Abstract:
An outdoor lighting system utilizing light-emitting diodes (LEDs) and structures to dissipate heat generated by the LEDs. The system includes a tubular enclosure housing an internal LED lighting assembly including LEDs mounted to a finned support structure which extends between two ends of the tube. At the end of the tube is at least one heat dissipating structure which is retained on the tubular enclosure by the threaded fastener. A heat dissipating structure in the form of a finned heat sink having an integrated, formed-in-place gasket abutting the end of the tubular enclosure.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to a lighting system utilizing light-emitting diodes (LEDs) and, more particularly, to a substantially weather-sealed LED based lighting system with improved heat dissipation. 
       BACKGROUND 
       [0002]    Light emitting diodes (LEDs) have several major benefits compared to other lighting source. For example, LEDs typically have longer life spans than other comparable light emitting elements, such as incandescent lights or fluorescent lights. Moreover, LEDs are typically more energy efficient, compared to conventional light emitting sources. Thus, LEDs are incorporated into many applications where it is costly to operate and/or difficult to replace the light elements. Moreover, relative to size, an LED can produce a greater amount of light, measured in lumens, than a comparatively sized non-LED light. For this reason, LEDs have been incorporated into many applications requiring small-sized light elements. 
         [0003]    As an LED provides more light, the obvious corollary of greater light with respect to power consumption is that an LED wastes less power in the form of heat. Nonetheless, a large portion of generated heat is lost not on the light-emitting side of the diode, but instead at its circuitry base. The diode, which is an electrical circuit component, is typically mounted on a printed wiring or printed circuit board, referred to as a PCB. The heat generated by the diode is initially transferred to the PCB, and the PCB often includes a heat dissipation structure. For example, an 8-watt LED that includes proper heat dissipation may have a ten-year life span of daily 8-hour usage, while the same LED without proper heat dissipation may fail in approximately twenty minutes. 
         [0004]    With the substantial benefits afforded LEDs, efforts have been made to incorporate LEDs into pole or stanchion-type lights, such as outdoor lamps, street lights or lantern. In line with traditional approaches to construction, LED-based outdoor lights include an internal assembly that is mounted inside of an outer shell in order to protect the internal assembly from the elements of the weather. This internal assembly typically includes a main body formed of cast aluminum for the heat dissipation structure. However, when the internal assembly is mounted within its outer shell, the internal assembly is housed within a cavity of air within the shell, and the air acts as an insulator, thus impeding heat dissipation. Moreover, within a substantially weather-sealed LED, the weather-sealed structure retains heat and it is difficult to transfer heat from inside the weather-sealed structure of the LED lighting system to outside of such structure. The result is that this type of weather-sealed LED lighting system has poor heat dissipation. 
         [0005]    As a result, there is a need for an improved light assembly and, in particular, improved heat dissipation for use within substantially weather-sealed LED-based lighting systems. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    For the purpose of facilitating an understanding of the subject matter sought to be protected, there are illustrated in the accompanying drawings embodiments thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advantages, should be readily understood and appreciated. 
           [0007]      FIG. 1  is an exterior side view of a LED light system incorporating an embodiment of the present invention. 
           [0008]      FIG. 2  is cross-sectional side view of the LED light system taken along line  2 - 2  of  FIG. 1 . 
           [0009]      FIG. 3  is a cross-sectional view of the LED light system taken along line  3 - 3  of  FIG. 2 . 
           [0010]      FIG. 4  is an external side view of a LED light system incorporating another embodiment of the present invention. 
           [0011]      FIG. 5  is an external top plan view of the LED light system of  FIG. 4 . 
           [0012]      FIG. 6  is vertical cross-sectional side view of the LED light system depicted in  FIG. 4 . 
           [0013]      FIG. 7  is a perspective view of the internal components of the LED light system removed from the tube depicted in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    While the present invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail illustrative embodiments of the present invention with the understanding that the disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to embodiments illustrated. 
         [0015]    Referring to  FIG. 1 , a LED light assembly  10  designed for typical outdoor use is shown. In an embodiment, the LEDs components are housed within a substantially weather-sealed tube  12  having an internal cavity  12   a  ( FIG. 2 ). The tube  12  can be constructed of any type of weather-resistant material, such as, for example, acrylic, and is preferably transparent to allow easy light penetration. Referring also to  FIG. 2 , in an embodiment, the tube  12  includes first end  14  and second end  16 , each end  14 ,  16  includes respective openings  15   a ,  15   b  allowing access to the internal cavity  12   a  of the tube  12 . In an embodiment, the opening  15   a  in first end  14  is small than the diameter of the cavity  12   a . In an embodiment, the diameter of the opening  15   b  in second end  16  is substantially the same as the diameter of the cavity  12   a.    
