LED illumination device

1. Technical Field

The disclosure generally relates to light emitting diode (LED) illumination devices, and particularly to an LED illumination device with highly efficient heat dissipation.

2. Description of Related Art

LEDs (light emitting diodes) are often preferred for use in illumination devices rather than CCFLs (cold cathode fluorescent lamps) due to their high brightness, long lifespan, and a wide color range.

For an LED, 80 to 90% of the power consumed by the LED is expended as thermal energy, with only the remaining 10 to 20% of the power consumed providing visible light. In addition, a plurality of LEDs are generally packaged in a single LED illumination device to obtain desired brightness.

Accordingly, high brightness LED illumination devices require highly efficient heat dissipation for timely and adequate removal of the heat generated to avoid impaired performance and even device failure. Frequently used heat dissipation devices such as heat sinks, fans, and combinations thereof may be unable to provide sufficient heat dissipation for the high brightness LED illumination device, in addition to frequently consuming unacceptable levels of energy.

FIG. 1 is a cross-section of an LED illumination device in accordance with a first embodiment of the disclosure.

FIG. 2 is a cross-section of an LED illumination device in accordance with a second embodiment of the disclosure.

FIG. 3 is a cross-section of an LED illumination device in accordance with a third embodiment of the disclosure.

FIG. 4 is a cross-section of an LED illumination device in accordance with a fourth embodiment of the disclosure.

Reference will now be made to the drawing figures to describe the various embodiments in detail.

FIG. 1 is a cross-section of an LED illumination device 100 in accordance with a first embodiment of the disclosure. The LED illumination device 100 includes an optical section 10 , an electrical section 30 , and a heat dissipation section 20 therebetween. The LED illumination device 100 is substantially cylindrical. The optical section 10 is disposed at a bottom end of the LED illumination device 100 and the electrical section 30 is disposed at a top end thereof.

The optical section 10 includes a housing 122 , a light reflector 121 , a light source 11 , and an optical lens 124 . A top end of the housing 122 is coupled to the heat dissipation section 20 , and a bottom end of the housing 122 is sealed by the optical lens 124 . The light reflector 121 and the light source 11 are received in the housing 122 . The housing 122 provides protection for the light source 11 and the light reflector 121 . In this embodiment, the light source 11 includes a plurality of light emitting diodes (LEDs). The light reflector 121 is conical, tapering from a bottom end to a top end thereof. The top end of the light reflector 121 , adjacent to the heat dissipation section 20 , defines an opening 123 receiving the light source 11 , and the bottom end of the light reflector 121 is received on the bottom end of the housing 122 . The light reflector 121 and the optical lens 124 provide luminescence for the light source 11 .

The electrical section 30 provides power, control circuitry, and power management for the light source 11 , and includes a casing 32 , a lamp head 33 , a mounting plate 34 , a circuit board 31 and a dustproof cover 35 . A bottom end of the casing 32 is attached to the heat dissipation section 20 , and a top end thereof receives the lamp head 33 . The mounting plate 34 is mounted at the bottom end of the casing 32 between the electrical section 30 and the heat dissipation section 20 . A plurality of air exchanges 341 is defined in the mounting plate 34 , communicating the electrical section 30 with the heat dissipation section 20 . A plurality of exhaust ports 322 is defined in the casing 32 adjacent to the lamp head 33 of the casing 32 . The exhaust ports 322 communicate an interior of the electrical section 30 with an external environment of the LED illumination device 100 and dissipate heat from the circuit board 31 . The circuit board 31 is mounted in the casing 32 of the electrical section 30 through a mounting mechanism which includes a socket 321 and a connecting post 311 . The socket 321 is attached to an inner surface of the casing 32 . The connecting post 311 connects the circuit board 31 with the socket 321 . The dustproof cover 35 covers an outer side of the exhaust ports 322 of the casing 32 , preventing entry of airborne contaminants into the interior.

The electrical section 30 is further provided with a plurality of electrical wires 312 , 111 connected with the circuit board 31 . The electrical wires 111 extend through the mounting plate 34 and electrically connect the lamp head 33 with the light source 11 , providing operating power thereto.

