LED light fixture

An LED light fixture including at least one LED light source thermally coupled to a heat-conductive structure. The heat-conductive structure having an LED-supporting region and heat-dissipating surfaces extending away therefrom. The at least one LED light source is thermally coupled to the LED-supporting region. The heat-conductive structure defines venting apertures bordering the at least one LED light source to facilitate ambient fluid flow to and from the heat-dissipating surfaces. In some embodiments, the LED light fixture includes a protrusion extending into a corresponding one of the venting apertures and oriented to direct air flow. In certain embodiments, the heat-conductive structure defines a plurality of venting apertures adjacent the at least one LED light source, the heat-dissipating surfaces include fins increasing in height at positions adjacent to the at least one of the venting apertures.

FIELD OF THE INVENTION

This invention relates to light fixtures and, more particularly, to light fixtures using light-emitting diodes (LEDs).

BACKGROUND OF THE INVENTION

In recent years, the use of light-emitting diodes (LEDs) in development of light fixtures for various common lighting purposes has increased, and this trend has accelerated as advances have been made in the field. Indeed, lighting applications which previously had typically been served by fixtures using what are known as high-intensity discharge (HID) lamps are now being served by LED light fixtures. Such lighting applications include, among a good many others, roadway lighting, factory lighting, parking lot lighting, and commercial building lighting.

High-luminance light fixtures using LED modules as light source present particularly challenging problems. One particularly challenging problem for high-luminance LED light fixtures relates to heat dissipation. Among the advances in the field are the inventions of U.S. Pat. Nos. 7,686,469 and 8,070,306.

Improvement in dissipating heat to the atmosphere is one significant objective in the field of LED light fixtures. It is of importance for various reasons, one of which relates to extending the useful life of the lighting products. Achieving improvements without expensive additional structure and apparatus is much desired. This is because a major consideration in the development of high-luminance LED light fixtures for various high-volume applications, such as roadway lighting, is controlling product cost even while delivering improved light-fixture performance.

Another challenge is that LEDs produce high temperatures during operation and other fixture portions need to be isolated or insulated for such high temperatures in order to maintain lower operating temperatures permitted for other parts of the fixture.

In summary, finding ways to significantly improve the dissipation of heat to the atmosphere from LED light fixtures would be much desired, particularly in a fixture that is easy and inexpensive to manufacture.

SUMMARY OF THE INVENTION

The present invention relates to improved LED light fixtures. In certain embodiments, the LED light fixture includes first and second fixture portions and at least one LED emitter on an LED heat sink in the first fixture portion. The first and second fixture portions define at least one opening permitting ambient-fluid flow through the fixture. The LED heat sink is open to ambient-fluid flow for removal of heat generated by the at least one LED during operation. The inventive LED light fixture includes at least one barrier structure along the at least one opening to thermally isolate the second fixture portion from the fluid flow heated by the first fixture portion.

The first and second fixture portions at least partially extend along a common plane with the at least one opening permitting ambient-fluid flow through the fixture transverse the common plane.

In certain embodiments of the LED light fixture, the first and second fixture portions are formed as one piece.

In certain embodiments, the second fixture portion forms a substantially closed chamber enclosing power-circuitry unit with permitted operating temperatures lower than operating temperatures of the at least one LED emitter.

The heat sink may include at least one edge-fin transverse to the common plane and extending along the opening away from the at least one LED emitter to a distal edge-fin end. The at least one edge-fin may form the barrier structure.

In some embodiments, the barrier structure is disposed within the at least one opening between the LED heat sink and the second fixture portion to thermally decouple heat sources of the first and second fixture portions.

Certain embodiments of the inventive LED light fixture further include a perforated cover which is in contact with the distal edge-fin end and extending therefrom substantially along the common plane away from the opening. In such embodiments, the cover conductively receives heat from the fins. The perforations of the cover further direct LED-generated heat carried by the fluid flow along the first fixture portion away from the second fixture portion.

In certain embodiments, the heat sink includes a plurality of fins transverse to the common plane and extending away from the at least one LED emitter to distal fin ends. In some of such embodiments, the cover is in thermal contact with the distal fin edges.

The heat sink may have a base with an LED-supporting region and an opposite heat-dissipating region which includes the plurality of fins. In some of such embodiments, the plurality of fins includes at least one edge-fin extending along the opening. At least a subset of the fins may extend substantially parallel to the edge-fin.

The heat sink may further include at least one central venting aperture facilitating ambient-fluid flow to and from a central region of the heat sink. The heat sink may also have at least one peripheral venting aperture along peripheral regions facilitating ambient-fluid flow to and from the heat-dissipating region of the heat sink.

