Patent Grant
8579476
The present disclosure relates generally to the thermal management of illumination devices, and more particularly to the thermal management of LED-based illumination devices through the use of synthetic jet ejectors.
A variety of thermal management devices are known to the art, including conventional fan based systems, piezoelectric systems, and synthetic jet ejectors. The latter type of system has emerged as a highly efficient and versatile solution where thermal management is required at the local level. Frequently, synthetic jet ejectors are utilized in conjunction with a conventional fan based system. In such hybrid systems, the fan based system provides a global flow of fluid through the device being cooled, while the synthetic jet ejectors provide localized cooling for hot spots, and also augment the global flow of fluid within the device through the perturbation of boundary layers.
Various examples of synthetic jet ejectors are known to the art. Some examples include those disclosed in U.S. 20070141453 (Mahalingam et al.) entitled “Thermal Management of Batteries using Synthetic Jets”; U.S. 20070127210 (Mahalingam et al.), entitled “Thermal Management System for Distributed Heat Sources”; 20070119575 (Glezer et al.), entitled “Synthetic Jet Heat Pipe Thermal Management System”; 20070119573 (Mahalingam et al.), entitled “Synthetic Jet Ejector for the Thermal Management of PCI Cards”; 20070096118 (Mahalingam et al.), entitled “Synthetic Jet Cooling System for LED Module”; 20070081027 (Beltran et al.), entitled “Acoustic Resonator for Synthetic Jet Generation for Thermal Management”; and 20070023169 (Mahalingam et al.), entitled “Synthetic Jet Ejector for Augmentation of Pumped Liquid Loop Cooling and Enhancement of Pool and Flow Boiling”.
The devices and methodologies disclosed herein may be further understood with reference to the particular, non-limiting embodiments of the illumination devices depicted in
The light emitting portion 101 in this embodiment houses a pedestal 125 (see
The light emitting portion 201 in this embodiment contains a synthetic jet actuator housing 211 which contains a set of diaphragms 213, and upon an exterior surface of which are disposed a plurality of LEDs 215. The set of diaphragms 213 operate to generate a plurality of synthetic jets 217, which are emitted from a plurality of apertures (not shown) provided in the synthetic jet actuator housing 211, and which transfer heat from the LEDs 215 to the interior of the light emitting portion 203. The apertures may be disposed in a variety of suitable patterns around one or more of the LEDs 215, one particular example of which is depicted in
The embodiment of
The connector module 305 in this embodiment contains a synthetic jet actuator 307 which is equipped with a set of diaphragms 313. The synthetic jet actuator 307 is in fluidic communication with a pedestal 325 which is equipped on one end with a plenum 312. The plenum 312 is equipped with a plurality of apertures 320, and has a plurality of LEDs 315 disposed on an exterior surface thereof. The set of diaphragms 313 operate to generate a plurality of synthetic jets 317, which are emitted from a plurality of apertures 320 provided in the plenum 312, and which transfer heat from the LEDs 315 to the interior of the light emitting portion 303. The apertures 320 may be disposed in a variety of suitable patterns around one or more of the LEDs 315. The heat in the interior of the light emitting portion 303 may then be transferred to the external environment through thermal conduction, through the provision of apertures or vents in the light emitting portion 303, or by other suitable means.
The embodiment of
This embodiment is similar to the embodiment of
The illumination device 501 in this embodiment is a hybrid of the embodiments depicted in
The illumination device 501 in this embodiment is also equipped with a vent 523 which allows the atmosphere inside of the light emitting portion 503 to be in fluidic communication with the external atmosphere. In some variations of this embodiment, the synthetic jet ejector 509 may be adapted to emit synthetic jets from apertures in the vent 523, either solely or in addition to emitting synthetic jets 517 from the actuator housing 511.
The illumination device 601 in this embodiment is similar in many respects to the illumination device 501 of
The light emitting portion 703 in this embodiment contains an active diaphragm 733 and a passive diaphragm 735 which are in fluidic communication with each other. A heat sink 759 comprising at least one heat fin 727 is disposed between the active diaphragm 733 and the passive diaphragm 735 and has a plurality of LEDs 715 disposed thereon. Each heat fin 727 has at least one channel 737 defined therein which is in fluidic communication with the environment external to the light emitting portion.
