Patent Publication Number: US-7581856-B2

Title: High power LED lighting assembly incorporated with a heat dissipation module with heat pipe

Description:
FIELD OF THE INVENTION 
   The present invention relates to a design for a light emitting diode (LED) lighting assembly, and in particular to a high power LED lighting assembly incorporated with a heat dissipation module using heat pipe that is capable of dissipating heat effectively from the LED lighting assembly. 
   BACKGROUND OF THE INVENTION 
   According to the conclusion of Kyoto Global Climate Conference, many countries have to cut their greenhouse gas emissions to below 6% to 1990 level in years between 2008 and 1012. With the power consumption for lighting purposes accounting for more than 20% of the livelihood-based energy, the development of energy saving lighting technology becomes even more important. 
   Light-emitting diode (LED), an optoelectronic semiconductor component that radiates by applying external voltage to simulate the electrons to produce lighting, provides the advantages of low power consumption and long service life, therefore prompting the worldwide researches and development of the related technologies. Practical applications currently are generally limited to low power indicator lamps, but with the active developments on high power LED technology in recent years. The illumination wattage is gradually improving, showing its potential for replacing conventional incandescent light bulb for lighting. Besides, the illumination efficiency of LED is soon expected to exceed 80 limens per watt, which is about six times the illumination efficiency of the conventional incandescent tungsten light bulb. In order to provide sufficient flux of light for lighting device, current designs include the assembly of arrayed LEDs with dozens of hundreds of LED lamps being packed together in wide range of applications from outdoor display to lighting. 
   However, with high power LED advancing, the heat generated by high power LED is also increased, and the dissipation of heat from LED becomes a critical problem. During operation, the illumination of LED lamps generates hot spots of high temperature in radiating area on high power LED, and currently, no solution is provided. This problem limits the development and applications of LED lamps. The poor heat dissipation of hot spots results to the overheating of LED lamps. When the junction temperature exceeds 120° C., the high temperature damages the LED lamps and leads to lower performance of LED, shorter service life, and even the peril of burnout. Hence, to promote the application of LED, the heat dissipation must be effectively settled. 
   Thus, it is desired to develop a LED device of high power and a means for effectively dissipate heat from a LED device for enhancing the performance, service lifespan, and reliability of lighting devices. 
   SUMMARY OF THE INVENTION 
   A primary object of the present invention is to provide a high power LED lighting assembly that comprises a plurality of arrays of LED for emitting light. The LED lighting assembly provides sufficient illumination with low power consumption, which can replace conventional incandescent light bulbs and florescent light sources. 
   Another object of the present invention is to provide a heat dissipation module for dissipating heat. The heat dissipation module comprises at least one heat pipe for conducting heat from the heated section of the heat pipe to the cooling region which is fitted to a heat dissipation module for dissipating the heat efficiently. 
   A further object of the present invention is to provide a heat dissipation module for incorporating to a LED light assembly. The heat dissipation module is capable to effectively remove heat from the LEDs to the outside, and maintain the LED light assembly at an appropriate operation temperature. The arrangement of the heat dissipation module eliminates the overheating at any spots of the heat dissipation module and maintains the lighting stability of heat dissipation module. 
   To fulfill the above objects, the present invention provides a high power LED lighting assembly incorporated with a heat dissipation module for incorporating to the LED light assembly. The LED lighting assembly comprises a heat exchange base, at least one LED array, at least one heat pipe and a heat dissipation module. The heat exchange base comprises at least one LED configuration plan for mounting of the LED array and at least a hollow part for insertion of the heat pipe. The LED array is arranged at a predetermined projecting angle at the LED configuration plane. The heat pipe comprises a heated section, a cooling section and a conducting section, and contains a working fluid. The heat exchange base is mounted to the heated section and the heat dissipation module is mounted to the cooling section. The thermal energy generated by the LEDs is conducted from the heat exchange base to the heated section of the heat pipe, whereby allowing the working fluid in the heat pipe to be heated and vaporized, and flows, from the conducting section to the cooling section for dissipation at the heat dissipation module. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiment thereof, with reference to the attached drawings, in which: 
       FIG. 1  is a schematic view of a first embodiment of a high power LED lighting assembly incorporated with a heat dissipation module constructed in accordance with the present invention; 
       FIG. 2  is a perspective side view showing the components of the LED lighting assembly of  FIG. 1 ; 
       FIG. 3  is a schematic view of the LED lighting assembly of  FIG. 1  after the removal of its lamp shade; 
       FIG. 4  is a partial exploded schematic view showing the arrangement of LED array of the LED lighting assembly of  FIG. 3 ; 
       FIG. 5  is an exploded schematic view of the LED lighting assembly of  FIG. 3 ; 
       FIG. 6  is a top plan view of a heat exchange base of the LED lighting assembly; 
       FIG. 7  is a schematic side view of the of the LED lighting assembly of  FIG. 3 ; 
       FIG. 8  is a cross-sectional view of the LED lighting assembly taken along line  8 - 8  of  FIG. 7 ; 
       FIG. 9  is a schematic view of a second embodiment of the high power LED lighting assembly incorporated with a heat dissipation module constructed in accordance with the present invention, after the removal of its lamp shade; 
       FIG. 10  is a partial exploded view of the high power LED lighting assembly of  FIG. 9 ; 
       FIG. 11  is a schematic side view of the high power LED lighting assembly of  FIG. 9 ; and 
       FIG. 12  is a cross-sectional view of the LED lighting assembly taken along line  12 - 12  of  FIG. 11 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to the drawings and in particular to  FIGS. 1 to 3 , a first embodiment of a high power LED lighting assembly incorporated with heat dissipation module constructed in accordance with the present invention, generally designated with reference numeral  100 , is shown. The high power LED lighting assembly  100  of the present invention comprises a heat exchange base  1 , a plurality of LED arrays  2 , a heat pipe  3 , a heat dissipation module  4 , and a lamp shade  5 . The lamp shade  5  covers the heat exchange base  1 , the LED arrays  2 , the heat pipe  3  and the heat dissipation module  4 , and is removable for maintenance of the components. The heat exchange base  1  is arranged at the lower part of the LED lighting assembly  100  and the heat dissipation module  4  is arranged at the upper part of the LED lighting assembly  100 . 
