Abstract:
A multi-latch compatible system is disclosed for electrical enclosures. The system accommodates latches of different types and configurations. A rail structure may be formed to interface with pin-type latches and with plate-type latches. The rail structure may be configured as a pre-assembled insert that can be placed within an electrical enclosure. The system permits the same general structure to be used regardless of the type of latching mechanism selected and installed in the enclosure.

Description:
BACKGROUND 
   The present invention relates generally to the field of electrical enclosures. More particularly the invention relates to mechanisms for latching electrical enclosures in a closed position to house power electronic and other electrical circuit components within a controlled volume. 
   A wide range of applications exist for electrical enclosures of all types. Such enclosures are used heavily in industry, but also in mobile applications, offshore applications, consumer and commercial applications, and so forth. In general, electrical enclosures typically include a shell or box made of a heavy gage sheet metal. The enclosures are configured to support electrical circuitry and electrical components therein, and to receive and send electrical power and data signals. The internal components of the enclosure are accessible through doors, hatches and other openings. An important feature in such enclosures is that the doors can be readily opened, but closed and latched securely to prevent intrusion or tinkering with the components in an unauthorized manner. 
   A range of mechanical latch mechanisms have been developed for electrical enclosures. These often include various types of handles, some of which may be locked into position, or that may permit physical lock-out by means of a pad lock or other security device. One type of latching device makes use of a bayonet-type pin arrangement that offers advantages over more traditional latches. For example, such arrangements have been made that permit venting of gasses from the enclosure in the event of an electrical fault. 
   A drawback in the development of electrical enclosures has been the variety in the designs of the latching mechanisms. In general, the door, and particularly the internal structures of the enclosures may require completely different designs to accommodate the type of latch selected by a user. Little or no cross-over of these designs has taken place in the field. Accordingly, the entire enclosure assembly is most often selected from the outset, with little or no ability to adapt the enclosure for different latch types where desired. For manufacturers, then, such variety leads to additional costs in manufacturing, stocking and assembling different enclosure structures to accommodate the different latches. 
   There is a need, therefore, for a more universal system for latching electrical enclosures. There is, in particular, a need for a system that will accommodate various commercially available latch-types, and permit the use of these latch types in a cost-effective universal enclosure design. 
   BRIEF DESCRIPTION 
   The invention provides a novel electrical enclosure designed to respond to such needs. In general, the enclosure forms a shell that encloses an interior volume for housing electrical components. A door is hinged to the shell for closing the interior volume. A latch plate is configured to interface with a latching element of a first configuration that can be secured to the door to hold the door closed on the shell. A second latch plate is then configured to interface with a latching element of a second configuration that can be used with the door. 
   In a particular implementation disclosed below, one of the latch plates is designed to accommodate a latch pin-type latching element. An aperture is thus provided in the first latch plate to permit passage of the pin, which may then be latched by turning the pin in the door. In a present embodiment the second latch plate essentially comprises a rail behind which a latching element of the second configuration is disposed during latching. The latching element may be a plate-type rotatable component that is moved by a pin or handle. 
   The latching arrangement within the enclosure, comprising both latch plates may be configured as an insertable unit. That is, the plates may be part of an assembly that is securable within the enclosure shell, thereby permitting both types of latches to be accommodated in a simple and cost-effective manner. 

   
     DRAWINGS 
     These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
       FIG. 1  is a perspective view of an exemplary electrical enclosure incorporating a latching system in accordance with aspects of the present invention; 
       FIG. 2  is a detailed view of a portion of the system of  FIG. 1  illustrating an exemplary manner in which a pin-type latching mechanism may be accommodated by a corresponding latch plate; 
       FIG. 3  is a similar detailed view of a portion of the system of  FIG. 1  illustrating how a plate-type latch mechanism may be accommodated by a rail member of the system; 
       FIG. 4  is a partial elevational view of a latch plate assembly designed as an insert for an enclosure and incorporating a series of latch plates or latching surfaces of the type illustrated above; 
       FIG. 5  is a top perspective view of a portion of the assembly of  FIG. 4 ; 
       FIG. 6  is a partial front perspective view of the assembly of  FIGS. 4 and 5 ; 
       FIG. 7  is a partial sectional view looking downwardly on a door of an enclosure latched via the system illustrated in the previous figures by use of a pin-type latch; and 
       FIG. 8  is a view similar to that of  FIG. 7  but illustrating the same enclosure closed via a plate-type latch mechanism. 
