Patent Publication Number: US-9851081-B2

Title: Wedge shaped heat sink for gimbal mounted solid state recessed lighting

Description:
This patent application claims benefit under 35 U.S.C. 119(e), of the earlier filing date of U.S. Provisional Patent Application Ser. No. 61/934,989, filed Feb. 3, 2014. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention disclosed relates generally to lighting fixtures and in particular to heat dissipation in recessed lighting fixtures. 
     2. Discussion of the Related Art 
     Recessed lighting fixtures are designed to be minimally visible from below a ceiling in which they are mounted. LED light sources used for recessed lighting typically generate significant quantities of heat, requiring the use of a heat sink as part of the lighting fixture, to avoid overheating. The LED light source and an associated optic, are typically mounted in the heat sink so as to project light from the bottom of the heat sink. In some designs the heat sink may be supported in a mounting frame that is suspended by bar hangers fastened between joists above the ceiling. The mounting frame is positioned so that the bottom of the heat sink passes through an opening in the ceiling and is approximately flush with the bottom surface of the ceiling. A trim ring typically surrounds the opening in the ceiling, to mask the opening. 
     Directional LED recessed lighting fixtures are available, wherein a pivoted support or gimbal supports the heat sink and allows the rotation of the heat sink about a single axis. The directional or gimbal LED is typically capable of an adjustment range of from 0°-35° from vertical, for example. Conventionally, the heat sink containing the optic, is a rotatable inner heat sink that is pivotally mounted by gimbal supports within an outer heat sink. The inner heat sink is often the primary heat sink for the LED. Thus, it is an advantage to have the largest possible inner heat sink, to allow the LED to run at the coolest temperature possible. 
     An example directional or gimbal LED lighting fixture is described in U.S. Pat. No. 8,182,116, which depicts a heat sink that is pivotally mounted by gimbal supports within a much larger housing. The disclosed design does not enlarge the size of the heat sink to maximize its heat dissipation characteristics, since there is a large unused space shown within the housing. 
     Another example directional or gimbal LED lighting fixture is described in U.S. Pat. No. 8,403,533, which depicts an inner heat sink that is pivotally mounted by gimbal supports within an outer heat sink. The inner heat sink includes an arm that moves up into the outer heat sink for hinge tension and heat transfer. However the shape of the inner heat sink is not optimized to be as large as possible and yet still be capable of directional adjustment on its gimbal supports. 
     Accordingly, there is a need for a design of a rotatable inner heat sink for a directional or gimbal mounted LED recessed lighting fixture, which occupies a maximum available volume within an outer heat sink, and yet is still capable of directional adjustment on its gimbal supports. 
     SUMMARY OF THE INVENTION 
     Example embodiments of the invention provide an improved design of a rotatable inner heat sink for a directional or gimbal LED lighting fixture, which occupies a maximum available volume within an outer heat sink, and yet is capable of full directional adjustment on its gimbal supports. 
     In accordance with an example embodiment of the invention, a heat sink for a directional lighting fixture comprises a rotatable inner heat sink that is generally wedge-shaped with a narrow top portion and a broader bottom portion. The inner heat sink is configured to fit within a hollow interior of an outer heat sink that has a substantially vertical inside wall. The inner heat sink has an opening in the bottom portion for transmission of light from a light source housed within the inner heat sink. The bottom portion of the inner heat sink is configured to be exposed through an opening at a bottom of the outer heat sink, to enable further transmission of the light transmitted from the opening in the inner heat sink. 
     A gimbal shaft is configured to pivotally mount the rotatable inner heat sink to the inside wall of the outer heat sink. 
     The rotatable inner heat sink has a vertical surface formed on one side between the narrow top portion and the broader bottom portion. The vertical surface is close to the inside wall of the outer heat sink, when the inner heat sink is rotated in one direction on the gimbal shaft, to direct light in a first direction. 
     The rotatable inner heat sink has an offset surface that is offset by an acute angle from vertical and intersects the vertical surface. The offset surface is formed on an opposite side of the inner heat sink from the one side, between the narrow top portion and the broader bottom portion. The offset surface is close to the inside wall of the outer heat sink, when the inner heat sink is rotated in an opposite direction to the one direction on the gimbal shaft, to direct light in a second direction. 
     In this manner, the rotatable inner heat sink occupies a maximum available volume within the outer heat sink, and yet is still capable of directional adjustment on its gimbal supports. 
     Two example embodiments are described for the rotatable inner heat sink. In a first example embodiment, the vertical surface of the rotatable inner heat sink is planar and the offset surface of the rotatable inner heat sink is substantially planar and may include heat-dissipating ribs. In a second example embodiment, the vertical surface of the rotatable inner heat sink is cylindrical and the offset surface of the rotatable inner heat sink is substantially cylindrical and may include heat-dissipating ribs. 
     The rotatable inner heat sink may have an offset surface that is offset by an angle from vertical that ranges from 0 degrees to 35 degrees. 
     The light source housed within the rotatable inner heat sink may be an LED light source. 