In operation, the active diaphragm 733 vibrates to produce a plurality of synthetic jets 717 in the air passing through the channels 737 and into the external environment. Hence, as the heat fins 727 absorb heat from the LEDs 715 mounted on the heat sink 759, this operation ensures that the heat is efficiently transferred to the external environment through the turbulent flow created by the synthetic jets 717. During operation, the larger passive diaphragm 735 basically serves as a counterweight to the active diaphragm 733, which allows the synthetic jet actuator 709 to provide sufficient heat flux while operating outside of the audible range and producing fewer vibrations.
The passive diaphragm 735 preferably has the same mass as the active diaphragm 733, although the dimensions of the two diaphragms may be the same or different. The passive diaphragm 735 may also be of the same or different construction as the active diaphragm 733. In some implementations of the embodiment, the passive diaphragm 735 may comprise a transparent or translucent material.
The illumination device 801 in this embodiment is equipped with a combination synthetic jet ejector/heat sink 829 which contains both a synthetic jet ejector 809 and a heat sink 827. These two components may be combined in a variety of ways, and each of these components, or the combination thereof, may have a variety of shapes or sizes. The two components may also comprise a variety of materials, though the heat sink 827 preferably comprises a thermally conductive material such as a metal (such as, for example, copper, aluminum, tin, steel, or various combinations or alloys thereof) or a thermally conductive loaded polymer. In the particular embodiment depicted, however, the heat sink 827 extends from one side of the synthetic jet ejector 809 and is adapted to direct synthetic jets 817 through channels 837 defined in the heat sink 827. Since the LED 815 is mounted on top of the heat sink 827 and is in thermal communication therewith, this arrangement transfers heat from the LED 815 to the atmosphere external to the illumination device 801.
In the embodiment depicted in
The illumination device 901 of this embodiment is similar in most respects to the illumination device 801 of
In this embodiment, a heat sink 1059 is disposed about the exterior of the light emitting portion 1003 and the synthetic jet ejector 1009 is disposed within the light emitting portion 1003. However, the synthetic jet ejector 1009 is in fluidic communication with the heat sink 1059 by way of one or more channels 1037. In the particular embodiment depicted, these channels 1037 extend from the interior of the light emitting portion to the exterior of the light emitting portion 1003, and are adapted to direct one or more synthetic jets across the surfaces of the heat sink 1059 or the heat fins 1027 thereof.
The illumination device 1101 of this embodiment is similar in most respects to the illumination device 901 of
This embodiment illustrates the application of the principles described herein to a popular type of compact fluorescent light bulb. The synthetic jet actuator 11207 in this embodiment is equipped with a set of nozzles 1241 which are adapted to direct a plurality of synthetic jets 1217 across the surfaces, or into the interior of, the helical coil of the light emitting portion 1203. The nozzles 1241 are in fluidic communication with the interior of the synthetic jet actuator 1207 where the diaphragms 1213 are disposed, and the LEDs 1215 which illuminate the light emitting portion 1203 are disposed in, or adjacent to, this fluidic path.
In operation, the synthetic jet actuator 1207 operates to create a fluidic flow adjacent to, or across the surfaces of, the LEDs 1215, thereby removing heat from the LEDs and rejecting it to the external environment. The hot fluid is ejected as a synthetic jet 1217, and hence is removed a significant distance from the nozzles 1241. The synthetic jets also entrain cool air from the local environment and create a turbulent flow around the surfaces of the helix of the light emitting portion, thus helping to cool this portion of the illumination device 1201 as well. The synthetic jets also draw in cool fluid around the nozzles 1241, which is then drawn into the synthetic jet ejector during the in-flow phase of the diaphragms 1213.
The illumination device of
Various modifications may be made to the embodiment depicted in
The illumination device 1401 of
In some variations of this embodiment, the helical coils of the light emitting portion 1403 may comprise a suitably thermally conductive material. Such a material may provide for more efficient transfer of heat from the LEDs 1439 to the underlying substrate, where it may be rejected to the external atmosphere by the fluidic flow created by the synthetic jet actuator 1407. In other variations, the LEDs 1439 may be directed inward so that their backsides are exposed to the internal environment, and their light emitting surfaces are directed towards the interior of the helical coil. In these different embodiments, a metallic interconnect may be disposed on the interior or exterior surface of the coils, or may be embedded in the walls of the coils.