   Please refer to  FIGS. 4 to 8 .  FIGS. 4 and 5  shows the exploded schematic views of the high power LED lighting assembly after the removal of the lamp shade.  FIG. 6  is a top plan view of the heat exchange base of the LED lighting assembly.  FIGS. 8 and 9  show a side view of the of the LED lighting assembly. As shown, the heat exchange base  1  is of approximately cubic shape comprising a plurality of LED configuration planes  11 , a central hollow part  12 , a plurality of thermal stress pressing structure  14  and an internal surface  15 . 
   The LED configuration plane  11  is located on the outer surface of the heat exchange base  1 . The hollow part  12  is arranged at the central part of the heat exchange base  1  with a top opening and a bottom opening, defining a space. The thermal stress pressing structure  14  comprises a through hole  141  and a channel  142  connecting to the through hole  141 . The channels  142  communicate with the central hollow part  12 . Electric wires for supplying power to the LEDs are arranged at the channel  142  of the thermal stress pressing structure  14 . 
   Each of the LED configuration planes  11  is provided with a LED array  2 . The LED array  2  comprises a plurality of LEDs  21  arranged in a predetermined pattern and a circuit board  22 . The circuit board  22  is perforated with an aperture  221 , in where the LEDs  21  are fitted to, such that the bottoms of LEDs and the bottom of the circuit board form a continuous flat surface for close contact between the LEDs and the LED configuration plane  11  of the hear exchange  1 . The LED configuration planes  11  are coated with a layer of thermal conductive medium for leveling up the junctions among the LEDs and between the LEDs and the LED configuration planes  11 , reducing the thermal resistance between the components. The heat exchange base  1  is made of heat sink material that allows rapid absorption, conduction, and dissipation of the thermal energy generated by the LEDs  21 . In addition, the LED array  2  is replaceable, allowing the replacement of high watt and high power LEDs of different models. 
   The heat pipe  3  comprises a heated section  31 , a cooling section  32 , and a conducting section  33  that connects the heated section  31  to the cooling section  32 . The heat pipe  3  contains a working fluid and is regularly cylindrical in shape. The heated section  31  is inserted into the central hollow part  12  of the heat exchange base  1 , while the conducting section  33  extends outward from the top opening of the heat exchange base  1 . The cooling section  32  of the heat pipe  3  is inserted to the central hollow part of the heat dissipation module  4 . 
   During operation of the LED lighting assembly  100 , the temperature of the heat exchange base  1  and the heat pipe  3  gradually increases. The raise in temperature causes the heat exchange base  1  and the heat pipe  3  to expand. As the heat exchange base  1  and the heat pipe  3  have different expansions, it generates a thermal stress at the interface between the internal surface  15  of the heat exchange base  1  and outer surface of the heat pipe  3 , which enhances the contact between the internal surface  15  of the heat exchange base  1  and the heat pipe  3 . The thermal stress increases as the temperature increases. The thermal stress acting on the thermal stress pressing structure  14  of the heat exchange base  1  makes the heat exchange base  1  clamp to the heat pipe  3 , thus lowers the thermal resistance between the heat exchange base  1  and the heat pipe  3  and enhances the conduction of the thermal energy therebetween. 
   When the LEDs  21  of the LED array  2  are electrically powered and illuminates, the thermal energy generated is conducted through the heat exchange base  1  to the heated section  31  of the heat pipe  3 . The working fluid of the heated section  31  is heated and vaporized. A pressure difference is generated between the vapor at the cooling section  32  and the working liquid at the heated section  31 . The pressure difference promotes the vapor to flow from the conducting section to the cooling section  32  and assists the heat removal therefrom. 
