LED lamp having a sealed structure

[0001] 1. Field of the Invention

[0002] The present invention relates to an LED lamp, and more particularly to an improved LED lamp having a sealed structure to prevent an entry of mist, dust, rainwater and other foreign matter into the LED lamp.

[0003] 2. Description of Related Art

[0004] An LED lamp is a type of solid-state lighting that utilizes light-emitting diodes (LEDs) as a source of illumination. An LED is a device for transferring electricity to light by using a theory that, if a current is made to flow in a forward direction through a junction region comprising two different semiconductors, electrons and holes are coupled at the junction region to generate a light beam. The LED has an advantage that it is resistant to shock, and has an almost eternal lifetime under a specific condition; thus, the LED lamp is intended to be a cost-effective yet high quality replacement for incandescent and fluorescent lamps.

[0005] When the LED lamp is used in the outdoors for illumination, mist, dust, rainwater or other foreign matter is prone to creep into the LED lamp, which may cause electric leakage or short circuit of the LED lamp, or a contamination of the LEDs used in the LED lamp.

[0006] What is needed, therefore, is an improved LED lamp which has a simple and novel structure, whereby the LED lamp is suitable to mass-manufacture and has an improved waterproof configuration for preventing rainwater, dust, etc. from creeping into the LED lamp.

[0007] An LED lamp includes a lamp holder, a heat sink, a plurality of LED modules, a cover, an envelope and a sealing cushion. The lamp holder has a connecting portion at a bottom thereof adapted for engaging with supporting rod to fix the LED lamp in position. The heat sink is disposed on the lamp holder. The LED modules are attached to a circumference of the heat sink. The cover is coupled to a top of the heat sink and thermally connects therewith so heat of the heat sink can be dissipated to surrounding air of the LED lamp through the cover. The envelope encloses the heat sink and the LED modules therein and has a lower end engaging with the lamp holder and an upper end engaging with the cover. The sealing cushion is provided in at least one of the combinations of the lamp holder and the envelope, and of the cover and the envelope to prevent an entry of foreign matter into the LED lamp.

[0008] Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which:

[0015] Referring to FIGS. 1-3, an LED lamp in accordance with a preferred embodiment is illustrated. The LED lamp comprises a lamp holder 10, a heat sink 20 mounted on the lamp holder 10, a plurality of LED modules 30 attached to the heat sink 20, a cover 40 covered on a top of the heat sink 20, and an envelope 50 located between the lamp holder 10 and the cover 40 and enclosing the heat sink 20 and the LED modules 30 therein. Three connecting shafts 200 are mounted around the envelope 50 and stand between the lamp holder 10 and the cover 40. The LED lamp is further provided with a first annular cushion 100 sandwiched between the envelope 50 and the lamp holder 10, and a second annular cushion 102 sandwiched between the envelope 50 and the cover 40 to prevent an entry of foreign matter such as mist, dust and rainwater from entering the LED lamp to cause the LED lamp to have an electric leakage or short circuit or to cause the LED modules 30 to be contaminated.

[0016] As expressly shown in FIG. 4, the lamp holder 10 comprises a discal base 12 and a connecting portion 14 extends downwardly from a central portion of a bottom of the base 12 for securing the LED lamp onto a supporting structure (not shown) such as a supporting rod. The base 12 has a bowl-shaped receiving chamber 120 downwardly recessing from a central portion thereof, for receiving a driving circuit module 300 therein. A through bore 121 is defined in a centre of a bottom of the receiving chamber 120 for an extension of lead wires into the LED lamp. The base 10 has an annular inner flange 122 extending upwardly from the top thereof and surrounding the receiving chamber 120 and an annular outer flange 124 concentric with the inner flange 122 and protruding upwardly from a top thereof. The inner flange 122 is preferred to have a height larger than that of the outer flange 124. The inner and outer flanges 122, 124 are spaced from each other, thereby defining a first groove 126 therebetween for receiving a bottom end of the envelope 50. Three cutouts 1240 are equidistantly defined in the outer flange 122 for facilitating an outflow of rainwater accidentally infiltrated into the first groove 126. Three first securing holes 128 are evenly defined in the base 12 and surround the outer flange 124, for respectively receiving three lower ends of the connecting shafts 200.

[0017] As shown in FIG. 5, the heat sink 20 is integrally made of a metal with a good heat conductivity, such as aluminum, copper or an alloy thereof. The heat sink 20 has an elongated cylinder 22 with a through hole (not labeled) defined therein. The heat sink 20 has a plurality of conducting arms 24 evenly extending outwardly from a circumferential surface of the cylinder 22. The conducting arms 24 are identical and centrosymmetric to each other relative to an axis of the cylinder 22. The conducting arms 24 have a number which is consistent with that of the LED modules 30 in the preferred embodiment, and can be different in different embodiments. In this embodiment, the numbers of the conducting arms 24 and the LED modules 30 are both six. A plural pairs of first fins 26 are formed on two opposite lateral sides of each of the conducting arms 24. Each pair of the first fins 26 extend outwardly and perpendicularly from two lateral sides of a corresponding conducting arm 24 and are symmetrical to each other relative to the corresponding conducting arm 24. The first fins 26 at a lateral side of each of the conducting arms 24 increase in length outwardly from the cylinder 22 to a distal end of the corresponding conducting arm 24. Each of the conducting arms 24 has a distal end terminating at an inside face of an outmost first fin 26 thereof. An outside face (not labeled) of each outmost first fin 26 is flat and used for thermally contacting with one of the LED modules 30, when the LED module 30 is mounted on the outside face. Three elongated ridges 23 extend inwardly from an interior surface of the cylinder 22 of the heat sink 20 and are evenly distributed at the cylinder 22. Each of the ridges 23 therein defines a vertical mounting orifice 230.

