AU2006252231B2 - Retractable covering system - Google Patents

Abstract

A covering system (100) provides a retractable covering for a structure (102), such as a pergola or veranda. The system (100) has a roof portion (103) that is normally open to the environment, and includes a substantially cylindrical shaft (104) having a central longitudinal axis (106) and a motor (108) with which the cylindrical shaft (104) is engaged such that, in use, the motor (108) is operable to rotate the shaft (104) about said longitudinal axis (106). The motor (108) is operably engaged with a guide (110) disposed upon or adjacent to the roof portion (103) of the structure, whereby the motor (108) is able to move transversely relative to the roof portion (103) along the guide (110) in a direction perpendicular to the longitudinal axis (106) of the shaft (104). A web of flexible material (114), a first edge (116) of which is fixed to the structure (102), has an opposing edge which is fixed to the cylindrical shaft (104). The covering system (100) has an open position wherein the web of flexible material (114) is substantially rolled around the cylindrical shaft (104) adjacent to the first edge, and a closed position wherein the web of flexible material (114) is unrolled from the shaft (104) to substantially cover the roof portion (103) of the structure, and is operable between said open and closed positions by operation of the motor (108) in corresponding opposed rotational directions. 122 102 124 10 4 -102 108 11 110 114, 116 t~13 1 13 0 11012 -

