AU2013203425B2 - A Floodlight - Google Patents

Abstract

Abstract: A floodlight comprising an enclosure adapted to contain a plurality of banks of LEDs, at least one driver for the 5 LEDs positioned remote from the LEDs, the enclosure including a heat sink and air vents positioned between the banks of LEDs and the driver wherein heat generated by the LEDs and driver draws air into the enclosure past the heat sink to exit through the air vents to cool the floodlight. 4238966_1 (GHMatters) P91385.AU.1 10/04/13

Description

- 1 A FLOODLIGHT Introduction This invention relates to floodlights and especially 5 though not exclusively floodlights for use in the mining industry. Background of the Invention The mining industry demands floodlights with ever 10 increasing light outputs. These days many floodlights incorporate light emitting diodes (LEDs) and operate on a comparatively low DC voltage, such as 24 volts. A problem of using multiple series of LEDs is the heat that is generated from the LEDs, LEDs have to operate between 15 temperatures of -40 0 C and 70 0 C. The LEDs are expected to have an operating life of approximately 50,000 hours. The operating life of an LED is substantially reduced in high temperature environments and thus the thermal management of a light incorporating LEDs is critical. 20 The light also needs to have the desired optics in terms of direction concentration, and uniformity of the light. LEDs require electronic drivers which tend to produce electronic noise, which can be detrimental to other electronic equipment operating in the vicinity. There is 25 also a need for floodlights of this kind to be rugged and able to withstand extremes of temperature, shock and corrosion. It is these issues that have brought about the 30 present invention. Summary of the Invention In accordance with one aspect of the present invention there is provided a floodlight comprising an 35 enclosure adapted to contain a plurality of banks of LEDs, at least one driver for the LEDs positioned remote from the LEDs, the enclosure including a heat sink and an 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14 - 2 air vent positioned between the banks of LEDs and the driver wherein heat generated by the LEDs and driver draws air into the enclosure past the heat sink to exit through the air vent to cool the floodlight. 5 Preferably each bank of LEDs is position beneath a TIR lens and an outer lens covers the TIR lens. The heat sink may comprise a series of spaced fins on 10 the rear of the enclosure. In a preferred embodiment the enclosure has brackets on either side pivotally secured to an arm structure adapted to be located on the end of a post or mast. 15 Description of the Drawings An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: 20 Figure 1 is a perspective view of a floodlight, Figure 2 is a rear elevational view of the floodlight, Figure 3 is a side elevational view of the floodlight, 25 Figure 4 is a plan view of the front of the floodlight with some components removed, Figure 5 is a plan view of the front of the floodlight illustrating a shield covering circuit boards, Figure 6 is a schematic illustration of a lens 30 arrangement of the floodlight, Figure 7 is a perspective view of a TIR inner lens, Figure 8 is a partial section through the floodlight illustrating the inner and outer lenses, Figure 9a is a cross sectional view of the 35 floodlight, Figure 9b is an enlargement of the cross section taken within the circle shown in Figure 9a, 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14 - 3 Figure 10 is an enlarged plan view of the floodlight illustrating one corner of the light, Figures 11a and lb are respectively side and plan views of the floodlight illustrating airflow through the 5 floodlight, Figure 12 is a schematic view of the floodlight taken from the side showing airflow, and Figure 13 is a cross sectional view of part of one side of the floodlight showing mounting of the floodlight 10 to a support bracket. Description of an Embodiment The floodlight of an embodiment of the present invention provides 20,000 lumens of light on a 24 volt DC 15 supply using approximately 280 watts. The floodlight has an operating life of 50,000 hours and is designed to operate successfully in a mining environment in temperatures of 40 0 C to 70 0 C. The light is approximately 10kg in weight yet sufficiently robust to withstand the 20 shock loads and other physical extremes that are common place in mining environments. The floodlight 10 shown in the accompanying drawings, essentially comprises a housing 11 moulded in aluminium 25 to support banks of LEDs and drivers for the LEDs. The LEDs including appropriate optics to control the output of the floodlight. Either side of the housing 11 is secured to a support structure which is in turn attached to a mast or post. 30 As shown in Figures 1 to 3, the housing 11 comprises a substantially rectangular enclosure 12 defined by an upturned skirt 13 with slightly rounded corners. The front 14 of the housing defines the open enclosure 12 and 35 the rear face 15 of the housing is provided with a series of parallel spaced fins 16 that operate as a heat sink to cool the assembly in use. 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14 - 4 As shown in Figure 2 elongate brackets 20, 21 are bolted to each side of the rear 15 of the housing 11. Each brackets 20, 21 is in turn screwed to an arm 22, 23 that 5 is pivotally screwed to the bracket 20, 21 via a circular plate 24 at one end of the arm 22, 23. The lower end 25 of each arm 22, 23 merges with a mount 26 that extends along one edge of the housing 11. The mount 26 can be attached to a mast or post (not shown). 10 As shown in Figures 4 to 5, the enclosure 12 defined by the housing 11 supports four banks 30, 31, 32, 33 of LEDs 50 spaced in pairs along the longer sides of the enclosure 12. Each bank 30, 31, 32 or 33 of LEDs 15 comprises a circuit board 38 supporting fourteen LEDs 39 in two spaced rows. A plug 45 at one end of each board 38 supplies power to the LEDs 50. Each board 38 is held to the housing by four spaced screws 46. The space between the banks of LEDs is partially filled by a pair 20 of drivers 34, 35 in the form of printed circuit boards that are positioned centrally of the space with open heat dissipation channels 40, 41 running in a parallel spaced apart manner between the banks of LEDs 30 to 33 and the drivers 34, 35. The shorter sides of the rectangle 25 enclosure 12 incorporates the wiring, plug and socket arrangements between the drivers and the support boards for the LEDs. The drivers 34, 35 include electrical componentry to step down and rectify the input power to 24 volts DC. 30 As shown in Figure 5 a metal shield 47 that is an EMC shield is positioned to cover the drivers 34, 35. As shown in Figure 1 the spaces at either side of the enclosure which locates the wiring and the shield are 35 covered by an H shaped outer cover 51. A single outer lens 52, 53 extends across each pair of LED arrays as shown in Figure 1. 