AU2012100798A4 - Downlight Housing for Holding a Heat Sink - Google Patents

Abstract

Abstract A downlight fixture comprising a mounting ring configured to mount the downlight fixture in a hole in a mounting surface; means for supporting a lamp or lamp socket above the mounting ring; one or more heat sink retention members, the heat sink retention members being directly or indirectly coupled to the mounting ring and extending upwards therefrom; and a heat sink retained by the heat sink retention members in thermal contact with the lamp or lamp socket, wherein the heat sink is able to be retained by the heat sink retention members in a plurality of positions along the length of the heat sink retention members. Figure 1

Description

DOWNLIGHT HOUSING FOR HOLDING A HEAT SINK Field of Invention This invention relates to downlight fixtures. More particularly, this invention relates to a downlight fixture having a housing able to hold a heat sink in a number of positions. Background to the Invention Downlights are ceiling-mounted lighting fixtures that can be recessed into a ceiling cavity and shine downwards into a room. Downlights have become widespread because they are a stylish source of effective lighting. They are also unobtrusive because they do not protrude into a room to the extent of other types of light fixture. Downlights are used in many different situations, including residential and commercial buildings. They can be installed in both new and existing constructions by mounting in a ceiling panel or other ceiling installation. Conventional downlight fixtures include a mounting ring for mounting the downlight in a hole in a ceiling and a structure that supports a lamp socket above the mounting ring. Downlight fixtures often also include a lamp housing (sometimes known as a reflector) with a reflective inner surface to channel light downwards into a room. LED downlights have an LED supported above the mounting ring and typically comprise a heat sink device for dissipating the heat generated by the LED. One type of heat sink commonly used in downlight fixtures is the "fin" type heat sink, which has an array of fins extending outwards from a core or base. The fins function to increase the surface area of the heat sink, thereby acting to dissipate heat as efficiently as possible. Conventional LED downlight fixtures have housings in which the heat sink is fixedly or rigidly attached to the housing in thermal contact with the LED so that it can act to dissipate heat. This may limit the ability of a given downlight fixture to accommodate components of different size or shape. For example, some downlight models have different sized reflectors to other downlights. In addition, LEDs require heat sinks large enough to adequately dissipate the heat generated the greater the power output of an LED, the greater the size of heat sink required. Where

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downlight housings are not able to accommodate different sized components, each model of downlight may require its own design of housing. This results in high costs of design, manufacture and supply. Object of the Invention It is an object of the invention to provide an improved downlight housing able to accommodate components of different size and shape. Alternatively, it is an object to provide an improved downlight or recessed lighting fixture which addresses one or more of the problems discussed above. Alternatively, it is an object of the invention to at least provide the public with a useful choice. Summary of the Invention According to a first aspect of the invention, there is provided a downlight fixture comprising: a mounting ring configured to mount the downlight fixture in a hole in a mounting surface; means for supporting a lamp or lamp socket above the mounting ring; one or more heat sink retention members, the heat sink retention members being directly or indirectly coupled to the mounting ring and extending upwards therefrom; and a heat sink retained by the heat sink retention members in thermal contact with the lamp or lamp socket, wherein the heat sink is able to be retained by the heat sink retention members in a plurality of positions along the length of the heat sink retention members. Preferably, the heat sink is a fin-type heat sink. More particularly, a fin-type heat sink comprises a plurality of fins fanning radially outwards and extending along the length of the heat sink. Preferably, the heat sink retention members comprise means for frictionally holding the heat sink relative to the heat sink retention members. More preferably, the means for frictionally holding comprises flanges adapted to extend between fins of the heat sink. In preferred embodiments of the invention, the flanges extend parallel to the fins of the heat sink. As such, the heat sink is able to slide relative to the flanges and be positioned at any point along the length of the flanges. 2 Preferably, the means for frictionally holding further comprises a strap connected to the heat sink retention members and encircling the heat sink to hold the heat sink in position. More preferably, the strap comprises means for tightening and releasing the strap around the heat sink. In preferred embodiments of the invention, the mounting ring comprises at least one flange on an outer edge for abutting a first side of the mounting surface. In preferred embodiments of the invention, the downlight fixture comprises one or more mounting arms, each connected to one of the heat sink retention members and adapted, in use, to exert a force on a second side of the mounting surface to hold the downlight fixture in the hole in the mounting surface. Preferably, the mounting arms are adjustable between a first, biasing configuration and a second, non-biasing configuration. In some embodiments, the mounting arms each comprise a helical torsion spring comprising at least two arms, wherein a first arm is adapted to rotationally displace in use such that, in the first configuration, a force is exerted on the second side of the mounting surface and a second arm is held in fixed relation to the respective heat sink retention member. Preferably, in the second, non-biasing, configuration, the second arm is not held in fixed relation to the respective heat sink retention member. More preferably, the mounting arms each comprise a double helical torsion spring comprising a first, central arm adapted to rotationally displace in use such that a force is exerted on the second side of the mounting surface and two other arms, each held in fixed relation to the respective heat sink retention member in the first configuration and released therefrom in the second configuration. Preferably, the heat sink retention members each comprise at least one first projection adapted to receive part of the mounting arms. More preferably, the at least one first projection is adapted to receive a coil of the helical torsion spring.