   

   DETAILED DESCRIPTION 
   Turning now to the drawings, and referring first to  FIG. 1 , an enclosure  10  is illustrated on which a multi-latch compatible system  12  is installed. The enclosure may be any suitable type and size. In the illustrated embodiment, for example, the enclosure may house an industrial motor control center. The enclosure generally includes a shell  14  which, in the illustrated embodiment, is divided into compartments  16 , each having a corresponding door  18 . The doors  18  may be opened and closed to gain access to an interior volume  20 . 
   It should be noted that the present techniques are in no way limited, however, to any particular enclosure type or style. The invention will find application with enclosures made of conventional sheet metal, but may also be used with fiberglass enclosures, plastic enclosures, and so forth. The multi-latch compatible system described below may also be suitable for enclosures with a single door or with multiple doors and compartments. Similarly, the system may be used with enclosures designed to house both power electronic components, with or without data (e.g., computer) components, or with data components alone. Finally, the enclosure may be of a sealed type, or may be vented and unsealed, as desired. 
   In the embodiment illustrated, enclosure  10  further includes a wireway  22  over which a door  24  may be closed. As will be appreciated by those skilled in the art, electrical system components are typically disposed within the interior volume  20  of the compartments, while power and communication wiring may be routed through the wireway. 
   In the embodiment illustrated in  FIG. 1 , each door, such as open door  26 , is provided with latches that interface with the multi-latch compatible system  12  to hold the doors closed. As described in greater detail below, door  26 , for example, is provided with pin-type latches  28 . Other doors may be provided with plate-type latches  30 . Many such latches are known and are commercially available. In general, the present system permits multiple different types of latches to be provided on the doors, while all interfacing with the same multi-latch compatible system  12  installed in the enclosure shell. 
   As shown in  FIG. 1 , and as described in greater detail below, the system  12  generally includes a rail structure  32  that may be installed as an insert in the enclosure shell. The rail structure itself will include surfaces, apertures, and mechanical structures for receiving and interfacing with multiple different latch types. In the illustrated embodiment, for example, the rail structure has a rail  34  through which apertures are formed. Behind these apertures  36 , the rail  34  has openings (described below) for receiving pin-type latches. A plate or rail  38  is also included in the rail structure for interfacing with plate-type latches. It may also be noted that in the illustrated embodiment, extensions  40  are provided on the rail structure (described in greater detail below) for accommodating latches for the wireway door  24 . All of the latches may thus be accommodated by a single assembly fixed within the enclosure shell. 
     FIG. 2  illustrates an exemplary configuration of the system of  FIG. 1  for accommodating a pin-type latching device. As shown in  FIG. 2 , the rail structure  32  of the system includes a front plate  42  through which apertures  36  are formed. Behind plate  42 , and accessible through aperture  36 , rail  34  presents an aperture  44  designed to receive the pin of a pin-type latch. In the illustrated embodiment, the aperture  44  has a central portion  46  flanked by elongated wings  48 . 
   As will be appreciated by those skilled in the art and familiar with pin-type latches used in industry, an exemplary pin-type latch as shown in  FIG. 2  has a central pin or shank  50  designed to be loaded in tension when the enclosure is closed. The pin in the illustrated embodiment receives a roll pin  52  near its extremity. The roll pin is loaded, when latched, in double shear against a rear surface of the rail  34 . A spring  54  is disposed around the pin  50  between the outer surface of the enclosure door (as shown in dashed lines in  FIG. 2 ) and a head  56  of the pin. To latch the door, then, the pin is rotated such that the roll pin  52  aligns with wings  48  of the aperture  44 , and the spring is depressed to permit the roll pin to clear the rail  34 . The pin is then rotated to block the roll pin  52  behind the rail  34 . It should also be noted that the roll pin may be lodged within recesses formed in the rail to aid in retaining the roll pin in position behind the rail  34  against the force of spring  54 . Also, a seal (not shown) may be provided on the pin at a point where the pin penetrates through the door of the enclosure. 
