Patent Grant
8602590
The present invention relates to lighting, and more specifically, to light engines and luminaire incorporating one or more active cooling elements.
Solid state light sources offer tremendous advantages over conventional lighting technologies. Of course, some of those advantages come at a cost. One cost of using solid state light sources is that solid state light sources generate heat, sometimes tremendous amounts of heat. Typically, lamps and luminaires that use solid state light sources include thermal management systems, such as but not limited to metal heat sinks. These metal heat sinks are typically large and heavy, including a number of fins to increase surface area and thus dissipate more heat. The larger the heat sink, the more heat that is able to be dissipated, and the more solid state light sources and/or the higher power solid state light sources are able to be used in the lamp or luminaire. Simultaneously, the larger the heat sink, the harder it is to fit the heat sink in a more traditionally sized lamp profile (e.g., a classic A19 Edison light bulb) and/or a more traditionally sized luminaire space (e.g., a six-inch ceiling can).
Alternatives to using a metal heat sink to dissipate heat generated by solid state light sources include thermal management systems based on active cooling elements (e.g., small fans that circulate air through the lamp/luminaire) and thermal management systems based on one or more cooling liquids. In the case of a cooling liquid, the liquid may be passed over or around the solid state light sources, gathering heat, and then, in an active system incorporating a pump or similar device, taken away and cooled, and then returned. Alternatively, the cooling liquid may be heated and evaporated, and then condensed, as in a conventional thermosyphon.
Embodiments described herein provide a new use for a cooling element that incorporates a liquid, such as a thermosyphon. Embodiments described herein provide a thermosyphon light engine that (i) cools one or more solid state light sources, such as but not limited to light emitting diodes (LEDs), organic LEDs (OLEDs), PLEDs, and the like, including combinations thereof, and (ii) helps control and redirect light emitted by the one or more solid state light sources. Further embodiments apply the thermosyphon light engine to luminaires, where the thermosyphon light engine cools not only one or more solid state light sources but also other heat-generating elements of the luminaire (e.g., a power source).
In an embodiment, there is provided a light engine. The light engine includes: a condenser, wherein the condenser returns a gaseous substance located therein to a liquid substance; an evaporation chamber, wherein the evaporation chamber includes: at least one solid state light source that emits light and generates heat upon activation; a working liquid into which at least a portion of the solid state light source is immersed, wherein the working liquid is capable of being changed into a gaseous substance upon the application of heat to the working liquid; and an optical element, wherein the optical element beam shapes light emitted by the at least one solid state light source; and at least one connecting element that joins the condenser to the evaporation chamber, such that when the at least one solid state light source in the evaporation chamber generates heat, a portion of the working liquid evaporates, becoming a gaseous substance, wherein the gaseous substance travels through the at least one connecting element to the condenser, and upon being returned to a liquid substance, wherein the liquid substance travels through the at least one connecting element back to the evaporation chamber.
In a related embodiment, the optical element and the at least one solid state light source may be correspondingly shaped so that the at least one solid state light source rests adjacent to the optical element on an interior surface of the evaporation chamber. In another related embodiment, the evaporation chamber may further include: a support element, wherein the support element may hold the at least one solid state light source in a particular position within the evaporation chamber. In a further related embodiment, the support element may hold the at least one solid state light source in a particular position within the evaporation chamber when the at least one solid state light source is immersed within the working liquid.
In another related embodiment, the evaporation chamber may include a wall, the wall having a first portion and a second portion, wherein the optical element is formed in the first portion of the wall, and wherein the second portion of the wall is shaped to enhance the directional effects of the optical element. In yet another related embodiment, the evaporation chamber may be shaped to include an interior portion and an exterior portion, wherein the interior portion includes the at least one solid state light source, the working liquid, and the optical element, and wherein the exterior portion includes a reflector.
