Light fixture comprising carbon materials and methods therefor
10801702 ยท 2020-10-13
Inventors
Cpc classification
F21V17/12
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V29/503
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V27/02
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21Y2115/10
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V31/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V23/001
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V15/01
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V29/87
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V19/0055
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21W2131/103
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V29/85
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21Y2105/16
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21S8/086
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21W2131/40
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F21V17/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21S8/08
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V19/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A light fixture may include a dome member including exterior and interior surfaces, and a panel positioned adjacent to the interior surface of the dome member. The panel may comprise carbon fiber. The panel may provide a mounting surface to which circuit boards including LEDs are mountable. The panel may include raised portions and recessed portions, which provide a mounting surface to which the circuit board(s) may be mounted. The circuit board may span the distance between adjacent raised portions of the panel, spanning a corresponding recess. Such a recess may provide for an air gap for improved air circulation. The fixtures may be used in corrosive environments, to provide a useful life that is extended relative to what the lifespan would be if the panel were not carbon fiber. Examples of corrosive environments include livestock facilities, enclosed agricultural facilities, coastal highways, sewage and other water treatment plants, etc.
Claims
1. A method of providing degradation-resistant light fixtures in a corrosive environment, the method comprising: providing one or more LED light fixtures in the corrosive environment, each light fixture comprising: a dome member including an exterior surface and an interior surface; and a panel attached to the interior surface of the dome member, wherein the panel comprises carbon fiber; the panel including raised portions and recessed portions between adjacent raised portions, the raised portions including a mounting surface; at least one circuit board mounted to the mounting surfaces so that the circuit board spans between the adjacent raised portions of the panel, the at least one circuit board including one or more LEDs; wherein the carbon panel of the light fixture resists degradation from corrosive components present in the corrosive environment such that the light fixture has a useful life that is extended relative to what the useful life would be were the panel not comprised of carbon fiber.
2. The method as recited in claim 1, wherein both the dome member and the panel both comprise carbon fiber.
3. The method as recited in claim 1, wherein the corrosive environment is a coastal highway, sewage treatment plant, municipal water treatment plant, or an enclosed agricultural production facility.
4. The method as recited in claim 1, wherein the method further comprises mounting or providing the light fixture mounted on a pole support, wherein the pole support of the light fixture also comprises carbon fiber.
5. The method as recited in claim 4, wherein the pole support is formed from a composite comprising the carbon fiber and fiberglass, in a matrix material.
6. The method as recited in claim 5, wherein the matrix material comprises an epoxy or other resin or polymeric matrix material within which the carbon fiber and fiberglass materials are embedded.
7. A lightweight degradation resistant light fixture and associated support, comprising: a light fixture comprising: a dome member including an exterior surface and an interior surface; and a panel positioned adjacent to the interior surface of the dome member, wherein the panel is formed from carbon fiber; wherein the panel includes raised and recessed portions, the raised portions providing a mounting surface for mounting a circuit board of an LED light source thereto; a support comprising a vertical pole on which the light fixture is supported, wherein the vertical pole of the support also comprises carbon fiber.
8. The light fixture and support as recited in claim 7, further comprising: a lens cover disposed over the panel to protect one or more circuit boards mounted to the panel; a space between the interior surface of the dome member and the panel; and an access door through the exterior surface of the dome member for accessing the space between the dome member and the panel.
9. The light fixture and support as recited in claim 7, wherein both the dome member and the panel are formed from carbon fiber.
10. The light fixture and support as recited in claim 7, wherein the vertical pole is formed from a composite of the carbon fiber, fiberglass, and a matrix material.
11. The light fixture and support as recited in claim 10, wherein the matrix material comprises epoxy or another resin material, or a polymeric matrix material.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) In order that the manner in which the above-recited and other advantages and objects of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings.
