Patent Publication Number: US-2017363261-A1

Title: Recessed downlight with integral junction box

Description:
FIELD OF THE INVENTION 
     The invention relates to a recessed downlight that integrates a light engine assembly with a junction box containing the driver assembly. 
     BACKGROUND OF THE INVENTION 
     Recessed, flush-mounted downlights are suitable for mounting in soffits, above drywall, or above a dropped ceiling. These luminaires include a housing, trim, and a lamp. Various types of lamp are known, including incandescent, high-intensity discharge, compact fluorescent, and light emitting diodes (LEDs). 
     Some of these lamps do not operate at traditional line voltages, but rather require transformers, ballasts, or other electronics. These other components are frequently mounted in an isolated but connected junction box. 
     The light engine assembly and driver assembly are typically mounted separately, with the components connected electrically. This electrical connection can be cable routed through the air or a cable routed through flexible conduit. However, such an installation is governed by applicable safety codes, which for example require consideration of the presence or absence of flammable materials, such as insulation. 
     To better facilitate installation and to meet safety codes, there is a requirement for an improved recessed luminaire based that mechanically connects the light engine assembly with the junction box containing the driver assembly, minimizing the external wiring between these components and enhancing code compliance. 
     SUMMARY OF THE INVENTION 
     The present invention provides a recessed luminaire that integrates the light engine assembly with the junction box containing the driver assembly. This facilitates installation of the luminaire, while meeting the strict safety codes required in certain jurisdictions, such as Underwriters Laboratories 1598, “Standard for Safety for Luminaires” (Third Edition, Sep. 1, 2008). 
     One challenge of developing an integrated luminare is to develop a mounting configuration that is flexible enough to accommodate a range of installations from very thin  28  gauge sheet metal soffits to ⅝″ thick drywall or a drop ceiling. The solution of the present invention is, in one embodiment, a single torsion spring at an end of the light engine assembly remote from its connection to the junction box, while a leaf spring attaches to the junction box near its connection to the light engine assembly. In a second embodiment, the leaf spring is integrated into an extension of the junction box. The leaf spring allows for a high-enough tension to hold the light unit assembly in place in thin sheet metal, while allowing for a low-enough tension to accommodate holding the light unit assembly in place in drywall or a drop ceiling. 
     The luminaire configured and arranged as described can be constructed using any known combination of materials. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the invention are described herein below with reference to the drawings wherein: 
         FIG. 1  illustrates a luminaire designed for recessed installation; 
         FIG. 2  is another view of the luminaire designed for recessed installation; 
         FIG. 3  is an exploded view of the light engine assembly and a partially exploded view of the driver assembly; 
         FIG. 4  is an exploded view of the driver assembly; and 
         FIG. 5  is a plan view of the luminaire. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 1 and 2 , there is illustrated a preferred embodiment of the present invention in which the luminaire  1  includes a light engine assembly  2  and a driver assembly  3 . Light engine assembly  2  and driver assembly  3  are mechanically connected through mechanical connector  6 . As is known in the art, mechanical connector  6  can be a permanent connector, such as a weld, or can be a removable connector, such as a connection made by screw, nut and bolt, and so forth. For ease of shipping, it is especially advantageous for mechanical connector  6  to be a removable connector. In one embodiment, a hinge is incorporated into mechanical connector  6  to provide for rotational flexibility in the mechanical connection between light engine assembly  2  and driver assembly  3 . 
     Light engine assembly  2  and driver assembly  3  are electrically connected through electrical connector  7 . As is known in the art, electrical connector  7  can be a single cable that at a first end terminates at light engine assembly  2  and at a second end terminates at driver assembly  3 , with the terminations made via a terminal block, or a plug-in connector, or a twist-lock pin and sleeve connector, or via other connectors known in the art. Alternatively, electrical connector  7  can be two cables and a two-part connector, such that the first cable terminates at a first end at light engine assembly  2  and at a second end terminates at a first part of the two-part connector, with the second cable that terminates at a first end at driver assembly  3  and at a second end terminates at the second part of the two-part connector. 
     A single torsion spring  4  is installed in light engine assembly  2  at a far end from the mechanical connector  6  joining light engine assembly  2  to the junction box of driver assembly  3 . Driver assembly  3  incorporates a leaf spring  5  that attaches to the junction box of the driver assembly  3 , or else that is integrated into an extension of the junction box, with leaf spring  5  being positioned in close proximity to mechanical connector  6 . As discussed above, the leaf spring allows for a high-enough tension to hold the light unit assembly in place in thin sheet metal, while allowing for a low-enough tension to accommodate holding the light unit assembly in place in drywall or a drop ceiling. 
       FIG. 3  illustrates one embodiment of the invention showing exploded views of light engine assembly  2 . 
     Light engine assembly  2  includes a trim piece  301  and foam gasket  302 , which will contact the material against which luminaire  1  is installed, such as a sheet metal soffit, drywall, or a drop ceiling. Torsion spring  4  attaches to trim piece  301 . 
     Mounted inside trim piece  301  is an optical diffuser  303 , and printed circuit board assembly (PCBA)  305 , on which are installed light emitting diodes, is installed within trim piece  301  and held in place with thermal adhesive  304 . Light guide  306  and reflective film  307  are also installed within trim piece  301 . The aforementioned components within trim piece  301  are secured in place by rear cover plate  308 , which is attached to trim piece  301 , such as with screws or bolts. 
       FIG. 3  also shows an exploded view of driver assembly  3 , for which additional details are shown in  FIG. 4 . In the embodiment shown, mounting cover  310  forms the largest component of the junction box housing the driver assembly  3 . Wiring cover  312  is removable, providing access to terminal blocks  316 , which are provided for termination of electrical supply conductors. Wiring cover  312  is secured in a closed position with lock spring  317 . A removable side plate  311  allows access to the driver electronics  315 , for which insulation paper  314  is supplied. Wiring clip  313  is provided for securing electrical connector  7  to the exterior of mounting cover  310 . 
     Leaf spring  5  attaches to mounting cover  310  in the embodiment shown. As discussed previously, in another embodiment it is integrated into an extension of the junction box. 
     In a preferred embodiment, mechanical connector  6  provides for a vertical offset between light engine assembly  2  and driver assembly  3 , such that the bottom of driver assembly  3  is at a horizontal plane that is higher than the horizontal plane of the bottom of light engine assembly  2 . For example, this allows trim piece  301  at the bottom of light engine assembly  2  to be mounted within a drywall ceiling, with the vertical offset allowing the bottom of driver assembly  3  to be positioned within the ceiling cavity and allow for mounting into material thicknesses ranging from 28 gauge sheet metal through ⅝″ drywall. Or alternatively, trim piece  301  can be mounted within a drop ceiling, with the vertical offset allowing the bottom of driver assembly  3  to clear the top of the runners and cross-ties supporting the drop ceiling. 
       FIG. 5  illustrates another preferred embodiment, in which a centerline  501  of the driver assembly  3  intersecting the light engine assembly  2  is placed at an angle, preferably greater than 10°, to a centerline  502  of the light engine assembly  2  that passes through torsion spring  4  and leaf spring  5 . This allows for greater flexibility in mounting luminaire  1  in a ceiling such that light engine assembly  2  is positioned in the desired location while allowing driver assembly  3  to avoid a joist or other obstruction that may be present within the ceiling cavity. 
     While preferred embodiments of the present invention have been illustrated and described herein, it will be apparent that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will be apparent to those skilled in the art without departing from the invention, the scope of which is to be determined by the following claims.