AU2004254282B2

AU2004254282B2 - Carrier and drive arrangement for a solar energy reflector system

Info

Publication number: AU2004254282B2
Application number: AU2004254282A
Authority: AU
Inventors: Peter Le Lievre
Original assignee: Areva Solar Pty Ltd
Current assignee: Areva Solar Pty Ltd
Priority date: 2003-07-01
Filing date: 2004-07-01
Publication date: 2009-10-01
Anticipated expiration: 2024-07-01
Also published as: AU2004254282A1

Description

CARRIER AND DRIVE ARRANGEMENT FOR A SOLAR ENERGY REFLECTOR SYSTEM FIELD OF THE INVENTION 5 This invention relates to a carrier and drive arrangement for a solar energy reflector system of a type that is employed for reflecting incident radiation to a solar energy collector system. 10 BACKGROUND OF THE INVENTION Various solar energy reflector-collector systems have been developed for use in harnessing solar radiation that 15 falls incident over areas that might range in size from 5x10n2 to 25x10'm2. In this context reference is made to collector systems that have been disclosed in Australian Patents 694335 and 724486 dated 28 March 1996 and 19 December 1997 respectively. 20 The most relevant of the earlier known reflector collector systems, including those disclosed in the referenced patents, employ a field of reflectors which are driven to track movement of the sun (relative to the 25 earth) and which are orientated to reflect incident radiation to distant, elevated collector systems. In the case of the system that is disclosed in Patent number 694335, at least some of the reflectors are mounted and arranged to be driven in a manner such that their 30 orientation may be changed to move the direction of reflected radiation from one collector system to another. The present invention has been developed from a perceived need for a carrier that is suitable for 35 supporting a reflector element in a reflector system and which also provides for convenient transmission of sun tracking drive from an electric drive motor. 16198681 (GHMatters) 3/09/09 2 SUMMARY OF THE INVENTION The present invention provides in a first aspect a carrier and drive arrangement for use in a solar energy 5 reflector system and which comprises: a) a carrier structure having i) a platform for supporting a reflector element, ii) a frame portion that includes hoop-like end 10 members between which the platform extends and iii) support members which support the frame portion by way of the end members and which accommodate turning of the carrier structure about an axis of rotation that is substantially coincident 15 with a longitudinal axis of the reflector element when supported by the platform; and b) a drive system incorporating an electric motor for imparting turning drive to the carrier structure by way of at least one of the end members. 20 The present invention provides in a second aspect a carrier and drive arrangement for use in a solar energy reflector system and which comprises: 25 a) a carrier structure having i) a reflector element, ii) a platform for supporting the reflector element, iii) a frame portion that includes hoop-like end 30 members between which the platform extends, wherein the frame portion comprises a space frame, and wherein each of the hoop-like end members has a channel-section circumferential portion, and 35 iv) support members which support the frame portion by way of the end members and which accommodate turning of the carrier structure about an axis 16198681 (GHMatters) 3109109 2a of rotation that is substantially coincident with a longitudinal axis of the reflector element when supported by the platform, wherein the support members comprise spaced-apart 5 supporting rollers which track within the circumferential portion of associated ones of the end members; and b) a drive system incorporating an electric motor for 10 imparting turning drive to the carrier structure. OPTIONAL FEATURES OF THE INVENTION The carrier structure may, in one embodiment of the 15 invention, be carried by the support members in a manner which accommodates unidirectional rotation of the carrier structure about the axis of rotation that is substantially coincident with the longitudinal axis of the reflector element. By "substantially coincident" is meant that the 20 axis of rotation is located coincident with or adjacent to the longitudinal axis of the reflector element. The drive system incorporating the electric motor may, in accordance with one embodiment of the invention, be arranged to impart unidirectional turning drive to the 25 carrier structure. By providing such unidirectional drive, the traditional requirement for a reversible motor or a pivoting mechanism, with attendant backlash and other problems, is avoided. Also, by employing such a drive system, the carrier structure may be parked in a selected 30 angular position with the reflector element orientated downwardly, to shield it from adverse ambient conditions, during the process of turning (i.e., rotating) the carrier structure through 360 degrees during each 24-hour period. Furthermore, the carrier structure may at any time within 35 each 24-hour period be rotated temporarily to a selected angular position with the reflector element orientated in 1619868_1 (GHMatters) 3/09/09 2b a direction away from potentially damaging climatic conditions. Also, the drive system may, in one embodiment of the invention, be arranged to impart the unidirectional drive 5 to the carrier structure by 1619868_1 (GHMatters) 3/09109 WO 2005/003646 PCT/AU2004/000883 -3 way of one only of the end members of the frame portion of the carrier structure. The platform for the reflector element may, in one embodiment of the 5 invention, comprise a fluted or corrugated metal panel, with the flutes or corrugations forming the stiffening elements of the platform. In such case, the reflector element will be supported upon the crests of the flutes or corrugations. Furthermore, although the flutes or corrugations may extend in a direction that intersects the longitudinal axis of the 10 reflector element, the flutes or corrugations desirably are orientated to extend in a direction parallel to the longitudinal axis of the reflector element. Also, although the platform may be formed with a flat surface or such 15 that the crests of the flutes or corrugations are located in a flat plane, the platform desirably is curved concavely in a direction orthogonal to the longitudinal axis of the reflector element. The frame structure of the carrier structure may comprise a skeletal 20 frame structure having the hoop-like end members that extend about the axis of rotation of the carrier structure and between which the platform extends. The support members which support the carrier structure by way of the 25 hoop-like end members, may comprise spaced-apart supporting rollers. Such rollers desirably are sized and otherwise arranged to track within a channel region of the associated end members. The drive system for imparting drive to the carrier structure may, in 30 accordance with one embodiment of the invention, be coupled to at least one of the hoop-like end members and it desirably incorporates a link chain that extends around and is fixed to one of the end members to form, in effect, a gear wheel. In the latter case a sprocket will be provided to engage with the link chain and to impart drive to the end 35 member from the electric motor. With such a drive arrangement, a relatively inexpensive electric motor may be employed and, with appropriately sized end members of the carrier structure, a high WO 2005/003646 PCT/AU2004/000883 -4 reduction in drive velocity and a commensurate increase in torque transmission may be obtained. The reflector element may comprise a single panel-shaped glass mirror 5 or a reflective metal panel, but it desirably comprises a plurality of square or rectangular glass mirrors that are mounted in edge abutting relationship upon the supporting platform. In this case the rear, silvered faces of the mirrors may be protected against adverse ambient conditions by sealing surrounding gaps and spaces with a silicone or 10 other suitable sealant. When, as mentioned above, the platform for the reflector element is curved concavely, the reflector element will be secured to the platform in a manner such that the concavity will be transferred to the reflecting surface of the reflector element. 15 The carrier structure and drive system of the invention may be embodied in various arrangements, one of which is now described, by way of example, with reference to the accompanying drawings. The carrier structure and drive system is described in the context of a complete reflector system. 20 BRIEF DESCRIPTION OF THE DRAWINGS In the drawings Figure 1 shows a perspective view of the reflector system with a carrier structure of the system rotated to an angular position in which a 25 reflector element is orientated to reflect in an upward direction, Figure 2 shows a perspective view of the same reflector system but with the carrier structure rotated through approximately 180 degrees to expose the underside of a platform and skeletal frame structure for the reflector element, 30 Figure 3 shows, on an enlarged scale, a portion of an end member and a drive system of the reflector system, and Figure 4 shows, also on an enlarged scale, a portion of the end member and an associated mounting arrangement for the reflector system. 35 DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION As illustrated, the reflector system in its exemplified embodiment comprises a carrier structure 10 to which a reflector element 11 is WO 2005/003646 PCT/AU2004/000883 -5 mounted. The carrier structure itself comprises an elongated panel-like platform 12 which is supported by a skeletal frame structure 13. The frame structure includes two hoop-like end members 14. 