In this embodiment, the synthetic jet actuator 1507 is centrally disposed within the light emitting portion 1503, and a plurality of LEDs 1515 are disposed around it. A heat sink 1559 is built into the base of the illumination device 1501, and is equipped with channels 1537 which are in fluidic communication with the synthetic jet actuator 1507. During operation, the synthetic jet actuator 1507 creates a fluidic flow which preferably includes synthetic jets 1517, and which rejects heat from the heat sink 1559 to the external environment.
As indicated in
One wall of the synthetic jet ejector 1609 is equipped with a heat sink 1659 comprising a plurality of heat fins 1627. The heat fins 1627 are disposed adjacent to an LED 1615 and define a plurality of channels 1637 which are in fluidic communication with the interior of the synthetic jet ejector 1609.
During operation, the heat sink 1659 absorbs heat from the LEDs 1615, and the synthetic jet ejector 1609 generates a plurality of synthetic jets 1617 in the channels 1637 which transfers the heat to the interior environment of the light emitting portion 1603. From there, the heat is rejected to the external environment through thermal transfer. In some implementations, thermal transfer to the external environment may be facilitated by the provision of suitable venting in the light emitting portion 1603 or by other suitable means. As with the previous embodiment, the design of this illumination device 1601 allows for the use of relatively large diaphragms 1613 in the synthetic jet ejector 1609, which may be useful in achieving high heat flux from the heat sink 1659 to the external environment.
In this embodiment, the synthetic jet ejector 1709 is centrally disposed within a heat sink 1759 having a plurality of external heat fins 1727. The external heat fins 1727 have a plurality of channels 1737 defined therein which are in fluidic communication with the interior of the synthetic jet ejector 1709 and the external environment. An LED 1715 is disposed on top of the heat sink.
In operation, the heat sink 1759 absorbs heat given off by the LED 1715, and this heat is transferred to the heat fins 1727. The synthetic jet ejector 1709 creates a plurality of synthetic jets 1717 in the channels 1737 which rejects the heat to the external environment. As with the previous embodiment, the design of this illumination device 1701 allows for the use of relatively large diaphragms 1713 in the synthetic jet ejector 1709, which may be useful in achieving high heat flux from the heat sink 1759 to the external environment.
In this embodiment, the synthetic jet ejector 1809 is centrally disposed within a heat sink 1859 having a plurality of external heat fins 1827. The portion of the heat sink 1859 which separates the light emitting portion 1803 from the heat fins 1827 is porous, and hence provides for fluidic flow between the interior of the light emitting portion 1803 and the external environment as indicated by arrows 1863. This may be achieved, for example, by forming this portion of the heat sink 1859 out of a foamed, thermally conductive material, such as a foamed metal, or by providing a plurality of apertures or vents in this portion of the heat sink 1859. An LED 1815 is disposed on top of the heat sink 1859.
Similarly, the interior of the light emitting portion 1803 is in fluidic communication with the interior of the synthetic jet ejector 1809. This may be accomplished, for example, by seating the LED 1815 on a metal plate or heat spreader which is in thermal contact with the heat fins 1827, and which has a plurality of apertures 1837 therein adjacent to the LED 1815 which are in fluidic communication with the interior of the synthetic jet ejector 1809.
In operation, the heat sink 1859 absorbs heat given off by the LED 1815, and this heat is transferred to the heat fins 1847. The synthetic jet ejector 1809 emits a plurality of synthetic jets 1817 from the channels 1837, which in turn creates a flow of fluid across the heat fins 1827. The synthetic jets 1817 also facilitate the transfer of heat from the LED 1815 to the interior atmosphere of the light emitting portion 1803, where the warmed fluid can then exit the light emitting portion 1803 to the external environment as indicated by the arrows 1863. This fluidic flow also facilitates the transfer of heat from the heat fins 1827 to the external environment. As with the previous embodiment, the design of this illumination device 1801 allows for the use of relatively large diaphragms 1813 in the synthetic jet ejector 1809, which may be useful in achieving high heat flux from the heat sink 1859 to the external environment.
