Holding device

Abstract

A device for holding a material and a method for holding such materials. The device includes a lower part having at least two engagement points, at least one elongated flexible tensioning element that is attached suspended between the engagement points, and traction mechanisms that are attached on the tensioning element or are part of the tensioning element. The tensioning element is connected to, encloses or carries the material, and the device is configured such that all traction mechanisms can be pulled simultaneously with identical or different tensile force in the direction of the lower part.

Claims

1. A device for holding a parabolic reflector or a parabolic trough collector, comprising: a lower part having at least two engagement points provided at distal ends thereof; at least one elongated, flexible tensioning element attached for suspension at the engagement points to carry the parabolic reflector or the parabolic trough collector; at least one joist spaced from and moveable relative to the at least one elongated, flexible tensioning element; and traction means attached to the at least one elongated, flexible tensioning element or are part of the at least one elongated, flexible tensioning element, the traction means being configured to simultaneously receive a tensile force, by action of downward movement of the at least one joist, in a direction towards the lower part in such a manner that the at least one elongated, flexible tensioning element, and thus, the parabolic reflector or the parabolic trough collector, is to thereby adopt and maintain a parabolic shape.

2. A device for forming and holding a parabolic reflector or a parabolic trough collector, comprising: a lower part having at least two engagement points provided at distal ends thereof; at least one elongated, flexible tensioning element attached for suspension at the engagement points to connectedly carry a reflective material to form the parabolic reflector or the parabolic trough collector; at least one joist spaced from and downwardly moveable relative to the at least one elongated, flexible tensioning element; and traction means attached to the at least one elongated, flexible tensioning element or are part of the at least one elongated, flexible tensioning element, the traction means being configured to simultaneously receive a tensile force, by action of downward movement of the at least one joist, in a direction towards the lower part in such a manner that the at least one elongated, flexible tensioning element, and thus, the connected reflective material forming the parabolic reflector or the parabolic trough collector, is to thereby adopt and maintain a parabolic shape.

3. The device of claim 1, wherein the tensile forces on the traction means are different from each other.

4. The device of claim 1, wherein the lower part comprises at least two support arms having ends which form the engagement points.

5. The device of claim 1, wherein the lower part comprises pylons arranged having ends which form or comprise the engagement points.

6. The device of claim 1, wherein the at least one elongated, flexible tensioning element comprises a cable, a wire, a rope, or a chain, or a flexible sheet metal.

7. The device of claim 1, wherein the traction means and/or the at least one elongated, flexible tensioning element are adjustable with respect to their respective lengths.

8. The device of claim 1, wherein the traction means comprises a plurality of spaced apart rods, ropes, chains, cables, or elastic springs.

9. The device of claim 1, wherein the traction means is arranged to extend substantially vertically such that the tensile forces are acting thereon substantially vertically towards the lower device part.

10. The device of claim 1, wherein the traction means comprises rods, ropes, chains, cables, or elastic springs that are spaced apart such that the distance between neighboring ones thereof are substantially identical, and the tensile force acting on each is substantially identical.

11. The device of claim 1, wherein the at least one joist is guided with respect to the lower part in such a manner that during a movement of the at least one joist in the direction of the lower part, the tensile force is exerted on the traction means.

12. The device of claim 1, wherein the at least one joist comprises a plurality of joists which are connected via a connecting element, and which are configured to be set in motion jointly.

13. The device of claim 12, wherein: the traction means comprises sections of an elongated bendable traction rope; deflection rollers are to moveably mount each traction rope and are provided on the at least one elongated, flexible tensioning element and the joists; and the traction rope is guided by the deflection rollers on the at least one elongated, flexible tensioning element and the joists.

14. The device of claim 1, wherein horizontal projections arranged between spaces of neighboring deflection rollers along the at least one elongated, flexible tensioning element are substantially identical.

15. The device of claim 1, further comprising a tracking system for tracking movement of the sun.

16. The device of claim 1, wherein the distance of the engagement points from one another and/or the length of the traction means between the engagement points is adjustable.

17. The device of claim 1, wherein the at least one elongated, flexible tensioning element comprises a circumferentially extending rope.

18. A device for forming and holding a parabolic reflector or a parabolic trough collector, comprising: a lower part having at least two support arms having ends which form engagement points; at least one elongated, flexible tensioning element attached for suspension at the engagement points to connectedly carry a reflective material to form the parabolic reflector or the parabolic trough collector; at least one joist rigidly attached to the lower part and spaced from the at least one elongated, flexible tensioning element; and traction means extending spaced apart between and attached to the at least one elongated, flexible tensioning element and the at least one joist, the traction means being configured to simultaneously receive a tensile force, by adjustment of the respective lengths of the traction means, in a direction towards the lower part in a manner such that the at least one elongated, flexible tensioning element, and thus, the connected reflective material forming the parabolic reflector or the parabolic trough collector, is to thereby adopt and maintain a parabolic shape.