The heat dissipation section 20 is provided with a heat sink 23 , including a columnar metal base 231 and a plurality of metal fins 232 extending radially and outwardly from an outer circumferential surface of the metal base 231 . The metal base 231 has a top surface contacting the mounting plate 34 of the electrical section 30 and a bottom surface contacting the light source 11 . A blind hole 233 is defined at an upper portion of the metal base 231 to increase the heat exchange surface of the heat sink 23 . The blind hole 233 communicates with the electrical section 30 via the air exchanges 341 , and extends vertically and inwardly from the top surface of the metal base 231 . The blind hole 233 gradually decreases in size from the top surface of the metal base 231 towards the bottom surface of the metal base 231 , which has a smooth, curved inner surface 235 . A plurality of air venting channels 234 is radially defined in a lower portion of the metal base 231 . Each of the air venting channels 234 communicates a bottom of the blind hole 233 with an external environment of the metal base 231 . The heat sink 23 is preferably aluminum or aluminum alloy manufactured via extrusion.

The light source 11 and the top end of the light reflector 121 are mounted on the bottom surface of the metal base 231 of the heat sink 23 . The heat dissipation section 20 and the light source 11 cooperatively form a light engine 21 for the LED illumination device 100 . During operation of the LED illumination device 100 , heat generated by the light source 11 is conducted to the heat sink 23 via the metal base 231 directly, whereby air in the heat dissipation section 20 , that is, in the spaces formed between each two neighboring metal fins 232 and the blind hole 233 , is heated by the transferred heat of the light source 11 and rises accordingly, exiting to the electrical section 30 via the air exchanges 341 of the mounting plate 34 , and further to ambient atmosphere via the exhaust ports 322 of the casing 32 . Simultaneously, cool air in the ambient atmosphere is drawn into the spaces between each two neighboring metal fins 232 , and enters the blind hole 233 via the air venting channels 234 by the resulting air pressure differential. The resulting convection circulating through the heat dissipation section 20 rapidly dissipates heat generated from the light source 11 into the ambient environment.

FIG. 2 is a cross-section of an LED illumination device 100 a in accordance with a second embodiment of the disclosure, differing from the previous embodiment only in that a heat dissipation section 20 a further includes a mounting seat 42 , a U-shaped heat pipe 24 , and two through holes 235 provided in the metal base 231 of the heat sink 23 . Each of the through holes 235 extends from the top surface of the metal base 23 to the bottom surface of the metal base 23 . The heat pipe 24 includes an evaporating portion 241 and two condensing sections 242 extending upwardly and perpendicularly from two opposite ends thereof. The condensing sections 242 of the heat pipe 24 are thermally received in the through holes 235 of the metal base 23 .

The mounting seat 42 interconnects the metal base 231 with the light source 11 . The mounting seat 42 includes a top mounting block 421 and a bottom mounting block 422 . A top surface of the top mounting block 421 is directly attached to the bottom surface of the metal base 231 , whereby the top mounting block 421 can directly transfer heat to the metal base 231 . A bottom surface of the top mounting block 421 is provided with a semi-circular groove (not labeled). A top surface of the bottom mounting block 422 is provided with a semi-circular groove (not labeled) corresponding to the semi-circular groove of the top mounting block 421 . When the top and the bottom mounting blocks 421 , 422 are mounted together, the semi-circular grooves cooperatively form a circular groove receiving the evaporating section 241 of the heat pipe 24 therein. Alternatively, the top mounting block 421 and the bottom mounting block 422 can be integrally formed as a single metal block with a circular groove defined therethrough receiving the evaporating section 241 of the heat pipe 24 . In this case, the heat pipe 24 is originally straight, and then bent to have the U-shaped configuration after the straight heat pipe is inserted into the circular groove.