     The bottom portion of the rotatable inner heat sink may have a diameter that is approximately the same as the opening at the bottom of the outer heat sink. 
    
    
     
       DESCRIPTION OF THE FIGURES 
         FIG. 1A  is a front perspective view from the right side, in partial cross section, of a heat sink for a directional lighting fixture with a rotatable inner heat sink that is generally wedge-shaped to fit within a hollow interior of an outer heat sink that has a substantially vertical inside wall. The rotatable inner heat sink is shown rotated in one direction to direct light in a first direction. The figure shows a first embodiment of the wedge-shaped rotatable inner heat sink comprised of a vertical surface that is planar and an offset surface that is substantially planar and includes heat-dissipating ribs. 
         FIG. 1B  is a front perspective view from the right side, in partial cross section, of the heat sink of  FIG. 1A , with the first embodiment of the wedge-shaped rotatable inner heat sink shown rotated in an opposite direction from that shown in  FIG. 1A , to direct light in a second direction. 
         FIG. 1C  is a top front perspective view from the right side, of the first embodiment of the wedge-shaped rotatable inner heat sink, showing a gimbal shaft configured to pivotally mount the rotatable inner heat sink to the inside wall of the outer heat sink. 
         FIGS. 2A to 2F  is a sequence of top front perspective views from the left side, of component geometric shapes that comprise a second embodiment of the wedge-shaped rotatable inner heat sink shown in  FIGS. 3A to 3C . The second embodiment of the wedge-shaped rotatable inner heat sink is comprised of a vertical surface that is cylindrical and an offset surface that is substantially cylindrical. 
         FIG. 3A  is a top front perspective view from the left side, of the second embodiment of the wedge-shaped rotatable inner heat sink, showing a vertical cylindrical surface on one side and an offset cylindrical surface on the opposite side that includes heat-dissipating ribs. 
         FIG. 3B  is a top front perspective view from the right side, of the second embodiment of the wedge-shaped rotatable inner heat sink, showing the offset cylindrical surface. 
         FIG. 3C  is a bottom back perspective view from the left side, of the second embodiment of the wedge-shaped rotatable inner heat sink, showing an opening in the bottom portion for transmission of light from a light source housed within the rotatable inner heat sink. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     Example embodiments of the invention provide an improved design of a rotatable inner heat sink for a directional or gimbal mounted LED recessed lighting fixture, which occupies a maximum available volume within an outer heat sink, and yet is capable of full directional adjustment on its gimbal supports. 
       FIG. 1A  is a front perspective view from the right side, in partial cross section, of a recessed fixture  50  for a directional lighting fixture. The trim frame  75  rests against the room side of the ceiling (not shown). The recessed fixture  50  includes a rotatable inner heat sink  110  that is generally wedge-shaped to fit within a hollow interior of an outer heat sink  130  that has a substantially vertical inside wall  132  that may be generally cylindrical. The wedge-shaped rotatable inner heat sink  110  is shown rotated in one direction to direct light in a first direction, generally shown as a vertical direction. The figure shows a first embodiment of the wedge-shaped rotatable inner heat sink comprised of a vertical surface  112  that is planar and an offset surface  114  that is substantially planar and includes heat-dissipating ribs. 
     The wedge-shaped rotatable inner heat sink  110  has a narrow top portion  121  and a broader bottom portion  118  and has an opening  120  in the bottom portion for transmission of light from a light source  125  housed within the rotatable inner heat sink  110 . The bottom portion  118  of the wedge-shaped rotatable inner heat sink  110  is configured to be exposed through an opening  122  at a bottom of the outer heat sink  130 , to enable further transmission of the light transmitted from the opening  120  in the rotatable inner heat sink  110 . 
     The first embodiment of the wedge-shaped rotatable inner heat sink  110  has the vertical flat or planar surface  112  formed on one side between the narrow top portion  121  and the broader bottom portion  118 . The vertical surface  112  is substantially parallel and close to the inside wall  132  of the outer heat sink  130 , when the rotatable inner heat sink  110  is rotated in one direction (shown in  FIG. 1A ) on a gimbal shaft  115  (shown in  FIG. 1C ), to direct light in a first direction, generally shown as a vertical direction in  FIG. 1A . The gimbal shaft  115  is configured to pivotally mount the rotatable inner heat sink  110  to the inside wall  132  of the outer heat sink  130 , to enable rotation of the rotatable inner heat sink  110  about the axis  116 . 
       FIG. 1B  is a front perspective view from the right side, in partial cross section, of the recessed fixture  50  of  FIG. 1A , with the rotatable inner heat sink  110  shown rotated in an opposite direction from that shown in  FIG. 1A , to direct light in a second direction, generally shown as directed at an acute angle offset from the vertical direction. The rotatable inner heat sink  110  has an offset surface  114  that is offset by an acute angle from vertical. The offset surface  114  of the rotatable inner heat sink  110  is substantially planar and may include heat-dissipating ribs. The offset surface  114  intersects the vertical surface  110  at the narrow top portion  121  of the rotatable inner heat sink  110 . The offset surface  114  is formed on an opposite side of the rotatable inner heat sink  110  from the vertical surface  112 , between the narrow top portion  121  and the broader bottom portion  118 . The offset surface  114  is substantially parallel and close to the inside wall  132  of the outer heat sink  130 , when the rotatable inner heat sink  110  is rotated on the gimbal shaft  115 , in an opposite direction (shown in  FIG. 1B ) to the direction shown in  FIG. 1A . Light is thereby directed in a second direction, generally shown as directed at an acute angle offset from the vertical direction, as shown in  FIG. 1B . 
