Two part fire rated light

Abstract

The light fitting comprises a first unit 6 including a fire-resistant housing 1 for mounting in an aperture of a partition 2 and securing (e.g., by a clamping arrangement 3) to the partition, and a second unit 7 releasably supportable by the first unit (e.g., by a twist-lock bayonet fitting 8+8A), optionally at least partially within the housing. The second unit comprises a heat sink 9 releasably attached (e.g., by screws, bolts and / or clamping) to a solid-state light source (e.g., LED board 10), with a non-adhesive thermal interface material 100 (e.g., a graphite sheet) between the light source and heat sink. The first unit may be connectable to a power supply for supplying power to the second unit and light source. The second unit may comprise circuitry for operating the light source from alternating current supplied from the first unit. The second unit may comprise a bezel 11 for holding the light source and optionally concealing the aperture in use.

Description

The first commercially available white light LED’s for use in Fire Rated Downlights were in the form of lamps, the most popular design being the GU10 lamp. Although GU10 lamps were more efficient and had a longer life than say, incandescent lamps, the quality of light (colour temperature) output was poor. This was due to the need for a compact design of lamp that did not allow for the use of large heatsinks and sophisticated electronics necessary to support the use of more powerful LED’s. This problem was addressed by the introduction of the Integrated Fire Rated Downlight (IFRD) the first of which was the JCC Fireguard 7 fixture. Other companies have since entered the market with similar designs. These IFRD designs took advantage of the cavity above the partition they were secured to. This meant that the light designer could use the space in the cavity to design IFRD’s with larger heatsinks and more sophisticated electronics, thereby enabling the use of more powerful LED’s with a much longer life and producing more lumens / watt of light than LED lamps such as GU10 and still keeping the slimline design of the light source and bezel. The disadvantage of these IFRD’s is that the design was an integrated build. The result of this type of IFRD design was that when the LED light needed to be replaced the whole IFRD had to be removed from the partition and unlike the GU10 lamp this could only be done by a qualified person since the IFRD is connected to the electrical supply. So the integrated design and build of IFRD’s sacrificed the serviceability of GU10 lamps for a longer life, higher levels of lumens / watt and brighter light output. This issue of serviceability was partially addressed by GB2514685 which enabled the LED light source to be removed while leaving the remaining parts of the IFRD still in situ. All IFRD’s have a long life but they do not last forever. They were first installed in 2009 and since then more than 30 million units have been installed in the UK alone. The first installed IFRD’s are now entering the period when they will start to fail at which time they will need to be removed and replaced. Since the historical annual sales growth of these IFRD’s has been exponential then looking forward in time the rate at which these IFRD need to be replaced is predicted to grow exponentially. The problem of how to dispose of all these redundant fixtures will apply to many types of LED lights not just IFRD LED lights. In order to address this problem of disposal, the European Single Lighting Regulations for the design of new LED fixtures EU 2019 / 2020 eco design and the three Directives EC 244 / 2009, EC245 / 2009 and EU 1194 / 2012 came into force in 2021. These Regulations are to encourage manufacturers of LED fixtures to consider the circular economy when designing new LED fixtures. The major points of these Regulations are that in the future the housings that hold the LED light source should be designed to be reusable and LED light units should be designed to be replaceable and in the event of recyclability, light fixtures should be designed to be easily disassembled during the recycle process. The UK Government have stated that the UK will follow these regulations. Most IFRD on the market use a power supply unit to convert mains supply into a suitable voltage for the LED board. These power supply units are large in size so are positioned in the cavity above the partition and some IFRD's have this power supply unit mounted to the fire resistant housing. Most IFRD on the market also use large heatsinks to keep the LED below the Tj temperature. If the Tj temperature is exceeded the LED will not perform to the manufacturer’s specification becoming less efficient and have a significantly reduced life. These heatsinks are fixed to an inside face of the fire resistant housing or in some designs of IFRD’s the heatsink is fixed to an outer face of the fire resistant housing. These design features of current IFRD means that if the power supply unit fails or the LED mounted inside the bezel fails then the whole unit needs to be removed from the partition and replaced by a new IFRD. Since the IFRD is connected to the mains electricity supply this operation can only be performed by a qualified person. Also once removed from the partition, since the IFRD is built has a single closed unit, it is not easily disassembled during the recycle process. This invention relates to the design of a Fire Rated Downlight with an LED light that mitigates at least some of the above issues and follows the recommendations made by the European Single Lighting Regulations. The main principal of the invention is that the Fire Rated Downlight consists of two parts, the first part is the upper assembly and the second part is the