19. A method for forming and holding a parabolic reflector or a parabolic trough collector, the method comprising: attaching an elongated, flexible tensioning element which is to connectedly carry a reflective material to form the parabolic reflector or the parabolic trough collector, between at least two engagement points of a lower part; attaching at least one joist rigidly to the at least one elongated, flexible tensioning element; and simultaneously applying a tensile force to a traction means, either by action of downward movement of the at least one joist or by adjustment of length of the traction means, in a direction towards the lower part in a manner such that the at least one elongated, flexible tensioning element, and thus, the connected reflective material forming the parabolic reflector or the parabolic trough collector, is to thereby adopt and maintain a parabolic shape.

20. The method of claim 19, further comprising: setting an aperture of the parabolic reflector or the parabolic trough collector by displacing the engagement points symmetrically with respect to the lower part in a horizontal direction; and setting a focal length of the parabolic reflector or the parabolic trough collector by adjusting the length of the elongated, flexible tensioning element between the engagement points.

Description

DRAWINGS

(1) The invention is now explained in greater detail by means of exemplary embodiments in the following drawings.

(2) FIG. 1 shows a schematic illustration that explains the operating principle;

(3) FIGS. 2a-2g shows different embodiments of the device in accordance with the invention.

(4) FIG. 3 shows an axonometric illustration of a parabolic trough collector with adjustable parameters.

(5) FIG. 4 shows a side view of the parabolic trough collector illustrated in FIG. 3.

(6) FIG. 5 shows an axonometric illustration of a connection, illustrated in FIGS. 3 and 4, between a traction means and a joist.

(7) FIG. 6 shows an axonometric illustration of a pylon of the parabolic trough collector illustrated in FIG. 3 and FIG. 4.

DESCRIPTION

(8) For reasons of simplification, a required absorber tube or a photovoltaic module is not illustrated in any of the schematic drawings.

(9) FIG. 1 shows a portion of the tensioning element 21 in the clamped state with the forces acting thereon.

(10) FIG. 2a shows a first embodiment of the invention. A lower part 7 has support arms 32 which are arranged at an obtuse angle with respect to one another and the cross-section of which decreases from the lower part 7 towards their ends. Engagement points 31 are provided on the tips of the support arms. The engagement points can be fastening points or rollers. A rope 21 is spanned between the engagement points.

(11) The rope 21 carries a reflector 25, for example in the form of mirror segments that are movably connected to one another or are not connected. Traction means 19 are attached on the rope 21 and are fastened at their other ends to a joist 14. The traction means 19 are attached at identical horizontal distances from one another. When the joist 14 is pulled downwards, as indicated by the arrows, identical forces are exerted on each of the traction means, and the tensioning element adopts a parabolic shape.

(12) FIG. 2b shows a second exemplary embodiment of the device in accordance with the invention. In this case, the engagement points 31 are not used for fixation, but for deflecting the rope 21. The rope 21 is configured as a circumferentially extending rope and runs around the support arms.

(13) FIG. 2c shows another exemplary embodiment of the invention. In this case, the traction means are formed by sections of an elongated bendable traction rope, wherein deflection rollers 33 for movably mounting the traction rope are provided at the rope 21 and on the joist 14, and the traction rope is guided alternately through the deflection points on the tensioning element and on the joist.

(14) FIG. 2d shows another exemplary embodiment of the invention. The exemplary embodiment corresponds to that of FIG. 2b; however, in this case, the reflector 25 is connected at its end to the rope 21. The traction means 19 engage directly on the reflector 25 and not on the rope 21.

(15) FIG. 2e shows another exemplary embodiment of the invention. The exemplary embodiment corresponds to that of FIG. 2b; however, in this case, there are no separate traction means, but the rope 21 is clamped together at predetermined positions by clamps 34, welds or the like and is directly connected to the joist 14 at the part clamped in this manner. As a result, the rope itself acts as a traction means and no separate traction means are necessary. By the movement of the joist 14, a tensile force in the meaning of the invention is exerted on the clamped parts of the rope 21 without the need of separate traction means.

(16) FIG. 2f shows another exemplary embodiment of the invention. The exemplary embodiment corresponds to that of FIG. 2b; however, in this case, the joist 14 is rigidly fastened to the lower part 7. The rope 21 is circumferentially attached and carries the reflector 25. For exerting a tensioning force on the rope 21 (indicated by the arrows) tensioning devices (not illustrated), for example turnbuckles, are arranged on the rope 21. As a result, a shape of the rope 21 predetermined by the traction means 19 can be achieved in a simple manner without the need that the supporting structure itself has to be adjustable.

