The present disclosure relates to a luminaire and more particularly to a thermally conductive polymer luminaire.
Light fixtures are used in a variety of environments. In lighting applications, such as hazardous environments, reliability of the lighting system is vital. Unfortunately, the characteristics (e.g., humidity, extreme temperatures, corrosive gas) of many environments, including but not limited to hazardous environments, can cause the failure of one or more components of a light fixture to be accelerated. Further, the health and safety of a person located in such an environment can be at risk. When a light fixture is placed in certain environments, such as a hazardous environment, some of these components of a light fixture can pose a safety hazard and a violation of applicable standards if the components are not properly engineered and integrated with the rest of the light fixture.
A thermoplastic polymer must be able to withstand a variety of conditions, especially when utilized in outdoor products. Outdoor electrical products can be in service for 30 or more years and are consistently exposed to extremely harsh environments, such as temperatures ranging from −50° C. to 150° C., with constant exposure to ultraviolet radiation, rain, salt, fog, ozone, thermal cycling, corrosive chemicals, and the like.
In one aspect, a thermally conductive polymer luminaire generally comprises a polymer housing including at least one thermally conductive filler to configure the polymer housing as a thermally conductive polymer housing. The housing includes an inner surface, an outer surface, and a thickness extending between the inner surface and outer surface. The thickness varies along a length of the housing. An electrical component is mounted to the inner surface of the housing opposite a location of the housing having a reduced thickness to facilitate thermal energy release from the housing. A light source is mounted to the housing and electrically connected to the electrical component for emitting light from the housing.
In another aspect, a thermally conductive polymer luminaire generally comprises a polymer housing including at least one thermally conductive filler to configure the polymer housing as a thermally conductive polymer housing. The housing has a longitudinal axis. An electrical board is mounted to an inner surface of the housing. The electrical board has an outer surface defining a plane extending at an angle to horizontal when the longitudinal axis of the housing is oriented parallel to horizontal. A light source is mounted to the electrical board and electrically connected to the electrical board for emitting light from the housing.
In yet another aspect, a thermally conductive polymer luminaire generally comprises a polymer housing including at least one thermally conductive filler to configure the polymer housing as a thermally conductive polymer housing. The housing has a length of less than about 40 inches (101.6 cm), a width of less than about 10 inches (25.4 cm), and a height of less than about 5 inches (12.7 cm). A plurality of electrical components are disposed in the housing whereby an ambient temperature rating of the luminaire is at least about 55° C.
Referring to
A mounting fixture 16 is disposed on a top of the housing 12 for mounting the luminaire 10 in an installation position. For example, for mounting the luminaire 10 such that a longitudinal axis LA of the housing 12 is oriented generally horizontally. Still other installation positions are envisioned. The mounting fixture 16 includes threads 18 for mating with threaded mounting hardware to hang the fixture 10 from a pole or wall or the like. In the illustrated embodiment, the mounting fixture 16 is a pendant mount. However, other mounting fixtures are envisioned without departing from the scope of the disclosure.
A cable feed-through fixture 20 extends longitudinally from the housing 12 and is configured to run electrical power lines into an interior of the housing though an opening 21 in the housing in an explosion-proof manner. A plug 23 closes an opening on an opposite end of the housing 12. Alternatively, cable feed-through fixtures 20 may extend from both longitudinal ends of the housing 12 to run electrical power lines into the housing at one end and out of the housing at the other end. For example, electrical power lines can be run between two adjacent luminaires using the cable feed-through fixtures at their longitudinal ends. Electrical power lines may be run into the housing 12 in other ways without departing from the scope of the disclosure.
Referring to
In one embodiment, the housing 12 comprises a conductive network made by incorporating different types of fillers into a polymer matrix in order to increase the thermal conductivity as well as the mechanical performance of the composite material. In this way, the mechanical performance of the polymer can be maintained without experiencing mechanical degradation as typically occurs when thermally conductive fillers are introduced. Different combinations of filler types can form the conductive network. In order to further improve the thermal conductivity and mechanical performance, nano-fillers can be used to enable formation of conductive networks at lower loadings. Nano-fillers can be provided in different shapes (e.g., spherical, platelet, and rod shape). Thus, the present disclosure generally uses certain nano-fillers, macro-fillers, and fibers in conjunction with a polymer or polymer blend (i.e., polymer matrix) to allow the thermally conductive material to survive in a variety of environments, including harsh and hazardous environments and outdoor, while reducing cost and maintaining desirable mechanical properties. In one embodiment, the housing 12 is formed by injection molding.
In one aspect, the present disclosure is directed to a thermally conductive polymer generally comprising a polymer matrix comprising a polymer or polymer blend, one or more fillers to improve thermal conductivity (thermally conductive filler), one or more fillers to improve tensile strength (tensile strength filler), and one or more fillers to improve impact strength (impact strength filler). Additional fillers can also be incorporated, such as electrically conductive fillers.
