or the like. 
         [0031]      FIGS. 6 and 7  illustrate the depression of the switches  62  by the latch assembly  12  and the captive screw  16 , thereby disabling the electronic fan brake and allowing the fans to spin up. 
         [0032]    Although the present invention is illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention, are contemplated thereby, and are intended to be covered by the following claims.