WO2011028805A2

WO2011028805A2 - Cooled led lighting assemblies

Info

Publication number: WO2011028805A2
Application number: PCT/US2010/047537
Authority: WO
Inventors: David Sooil Koh
Original assignee: Savenergy Inc.
Priority date: 2009-09-01
Filing date: 2010-09-01
Publication date: 2011-03-10
Also published as: WO2011028805A3

Abstract

An LED assembly in which a heat pipe moves heat from an LED to a distal heat sink. A Light Emitting Diode (LED) 451 is mounted to a lighting surface, such as a circuit board 411. The LED is in thermal contact with a heat pipe 410 running adjacent to and in thermal contact with LED. A conductive metal structure 420, 414 serves as a distal heat sink. The heat pipe 410 extends from the LED to the heat sink, to conduct heat efficiently from the LED to the heat sink.

Description

Cooled LED Lighting Assemblies

The present invention relates to LED (Light Emitting Diode) illumination systems, particularly illumination systems having cooling devices to improve the LED's efficiency.

Fig. 1 is an oblique perspective view of an embodiment of a light assembly of the present invention.

Fig. 2 is a front perspective view of this embodiment. Fig. 3 is a side perspective view of this embodiment. Fig. 4 is a bottom perspective view of this embodiment.

Fig. 5 is an elevation in section of another embodiment of a screw-in light bulb of the present invention through plane 5 of Fig. 6.

Fig. 6 is a top plan view thereof through the plane 6 of Fig. 5, showing a fin assembly used in a prototype, having curved fins.

Fig. 7 is a side perspective view of a fin assembly of an embodiment similar to fig. 5, having curved fins.

Fig. 8 is a cut away perspective view thereof. Fig. 9 is a top oblique perspective view thereof.

Fig. 10 is a bottom plan view of the circuit board of that embodiment with some LEDs applied.

Fig. 11 is a side elevation of a similar and presently preferred embodiment having planar fins rather than curved fins.

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Specification September 1 , 2010 (2:3 1pm) Fig. 12 is an exploded view thereof.

Fig. 13 is an oblique perspective view of a heat pipe used in this embodiment.

Fig. 14 is an oblique perspective view of a center tube for mounting the heat pipes used in this embodiment.

Fig. 15 is a perspective view of the fin assembly, having straight fins.

Fig. 16 is a bottom plan view of the preferred embodiment as of September 1, 2010.

Fig. 17 is a side elevation of part thereof from plane 17 of fig. 16.

Fig. 18 is a is a side elevation in section through plane 18 of fig. 16.

Fig. 19 is an elevation in partial section of another embodiment of a LED assembly of the present invention designed for use in a florescent tube fixture. Fig. 20 is a side elevation in section through plane 20 of fig. 19.

Detailed Description

The present invention contemplates using an LED Assembly in which LEDs are adjacent heat pipes, which are preferably wick type heat pipes, comprising a fluid such as acetone or deionized water, in an evacuated copper pipe. The fluid condenses when cool, and evaporates when heated, and thereby moves heat very rapidly around the hot side of an optional Peltier device. The wick in the pipe renders it even more efficient at heat transfer. The heat pipe carries heat from the LEDs to distal heat sinks for dissipation in the ambient fluid medium, such as air. These heat sinks are generally aluminum, but may be of any metal that is a good heat conductor.

Specification September 1 , 2010 (2:3 1pm) The invention contemplates a optional Peltier cooling element, powered by wires, to pump heat from an LED to the heat pipe or from heat pipe to heat sink, but, so far, the presently preferred embodiments seem to work better without the thermocouples of the Peltier cooling blanket, and Peltier effect devices have therefore been mostly omitted from our present detailed description of the presently embodiments.

By cooling the LEDs down to a maximum of 40 degrees C, the device increases LED light vs. power efficiency, significantly.

Detailed Description Prototype

Fig. 1 shows a prototype, generally designated 50. On the top surface 52 is a plurality of Light Emitting Diode (LED) strips 61-75.

As in Fig. 1 a power supply 120 converts 120 VAC power to 12 VDC to power the LEDs 61- 75 and the thermocouple 1 10. This power supply be changed for different power systems, such as 220 volts in Europe. For use on a 12 volt boat or car, voltage conversion would not be needed.

The thermocouple 110 is optional, and may be omitted.

Fig. 1 details top surface 52. In this prototype the LEDs 61-75 are wired in series by wires 81-84 and soldered to the LED strips 61-75. We envision using printed circuits in the preferred embodiments.

In this prototype the LEDs 61-75 are screwed to the top surface by screws 86. We envision using thermal epoxy or similar heat-conductive adhesive.

Specification September 1 , 2010 (2:3 1pm) The LEDs 61-75 give off heat, but are most efficient when cool. LEDs are housed between three heat conductive metal blocks, such as aluminum blocks 88-90. These are mounted on finned heat sink 92, to dissipate some of the heat generated by the LEDs, fig. 4.