The illumination device 1901 in this embodiment is equipped with a heat sink 1959 comprising a plurality of heat fins 1927, and upon which is disposed an LED 1915. The illumination device 1901 comprises an interior housing element 1955 and an exterior housing element 1957 which, between them, define a channel 1937 for fluidic flow. The channel 1937 is in fluidic communication with the synthetic jet actuator 1907 by way of a series of internal apertures 1909, and is further in fluidic communication with a plurality of nozzles 1941 disposed about the interior of the light emitting portion 1903.
In operation, the synthetic jet actuator 1907, which is driven by one or more diaphragms 1913, creates a plurality of synthetic jets 1917 at the nozzles 1941. The synthetic jets 1917 are directed at, or across, the surfaces of the LED 1915, and especially the light emitting surface thereon. The synthetic jets 1917 facilitate the transfer of heat from the LED 1915 to the interior atmosphere of the light emitting portion 1903, where it can be dissipated through thermal transfer to the internal 1955 and external 1957 housing elements and to the external environment, or through absorption by the heat sink 1959. The heat sink 1959 serves to absorb heat directly from the backside of the LED 1915. In some implementations of this embodiment, the heat sink 1959 may be equipped with one or more heat pipes.
In operation, the light emitted from the LEDs 2015 is reflected off of the reflective surface 2045 and is emitted through the exterior wall of the light emitting portion 2003. The degree of specular or diffuse reflectivity of these two surfaces may be selected to achieve a desired illumination footprint. Heat is withdrawn from the LEDs 2015 by the heat sink 2059. The synthetic jet ejector 2009 creates a fluidic flow across the surfaces of the heat fins 2027 as indicated by the arrows 2063, thus rejecting the heat to the external environment. Preferably, this flow 2063 is in the form of one or more synthetic jets.
In use, the synthetic jet ejector 2109 creates a plurality of synthetic jets 2117 in the vicinity of the LED 2115. The synthetic jets impinge on the surface of the depression 2151, and thus aid in the transfer of heat from the interior of the light emitting portion 2103 to the external environment.
In operation, the synthetic jet ejector 2209 creates a fluidic flow about the LEDs 2215 in the form of one or more synthetic jets 2217. This flow transfers heat from the LEDs 2213 to the surfaces of the tubing 2257 of the light emitting portion 2203, where it is rejected to the external atmosphere.
In operation, the synthetic jet ejector 2309 creates a fluidic flow about the LEDs 2315 in the form of one or more synthetic jets 2317. This flow transfers heat from the LEDs 2315 to the surfaces of the tubing 2357 of the light emitting portion 2303, where it is rejected to the external atmosphere.
In operation, the synthetic jet ejector 2409 creates a fluidic flow about the LEDs 2415 in the form of one or more synthetic jets 2417. This flow transfers heat from the LEDs 2415 to the surfaces of the tubing 2457 of the light emitting portion 2403, where it is rejected to the external atmosphere. The external vent 2423 provides an additional means by which heat may be rejected to the external environment.
In some variations of this embodiment, the illumination device 2401 may be adapted to emit synthetic jets from the external vent 2423. In other variations, the synthetic jet ejector provides a fluidic flow around the LEDs 2415, but only emits synthetic jets at the external vent 2423.
Reflective Materials
The various embodiments of light fixtures disclosed herein may be equipped with various reflective materials or surfaces. These include, without limitation, specularly or diffusely reflective or scattering materials. Such materials may be applied to the intended substrate as coatings or films. In some implementations, these coatings or films may be formed and then applied to the substrate, while in other implementations, they may be formed on the substrate in situ.
Examples of such scattering films include those based on continuous/disperse phase materials. Such films may be formed, for example, from a disperse phase of polymeric particles disposed within a continuous polymeric matrix. In some embodiments, one or both of the continuous and disperse phases may be birefringent. Such a film may be oriented, typically by stretching, in one or more directions. The size and shape of the disperse phase particles, the volume fraction of the disperse phase, the film thickness, and the amount of orientation may be chosen to attain a desired degree of diffuse reflection and total transmission of electromagnetic radiation of a desired wavelength in the resulting film. Films of this type, and methods for making them, are described, for example, in U.S. Pat. No. 6,031,665 (Carlson et al.), which is incorporated herein by reference in its entirety. Analogous films in which the disperse phase comprises inorganic or non-polymeric materials (such as, for example, silica, alumina, or metal particles) may also be utilized in the devices and methodologies described herein.