     FIG. 3  shows the same system used with a plate-type latch mechanism. As shown in  FIG. 3 , the plate-type latch  30  includes a generally Z-shaped plate  58  that presents a tongue or extension  60  for latching the door. A pin or bolt  62  is secured to the latch plate and has a shank  64 , one or more sides of which presents a flat  66 . An aperture in the latch plate receives the shank of the pin, with the flat  66  mating with a corresponding flat in the latch plate. At an outer end, the pin has a head  68 , and at an opposite end a threaded tip (no shown) on which a fastener  70  is secured. The latch plate will typically abut a shoulder (not specifically shown in  FIG. 3 ) on the pin to securely hold the latch plate in position on the pin once the fastener is anchored onto the end of the pin. As in the previous arrangement, a seal may be provided on the pin at a point where the pin will traverse a door of the enclosure. 
   For closing the arrangement of  FIG. 3 , the tongue  60  of the latch plate will be positioned in a vertical orientation such that the latch plate will freely traverse the aperture  36  in front plate  42 . Once the door is closed and the plate is past the rear surface of front plate  42 , the pin may be rotated to secure the latch plate extension  60  behind the side plate  38  (as shown in dashed lines in  FIG. 3 ). 
     FIG. 4  illustrates a portion of the multi-latch compatible system  12  embodied as an insert to be secured within the shell of an enclosure. As mentioned above, the insert generally forms a rail structure  32  that may span several compartments of a multi-compartment enclosure. The rail structure illustrated is formed of a main rail  72  which may be made of sheet metal that is stamped and bent to form the front plate  42 . Apertures  36  are also punched or cut into the main rail prior to bending. The main rail thus presents a side panel  74  which may be provided with rungs  76  or similar structures that aid in supporting other components, shelves, and so forth (not shown), within the enclosure. 
   As illustrated in  FIG. 4 , the bent front plate  42  thus presents a series of apertures  36 , seen from the rear in  FIG. 4 . The rail  34  designed to accommodate the pin-type latch mechanisms is, in the illustrated embodiment, added as a separate component. In the present embodiment this rail also is stamped from sheet metal and apertures  36  are cut at the time of formation of the rail. Tabs  78  are provided at locations of the rungs  76  of the main rail  72 . These tabs permit the rail  34  to be welded to the main rail  72  during assembly, or attached by means of fasteners (e.g., screws, bolts or rivets). Various other rails and structures may be provided in the system. For example, in the illustrated embodiment, a stiffening member  80  is also welded to the side panel  74  of the mail rail  72 . Such members may further facilitate securement of panels, shelves, and other structures (not shown) within the enclosure. 
     FIGS. 5 and 6  are additional views of the rail structure both before and after installation in an enclosure. Both views illustrate the main rail  72  described above, with its side panel  74 . The rungs  76  are again shown as they may be disposed within the enclosure for supporting internal components. The illustrated views of  FIGS. 5 and 6  also show the extension  40  which is provided as part of rail  34 , and may in the illustrated embodiment facilitate latching of a wireway door. 
     FIGS. 7 and 8  illustrate the foregoing multi-latch compatible system in place for holding a door closed on an enclosure with both a pin-type latch mechanism and a plate-type mechanism, respectively. As shown in  FIG. 7 , once latched, the pin  50  of mechanism  28  extends through the aperture  44  in rail  34 . The pin is illustrated as it would rotated to cause roll pin  52  to abut a rear surface of the rail  34 . It should also be noted that both the pin and the accompanying roll pin may be freely inserted through aperture  36  in the plate  38 . The biasing spring  54  then holds the pin in tension and the roll pin in double shear. A flange of the front door  26  abuts the front surface of plate  38  as shown. Where desired, a seal or gasket (not shown) may be provided, such as between the plate  38  and the flange of door  26 . 
   As illustrated in  FIG. 8 , when a latch plate-type latch is employed, rail  34  generally does not come into play. Rather, the tongue  60  of the latch plate  58  is rotated behind the plate  38  of the rail structure and abuts the rear plate to hold the assembly tightly in engagement. Again, a flange of door  26  then abuts the front surface of plate  38 , where a gasket may be provided, where desired. Seals, O-rings, or other compression members may also be provided between the head  68  of the latch pin  62  and a front surface of the door  36 . 
   While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.