Abstract:
An sealed acorn style luminaire is described. The luminaire has generally separate inflow and outflow valves for pressure equalization in order to minimize the amount of dust and other foreign matter which could enter into the sealed optical compartment thereby reducing the optical characteristics of the fixture. A one way outflow valve and seal is provided in combination with controlled inflow seals to reduce or limit the dirt and other foreign substances in the sealed optical compartment.

Description:
FIELD OF THE INVENTION 
     The present invention is related to outdoor luminaires and in particular to outdoor lighting or street lighting wherein the luminaire optical system is fully sealed to prevent the intrusion of dirt, dust and other materials which would reduce luminaire lumen output. 
     BACKGROUND OF THE INVENTION 
     Outdoor luminaires which are utilized for wide area lighting or street lighting face many challenges during the life of the luminaire. Due to the environmental circumstances and conditions in which the luminaires are utilized, and due to the extensive heating and cooling cycles inflicted upon the electrical and optical system of the luminaire, dirt, dust and moisture intrusion commonly occur into the electrical and optical system thereby affecting the lighting characteristics of the luminaire over time. The penetration of these foreign substances into the luminaire therefore must be taken into account during the design phase of the reflector and light system in order to maintain continued output characteristics over a given length of time. Penetration ratings are provided in order to describe the ability for luminaire housings as well as various optical systems to resist the penetration of both solids and liquids into the sealed compartment defining the optical area. These intrusion protection or ingress protection ratings are designed to help gauge the ability for the seals to inhibit dirt and other foreign material from entering into the luminaire and causing potential performance loss. Commonly, outdoor luminaires have interpenetration protection ratings (IP) in order to gauge the performance of the seals and their ability to prevent dirt and foreign substance intrusion. Intrusion by both foreign substances such as dirt and water on the lenses and other reflective elements of the luminaire affects the performance of the lighting system. The luminaire dirt depreciation for particular conditions in which the luminaire will be installed thus comes in handy to determine overall light loss and maintenance required in order to maintain the luminance or illumination level of the luminaire. By preventing the intrusion of moisture or other foreign substances into the optical system, lower initial lumen output and therefore lower wattage lamps, may be utilized. 
     It is thus desirable to provide an outdoor luminaire which has adequate seals which prevent contaminates such as dust, soot or moisture to collect on the optical system surfaces. This is particularly the case given that these sealed compartments or optical systems undergo intense heating and cooling cycles, thereby changing the pressure differential between the sealed interior space defined within the globe or other optical system area and exterior of the globe, as can be commonly understood. When activated, the lamp causes intense heat within the optical area thereby increasing the air pressure therein and creating a positive pressure system between the sealed internal area or compartment of the luminaire and the exterior area. During cooling, a reverse air pressure system ensues thereby exerting opposite pressure on the seals of the sealed compartment while the system cools thereby allowing inflow of contaminates and other material into the sealed compartment. It is thus desirable to provide a sealed outdoor luminaire which has adequate seals which allow outflow of air from inside the globe or optical area during intense heating and which restricts the inflow of contaminates and other material into the luminaire compartment during the cooling cycle or other negative pressure event. 
