Abstract:
The invention relates to an alignment and/or tracking device ( 1 ) for solar collectors (x), comprising a plurality of pivot axles (S) on each of which a plurality of solar collectors ( 5, 5 ′) are mounted, and a jointly acting adjustment device ( 6, 7, 8 ) which couples the pivot axles (S) to one another in such a way that the pivot axles (S) are jointly pivotable. The alignment and/or tracking device according to the invention is characterised in that the adjustment device ( 6, 7, 8 ) is coupled to each of the pivot axles (S) by at least one articulation joint (GL), in particular a universal joint.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to an alignment and/or tracking device for solar collectors according to the preamble of independent claim  1 . 
       PRIOR ART 
       [0002]    Conventional collector arrays are aligned in a simple design to a central position of the sun which, however, has significant disadvantages as a result of the changing position of the sun over the course of the day and seasons. Improved systems may have, for example, column supports which have a “tracking” function for tracking according to the position of the sun which changes over the course of the day. For example, WO 2009/015221 A2 thus discloses a known tracking system for solar collectors. 
         [0003]    Such column supports with tracking systems are relatively expensive to manufacture and involve a relatively high maintenance outlay in terms of installation and operation. They are also regarded as relatively prone to faults since a plurality of movable mechanical parts is exposed to the elements. 
         [0004]    Moreover, the applicant is aware of alignment and tracking devices according to the preamble of claim  1 . These, however, have the disadvantage that they can only be erected on flat ground or complex measures are required in the case of changeable terrain topography, such as, for example, compensated foundations, flattening work or the like. It should be noted here that, for example, the flattening work cannot or may not be carried out in all areas. 
       EXPLANATION OF THE INVENTION 
       [0005]    The primary objective of the present invention is to make available a simple and low-cost system for aligning and tracking solar collectors to a changing position of the sun, which system is largely independent of the ground and the formation of the terrain. 
         [0006]    This objective of the invention is achieved with the subject matter of the independent claim. Features of advantageous further developments of the invention will become apparent from the dependent claims. 
         [0007]    In order to achieve the stated objective, the invention proposes a generic alignment and/or tracking device for solar collectors in the case of which the adjustment device is coupled to the pivot axles in each case via at least one articulated joint, in particular a cardanically acting articulated joint. The articulated joint makes it possible to even out angle deviations which may arise, for example, from the terrain topography. As a result, the alignment and/or tracking device according to the invention can be used on practically any terrain and, despite changeable terrain topography, enable an adjustment of the pivot axles which is adapted to the incident solar radiation. All this is achieved with a comparatively simple construction. 
         [0008]    According to a further development of the invention, it is provided that at least one pivot axle has at least two carrying elements, between which a connecting articulated joint, in particular a cardanically acting connecting articulated joint, is arranged. As a result of this, an even better capacity for adjustment to different terrain topographies can be achieved. 
         [0009]    Moreover, according to a further development of the invention, it is provided that the pivot axles are supported on support elements, wherein a support articulated joint, in particular, a separable ball joint, is provided between the pivot axles and at least a few support elements. As a result of this, a particularly stable system can be provided which can be aligned and tracked at the same time without constraining forces and precisely. 
         [0010]    The adjustment device has, according to a further development of the invention, at least one pivot drive which operates, for example, hydraulically or electromotorically. Hydraulic pivot drives have the particular advantage here that they are also suitable for continuous application of a drive force without energy being permanently consumed. This is particularly important in the case of the highly continuous alignment and tracking operations. 
         [0011]    Although it is in principle possible that only one individual pivot drive is provided, it is provided according to a further development of the invention that the adjustment device has two pivot drives which are arranged at opposite ends of the adjustment device and preferably act in opposite directions. As a result of this particular configuration, it becomes possible to significantly simplify the construction of the alignment and tracking device according to the invention. It is thus, for example, possible to effect the transmission of the drive forces which come from the pivot drives exclusively or at least primarily via tension elements (e.g. wires or rods) so that complex and heavy pressure or bending elements can be largely omitted. 
         [0012]    Against this background, it is provided according to a further development of the invention that the adjustment device has a control device which is set up to control the pivot drives in such a manner that connecting elements of the adjustment device are always tensioned at least in operation. 