Preferably, the heat sink retention members each comprise at least one second projection adapted to hold part of the mounting arms in fixed relation to the heat sink retention member. For example, the at least one second projection may be adapted to hold an arm of the helical torsion spring in fixed relation to the heat sink retention member. Preferably, the first and second projections extend planarly inwards into a hole in each heat sink retention member. Further aspects of the invention, which should be considered in all its novel aspects, will become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the invention. Brief Description of the Drawings One or more embodiments of the invention will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which: Figure 1 is a side view illustration of a downlight fixture according to one embodiment of the invention; Figure 2 is an isometric view illustration of the heat sink retention members shown in Figure 1. Brief Description of Preferred Embodiments of the Invention In the following description, the invention will be described with reference to its use as a downlight in a ceiling. This is one common way the invention is expected to be used but it should be understood that this is not limiting to the invention. The "downlight" fixture that is the subject of the invention may be used in any situation, for example, it may be mounted in a wall, floor or other building structure. The term "downlight" is used in the sense that such light fixtures are able to be used in a position in which they point down, since they are commonly used in this way. Reference to relative positional terms such as "above", "under" or the like when used in this specification should be understood to refer to the downlight fixture in a ceiling-mounted orientation and therefore such terms are not limiting to the invention if the fixture is used in a different situation. 4 Figure 1 is a side view illustration of a downlight fixture 10 according to one embodiment of the invention. Downlight fixture 10 comprises a mounting ring 12 configured to be inserted into a hole in a ceiling, building structure or other mounting surface to mount the downlight fixture. The hole preferably has substantially the same diameter as the rim of the mounting ring 12 such that the downlight can be friction fitted in the hole. Mounting ring 12 may comprise a flange 13 on an outer edge, which in some embodiments may be formed by a detachable ring plate. When mounted in a hole in a mounting surface, flange 13 abuts the surface of one side of the mounting surface in which the hole is made. For example, flange 13 abuts the downward facing surface of the ceiling. Flange 13 limits the extent to which the downlight fixture can be inserted into the mounting surface. The flange prevents the upward movement of the downlight in the hole over time, for example caused by vibrations. A lamp is supported above the mounting ring by appropriate means. In the embodiment shown in Figure 1, an LED lamp 14 is supported approximately centrally above the mounting ring by means of heat sink 18. The lamp 14 may be screwed into the bottom of the heat sink 18, for example. LED lamp 14 may be the type of lamp consisting of an array of individual LEDs. In other embodiments, the lamp may comprise a LED lamp housed within a LED module. In still further embodiments, the downlight may comprise a lamp socket configured to receive other types of lamps, e.g. screw bulbs, bayonet bulbs, spotlights, halogen lights or any other light emitting device. In some embodiments, the downlight fixture may comprise frame members that extend upwards from mounting ring 12 and act to support the lamp 14. Downlight 10 also comprises a heat sink 18 for dissipating heat created by the LED lamp 14 to the surrounding air. The heat sink 18 may be a fin-type heat sink, as illustrated in Figure 1 and as known in the art, having a plurality of radially projecting fins 40. The heat sink 18 is mounted on top of, and in thermal contact with, the LED lamp 14. Downlight 10 may further comprise a reflector 16 that has a reflective interior surface to channel light downwards into the room, as is known in the art. Reflector 16 may be able to be removed from the downlight through the mounting ring if desired. At its top end, reflector 16 is positioned .9 close to lamp 14 such that the majority of the light emitted by the lamp is channelled through the reflector, downwards into the room. The downlight 10 also comprises one or more elongate heat sink retention members. In the embodiment shown in Figure 1, there are