Patent Publication Number: US-7896528-B2

Title: LED lamp

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an LED lamp, more particularly to an LED lamp having a heat sink enclosed in an envelope for dissipating heat generated by LEDs of the LED lamp. 
     2. Description of Related Art 
     The high power LED light devices produce considerable amount of heat, which may cause performance degrade or even damage if the heat is not removed from the LED chips efficiently. In an LED light device, the core is an LED chip mounted on a substrate. A transparent top covering the LED chip serves as a lens for modifying the direction of the emitted light. Although there are many different designs, the major heat dissipation route for the heat produced by the LED chip usually is managed through the base to which the LED chip is mounted or through an additional metal heat sink below the base and then to an outer heat sink. 
     Traditional adoption of the fans for active cooling system not only introduces noise problems but also brings risk of damage to an LED lamp if the fan is out of order. In contrast, passive cooling with natural convection is quite, continuous and time-unlimited. But since a natural convection system is relative weak for heat dissipation, to solve this problem, a large surface area is needed to enhance heat dissipation capacity. Most passive cooling devices for LED lamps adopt highly heat-conductive materials, such as copper or aluminum, with extended surfaces for heat dissipation. However, to facilitate flowage of airflow through the fins, fins of the heat sink of the LED lamp are commonly exposed to outside of the housing; this makes the fins in a risk of being broken and hurting users of the LED lamp. Furthermore, dust or rainwater on the fins may creep along the heat sink to cause the LEDs to have a contamination by the dust or a short circuit by the rainwater. 
     What is needed therefore is a LED lamp having an improved structure which overcomes above mentioned disadvantages. 
     SUMMARY OF THE INVENTION 
     An LED lamp includes a housing, a bracket snugly received in the housing, a connecting member fixed to a top of the bracket, a heat sink standing on a top of the connecting member, a plurality of LEDs attached an outer surface of the heat sink and an envelope which is placed on the top of the connecting member, encloses the heat sink and the LEDs therein and engages with the housing. Heat generated by the LEDs is absorbed by a spreader of the heat sink and then delivered to fins of the heat sink to be dissipated into air surrounding the heat sink and enclosed by the envelope. The heat sink is totally encapsulated by the envelope; thus, the fins of the heat sink are prevented from being exposed outwardly. Thus, a danger of break of the fins and possibility that the fins may hurt a user of the LED lamp is avoided. In addition, the LEDs can be sufficiently protected by the envelope from attack of dust and rainwater. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present LED lamp can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present LED lamp. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is an isometric, assembled view of an LED lamp in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is an exploded view of  FIG. 1 ; 
         FIG. 3  is an exploded view of the LED lamp of  FIG. 1  from another aspect; and 
         FIG. 4  is a partially assembled view of the LED lamp of  FIG. 2  from another aspect. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-3 , an LED lamp in according with a preferred embodiment is illustrated. The LED lamp is configured to provide an even illumination in home or in a garden. The LED lamp comprises a housing  10 , a bracket  20  snugly inserted into the housing  10 , a connecting member  30  coupled to a top of the bracket  20 , a heat sink  40  fixed to a top of the connecting member  30 , a plurality of light-emitting components (not labeled) mounted on a lateral side and a top of the heat sink  40 , and a transparent/translucent envelope  50  mounted over the connecting member  30  and covering the heat sink  40 . 
     The housing  10  comprises a box-shaped main body  12 , an extension portion  14  extending upwardly from the main body  12 , a covering panel  16  fixed to a front side of the main body  12  by screws (not shown) and a base panel  18  on which the main body  12  is mounted. The main body  12  comprises two parallel side panels  122  and a rectangular rear panel  124  perpendicularly interconnecting rear sides of the two opposite side panels  122 . The side panels  122  respectively have two fixing flanged  1220  extending perpendicularly and inwardly toward each other from front sides thereof. Either of the fixing flanges  1220  defines a plurality of through orifices  1222  therein for receiving screws which extend through the covering panel  16 . The extension portion  14  is formed by prolonging one of the side panels  122  upwardly and vertically. Two holding flanges  142  extend inwardly and perpendicularly from two opposite sides of the extension portion  14 . The holding flanges  142  are provided for clipping the envelope  50  therebetween, and define therein a plurality of strip-shaped vents  1420  parallel to each other and a plurality of piercing orifices  1422  located adjacent to vertical edges of the holding flanges  142 . The vents  1420  are provided for decorative purpose. 
     The covering panel  16  has a size substantially equal to that of the rear panel  124  and is provided to be connected to the two fixing flanges  1220  of the main body  12  to thereby cover an opening (not labeled) between the fixing flanges  1220 . The rear panel  124  defines a plurality of through orifices  162  adjacent to two lateral edges thereof. The through orifices  162  are respectively in alignment with the corresponding through orifices  1222  of the fixing flanges  1220  for extension of the screws therein. 
     The base panel  18  is rectangular and provided for supporting the main body  12  thereon. The base panel  18  in a centre thereof defines a through hole  180  for an upward extension of lead wires (not shown) therethrough. The lead wires are used for electrically connecting the LED lamp to a power source. The base panel  18  has four retaining protrusions  182  extending upwardly from a top surface thereof. The retaining protrusions  182  are respectively located near four corners of the base panel  18  and each define a locking orifice  1820  extending through two opposite sides thereof. 