Description

pool Section 29 Regulation 3.2(2) AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: Retractable covering system The following statement is a full description of this invention, including the best method of performing it known to us: 1 RETRACTABLE COVERING SYSTEM FIELD OF THE INVENTION The present invention relates to covering systems for external structures, and more particularly to a motorised retractable covering system. 5 BACKGROUND OF THE INVENTION It is common, particularly in temperate and warmer climates, for many activities to be conducted outdoors. For example, during clement weather conditions many people find outdoor leisure activities, such as entertaining, barbecues and so forth, to be particularly appealing. In addition, various work 10 and labour-related activities may be conducted in an outdoor environment. Under some weather conditions it may be acceptable and desirable that the area in which outdoor activities are taking place be uncovered. For example, this may be so when the weather is fine but not excessively hot or sunny. However, in other conditions it may be desirable or even essential that cover be 15 provided, eg for shade or to keep rain off the area. Provision of shade as protection against the sun is particularly important in view of the known links between excessive exposure to sunlight and various skin cancers, especially in those regions of the world affected by depletion of the ozone layer. Accordingly, it is desirable to provide open structures, such as verandas, 20 pergolas, and other suitable structures, having roofs that may be easily opened or closed, depending upon the prevailing environmental conditions. Previously known arrangements for providing closable coverings include awnings and roofing systems employing rotatable louvres or slats. However, due to the need for a suitable cantilever arrangement, awnings are generally limited in their size 25 and location, and are often manually operated. Roofing systems employing rotatable louvres or slats are relatively expensive, and the cost increases significantly with the size of the area to be covered, due to the need for more panels. Additionally, rotatable louvres always provide some level of cover, even when rotated into a fully open configuration, and therefore cannot provide the 30 effect of an outdoor area that is wholly open to the environment. It is particularly desirable that a covering system be provided that is automated, that is simple to operate, that is able to cost-effectively provide a 2 retractable covering for a relatively large structure, and which maximises the entry of light, and thus the perception of being outdoors when fully open. There remains, therefore, a need for an improved retractable covering system for external structures such as pergolas and verandas, which mitigates 5 the limitations of known systems, or at least provides a useful and cost-effective alternative to such systems. It is accordingly an object of the present invention to provide such a retractable covering system. SUMMARY OF THE INVENTION In one aspect, the present invention provides a covering system providing 10 a retractable covering for a structure having a roof portion that is normally open to the environment, the system including: an at least cylindrical shaft having a central longitudinal axis; a motor with which the cylindrical shaft is engaged such that, in use, the motor is operable to rotate the shaft about said longitudinal axis; 15 a first guide disposed upon or adjacent to the roof portion of the structure with which the motor is operably engaged, whereby the motor is able to move transversely relative to the roof portion along the first guide in a direction perpendicular to the longitudinal axis of the shaft; and a web of flexible material, a first edge of which is fixed to the structure and 20 an opposing edge of which is fixed to the cylindrical shaft, the covering system having an open position wherein the web of flexible material is substantially rolled around the cylindrical shaft adjacent to a location on the structure at which said first edge of the web is fixed, and a closed position wherein the web of flexible material is at least substantially unrolled from the shaft 25 to at least substantially cover the roof portion of the structure, and being operable between said open and closed positions by operation of the motor in corresponding opposed rotational directions. The first guide is a rigid track or rail with which the motor is operably engaged so as to be slidable alongside the roof portion of the structure. The 30 motor is engaged with the first guide via a torsion arm. A system in accordance with the invention thus enables a web of material, such as cloth, shade mesh, plastic and so forth, to be automatically and retractably rolled over a roof of a suitable structure or framework, under the 3 operation of a motor, so as to provide a closable covering for the structure. The inventive system is readily adapted to provide a covering for structures of varying sizes, the width of the structure only being limited by the practical length of the cylindrical shaft and width of the flexible material, and the length of the structure 5 being limited only by the length of material that may reasonably be rolled around the cylindrical shaft in the closed position. Furthermore, since the covering material is fully retracted in the open position, it enables maximum entry of light into the structure. This feature may be particularly useful over grassed or other planted areas, to allow vegetation to receive sunlight for growth, while enabling 10 the cover to be closed as desired for other purposes, such as entertaining. Additionally, in regions in which strong winds, cyclones and/or hurricanes may occur, the ability to fully retract the cover enables wind-loading on the structure to be significantly reduced, thereby reducing the possibility of damage. A further advantage of the present invention is the substantial reduction in the number of 15 moving parts as compared with, for example, covering structures based upon rotatable louvres or slats. Embodiments on the invention may be used to provide waterproof cover against rain, and/or complete shade when closed, by using an impermeable web of flexible material, such as suitable cloth or plastic. For example, a tarpaulin 20 consisting of a PVC material having a weight of 650 g/m 2 may be used. Alternatively, a cover providing partial shade may be provided by using a web of flexible material consisting of a shade mesh. Generally, the first guide is required to provide a sufficiently rigid support for the motor, enabling it to move in a smooth and stable manner alongside the 25 roof portion during opening and closing of the cover. One end of the torsion arm may be directly engaged with the first guide, and the motor may be fixed to an opposing end of the torsion arm. Advantageously, the inclusion of a torsion arm prevents the motor housing from rotating when power is applied. 30 Furthermore, a torsion arm enables the motor to move vertically relative to the roof covering when in use, for example to accommodate variations in the 4 vertical position of the cylindrical shaft due to the shape of the structure and/or the varying diameter of the rolled web of material as it is unrolled over and retracted from the roof portion. It is further preferred that a tensioner be provided at one or both ends of 5 the cylindrical shaft, the tensioner applying a restoring force in the direction of the fixed first edge of the web of flexible material. Advantageously the magnitude of the restoring force should be small enough that it is easily overcome by the motor during closing of the covering system, but large enough to maintain tension during opening and closing of the covering system, so that the system operates 10 smoothly and without undesired unravelling of the web of flexible material from the cylindrical shaft. The tensioner may be, for example, an elastic cord or a spring. Alternatively, the tensioner may include a substantially inelastic cord, rope, cable or the like running over a pulley located near or beyond the location on the 15 structure at which the flexible material is attached, and having a counterweight attached to provide a suitable restoring force. Particularly preferred embodiments of the invention include a projecting stop disposed at an edge of the roof portion of the structure that is opposed to the fixed first edge of the web of flexible material, and arranged such that during 20 closure of the covering system the cylindrical shaft passes over the stop and is subsequently drawn back to bear against the stop by continuing rotation of the shaft which causes the web to fully unroll from the shaft and to commence rolling around the shaft in an opposing direction. A benefit provided by this preferred arrangement is that the web of material is drawn taut over the roof portion of the 25 structure, thereby facilitating run-off of rain and substantially preventing movement, such as rippling and/or flapping, of the covering web of material in windy conditions. Generally, therefore, the use of a projecting stop enables the cover to be held securely in place without the need for additional moving parts or more complicated mechanical controls. 30 As will be appreciated, the preferred arrangement employing a projecting stop also enables the simple release of the web of material, since reversal of the operating direction of the motor will cause the web to slacken and the shaft to roll back over the stop, thereby releasing the cover for closure.

