P/00/012 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: "A PORTABLE LIGHTING TOWER" The following statement is a full description of this invention, including the best method of performing it known to me/us: 1 A PORTABLE LIGHTING TOWER FIELD OF THE INVENTION This invention relates to a portable lighting tower. In particular, the 5 invention relates to a portable lighting tower which is energy efficient, compact and robust. BACKGROUND TO THE INVETION Portable lighting towers are commonly used to provide work light at 10 roadside works, mining and construction sites, emergency sites, events etc. Portable lighting towers generally comprise a water-cooled diesel engine driving an alternator supplying current to high voltage lighting in the form high-intensity discharge lamps such as metal halide lamps. The metal halide lamps are typically 1000W lamps operating at 240V. Current 15 practice requires certified electrical personnel to service and maintain the high voltage lighting, engine, alternator and associated circuitry. The diesel engine generates all the energy required for lighting and necessarily consumes considerable fuel to power the high voltage lighting. The energy efficiency of the lighting tower is also affected by the efficiency of 20 the alternator. High voltage lighting can be fragile and often fails to withstand the vibrations from transporting the lighting towers or the industrial treatment encountered in industrial and mining applications. High intensity discharge lamps suffer from the cyclic effects of being turned on and off. 25 Portable lighting towers are required to be light and compact for easy transportation while still being powerful enough provide adequate lighting. There is a need for a portable lighting tower which is energy efficient, compact, robust or easy to maintain.
2 OBJECT OF THE INVENTION It is an object of the invention to overcome or at least alleviate one or more of the above problems and/or provide the consumer with a useful or commercial choice. 5 SUMMARY OF THE INVENTION In one form, although it need not be the only or indeed the broadest form, the invention resides in a portable lighting tower including: a combustion engine; 10 a permanent magnet direct current (DC) alternator driven by the combustion engine to output a direct current; and at least one high-power light emitting diode (LED) lamp powered by the direct current generated by the permanent magnet DC alternator. In another form, the invention resides in a portable lighting tower 15 including: an air-cooled diesel engine; a direct current (DC) alternator driven by the diesel engine to output a direct current; and at least one high-power light emitting (LED) lamp powered by the current 20 generated by the DC alternator. The current generated by the DC alternator is preferably at or below 60VDC and the LED lamp is configured to be powered by a current with a voltage at or below 60VDC. LED lighting of the lighting tower preferably comprises LED lamp arrays. 25 The portable lighting tower preferably includes a scissor mechanism having the LED lamp arrays mounted at a distal end region of the scissor mechanism. The invention extends to a portable lighting tower including a scissor lift mechanism having one or more lamps mounted at a distal end 30 region of the scissor lift mechanism. The portable lighting tower defined and described hereinabove provides an energy efficient lighting solution by combining an air-cooled 3 diesel engine, a permanent magnet DC alternator, and supplying power directly or through batteries to high-powered low-voltage DC LED lighting. BRIEF DESCRIPTION OF THE DRAWINGS 5 To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, wherein: Figure 1 is a schematic layout of a portable lighting tower in 10 accordance with one embodiment of the invention; Figure 2 is a schematic layout of another embodiment of a portable lighting tower in accordance with the invention; Figure 3 is diagrammatic side view of the lighting tower of Figure 1, showing a scissor lift of the lighting tower in a collapsed condition; 15 Figure 4 is another diagrammatic side view of the lighting tower, showing the scissor lift of the lighting tower in an expanded condition; Figure 5 is yet another diagrammatic side view of the lighting tower, with the LED lighting of the lighting tower rotated 900 with respect to its orientation in Figure 4; 20 Figure 6 is a diagrammatic side view of another embodiment of a lighting tower including a skid in accordance with the invention; and Figure 7 is a diagrammatic side view the lighting tower of Figure 6, showing the skid including accessories for handling and transportation of the skid. 25 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In this patent specification, words such as "comprises" or "includes" are not used to define an exclusive set of elements or method steps. Rather, such words merely define a minimum set of elements or method 30 steps included in a particular embodiment of the present invention. In the drawings, like reference numerals refer to like parts.