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS
I. Introduction
(14) Embodiments of the disclosure relate to light fixtures, particularly light fixtures in which a panel of the light fixture to which circuit boards including the light source (e.g., LEDs or other high efficiency light source) are mounted, wherein the panel comprises carbon fiber or other carbon material exhibiting a relatively high thermal conductivity. For example, carbon fiber may have thermal conductivity that varies depending on specific compositional, geometric (fiber size, orientation, etc.) and other characteristics, although in any such case, the carbon fiber may have a thermal conductivity of at least about 20 W/mK, at least about 50 W/mK, at least about 75 W/mK, or at least about 100 W/mK. Other forms of carbon having similarly high thermal conductivity could alternatively be used (e.g., amorphous carbon, graphene, or graphite). Other carbon containing materials (e.g., plastics such as polycarbonate or the like), while technically containing carbon, provide nowhere near such high values of thermal conductivity, nor do they provide similar resistance to corrosion of such materials that approach a composition consisting essentially of carbon (e.g., carbon fiber, amorphous carbon, graphene, or graphite). For example, carbon fiber is typically formed from a polyaromatic hydrocarbon (pitch resin), or polyacrylonitrile (PAN) processed carbon, and includes high fractions of carbon in the composition, as well as a typical aromatic or graphene ring structure.
(15) While orientation of carbon fiber in a composite can affect the thermal conductivity (e.g., conduction can often be higher along the longitudinal axis of the fiber, and lower in directions transverse to the fiber orientation), there is sufficient thermal conductivity to such carbon fiber that fiber orientation may generally be unimportant in dissipating heat away from the heat generated by the LEDs on the circuit boards, the presently contemplated embodiments. Of course, specific orientations of the fibers may be provided, to increase thermal conductivity away from the circuit boards, or for other reasons (e.g., structural strength characteristics in the panel and/or the dome).
(16) In addition to thermal conductivity benefits, the use of such forms of carbon within the panel is also advantageous as such forms of carbon are a relatively chemically inert, stable material under contemplated usage conditions. For example, as described above, in dairy barn and similar agricultural livestock operations, there is a significant and enduring concentration of reactive or corrosive components which degrade typical and existing lighting fixtures used in such environments. In addition to the methane (CH.sub.4) present in such environments, there are also significant concentrations of sulfur containing corrosive compounds, and/or nitrogen containing corrosive compounds, which can react with and degrade the materials (such as metals and plastics) typically used in existing lighting fixtures. H.sub.2S is believed to be one such constituent present in at least some of the contemplated use environments. While the mechanisms relative to inertness and stability may not be fully understood, the inventor has found that the presently described light fixtures are advantageously resistant to the rotting and other degradation that routinely occurs in light fixtures employed in dairy barns and similar environments, so as to provide a very real benefit in that the light fixtures last far longer than the typical 2-3 years seen with existing alternatives. This can be particularly advantageous in livestock operations conducted in an enclosed building (e.g., with a roof and walls, even though some ventilation may be present), where such corrosive gases or other materials may tend to be present in elevated, chronic concentrations that lead to such rotting.
(17) Similar advantages can be provided in other corrosive environments, e.g., including, but not limited to lighting along coastal highways, lighting along other coastal locations where airborne and other salinity levels are similarly elevated, sewage and municipal water treatment plants, enclosed agricultural production facilities other than dairy or other livestock barns (e.g., facilities for growing plants, where humidity and various salinity concentrations (e.g., calcium salts) are elevated. For example, grow lights are typically used for growth of such plants indoors, in a closed close quarters type environment, where humidity is typically elevated (e.g., greater than 50% relative humidity (RH), greater than 55%, greater than 60%, greater than 65%, greater than 70%, greater than 75%, greater than 80%, or greater than 85% RH, such as 55-99% RH, 60-99% RH, 80-99% RH, or the like). Time of wetness (TOW) in such an environment may approach, or be, 100% (e.g., every day within a year, RH is over 50%).
