The present invention relates to cooling for lighting fixtures, and particularly, to cooling features to minimize thermal conduction between the light emitter and light driver and maximize thermal convection cooling of the driver.
Managing the temperature of light sources is often important to performance and longevity. This is particularly true with newer highly efficient lighting technology, for example, light sources such as LEDs or laser diodes. LEDs are generally selected to maximize the light output for a given power consumption at a reasonable cost. Because LED light sources operate at a much lower temperature than typical incandescent light sources, less energy is wasted in the form of heat production. However, LEDs tend to be more sensitive to operating temperature and the lower operating temperatures also provide a much smaller temperature difference between the LED and the ambient environment, thus requiring greater attention to thermal management to transfer and dissipate any excess heat generated by the LED driver and emitter so that the design operating temperature for the components are not exceeded.
As temperatures rise, the efficacy of the LED is reduced, reducing the light output. Also, increased operating temperature of the emitter reduces the lifespan of the LED. While the operating temperature is most critical for the LED emitter, the LED driver also generates and is affected by heat. As the temperature rises within a light fixture housing, raising the driver temperature, the lifespan of the driver is adversely affected causing premature failure. Operating at temperatures above the design limits can also cause LEDs to shift in wavelength providing undesirable shifts to the color of the light generated, can damage the LED junction greatly reduce the longevity and performance, and can potentially cause early complete failure of the LED.
To facilitate dissipation of heat, convection, conduction, and radiation are available modes of heat transfer. Thus, it is helpful to provide a light fixture with features that increase the surface area available for convective heat transfer of the heat generated by the LED to the environment around the light housing, for example, features may include cooling fins. Additionally, because more heat is generally generated by the LED emitter than the driver, it is helpful to ensure the heat transferred from the LED emitter is not transferred to the LED driver by conductive heat transfer. However, in most lighting applications, it is also important to maintain a desirable aesthetic appearance to the lighting fixture, and exposure of fins or other such cooling features and separating the emitter and driver into distinct housings tend to provide the light fixture with an undesirable ‘alien’ appearance and, in outdoor applications, promote trapping of debris on or around the cooling fins.
One design seeking to address these concerns provides a set of fins forming vertical airflow channels between a front emitter section and a rear driver section of the light fixture; however, the fins forming the airflow channels vary in length across the light fixture, are in clear view from the sides of the light fixture, and are recessed from the surface of the light fixture, therefore risking the collection of debris in outdoor applications. Thus, in the case of a linear array of emitters, thermal dissipation away from the emitters will vary depending on location relative to the varying sizes of fins. Additionally, the recess formed by the fins may tend to capture debris in outdoor applications. Furthermore, the visibility of the fins from the sides of the light fixture is undesirable.
Therefore, it is desirable to provide a unitary lighting fixture design that minimizes the thermal conduction between the emitter and driver housings, maximizes cooling by thermal convection for the light emitter, shields the cooling features from as many viewing angles as practical, and minimizes the opportunity for debris to be caught in or around the cooling features.
The present invention may comprise one or more of the features recited in the attached claims, and/or one or more of the following features and combinations thereof.
An illustrative light fixture provides a light emitter housing and a light driver housing in a single fixture with an airflow channel defined between the emitter and driver housings. The airflow channel minimizes thermal conduction between the emitter and driver housings, and maximizes thermal convective cooling for at least one of the emitter housing and driver housing. The emitter housing defines vertical fins extending into the airflow chamber. The left and right sides of the emitter and driver housings define top and bottom edges that are respectively coplanar with the top and bottom edges of the vertical fins.
In one illustrative embodiment of a light fixture for a light source having an emitter and driver, an emitter housing defines an emitter mount, the emitter is coupled to the emitter mount, the emitter housing defines a rear surface, a left side, and a right side, and each of the left and right side define a top edge and a bottom edge. The light fixture further includes a driver housing, the driver is coupled to the driver housing, the driver housing defines a front surface, a left side, and a right side, and each of the left and right side define a top edge and a bottom edge.
The light fixture further includes an airflow passage defined by a space between the rear surface of the emitter housing and the front surface of the driver housing and a first plurality of fins located in the airflow passage and defining vertical oriented airflow channels, the vertical oriented airflow channels open to a top side and a bottom side of the fixture, and top and bottom edges are defined by each of the first plurality of fins, and the top edges of the first plurality of fins are coplanar with the top edges of the left side and the right side of each of the driver housing and the emitter housing. At least a portion of each of the first plurality of fins span the space between the emitter housing and the driver housing. The bottom edges of the first plurality of fins can also be coplanar with the bottom edges of the left side and the right side of each of the driver housing and the emitter housing. The rear surface of the emitter housing can define the first plurality of fins, the first plurality of fins are in thermal conductivity with the emitter mount.