In still another related embodiment, the evaporation chamber may include a plurality of sub-chambers, wherein each sub-chamber in the plurality of sub-chambers may include a solid state light source, a working liquid, and an optical element. In a further related embodiment, each sub-chamber in the plurality of sub-chambers may be shaped to achieve a particular optical effect in combination with the optical element of that sub-chamber. In another further related embodiment, a first sub-chamber in the plurality of sub-chambers may be fixed in a particular direction relative to a second sub-chamber in the plurality of sub-chambers, such that at least a portion of the light beam shaped by the optical element of the first sub-chamber travels in the particular direction. In another further embodiment, the working liquid of a given sub-chamber may be unable to pass into another sub-chamber in liquid form.
In yet still another related embodiment, the light engine may include a plurality of evaporation chambers, wherein the plurality of evaporation chambers may be connected to the condenser by the at least one connecting element. In a further related embodiment, the light engine may include a plurality of condensers, wherein each evaporation chamber in the plurality of evaporation chambers may have a corresponding condenser in the plurality of condensers.
In still yet another related embodiment, the working liquid may have a particular optical characteristic that works in combination with the optical element to beam shape the light emitted by the at least one solid state light source.
In another embodiment, there is provided a luminaire. The luminaire includes: a power source; at least one light source, wherein the at least one light source receives power from the power source; a thermosyphon light engine, including: a condenser, wherein the condenser returns a gaseous substance located therein to a liquid substance; an evaporation chamber, wherein the evaporation chamber includes: at least one solid state light source that emits light and generates heat upon activation; a working liquid into which at least a portion of the solid state light source is immersed, wherein the working liquid is capable of being changed into a gaseous substance upon the application of heat to the working liquid; and an optical element, wherein the optical element beam shapes light emitted by the at least one solid state light source; and at least one connecting element that joins the condenser to the evaporation chamber, such that when the at least one solid state light source in the evaporation chamber generates heat, a portion of the working liquid evaporates, becoming a gaseous substance, wherein the gaseous substance travels through the at least one connecting element to the condenser, and upon being returned to a liquid substance, wherein the liquid substance travels through the at least one connecting element back to the evaporation chamber; a luminaire evaporation chamber including a working liquid; and at least one luminaire connecting element; wherein the working liquid within the luminaire evaporation chamber is heated by heat generated by at least one of the power source and the at least one light source, and wherein the at least one luminaire connecting element connects the luminaire evaporation chamber with the condenser of the thermosyphon light engine.
In a related embodiment, the luminaire may include a plurality of light sources located in relation to the thermosyphon light engine, wherein the luminaire may be shaped such that the condenser and the at least one connecting element of the thermosyphon light engine, and the luminaire evaporation chamber and the at least one luminaire connecting element, are concealed from view. In a further related embodiment, a portion of the evaporation chamber of the thermosyphon light engine that includes at least a portion of the optical element may be visible in relation to the plurality of light sources.
The foregoing and other objects, features and advantages disclosed herein will be apparent from the following description of particular embodiments disclosed herein, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles disclosed herein.
The working liquid 120 within the thermosyphon in some embodiments is, but is not limited to, PF5060 manufactured by 3M®. PF5060 has a low boiling point (56° C. at normal atmospheric pressure) that is critical in maintaining the junction temperature of the at least one solid state light source as low as possible. Alternatively, or additionally, water, various alcohols, various synthetic liquids, and/or combinations of any of these, are used. Indeed, any liquid with a low boiling point (in some embodiments, 60° C. or less) is able to be used as the working liquid 120. The primary consideration in selecting a working liquid 120 depends on how low the junction temperature of the at least one solid state light source is desired to be. The junction temperature of the at least one solid state light source depends on, for example, the substrate used and/or the particular module used that incorporates the at least one solid state light source. The lower bound on the temperature of the working liquid 120 is as close to zero degrees Celsius (i.e., freezing) as possible. In some embodiments, the working liquid 120 may be frozen and then melted by the heat generated by the at least one solid state light source when the solid state light source receives power. Further, in some embodiments, the lower bound on the temperature of the working liquid 120 is substantially 30° C. to control the pressure within the thermosyphon light engine 100.