(18) In addition, in such conditions, salts other than NaCl, such as calcium or other salts tend to build up deposits or scale on existing light fixtures. Such salts may similarly cause or exacerbate corrosion. Within any of such, or other similar corrosive environments, accelerated degradation of the fixtures and associated supporting structure continues to be a problem. Other environments where corrosion of existing lighting fixtures is accelerated will be apparent to those of skill in the art, in light of the present disclosure. For example, within any such environment, the carbon panel of the present light fixture may resist degradation from any of various corrosive components present in the corrosive environment, such that the light fixture has a useful life that is extended relative to what the useful life would be were the panel not comprised of carbon fiber. In may lighting applications, the light fixture may be supported on a support, e.g., such as a vertical or other oriented pole. Such poles are often formed from galvanized steel, which exhibits accelerated corrosion under environments such as those described herein (e.g., along a coastal highway). In an embodiment, additional benefit may be achieved by forming the pole or other support from carbon fiber or similar material, as well. Such a pole or other support would significantly reduce the weight of the resulting assembly (light fixture and support pole), while at the same time providing the support or any other component formed from carbon fiber or the like with increased degradation resistance.
II. Exemplary Light Fixtures
(19)
(20) Such a configuration allows heat generated by LEDs 112 (or another high efficiency light source) to be drawn away from LEDs 112, into board 106, and then quickly and efficiently drawn from board 106 into raised portions 110, and then into the remainder of panel 104 as a result of the relatively high thermal conductivity provided by carbon fiber or similar carbon material from which panel 104 is fabricated. As described above, the panel may comprise a material, such as carbon fiber, having a thermal conductivity that is comparable to or greater than that provided by conventional metal materials from which a light fixture may otherwise be manufactured. For example, many steels have a thermal conductivity within a range of about 15 to about 30 W/mK. While perhaps sufficient to achieve at least minimally acceptable heat dissipation, such materials have been found to be subject to corrosion, in that light fixtures manufactured from such conventional materials often rot within a 2-3 year period, requiring their replacement. Plastic materials may also often be conventionally employed in manufacture of such light fixtures. Such materials typically exhibit even lower thermal conductivity (e.g., typically less than 1 W/mK), and are also subject to chemical and other (e.g., UV) degradation such as that described above.
(21) The panel 104 may be fabricated from a carbon fiber material, or another form of carbon providing relatively high thermal conductivity, so as to advantageously provide for improved thermal conductivity, and corrosion/degradation resistance. Any suitable carbon fiber or other carbon material (e.g., amorphous carbon filled composite and the like) may be suitable for use. Carbon fiber may be particularly preferred, and can be integrated into a composite panel 104 through use of any suitable binding matrix material (e.g., epoxy resin, acrylic resin, other polymeric matrix materials, and the like).
(22) As seen particularly well in
(23) As shown, a mounting fixture 120 for hanging or otherwise mounting the light fixture 100 may be provided (e.g., at the center of dome member 102). As shown, mounting fixture 120 may include a ring 122 and/or a hollow central passage 124 therethrough which allows passage of wiring 118a through dome member 102, into UL-approved space 116. Panel 104 may include a small hole 117 therethrough (e.g., about the width of the electrical wire 118b), allowing wiring 118b to pass through panel 104, into UL-approved space 116. Within space 116, an electrical connection (e.g., using wire nuts 126 or other suitable connector) may be completed between wiring 118a and 118b.
(24) In order to facilitate easier electrical connection of wire 118a with wire 118b within space 116, an access door 128 may be provided through dome member 102, for accessing space 116. Door 128 may be secured to dome member 102 by any suitable mechanism, e.g., including screws or the like. In an embodiment, door 128 may snap into place over the opening (e.g., much like a battery compartment door). Such a mechanism may be more easily removed and replaced, as needed. Any suitable mechanism that does not compromise the UL-approved status of the space 116 may be used.