     The bracket  20  is integrally made of a highly heat-conductive material such as aluminum or copper, and has a configuration in complementary with an inner spaced of the main body  12  for being snugly inserted into the main body  12  of the housing  10 . The bracket  20  has two lateral side plates  22  and a connecting plate  24  interconnecting the two side plates  22 . The two side plates  22  are perpendicular to the connecting plate  24  and each has two mounting flanges  220  bent perpendicularly and inwardly from two opposite sides thereof. Each of the mounting flanges  220  defines therein a plurality of engaging orifices  222  arranged along a vertical direction for threadedly receiving the screws extending through the through orifices  162 ,  1222  of the covering panel  16  and the main body  12  in sequence, thereby securing the covering panel  16  and the flanges  1220  to the bracket  20 . Each of the mounting flanges  220  defines therein two fixing holes  224  which are located respectively adjacent to upper and lower ends thereof for fixing the connecting member  30  and the base panel  18  respectively to upper and lower ends of the bracket  20 . The connecting plate  24  is closer to the rear ones of the mounting flanges  220  than the front ones, in order to form an accommodating room for receiving related electronic components  200  therein. The related electronic components  200  are mounted on a front side of the connecting plate  24 . The connecting plate  24  has a plurality of vertical protruding fins  242  arranged on a rear side thereof, for removing heat generated by the related electronic components  200 . 
     The connecting member  30  is integrally made of a highly heat-conductive material such as aluminum or copper, and configured to support and hold the heat sink  40  and the envelope  50  thereon. The connecting member  30  is rectangular and in a centre thereof defines a through hole  32  for an upward extension of the lead wires therethrough. The connecting member  30  has an engaging flange  34  extending upwardly and perpendicularly from a periphery thereof for engaging with the envelope  50  and holding the heat sink  40  in position. The connecting member  30  has four retaining protrusions  36  extending downwardly from a bottom surface thereof. The retaining protrusions  36  are respectively located near four corners of the connecting member  30 . Each retaining protrusion  36  defines a locking orifice  360  extending through two opposite sides thereof for engagingly receiving a screw extending through a corresponding upper fixing hole  224  of the bracket  20  to securely couple the connecting member  30  to the top of the bracket  20 . 
     The heat sink  40  is integrally made of a highly heat-conductive material such as aluminum or copper, and comprises a spreader  42  and a plurality of fins  44  extending outwardly from the spreader  42 . The spreader  42  comprises a vertical plate  420  and two horizontal plates  422  extending outwardly and perpendicularly from two opposite top and bottom ends of the vertical plate  420 . The fins  44  extend horizontally from a lateral side of the vertical plate  420 , are perpendicular to the vertical plate  420  and located between the two horizontal plates  422 . 
     The envelope  50  is made of transparent/translucent plastic or glass and in the form of a cuboid box and configured to be placed on the connecting member  30  and enclose the heat sink  40  therein. The envelope  50  has an opening (not labeled) at a bottom end thereof for snugly receiving the engaging flanges  34  of the connecting member  30  therein and a receiving recession  52  at a corner thereof for accommodating the extension portion  14  of the housing  10 . The envelope  50  defines a plurality of retaining orifices  520  in the receiving recession  52  thereof and located adjacent to a brink of the receiving recession  52  for engagingly receiving screws (not shown) which extend through the piercing orifices  1422  of the extension portion  14  of the housing  10  to couple the envelope  50  with the housing  10 . 
     Also referring to  FIG. 4 , in assembly of the LED lamp, the bracket  20  is placed on the base panel  18  of the housing  10  and coupled to the base panel  18  by screws extending through the lower fixing holes  224  of the bracket  20  to engage into the locking orifices  1820  of the retaining protrusions  182  of the base panel  18 . The connecting member  30  is secured on the top of the bracket  20  by screws extending through the upper fixing holes  224  of the bracket  20  to screw into the locking orifices  360  of the retaining protrusions  36  of the connecting member  30 . The bracket  20  assembled with the base panel  18  and the connecting member  30  is then upwardly inserted into the main body  12  of the housing  10 . The screws extend through the through orifices  162 ,  1220  of the covering panel  16  and the main body  12  to screw into the engaging orifices  222  of the bracket  20 , to thereby securely connect the bracket  20 , the main body  12  of the housing  10  and the covering panel  16  together. The lower horizontal plate  422  of the heat sink  40  is disposed on the connecting member  30  and closely surrounded by the engaging flange  34 . The heat sink  40  can be fixed to the top of the connecting member  30  by soldering and adhering. The LEDs  100  are attached to outer surfaces of the vertical plate  420  and the upper horizontal plate  422  of the heat sink  40 . The envelope  50  is placed on the connecting member  30 , receives the engaging flange  34  of the connecting member  30  in the opening thereof and receives the extension portion  14  of the housing  10  in the receiving recession  52  thereof. The envelope  50  encloses the heat sink  40  to which the LEDs  100  are mounted therein and is coupled with the housing  10  by the screws extending through the piercing orifices  1422  of the extension portion  14  to screw into the retaining orifices  520  of the envelope  50 . After assembly, the decorative vents  1420  are located corresponding to the fins  44 . 
     In use of the LED lamp, heat generated by the LEDs  100  is absorbed by the spreader  42  of the heat sink  40  and then delivered to the fins  44  to be dissipated into surrounding air of the heat sink  40 . The heat sink  40  is totally encapsulated by the envelope  50 , thus avoiding rainwater or dust from reaching the heat sink  40  to cause the LED  100  to have a short circuit by the rainwater or a contamination by the dust. In addition, since the fins  44  are totally enclosed by the envelope  50 , the fins  44  are protected from break. Also, it is not possible for the fins  44  to hurt a user of the LED lamp. 
     It is believed that the present invention and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.