lower assembly. The upper assembly may sit in a cavity above the partition and is attached to the partition and is made up of only passive component parts so that, once installed in the cavity, the upper assembly stays in situ for the life of the partition and so the upper assembly can be continuously reused. The electronic components when mounted on a printed circuit board adjacent to the LED light source remove the need for a separate power supply unit to drive the LED light source. Such power supply units are usually positioned above the partition to which the downlight fixture is attached and connect the downlight fixture to the mains supply. The second part is the lower assembly that includes the heatsink all of the components in the Fire Rated Downlight design that are likely to deteriorate and eventually fail, such as the electronic components and the LED. The lower assembly is designed so that a lay person can easily remove the lower assembly from the upper assembly without the use of tools. Also the lower assembly is designed to be easily disassembled during the recycle process. To achieve this the heatsink is attached to the bezel, which includes the LED board, with screws or releasable clamps. By using modern slim line LED electronic boards which include the LED light and all the electronic components necessary to drive the LED light, such as those boards supplied by Seoul Semiconductor Device, it is possible to mount these boards inside the bezel of the lower assembly. Thereby avoiding the need for a power supply unit situated in the cavity above the partition. With this new technology the Fire Rated Downlight requires a much smaller heatsink to keep the temperature of the LED below the Tj temperature. The invention takes into consideration The European Single Lighting Regulations and can be achieved by using currently available technology. The invention allows the Lighting Designer to consider the Fire Rated Downlight to be made up of two separate parts. The first part is an upper assembly that sits in the cavity above the second side of a partition and is attached to the partition and connected to the electricity supply. It is preferred that the upper assembly is designed to be made from passive components, such as metal and plastic. The use of passive long life parts only, in the design of the upper assembly means that the upper assembly, once attached to the partition and connected to the electrical supply can stay in situ and never needing to be replaced for the life of the partition and is therefore continuously reuseable. As recommended by the European Single Lighting Regulations The second part is a lower assembly that contains the heatsink and the LED light source and all the electronic components necessary to power the LED all mounted on a single slim line board of the type supplied by Seoul Semiconductor Devices. This lower assembly is releasably attached to the upper assembly both mechanically and electrically. The lower assembly contains all of the components with a shorter usage life such as the LED’s and electronic parts and since the lower assembly will eventually need to be replaced it is designed to be removed by a lay person without the use of tools and because the heatsink is attached to the LED board by screws or clamps the lower assembly is easily disassembled during recycling. As recommended by the European Single Lighting Regulations. This enables the heatsink to be easily removed from the lower assembly thereby allowing easy access to the LED board and electronic components. The LED board can then be easily removed and replaced with a new LED board which includes the electronic components. When the new LED board is fitted and the heatsink re-attached to the lower assembly the lower assembly can be reboxed and resold to the original manufacturer’s specification of light output, efficiency and life span. The original LED board can be sent to a specialist reclaim facility for recycling. So with this design all of the components in the original downlight product, apart from the old LED board, can be continuously reused. In another aspect of the invention there is provided a light fitting comprising a first unit including a fire resistant housing adapted to be mounted within an aperture in a partition and secured to the partition; the first unit including means to releasably support a second unit, the second unit comprising a solid state light source and a heat sink for dispersing heat away from the solid state light source; and wherein the heatsink is releasably attached to the solid state light source. The heatsink may be fastened to the solid state light source using one or more screw and / or bolt fasteners. Alternatively or additionally, the heatsink may be clamped to the solid state light source. The use of a non-adhesive thermal interface material ensures good thermal conduction between the solid state light source and heatsink by minimising, if not eliminating, air gaps or spaces from the interface area between the solid state light source and heatsink. The first unit may comprise means to be connected to an electrical power supply and is adapted to supply electrical power from the supply to the second unit to power the solid state light source. The second unit comprise a circuit board that carries the solid state light source. The second unit may comprise circuitry configured to operate the solid state light source from an alternating current electrical power supplied from the first unit. The circuitry may be carried by the circuit board. Typically, the thermal interface material will lie directly between and be in direct contact with each of the heat sink and the circuit board carrying the solid state light source and thus may function to minimise if not