(25) Such an access opening and door 128 may be significantly larger than opening 124 into space 116, so as to allow a person to reach into space 116 and pull wires 118a and 118b out, make the electrical connection, and then push connected wires 118a and 118b back into space 116, through the opening covered by door 128. For example, such an opening may have an area of about 5 in.sup.2 about 20 in.sup.2, or about 6 in.sup.2 to about 15 in.sup.2 (e.g., 23 inches, or 35 inches). While being sufficiently large to allow a person to reach into space 116 and retrieve wires 118a, 118b, and reinsert them after wire nutting or otherwise connecting them together, the opening may be sufficiently small so as to still maintain UL-approval for space 116.
(26) As perhaps best seen in
(27) While at least panel 104 comprises carbon (e.g., carbon fiber), the dome member 102 may also be formed of a similar material, e.g., carbon fiber in a suitable matrix material, such as epoxy resin, acrylic resin, or the like), providing excellent thermal conductivity and degradation resistance characteristics thereto as well. Where the dome member 102 and panel 104 comprise carbon (e.g., carbon fiber), this results in a light fixture 100 that is particularly durable, resistant to degradation in spite of the atmospheric chemistry within the particular environment in which it is employed, and which provides excellent heat dissipation away from the LEDs 112. For example, such a light fixture may be employed in a dairy barn or similar environment where there are relatively high (and chronic) levels of hydrogen sulfide, methane, and other constituents generated from the cattle or other animals. Such chemicals have been found to rot existing and typically employed light fixtures that are currently used in such facilities. Such conditions result in a need to replace lighting fixtures after only 2-3 years of use. The present light fixtures are far more resistant to degradation, and may typically last at least 5 years, at least 7 years, at least 8 years, or at least 10 years, at least 15 years, at least 20 years, at least 25 years, or at least 30 years. Such fixtures may last 10-20 years, or 10-30 years, without need for replacement, under conditions where typical light fixtures rot after only 2-3 years, and require replacement.
(28) One other nuisance associated with such agricultural installations is that in addition to the chemicals generated and emitted by the cattle or other animals being raised, there are often pigeons or other birds who tend to nest in or perch on the existing, typically employed light fixtures. As a result of such nesting, perching, or loitering, the light fixtures also typically become covered and encrusted with the guano of such birds. Such encrustation often further exacerbates the rotting problem, as there are corrosive (e.g., saline and other) components within such guano, which remains long term in contact with the light fixtures.
(29) As shown in
(30)
(31) Dome member 202 differs from dome member 102 in that it includes an exterior surface that is downwardly curved or sloped at an edge portion 234a, and which includes a central portion 234b that is substantially flat. Such a light fixture could be installed in a dairy barn or other desired environment as is (e.g., similar to fixture 100), but the differently shaped dome member 202 also provides the ability to retrofit light fixture 200 into an existing light fixture. For example, it may be particularly advantageous to retrofit fixture 200 into a bell-shaped light fixture such as those that are legacy light fixtures, installed in arenas, gymnasiums, and other similar large volume indoor facilities. Such bell-shaped legacy fixtures do not typically include an LED light source, but rather a lower efficiency, older technology light source such as incandescent, halogen, fluorescent, sodium vapor, or the like. It may be particularly desirable to upgrade such existing legacy light fixtures with a high efficiency LED light source. The light fixture 200 is particularly suited to such a purpose.