two heat sink retention members 19 that are coupled to the mounting ring 12 and extend upwards therefrom. The description will now also refer to Figure 2, which is an isometric view illustration of the heat sink retention members 19 shown in Figure 1. The retention members 19 may comprise male members 27 that are adapted to engage with slots in the mounting ring 12, for example. In other embodiments, the retention members may be indirectly coupled to the mounting ring, for example through an intermediary frame member. Heat sink retention members 19 retain the heat sink 18 in such a way that the heat sink is able to be retained in a number of positions along the length of the heat sink retention members 19. There will now be described, with reference to Figure 1, one manner in which heat sink retention members may hold a heat sink in such a way. Heat sink retention members 19 may be able to frictionally hold the heat sink 18 in position. The retention members 19 comprise an elongate, substantially planar body 21 with flanges 22 extending substantially perpendicularly from the body 21. In downlight fixture 10, the flanges 22 are aligned parallel to the fins of heat sink 18. The effect of the flanges 22 extending between the fins of the heat sink 18 is that the heat sink is frictionally retained in relation to the retention members 19. For example, the flanges 22 limit the extent to which heat sink 18 can rotate. Strap 11 encircles the heat sink 18 and assists in holding it in place relative to the retention members 19. Strap 11 may be coupled to the retention members in some manner. In the embodiment of Figure 1, for example, the strap 18 passes through holes 23 in the retention members 19. In the embodiment of Figure 1, strap 11 comprises a thin band of metal having two flanged ends connected together by a screw 41. As such, the strap 11 can be tightened to hold the heat sink 18 firmly in place, or loosened to allow the heat sink 18 to be removed or moved. In use, the heat sink retention members 19 enable the position of the heat sink to be varied along the length of the heat sink retention members. The elongate flanges parallel to the fins of the heat sink mean that the heat sink can be frictionally held in any position along the length of 6 the retention members. This enables the same downlight fixture to be able to accommodate components of differing sizes. For example, Figure 1 illustrates downlight fixture 10 used with reflector 16. The same downlight fixture can be used with a reflector that is smaller or larger the position of the heat sink 18 can be adjusted to retain the LED lamp 14 in position above the top of the reflector 16 with the heat sink in thermal contact with the lamp 14. Moreover, the downlight fixture can also retain heat sinks of different sizes. The heat sink 18 shown in Figure 1 is of a size suitable for use with LED lamp 14, i.e. its size is sufficient to dissipate the heat from the lamp. If a lower power lamp is used then it may be more cost effective to use a smaller heat sink, since less heat energy would need to be dissipated. The present invention therefore enables the same design of downlight housing to be used with downlight components of differing sizes. This reduces manufacturing cost, reduces the number of redundant products and increases efficiencies. Downlight 10 may further comprise one or more mounting arms 17 in rotational co-operation with frame members 15. In the embodiment shown in Figure 1, the mounting arms 17 take the form of double helical torsion springs which, when the downlight is mounted in a ceiling, are pushed upwards by the upper surface of the ceiling and are held in tension exerting a force on the upper side of the mounting surface in which the downlight is mounted. Since flange 13 prevents the downlight fixture moving up through the hole, the downlight fixture is held securely in position. Mounting arms 17, together with flange 13, hold the downlight in the correct vertical position even if the mounting ring does not friction fit in the hole. In other embodiments, the mounting arms may comprise other components in addition to the torsion springs, for example leg clips or the like. Heat sink retention members 19 comprise two upper projections 24 on which are mounted the coils of the torsion springs. The retention members 19 also comprise two lower projections 25 that are positioned for holding a part of the torsion spring in fixed relation to the heat sink retention member. For example, an arm of the torsion spring can be tucked behind each lower projection 25 and held in place by means of the torsion in the spring. Preferably, the upper and lower projections extend inwards into a hole 26 in the heat sink retention member. This allows the torsion spring to be manipulated from inside the downlight fixture housing, the advantages of which will become apparent in view of the ensuing description. 