     Interpenetration protection ratings for luminaires are often quoted as indicated above for lighting enclosures and luminaires and indicate protection from solids, liquids and impact. Various standards are known for describing the ratings and typically, the IP rating is given with two numbers, the first number indicating the protection against solids while the second number indicating the protection against liquids. It is desirable to provide an IP rating of a luminaire over its lifetime of a minimum of IP66 indicting that there is total protection against dust intrusion and also high protection against liquids. Various other IP ratings may be implemented as it is significantly desirable to provide intrusion protection of dust and other contaminates in the interior portion of the optical area, the optical system of a luminaire including the lamp or other light generating mechanism or component, baffles, shields, reflectors and other elements located within the globe and including the globe. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the sealed acorn luminaire of the present invention wherein the globe is opened and the lamp has been removed; 
         FIG. 2  is a side-section view of the sealed acorn luminaire of the present invention; 
         FIG. 3  is a close-up perspective view of the lamp support base and mounting collar for the sealed acorn luminaire of the present invention; 
         FIG. 4  is a lower perspective view of the intersection between the lamp support base and the mounting collar of the sealed acorn luminaire of the present invention; 
         FIG. 5  is a close-up side-sectional view of the intersection between the lamp support base and the mounting collar for the sealed acorn luminaire of the present invention; and, 
         FIG. 6  is an exploded view of the sealed acorn luminaire of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The sealed acorn luminaire  10  of the present invention is depicted in  FIG. 1  and is comprised of a globe  20  which has mounted therein a reflector  13  and which is topped by a globe top  14 , the globe and globe top being integral or separate as desired. The globe  20  has an open bottom which is permanently sealed to a mounting collar  18 , the mounting collar  18  permanently sealed or affixed and adhered to the bottom open aperture of the globe  20 , the mounting collar  18  hingedly attached by hinge  12  to the ballast housing  133  positioned at the top of a lamp post. The mounting collar  18  is permanently and fixedly attached to the bottom open aperture lip of the globe  20  such that a permanent seal exist between the mounting collar  18  and the globe  20  and no airflow for contaminates is allowed to penetrate between the two structures. The mounting collar  18  has an interior aperture defined by a depending mounting collar extension  21  which, in this embodiment, extends downwardly from the inner periphery of the mounting collar as is depicted in  FIG. 5  in order to sealingly engage the lamp support base  45 . As shown in  FIG. 1 , the lamp support base  45  is received within the aperture defined by the mounting collar extension  21  such that part of the lamp support base  45 , lamp stem or lamp support  46  and lamp  47  are positioned within the globe  20 . The lamp support base  45  may be locked in place within the mounting collar aperture utilizing a number of known locking techniques such as rotation tabs  61  which may fit within openings formed in the mounting collar rim  23  shown in  FIG. 5 . Thus, the lamp support base may be locked in place by rotating the lamp support base  45  such that the tab  61  rides over the top of mounting collar rim  23  and prevents removal of the lamp support base  45  and which also provides sufficient clearance to induce adequate compression on seals maintained on the lamp support base  45 . 
     The sealed acorn luminaire  10  of the present invention provides a sealing mechanism wherein a one-way outflow seal is provided in-between the lamp support base  45  and the mounting collar  18  such that heated gases generated when the lamp  47  is on may escape the interior portion of the globe  20  which may define the optical system of the sealed acorn luminaire  10 . The design of the present embodiment is such that outflow of heated gases may be allowed during heating of the sealed acorn luminaire  10  but wherein the one-way outflow seal or shutter seal  40  only allows outflow of gases and significantly restricts the inflow of air or other contaminates during the cooling cycle. Inflow of air during the cooling cycle of the sealed acorn luminaire  10  after the lamp  47  has been turned off is controlled and may be restricted through the use of wire seal grommet  30  thereby significantly restricting and controlling the seal around the optical system. The wires entering into the system are sealed in order to permit air to penetrate the wire grommet seal with a very high restriction value ensuring that only air and molecules having the same dimension as air or smaller will have a chance to penetrate the optical system of the present sealed acorn luminaire. 
     Turning to the design of the sealed acorn luminaire of the present invention, the globe  20  has globe top  14  and may have an internal reflector  13  as shown in  FIG. 1  and  FIG. 2 . The globe is sealed along a lower periphery thereof to the mounting collar  18  having a permanent seal  17  positioned between the mounting collar seat  18  and the bottom edge or lip of the globe  20 . The globe  20  may be pressed onto the mounting collar seat  19  or the mounting collar  18  through the globe retaining ring  22  which, as seen in  FIG. 3  and  FIG. 6 , is an annular ring which presses downwardly on the lower portion of the globe  20  in order for it to maintain pressured contact with the mounting collar  18 . The mounting collar permanent seal  17  between the mounting collar  18  and the globe  20  may be silicone material in order to permanently seal and prevent airflow or contaminate flow between the mounting collar and the globe thereby adequately and permanently sealing the joint between the structures. The globe retaining ring  22  may have a number of apertures for receiving retaining pins or bolts for maintaining adequate pressure and compressive forces on the globe and the mounting collar. 