Reflective surfaces may also be imparted to the devices described herein through suitable metallization. These include, for example, films of silver or other metals which may be formed through vapor or electrochemical deposition.
Electrical Outlets
The various embodiments of light fixtures disclosed herein may be equipped with various electrical connectors. These include, without limitation, threaded connectors that rotatingly engage complimentary shaped sockets in an electrical outlet; prong connectors, which may be male or female, and which mate with complimentary shaped prongs or receptacles in an electrical outlet; cord connectors; and the like. The choice of connector may vary from one application to another and may depend, for example, on the wattage output of the light fixture and other such considerations as are known to the art. It will be understood, however, that while embodiments of light fixtures may have been disclosed or illustrated herein as having a particular connector type, any other suitable connector, including those described above, may be substituted where suitable for a particular application.
Bulb Coatings/Pigments
The various embodiments of light fixtures disclosed herein may be equipped with various bulbs. These bulbs, or any portion thereof, may be clear, opaque, specularly or diffusively transmissive, specularly or diffusively reflective, polarizing, mirrored, colored, or any combination of the foregoing. In some embodiments, the bulb may also be equipped with a film or pigment which provides the light fixture with a desired optical footprint. These bulbs may also be equipped with any of the various types of phosphors as are known to the art, or with various combinations of such phosphors.
Synthetic Jet Actuators/Ejectors
Various synthetic jet actuators and synthetic jet ejectors may be utilized in the devices and methodologies described herein. Preferably, however, the synthetic jet actuators and synthetic jet ejectors are of the type described in U.S. Ser. No. 61/304427, entitled “SYNTHETIC JET EJECTOR AND DESIGN THEREOF TO FACILITATE MASS PRODUCTION” (Grimm et al.), which is incorporated herein by reference in its entirety. These synthetic jet actuators and synthetic jet ejectors may have various sizes, dimensions and geometries, and hence may be adapted to spaces available in the host device. Hence, for example, the synthetic jet ejector may be cylindrical, parallelepiped, or irregular in shape.
As best seen in
Notably, in the particular illumination device 2501 depicted, elements of the host illumination device 2501 define the housing of the synthetic jet ejector 2509. Consequently, the overall space occupied by the synthetic jet ejector 2509 is significantly reduced compared to the situation that would exist if the synthetic jet ejector was made as a standalone unit (with its own housing) and subsequently incorporated into the host device. Moreover, in this embodiment, the upper wall 2575 (see
Heat Sinks
The various illumination devices described herein may be equipped with heat sources of various sizes, shapes and geometries. These heat sinks may be readily adapted to the space available within the illumination device or external to it. In some embodiments, these heat sinks may comprise a plurality of heat fins.
In some applications, it may be desirable to mount the heat sink on the exterior of a illumination device. Examples of such embodiments may be found in
The above description of the present invention is illustrative, and is not intended to be limiting. It will thus be appreciated that various additions, substitutions and modifications may be made to the above described embodiments without departing from the scope of the present invention. Accordingly, the scope of the present invention should be construed in reference to the appended claims.
The present application is a continuation-in-part of U.S. Ser. No. 12/503,181, entitled “THERMAL MANAGEMENT OF LED-BASED ILLUMINATION DEVICES WITH SYNTHETIC JET EJECTORS” (Heffington et al.), filed on Jul. 15, 2009, now abandoned and which is incorporated herein by reference in its entirety, and which claims priority to U.S. Ser. No. 61/134,984, entitled “THERMAL MANAGEMENT OF LED-BASED ILLUMINATION DEVICES WITH SYNTHETIC JET EJECTORS” (Heffington et al.), filed on Jul. 15, 2008, and which is incorporated herein by reference in its entirety.
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| 5758823 | Glezer et al. | Jun 1998 | A |
| 7401945 | Zhang | Jul 2008 | B2 |
| 7568817 | Lee et al. | Aug 2009 | B2 |
| 7637636 | Zheng et al. | Dec 2009 | B2 |
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| 8317358 | Chou | Nov 2012 | B2 |
| Number | Date | Country | |
|---|---|---|---|
| 20110089804 A1 | Apr 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61134984 | Jul 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12503181 | Jul 2009 | US |
| Child | 12902295 | US |