5 In a particularly preferred embodiment, the projecting stop is a lock angle. Preferably the lock angle is located along a substantially vertical surface of the structure and below the upper surface of the roof portion, and projects in a substantially horizontal direction such that when closed the roof portion is fully 5 covered, and the cylindrical shaft is securely located beneath the covered roof level and bears against a lower surface of the stop. Overall, this particularly preferred arrangement provides for smooth operation, a neat appearance, and for complete covering of the roof portion if desired. The motor is preferably an electric motor, and may be powered, for 10 example, by a free-hanging cable of sufficient length to reach the motor at its most distant point. However, a preferred alternative powering arrangement includes conductive tracks or busbars in the first guide, with brush contacts being provided to conduct power from the busbars to the motor when the motor is located at any position along the first guide. 15 In some embodiments of the covering system, the motor is engaged with the cylindrical shaft at one end thereof, and a second guide is disposed upon or adjacent to the roof portion of the structure, and is engaged with an opposing end of the cylindrical shaft. While it is not essential for the operation of the invention that dual guides be provided for guiding both ends of the shaft, this arrangement 20 advantageously provides improved strength and/or stability of the covering system during use, particularly in adverse weather conditions such as high winds. The power source for the motor is preferably a high current supply, in order to provide sufficient power during opening and closing of the cover and especially during tightening of the cover against a projecting stop. For example, the motor 25 may require on the order of 100 ampere of direct current when under load during tightening of the cover. For reasons of safety and convenience it is preferable that the power supply to the motor be relatively low voltage, and be a DC supply. With these considerations in mind, preferred sources of power include car batteries. A supplemental mains supply may be used for charging of the battery, 30 and may either be permanently connected to maintain maximum charge in the battery, or may be periodically connected for recharging of the battery after use. Further advantages and preferred features of the invention will be apparent from the following description of a preferred embodiment, which is provided by 6 way of example only and without limitation to the scope of the invention as defined in the preceding statements and the claims appended hereto. BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described with 5 reference to the drawings, in which like reference numerals refer to like features, and wherein: Figure 1 is a schematic illustration showing a side view of a structure upon which is installed a covering system in accordance with one embodiment of the invention; 10 Figure 2 shows a perspective view of the covering system of Figure 1; Figures 3A and 3B illustrate an alternative embodiment of the invention which employs a second guide rail for improved strength and/or stability; Figures 4A, 4B and 4C illustrate a process of closing the cover according to preferred embodiments of the invention; 15 Figure 5 illustrates an arrangement for powering the motor of a covering system according to an embodiment of the invention; and Figure 6 illustrates a cross-sectional view of a first guide rail with conductive busbars according to an alternative arrangement for powering the motor of a covering system in accordance with an embodiment of the invention. 20 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Turning firstly to Figure 1, there is shown schematically a covering system 100 according to one embodiment of the present invention which has been fitted to a structure or framework 102. The structure 102 includes a roof portion 103 to which the covering system 100 is fitted. The structure 102 illustrated in Figure 1 25 includes a sloping roof portion 103, however it will be understood that the invention is applicable to structures having different forms, such as structures with flat roof portions. It will be appreciated, however, that a particular advantage of providing a sloping roof portion is to facilitate runoff, eg of rain water, when the covering system 100 is closed. 30 The structure or framework 102 is typically any convenient external structure, for example a veranda, patio covering or pergola. In accordance with the invention, the roof portion 103 of structure 102 is normally open to the environment, and accordingly in this normal state objects and/or persons located 7 beneath the roof portion 103 of the structure 102 are generally exposed to the environment, including sunlight and rainfall. For further clarity in the description of the embodiment 100 of the invention, Figure 2 shows the covering system 100 in a perspective view, and 5 separated from the structure 102. The covering system 100 includes a substantially cylindrical shaft 104, such as a rod or tube, having a central longitudinal axis 106. The cylindrical shaft 104 is engaged with a motor 108 such that, in use, the motor 108 is operable to rotate the shaft 104 about its longitudinal axis 106. A first guide, in the form of guide rail 110 is attached to the side of roof 10 portion 103 of the structure 102. The function of the guide rail 110 is to enable the motor 108 to move transversely relative to the roof portion 103 in a direction perpendicular to the longitudinal axis 106 of the shaft 104. While the embodiment 100 includes a guide rail 110 fixed to one side of the roof portion 103 of structure 102, it will be appreciated that alternative 15 arrangements are possible for guiding the motor alongside the roof portion 103, within the scope of the invention. For example, in place of guide rail 110 other guiding means, including ropes, chains, cables and so forth may be utilised. Furthemore, the first guide may not be directly attached to the roof portion 103, but may be otherwise disposed upon or adjacent to the roof portion in order to 20 provide the required transverse guidance for the motor 108. The covering system 100 further includes a web of flexible material 114, one edge 116 of which is fixed to the structure 102 proximate to a corresponding first edge of the roof portion 103. It will be appreciated that the material 114 need not be fixed at or near an edge of the roof portion and that, for example, 25 embodiments of the invention are envisaged in which only part of the upper surface of the structure forms an open roof portion and, accordingly, complete coverage of the structure by the web of material may not be required. The edge of the web of material 114 opposed to the fixed edge 116 is fixed to the cylindrical shaft 104. 