7 The torsion springs of mounting arms 17 are adjustable between a first, biasing configuration and a second, non-biasing configuration. Figure 1 illustrates mounting arms 17 in the first, biasing configuration. In this configuration, end arms (not shown) of mounting arms 17 extend downwards and are held in fixed relation to heat sink retention members 19 by means of being positioned behind lower projections 25. Mounting arms 17 are configured such that, when placed in the configuration illustrated in Figure 1, the torsion springs is held in tension. Therefore central arm 32, which extends downwards towards mounting ring 11, is biased rotationally downwards. In use, mounting arms 17 are sufficiently long so that, when downlight fixture 10 is mounted in a ceiling hole, the upper surface of the ceiling causes rotational displacement of mounting arms 17 upwards. As a result, central arm 32 is held under tension and the mounting arms exert a downwards force on the upper surface of the ceiling. Since flange 13 prevents the downlight fixture moving up through the hole, the downlight fixture is held securely in position. In the first configuration thus far described, downlight fixture 10 is difficult to install and remove from the ceiling. Pushing upwards on central arm 32 requires an increasingly large force to displace it. To insert the downlight fixture into the ceiling hole the central arm needs to be pushed far upwards, which is difficult. Likewise, to remove the downlight fixture when the spring is in the first configuration requires downwards pull on mounting ring 11, which causes the central arm 32 to move upwards. However, in doing so, the tension in the spring again increases and it becomes increasingly difficult to pull mounting ring 11. Continued pulling of the mounting ring may damage the ceiling. To make the downlight fixture easier to both install and remove from the ceiling hole, mounting arms 17 can be adjusted to a non-biasing configuration. In the non-biasing configuration, end arms are pushed off the lower projections 25 such that the arms are no longer held in position by the projections. Since in the first configuration, the spring is in tension, moving the end arms off projections 25 causes the end arms to move in front of the projections and the tension in the spring to be released. As a result, central arm 32 is able to be moved upwards with little difficulty. When the mounting arms 17 are in the non-biasing configuration, downlight fixture 10 can be easily installed in the ceiling hole by pushing central arm 32 upwards, pushing the downlight fixture into the hole such that the mounting ring is friction fitted in the hole and putting the 8 mounting arms in the biasing configuration by moving end arms onto lower projections 25. A person can move end arms onto lower projections 25 by reaching up through mounting ring 11 with their hands, using a screw driver or any other means. Furthermore, downlight fixture 10 can be removed from the ceiling hole by removing lamp housing 15 from the downlight fixture by pulling it downwards and then moving the end arms off lower projections 25 before pulling down on mounting ring 11, resulting in central arm 32 being pushed upwards so that it can easily pass through the hole without damage to the hole or the downlight fixture. The downlight fixture mechanism described above is easy to assemble because the mounting arms 17 can be connected onto the heat sink retention members 19 while the spring is not under tension. Only after the mechanism has been assembled, and the downlight fixture installed into the ceiling, are the end arms moved behind projections 25, thus giving the spring tension. The invention therefore provides easier assembly compared to some prior arrangements, in which parts are assembled under tension. In the preferred embodiment of the invention shown in Figure 1, there are two heat sink retention members 19 positioned diametrically opposite one another on which are mounted mounting arms. In other embodiments, other numbers of retention members may be provided, including one or three or more. Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to". The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference. Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