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14 -5 Optics The optics of the floodlight 10 are shown with 5 particular reference to Figures 6 to 8. As mentioned above each bank of LEDs comprises fourteen spaced LEDs in two spaced rows of seven. A lens assembly 60 is positioned over the LEDs and an outer lens 52 or 53 is positioned over the adjacent banks of LEDs to provide the 10 closed off finish as shown in Figure 1. As shown in Figures 6 and 7 the inner lens 60 is a total internal reflection lens (TIR). A rectangular moulded plastics tray 61 has two rows of seven lens 62 located in spaced parallel rows. The lens have a free-form formation with 15 the larger end 64 at the top of lens 62 and the smaller inner end 65 position above the LED 50. As shown in Figure 6 the light emanating from the LED 50 is reflected and refracted on free-form surfaces of the lens to exit as a substantially parallel series of beams. The outer 20 lens 52, 53 is transparent plastic with a substantially planar outer surface 54 and a formed undersurface 55. The formed undersurface 55 causes a refraction of the beams to assume the outward spread shown in Figure 6. The rectangular tray 61 that constitutes the TIR lens 60 25 has four legs 66 in opposed corners to facilitate attachment to the circuit board supporting the LEDs 50. The outer lens 52, 53 is a single rectangular piece that covers 2 banks of LEDs with radiused edges 57 on the top, bottom and sides as shown in Figure 1. The mounting of 30 the TIR lens 61 and LED circuit board to the housing 11 is as shown in Figure 9B. The lens 61 is held to the circuit board 38 and housing 11 by screws 65 that extends into a recess 66 position directly over one of the cooling fins 16 to ensure that the screw and the 35 associated componentry causes minimum airflow disturbance. 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14 -6 Airflow As described above the rear of the housing 11 has a series of parallel fins 16 extending from the top to the 5 bottom and across the longer sides of the housing. The enclosure has two parallel open spaces 40, 41 on the front face between the banks 30-33 of LEDs 50 and drivers 34, 35. The fins 16 at the rear of the housing 11 extend across the base of these open spaces 40, 41 as shown in 10 Figures 4 and 5. The heat generated by the LEDs 50 as well as the drivers 34, 35 causes air to be drawn into the rear of the enclosure 12 past the fins 16 to escape in an upward direction as shown in Figure 4 through the open channels 40, 41 which act as air vents. The 15 separation of the LEDs 50 from the heat generated from the drivers 34, 35 is critical to ensure satisfactory airflow as shown in Figures 4, 11a and lb. The LEDs 50 and the circuit board 38 constitute a heat source region which is separated from the driver board 34, 35 region by 20 the air vents 40, 41 with critical flow geometry. The air vents allow sufficient airflow over the cooling fins 16 on heat sink in all orientations of the floodlight 10 from horizontal to 20' from vertical as shown in Figure 11a. This arrangement provides optimum cooling even in a 25 still air environment with the heat of the LEDs 50 and circuit board 38 drawing air into the unit. A view of the airflow from above can be seen in Figure lb with the air coming in from either side of the rear, flowing through the unit 10 past the air vents 40, 41 and taking 30 heat away from the LEDs 50 and LED circuit boards assembly 38 as well as the printed circuit boards assembly 38 that constitute the drivers 34, 35. The heat sink at the rear of the housing 11 has an important role to also draw heat off the LED boards 38 and printed 35 circuit boards 34, 35 as shown in Figures 4 and 5. The fins 16 are positioned directly behind the LEDs 50 to provide the shortest and direct path of conduction of 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14 - 7 heat away from the LEDs 50 as shown in Figures 9a and 9b. Structural features 5 The floodlight 10 as described above is designed to be particularly robust so it can operate satisfactorily in hot, dirty environments. The position of the screws 46 that hold the circuit boards 38 of each LED bank 30-33 are equally spaced to ensure an even force distribution. 10 The join between the arms 22, 23 and the bracket 20, 21 at the rear of the housing is positioned as close to centre of gravity as possible to reduce moments that would be caused by high shocks forces. The housing 11 inclination relative to the mast or post is adjustable by 15 turning the brackets 20, 21 on the circular plate 24 and then locking the plate 24 is the desired position by the tightening up a screw 29 that can be located in spaced slots 28 around the periphery of the plate 24, see Figure 3. The wiring 70 for the light extends through an 20 aperture 71 in the centre of the rear of the housing 11 and the plug and socket arrangements that couple the printed circuit boards to the LEDs 50 to the drivers 34, 35 and the associated wiring are designed to be robust and hard wearing. 25 A further mounting feature is illustrated in Figure 13 whereby a stainless steel bolt 75 is fitted through the front of the housing 11 into the base of the housing from the inside of the enclosure 12 to engage a nut 76 30 and washer 77 at opposite ends of each bracket 20, 21. A rubber dampening bush 78 is located under the head of each bolt 75 to dampen vibration and also acts as an insulator against bi-metallic corrosion caused by the bracket 20 and the housing 11 being of dissimilar metals. 35 In the claims which follow and in the preceding description of the invention, except where the context 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14 - 8 requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated 5 features but not to preclude the presence or addition of further features in various embodiments of the invention. 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14