eliminating, air gaps or spaces from the interface area between the circuit board and the heatsink. The first unit may comprise clamping means to clamp the first unit against a first and second sides of the partition The first unit and second unit may be adapted to be releasably coupled together through a twist lock fitting through which, by rotation of the second unit relative to the first unit, the second unit can be coupled or uncoupled to / from the first unit whilst the first unit is secured to the panel, and optionally through which, when the first and second units are coupled, the first unit provides an electrical power supply to the second unit to power the solid state light source. The second unit may comprise a bezel. The bezel may carry and / or define one or more reflective surfaces or lens to shape and / or direct light emitted from the light source. The bezel may function to provide a cosmetic cover that conceals the aperture in the partition when the second unit is mounted to the first unit. The heatsink may be mounted to an opposite facing side of the circuit board to the light source. The bezel may carry the circuit board. The heat sink may be secured directly to the bezel. The circuit board may be retained between the heat sink and the bezel. The circuit board may be retained to the bezel by virtue of its retainment between the heatsink and the bezel. With this arrangement, once the heatsink is removed, the circuit board can be separated from the bezel, a new replacement circuit board put in its place, and the heatsink reattached to the bezel. The second unit, replete with replacement circuit board, can then be remounted to the first unit, which has remained in place above the partition. According to another aspect of the invention there is provided a second unit of any claim 1-11 comprising a solid state light source and a heat sink for dispersing heat away from the solid state light source; and wherein the heatsink is releasably attached to the solid state light source. The second unit may comprise a bezel holding the circuit board carrying the solid state light source. According to another aspect of the invention there is provided a method of reconditioning the second unit, the method comprising detaching the heatsink from the solid state light source, replacing the existing solid state light source with a new solid state light source, and reattaching the heatsink. The method may further comprising, following reattaching the heatsink, mounting the second unit to a first unit; replacing the circuit board a first unit including a fire resistant housing adapted to be mounted within an aperture in a partition and secured to the partition; the first unit including means to releasably support a second unit, the second unit comprising a solid state light source and a heat sink for dispersing heat away from the solid state light source; and wherein the heatsink is releasably attached to the solid state light source. The invention will now be described by way of example with reference to the following Figures in which: Figure 1 is side partial cross section view of a fire rated downlight; Figure 2 is a partial cross section view of a variant embodiment of the lower assembly; Figure 3 is a partial cross section view of a second variant embodiment of lower assembly; and Figure 4 is a partial cross section view of a third variant embodiment of lower assembly. The upper assembly 6 is made up of a fire protective housing 1 which is preferably made from steel so as to prevent fire from reaching the cavity above the partition 2 through the aperture in the partition 2 occupied by the fire protective housing 1. The fire protective housing 1 is secured to the partition 2 by a clamping arrangement 3 which is preferably made from steel. Inside the fire protective housing 1 is an annulus 5 that is attached to the inside face of the fire resistant housing 1. This annulus 5 provides the means by which the lower assembly 7 is releasably attached to the upper assembly 6. The annulus 5 also provides the lower assembly 7 with electrical supply via an extension of cable 4 to the annulus 5. The lower assembly 7 is made up of a heatsink 9 that is attached to the LED board 10, preferably by screws or clamps, is designed to withdraw heat generated by the LED board 10 so as to keep the temperature of the LED below the threshold Tj temperature. This ensures that the LED performs to the manufacturer’s specification. The LED board 10 also contains all of the necessary electrical and electronic components to drive the LED efficiently. These LEDs and LED boards 10 with the micro electronic components are currently available on the market and are compact and slimline. Mounted on the LED board 10 are the bayonets 8 which make mechanical and electrical contact between the lower assembly 7 and the equivalent bayonets 8a mounted to the annulus5 that is fixed to the inside face of the fire resistant housing 1. Attached to the LED board 10 is a bezel 11. The functions of the bezel 11 is to firstly support the optics that shape the light emitted by the LED board 10 and this shaping of the light can be done by lenses or by a reflecting surface on the inside surface of bezel 11 and secondly the bezel 11 provides a cosmetic cover over the aperture in the partition 2. This design of the lower assembly 7 allows the lower assembly 7 to be fitted and replaced by a lay person without the use of tools. Since the heatsink 9 is attached to the LED board 10 by screws or clamps the replaced lower assembly 7 can then be easily disassembled during the recycling process. As recommended by the European Single Lighting Regulations. Good thermal contact between the heatsink 9 and the LED board 10 is ensured through provision of a non-adhesive thermally