(17) FIG. 2g shows another exemplary embodiment of the invention. A lower part 7 having four support arms 32 arranged perpendicular to one another is provided. The support arms 32 carry two ropes 21 that are tensioned via two joists 14 that are aligned to be perpendicular to one another. As a result, a substantially parabolic shape is obtained for the spanned reflector 25. The parabolic shape can be further improved by using additional support arms or joists.

(18) FIGS. 3 through 6 show another exemplary embodiment of the invention that is illustrated in detail. FIG. 4 shows a side view of the parabolic trough collector illustrated in FIG. 3. FIG. 5 shows an axonometric illustration of a connection, illustrated in FIG. 3 and FIG. 4, between a traction means and a joist. FIG. 6 shows an axonometric illustration of a pylon of the parabolic trough collector illustrated in FIG. 3 and FIG. 4.

(19) The ropes 21 are fitted in curved saddles 1 between pylons 2 and form parabolas which have centrally extending symmetry axes 27.

(20) The parabolic shape of the ropes is effected by applying a force that acts parallel to the symmetry axes of the parabolas 27 and is uniformly distributed along the direction perpendicular to the symmetry axes 27.

(21) This force is exerted by traction means 19 which connect the ropes 21 to the joists 14. The traction means are aligned parallel to the symmetry axes of the parabolas 27 and the distances between them are identical. All joists 14 are connected to a longitudinal strut 15 that extends perpendicular to the symmetry axes of the parabolas 27.

(22) The longitudinal strut 15 is pulled to a fixed lower part 7 by a threaded rod 8, which is welded to the floating longitudinal strut 15 in the middle thereof, and a clamping nut 9 with a force that is higher than the weight force of the ropes 21 and the reflective material and all other acting forces such as, e.g., the wind loads. Thus, the weights of the ropes 21 and the reflective material 25 and all other acting forces are negligibly low.

(23) The connection between the traction means 19 and the ropes 21 is established by wire rope clamps 20.

(24) The traction means 19 are threaded in the vertical holes 26 of the joists 14 in a symmetrical manner about the symmetry axes of the parabolas 27 so that the distances between the traction means are identical.

(25) Wire rope clamps 23, which are more clearly shown in FIG. 4, are clamped onto the lower parts 24 of the traction means 19, which lower parts are located below the joists 14. The distances between each rope 21 and the wire rope clamps 23 clamped onto the traction means form a parabola. Thus, the exerted tensile forces are almost equal in all individual traction means 19, and the ropes 21 are brought into a parabolic shape.

(26) For clarity reason, not all freely suspended parts of the traction means, which are located below the joists 14, and the wire rope clamps 23 clamped thereon are shown in FIG. 3 and FIG. 4 (they are shown only for seven traction means 19). In FIG. 3, six pylons 2, two pylons 2 for each rope 21, are illustrated. On their tips, these pylons 2 have curved saddles 1 in which the ropes 21 are fitted. These saddles 1 have the task to convert almost all forces (including the wind loads) acting on the parabolic trough collector into compressive forces acting onto the pylons 2; thus, material costs for the pylons 2 and the static substructure can be saved.

(27) Each pylon 2 has a continuous opening 3 that has two functions. Firstly, to permit the movement of the floating longitudinal strut 15 with the joists 14, which movement is parallel to the symmetry axes of the parabolas 27, when unscrewing or tightening the clamping nut 9. Secondly, when adjusting the aperture 28 of the parabolic trough collector, the pylons 2 are displaced perpendicular to the symmetry axes of the parabolas 27, which is made possible by the continuous opening 3 in any height of the joists 14.

(28) In accordance with a first exemplary embodiment of the method in accordance with the invention, the aperture 28 and the focal length 29 of the parabolic trough collector are adjustable, wherein it has to be taken into account that prior to adjusting the aperture 28 or the focal length 29:

(29) a. the parabolic trough collector is brought into the horizontal position so that the pylons 2 are vertical,

(30) b. then, the detachable connections between the ropes 21 and the narrow (flat) mirror segments or the bendable reflective material 25 are disconnected,

(31) c. then, the mirror segments or the bendable reflective material 25 are/is removed,

(32) d. then, the clamping nut 9 is unscrewed in order to relieve the tensile forces of the traction means 19 and the ropes 21,

(33) e. then, the wire rope clamps 20, which connect the traction means 19 to the ropes 21, are disassembled,

(34) f. then, the wire rope clamps 23, which are clamped onto the parts of the tractions means 24 located below the joists 14, are disassembled, and

(35) g. then, the traction means 19 are removed.