4 Figure 1 shows a schematic layout of a portable lighting tower 10 in accordance with one embodiment of the invention. The lighting tower 10 comprises an air-cooled diesel engine 12 connected to a permanent magnet DC alternator 14 to provide electrical current to high-powered low 5 voltage DC LED lighting 16 via a battery bank 18. A switchboard 20 of the lighting tower 10 is connected between the battery bank 18 and the LED lighting 16. The combination of the engine 12 and alternator 14 is hereinafter referred to as generator 15. A low-voltage DC circuit 11 connects the generator 15, the LED lighting 16, the battery 18 and the 10 switchboard 20. The generator 15 is typically a 2000Watts 24Volt DC PowerMaker Outback2.0 generator or a 2500Watts 24Volt DC PowerMaker Outback2.5 generator, commercially available from Watts 2 C Pty Ltd of Warana, Australia. The generator 15 comprises a Yanmar air-cooled diesel engine 15 12 that is directly coupled to a low-loss permanent magnet DC alternator 14. The permanent magnet DC construction of the alternator 14 provides high efficiency conversion of rotational energy from the engine 12 into DC electrical current. The alternator 14 uses a set of rectifiers (diode bridge) to convert AC to DC. The alternator 14 includes an assembly of 20 permanent magnets. The alternator 14 is connected to the engine 12 through a direct drive arrangement to reduce mechanical energy losses. Using a permanent magnet alternator has a big advantage over a DC motor because the alternator has no brushes to wear out. Also, a standard field-wound alternator requires power to energize a field, whereas the 25 permanent magnet alternator does not require any power to start generating, and is therefore more efficient than a comparable standard field-wound alternator. Air-cooled diesel engines have simple compact construction and are comparatively light weight when compared to water-cooled diesel 30 engines. The simplicity of air-cooled diesel engines makes them less prone to mechanical failure. Air-cooled diesel engines are also generally 5 more fuel efficient and consume less oil to comparable water-cooled diesel engines. The DC LED lighting 16 comprises three LED lamp arrays 22, but may comprise any suitable number of LED lamps or LED lamp arrays. 5 Each LED lamp array 22 optionally includes optics to focus light, scatter light, or provide a mixture of focussing and scattering as may be required. Suitable high-powered low-voltage DC LED lamp arrays for use in the lighting tower 10 include the CP96 high power LED array flood light manufactured by Coolon Pty Ltd of Oakleigh, Australia. The CP 96 flood 10 light has the following specifications: Luminous Flux: 8300 - 14000 Im LED Efficacy: <901m/w @ 25*C Power Consumption: 24VDC 320W Power Supply: 24VDC 320W 15 Current Consumption: 8.4A Max Max. Operating Voltage: 26VDC Min. Operating Voltage: 23VDC Another example of an LED lamp array is the Omega 24K commercially available through Southern Cross Auto Electrics and also 20 operating at a nominal operating voltage of 24VDC. Although the nominal operating voltage of the LED lamp arrays 22 is 24VDC, the Applicant envisages that any suitable LED lamp operating at a low voltage at or below nominally 60VDC will be suitable. It will be appreciated that the generator 15 and the LED lamp arrays 22 are 25 matched so that both operate at substantially the same DC voltage to eliminate electrical equipment and devices to regulate, rectify or transform the electrical current between the LED lighting 16 and the generator 15. The operational lives of LED lamps are much longer than comparable high intensity discharge lamps traditionally used in portable lighting towers. The 30 key strength of LED lamps is its reduced power consumption when compared to high-intensity discharge lamps and its low operational voltage. LED lamps provide light in a spectrum natural and familiar to 6 colours seen during the day and does not produce visible stroboscopic effects, thus reducing eye strain and improving safety in industrial and mining applications. The LED lighting 16 is powered from the battery bank 18, which is 5 in turn charged by the generator 15. The battery bank 18 comprises two 12VDC batteries connected in series to produce 24VDC. The battery bank 18 is additionally utilized for automatic electric starting of the generator 15. As such, the charge capacity or the battery bank 18, measured in amp hours, is adequate to the extent of providing sufficient 10 charge to require only intermittent operation of the generator 15. Automatic starting of the generator 15 is controlled from the switchboard 20. The switchboard 20 is configured to start the generator 15 based on time of day, battery bank 18 condition, or manually. The selection of the battery bank 18 may be such that it is sufficient for starting of the 15 generator 15 only, or be selected to be charged sufficiently to provide power to the LED lighting 16 for any number of hours without being charged by the generator 15. A typical selection would be for the battery bank 18 to be appropriately sized to provide some storage in the event of generator 15 malfunction and sufficient to electrically start the generator 20 15. The batteries of the battery bank 18 are preferably deep cycle maintenance free batteries. The battery bank 18 is housed in an enclosure or housing for environmental protection. The switchboard 20 includes electrical circuit protection devices and controls. The switchboard 20 is housed within an electrical cabinet to 