In some of such embodiments, the fins extend farther from the base in the central region than in the peripheral regions. Because the airflow velocity is higher in the center than along the periphery, fins being taller in the center enhances the fin efficiency for the given airflow.

At least some fins of the subset may define horizontal between-fin channels open at the peripheral regions and extending therefrom to the central region.

In certain embodiments, the LED light fixture further includes a peripheral deflector member along each peripheral venting aperture. Each peripheral deflector member may have at least one beveled deflector surface oriented to direct and accelerate air flow from the peripheral venting aperture toward the central region.

In some embodiments, the LED light fixture further includes a central deflector member along the central venting aperture. In some versions, the central deflector member has a pair of oppositely-facing beveled deflector surfaces oriented to direct and accelerate air flow from the central venting aperture toward peripheral regions.

The flow deflectors facilitate effectiveness of the heat-dissipating region and the overall efficiency of heat removal from the entire heat sink for substantially uniform temperatures thereacross.

In another aspect of the present invention, the LED light fixture includes at least one LED light source, which includes at least one LED emitter, and a heat-conductive structure including an LED-supporting region and heat-dissipating surfaces extending away therefrom, the at least one LED light source being thermally coupled to the LED-supporting region. The heat-conductive structure defines venting apertures bordering the at least one LED light source to facilitate ambient fluid flow to and from the heat-dissipating surfaces. The LED light fixture may have a protrusion extending into a corresponding one of the venting apertures and oriented to direct air flow to and along the heat dissipating surfaces.

The protrusion may be part of the heat-conductive structure extending outwardly from the LED-supporting region thereof. In some other embodiments, the protrusion is part of the LED light source and extends outwardly from the at least one LED emitter.

Certain embodiments of the inventive LED light fixture further include a lens member secured to the heat-conductive structure and enclosing the at least one LED light source. The lens member has at least one light-transmissive lens portion and an edge portion extending outwardly therefrom. The edge portion may form the protrusion with a beveled rear surface bordering a corresponding one of the venting apertures and oriented to direct and accelerate air flow from the venting aperture to and along the heat-dissipating surfaces.

Some embodiments of the inventive LED light fixture further include a deflector member along each of the venting apertures. The deflector member has at least one beveled deflector surface angled off-vertical in substantially common direction as the beveled rear surface of the lens member and oriented to accelerate and redirect inwardly upward air flow from the venting aperture toward the heat-dissipating surfaces.

In some of such embodiments, each deflector member is part of the heat-conductive structure. Each deflector member and the heat-conductive structure may be parts of a single-piece structure.

In certain embodiments, the at least one LED light source includes a plurality of spaced apart LED light sources. In such embodiments, the venting apertures may include at least one inner venting aperture between adjacent LED light sources and peripheral venting apertures bordering the LED-mounting region. Each lens member may have at least one edge portion with the beveled rear surface bordering the at least one inner venting aperture.

Certain versions of the inventive LED light fixture may include a peripheral deflector member along each of the peripheral venting apertures. The peripheral deflector member has at least one beveled deflector surface angled off-vertical in substantially common direction as the beveled rear surface of the lens member and oriented to accelerate and redirect inwardly upward air flow from the peripheral venting aperture toward the heat-dissipating surfaces.

Some versions of the inventive LED light fixture may also include an inner deflector along the at least one inner venting aperture. The inner deflector has a pair of oppositely-facing beveled deflector surfaces each angled off-vertical in substantially common direction as the beveled rear surface of the adjacent lens member and oriented to further accelerate and redirect inwardly upward air flow from the peripheral venting aperture toward the heat-dissipating surfaces.

In yet another aspect of the present invention, the LED light fixture includes at least one LED light source and a heat-conductive structure having an LED-supporting region and heat-dissipating fins extending away therefrom. The at least one LED light source is thermally coupled to the LED-supporting region. The heat-conductive structure defines a plurality of venting apertures adjacent the at least one LED light source. The fins increase in height at positions adjacent to the at least one of the venting apertures.

In some of such embodiments, the at least one LED light source includes a plurality of spaced apart LED light sources. The venting apertures include at least one inner venting aperture between adjacent LED light sources and peripheral venting apertures bordering the LED-mounting region. The fins increasing in height at positions adjacent the at least one inner venting aperture.

