II AUSTRALIA Patents Act 1990 WEIDMULLER PTY LTD COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: Lighting assembly The following statement is a full description of this invention including the best method of performing it known to us:- 2 Lighting assembly Field This disclosure relates, generally, to a lighting assembly and, more particularly but not necessarily exclusively, to a lighting assembly for use on a vehicle such as a locomotive. 5 Background At present lights, commonly referred to as ditch lights, are fitted to the front of locomotives to light sides of the railway. The ditch lights are mounted at a level above a bumper bar of the locomotive. 10 Additional lights, known as marker lights, are mounted above the cabin and usually emit a coloured light such as a red light. The illumination source of such ditch lights and marker lights is usually an incandescent light bulb. Such incandescent light bulbs have a relatively short life necessitating regular replacement which increases maintenance costs and downtime of 15 the locomotive. In addition the incandescent light bulbs generate a large amount of heat and, therefore, particularly due to the location of the ditch lights, there is a risk that passerby could bum themselves on such lights. Should the incandescent light bulb fail in use, there is a total loss of illumination which could have adverse consequences. Still further, the ditch lights and marker lights cannot be interchangeably used 20 due to the different coloured light emitted by the marker lights. Summary In one aspect, there is provided a lighting assembly which includes a one-piece housing defining a recess in which an illumination source is 25 receivable, the housing incorporating a heat dissipation arrangement and the recess defining an opening through which the illumination source is visible, in use; a substantially transparent cover member attachable to the housing to cover the opening of the recess; and a sealing arrangement interposed between the housing and the cover member to 30 inhibit the ingress of moisture and foreign material into the recess of the housing. The lighting assembly may include the illumination source, the illumination source being a solid state illumination source comprising a plurality of light emitting diodes (LEDs) driven by an associated driver circuit, each LED of the array comprising an LED element received in a lens member. All the LEDs of the array may be of the 3 same colour or one group of the LEDs may be of one colour with the LEDs of a second group being of a different colour. In the latter case, the groups of LEDs may be switchable. Further, the lighting assembly may include a load distribution element mounted 5 to the cover member, the load distribution element equalising a load applied to the sealing arrangement and inhibiting the application of stresses to the cover member. The cover member may be of a synthetic plastics material such as an engineering plastics material. As an example, the cover member may be a polycarbonate. The load distribution element may be a ring of a metal material which fits over 10 the cover member and is secured to the housing by suitable fasteners. The ring may ensure that the fasteners do not apply localised, concentrated loads to the cover member. The housing may be formed from a piece of metal material. The material may be aluminium and the aluminium may be machined to form the housing. 15 The heat dissipation arrangement of the housing may comprise a heat sink having a plurality of spaced, laterally extending fins, the fins being shaped to facilitate insertion of the housing into a receiving zone of an existing structure without the requirement to modify the receiving zone. More particularly, a fin at an operatively rear region of the housing may have a smaller width dimension than the remainder of 20 the fins. In the case of a circular housing, the width dimension of the heat sink fins is a diameter of the fins. In the case of a square or oblong housing, the width dimension of the heat sink fins may be a diagonal of the fins. Brief description of drawings 25 In the drawings, Fig. I shows a plan view of an embodiment of a lighting assembly; Fig. 2 shows a side view of the lighting assembly; Fig. 3 shows a plan view of a driver circuit of an illumination source of the lighting assembly; 30 Fig, 4 shows a rear view of the lighting assembly; Fig. 5 shows a plan view of the lighting assembly with the illumination source omitted; and Fig. 6 shows a sectional side view of the lighting assembly taken along line VI VI in Fig. 5. 35 4 Detailed description of exemplary embodiment In the drawings, reference numeral 10 generally designates an embodiment of a lighting assembly. The lighting assembly 10 comprises a one piece housing 12 defining a recess 14 within which an illumination source 16 is received. The housing 5 12 includes a heat dissipation arrangement 18. A substantially transparent cover member 20, shown most clearly in Fig 6 of the drawings, is removably attachable to the housing 12 to cover an opening of the recess 14. A sealing arrangement 22 (Fig 6) is interposed between the housing 12 and the cover member 20. The housing 12 is of machined aluminium and the heat dissipation arrangement 10 18 is integrally formed with the housing 12 as a one piece unit. The lighting assembly 10 is intended to be used on a locomotive as either a ditch light to light sides of the railway on which the locomotive travels or as a marker light. It will be appreciated that a ditch light is mounted above a bumper bar of the locomotive while the marker light is mounted above the cabin of the locomotive. 15 The illumination source 16 comprises a plurality of lensed light emitting diodes (LEDs) 24. Each LED 24 comprises a light emitting diode element 26 mounted in a lens 28 to focus light emitted by the LED element 26. As illustrated, six such LEDs 24 are provided mounted in a circumferentially spaced arrangement in the recess 14 of the housing 12. The LEDs 24 are mounted on a 20 printed circuit board 30 received in the recess 14 of the housing 12. In the case of the ditch light, all the LEDs 24 emit a white light while in the case of the marker light, three of the LEDs 24 on one side of an operatively vertical plane emit a red light while the remaining three LEDs 24 emit a white light. These LEDs 24 may be switchable to switch which group of the LEDs 24 emit the white light and 25 which group of the LEDs 24 emit the red light. The LEDs 24 of the lighting assembly 10 have a luminous intensity of greater than 20,000 Cd. The LEDs 24 are driven by an externally mounted driver circuit 32 as shown in Fig 3 of the drawings. The driver circuit 32 includes an LED driver 34 having a driver input 36 and an LED output 38. The LED output 38 connects the driver 34 to the LEDs 30 24 via a cable 40 (Fig 2). Ingress to the recess 14 of the housing 14 for the cable is provided by an opening 42 (Fig 6) in the heat dissipation portions 18 of the housing 12. A sealing gasket 44 is mounted in the opening 42 to inhibit the ingress of moisture and foreign material into the recess 14 of the housing 12. The driver 34 of the driver circuit 32 is a constant current driver and is able to regulate the light emitted by the LEDs 24 35 independently of variations in the supply voltage.