     As shown in  FIG. 1 , received within the mounting collar aperture is the lamp support base  45  which supports the stem  46  and lamp  47  such that the lamp  47  may be contained in proper orientation within the globe  20  and particularly with respect to the reflector system  13  depicted herein. In the sealed acorn luminaire design depicted, the optical system retained within the globe  20  is permanently sealed except for the lamp access shutter seal that uses a reusable silicone shutter seal  40  to guarantee the continued seal over an extended length of time regardless of the quantity of lamp changes that has occurred. The sealing mechanisms described provide for the sealed acorn luminaire of the present invention to ensure that no water or dust can penetrate the optical system even during the cooling stages which cause negative pressure between the globe and the exterior atmosphere. The negative pressure event tries to force dust and moisture around the luminaire into the interior of the optical system through the seals. Breathing of the optical system occurs but is controlled and restricted by the seals around the wire seal grommet  30 . 
     Referring specifically to  FIG. 1 , an annular shutter seal  40  is provided which seals the point of contact between the lamp support base  45  and the mounting collar  18 . Particularly, turning to  FIG. 4  and to  FIG. 5 , the mounting collar has a downwardly extending mounting collar extension  21  for engagement of the seal  40  positioned on the lamp support base  45 . The lamp support base  45  has an annular seal channel  41  which is defined by an upper seal wall  42  and a lower seal wall  43 , the seal channel  41  receiving the shutter seal  40  therein. The shutter seal  40  is placed within the seal channel and maintained in position on the lamp support base. As depicted in the present embodiment, the shutter seal  40  is annular but may have many different shapes as is known in the art. The lamp support base seal channel  41  receives the shutter seal and maintains the position of the shutter seal therein through the use of friction fit, adhesives or other known mechanisms. The interface between the lamp support base  45  and in particular the seal channel  41  and the mounting collar  18 , and particularly the mounting collar extension  21 , is shown in  FIG. 5  wherein the mounting collar extension  21  extends downwardly and contacts the shutter seal  40 . 
     The shutter seal  40  is designed to have an upstanding wall section  51  which is adjacent to the base of the lamp support base seal channel  41 , a generally flat washer section  50  and a curved section extending between the washer section  50  and the upstanding wall section  51 , the generally curved section  52  interposed therebetween. The washer section  50  of the shutter seal  40  is positioned between the mounting collar extension  21  and the lower seal channel wall  43  and the design interface between the lamp support base  45 , mounting collar  18  and the shutter seal  40  is such that outflow of heated gases is allowed through the shutter seal  40  but that inflow pressure caused by cooling of the lamp and internal space of the globe  20  increases the sealing pressure shown in  FIG. 5  thereby creating a one-way shutter seal and preventing or restricting flow of gases and other contaminates into the globe through the shutter seal  40 . As indicated, hot air or other gas is created during the positive pressure outflow heating cycle, the outflow occurs through the shutter seal  40  and around the mounting collar extension  21  but inflow of gases, air and other contaminates is restricted due to the increased pressure on the shutter seal walls shown in  FIG. 5  by the arrows. The flexible silicone shutter seal  40  may be comprised of many different materials, however, silicone may be utilized since it assures the seal between the shutter and the mounting collar has no memory loss and allows resealing once reassembled on the collar after maintenance. During the positive pressure cycle, temperature inside the globe increases and positive pressure forces some air to be expelled from the optical system maintained within the globe  20  through the flexible silicone seal  40  and potentially through the wire seal grommet  30  until the pressure inside the globe  20  and the exterior air equalizes. The shutter seal  40  is designed, as depicted with the current structure set forth herein, as a one-way seal or valve in order to provide some resistance to air exiting the optical system but providing significant resistance to incoming air as shown in  FIG. 5 . 