In certain embodiments, the fins are spanning between the peripheral venting apertures and form between-fin channels across the heat-conductive structure. In such embodiments, the peripheral deflector member is positioned along each peripheral venting aperture to redirect inwardly upward air flow from the peripheral venting aperture to the heat-dissipating fins and along the between-fin channels.

There may be the inner deflector member positioned along the at least one inner venting aperture to redirect inwardly upward air flow from the at least one inner venting aperture to the heat-dissipating fins and along the between-fin channels.

Certain embodiments include a barrier structure dividing the inner venting aperture to separate flow paths corresponding to each of the adjacent LED light sources.

Another aspect of the present invention is the heat-conductive structure defining venting apertures along the at least one LED light source and forming at least one beveled aperture-inlet surface oriented to redirect inwardly upward air flow from the venting aperture to and along the heat-dissipating surfaces.

Some of such embodiments include the lens member secured to the heat-conductive structure and enclosing the at least one LED light source. The lens member has an edge portion having a beveled rear surface bordering a corresponding one of the venting apertures and angled off-vertical in substantially common direction as the beveled aperture-inlet surface of the heat-conductive structure.

In another aspect of the present invention, the LED light fixture includes at the at least one LED light source which has at least one longer side and at least one shorter side. The heat-conductive structure defines venting apertures bordering the at least one longer side of each of said at least one LED light source.

In some embodiments, the at least one LED light source includes a plurality of spaced apart LED light sources each having longer sides and shorter sides. In some of such embodiments, the heat-conductive structure defines a venting aperture bordering said longer sides of said plurality of LED light sources.

The term “ambient fluid” as used herein means air and/or water around and coming into contact with the light fixture.

As used herein in referring to portions of the devices of this invention, the terms “upward,” “upwardly,” “upper,” “downward,” “downwardly,” “lower,” “upper,” “top,” “bottom” and other like terms assume that the light fixture is a position for downward illumination.

In descriptions of this invention, including in the claims below, the terms “comprising,” “including” and “having” (each in their various forms) and the term “with” are each to be understood as being open-ended, rather than limiting, terms.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The figures illustrate exemplary embodiments of LED light fixtures in accordance with this invention. Common or similar parts in different embodiments are given the same numbers in the drawings; the light fixtures themselves are often referred to by the numeral10followed by different letters with respect to alternative embodiments.

FIGS. 1-17 and 27-38illustrate a light fixture10which includes at least one LED light source20and a heat-conductive structure30(also referred hereto as a heat sink) including an LED-supporting region31and heat-dissipating surfaces32extending away therefrom.FIGS. 1, 4, 5 and 27-34illustrate one embodiment of light fixture10A which includes a pair of LED light sources20A each including a plurality of LED emitters21.FIG. 35shows another embodiments of light fixture10B which has a single LED light source20B with a plurality LED emitters21. LED light sources20are thermally coupled to LED-supporting region31. As seen inFIGS. 1, 3-6, 8, 15, 27-32, 35 and 38, the heat-conductive structure30defines venting apertures33bordering LED light sources20to facilitate ambient fluid flow to and from heat-dissipating surfaces32.

FIGS. 6, 11 and 27-32best show LED light fixture10A having a protrusion14extending into a corresponding one of venting apertures33A and oriented to direct air flow to and along heat-dissipating surfaces32.

FIGS. 1, 4 and 27-34show light fixture10A further including a lens member40secured to heat-conductive structure30and enclosing LED light source20. As best seen inFIGS. 1, 4 and 27-34, lens member40has a lens portions41and an edge portion42extending outwardly therefrom.FIGS. 33 and 34show that each light-transmissive part43of lens portion41is aligned with a corresponding one of LED emitters21spaced on a circuit board22.FIGS. 33 and 34also show a safety layer23positioned between lens member40and circuit board22. Features and benefits of safety layer23are disclosed in more detail in U.S. Pat. No. 7,938,558, co-owned with the present application; the entire contents of this patent is incorporated herein by reference.

FIGS. 27-30show edge portion42forming protrusion14with a beveled rear surface44bordering a corresponding one of venting apertures33and oriented to direct and accelerate air flow from such venting aperture33to and along heat-dissipating surfaces32in the form of fins.

FIGS. 6, 8 and 27-30show that fixture10A further includes a deflector member17along each of venting apertures33. Deflector member17has a beveled deflector surface13angled off-vertical in substantially common direction as beveled rear surface44of lens member40and oriented to accelerate and redirect inwardly upward air flow from venting aperture33toward heat-dissipating surfaces32, as seen inFIGS. 6 and 8.