In one embodiment, the thermally conductive polymer of the present disclosure has a thermal conductivity of at least about 0.5 W/m*K for example from about 0.5 W/m*K to about 20 W/m*K. For example, in-plane thermal conductivity can be from about 0.5 W/m*K to about 20 W/m*K and through-plane thermal conductivity can be from about 0.5 W/m*K to about 3 W/m*K. Further, the thermally conductive polymer has an impact strength of at least about 7 kJ/m2 for example from about 5 kJ/m2 to about 30 kJ/m2. The thermally conductive polymer also has a tensile strength of at least about 40 MPa, for example from about 40 MPa to about 90 MPa. In various embodiments, the thermally conductive polymer has a volume resistivity of at most about 10 Ω*cm for example from about 1 Ω*cm to about 10 Ω*cm.
The polymer matrix has a high resistance to chemicals and is able to withstand harsh and hazardous environments. In order to achieve ideal properties, a polymer blend may be preferred. Polymer choice can affect a variety of factors of the resulting thermoplastic, such as tensile strength, impact strength, chemical resistance, operating temperature, heat distortion temperature, and the like. Thus, blending different polymers with different desirable characteristics can provide a polymer matrix with a combination of those characteristics.
The polymer matrix can comprise a resin material. The polymer/resin can comprise a thermoplastic material or a thermoset material. In particular, useful polymers include thermoplastic polymers, for example, acrylonitrile butadiene styrene, acrylic, celluloid, cellulose acetate, cyclic olefin copolymer, ethylene-vinyl acetate, ethylene vinyl alcohol, polytetrafluoro ethylene, ionomers, liquid crystal polymer, polyoxymethylene, polyacrylates, polyacrylonitrile, polyamide (e.g., polyamide 66 or polyamide 6), polyamide-imide, polyimide, polyaryletherketone, polybutadiene, polybutylene terephthalate, polycarpolactone, polychlorotrifluoroetyhlene, polyether ether ketone, polyethylene terephthalate, poly-cylcohexylene dimethylene terephthalate, polycarbonate, polyhydroxalkanoates, polyketones, polyester, polyolefin (e.g., polyethylene, polypropylene, polybutylene, and the like) polyetherketoneketone, polyetherimide, polyethersulfone, polysulfone, chlorinated polyethylene, polylactic acid, polymethylmetacrylate, polymethylpentene, polyphenylene, polyphenylene sulfide (PPS), polyphthalamide, polystyrene, polysulfone, polytrimethylene terephthalate, polyurethane, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, styrene-acrylonitrile, or mixtures thereof.
In various embodiments, the base polymer comprises polyphenylene sulfide (PPS) blended with one or more additional polymers. Because PPS is known to create, in some circumstances, a brittle composite, a second polymer can be blended with PPS in order to improve impact properties. For example, PPS can be blended with an elastomer or a polyolefin (such as, for example, polyethylene and/or polypropylene) at relatively low concentrations. Alternatively, in other embodiments, the base polymer comprises a polyketone blended with one or more additional polymers.
The thermally conductive filler can comprise any filler with thermal conductivity known in the art. The filler can have high thermal conductivity (for example, having a thermal conductivity of up to about 900 W/m*K or greater than about 10 W/m*K), an intermediate thermal conductivity (for example, having a thermal conductivity of from about 5 W/m*K to about 10 W/m*K), or a low thermal conductivity (less than about 5 W/m*K). Generally, high thermal conductivity and intermediate thermal conductivity fillers are preferred when used primarily as the thermally conductive filler. When used as the sole thermally conductive filler, high thermal conductivity fillers are most preferred, although intermediate thermal conductivity fillers could also be utilized.
As an example, the thermally conductive filler can comprise carbon black, alumina, boron nitride, silica, carbon fiber, graphene, graphene oxide, graphite (such as, for example, expanded graphite, synthesized graphite, low-temperature expanded graphite, and the like), aluminum nitride, silicon nitride, metal oxide (such as, for example, zinc oxide, magnesium oxide, beryllium oxide, titanium oxide, zirconium oxide, yttrium oxide, and the like), carbon nanotubes, calcium carbonate, talc, mica, wollastonite, clays (including exfoliated clays), metal powders (such as, for example, aluminum, copper, bronze, brass, and the like), or mixtures thereof. For example, the thermally conductive filler can comprise boron nitride, carbon fiber, graphite, carbon nanotubes, or mixtures thereof. In certain embodiments, the thermally conductive filler comprises chopped carbon fibers.
