Abstract:
A heat-dissipating downlight lamp holder has a lamp holding unit, multiple fins and a bottom board. The fins are mounted on a periphery of the lamp holding unit to effectively dissipate heat of a light bulb mounted in the lamp holding unit out of the lamp holder. The bottom board located underneath the lamp holding unit has multiple air inlets formed through the bottom board to let cold air under the lamp holder enter the lamp holding unit through the air inlets. By convection, heat dissipated from the fins is carried away from the downlight, thereby effectively reducing heat accumulated by the light bulb and preventing the light bulb from being damaged by high heat.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a lamp holder, and more particularly to a downlight lamp holder used for a light-emitting diode (LED) bulb and effectively dissipating heat generated by the LED bulb. 
         [0003]    2. Description of the Related Art 
         [0004]    Lighting is one of the great achievements in human history. Lighting enables human beings to conveniently move and work at night. Since the advent of the first light bulb, lighting devices have migrated from conventional incandescent light bulbs and fluorescent lamps to light-emitting diodes (LED) with high luminance and low power consumption. 
         [0005]    Despite the mentioned advantages, LED has been found disadvantageous in generating high heat. If the temperature of LED is not controlled properly, the life cycle of LED will be significantly shortened. Although the implementation of LED with low heat generation is technically feasible, the cost of such current technical solutions is still high. On the other hand, conventional heat-dissipating devices are usually mounted outside the lamp holders, for example on the lamp holders. The heat-dissipating devices mounted on the lamp holders not only have an unsatisfactory cooling effect but also increase the overall size of the lamp holders. Based on the issues of the conventional lamp holders, the conventional lamp holders need to be further improved. 
       SUMMARY OF THE INVENTION 
       [0006]    An objective of the present invention is to provide a downlight lamp holder used for LED bulbs and effectively dissipating heat generated by an LED bulb mounted inside the lamp holder. 
         [0007]    To achieve the foregoing objective, the heat-dissipating downlight lamp holder has a bottom board, a lamp holding unit and a heat-dissipating unit. 
         [0008]    The bottom board has a light exit hole and multiple air inlets. The light exit hole is centrally formed through the bottom board. The air inlets are formed through the bottom board and around the light exit hole. 
         [0009]    The lamp holding unit is mounted on the bottom board and has an inner tube, an inner top cover and an outer top cover. The inner tube is tubular, is securely mounted on the bottom board, and has two openings, a top edge and a bottom edge. The openings are respectively formed through a top and a bottom of the inner tube. The top edge is formed around the opening in the top of the inner tube. The bottom edge is formed around the opening in the bottom of the inner tube. The bottom edge of the inner tube is mounted between the light exit hole and the air inlets. The inner top cover is mounted on the top edge of the inner tube and has a top. The outer top cover is mounted on the top edge of the inner top cover. 
         [0010]    The heat-dissipating unit is mounted on the inner top cover and has multiple side fins securely mounted around a periphery of the inner tube. 
         [0011]    The heat-dissipating downlight lamp holder is advantageous in that the side fins are mounted on a periphery of the lamp holding unit to effectively dissipate heat of a light bulb mounted in the lamp holding unit out of the lamp holder. The bottom board has multiple air inlets formed therethrough to let cold air under the lamp holder enter the lamp holding unit through the air inlets. Heat dissipated from the side fins is carried away from the downlight by convection, thereby effectively reducing heat accumulated by the light bulb and preventing the light bulb from being damaged by excessively accumulated heat. 
         [0012]    Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a first embodiment of a heat-dissipating downlight lamp holder in accordance with the present invention; 
           [0014]      FIG. 2  is another perspective view of the heat-dissipating downlight lamp holder in  FIG. 1 ; 
           [0015]      FIG. 3  is an exploded perspective view of the heat-dissipating downlight lamp holder in  FIG. 1 ; 
           [0016]      FIG. 4  is a top view of an alternative embodiment of a heat-dissipating unit with heat conduction tubes for the heat-dissipating downlight lamp holder in  FIG. 1 ; 
           [0017]      FIG. 5  is a side view of the heat-dissipating downlight lamp holder in  FIG. 1  mounted on a ceiling; 
           [0018]      FIG. 6  is an operational side view in partial section of the heat-dissipating downlight lamp holder in  FIG. 1 ; 
           [0019]      FIG. 7  is an exploded perspective view of a second embodiment of a heat-dissipating downlight lamp holder in accordance with the present invention; and 
           [0020]      FIG. 8  is an operational side view in partial section of the heat-dissipating downlight lamp holder in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    With reference to  FIGS. 1 to 3 , a first embodiment of a heat-dissipating downlight lamp holder in accordance with the present invention has a bottom board  10 , a lamp holding unit  20  and a heat-dissipating unit  30 . 
         [0022]    The bottom board  10  is annular and has a light exit hole  101  and multiple air inlets  102 . The light exit hole  101  is centrally formed through the bottom board  10 . The air inlets  102  are formed through the bottom board  10  and around the light exit hole  101 . In the present embodiment, the bottom board  10  further has two lower fixing elements  11  securely mounted on the bottom board  10 . 
         [0023]    The lamp holding unit  20  is mounted on the bottom board  10 , and has an inner tube  21 , an inner top cover  22  and an outer top cover  25 . The inner tube  21  is tubular and has two openings, a top edge and a bottom edge. The openings are formed respectively through a top and a bottom of the inner tube  21 . The top edge is formed around the opening in the top, and the bottom edge is formed around the opening in the bottom. The bottom board  10  is securely mounted on the bottom edge of the inner tube  21 , and the bottom edge of the inner tube  21  is mounted between the light exit hole  101  and the air inlets  102 . In the present embodiment, the perimeter of the opening in the bottom of the inner tube  21  coincides with the perimeter of the light exit hole  101 . The inner top cover  22  is disc-shaped in cross section and mounted on the top edge of the inner tube  21 . The outer top cover  25  is mounted on a top of the inner top cover  22 . In the present embodiment, the lamp holding unit  20  further has a lampshade  23  securely mounted on a bottom of the inner top cover  22  and mounted in the inner tube  21 . The outer top cover  25  has multiple air outlets  251  formed through a top of the outer top cover  25 . 