30 The web of material 114 may be any material suited to the intended purpose of the covering. In particularly preferred embodiments, the material 114 is a PVC tarpaulin having a weight of 650 g/m 2 . This material provides total block-out of sunlight, and is waterproof against rainfall. However, alternative 8 embodiments may employ other materials, such as cloth or shade mesh, in order to provide coverage having differing characteristics. For example, a light cloth or shade mesh may be unsuitable for protection against rainfall, but may provide a level of shade in sunny conditions that substantially reduces the exposure of 5 objects or persons located beneath the structure 102 to heat and ultra-violet radiation from the sun, while still allowing some light to pass through. The covering system 100 accordingly has an open position in which the material 114 is rolled around the cylindrical shaft adjacent to the first edge of the roof portion 103, ie the fixed edge 116 of the material 114. By operation of the 10 motor 108, the web of material 114 is progressively unrolled, and as this happens the motor 108 moves transversely along the roof portion 103 under the guidance of the guide rail 110. In a fully closed position, the web of flexible material 114 is unrolled from the shaft 104 to substantially cover the roof portion 103 of the structure 102, thereby providing shade and/or other protection to objects or 15 persons located beneath the structure 102. Opening of the covering system 100 is achieved by operating the motor in the opposed rotational direction to that employed during closing of the cover. As illustrated in the drawings, closing of the cover is achieved by operating the motor in a counter-clockwise direction when viewed from the orientation shown in the figures, and opening of the cover 20 is achieved by operating the motor in a clockwise direction. The embodiment of the covering system 100 includes a number of further features providing additional advantages and improvements in the operation of the system. These include torsion arm 112, tensioners 118, 120 and projecting stop 122. 25 According to the embodiment 100, the motor 108 is indirectly engaged with the guide rail 110 via the torsion arm 112. The torsion arm 112 performs at least two advantageous functions in the covering system 100. Firstly, the inclusion of the torsion arm prevents the motor housing form rotating under the high levels of torque that may be provided when power is applied. Secondly, the torsion arm 30 112 is engaged with the guide rail 110 so as to allow the motor a degree of vertical movement in normal operation. There are at least two circumstances in which it is desirable to enable the motor 108 to move vertically to a limited degree, these being firstly as the flexible material 114 is rolled or unrolled around 9 the shaft 104, effectively changing the outer diameter of the roll, requiring the central axis 106 of the shaft 104, and hence of the motor 108, to be displaced vertically. It is also advantageous that the shaft 104 be able to pass over the edge of the roof portion 103 opposed to the fixed edge 116 of the material, in 5 order to provide a complete, and potentially waterproof, covering of the structure 102. Clearly, for the shaft 104 to pass over the edge of the roof portion, it is necessary that the shaft 104 and the motor 108 be able to move downwards to a limited degree. The covering system 100 also includes tensioners 118, 120 which are 10 respectively fixed to either end of the shaft 104 and to corresponding points located proximate to either side of the fixed edge 116 of the material 114. The tensioners 118, 120 may be, for example, elastic cords or springs. The purpose of the tensioners to apply a suitable restoring force at both ends of the shaft 104 in the direction of the fixed edge 116 of the material 114. By providing a restoring 15 force that is easily overcome by the operation of the motor during closing of the covering system 100, but large enough to maintain tension during opening and closing of the system, the system may operate more smoothly, and undesired unravelling of the web of material 114 from the shaft 104 may be avoided. As will be appreciated, the provision of an elastic cord or spring in each of 20 the two tensioners 118, 120 is only one way in which the desired restoring force may be applied. For example, in alternative arrangements inelastic materials, such as cord, rope, cable and so forth, may be employed and a pulley system may be used along with counterweights at the end of the tensioners 118, 120 not fixed to the shaft 104, in order to provide a suitable restoring force. 25 The projecting stop 122 provides a particularly simple and advantageous means of ensuring that the closed cover is pulled taut over the roof portion 103 of structure 102. As will be appreciated, it is highly desirable to provide a taut covering when closed, to facilitate runoff of rainwater and to prevent the cover from flapping in the wind. A loose covering would allow rainwater to pool within 30 depressions formed therein, and/or may be caught and lifted or forced downward by gusts of wind. Wind in particular may result in damage to the covering system 100 in the event of sufficiently strong gusts.