     In this manner, the rotatable inner heat sink  110  occupies a maximum available volume within the outer heat sink  130 , and yet is still capable of directional adjustment about the axis  116 , on its gimbal supports  115 . 
     The rotatable inner heat sink  110  may have an offset surface  114  that is offset by an angle from vertical that ranges from 0 degrees to 35 degrees. 
     The light source  125  housed within the rotatable inner heat sink  110 , may be an LED light source. 
     The bottom portion  118  of the rotatable inner heat sink  110  may have a diameter that is approximately the same as the opening  122  at the bottom of the outer heat sink  130 . 
       FIG. 1C  is a top front perspective view from the right side, of the first embodiment of the wedge-shaped rotatable inner heat sink  110 , showing the gimbal shaft  115  configured to pivotally mount the rotatable inner heat sink  110  to the inside wall  132  of the outer heat sink  130 , for rotation about the axis  116 . Heat dissipating ribs are shown formed in the offset surface  114 . 
       FIGS. 2A to 2F  is a sequence of top front perspective views from the left side, of component geometric shapes that comprise a second embodiment of the wedge-shaped rotatable inner heat sink  110 ′ shown in  FIGS. 3A to 3C . The second embodiment of the wedge-shaped rotatable inner heat sink  110  is comprised of a vertical surface  112 ′ that is cylindrical and an offset surface  114 ′ that is substantially cylindrical. 
     The second embodiment of the wedge-shaped rotatable inner heat sink  110 ′ fits within the hollow interior of the outer heat sink  130  of  FIG. 1A , in the same manner as was described above for the first embodiment  110 . The second embodiment of the wedge-shaped rotatable inner heat sink  110 ′ includes the gimbal shaft  115  (shown in  FIG. 3A ) to pivotally mount the second embodiment of the rotatable inner heat sink  110 ′ to the inside wall  132  of the outer heat sink  130 . The gimbal shaft  115  enables rotation of the second embodiment of the rotatable inner heat sink  110 ′ about the axis  116 , in the same manner as was described above for the first embodiment  110 . 
       FIGS. 2A to 2F  is a sequence of top front perspective views from the left side, of the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′, showing component geometric shapes that comprise the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′. 
       FIG. 2A  is a top front perspective view from the left side, showing a cylinder forming a portion of the vertical cylindrical surface  112 ′ that comprises the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′. 
       FIG. 2B  is a top front perspective view from the left side, showing a spherical surface  113  that abuts a portion of the vertical cylindrical surface  112 ′ that comprise the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′. 
       FIG. 2C  is a top front perspective view from the left side, showing a cylinder forming a portion of the offset cylindrical surface  114 ′ abutting the spherical surface  113  that comprise the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′. 
       FIG. 2D  is a top front perspective view from the left side, showing a cylinder forming a portion of the offset cylindrical surface  114 ′ intersecting and passing through the vertical cylindrical surface  112 ′ that comprise the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′. 
       FIG. 2E  is a top front perspective view from the left side, showing a portion of the cylinder forming the offset cylindrical surface  114 ′, trimmed so that it does not pass through the vertical cylindrical surface  112 ′ that comprise the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′. 
       FIG. 2F  is a top front perspective view from the left side, showing the offset cylindrical surface  114 ′ and the vertical cylindrical surface  112 ′ that comprise the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′. 
       FIG. 3A  is a top front perspective view from the left side, of the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′, showing the vertical cylindrical surface  112 ′ on one side and the offset cylindrical surface  114 ′ on the opposite side. The gimbal shaft  115  is shown, to pivotally mount the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′to the inside wall  132  of the outer heat sink  130 , for rotation about the axis  116 . 
       FIG. 3B  is a top front perspective view from the right side, of the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′, showing the offset cylindrical surface  114 ′. Heat dissipating ribs are shown formed in the offset cylindrical surface  114 ′. The gimbal shaft  115  and axis  116  are shown. 
       FIG. 3C  is a bottom back perspective view from the left side, of the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′, showing the opening  120  in the bottom portion  118  for transmission of light from a light source housed within the second embodiment of the wedge-shaped rotatable inner heat sink  110 ′. The vertical cylindrical surface  112 ′, gimbal shaft  115  and axis  116  are shown. 
     The resulting embodiments of the wedge-shaped rotatable inner heat sink for a directional or gimbal mounted LED recessed lighting fixture, occupies a maximum available volume within the outer heat sink, and yet is still capable of directional adjustment on its gimbal supports.