5 The LEDs 24 of the lighting assembly 10 are able to be flashed without affecting the life of the illumination source 16. As indicated above, the cover member 20 is of a transparent material. More particularly, the cover material is of an impact resistant, transparent plastics material. 5 The cover member 20 is of a suitable engineering plastics material such as a polycarbonate which has the required impact resistance. In this regard, it is also to be noted that the housing 12 and the cover member 20 are designed to comply with the relevant shock and vibration standards for railway rolling stock. The assembly 10 therefore has sufficient vibration and shock resistance to comply with the relevant 10 international standard and, more particularly, the IEC 61373 standard. The cover member 20 is secured to the housing via a plurality of fasteners in the form of screws 46. To ensure that the screws do not impart localised stresses to the cover member 20, a load distribution element in the form of a metal ring 48 bears against an outer surface of the cover member 20. The ring 48 is of a stainless steel and 15 inhibits the application of stress to the cover member 20. The ring 48 also equalises a load applied to the sealing arrangement 22. With the provision of the removable cover member 20, the lighting assembly 10 is, effectively, modular and it is possible to replace internal components of the lighting assembly 10, such as the illumination source 16, while the lighting assembly 10 is 20 mounted in situ. The sealing arrangement 22 is designed to comply with the relevant international standards and ingress protection levels mandated by those standards. In particular, the sealing arrangement 22 is designed to comply with the IP66 ingress protection level standard. 25 In this regard, the sealing arrangement 22 comprises a first high integrity 0-ring 50 arranged outwardly of the screws 46 and a second high integrity O-ring 52 arranged inwardly of the screws 46. The metal ring 48, when the screws 46 are fastened into the housing 12, bear against the 0-rings 50 and 52 to effect sealing of the recess 14 to the required standard. 30 The heat dissipation arrangement 18 comprises a heat sink having a plurality of laterally extending fins 54. It is to be noted that an operatively rearmost fin 54.1 has a smaller width dimension than the remainder of the fins 54. In the illustrated embodiment, the housing 10 is of circular form so that the width dimension of the fins 54 is the diameter of the fins 54. The provision of the rearmost fin 54.1 having a 35 smaller width dimension than the remainder of the fins 54 facilitates retrofitting of the light assembly 10 into a socket of a structure (not shown) designed to incorporate a 6 ditch light or marker light, as the case may be, on the locomotive. Hence, the lighting assembly 10 can be retrofitted without any modifications being made either to the receiving socket or the housing 12 of the lighting assembly 10. To facilitate mounting of the assembly 10, the housing 12 includes a radially 5 outwardly extending flange 56. The flange 56 has mounting openings 58 through which suitable fasteners are receivable. In addition, openings 62 are defined in an operatively rear surface 60 (Fig 4) of the housing 12 through which fasteners are received to facilitate rear mounting of the housing 12 of the lighting assembly 10. The lighting assembly 10 has a number of benefits over a standard incandescent 10 light used as a ditch light or marker light. In particular, the lighting assembly 10 has much higher impact resistance than a standard incandescent light. This impact resistance can be upto ten times higher than that of a standard incandescent light. For example, the lighting assembly 10 has an impact resistance of over 200J whereas a standard incandescent light failed at less than 20J. 15 In addition, the lighting assembly 10 has very low temperature and is safe to touch. A maximum surface temperature of the lighting assembly 10 is of the order 65'C which is considerably lower than the equivalent incandescent light. Further, the lighting assembly 10, has a far lower power consumption than the standard incandescent light. Typically, the lighting assembly 10 has a power 20 consumption which is approximately 15% that of the standard incandescent light, the lighting assembly 10 having a power consumption of approximately 15W versus 100W for the standard incandescent light. Still further, the lighting assembly 10 has an ultra long life of approximately 30,000 to 50,000 hours as opposed to approximately 300 to 1,000 hours for a standard 25 incandescent light. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not 30 restrictive.