FIGS. 27-30show each deflector member17as part35of heat-conductive structure30. It is best seen inFIG. 27that each deflector member and the heat-conductive structure are parts of a single-piece structure.

LED light fixture10A has a peripheral deflector member35palong each of peripheral venting apertures37. As best seen inFIGS. 29 and 29B, peripheral deflector member35phas a beveled deflector surface38angled off-vertical in substantially common direction as beveled rear surface44of lens member40and oriented to accelerate and redirect inwardly upward air flow from peripheral venting aperture37toward heat-dissipating surfaces32, as seen inFIGS. 6 and 8.

LED light fixture10A also has an inner deflector35ialong inner venting aperture36. As best seen inFIGS. 29 and 29A, inner deflector35ihas a pair of oppositely-facing beveled deflector surfaces38each angled off-vertical in substantially common direction as beveled rear surface44of adjacent lens member40and oriented to further accelerate and redirect inwardly upward air flow from the peripheral venting aperture toward the heat-dissipating surfaces.

FIG. 7shows a comparative illustration of air-flow direction and resulting inferior heat dissipation in a light fixture without deflector members in venting apertures.

FIGS. 1, 4, 33 and 34best show that each of spaced apart LED light sources20A has longer sides25and shorter sides26. Heat-conductive structure30A defines venting apertures33bordering longer sides25of each of LED light sources20A.

FIGS. 35-38illustrate light fixture10B with one LED light source20B including a plurality of spaced LED emitters21. As seen inFIG. 35, fixture10B has cooling ‘ports’ (or vents)33on all four sides of LED light source20B. It is best seen inFIG. 36that fixture10B also has diagonal baffles15to maximize flow of air through fins32and improve effectiveness of fins32B.FIG. 36also shows that fixture10B has a perpendicular fin orientation which helps mix the airflow and increase heat transfer coefficient, as seen inFIG. 38.FIG. 37schematically illustrates a temperature plot showing that, because of effective use of the available surface area, the LED temperature distribution is fairly uniform.

FIGS. 17 and 32show heat conductive structures30including a barrier structure50further dividing inner venting aperture36to separate paths for air flow corresponding to each of the adjacent LED light sources, as illustrated inFIGS. 7, 8 and 11.

FIGS. 11-13, 17 and 18-25illustrate another aspect of this invention showing LED fixture10C having first fixture portion11and second fixture portion12, LED light source20being on an LED heat sink30in first fixture portion11.FIGS. 12, 13 and 18-24show first and second fixture portions11and12defining openings18permitting ambient-fluid flow through fixture10C. It is seen inFIGS. 12 and 13that LED heat sink30is open to ambient-fluid flow for removal of heat generated by LEDs emitters21during operation.FIGS. 12, 13 and 18-24further show that LED light fixture10C includes barrier structure50along opening18to thermally isolate second fixture portion12from the air flow heated by first fixture portion11.

FIG. 26schematically illustrates a prior light fixture without a thermal barrier.FIG. 26shows air flowing through a heat sink and being heated to temperatures that may be in the range of about 85° C. Such “superheated” air comes in contact with a heat-conductive structure forming a chamber for driver-circuitry components. Through such contact, the “superheated” air transfers some of such heat to such chamber-forming heat-conductive structure. This is highly undesirable because operating temperatures of driver-circuitry components should not exceed 65° C. to maintain the longevity of driver-circuitry components similar to the longevity of the LEDs.

FIGS. 12 and 13show first fixture portion11and second fixture portion12at least partially extending along a common plane51with openings18permitting ambient-fluid flow through fixture10C transverse common plane51.

FIGS. 12 and 13also show that heat sink30C has an edge-fin52transverse to common plane51and extending along opening18away from LED emitter21to a distal edge-fin end53. Edge-fin52is shown to form barrier structure50.

FIGS. 12, 13 and 23show a perforated cover60in contact with distal edge-fin end53and extending therefrom substantially along common plane51away from opening18. Perforations61of cover60further direct LED-generated heat carried by the fluid flow along first fixture portion11away from second fixture portion12.

FIGS. 9-13show heat sink30including a plurality of fins32extending away from LED emitters21to distal fin ends54.FIG. 9best show that cover60is in thermal contact with the distal fin edges and conductively receives heat from fins32.

FIGS. 6, 9-13show fins30being taller in a central region70than in peripheral regions71. Because the airflow velocity is higher in the center than along the periphery, fins being taller in the center enhances the fin efficiency for the given airflow.

While the principles of the invention have been shown and described in connection with specific embodiments, it is to be understood that such embodiments are by way of example and are not limiting.