conductive compressible material 100 located directly between, and in direct contact with each of the LED board 10 and heatsink 9. Since the material 100 is non adhesive, namely it does not fasten the heatsink 9 to LED board 10 through an adhesive bond (chemical or mechanical), the two can be readily separated by releasing the screws or clamps, allowing the LED 10 to be replaced once it fails, thus avoiding the need to discard both the LED board and heatsink 9. Figure 2 illustrates a variant example embodiment of lower assembly 70 adapted to be mounted to first unit 6. The lower assembly 70 comprises a bezel 71 holding a circuit board 72 having a first facing side 72A carrying a solid state light source 73, e.g. a semiconductor light emitting diode, organic light emitting didoes and / or polymer light emitting diode. A heat sink 74 is mounted onto an opposite facing side 72B of the board 72 for drawing away heat generated by the circuit board 72. The heatsink includes fins 74A to increase the surface area of the heatsink to improve dissipation of heat into the surrounding air. The heat sink 74 is releasably fastened to the circuit board 72 by means of one or more threaded fasteners 75, e.g. screws or bolts, which pass through apertures 74B, 72C of the heatsink 74 and board 72 respectively and are secure into the bezel 71. In this way the heatsink 74 is urged against the board 72 to maintain good physical contact between the two to ensure a good conductive path for heat transfer from the board to the heatsink is maintained. Additionally, by this arrangement the circuit board 72 is sandwiched between the heatsink 74 and bezel 71 and therefore does not require to be fastened or otherwise attached to the bezel by independent means (though it may). This means that following removal of the heat sink 74, the circuit board can also be readily separated from the bezel 71 when it is wished to replace the circuit board 72, e.g. when refurbishing the lower assembly following failure of the light source or associated circuitry. As with the examples of Fig 1, good thermal contact between the heatsink 74 and the circuit board 72, is ensured through provision of a non-adhesive thermally conductive compressible material 100 located directly between the heatsink 74 and circuit board 72 which allows for ready separation of the two should the circuit board 74 fail. Examples of suitable material for the thermally conductive compressible material 100 include a high thermal conductive graphite sheet or membrane, such as, for example, supplied by Tanyuan Technology Development Co. Ltd. under the name TGSTM, or T-GON-810 supplied by DK Thermal. Alternatively, a non-adhesive thermal grease or thermal paste may be used so long as it does not markedly hinder the separation of the circuit board 72 from the heatsink 74 and mounting of a new circuit board to the heatsink 74. In a variant, the fasteners 75 may fasten the heatsink 74 to the circuit board 72 without passing into the bezel 71. In a further variant the fasteners 75 may fasten the heatsink 74 directly to the bezel 71 without passing into or through the circuit board 72. Mounted to the circuit board 72 are bayonet pins 76 forming part of a twist lock fitting for releasably fastening the lower assembly to the upper assembly, and through which electrical power is supplied from the upper assembly to the circuit board 72 to power the solid state light source 73. The bezel also carries optical elements 77, e.g. one or more of a reflective cone, and / or lenses for shaping and / or directing the light emitted from the solid state light source. The circuit board 72 carries, in addition to the LEDs 73, driver circuitry configured to modify an input mains power supply, namely an alternating current at between 220V -240V, to a form suitable to drive the LEDs 73. As such the circuitry may comprise one or more of a rectifier, and voltage level changing component or circuitry. Figure 3 illustrates another variant of lower assembly 80 which differs from that of Fig 2 in that the heatsink 74 is releasably retained to the circuit board 72 and bezel 71 by clamping means, in this example a rotatable spring clip 81, though other types of clamping means may be used instead, such as example, a swivel clamp. The spring clips 81 extend through the circuit board 72 and anchored in the bezel 71. They are rotatable relative to the about a vertical axis, from the view point of Fig 3, between an engaged position, as illustrated in Fig 3, in which a lateral arm 81A of the clamp lies directly over the top of the heat sink 74 to provide a downward clamping force onto the heatsink 74 to urge it against the circuit board 72, and a disengaged position in which the lateral arm 81 are swivelled away from the heatsink 74 allowing it to be lifted up away from the circuit board 72. Figure 4 illustrates a further variant of lower assembly comprising a variant heatsink 91 comprising, instead of fins, a baseplate 91A from which extend columns 91B. Heatsinks 91 of this form are able to provide improved heat dissipation compared with the fin variety of Figs 2 and 3. The heatsink 91 is releasably fastened to the circuit board 72 by threaded fasteners 75, e.g. screws or bolts, which pass through apertures 91C in the base plate, and aperture 72C of the board 72 and are secure into the bezel 71. 5 Possible variants to the embodiments of Figs 2-4 include: The lower assembly may further include a releasably attachable decorative bezel. Other means to provide a twist lock attachment with the upper assembly may be employed, e.g. that described in GB2514685. 10 Means other than a twist lock fitting may be used to connect the upper and lower assemblies, though for most practical purposes the twist lock is likely to be preferred. 15