To further dissipate some of the heat generated by the LEDs heat pipes 101-102 run beneath LEDs 61-75 as in Fig. 1, and continue down to heat sinks 103-104 as in figs. 4-6, to conduct heat efficiently to finned heat sinks 92 & 103-104.

As in Fig. 2, a layer 110 between: aluminum blocks 88-90 that form top surface 52, and heat sink 92 is an optional Peltier thermocouple 110. When voltage is applied across thermocouple 110 with proper polarity, the optional Peltier thermocouple 110 pumps heat from the blocks 88- 90 and the pipes 101-102 to heat sink 92, making the heat sink hotter than the LEDs to radiate more heat and to actively cool the LEDs. LEDs are much more efficient, the colder they are. Fig. 4 is a bottom plan view showing the three finned heat sinks 92 & 103-104.

For Light Socket

Fig. 5 shows an embodiment, generally designated 200, for screwing into an ordinary Edison light socket. A standard Edison screw-base 202 for a 120 VAC light bulb supplies 120 VAC to a power supply 204, which converts to 12 VDC. Wires 211-212 supply the 12 VDC to the arrays of LEDs 214 below.

In other embodiments, bases may be provided for other types of light sockets, along with

Specification September 1 , 2010 (2:3 1pm) power supplies for their corresponding other voltage systems.

Over each LED 214 is a heat pipe 221-228, which radiates inward from the LEDs 214. Each heat pipe bends as shown in dotted for pipe 228, and rises up within a central aluminum heat sink 230 shown in partial section.

Finned radiator 240 slides over the heat sink 230. Radiator 240, and its multiplicity of radiating fins 242 are shown in side elevation in figs. 5; in top plan in fig. 6.; in side perspective in fig. 7, section in Fig. 8; and top oblique perspective in Fig. 9. Figs. 6-9 are from photos of a radiator having curved fins 242, but these can alternatively be straight fins as 414 in figs. 11, 12 & 15.

As in bottom plan Fig. 10, each LED 214 is part of an array in which the LEDs 214 are mounted on a circuit board 252 mounted beneath a heat pipe such as 221. This arrangement repeats in eight radii around the base 254. Bezel 256 is wrapped around base 254 and secures base 254 to the circumference of radiator 240.

Fig. 11 is a side elevation of a slightly different and presently preferred embodiment of the socket-based bulb, showing base 462, and lens or cover 433.

Fig. 12 is an exploded view thereof. It shows the heat pipes 410, shown isolated in fig. 13, which radiate from lower arm 410A centerward, to bend 410B, up shaft 410C. As in fig. 12, these heat pipes 410 are located behind 10" diameter circuit board 411, which is 1/32" thick, by mount 412 in slots 413 of mount 412. shafts 410C are inserted into fins 414, after being inserted into hollow metal core 420 in channels 422. The core 420 is shown isolated in fig. 14 and helps as a heat sink, in conjunction with the fins 414 which heat sink and radiate heat.

Specification September 1 , 2010 (2:3 1pm) We presently prefer aluminum for this core 420. The core 420 and fins 414 togeter serve as a distal heat sink.

Bezel 430 binds clear cover or lens 433 (as appropriate for flood or spot light purposes) to circuit board 411, mount 412, and fins 414.

Fig. 13 is an oblique view of a heat tube 410, which tube 410 radiates inward from lower arm 41 OA centerward, to bend 410B, and up shaft 4 IOC.

Fig. 14 is an oblique top-side view showing the top ends 41 OA of heat pipes 410 and insert 422.

Fig. 16 shows circuit board 411, including annular conductors 441-444. LEDs 451 span between and are powered by conductors 441-442. LEDs 452 span between and are powered by conductors 443-444.

As in Fig. 11 the DC power supply resides within neck 460 which screws into 110 VAC Edison screw-base 462. Power is wired to the circuit board 422 which powers LEDs 451- 452. The LEDs generate heat which reduces their efficiency.

This heat is transmitted through the 1/32" thin circuit board 411 to heat pipes 410, each located directly behind a radius of LEDs. The heat pipe fluid evaporates quickly in the vacuum pipe 410 to conduct heat to core 420 and fins 414, which radiate it away into the ambient fluid, such as convective air.

Another embodiment, presently preferred as of March 5, 2010 is shown in Figs. 16-18. Holes are cut in circuit board 411 so that inner LEDs 451 and outer LEDs 452 can be

Specification ^' September 1 , 2010 (2:3 1pm) mounted flush with top surface 520 of circuit board 411, as in Fig. 18. This allows heat pipe 410 to mount directly against the LED's such as 452 for maximum heat transfer from LED to heat pipe 410. Thermal grease 530 has been applied therebetween, to further help said heat transfer. Joints 510 electrically-conductively and structurally attach the LEDs 451-452 to board 411, as by solder, screws, or other fastening means.

As in Fig. 16 , current flows from inner ring 441, through LED 451, to inner-middle ring 442, and from outer middle ring 443 to through outer LED outer ring 444.

Fig. 17 is a side elevation of part thereof from plane 24.