Claims (16)

1. A floodlight comprising an enclosure adapted to contain a plurality of banks of LEDs, at least one 5 driver for the LEDs positioned remote from the LEDs, the enclosure including a heat sink and an air vent positioned between the banks of LEDs and the driver wherein heat generated by the LEDs and driver draws air into the enclosure past the heat sink to exit 10 through the air vent to cool the floodlight.

2. The floodlight according to claim 1 wherein each bank of LEDs is positioned beneath a total internal reflection (TIR) lens array and an outer lens covers 15 the TIR lens array.

3. The floodlight according to either claim 1 or claim 2 wherein the heat sink comprises a series of spaced metallic fins on the rear of the enclosure. 20

4. The floodlight according to any one of the preceding claims wherein the enclosure has brackets on either side pivotally secured to an arm structure adapted to be located on the end of a post or mast. 25

5. The floodlight according to any one of the preceding claims wherein the banks of LEDs, air vent and driver are mounted in a single plane. 30

6. The floodlight according to any one of the preceding claims wherein the banks of LEDs are positioned on either side of two drivers with air vents between the drivers and the LEDs. 35

7. The floodlight according to claim 6 wherein the air vents are two parallel open channels.

8. The floodlight according to claim 7 where the drivers are positioned alongside each other and between the 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14 - 10 parallel air vents.

9. The floodlight according to any one of the preceding claims wherein each bank of LEDs comprises spaced LEDs 5 on a circuit board.

10. The floodlight according to any one of the preceding claims wherein the light output is between 0.1 and 0.2 watts per lumen. 10

11. The floodlight according to claim 10 wherein the light output is 0.14 watts per lumen.

12. The floodlight according to any one of the preceding 15 claims wherein the light output is between 50 and 100 lumens per watt.

13. The floodlight according to any one of the preceding claims wherein the light output is 71.4 lumens per 20 watt.

14. The floodlight according to any one of the preceding claims wherein the floodlight has an operating life of greater than 50,000 hours and is designed to operate 25 at temperatures ranging between -40 0 C to 70 0 C.

15. The floodlight according to any one of the preceding claims wherein the driver comprises a printed circuit board supporting electrical componentry to step down 30 and rectify the input power to 24 volts DC.

16. The floodlight substantially as herein described with reference to and as illustrated in the accompanying drawings. 35 5859766_1 (GHMatters) P91385.AU.1 TERUNI 15/10/14