To serve as a light engine, the evaporation chamber 102 includes an optical element 110. The optical element 110 beam shapes light emitted by the at least one solid state light source located within the evaporation chamber 102. The optical element 110 may be any type of known lens, such as but not limited to a batwing lens, Fresnel lens, and the like. The optical element 110, in some embodiments, is shaped from the material comprising the evaporation chamber. Alternatively, or additionally, the optical element 110 is a separate component that is joined to the evaporation chamber 102, for example but not limited to via a recessed opening or other known connection type.
In some embodiments, it is possible to change the optical element that is used with a particular evaporation chamber 102, by removing the existing optical element and replacing it with a different optical element. In some embodiments, the optical element 110 includes a plurality of optical elements, such as but not limited to any type of lens, including combinations thereof. Though shown in
The evaporation chamber 102 also includes at least one solid state light source, such as but not limited to the LED 112 shown in
The thermosyphon light engine 100 operates as follows. When the at least one solid state light source is activated and begins to emit light, the at least one solid state light source generates heat. The heat causes the working liquid 120 within the evaporation chamber 102 to begin to increase in temperature, until the working liquid 120 begins to boil. As the working liquid 120 boils, some portion of the working liquid 120 is changed into a gaseous substance and/or a substantially gaseous substance. In other words, a portion of the working liquid 120 evaporates. The resulting gaseous substance and/or substantially gaseous substance travels through one of the connecting elements 106, 108 to the condenser 104. The condenser 104 returns the resulting gaseous substance and/or substantially gaseous substance back to a liquid substance (and/or substantially liquid substance) (i.e., the working liquid 120). The liquid substance then travels through the one of the connecting elements 106, 108 back to the evaporation chamber 102. This process runs continually so long as there is heat being generated to cause the working liquid 120 to evaporate, and so long as the evaporation chamber 102 includes enough working liquid 120 to maintain the at least one solid state light source at a particular junction temperature.
In some embodiments, the so-called “back side” of the at least one solid state light source is specially prepared to ensure that the boiling process (i.e., evaporation) begins when the at least one solid state light source receives power, is activated, and begins to generate heat. For example, in some embodiments, one or more channels and/or grooves are scored or otherwise created on the “back side”. Alternatively, or additionally, a sintered material may be used. Alternatively, or additionally, the “back side” may be machine, and/or pre-machined at the time of manufacture, to include one or more grooves and/or channels. Alternatively, or additionally, in some embodiments, a secondary material that is particularly amenable to encouraging and/or enhancing the boiling process may be added. Any additions and/or alterations to the at least one solid state light source that enhance the boiling process (i.e., evaporation) assist in the maintenance of the cooling process performed by the thermosyphon.
In some embodiments, as shown in
Thus, in some embodiments, the evaporation chamber 202 is made from a particular material and/or materials. For example, the evaporation chamber 202 may be made from a material that is clear (i.e., transparent), or translucent, or in some embodiments perhaps even substantially opaque. Whatever material is used should allow light to exit the evaporation chamber 202 through at least the optical element 210. The evaporation chamber 202, in some embodiments, is made entirely of one material (for example but not limited to plastic), and other embodiments, is partially made from a first material and partially made from one or more other materials (e.g., the side walls (i.e., second portion 252A, 252B) could be reflective materials, or a metalized plastic, etc.).
The evaporation chamber 202, in some embodiments, itself is modular, such that it would be possible to swap out one kind and/or shape of evaporation chamber for another. In such embodiments, it is important to have a good seal between the evaporation chamber 202 and any connecting elements (such as connecting elements 106, 108 shown in
In some embodiments, each sub-chamber 402A, 402B, and 402C in the plurality of sub-chambers are of the same and/or substantially the same shape. Alternatively, or additionally, as shown in
As shown in
In some embodiments, the ratio between condensers and solid state light sources (i.e., what is being cooled) may be one to one, and the ratio may be the same between evaporation chambers and what is being cooled. That is, for a single LED module, some embodiments may use a single condenser and a single evaporation chamber. Similarly, for a single LED array, some embodiments may use a single condenser and a single evaporation chamber. Further, in other embodiments, where a number of luminaires including thermosyphon light engine(s) are in a location (e.g., a room), and where each luminaire includes its own LED array/module, the ratio between luminaires and condensers/evaporation chambers may again be 1:1. However, in other embodiments, a higher ratio of light source/elements containing light sources to thermosyphon components may be used.