[0018] Referring to FIGS. 2 and 3 again, the LED modules 30 are respectively attached to the outer faces of the fins 26 of the heat sink 20, and each comprises an elongated printed circuit board 32 with a size corresponding to that of the outmost first fin 26 of the heat sink 20 and a plurality of LED components 34 which are mounted on the printed circuit board 32 and arranged in a line along a length of the printed circuit board 32.

[0019] The cover 40 is secured on the top of the heat sink 20 and comprises a circular plate 42 and a plurality of second fins 44 arranged on the plate 42. Corresponding to the mounting orifices 230 in the ridges 23 of the heat sink 20, three through orifices 430 are defined in the plate 42. Three screws 46 are brought to extend through the through orifices 430 to engage into the mounting orifices 230 to thereby fix the cover 40 to the top of the heat sink 20. An annular inner protrusion 422 and an annular outer protrusion 424 concentric with the inner protrusion 422 extend downwardly from a bottom surface of the plate 42. The inner protrusion 422 and the outer protrusion 424 are spaced from each other, thereby defining a second groove 426 therebetween. The second groove 426 is in alignment with the first groove 126 of the lamp holder 10 and engagingly receives an upper end of the envelope 50. The second fins 44 are parallel to each other and extend perpendicularly from a top surface of the plate 42. A plurality of spaced channels (not labeled) is defined in the second fins 44 for facilitating airflow taking heat away from the second fins 44 into ambient air. Corresponding to the first securing holes 128 in the base 12 of the lamp holder 10, three second securing holes 428 are defined in the plate 42 for receiving upper ends of the connecting shafts 200.

[0020] The envelope 50 has a tubular shape with a through hole (not labeled) defined therein. A diameter of the envelope 50 decreases gradually from a middle toward two opposite ends of the envelope 50. The two opposite ends of the envelope 50 each have a shape substantially similar to that of a corresponding one of the first and second grooves 126, 426. The envelope 50 is made of a transparent or semitransparent material such as glass, plastic, etc., for allowing the light emitted by the LED module 30 traveling therethrough to illuminate a surrounding environment.

[0021] The first and second cushions 100, 102 respectively have configurations which are similar to those of the first and second grooves 126, 426, respectively. The first and second cushions 100, 102 are received fitly in the first and second grooves 126, 426, respectively. The first and second cushions 100, 102 respectively define recesses (not labeled) at top and bottom surfaces thereof facing the lower and upper ends of the envelope 50, respectively. The lower and upper ends of the envelope 50 are interferingly fixed into the recesses of the first and second cushions 100, 102.

[0022] Each of the connecting shafts 200 has a shape of an elongated post and forms screw thread on two opposite ends thereof for respectively engaging with two nuts 202.

[0023] In assembly, the driving circuit module 300 is placed in the receiving chamber 120 of the lamp holder 10. The heat sink 20 has a lower end snugly received in the receiving chamber 120 of the lamp holder 10 and enclosing the driving circuit module 300 therein. The LED modules 30 are respectively attached to the outer faces of the first fins 26 of the heat sink 20 in a thermal conductive relationship. The envelope 50 encloses the heat sink 20 assembled with the LED modules 30. The cover 40 then is coupled onto the heat sink 20 and the envelope 50. The first and second cushions 100, 102 are respectively received in the first and second grooves 126, 426. The first cushion 100 is sandwiched between the envelope 50 and the lamp holder 10; the second cushion 102 is sandwiched between the envelope 50 and the cover 40. Two opposite ends of each of the connecting shafts 200 respectively extend through the first and second securing holes 128,428 and respectively engage with two nuts 202 to securely connect the lamp holder 10 and the cover 40.

[0024] In operation, heat generated by the LED modules 30 is conducted to the heat sink 20 and then reaches the cover 40 via the heat sink 20. The heat is finally dissipated into ambient through the second fins 44 of the cover 40. The first and second cushions 100, 102 are respectively in the first groove 126 of the lamp holder 10 and the second groove 426 of the cover 40. The upper and lower ends of the envelope 50 tightly engaged into the recesses of the first and second cushions 100, 102, thereby enhancing waterproof function of the LED lamp. Furthermore, by locking the nuts 202 with the connecting shafts 200 as tightly as possible, wherein the nuts 202 are respectively located above the cover 40 and below the lamp holder 10, the lamp holder 10 and the cover 40 can be forced to move toward each other, thereby further reinforcing the hermetic connection between the envelope 50 and the cover 40 and between the envelope 50 and the lamp holder 10.

[0025] It is believed that the present embodiments and their 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.