(36) The aperture 28 can be adjusted as desired by:

(37) a. unscrewing the nuts 22, which are screwed tightly on the thread ends of the long rods 12, and pulling out the rods 12,

(38) b. subsequently displacing the pylons 2 on the lower part 7 horizontally and symmetrically about the symmetry axes of the parabolas 27. In order to enable this displacement in any desired height of the joists, each pylon 2 has a continuous opening 3. All pylons 2 on one of the two sides of the ropes 21 have to be displaced by the same distance and in the same direction. All pylons 2 on one of the two the sides of the ropes 21 have to be displaced by the same distance and in the same direction,

(39) c. subsequently, when the required aperture 28 is achieved, inserting long rods 12 into the holes 13 in the lower part 7 and into the two holes 30 in the tongues 11 of the pylons 2, which are shown in FIG. 4. Thus, the pylons 2 have no clearance because their tongues 11 fit perfectly in grooves 18 in the lower part 7, and

(40) d. subsequently fastening the rods 12 by tightly screwing the nuts 22 onto the thread ends of said rods.

(41) The focal length 29 can be adjusted as desired by:

(42) a. pulling in the ropes 21 by means of the rollers 10, which are located on both sides of the ropes 21 and which are similar to fishing reels with respect to structure and function, if the focal length 29 is to be increased, or by elongating them if the focal length 29 is to be reduced. It has to be ensured that all lengths of the ropes 21 are equal after the adjustment, and

(43) b. subsequently, upon reaching the length that results in the desired focal length 29, fitting the ropes 21 in the saddles 1 and setting these length by the rollers 10 that are fastened on the lower part 7.

(44) After the adjustment of the aperture 28 or the focal length 29, the ropes 21 are brought again into a parabolic shape, and the reflective material 25 is secured on the ropes 21 by:

(45) a. threading the traction means 19 into the vertical holes 26 of the joists 14 and symmetrically about the symmetry axes of the parabolas 27 so that the distances between the traction means are equal,

(46) b. subsequently connecting the upper ends of the traction means 19 to ropes 21 by means of wire rope clamps 20 so that all traction means 19 are vertical. These connections have to be strong enough in order to prevent the traction means 19 from sliding off the ropes 21,

(47) c. subsequently clamping wire rope clamps 23 onto those portions of the traction means 24 that are below the joists 14 so that the distances between each rope 21 and the wire rope clamps 23 clamped onto the traction means 19 form a parabola,

(48) d. measuring the distances where the two traction means 19 are connected on the far left and the far right to the rope 21 and the distance in the middle of the rope 21 between the rope 21 and the joists 14 in order to obtain the equation of the parabola,

(49) e. subsequently tightening the clamping nut 9 with a force that is greater than the weight of the rope 21 and the reflective material 25. Thus, the exerted tensile forces are almost equal in all individual traction means 19, and the ropes 21 are brought into a parabolic shape,

(50) f. subsequently fastening mirror elements or bendable reflective material 25 on the ropes 21 using detachable connections, and

(51) g. subsequently adjusting the height of the absorber tube or the photovoltaic module by means of the adjustable absorber holder 17 which consists of two profiled elements, one of which slides into the other one and has a hole 16 with an internal thread, in order to set the desired height by tightening a screw.

(52) The length of the parabolic trough collector is controlled by arranging the required number of ropes 21 along the longitudinal axis 5. This parabolic trough collector can be equipped with a conventional tracking system about one or two motion axes. The positional angle does not matter for the parabolic shape of the ropes 21 as long as the traction means 19 pull the ropes 21 with a force greater than the weight of the ropes 21 and the reflective material 25 and all other acting forces such as, e.g., the wind loads. For tracking about a horizontal axis, the longitudinal axis 5 can be used as the horizontal axis of the tracking system, which is connected to the lower part 7 by supports 4. The entire parabolic trough collector can be attached on a conventional mounting system 6.

(53) The invention is not limited to the illustrated exemplary embodiments, but covers all embodiments within the following patent claims.

REFERENCE LIST

(54) 1 saddle 2 pylon 3 opening 4 support 5 longitudinal axis 6 mounting system 7 lower part 8 threaded rod 9 clamping nut 10 roller 11 tongue 12 rod 13 hole 14 joist 15 longitudinal strut 16 hole 17 absorber holder 18 groove 19 traction means 20 wire rope clamp 21 rope 22 nut 23 wire rope clamp 24 lower parts of the traction means 25 reflector 26 hole 27 symmetry axis 28 aperture 29 focal length 30 hole 31 engagement point 32 support arm 33 deflection rollers 34 clamps