5 The members 14 are centred on and extend about an axis of rotation that is approximately coincident with a central, longitudinally-extending axis of the reflector element 11. The axis of rotation does not need to be exactly coincident with the longitudinal axis of the reflector element but the two axes desirably are at least adjacent on another. 10 In terms of overall dimensions of the reflector system, the platform 12 is approximately twelve metres long and the end members 14 are approximately two metres in diameter. 15 The platform 12 comprises a corrugated metal panel and the reflector element 11 is supported upon the crests of the corrugations. The corrugations extend parallel to the direction of the longitudinal axis of the reflector element 11, and the platform 12 is carried by six transverse frame members 15 of the skeletal frame structure 13. End 20 ones of the transverse frame members 15 effectively comprise diametral members of the hoop-like end members 14. The transverse frame members 15 comprise rectangular hollow section steel members and each of them is formed with a curve so that, when 25 the platform 12 is secured to the frame members 15, the platform is caused to curve concavely (as viewed from above in Figure 1) in a direction orthogonal to the longitudinal axis of the reflector element 11. The same curvature is imparted to the reflector element 11 when it is secured to the platform 12. 30 The radius of curvature of the transverse frame members 15 is in the range of twenty to fifty metres and preferably of the order of thirty-eight metres. 35 The skeletal frame 13 of the carrier structure 10 also comprises a rectangular hollow section steel spine member 16 which interconnects the end members 14, and a space frame which is fabricated from WO 2005/003646 PCT/AU2004/000883 -6 tubular steel struts 17 connects opposite end regions of each of the transverse frame members 15 to the spine member 16. This skeletal frame arrangement, together with the corrugated structure of the platform 12 provides the composite carrier structure 11 with a high 5 degree of torsional stiffness. The hoop-like end members 14 are formed from channel section steel, such that each end member is provided with a U-shaped circumferential portion and, as shown in Figure 4, each of the members 10 14 is supported for rotation on a mounting arrangement that comprises two spaced-apart rollers 18. The rollers 18 are positioned to track within the channel section of the respective end members 14, and the rollers 18 provide for turning (ie, rotation) of the carrier structure 10 about the axis of rotation that is approximately coincident with the 15 longitudinal axis of the reflector element 11. As also shown in Figure 4, a hold-down roller 18a is located adjacent the support rollers 18 and is positioned within the associated end member 14 to prevent lifting of the reflector system under adverse 20 weather conditions. A drive system, as shown in see Figure 3, is provided for imparting unidirectional drive to the carrier structure 10 and, hence, to the reflector element 11. The drive system comprises a shaded pole or other 25 similar such non-reversible electric motor 19 having an output shaft coupled to a sprocket 20 by way of reduction gearing 21. The sprocket 20 meshes with a link chain 22 through which drive is directed to the carrier structure 10. 30 The link chain 22 extends around and is fixed to the periphery of the outer wall 23 of the channel-section of one of the end members 14. That is, the link chain 22 affixed to the end member effectively forms a type of gear wheel with which the sprocket 20 engages. 35 With the end member 14 having a diameter in the order of 2.00 m and the sprocket 20 having a pitch circle diameter of 0.05 m, reduction gearing and torque amplification in the order of (40.r): 1 may be WO 2005/003646 PCT/AU2004/000883 -7 obtained, where r is the reduction obtained through gearing at the output of the electric motor 19. The reflector element 11 is formed by butting together five glass 5 mirrors, each of which has the dimensions 1.8 m X 2.4 m. A silicone sealant is employed to seal gaps around and between the mirrors and to minimise the possibility for atmospheric damage to the rear silvered faces of the mirrors, and the mirrors are secured to the crests of the platform 12 by a urethane adhesive. 10 The mirrors have a thickness of 0.003 m and, thus, they may readily be curved in situ to match the curvature of the supporting platform 12. Depending upon requirements, two or more of the above described 15 reflector systems may be positioned linearly in a row and be connected one to another by way of adjacent ones of the hoop-like end members 14. In such an arrangement a single drive system may be employed for imparting unidirectional drive to the complete row of reflector systems. 20 Variations and modifications may be made in respect of the carrier structure as above described by way of example without departing from the scope of the appended claims.