10 The covering system 100 employs only a single guide rail 110 for guiding the motor alongside the roof portion 103. While this arrangement is able to operate quite satisfactorally under most conditions, in some circumstances improved strength and/or stability of the structure may be desirable. For 5 example, if the covering system 100 is operated in high wind conditions, the weight of the shaft 104 and covering material 114 may be insufficient to prevent the covering material 114 from blowing away from the structure 102. Accordingly, in Figures 3A and 3B there is depicted an alternative embodiment 300 that utilises a second guide rail 310 to provide greater strength and/or stability in such 10 conditions. In particular, Figure 3A shows a front perspective view of the covering system 300, while Figure 3B illustrates a detail view of the means of engagement 302 between the shaft 104 and the second guide rail 310. More particularly, the alternative covering system 300 includes second guide rail 310 fixed to the side of the roof portion 103 opposed to the side at 15 which rail 110 is fixed, ie at the opposite end of the shaft 104 to the motor 108. A means of engagement 302 is provided between the shaft 104 and the second rail 310 that, in the embodiment 300, is generally similar to the arrangement provided at the opposing end of the shaft 104 except, of course, for the absence of the motor 108. Specifically, a projecting portion 306 extends from the shaft 104, and 20 is connected via bearings 308 to a metal bracket 312. The guide rail 310 provides a lipped channel, within which is disposed a block 304 that is able to slide along the interior of the channel. The block 304 may be made of any suitable material, and in preferred implementations is made of a plastics material which is able to fit reasonably snugly within the guide 310 while sliding smoothly 25 therein. The end of the metal bracket 312 opposed to that at which the shaft 104 is connected is itself rotatably affixed to the plastic block 304, which may be achieved, for example, using a suitably adapted shaft 314 fixed into the block via screw-thread engagement 316. A guiding means similar to the arrangement 302 may be employed at the 30 end of the shaft 104 attached to the motor 108, and in particular a lipped guide rail structure 110 which includes means for transmitting power to the motor 108 is described below with reference to Figure 6. It will be understood that the translational and rotational motion of the metal bracket 312 tracks the 11 corresponding motion of the torsion arm 112, although the metal bracket 312, block 304 and connecting components 306, 308, 314, 316 do not bear or transmit torque, and thus need not have the same level of strength and durability as the corresponding components connected to the motor 108. 5 The operation of the projecting stop 122 in conjunction with the motor 108 and cylindrical shaft 104 is illustrated in the sequence of drawings in Figures 4A, 4B and 4C. As can be seen clearly in these figures, in preferred embodiments the projecting stop 122 is a lock angle. As will be appreciated from the following description of operation, however, other forms of projection may be similarly 10 effective in providing the desired stopping function. For the sake of clarity, the motor 108, guide rails 110, 310 tensioners 118, 120, and other components of the covering systems 100, 300 that are not essential to a general understanding of the operation of the system, have been omitted from Figures 4A, 4B and 4C, to enable the action of the cylindrical shaft 104 to be better appreciated. The 15 general method of operation of the two embodiments 100, 300 is substantially identical, and accordingly the following discussion referring to Figures 4A, 4B and 4C is equally applicable to either embodiment. Figure 4A illustrates the general process of closure of the covering system 100, wherein the cylindrical rod 104 rotates in a counter-clockwise direction, 20 thereby unrolling the web of material 114 over the roof portion 103 of the structure 102. As the cover is closed, the length of material 114 rolled around the shaft 104 is thus progressively reduced. Figure 4B illustrates the covering system 100 in a fully closed, but not taut, configuration. In this configuration, all of the flexible material 114 has been 25 unrolled from the shaft 104, which is now located just beneath the projecting stop 122 located on the vertical surface of the structure 102 below the edge of the roof potion 103. As shown in Figure 4B, the flexible material 114 is draped over the edge of the roof portion 103, but is not yet under any tension. However, the motor may continue to operate in a counter-clockwise direction, resulting in the 30 final configuration shown in Figure 4C. As illustrated in Figure 4C, by continued counter-clockwise operation of the motor the flexible material 114 commences rolling around the shaft 104 in a direction opposed to that in which it is rolled during opening of the covering 12 system 100. In doing so, the cylindrical shaft 104 passes over the lock angle 122 and, as the material 114 starts to roll around the shaft 104, the shaft 104 is drawn back to bear against the underside of the lock angle 122. The rolling action of the shaft 104 against the lower surface of lock angle 122 pulls the shaft 104, towards 5 the main structure 102, opposing the increasing tension thereby created in the material 114. As a result, the web of material 114 is pulled taut over the roof portion 103 of the structure 102, and the complete cover is effectively locked in place beneath the lock angle 122. The cover will not be released from this stable and tight configuration until such time as the motor is operated in the opposing, 10 clockwise, direction in order to open the cover. According to preferred embodiments the motor 108 is a commercially available electric motor, which may be powered from a low voltage (eg 12 volts) DC supply. The motor preferably is capable of providing a relatively high level of torque, and this is particularly advantageous when tightening and locking the 15 closed cover under the lock angle 122 as previously described with references to Figures 4A, 4B and 4C. In preferred embodiments, the motor incorporates and/or is coupled to a gearbox (not shown) in order to provide a desirable torque/speed characteristic. For example, commercially available DC motors suitable for use with embodiments of the invention may be designed to operate at speeds of 20 around 2000 revolutions per minute (rpm). A gearbox is then preferably provided having a gear ratio on the order of 40:1 to provide an operating speed of around 50 rpm. The application of high torque levels requires relatively high power operation which, it will be appreciated, necessitates the supply of relatively high 25 currents at the low operating voltage levels of the motor 108. This power/torque requirement does not present a significant problem, since suitable DC electric motors are commercially available, however it is important to provide an appropriate electric power supply capable of delivering the necessary peak current levels. Again, this poses no significant difficulty since conventional 30 sources of DC electrical power, such as lead-acid batteries, and in particular car batteries, are readily and cheaply available. Operation of a DC motor by a DC source in both clockwise and counter-clockwise directions is also readily achieved, simply by controlling the polarity of the voltage supplied to the motor.

