Abstract:
A removable cover for a an electrical component box includes a pair of side walls having hinge edges including a hook and an engagement surface extending from the hook. The hook slides over and engages the hinge members of a box, and the engagement surface forms a sliding surface that allows rotation of the cover about the hinge elements. The hinge is easily installed and removed by orienting the cover at a selected angle relative to a longitudinal axis of the box, and lifting the hook over the hinge member to either engage or disengage the hook from the hinge members.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to housing constructions for electric witches and components, and more particularly, to a lock box housing for air conditioning disconnect switches. 
     One type of known box housing for disconnect switches typically used in air conditioning systems includes a cover or door that pivotally opens upon hinge elements formed into upper side walls of the box. The cover rotates upwardly about the hinge elements, and may be retained in an open position by inserting a leading edge of the cover into slots formed into the side walls of the box. The cover is selectively positionable between the open position allowing access to an interior of the box, and a closed position that protects the contents of the box from the elements. To prevent unauthorized access to the box, a lock opening formed in a bottom end of the box protrudes through a slot in a lower end of the cover, and a lock mechanism such as a padlock, is inserted through the lock opening to prevent opening of the box. 
     Conventional covers for this type of box include an oblong closed slot in upper ends of each side wall of the cover. The box and cover are assembled so that the slots formed into the cover side walls contain the box hinge elements. As the cover is rotated about the box hinge elements, the relative position of the hinge elements in the closed slot is changed. The slots accommodate the hinge elements as the cover is moved between the open and closed positions. This assembly, however, is not amenable to removal of the cover from the box. 
     It has been observed in the field that workers sometimes pry or bend the cover side walls and the box side walls apart to free the closed cover slots from the box hinge elements. The cover may then be removed from the box for maximum access to the box interior to complete installation, wiring, and service repair of the contents of the box. Removal of the cover in this fashion is problematic. 
     Accordingly, it would be desirable to provide a cover for a pull out switch box that may be easily removed and reinstalled in the field. 
     BRIEF SUMMARY OF THE INVENTION 
     In an exemplary embodiment of the invention a removable cover for an electrical component box includes a pair of side walls having hinge edges for removable engagement with hinge members formed into the side walls of the box. Specifically, the hinge edges include a first portion forming a hook and a second portion adjacent the first portion and extending substantially parallel to a flat front face of the cover. The hook slides over and engages the hinge members of the box, and the second portion of the hinge edge forms a sliding engagement surface that allows rotation of the cover about the hinge elements. 
     The hinge is easily installed and removed by orienting the cover at a selected angle relative to a longitudinal axis of the box, and then lifting the hook over a the hinge member to either engage or disengage the hook from the hinge member. At angles substantially different from the selected angle, the cover remains attached to the hook and/or second portion of the cover hinge edges. A lock slot in a lower end of the cover slips over a lock bracket formed in a lower end of the box, and the box may be locked in a closed position by inserting a lock member, such as a padlock, through a lock opening in the lock bracket. 
     The cover may be retained in the open position by inserting the leading edge of the cover into slots in the box side walls, thereby allowing access to the box while the cover is attached to the box. When maximum access is desired, however, the cover may be completely removed from the box without damaging bending or prying of the box and cover, and the cover may be reattached in its original shape and position, thereby maintaining the integrity and appearance of the box 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is perspective view of a lock box including a removable cover in an open position; 
     FIG. 2 is a perspective view of the box shown in FIG. 1 with the cover removed; 
     FIG. 3 is a partial plan view of a portion of the box shown in FIG. 2; 
     FIG. 4 is a side elevational view of the cover shown in FIG. 1; and 
     FIG. 5 is a side elevational view of a second embodiment of a removable cover for the box shown in FIGS.  1 - 3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is perspective view of a lock box  10  for electrical components (not shown). While the embodiment of the invention described herein relates to use in a secure housing for a disconnect switch (not shown), such as those used in air conditioning systems, it is contemplated that the benefits of the invention extend well beyond this particular application. More specifically, it is contemplated that the instant invention may be used in conjunction with a large variety of pull out switches, and even more generally in conjunction with a large variety of panel boards. Therefore, the invention is not intended to be restricted to the specific application of housing air conditioning disconnect switches. 
     Box  10  includes a bottom wall  12 , opposite side walls  14  extending from bottom wall  12 , a rear wall  16  extending between box side walls  14 , and a top section  18  attached to box side walls  14  and to said rear wall  16 . Rear wall  16  includes mounting openings (not shown) for mounting of the box and/or electrical components (not shown) therein. A removable cover  20  is attached to box side walls  14  in a manner described firer below. Cover  20  includes opposite side walls  22 , a lock end  24 , and a front fare  26  including a hollow shroud  28  upwardly depending therefrom for housing a disconnect switch (not shown) or other electrical component (not shown) having a lateral dimension larger than a width W of box side walls  14 . Cover lock end  24  includes a slot  30  that fits over a lock bracket  32  integrally formed into box bottom wall  12 . A lock opening  34  in lock bracket  32  is dimensioned to accept a lock member or lock mechanism (not shown), such as a padlock to prevent unauthorized access to a box interior  38 . 