The thermosyphon light engine 500 shown in
Each evaporation chamber 502A, 502B, and 502C as shown in
The plurality of light sources 660A, 660B are located in relation to the thermosyphon light engine 601. The luminaire 600 is shaped such that the condenser 604 and the connecting elements 606, 608 of the thermosyphon light engine 601, and the luminaire evaporation chamber 676 and the at least one luminaire connecting element 678, are concealed from view. For example, these may be sealed in a housing, such as the housing 679 shown in
When placed into a luminaire, a thermosyphon light engine as described herein may be used as a general illumination source or as accent lighting, or in combinations thereof. This may be done by directly shaping a surface of the luminaire to include one or more protruding thermosyphon light engines. The thermosyphon light engine may also provide cooling to the solid state lighting elements and/or other lighting elements and/or power supply(ies) and/or other heat-generating components associated with the luminaire. In a preferred embodiment, a luminaire is mounted in a ceiling, or otherwise attached thereto, including one or more light sources and one or more thermosyphon light engines. One or more of the light sources may be separate from the one or more thermosyphon light engines, such that the one or more thermosyphon light engines serve as separate light-generating elements from the one or more light sources. For example, the light sources may be a number of pendant fixtures attached to a ceiling tile, which in total is considered to be a luminaire, and the one or more thermosyphon light engines may be embedded within the ceiling tile, and may serve as a general illumination source (along with the pendant fixtures) or as accent lighting. Alternatively, or additionally, the light sources and the thermosyphon light engines may be combined together, such that the thermosyphon light engines include the light sources, and the only source of illumination from the luminaire is the one or more thermosyphon light engines.
Further, the luminaire may receive power in any known way, such as but not limited to via a power source and/or a power supply, whether transmitted to the luminaire via wire or wirelessly, as is known in the art. When the power source, power supply, and/or transmission element(s) is located in some proximity to the luminaire, the power source, power supply, and/or transmission element may be, and in some embodiments, is/are, cooled using a thermosyphon (i.e., evaporation chamber, condenser, and connecting element(s)), either separate from the one or more thermosyphon light engines or otherwise connected thereto.
Alternatively, in some embodiments, instead of the luminaire being a ceiling tile with a number of pendant fixtures and thermosyphon light engines attached thereto, the luminaire itself may include both a traditional luminaire (e.g., a fixture including one or more light sources) and one or more thermosyphon light engines. For example, the luminaire may be a ceiling-mounted fixture, such as but not limited to a flush mounted fixture, where the optical element facing down includes one or more thermosyphon light engines. In some embodiments, the luminaire may be wall mounted instead of ceiling mounted, and the thermosyphon light engines are designed such that the working liquid(s) contained therein remain around the light sources contained therein.
Unless otherwise stated, use of the word “substantial” and/or “substantially” may be construed to include a precise relationship, condition, arrangement, orientation, and/or other characteristic, and deviations thereof as understood by one of ordinary skill in the art, to the extent that such deviations do not materially affect the disclosed methods and systems.
Throughout the entirety of the present disclosure, use of the articles “a” and/or “an” and/or “the” to modify a noun may be understood to be used for convenience and to include one, or more than one, of the modified noun, unless otherwise specifically stated. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
Elements, components, modules, and/or parts thereof that are described and/or otherwise portrayed through the figures to communicate with, be associated with, and/or be based on, something else, may be understood to so communicate, be associated with, and or be based on in a direct and/or indirect manner, unless otherwise stipulated herein.
Although the methods and systems have been described relative to a specific embodiment thereof, they are not so limited. Obviously many modifications and variations may become apparent in light of the above teachings. Many additional changes in the details, materials, and arrangement of parts, herein described and illustrated, may be made by those skilled in the art.
The present application claims priority of U.S. Provisional Patent Application No. 61/330,567, filed May 3, 2010, entitled “Thermosyphon Light Engine” and naming Camil-Daniel Ghiu and Napoli Oza as inventors, the entire contents of which are hereby incorporated by reference.
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