         [0024]    The heat-dissipating unit  30  has multiple side fins  31 , multiple top fins  32  and multiple heat conduction tubes  33 . The side fins  31  are securely mounted around a periphery of the inner tube  21 . In the present embodiment, the side fins  31  are integrally formed around the periphery of the inner tube  21 . The top fins  32  are securely mounted on the top of the inner top cover  22 . The top fins  32  may be integrally formed on the top of the inner top cover  22 . The heat conduction tubes  33  are securely mounted on the top of the inner top cover  22 , and extend to the periphery of the inner tube  21 . Each heat conduction tube  33  is mounted between adjacent two of the top fins  32  on the inner top cover  22 , and an end of each heat conduction tube  33  is mounted between adjacent two of the side fins  31 . In the present embodiment, each heat conduction tube  33  has two integrally formed L-shaped bars. Each L-shaped bar has two segments. One segment of one L-shaped bar intersects with one segment of the other L-shaped bar in a V-shaped form. The other two segments of the two L-shaped bars are parallel. With reference to  FIG. 4 , an alternative example of the heat conduction tubes  33 A is shown. The segments of the heat conduction tubes  33 A mounted on the top of the inner top cover  22  are radially spaced apart from each other. 
         [0025]    With reference to  FIGS. 1 to 3  and  5 , the downlight lamp holder in accordance with the present invention can be combined with an electronic component set  40  and an LED bulb  60  to form a downlight. The downlight can be mounted in a ceiling  70 . The electronic component set  40  is mounted on the lamp holding unit  20 , and has multiple circuit board supports  41 , a circuit board  42  and a base  43 . One end of each circuit board support  41  is securely mounted on the top of the inner top cover  22 . The other end of each circuit board support  41  is securely mounted on a bottom of the circuit board  42 . The base  43  is securely mounted on the top of the outer top cover  25  and is electrically connected with the circuit board  42 . The LED bulb  60  is securely mounted on an inner side of the lampshade  23  and is electrically connected with the circuit board  42 . The downlight lamp holder is fixed on the ceiling through the lower fixing elements  11 . A power supply is connected with the base  43  to supply an operating power to the circuit board  42  and the LED bulb  60 . 
         [0026]    With reference to  FIGS. 3 and 6 , when the downlight is operated, heat radiated from the LED bulb  60  is dissipated through the following three paths. The first path is that heat is transferred to the top fins  32  through the inner top cover  22 . The second path is that heat is transferred to the heat conduction tubes  33  through the inner top cover  22 , is then transferred to the periphery of the inner tube  21 , and is further transferred to the side fins  31 . The third path is that heat is transferred to the side fins  31  through the inner tube  21 . Cold air enters the lamp holding unit  20  from the air inlets  102  of the bottom board  10 , and sequentially carries away heat from the side fins  31  and the top fins  32  by convection and dissipates heat to the ceiling  70  through the air outlets  251  of the outer top cover  25 , thereby effectively preventing heat from accumulating in the lamp holder. 
         [0027]    With reference to  FIGS. 7 and 8 , a second embodiment of a downlight lamp holder in accordance with the present invention is similar to the first embodiment except that the second embodiment further has an outer tube  24 B, multiple upper fixing elements  26 B and a fan assembly  50 B. The outer tube  24 B is tubular, is securely mounted on the bottom board  10 B, and has two openings, a top edge and a bottom edge. The openings are formed respectively through a top and a bottom of the outer tube  24 B. The top edge is formed around the opening in the top, and the bottom edge is formed around the opening in the bottom. The outer tube  24 B is mounted around the inner tube  21 B. The bottom edge of the outer tube  24 B surrounds the air inlets  102 B. The outer top cover  25 B is securely mounted on the top edge of the outer tube  24 B. The upper fixing elements  26 B are securely mounted on a periphery of the outer tube  24 B. The fan assembly  50 B is mounted between the inner top cover  22 B and the outer top cover  25 B, and has a fan tray  51  B and a fan  52 B. The fan tray  51  B is securely mounted on the top of the inner top cover  22 B. The fan  52 B is securely mounted on the fan tray  51 B and is electrically connected with the circuit board  42 B of the electronic component set  40 B. 
         [0028]    When the downlight lamp holder is in use, the outer tube  24 B surrounds the inner tube  21 B and the inner top cover  22 B to form an additional air flow passage for concentrating air flow. As the inner top cover  22 B has some assembling holes unused when being assembled with the fan assembly  50 B and there are slits formed through the top of the inner top cover  22 B, the air blown out by the fan assembly  50 B can enter the air flow passage formed between the inner top cover  22 B and the inner tube  21 B. The air flow circulation speed in the air flow passage is accelerated by operating the fan  52 B. When the fan assembly is operating, cooling air enters from the air inlets  102 B and is circulated through the air flow passage to sequentially carry away heat from the side fins  31 B and the top fins  32 B by convection, and the heated air is further blown out of the downlight lamp holder through the light exit hole  101 B, thereby lowering heat accumulated inside the downlight lamp holder. Additionally, by using the upper fixing elements  26 B, the downlight lamp holder can be more firmly mounted in a ceiling. 
         [0029]    Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.