Claims

1. A light fitting comprising a first unit and a second unit; the first unit including a fire resistant housing adapted to be mounted within an aperture in a partition and secured to the partition;the first unit including means to releasably support the second unit, the second unit comprising a solid state light source, and a heat sink for dispersing heat away from the solid state light source; wherein the heatsink is releasably attached to the solid state light source; and wherein a non-adhesive thermal interface material lies directly between the solid state light source and the heatsink.

2. A light fitting according to claim 1 wherein the heatsink is fastened to the solid state light source using one or more screw and / or bolt fasteners.

3. A light fitting according to claim 1 or 2 wherein the heatsink is clamped to the solid state light source.

4. A light fitting according to any previous claim wherein the first unit comprises means to be connected to an electrical power supply and is adapted to supply electrical power from the supply to the second unit to power the solid state light source.

5. A light fitting according to claim 4 in which the second unit comprises circuitry configured to operate the solid state light source from an alternating current electrical power supplied from the first unit.

6. A light fitting according to any previous claim wherein the first unit comprises clamping means to clamp the first unit to the partition.

7. A light fitting according to any previous claim wherein the first unit and second unit are adapted to be releasably coupled together through a twist lock fitting through which, by rotation of the second unit relative to the first unit, the second unit can be coupled or uncoupled to / from the first unit whilst the first unit is secured to the partition.

8. A light fitting according to any previous claim wherein the second unit comprises a bezel holding the light source, which optionally conceals the aperture in the partition when the second unit is mounted to the first unit.

9. A light fitting according to any previous claim wherein when the second unit is mounted to the first unit, the second unit sits at least partially within the housing of the first unit.

10. A light fitting according to any previous claim wherein the non-adhesive thermal interface material comprises a graphite sheet.

11. A second unit of any claim 1-9 comprising a solid state light source and a heat sink for dispersing heat away from the solid state light source; and wherein the heatsink is releasably attached to the solid state light source.

12. A second unit of claim 10 further comprising a bezel holding a circuit board carrying the solid state light source.

13. A second unit of claim 11 wherein the bezel defines and / or carries one or more reflective surfaces and / or lens for shaping and / or guiding light from the solid state light source.

14. A method of reconditioning the second unit of any previous claim, the second unit the second unit comprising a solid state light source, and a heat sink for dispersing heat away from the solid state light source; wherein the heatsink isreleasably attached to the solid state light source; and wherein a non-adhesive thermal interface material lies directly between the solid state light source and the heatsink; and the method comprising detaching the heatsink from the solid state light source, replacing the circuit board and reattaching the heatsink.

15. A light fitting comprising a first unit including a fire resistant housing that is adapted to be mounted within an aperture in a partition and secured to a second side of a partition said housing to be made of parts with a long usage life so as to remain in situ for the life of the partition and the means to releasably support a second unit that contains a heat sink and a solid state light source and is positioned on a first side of the partition and wholly are partially sits within the fire resistant housing so that light from the solid state light source can pass into the space adjacent to a first side of the partition.

16. A light fitting according to claim 15 whereby the solid state light source is an LED.

17. A light fitting according to claim 15 or 16 comprising means to be connected to an electrical supply and wherein electrical power is supplied to the second unit through the first unit.

18. A light fitting according to any previous claim wherein the first unit comprising clamping means to clamp the first unit against a first and second sides of the partition.

19. A light fitting according to claim 18 comprising clamping members arranged when installed to rest against the second side of the partition.

20. A light fitting according to claim 19 wherein the clamping members are mounted to the fire resistant housing21. A light fitting according to claims 18, 19 or 20 wherein the first unit is secured to the partition through a clamping action between the clamping members on the second side of the partition and the fire housing rim on the first side of the partition.5 22. A light source according to any claim 15-21 comprising the second unit whichcomprises a bezel in which the light source is mounted, the bezel having means for mounting the second unit to the first unit and being arranged when so mounted to wholly cover the exposed face of the first unit.

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