In one illustrative embodiment a plane is defined by the top edges of the first plurality of fins and the top edges of the left and right sides of the driver housing and the emitter housing. The plane can be flat, or alternatively, can be curvilinear in a direction from a front of the emitter housing to a back of the driver housing. Additionally, the left sides of the emitter and driver housings can be coplanar; and the right sides of the emitter and driver housings can be coplanar. The first plurality of fins can be evenly spaced. At least one fastener securing the emitter housing to the emitter housing can be fully enclosed by the emitter housing and the driver housing.
In one illustrative embodiment the left sides of the emitter and driver housings enclose a left end of the airflow passage and the right sides of the emitter and driver housings enclose a right end of the airflow passage. In an alternative embodiment, the left sides of the emitter and driver housings define a left side opening of the airflow passage, the left side opening spanning from the top edges of the left sides to the bottom edges of the left sides; and the right sides of the emitter and driver housings define a right side opening of the airflow passage, the right side opening spanning from the top edges of the right sides to the bottom edges of the right sides, and the first plurality of fins are scalloped inward toward the emitter housing along their vertical length, the fins and the driver housing define an open space that extends horizontally between the left side opening and right side opening of the fixture.
In one illustrative embodiment, a second plurality of fins is defined by the driver housing and each of the first plurality of fins is aligned with one of the second plurality of fins. Top edges of the second plurality of fins can be coplanar with the top edges of the first plurality of fins.
In one illustrative embodiment, a top surface is defined by the emitter housing, and the top edges of the first plurality of fins are coplanar with the top surface of the emitter housing. Additionally, or alternatively, a top surface is defined by the driver housing, and the top edges of the first plurality of fins are coplanar with the top surface of the driver housing.
In one illustrative embodiment, at least one of the rear surface of the emitter housing and the front surface of the driver housing extends into the airflow passage.
In another illustrative embodiment, a light fixture for a light source having an emitter and driver, includes an emitter housing defining an emitter mount, the emitter coupled to the emitter mount, the emitter housing defining a rear surface, a left side, a right side, and a top surface; a driver housing, the driver coupled to the driver housing, the driver housing defining a front surface, a left side, and a right side; an airflow passage defined by a space between the rear surface of the emitter housing and the front surface of the driver housing; and a first plurality of fins located in the airflow passage and defining vertical oriented airflow channels, the vertical oriented airflow channels opening to a top side and a bottom side of the fixture, top and bottom edges defined by each of the first plurality of fins; and wherein the top edges of the first plurality of fins are coplanar with the top surface of the emitter housing. At least a portion of each of the first plurality of fins span the space between the emitter housing and the driver housing. The light fixture can further include a second plurality of fins defined by the driver housing, and each of the second plurality of fins are aligned with one of the first plurality of fins. The driver housing can further define a top surface and the top edges of the first plurality of fins are coplanar with the top surface of the driver housing.
Additional features of the disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment.
The detailed description particularly refers to the accompanying figures in which:
For the purposes of promoting and understanding the principals of the invention, reference will now be made to one or more illustrative embodiments illustrated in the drawings and specific language will be used to describe the same.
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The emitter section 50 includes an emitter housing 52, for example, die cast aluminum or an aluminum alloy. The emitter 34 is thermally coupled and mounted to the emitter housing 52. As it typical of commercial lighting fixtures, the emitter section 50 may also include components that enclose the emitter 34 with emitter housing 52, for example, including a light reflector 54, water seal 56, lens 58, and frame and hood 60, and fasteners 62 for securing the frame and hood, lens, water seal, and light reflector to the emitter housing.
The driver section 100 includes a driver housing 102, for example, die cast from aluminum or an aluminum alloy. The driver housing 102 is coupled with the emitter housing 52, for example, with fasteners 108. Thermal insulator 104 may be located between the emitter housing 34 and driver housing 32, for example, either partially, or fully insulating the driver housing from thermal conduction with the emitter housing. As it typical of commercial lighting fixtures, the driver section 100 may also include components that enclose the driver 36 with driver housing 102, for example, including a driver cover 110, water seal 112, and fasteners 114 for securing the water seal and cover to the driver housing. Advantageously, the fasteners 108 can be enclosed within the emitter housing 34, driver housing 32, and driver cover 110, providing a more aesthetically pleasing look to the light fixture 30.