     In reference to the figures, one embodiment is depicted implementing the one-way outflow valve or seal  40  set forth herein, wherein the seal  40  is pinched between the mounting collar extension  21  which extends downwardly from an upper peripheral flange towards the lamp support base  45 . Generally, utilization of a one-way outflow seal or valve as depicted and may implemented in many different structures which would necessarily allow outflow of increased pressure gases contained with the globe  20  after initiation or starting of the high intensity discharge lamp or induction lamp  47 . Outflow of gas, as previously indicated, may be exhibited through the shutter seal  40  and possibly through the wire seal grommet  30  which connects the electrical wiring  31  to the internal wiring  33  on the other side of the lamp support base  45 . In the present embodiment as depicted in  FIG. 5 , the mounting collar extension  21  pressures the shutter seal  40  and particularly the flat annular portion  50  of the shutter seal between the mounting collar structure and the lamp support base structure. Many different implementations of such a valve seal may be utilized and the disclosure set forth herein is intended to cover such implementations and alternative constructions for one-way outflow valve sealing mechanisms which may be utilized and interposed between the lamp support base  45  and the mounting collar  18 . Additionally, while implemented in the embodiment depicted, a seal channel is formed for receptively and frictionally retaining the seal  40  within the proper location of the lamp support base  45 . However, many different constructions for retention of the one-way valve seal  40  depicted may be implemented but not necessarily requiring a seal channel or upper and lower seal walls to trap the valve seal in position as is disclosed in this embodiment. Multiple embodiments may be interpreted from the various disclosures herein and the examples given are not to be construed as being limiting as one of ordinary skill in the art will interpret the inclusion of the valve seal construction between the lamp support base and the mounting collar in many different constructions and form. 
     In conjunction with the outflow valve seal  40  depicted in the figures, an inflow valve may also be utilized. Outflow valving may be necessary during heating of the luminaire caused by turning the lamp  47  on. The heated gases may then escape the sealed compartment of the optical chamber contained within the globe  20  so as to equalize the pressure from the interior of the globe  20  to the exterior environmental atmosphere pressure. Alternatively, upon turning off the lamp  47  of the luminaire, cooling of the air within the optical system and interior of the globe again causes disequilibrium thereby initiating potential inflow of air and other contaminates into the interior of the globe and the optical assembly. Due to the expansion as the joint expands during cooling of the luminaire of the one-way valve assembly  40  shown herein, inflow pressure depicted in  FIG. 5  tightens the one-way outflow seal  40  and prevents the inflow into the globe and optical assembly of air and other contaminates through this valve. Breathing of the luminaire optical system of the present invention and inflow of air to equalize the pressure contained within the luminaire optical assembly and within the globe during such a negative pressure event may be accomplished through a one-way inflow valving mechanism implemented through the wire seal grommet  30  which surrounds the electrical wiring  31  on the exterior of the lamp support base  45 . Wire seal grommet  30  has, at a location adjacent to the side wall of the lamp support base  45 , a grommet composed of silicone or other similar valve and seal material which is designed to allow the controlled inflow of air into the interior of the globe and optical assembly area during a negative pressure event wherein comparative negative pressure is present in the interior of the globe relative to the exterior of the globe as a result of cooling. The cooling of the interior space of the globe therefore naturally creates the negative pressure in the interior of the globe assembly due to the seals located at all junction points and the inflow of air and other material is controlled through the wire seal grommet  30  due to the inability of air and other contaminates to enter into the globe space through the outflow shutter seal  40 . The wire seal grommet  30  may control the inflow of air through the use of a silicone material to form the grommet and the sealing area around the aperture formed in the side wall of the lamp support base  45  through which the wires extend. The amount of inflow of the air during a negative pressure event as indicated, can be controlled through the angle, thickness and length of the wire seal grommet  30  extending along the electrical wiring  31 . As shown in  FIG. 5 , the wire seal grommet  30  may extend along a predetermined length of the electrical wiring  31  and possibly into the interior of the lamp support base  45  contacting wiring  33  on the interior thereof The wire seal grommet  30  has a sufficient length and sufficient thickness along the wiring and at the aperture of the lamp support base through which the electrical wiring extends in order to allow breathing of the optical system to occur but controls and restricts the inflow of air into the optical system and the internal area defined by the globe. The wire seal grommet  30  of the present invention is designed so as to permit air to penetrate having an R factor of about 600 or a relative high restriction value such that only air and molecules having the same dimension as air or smaller will have a chance to penetrate into the interior of the optical system. The R factor is the reistance to air flow, defined by the following formula: R=h/CFM where R is the air resistance, h is the pressure measured in inches of water and CFM is the flow rate in cubic feet per minute. The wire seal grommet  30  of the present invention may be designed to control the amount of inflow air into the system by alternating the construction of the grommet itself, the elements of which is made, modifying the thickness thereof or extending the length of the grommet along the electrical wiring. 