(32)
(33)
(34) By forming the support 336 from such materials, the support exhibits less tendency to degrade in corrosive environments such as those described herein. For example, methane, H.sub.2S and other corrosive constituents in sewage treatment or other water treatment plants can cause conventional steel components to quickly degrade in such conditions. Environments near large sources of salt water (e.g., coastal highways or the like) exhibit similarly corrosive environments, relative to conventional steel components for lighting installations. Use of the carbon fiber materials as disclosed herein would significantly increase the lifespan of such lighting components, due to their resistance to corrosion in such environments. For example, at least with respect to coastal environments, deposition rates of NaCl increases exponentially with proximity to the beach or other coastline. For example, in a more typical inland environment, deposition rates for NaCl may be no more than 10, no more than 5, or no more than 3 mg/m.sup.2/day. In a coastal environment (e.g., within 10 miles, within 5 miles, within 3 miles, or within 1 mile of the coast), the rate of deposition may be significantly higher, e.g., such as greater than 50, greater than 60, greater than 75, or greater than 100 mg/m.sup.2/day. By way of further example, a typical deposition rate within 200 m of the coast may be from 300 to 1500 mg/m.sup.2/day. It will be readily apparent that such concentrations of NaCl and elevated concentrations of other salts present in such a coastal environment, coupled with elevated humidity (e.g., elevated time of wetness (TOW) can result in significantly accelerated corrosion of lighting components in such environments. In an embodiment, TOW may be determined based on days per year (e.g., percentage out of 365 days) that relative humidity exceeds 50%. In many coastal environments, such a TOW value may be more than 40%, more than 50%, more than 60%, more than 70%, more than 80%, or even more than 90% of the days in a year. Under such elevated humidity levels, and where there is significant salinity in the atmosphere, corrosion of conventional metallic (e.g., particularly steel, even galvanized steel) is significantly accelerated. Use of the presently described systems would significantly increase the useful lifespan of such lighting components (e.g., light fixtures and supports).
(35) An additional benefit of the presently described systems is decreased weight. For example, a typical galvanized steel lighting installation (fixture and support) easily weighs at least 800 lbs (e.g., 800 to 1000 lbs). While aluminum can sometimes be used in such environments, and is less heavy, it is significantly more expensive, and may still exhibit some level of corrosion problems. A lighting installation similarly sized to the above, but formed from carbon fiber (or a composite of carbon fiber and fiberglass in a suitable resin matrix) may weigh only about 10% that of existing conventional systems (e.g., 80-100 lbs). Some smaller serpentine head exterior lighting installations may weigh somewhat less, e.g., 200 to 400 lbs, although the same size fixture (same size and shape) could be formed using principles described herein, again, at about 10-20% of the conventional weight, e.g., from 40-80 lbs. Where conventional installations fall on a car or other vehicle, they cause massive damage, which can be life threatening to occupants of the vehicle. Use of the presently described systems would significantly reduce safety risks, where such a lighting installation may fall onto a vehicle (e.g., in a crash or the like). For example, typical poles are engineered to shear off bolts 344 if hit by a car or other vehicle. While the pole or other support 336 may thus still fall on the car or other vehicle, toppling of a 100 lb or lighter assembly (light fixture, and support) is far less damaging and dangerous than toppling of an 800 lb similarly dimensioned assembly.
(36) As conventional fixtures typically rot out after 10-15 years or less (sometimes far less, such as 5 years, or 3 years) under conditions as described herein, they could be replaced (e.g., retrofitted) with systems as described herein, which would last significantly longer. Maintenance may also be reduced, e.g., as where 10-15 years of life may currently be possible with frequent sandblasting and resealing (e.g., galvanizing, painting, etc.) of the conventional steel materials, the present systems would provide even longer lifespan, with reduced maintenance requirements.
(37) While the issue of corrosion is described in the context of coastal areas, where airborne salinity is elevated, such conditions may also exist in other conditions, e.g., in winter, where roads are heavily salted. Installation as described herein would reduce corrosion throughout the entire structure (e.g., support pole, arm, any other support components, light fixture, etc.), particularly at the base of such installations, where salt from road salting may be particularly concentrated.
(38) Even where a composite of carbon fiber and fiberglass may be used for the fibrous portion of the composite used to produce such pole or other support components, the majority of the fibers employed may be carbon fiber, as carbon fiber is generally stronger than fiberglass. Such composite materials may also readily be colored (e.g., by incorporating a dye or pigment into the matrix material. For example, the lighting fixture installation could be colored to coordinate for a school or other institution's official colors, or the like.
(39) The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrated and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.