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The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features. Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth. It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention. 10

Claims (18)

1. A downlight fixture comprising: a mounting ring configured to mount the downlight fixture in a hole in a mounting 5 surface; means for supporting a lamp or lamp socket above the mounting ring; one or more heat sink retention members, the heat sink retention members being directly or indirectly coupled to the mounting ring and extending upwards therefrom; and a heat sink retained by the heat sink retention members in thermal contact with 0 the lamp or lamp socket, wherein the heat sink is able to be retained by the heat sink retention members in a plurality of positions along the length of the heat sink retention members.

2. A downlight fixture as claimed in claim 1, wherein the heat sink is a fin-type heat sink. 5

3. A downlight fixture as claimed in any one of the preceding claims, wherein the heat sink retention members comprise means for frictionally holding the heat sink relative to the heat sink retention members. 0

4. A downlight fixture as claimed in claim 3, wherein the means for frictionally holding comprises flanges adapted to extend between fins of the heat sink.

5. A downlight fixture as claimed in claim 3 or 4, wherein the means for frictionally holding further comprises a strap connected to the heat sink retention members and encircling 25 the heat sink to hold the heat sink in position.

6. A downlight fixture as claimed in claim 5, wherein the strap comprises means for tightening and releasing the strap around the heat sink. 30

7. A downlight fixture as claimed in any one of the preceding claims, wherein the mounting ring comprises at least one flange on an outer edge for abutting a first side of the mounting surface.

8. A downlight fixture as claimed in claim 7, wherein the downlight fixture comprises one or 35 more mounting arms, each connected to one of the heat sink retention members and adapted, in use, to exert a force on a second side of the mounting surface to hold the downlight fixture in the hole in the mounting surface. 11

9. A downlight fixture as claimed in claim 8, wherein the mounting arms are adjustable between a first, biasing configuration and a second, non-biasing configuration. 5

10. A downlight fixture as claimed in claim 9, wherein the mounting arms each comprise a helical torsion spring comprising at least two arms, wherein a first arm is adapted to rotationally displace in use such that, in the first configuration, a force is exerted on the second side of the mounting surface and a second arm is held in fixed relation to the respective heat sink retention member. 0

11. A downlight fixture as claimed in claim 10, wherein in the second, non-biasing, configuration, the second arm is not held in fixed relation to the respective heat sink retention member. 5

12. A downlight fixture as claimed in any one of claims 9-11, wherein the mounting arms each comprise a double helical torsion spring comprising a first, central arm adapted to rotationally displace in use such that a force is exerted on the second side of the mounting surface and two other arms, each held in fixed relation to the respective heat sink retention member in the first configuration and released therefrom in the second 0 configuration.

13. A downlight fixture as claimed in any one of claims 8-12, wherein the heat sink retention members each comprise at least one first projection adapted to receive part of the mounting arms. 25

14. A downlight fixture as claimed in claim 13 when dependent on claim 10, wherein the at least one first projection is adapted to receive a coil of the helical torsion spring.

15. A downlight fixture as claimed in any one of claims 8-14, wherein the heat sink retention 30 members each comprise at least one second projection adapted to hold part of the mounting arms in fixed relation to the heat sink retention member.

16. A downlight fixture as claimed in claim 15 when dependent on claim 10, wherein the at least one second projection is adapted to hold an arm of the helical torsion spring in 35 fixed relation to the heat sink retention member. 19

17. A downlight fixture as claimed in claim 15 when dependent on claim 13, wherein the first and second projections extend planarly inwards into a hole in each heat sink retention member. 5

18. A downlight fixture substantially as hereinbefore described with reference to any one of the embodiments shown in the figures 13