13 Figure 5 illustrates schematically one arrangement for powering the motor 108 according to an embodiment of the invention. According to this arrangement, a power supply 124 is provided which includes a car battery having a nominal 12-volt output and a high-current-supply capacity. The battery of power supply 5 124 is preferably also connected to a mains supply (not shown) for maintaining the charge of the battery. In this respect, the battery may be permanently subject to recharging, or periodically connected to the mains supply for recharging of the battery between operations of the motor 108. A conducting cable 126 is connected to the power supply 124 and fixed to the structure 102 for distributing 10 electric power to the motor 108. To accommodate the motion of the motor 108 along the guide rail 110 during opening and/or closing of the cover a section of "free-hanging" cable 128 is provided. The free-hanging cable 128 is of sufficient length to enable the motor 108 to move between the two ends of guide rail 110. As will be appreciated, however, there are certain disadvantages of 15 providing a section of free-hanging cable 128. In particular, the length of free-hanging cable 128 must generally be at least half the length of the guide rail 110, which in turn is approximately equal to the length of the roof portion to be covered by the covering system. Accordingly, the length of free-hanging cable 128 required in the case of a large structure 102 may result in problems being 20 encountered in use. Specifically, during opening and closing operations the free-hanging cable 128 may become caught on, or entangled with, any objects that may be located beneath the guide rail 110. Any excess length of free-hanging cable 128 may appear untidy or unattractive even when the covering system 100 is fully open or fully closed. 25 In order to mitigate the aforementioned problems occurring with a free-hanging cable 128, in alternative embodiments the present invention also accommodates alternative power transmission arrangements, one of which will now be described with reference to Figure 6. Specifically, Figure 6 illustrates a cross-sectional view of the guide rail 110, upon which is disposed insulating 30 material 130, 131, and conductive strips 132, 133. The conductive strips 132, 133 may be connected to the conductors of cable 126, which are in turn connected to the terminals of the power supply 124. The conductive strips 132, 133 therefore act as busbars for distributing power from the power supply 124 14 along the length of the guide rail 110. Insulating material 130, 131 insulates the power to busbars 132, 133 from the guide rail 110, which would itself be fabricated from a metal. The busbars 132, 133 may conveniently be readily-available copper or 5 aluminium strips, and insulation and adhesion may be provided by using double-sided aircraft quality plastic tape insulation as the insulating material 130, 131. The power conduced along the busbars 132, 133 may be provided to the motor 108 by fitting suitable conductive brushes, such as carbon brushes, to the 10 torsion arm 112 with fixed conductive wires being provided between the brushes and the supply terminals of the motor 108. This arrangement avoids the need for free-hanging conductors 128. It will be understood that the foregoing description of preferred embodiments of the invention is exemplary only, and that the invention is not to 15 be limited to the specific arrangements described herein. Rather, the scope of the invention is defined by the claims appended hereto.