     Cover  20  is movable between an open position (shown in FIG. 1) and a closed position (not shown). In the open position, a leading edge (not shown in FIG. 1) of cover  20  is received in slots (not shown In FIG. 1) formed in box side walls  14  to maintain cover  20  at a slight upward angle relative to box  10 . In the closed position, cover side walls  22  overlap box side walks  14 , and a bottom lip  36  of cover  20  overlaps box bottom wall  12  to seal box interior  38 . Cover  20  rotates upon hinge members (not shown in FIG. 1) between the open and closed positions, and cover  20  is removable from the hinge members as desired by a user. 
     FIG. 2 is a perspective view of box  10  illustrating a slot  50  formed in an upper end  52  of each box side wall  14  to receive a leading edge (not shown in FIG. 2) of removable cover  20  (shown in FIG. 1) and maintain cover  20  in the open position. A hinge member  54  is located adjacent each slot  50  for engagement with a hinge end (not shown in FIG. 2) of removable cover  20 . In a particular embodiment, hinge member  54  is an extruded post or knob projecting from an inner surface  56  of box side walls  14 . Box  10  is symmetrical about a longitudinal axis  58 , and each of box side walls  14  is a mirror-image of the other. 
     FIG. 3 is an enlarged plan view of a top comer of box  10  illustrating a connection of box side wall  14  with top section  18 . A rounded protrusion  70  projects from an outer surface  72  of box side wall  14  and is attached to a side wall  74  of top section  18  with a know connector (not shown), such as, for example a rivet. Protrusion  70  spaces top section side wall  74  from box side wall  14  to form a gap  76  therebetween that receives a hinge end (not shown in FIG. 3) of removable cover  20  (shown in FIG.  1 ). Hinge member  54  also projects from box side wall outer surface  72  into gap  76 , but does not contact top section side wall  74 . In one embodiment, hinge member  54  includes a rounded surface  78  to facilitate sliding of the hinge end of removable cover  20  upon hinge member  54 . 
     FIG. 4 is a side elevational view of removable cover  20  illustrating hinge end  90  opposite lock end  24  on cover side wall  22 . Cover side wall  22  is defined by an inner edge  92  extending substantially perpendicular from cover front face  26  and toward an outer edge  94 . Hinge end  90  includes a hook  96  that is positioned approximately halfway between inner edge  92  and outer edge  94 . Hook  96  includes a chambered edge  98  adjacent a leading edge  100  of removable cover  20 , a substantially flat edge  102  adjacent chambered edge  98 , and a rounded portion  104  for engaging box hinge member  54  (shown in FIGS.  2  and  3 ). A substantially flat or straight engagement surface  106  extends rearwardly from hook rounded portion  104  to a stop surface  108  extending substantially perpendicularly to engagement surface  106  and cover outer edge  94 . In use, hinge member  54  is engaged to cover engagement surface  106  and cover  20  slides upon hinge member  54  between hook rounded portion  104  and stop surface  108  to place cover  20  in the closed and open position, respectively. 
     Hook  96  is located between cover inner edge  92  and outer edge  94  to facilitate insertion and removal of hook  96  into gap  76  (shown in FIG. 3) and over box hinge member  54  (shown in FIG.  3 ). In one embodiment, hook  96  is located approximately equidistant between inner edge  92  and outer edge  94  so that cover  20  may be removed from box  10  (shown in FIG. 2) when cover  20  is oriented at an angle of about 55° with respect to box longitudinal axis  58  (shown in FIG.  2 ). At angles substantially different from about 55°, cover  20  remains engaged to hook  96  and/or engagement surface  106  adjacent hook  96  of each hinge edge  90 . In alternative embodiments, other shapes and locations of hooks are used that require greater or lesser than about a 55° angle of inclination with respect to box longitudinal axis  58  for installation and removal of cover  20  to and from box  10 . 
     FIG. 5 is a side elevational view of a second embodiment of a removable cover  110  similar to cover  20  shown in FIGS. 1 and 4 but including a rounded notch  112  forming a stop surface  114  for hinge members  54  (shown in FIGS.  2  and  3 ). Notch  112  is defined by an end surface  116  extending substantially perpendicular to engagement surface  106 . 
     Either cover  20  or cover  110  may be removed from box  10  quickly and easily without damaging box  10  and without impairing the open and closed positions of the cover with respect to box  10 . Therefore, the aesthetic appeal of box  10  is maintained and the security of box  10  is unaltered after removal of the cover. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.