Liquid cooled LED systems

• US 9,435,524 B2
• Filed: 04/23/2012
• Issued: 09/06/2016
• Est. Priority Date: 12/30/2011
• Status: Active Grant

• Current Assignee: IDEAL Industries Lighting, LLC (Ideal Industries Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Athalye, Praneet
• Primary Examiner(s): MAY, ROBERT J
• Application Number:
  US13/453,577
• Publication Number:
  US 20130170176A1
• Time in Patent Office: 1,597 Days
• Field of Search: 362/294, 362/373, 362/218, 362/547, 362/267
• US Class Current: 1/1
• CPC Class Codes: F21K 9/232 specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• CPC Class Codes: F21K 9/233 specially adapted for generating a spot light distribution, e.g. for substitution of reflector lamps
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21K 9/90 Methods of manufacture
• CPC Class Codes: F21V 21/30 Pivoted housings or frames
• CPC Class Codes: F21V 29/506 of globes, bowls or cover glasses
• CPC Class Codes: F21V 29/56 using liquid coolants F21V29/51 takes precedence
• CPC Class Codes: F21V 29/58 characterised by the coolants
• CPC Class Codes: F21V 29/59 with forced flow of the coolant
• CPC Class Codes: F21V 3/00 Globes; Bowls; Cover glasses with refracting properties F21V5/00; with reflecting properties F21V7/00; characterised by cooling arrangements F21V29/506
• CPC Class Codes: F21V 3/12 the coatings comprising photoluminescent substances
• CPC Class Codes: F21Y 2101/00 Point-like light sources
• CPC Class Codes: F21Y 2107/00 Light sources with three-dimensionally disposed light-generating elements
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]

Abstract

Liquid cooled LED systems are disclosed. Embodiments of the invention provide an LED lighting system in which the LED devices are cooled by circulating liquid or fluid. In example embodiments, a flow return member provides a way for a fluid medium to enter and exit an envelope containing the LED devices. An additional cooling mechanism, such as a radiator or thermoelectric cooler can be provided. The optically transmissive fluid medium can be, for example, oil or a fluorinated or halogenated liquid or gel, and can optionally provide index matching. The fluid medium can optionally include a phase change material in order to enhance cooling. In some embodiments, a pump is used to circulate the fluid medium. However, the optical envelope and/or the flow return member could also be oriented so that the fluid medium circulates by gravity and/or temperature difference.

Claims

1. A lighting system comprising:

a tubular optical envelope;

an array of LED devices without a submount or other carrier within the optically transmissive envelope to be operable to substantially emit omnidirectional light when energized;

an optically transmissive fluid medium in thermal communication with the array of LED devices; and

a flow return member in fluid communication with the tubular optical envelope so that the optically transmissive fluid medium can circulate through the optically transmissive envelope, the flow return member further comprising a plurality of metal coils through which the optically transmissive fluid passes, the plurality of metal coils being external to the tubular optical envelope.

2. The lighting system of claim 1 further comprising a thermoelectric cooler in thermal communication with the optically transmissive fluid medium.

3. The lighting system of claim 1 further comprising a pump in fluid communication with at least one of the tubular optical envelope and the flow return member.

4. The lighting system of claim 1 wherein at least one of the optically transmissive envelope and the flow return member is oriented so that the fluid medium circulates by at least one of gravity and temperature difference.

5. The lighting system of claim 1 wherein the optically transmissive fluid medium comprises at least one of oil and a fluorinated or halogenated liquid or gel.

6. The lighting system of claim 5 wherein the optically transmissive fluid medium is an index matching medium.

7. The lighting system of claim 5 further comprising phosphor disposed within or on the tubular optical envelope.

8. The lighting system of claim 7 wherein the tubular optical envelope further comprises neodymium oxide so that the envelope filters light to exhibit a spectral notch between 520 nm and 605 nm.

9. The lighting system of claim 5 wherein the array of LED devices further comprises a plurality of LED devices connected in series.

10. The lighting system of claim 9 wherein the electrical connection is configured to supply the array of LED devices with alternating current.

11. The lighting system of claim 9 wherein the electrical connection is configured to supply the array of LED devices with direct current.

12. The lighting system of claim 1 wherein the optically transmissive fluid medium comprises a phase change material.

13. The lighting system of claim 1 wherein the array of LED devices further comprises a plurality of LED devices connected in parallel.

14. The lighting system of claim 13 wherein the flow return member and optically transmissive envelope are configured so that the optically transmissive fluid medium circulates in a direction that opposes a voltage drop through the plurality of LED devices.

15. The lighting system of claim 1 further comprising:

an internal envelope between the tubular optical envelope and the array of LED devices; and

an internal coolant disposed in the internal envelope.

16. The lighting system of claim 15 wherein the internal coolant comprises at least one of oil and a fluorinated or halogenated liquid or gel.

17. The lighting system of claim 16 wherein the optically transmissive fluid medium comprises water.

18. A light fixture comprising:

an optically transmissive tubular envelope;

a linear array of LED devices without a submount or other carrier disposed in the tubular envelope to be operable to substantially emit omnidirectional light when energized;

a reflector configured to reflect the omnidirectional light from the linear array of LED;

an optically transmissive fluid medium in thermal communication with the linear array of LED devices;

a flow return member in fluid communication with the tubular envelope so that the optically transmissive fluid medium can circulate through the tubular envelope, the flow return member further comprising a plurality of metal coils through which the optically transmissive fluid passes, the plurality of metal coils being external to the tubular envelope; and

a power supply connected to the linear array of LED devices.

19. The light fixture of claim 18 further comprising a thermoelectric cooler in thermal communication with the optically transmissive fluid medium.

20. The light fixture of claim 18 wherein the optically transmissive fluid medium comprises at least one of oil and a fluorinated or halogenated liquid or gel.

21. The light fixture of claim 20 wherein the optically transmissive fluid medium is an index matching medium.

22. The light fixture of claim 18 wherein the linear array of LED devices further comprises a plurality of LED devices connected in series.

23. The light fixture of claim 18 wherein the linear array of LED devices further comprises a plurality of LED devices connected in parallel.

24. The light fixture of claim 23 wherein the flow return member and optically transmissive tubular envelope are configured so that the optically transmissive fluid medium circulates in a direction that opposes a direction of voltage drop through the plurality of LED devices.

25. A method of operating an LED lighting system, the method comprising:

energizing a linear LED array comprising a plurality of LEDs without a submount or other carrier so that the plurality of LEDs substantially emit omnidirectional light;

circulating an optically transmissive fluid through a tubular optical envelope surrounding the linear LED array so that the LED array substantially emits the omnidirectional light through the optically transmissive fluid medium and the tubular optical envelope; and

dissipating heat from the optically transmissive fluid by circulating the optically transmissive fluid medium through a flow return member comprising a plurality of metal coils through which the optically transmissive fluid passes, the plurality of metal coils being external to the tubular optical envelop.

26. The method of claim 25 further comprising energizing a phosphor.

27. The method of claim 26 further comprising filtering a visible light intensity using neodymium oxide so that the intensity is comparatively reduced within a predetermined part of a spectrum of visible light.

28. The method of claim 25 wherein at least one of the circulating of the optically transmissive fluid through the tubular optical envelope and the circulating of the optically transmissive fluid through the flow return member further comprises pumping the optically transmissive fluid.

29. The method of claim 25 wherein the circulating of the optically transmissive fluid through the optical envelope further comprises circulating the optically transmissive fluid in a direction that opposes a voltage drop in the linear LED array.