     As shown in  FIG. 4 , individual or separate wire seal grommets may be provided through the dual wires which enter into the interior of the luminaire and particularly through the lamp support base  45  as shown. Each of these grommets may extend around the individual wires as they approach the wall of the lamp support base but may be conjoined through a single silicone seal on the interior wall of the lamp support base  45  as is shown in  FIG. 3 . Alternative constructions however may be implemented in order to maintain and control the inflow of air during the negative pressure event as depicted and discussed herein. The seals are designed so as to create a strong seal as inside pressure decreases during a cool down cycle thus exerting a greater restriction on incoming air and contaminates coming from the outside as shown in  FIG. 5 , thereby increasing the sealing functionality of the shutter seal  40  during a negative pressure event while allowing the inflow of air through the wire seal grommet  30  described herein. 
     As shown in  FIG. 1 , the lamp stem  46  extends the lamp  47  upward and into the interior of the globe and positions it as necessary relative to the reflector system  13  including the lower reflector collar  13   b  and the conical reflector  13   a . Primary reflector interposed in-between the conical reflector  13   a  and lower reflector collar  13   b  works in combination with the entire reflector system  13  in order to provide an adequate cutoff designation for the acorn style luminaire thereby providing a cutoff distribution having less than a predetermined amount of candelas per 1,000 lamp lumens at angles of 90 degrees and above and, said predetermined level of candelas being at or about 25. Further, less than 100 candelas per 1,000 lamp lumens may be emitted at angles of 80 degrees from nadir and having an up light contribution of less than 2 percent of luminaire lumens output depending upon the specific construction of the cutoff reflector depicted, the type of refractor or reflector utilized in combination with the formation of prisms on the interior or exterior of the globe and other unique features used in combination with the high efficacy reflector and light transmitting vertical internal prismatic globe which may be utilized. 
     The lamp  47  shown herein may be a high intensity discharge lamp such as high pressure sodium on metal halides having a wattage output of up to 250 W. As shown in  FIG. 2 , the lamp  47  is depicted as being substantially surrounded by the reflector system  13  of the acorn luminaire shown. The lamp support stem  46  may be affixed to the lamp support base  45  through the utilization of attachment mechanisms, screws, adhesives or other known mechanisms known to those skilled in the art. Alternative structures may be implemented in order to position the lamp in proper orientation with respect to the reflector as desired and as is known. As shown in  FIG. 6 , the combined construction of the acorn luminaire of the present embodiment may be implemented through the use of the top portion of the luminaire acorn luminaire  14  having the reflector system  13  included, affixed or held therein, the globe  20  held in place through the retention ring  22  on top of the mounting collar  18  with the lamp support stem  45  inserted and retained therein through known retention mechanisms and techniques. It is to be understood that the general concepts and examples provided herein are utilized as exemplary only in order to provide a better understanding of the novel features of the sealed acorn luminaire described and claimed in the appended claims. Many alternative constructions for the various structures and embodiments depicted herein may become known to one of ordinary skill in the art after review of the entire disclosure, drawings and claims attached hereto.