The emitter housing 52 defines one or more emitter mounts 66 on a front surface 68 of the emitter housing. The emitter mounts 66 provide structural mass for increased conduction of heat away from the emitter 36, and also provide relative mounting orientation for the emitter 36. The emitter 36 is coupled to the one or more emitter mounts 66.
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In the first illustrative embodiment 30, where a planar top 42 is defined by a top surface 86 of the emitter housing, and the top edges 96 of the plurality of fins 90 are coplanar with the top surface 86 of the emitter housing. Additionally, the planar top 42 is further defined by a top surface 136 of the driver housing 102, and the top edges 96 of the plurality of fins 90 and the top surface 86 of the emitter housing are also coplanar with the top surface 136 of the driver housing. The top edges 96 of fins 90 being flush with the top surfaces 86 and 136 provides a more aesthetically pleasing appearance, and lessen the likelihood that debris will catch among the interface between the fins 90 and the top surface 86 and 136 since they join and are flush rather than recessed or otherwise non-planar.
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The planes defined by top 42 and bottom 44 can be flat, about flat, for example as in the first illustrative light fixture 30, or curvilinear, for example as shown in the second illustrative light fixture 230, discussed below. Additionally, the left sides 72 and 122 of the emitter and driver housings 52 and 102 can be coplanar, and the right sides 74 and 124 of the emitter and driver housings can be coplanar.
The plurality of fins 90 can be evenly spaced between sides 72 and 74, thus providing equal or about equal sized airflow channels 41. Because the fins 90 are also equal or about equal in length between the top edges 96 and bottom edges 98, the light fixture 30 can provide uniform or about uniform cooling across the span between the sides 72 and 74. Thus, if as in the illustrative light fixture 30, the emitter 34 includes a horizontally arranged array, the emitters 34 can also be spaced to receive equal or about equal conductive and convective cooling from the heat transfer through mounts 66 and fins 90.
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In one illustrative embodiment the left sides of the emitter and driver housings enclose a left end of the airflow passage and the right sides of the emitter and driver housings enclose a right end of the airflow passage.
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The emitter section 250 includes an emitter housing 252, for example, die cast from aluminum or an aluminum alloy. The emitter 234 is thermally coupled and mounted to the emitter housing 252. As it typical of commercial lighting fixtures, the emitter section 250 may also include components that enclose the emitter 234 with emitter housing 252, for example, including a light reflector 254, lens 258, and frame and hood 260.
The driver section 300 includes a driver housing 302, for example, die cast from aluminum or an aluminum alloy. The driver housing 302 is coupled with the emitter housing 352, for example, with fasteners (not shown). As it typical of commercial lighting fixtures, the driver section 300 may also include components that enclose the driver 236 within driver housing 302.
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In a second illustrative light fixture 230, a second plurality of fins 340 is defined by the driver housing 302. Top edges of the second plurality of fins can be coplanar with the top edges of the first plurality of fins.
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In the second illustrative embodiment 230, where a planar top 242 is defined by a top surface 286 of the emitter housing 252, and the top edges 296 of the plurality of fins 290 and the top edges 346 of the plurality of fins 340 are coplanar with the top surface 286 of the emitter housing. The top edges 296, 346 of fins 290, 340 being flush with one another and the top surfaces 286 provides a more aesthetically pleasing appearance, and lessen the likelihood that debris will catch among the interface between the fins 290, 340 and the top surface 286 they join and are flush rather than recessed or otherwise non-planar.
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The planes defined by top 242 and bottom 244 can be flat, about flat, or curvilinear, for example as in the case of the second illustrative light fixture 230. Additionally, the left sides 272 and 322 of the emitter and driver housings 252 and 302 can be coplanar, and the right sides 274 and 324 of the emitter and driver housings can be coplanar.
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Although this invention has been described in certain specific illustrative embodiments, many additional modifications and variations would be apparent to those skilled in the art in light of this disclosure. It is, therefore, understood that this invention may be practiced otherwise than as specifically described. Thus, the illustrative embodiments should be considered in all respects to be illustrative and not restrictive, and the scope of the invention determined by any claims supportable by this application and equivalents thereof, rather than determined solely by the foregoing description.
This is a continuation application of U.S. Nonprovisional patent application Ser. No. 13/611,140, filed Sep. 12, 2012, which is a nonprovisional patent application of U.S. Provisional Patent Application No. 61/533,781, filed Sep. 12, 2011, which are each incorporated herein by reference.
Number | Date | Country | |
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20160178183 A1 | Jun 2016 | US |
Number | Date | Country | |
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61533781 | Sep 2011 | US |
Number | Date | Country | |
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Parent | 13611140 | Sep 2012 | US |
Child | 15054910 | US |