In the present LED illumination device 100 a , the heat pipe 24 effectively removes heat generated by the light source 11 . The heat of the light source 11 is initially transferred to the bottom mounting block 422 . A portion of the heat transferred to the bottom mounting block 422 is thereafter transferred to the top mounting block 421 , and then to the metal base 231 via the top mounting block 421 . Another portion of the heat transferred to the bottom mounting block 422 is thereafter rapidly transferred to the evaporating portion 241 of the heat pipe 24 , and then to the metal base 231 via the heat pipe 24 . The heat is finally and effectively dissipated by the heat dissipation section 20 a via the natural air convection circulated therethrough.

FIG. 3 is a cross-section of an LED illumination device 100 b in accordance with a third embodiment of the disclosure, differing from the previous embodiment only in that a heat dissipation section 20 b includes a mounting seat 42 b , a plurality of parallel, stacked fins 53 arranged on the top surface of the mounting seat 42 b , and two U-shaped heat pipes 24 (only one heat pipe 24 is visible in FIG. 3 ). Each of the heat pipes 24 includes an evaporating section 241 and two condensing sections 242 extending upwardly and perpendicularly from two opposite ends thereof. The mounting seat 42 b has a configuration differing from mounting seat 42 described in the second embodiment in that two grooves (only one groove is visible in FIG. 3 ) receive the evaporating sections 241 of the two heat pipes 24 therein, respectively. The fins 53 are cooperatively provided with four through holes 235 b (only two through holes 235 b are visible in FIG. 3 ) receiving the condensing sections 242 of the heat pipes 24 therein. Each of the fins 53 includes a planar main body 532 perpendicular to the condenser sections 242 of the heat pipes 24 , and two protruding members 531 protruding upwardly from a top surface of the main body 532 towards an adjacent upper main body 532 . Each of the protruding members 531 defines a vent 533 therein. Each vent 533 communicates with two opposite sides of corresponding main body 532 . Thus, when air between the fins 53 is heated by heat transferred from the light source 11 through the heat pipes 24 , the warm air rises through the air exchanges 533 to a top side of the fins 53 , and then through the air exchanges 341 of the mounting plate 34 into the electrical section 30 , and finally to the exterior through the exhaust ports 322 of the electrical section 30 .

FIG. 4 is a cross-section of an LED illumination device 100 c in accordance with a fourth embodiment of the disclosure, differing from the previous embodiment only in that a heat dissipation section 20 c includes a mounting seat 62 , a plurality of parallel, stacked fins 63 on the top surface thereof, and a straight heat pipe 64 . The heat pipe 64 is columnar, and includes an evaporation section 641 and a condenser section 642 formed at bottom and top ends thereof, respectively. The bottom surface of the evaporation section 641 is planar, and thermally contacts the top surface of the mounting seat 62 . The mounting seat 62 has a configuration differing from mounting seat 42 described in the second embodiment in that no groove is defined in the mounting seat 62 to receive the evaporating section 641 of the heat pipe 64 . Alternatively, the mounting seat 62 can define a straight through hole receiving the evaporating section 641 of the heat pipe 64 therein, such that the bottom surface of the evaporating section 641 thermally contacts the light source 11 directly. Each of the fins 63 is umbrella-shaped and includes a planar main body 632 perpendicular to the condenser section 642 of the heat pipe 64 and two flanges 633 angling downwards from two opposite edges of the main body 632 , respectively. The main body 632 of each fin 63 defines a central hole (not labeled) receiving the condenser section 642 of the heat pipe 64 therein. A protruding member 631 extends upwardly and perpendicularly from a top surface of each of the flanges 633 towards the air exchanges 341 of the electrical section 30 . Each of the protruding members 631 defines a vent 635 therein. Each of the vents 635 communicates with two opposite sides of a corresponding fin 63 which defines the vent 635 . Thus, when air between the fins 63 is heated by transferred heat of the light source 11 , the warm air rises through the vents 635 to a top side of the fins 63 , and then through the air exchanges 341 of the mounting plate 34 into the electrical section 30 , and finally to the exterior through the exhaust ports 322 of the electrical section 30 .

It is to be understood, however, that even though numerous characteristics and advantages of the disclosure have been set forth in the foregoing description, together with details of the structure and function of the embodiments, the disclosure is illustrative only, and 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.