Fig. 18 is a is a side elevation in section through plane 25 of that part thereof.

LED's For a Florescent Light Socket

Figs. 19 and 20 show a light tube 300 for a florescent light socket. Electricity is supplied by probes 302 to the tube 300. Power supply 304 converts it to DC, transmitted through circuit board 306 to LEDs 308. A flat but malleable heat pipe 310 is bent to fit within aluminum heat sink 312 having fins 314 to radiate heat. Heat pipe 310 transmits the heat efficiently from LEDs 308, making the LEDs cooler and more efficient.

Of the tube cylinder, the arc that is not occupied by heat sink 312 is a clear plastic cover 320. No mercury or gas contained therein, so the glass sealed tube of a florescent bulb is not required to contain the toxic atmosphere that would reside within a florescent tube.

End caps 330 cover the ends of the tube 300 and mount the probes 302.

Specification September 1 , 2010 (2:3 1pm)

Claims

Claims Koh-5-PCT

1. An LED assembly in which a heat pipe moves heat from an LED to a distal heat sink.

2. An LED assembly according to claim 1 having:

a lighting surface 52, 411;

said lighting surface comprises a plurality of LED strips 61-67, 451-452;

a heat pipe 102, 410 running adjacent to and in thermal contact with LEDs;

a conductive metal structure 103, 420, 414 for use as a distal heat sink;

said heat pipe extending from the LEDs to the conductive metal structure, to conduct heat efficiently from the LEDs to the distal heat sink.

3. An LED assembly according to claim 2 in which a proximal conductive metal structure 88- 90, 92 comprises the lighting surface 88-90 and a proximal heat sink 92.

4. An LED assembly according to claim 3 in which a Peltier thermocouple 110 is located between the heat pipe and one of the heat sinks.

5. An LED assembly 200 according to claim 1 for mounting into a light bulb socket, said LED assembly including:

a base 202 for engaging said light bulb socket;

the distal heat sink extending from the base 202;

the heat pipe thermally coupling to said distal heat sink;

said heat pipe extending from said heat sink;

said heat pipe extending to an LED; Claims Koh-5-PCT said heat pipe thermally coupling to said LED.

6. An LED assembly 200 according to claim 5 in which:

there is a plurality of the LED;

the LEDs of the plurality are mounted in a radial array on a circuit board;

there is a plurality of the heat pipe;

each heat pipe 221-228 radiates inward adjacent the circuit board 412 from at least one LED; each heat pipe bends and extends perpendicular to the circuit board within a central heat sink 230;

a finned radiator 240 radiates a plurality of fins out from the central heat sink 230.

7. An LED assembly according to claim 6 in which:

each LED is part of a radial array in which the LEDs 214 are mounted on the circuit board; a mount comprises a plurality of radial channels;

each channel locates one of the heat pipes to its radius adjacent the circuit board;

each LED is mounted adjacent a heat pipe.

8. An LED assembly according to claim 7 in which each heat pipe has more than one LED's along its radius.

9. An LED assembly according to claim 7 in which:

a bezel 430 binds a clear cover to circuit board 411, mount 412, and fins 414.

10. An LED assembly according to claim 7 in which: a bezel 430 binds a lens 433 to circuit board 411, mount 412, and fins 414. Claims Koh-5-PCT

11. An LED assembly according to claim 8 in which:

each heat pipe has two LEDs;

the circuit board 411, includes four annular conductors 441-444;

each LEDs 451 spans between and is powered by conductors 441-442; and

each LEDs 452 spans between and is powered by conductors 443-444.

12. An LED assembly according to claim 8 in which:

a DC power supply resides within a neck 460 which is adjacent the socket base.

13. An LED assembly according to claim 12 in which:

the socket base is a 110 VAC Edison screw-base 462.

14. An LED assembly according to claim 7 in which:

the circuit board is a 1/32" thin circuit board 411;

the LEDs transmit heat through the 1/32" thin circuit board 411 to the heat pipes 410

15. An LED assembly according to claim 7 in which:

holes are cut in circuit board 411 so that inner LEDs 451 and outer LEDs 452 can be mounted flush with top surface 520 of circuit board 411, as in Fig. 18, to mount heat pipe 410 directly against the LED's for maximum heat transfer from each LED to heat pipe 410.

16. An LED assembly according to claim 1 including:

a cylindrical light tube 300 for a florescent light socket; Claims Koh-5-PCT said light tube has probes for tapping power from the fiorescent light socket; a power supply 304 converts said power to DC, said power is transmitted through circuit board 306 to LEDs 308, mounted on said circuit board; said circuit board is mounted to a bendable flat heat pipe 310; said bendable flat heat pipe 310 is bent to fit within an conductive metal heat sink 312; the conductive metal heat sink has fins 314 to radiate heat; a clear cover 320 occupies an arc of the cylindrical light tube 300 facing the LEDs on the circuit board

11. An LED assembly according to claim 10 in which: end caps 330 cover the ends of the tube 300 and mount the probes 302.

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