         [0016]    At first end  14 , a fastener  18 , in the form of an ordinary bolt, for example, penetrates aperture  15   b  and is adapted to threadably engage internal threads  43  of support structure  42 . In an embodiment, the fastener  18  and tube  12  interface is substantially weather-sealed, such as with a gasket  20  constructed of an elastomeric material, such as, for example, silicone. The fastener  18  is preferably constructed of a thermally conductive material, such as, for example, a metal, to provide and enhance external thermal transfer of the heat extracted by the heat dissipation structure enclosed within the tube  12 , as discussed below. 
         [0017]    At second end  16 , a heat-dissipating spun cap  22  is coupled to the open end of tube  12 . In an embodiment, cap  22  is retained by a threaded fastener  32 . In an embodiment, threaded fastener  32  is adapted to be coupled to a mounting structure (not shown), such as, for example, a post or pole. The cap  22  is preferably constructed of a thermally conductive material such that the cap  22  is capable of transferring heat from the cavity  12   a  ( FIG. 2 ) of the lighting assembly  10  to the mounting structure and outside environment. In an embodiment, the cap  22  is generally U-shaped in cross-section and includes a peripheral flange  28  that is adapted to circumferentially extend beyond the outer edge of the aperture  15   b  of first end  14 . To provide a substantially weather-tight seal between the cap  22  and tube  12 , a gasket  30  may be circumferentially disposed in the opening of the tube  12  intermediate the tube  12  and the flange  28 . In an embodiment, the gasket  30  may be constructed of an elastomeric material, such as silicone or other water-sealing material. In an embodiment, the abutment between the cap  22  and tube  12  with gasket  30  substantially protects the internal component  13  of the LED light assembly  10  to an International Protection Rating (also known as an Ingress Protection Rating) of 65 (“IP65”) to ensure the proper protection from the ingress of external solids and liquids. 
         [0018]    As mentioned, a fastener  32  threadably retains cap  22  on the tube  12 . The fastener  32  includes a downwardly extending protrusion  32   a  which is adapted to axially penetrate a centrally disposed aperture  24  located in base  22   a  of cap  22 . In an embodiment, the threaded fastener  32  includes an axial channel  36  that is adapted to permit pass-through of wiring for the internal component  13  disposed within the tube  12 . In an embodiment, a substantially weather-tight gasket  38 , such as a gasket constructed of an elastomeric material, such as silicone, is disposed between a circumferential lip  40  of fastener  32  and the cap  22 . Downwardly extending protrusion  32   a  of fastener  32  includes threads  35  adapted to penetrate and engage internal threads disposed in channel  44  of support structure  42 . Fastener  32  maintains engagement between support structure  42  and base  22   a  of cap  22  to thermally couple internal component  13  to external environment via cap  22 . As such, configuration of support structure  42  within cavity  12   a  of tube  12  is maintained by fasteners  32  and  18 . 
         [0019]    Disposed within the cavity  12   a  of tube  12  is the internal component  13  which includes a LED and a support structure  42  axially extending between ends  14  and  16  of the tube  12  and adapted to support LEDs  54 . In an embodiment, the LEDs  54  are mounted on a printed wiring or printed circuit board  55  and the circuit boards  55  are secured to the exterior of support structure  42  by a screw  56  and washer  57 . Washer  57  may be constructed of silicone or other suitable material to provide over-torque protection to the assembly and prevent damage to the circuit board  55  by screw  56 . The support structure  42  is preferably constructed of material capable of effectively dissipating heat, such as, for example, aluminum. The support structure  42  is preferably hollow, having an axial cylindrical channel  44  extending the length of the support structure  42 . The channel  44  includes receiving threads  34  on the inner surface thereof for threadable engagement with the threads  35  and  43  of fasteners  32  and  18 , respectively. 
         [0020]    At end  16  adjacent the spun cap  22 , a connector  59 , such as, for example, a Tyco Surface Mount Technology connector or equivalent, is mounted to the external surface of support structure  42 . Connector  59  accepts the wiring passing through axial channel  36  of fastener  32 , connecting the wiring to the printed circuit boards  55 . A plurality of connectors  59  may be mounted on sides of the support structure  42 . 
         [0021]    Referring also to  FIG. 3 , the support structure  42  includes generally planar exterior walls  46 , and an internally cylindrical channel  44 . In cross-section, the support structure  42  may be generally rectangular, triangular, or other suitable shape. On the exterior walls  46  of the support structure  42  are mounted one or more LEDs  54 . In an embodiment, at the intersecting corners of the exterior walls  46  are laterally extending protrusions  50  offset by a corresponding groove  52 . The fins  50  and groove  52  increase the surface area of the support structure  42 , thereby increasing heat dissipating capacity to the internal component  13 . Though depicted with two fins  50  and a single groove  52 , it will be appreciated that the present invention may include a plurality of grooves  52  and corresponding fins  50  to increase the surface area of the support structure  42 . 