Claims

1. A carrier and drive arrangement for use in a solar energy reflector system and which comprises: 5 a) a carrier structure having i) a reflector element, ii) a platform for supporting the reflector element, 10 v) a frame portion that includes hoop-like end member between which the platform extends, wherein the frame portion comprises a space frame, and wherein each of the hoop-like end members has a channel-section circumferential 15 portion, and vi) support members which support the frame portion by way of the end members and which accommodate turning of the carrier structure about an axis of rotation that is substantially coincident 20 with a longitudinal axis of the reflector element when supported by the platform, wherein the support members comprise spaced-apart supporting rollers which track within the circumferential portion of associated ones of 25 the end members; and b) a drive system incorporating an electric motor for imparting turning drive to the carrier structure. 30

2. The carrier and drive arrangement as claimed in claim 1 wherein the drive system is arranged to impart unidirectional turning drive to the carrier structure by way of one of the end members. 35

3. The carrier and drive arrangement as claimed in claim 1 wherein the drive system comprises: 16198681 (GHMatters) 3/09109 9 a) a link chain that extends around and is fixed to the end member to form, in effect, a gear wheel, and b) a sprocket for transferring drive from the electric 5 motor to the link chain.

4. The carrier and drive arrangement as claimed in claim 1 wherein the platform comprises a panel-like platform which is formed with stiffening elements in the form of io corrugations and wherein the reflector element is supported upon the crests of the corrugations.

5. The carrier and drive arrangement as claimed in claim 1 wherein the platform comprises a panel-like platform is which is formed with stiffening elements in the form of flutes and wherein the reflector element is supported upon the crests of the flutes.

6. The carrier and drive arrangement as claimed in claim 20 4 wherein the stiffening elements are orientated to extend in a direction parallel to the longitudinal axis of the reflector element.

7. The carrier and drive arrangement as claimed in claim 25 5 wherein the stiffening elements are oriented to extend in a direction parallel to the longitudinal axis of the reflector element.

8. The carrier and drive arrangement as claimed in claim 30 1 wherein the platform is curved concavely in a direction orthogonal to the longitudinal axis of the reflector element.

9. The carrier and drive arrangement as claimed in claim 35 8 wherein the platform is curved with a radius of curvature within the range of 20-50 meters. 16198681 (GHMatters) 3/09/09 10

10. The carrier and drive arrangement as claimed in claim 8 wherein the reflector element is secured to the platform in a manner such that the curvature of the platform is imparted to the reflector element. 5

11. The carrier and drive arrangement as claimed in claim 1 wherein the reflector element comprises a panel-shaped glass mirror. 10

12. The carrier and drive arrangement as claimed in claim 1 wherein the reflector element comprises a plurality of edge-abutting glass mirrors.

13. The carrier and drive arrangement as claimed in claim 15 11 wherein the reflector element is adhered to the platform.

14. The carrier and drive arrangement as claimed in claim 1 wherein each of the hoop-like end members has a 20 diametrically extending member that is constituted by a transverse frame member.

15. The carrier and drive arrangement as claimed in claim 14, wherein the transverse frame members are curved. 25

16. The carrier and drive arrangement as claimed in claim 15, wherein the platform is secured to the transverse frame members in a manner such that the curvature of the transverse frame members are imparted to the platform, and 30 wherein the reflector element is secured to the platform in a manner such that the curvature of the platform is imparted to the reflector element.

17. The carrier and drive arrangement as claimed in claim 35 14, wherein the space frame comprises struts connecting opposite end regions of each of the transverse frame members to a spine member. 16198681 (GHMatters) 3/09/09 11

18. The carrier and drive arrangement as claimed in claim 17, wherein the spine member interconnects the end members. 5

19. The carrier and drive arrangement as claimed in claim 1, wherein the support members further comprise a hold down roller which prevents the lifting of the end members. 10

20. The carrier and drive arrangement as claimed in claim 1, wherein the end members extend about the axis of rotation of the carrier structure, and wherein the platform extends in a longitudinal direction between the end members. 15

21. The carrier and drive arrangement as claimed in claim 1, wherein two or more carrier structures are positioned linearly in a row and are connected to one another by way of adjacent ones of the end members. 20

22. The carrier and drive management of claim 21, wherein the drive system drives the row or two or more carrier structures by way of at least one of the end members. 25

23. A carrier substantially as herein described with reference to the drawings. 1619868_1 (GHMatters) 3109/09