The tensile strength filler can comprise, for example, a macro-size filler and/or a nano-size filler. For example, the macro-size tensile strength filler can comprise carbon fibers. The nano-size tensile strength filler can comprise nano-diamonds, carbon nanotubes, or mixtures thereof. The tensile strength of the filler can be from about 30 MPa to about 100 MPa.
A mixture of nano- and micro-fillers can significantly increase the impact strength of the composite. The nano-size impact strength filler can comprise, for example, carbon nanotubes, clays (including exfoliated clays), other high-aspect ratio fibers, rods, and flakes, spherical nano-particles (including, for example, nano-diamonds, fumed silica, nano-alumina, and fumed alumina), or mixtures thereof. The micro-size impact strength filler can comprise, for example, carbon fiber (for example, chopped carbon fiber, amorphous carbon fiber, long carbon fiber, and the like), alumina, or mixtures thereof. In various embodiments, the impact strength filler comprises chopped carbon fiber, spherical nano-particles, or mixtures thereof.
It may also be desirable to incorporate an electrically conductive filler into the polymer matrix. Electrically conductive fillers include, but are not limited to, carbon fibers, carbon nanotubes, and mixtures thereof. Additional additives can be included to provide modified characteristics, such as UV stability, fire retardancy, heat stabilizers, antioxidants, dyes, pigments, mold release agents, lubricants, adhesion promoters, and the like.
Referring to
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The arrangement of the components within the housing 12 also facilitates reducing the overall size of the housing providing a compact luminaire 10 that maintains satisfactory thermal efficiency for use in hazardous environments. In particular, the electrical boards 30 are canted or angled such that they are not oriented horizontally when the housing 12 is oriented horizontally. Rather, the electrical boards 30 are angled inward such that the LEDs 32 on the boards generally emit light downward and toward a central vertical plane P of the housing 12. In the illustrated embodiment, the electrical boards 30 are oriented such that an outer surface of the electrical boards defines a plane that extends at an angle of about 45 degrees to horizontal. In one embodiment, the electrical boards 30 are oriented such that the outer surface extends at an angle of between about 30 degrees and about 60 degrees to horizontal. Still other angle orientations of the electrical boards are envisioned.
By positioning the electrical boards 30 in this manner, a width W (
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The reflector 70 is mounted in the housing 12 using the second plurality of clips 50B. Therefore, a separate tool (e.g., mechanical driver) is not required to secure the reflector 70 in the housing 12. The second plurality of clips 50B define a pair of slots 74 that receive mounting arms 76 that extend from respective angled surfaces 72 of the reflector 70 to hold the reflector in place in the housing 12. In particular, the second plurality of clips 50B prevent the reflector 70 from moving vertically within the housing 12. The second plurality of clips 50B may also be configured to prevent horizontal movement of the reflector 70. For instance, a notch (not shown) could be formed in the second plurality of clips 50B to prevent or limit horizontal movement of the reflector 70 relative to the housing 12.
In various embodiments, the thermally conductive polymer luminaire of the present disclosure meets certain standards and/or requirements. For example, NEMA sets standards with which an enclosure must comply in order to qualify as an explosion-proof enclosure. Specifically, NEMA Type 7, Type 8, Type 9, and Type 10 enclosures set standards with which an explosion-proof enclosure within a hazardous location must comply. For example, a NEMA Type 7 standard applies to enclosures constructed for indoor use in certain hazardous locations. Hazardous locations may be defined by one or more of a number of authorities, including but not limited to National Electric Code (e.g., Class 1, Division I) and Underwriters' Laboratories, Inc. (UL) (e.g., UL 1203). For example, a Class 1 hazardous area under the National Electric Code is an area in which flammable gases or vapors may be present in the air in sufficient quantities to be explosive.
Examples of hazardous locations in which example embodiments can be used include, but are not limited to, an airplane hangar, an airplane, a drilling rig (as for oil, gas, or water), a production rig (as for oil or gas), a refinery, a chemical plant, a power plant, a mining operation, a steel mill, and the like.
Having described the disclosure in detail, it will be apparent that modifications and variations are possible without departing from the scope of the disclosure defined in the appended claims.
When introducing elements of the present disclosure or the preferred embodiments(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
In view of the above, it will be seen that the several objects of the disclosure are achieved and other advantageous results attained.
As various changes could be made in the compositions without departing from the scope of the disclosure, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.
This application is a continuation of U.S. application Ser. No. 17/145,067, filed Jan. 8, 2021, which claims priority to U.S. Provisional Patent Application Ser. No. 62/959,609, filed Jan. 10, 2020, which is hereby incorporated by reference in its entirety.
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Number | Date | Country | |
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20230003373 A1 | Jan 2023 | US |
Number | Date | Country | |
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62959609 | Jan 2020 | US |
Number | Date | Country | |
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Parent | 17145067 | Jan 2021 | US |
Child | 17930458 | US |