Claims (12)

1. A covering system providing a retractable covering for a structure having a roof portion that is normally open to the environment, the system including: an at least substantially cylindrical shaft having a central longitudinal axis; 5 a motor with which the cylindrical shaft is engaged such that, in use, the motor is operable to rotate the shaft about said longitudinal axis; a first guide disposed upon or adjacent to the roof portion of the structure with which the motor is operably engaged via a torsion arm, whereby the motor is able to move transversely relative to the roof portion along the first guide in a 10 direction perpendicular to the longitudinal axis of the shaft wherein the first guide is a rigid track or rail with which the motor is operably engaged so as to be slidable alongside the roof portion of the structure; and a web of flexible material, a first edge of which is fixed to the structure and an opposing edge of which is fixed to the cylindrical shaft, 15 the covering system having an open position wherein the web of flexible material is substantially rolled around the cylindrical shaft adjacent to a location on the structure at which said first edge of the web is fixed and a closed position wherein the web of flexible material is unrolled from the shaft to substantially cover the roof portion of the structure, and being operable between said open and 20 closed positions by operation of the motor in corresponding opposed rotational directions.

2. The covering system of claim 1 wherein one end of the torsion arm is directly engaged with the first guide, and the motor is fixed to an opposing end of the torsion arm. 25

3. The covering system of either claim 1 to 2 including at least one tensioner provided at an end of the cylindrical shaft, the tensioner applying a restoring force in the direction of the fixed first edge of the web of flexible material. 16

4. The covering system of any one of claims 1 to 3 further including a projecting stop disposed at an edge of the roof portion of the structure that is opposed to the fixed first edge of the web of flexible material, and arranged such that during closure of the covering system the cylindrical shaft passes over the 5 stop and is subsequently drawn back to bear against the stop by continuing rotation of the shaft which causes the web to fully unroll from the shaft and to commence rolling around the shaft in an opposing direction.

5. The covering system of claim 4 wherein the projecting stop is a lock angle.

6. The covering system of claim 5 wherein the projecting stop is located 10 along a substantially vertical surface of the structure and below the upper surface of the roof portion, and projects in a substantially horizontal direction such that, when closed, the roof portion is fully covered, and the cylindrical shaft is securely located beneath the covered roof level and bears against a lower surface of the stop. 15

7. The covering system of any one of claims 1 to 6 wherein the motor is an electric motor to which power is provided via a free-hanging cable of sufficient length to reach the motor in both the open and closed positions.

8. The covering system of any one of claims 1 to 7 wherein the motor is an electric motor to which power is provided via conductive tracks or busbars 20 disposed within the first guide, and wherein brush contacts are provided to conduct power from the busbars to the motor when the motor is located at any position along the first guide.

9. The covering system of any one of claims 1 to 8 wherein the motor is engaged with the cylindrical shaft at one end thereof, and a second guide is 25 disposed upon or adjacent to the roof portion of the structure and is engaged with an opposing end of the cylindrical shaft, such that the system has improved strength and/or stability in use. 17

10. The covering system of any one of the preceding claims wherein the torsion arm is a discrete component fastened at one end to an engaging member within the first guide, and at an opposing end to a casing of the motor.

11. The covering system of claim 10 wherein the fastening of the ends of the 5 torsion arm is adapted to permit a degree of vertical displacement of the motor.

12. A covering system substantially as herein described with reference to any one or more of the accompanying drawings. ON SITE STEELFAB PTY LTD WATERMARK PATENT & TRADE MARK ATTORNEYS P2621 OAUOO