         [0022]    In an embodiment, when assembled, a first end  45  of the support structure  42  abuts the cap  22  to increase heat dissipation. The heat extracted from the LEDs by the support structure  42  is transferred to the cap  22  via thermal conduction. The cap  22  may then transfer the heat to a mounting structure (not shown) of the LED light assembly  10 , or dissipate the heat via air. 
         [0023]    Referring now to  FIGS. 4-6 , in another embodiment, the internal component  413  is adapted to retain one or more LEDs and may include two heat-dissipating structures disposed at either first end  414  and/or second end  416  of tube  412 , which retains the internally disposed internal component  413  therebetween. The heat generated by the internal LEDs  454  coupled to the LED assembly  413  is vertically extracted by support structure  442  and externally dissipated at ends  414  and  416  of the assembly  410 , thereby increasing the performance and longevity of the LEDs  454 . 
         [0024]    As shown in  FIGS. 4-6 , the tube  412  is generally cylindrical. As in the embodiment depicted in  FIG. 1-FIG .  3 , disposed within the cavity  412   a  of tube  412  is internal component  413  which includes a support structure  442  axially extending between ends  414  and  416  of the tube  412  and adapted to support the LED light elements  454 . The support structure  442  is preferably constructed of material capable of effectively conducting heat, such as, for example, aluminum. The support structure  442  is preferably hollow, having an axial cylindrical channel  444  extending the length of the support structure  442 . The channel  444  includes receiving threads  434  on the inner surface thereof for threadable engagement with the threads  435  and  437  of fasteners  432  and  476 , respectively. 
         [0025]    At second end  416 , a heat-dissipating spun cap  422  is coupled on the open end of the tube in the same manner as spun cap  22  in the prior embodiment depicted in  FIG. 1-FIG .  3 . In an embodiment, the cap  422  is retained by a threaded fastener  432 . In an embodiment, threaded fastener  432  is adapted to be coupled to a mounting structure (not shown), such as, for example, a post or pole. The cap  422  is preferably constructed of a thermally conductive material such that the cap  422  is capable of transferring heat from the support structure  442  and cavity  412   a  of the lighting assembly  410  to the mounting structure and external air. The cap  422  is coupled to an end of the support structure  442  and retained thereon with a hollow threaded fastener  432  and a substantially weather-tight gasket  438  disposed between a circumferential lip  440  of fastener  432  and the cap  422 . The gasket  438  is preferably constructed of an elastomeric material, such as silicone. In an embodiment, the abutment between the cap  422  and tube  412  substantially protects the internal component  413  of the LED light assembly  410  to an International Protection Rating of 65 (“IP65”) to ensure the proper protection from the ingress of external solids and liquids. 
         [0026]    At first end  414  of tube  412 , a heat dissipation structure  470  is coupled to the support structure  442  and includes a plurality of fins  472  that increase the surface area of heat dissipation structure  470 . Heat dissipation structure  470  is coupled to the support structure  442  via a heat sink mounting plate  474  at a proximal end  475  of the heat dissipation structure  470 . The heat dissipation structure  470  is coupled to the assembly  410  by a threaded fastener  476  received through a centrally disposed aperture  478  in the mounting plate  474 . In an embodiment, a gasket  482 , preferably constructed of an elastomeric material, such as silicone, is disposed between the fastener  476  and the mounting plate  474  to provide a weather-tight connection. Fastener  476  includes a downwardly protruding portion  476   a  adapted to penetrate axial cylindrical channel  444  of support structure  442 . Fastener  476  is threadably coupled to end  447  of channel  444  via threads  437 . Fastener  476  thereby maintains engagement between support structure  442  and mounting plate  474  to thermally couple the support structure  442  and cavity  412   a  to external environment. In an embodiment, fastener  476  is preferably composed of a thermally conductive material, such as, for example, a metal, to provide and enhance external thermal transfer of the heat extracted by the heat dissipation structure enclosed within the tube  412 . 
         [0027]    In an embodiment, the underside  474   a  of heat sink mounting plate  474  includes a circumferential groove  490 . The groove  490  is adapted to have a diameter substantially similar to the diameter of the tube  412  so that the tube  412  end can be inserted therein and friction fitted therewith. In an embodiment, a gasket  492 , preferably constructed of an elastomeric material, such as silicone, is disposed within groove  490  to provide a substantially weather-tight interface. The groove  490  is adapted to retain the edge of the open end of the tube  412 , wherein the gasket  492  substantially weather-seals the connection between the mounting plate  474  of the heat sink  470  and the tube  412 . An integrated heat sink and gasket assembly provides added protection by eliminating possible misalignment between the gasket and the edge of the acrylic tube  412 . In an embodiment, the abutment between mounting plate  474  and tube  412  substantially protects the internal component  413  of the LED light assembly  410  to an International Protection Rating of 65 (“IP65”) to ensure the proper protection from the ingress of external solids and liquids. 
         [0028]    The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. While particular embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the broader aspects of applicants&#39; contribution. The actual scope of the protection sought is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.