   The vapor flowed to the cooling section  32  of the heat pipe  3  carries heat which is transmitted to and absorbed by the heat dissipation module  4  mounted to the cooling section  32 . The heat dissipation module  4  comprises a plurality of fins extended radially from the hollow part of the heat dissipation module  4 . The fins provide large surface areas for dissipation of heat. Thereby, the heat dissipation module  4  absorbs the thermal energy carried by the vaporized working fluid and dissipates the heat through the fins. Therefore, the heated and vaporized working fluid is cooled and condenses into liquid form. By means of the structure of the heat pipe  3 , the condensed working fluid flows back by capillary action to the heated section  31 . Through the vaporization and condensation of the working fluid, the thermal energy is repeatedly and rapidly dissipated to the outside. 
   The lamp shade  5  covers the heat exchange base  1 , the LED arrays  2 , the heat pipe  3 , and the heat dissipation module  4 . The lamp shade  5  comprises a plurality of longitudinal heat dissipating vents  51  located in the vicinity of the heat dissipation module  4  to allow the heated air surrounding the heat dissipation module  4  to exchange by convection. 
   The lamp shade  5  is connected to the heat dissipation module  4 . The connection between the lamp shade  5  and the heat dissipation module  4  is coated with a thermal conductive material which may be viscous liquid, adhesive pads allowing direct adhesion, solidifiable material or other medium that facilitates the conduction of the thermal energy. In addition, the lamp shade  5  may be kept at a predetermined distance from the heat dissipation module  4  and provided with a fan additionally to enhance convection and heat transfer. Also, the external surface of the lamp shade  5  may be coated, adhered, or bonded with a layer of high radiation substance, for radiating the heat therefrom. 
   Furthermore, the heat exchange base  1  comprises a plurality of lighting auxiliary structures  13  which protrudes outwards from the two sides of the LED configuration plane  11  to a predetermined length. The light source auxiliary structures  13  assist focusing or diverging the light source generated by the LEDs  21  of the LED array  2 . In the embodiments illustrated, the bottoms of the LEDs  21  are adhered flat to the LED configuration planes  11 , while the LED configuration planes  11  are parallel to the heat pipe  3 . The light produced by the LEDs  21  is projected perpendicular to the heat pipe  3  to the surroundings. Alternatively, by means of bending the brackets of the LEDs  21 , or by slantly inserting the circuit boards  22  into the LED configuration planes  11 , the LEDs  21  can be arranged at a specified angle on the LED configuration planes  11  of the heat exchange base  1 , to allow the light generated by the LEDs  21  to project towards areas slantly above or below the exchange base  1  in every direction. The number of LED arrays  2  used may be varied according to brightness requirement. It is understandable that a single array with a sufficient number of LEDs may be used. 
     FIG. 9  is a schematic view of a second embodiment of the high power LED lighting assembly incorporated with a heat dissipation module constructed in accordance with the present invention, after the removal of its lamp shade.  FIG. 10  is a partial exploded view of the high power LED lighting assembly of  FIG. 9 .  FIGS. 11 and 12  show the side views of the LED lighting assembly of  FIG. 9 . 
   The second embodiment is different from the first embodiment in that the heat exchange base  1  comprising a plurality of peripheral hollow parts  12  arranged at selected location of the heat exchange base  1 , while running through the top and bottom of the said heat exchange base  1 . Each of the peripheral hollow parts  12  is inserted with a heat pipe  3 . That is, the peripheral heat pipes  3  are arranged circularly around the central hollow part  12  of the heat exchange base  1 , and each peripheral hollow part  12  is adjacent to one of the LED configuration planes  11 , allowing the thermal energy generated by the LEDs  21  of the LED array  2  to be conducted through the heat exchange base  1  to the heated section  31  of the heat pipe  3 . 
   The present invention has been described with reference to the preferred embodiment of this present invention that provides a high power LED lighting assembly that is incorporated with heat dissipation module, wherein the shape of the heat pipe  3  can be tubular, rectangular, or that of a slab or other varieties. The dimension of the heat pipe may be varied according to requirements, and is made of heat conductive material. The heat dissipation module may be of any specified form and shape, e.g. cross-typed, cylindrical, fin-typed, etc., and may be made by aluminum extrusion, die casting, mold injection or mechanical machining. 
   The heat pipe and fins are simple in structure, easy for installation and cheap for manufacturing. This allows the structure of the present invention can be varied and the application of the present invention is broad. The heat dissipation module can be applied in different fields and incorporated to many devices, such as indoor lighting, street lamps, and high power LED device 
   While the invention has been described in connection with what is presently considered to the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangement included within the spirit and scope of the appended claims.