25 maintain the electrical integrity of the electrical circuit protection devices and controls. The protection devices include circuit breakers, contactors, isolation switches, main switches, fuses, cable terminations and control equipment. The controls incorporate specific interlocks limiting unsafe operation of the lighting tower 10. The controls also include devices for 30 turning the LED lighting 16 and generator 15 on or off at preset conditions as discussed. Operation of the switchboard 20 to turn the LED lighting on 7 or off may be done manually, automatically, or the lighting tower 10 may include hardware for remote actuation of the controls. Figure 2 illustrates another embodiment of a portable lighting tower 100 in accordance with the invention. The portable lighting tower 100 5 comprises the same engine 12, generator 15, LED lighting 16, battery bank 18 and switchboard 20, but configured in a different way. In the lighting tower 100 the battery bank 18 is used solely for starting the generator 15 and not to power the LED lighting 16. The switchboard 20 is connected to the generator 15. 10 Figures 3 to 5 show the portable lighting tower 10 including a trailer 24 and a scissor lift mechanism in the form of a scissor lift 26. Although described with reference to lighting tower 10 of Figure 1, it will be appreciated that the lighting tower 100 can similarly include a trailer 24 and scissor lift 26. The scissor lift 26 is collapsible and extendable. The 15 scissor lift 26 is shown in a collapsed condition in Figure 3 and in an extended condition in Figures 4 and 5. The scissor lift 26 has a base 30 fixed to the trailer 24 and a distal end 32. The scissor lift 26 includes scissor arms 27 which are pivotally connected. Pairs of scissor arms 27 are stacked vertically. The LED 20 lighting 16 is mounted at a distal end region of the scissor lift 26. The LED lighting 16 may be positioned above or below the distal end 32 of the scissor lift 26. The LED lighting 16 includes a support bar 33 mounting the LED lighting 16 to the distal end 32 of the scissor lift 26. The orientation of the LED lighting 16 can be adjusted through rotating of the support bar 33. 25 Figure 5 shows the LED lighting 16 rotated 90 relative to the position of the LED lighting 16 depicted in Figure 4. The lighting tower 10 includes actuators (not shown) in the form of hydraulic rams, pneumatic rams or mechanical motors to displace the scissor lift 26 between the collapsed and extended condition. 30 In the extended condition the scissor lift 26 elevates the LED lighting 16 relative to the trailer 24. In the collapsed condition the lighting tower 10 is configured for transportation or storage. The Applicant 8 envisages that the scissor lift 26 can lift the LED lighting 16 higher without sacrificing stability when compared to traditional telescopic or hinged booms. The trailer 24 includes a housing 34 in which the engine 12, 5 generator 15, battery bank 18 and switchboard 20 is housed. The trailer 24 also includes a separate fuel tank 36 above the axle 38 of the wheels 40 of the trailer 24. The fuel tank 36 is selectively filled with diesel to supply fuel to the generator 15. The capacity of the fuel tank 36 may permit the lighting tower 10 to require refuelling hourly, weekly or between 10 service intervals. The improved efficiency of the lighting tower 10 allows for a relatively small capacity fuel tank 36 and extended periods between refuelling. The trailer 24 includes a trailer hitch 42 for towing the trailer between locations and stabilisers 44 for stabilising the trailer 24 when the lighting tower 10 is set up. 15 Figure 6 shows a lighting tower 200 which is the same as the lighting tower 10 described with reference to Figures 3 to 5, with the only difference being that the lighting tower 200 includes a simple skid 202 instead of a trailer. The same reference numerals are used to refer to features of the lighting tower 200 which are the same as the features of 20 the lighting tower 10. Figure 7 shows the skid 202 including push bars 204, forklift tine holes 206 and lifting points 208. The bars 204, holes 206 and lifting points 208 are all for ease of handling to transport the skid 202. The combination of the generator 15 and LED lighting 16 of the 25 present invention provides a compact lightweight lighting tower which is robust and fuel efficient. Compact and lightweight design is an important consideration for mobile or portable lighting solutions for industry applications like road construction and maintenance. The lighting tower 10, 100 of the present invention provides a highly efficient portable lighting 30 solution by using a fuel efficient diesel engine, energy efficient alternator and energy efficient lighting. The use of high-powered low-voltage DC LED lighting does not require certified electricians to maintain the lighting.
9 Furthermore, LED lighting is much more robust to withstand vibrations and do not suffer from the cyclic effects from on/off states. Using energy efficient LED lamps facilitates use of a comparatively small power source. The low-voltage DC circuit between the generator 15 and the LED lighting 5 16 further simplifies the maintenance requirements and circuit protection devices, making the said combination simpler, safer and more efficient. Throughout the specification the aim has been to describe the invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize 10 variations from the specific embodiments that will nonetheless fall within the scope of the invention.