         [0013]    According to a further development of the invention, it is furthermore provided that the adjustment device has a plurality of adjusting lever units, wherein in each case a rod-shaped element, in particular a traction means, is provided between two adjacent adjusting lever units. As a result of this, a reliable and at the same time simple construction which can also be mounted quickly is produced with a small number of structural units which can be premanufactured in large quantities without any problems. It is particularly advantageous here that the adjusting lever units in each case have one adjusting lever which couples the adjustment device to the assigned pivot axle. As a result, small adjustment forces and precise adjustability or precise alignment and tracking operation are produced. 
         [0014]    According to a further development of the invention, it is furthermore provided that at least one adjusting lever unit has a restoring means, in particular a spring, in order to actuate the respective adjusting lever in the direction of a starting position. As a result of this, the torques which are generated in the course of the alignment and tracking operation and primarily result from the dead weight of the solar collectors can be reduced or absorbed. This results in a reduction in the adjustment forces and thus a significant relief of load on the drives which can then potentially be configured to be more compact and with less power. Moreover, these torques do not have to be introduced in the support construction and foundations. As a result of this, the corresponding components can be significantly simplified—up to the anchoring in the ground. Moreover, fewer deformations occur in the overall system. 
         [0015]    According to a further development of the invention, it is furthermore provided that the adjustment device has articulated joints, preferably ball heads, in particular in the region of a connection between adjusting lever units and rod-shaped elements. As a result of this, an adjustment operation free of constraint is produced without complex components being necessary. 
         [0016]    Exemplary embodiments are intended to explain the invention and its advantages in greater detail below on the basis of the enclosed figures. The size ratios of the individual elements to one another in the figures do not always correspond to the real size ratios since several shapes are simplified and other shapes are shown in an enlarged form in comparison to other elements for the sake of clarity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  shows the basic structure of a “horizontal tracker”. 
           [0018]      FIG. 2  shows a section along a pivot axle of the tracker in accordance with  FIG. 1 . 
           [0019]      FIG. 3  shows a further section, but without the collector surfaces. 
           [0020]      FIG. 4  shows the structure of the drive of the pivot axles on the terrain. 
           [0021]      FIG. 5  shows a drive station which is mounted on a ground anchor. 
           [0022]      FIG. 6  shows a pivot station. 
           [0023]      FIG. 7  shows a region on one side of a drive or pivot station with connected carrying element  9 . 
           [0024]      FIG. 8  shows a section through the pivot axle of a drive or pivot station. 
           [0025]      FIG. 9  shows a detailed view of the structure of the articulated joint bearing region in section. 
           [0026]      FIG. 10  shows the articulated joint bearing region in a separated form. 
           [0027]      FIG. 11  shows the further structure of a pivot station. 
           [0028]      FIG. 12  shows a separable ball joint. 
           [0029]      FIG. 13  shows a connecting articulated joint. 
           [0030]      FIG. 14  shows a bearing point with the ball joint in the profile of a linear pivot axle. 
           [0031]      FIG. 15  shows the formation of a bearing point with the ball joint and connecting articulated joint in a curved pivot axle. 
           [0032]      FIG. 16  shows a nut basket which serves the purpose of simple and rapid mounting of the pivot axles. 
           [0033]      FIG. 17  shows the nut basket in the case of a linear connection. 
           [0034]      FIG. 18  shows a terrain profile with several collectors. 
           [0035]      FIG. 19  shows an alternative configuration of a pivot station in a side view. 
           [0036]      FIG. 20  shows a perspective view of the pivot station shown in  FIG. 19 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0037]      FIG. 1  shows the basic structure of a “horizontal tracker”  1 , i.e. of an alignment and/or tracking device  1 , on an uneven terrain formation  2 . Horizontal tracker  1  is only partially constructed and drawn here for the sake of clarity so that only one pivot axis S with panels and one region of drive A are visible. 
         [0038]    Pivot axle S preferably runs in a North-South direction and is, according to the invention, pivoted by approx. +/−45°. The drive region generally lies centrally in the East-West direction. The dimensions of a unit can be, for example, up to 60 m by 120 m. An adjustment to the terrain or its formation and/or inclination is thus also generally required. 
         [0039]      FIG. 2  shows a section along a pivot axle S with a linear region H, occupied by solar collectors  5 , and a curved region G with solar collectors  5 ′. Narrow drive region A is located therebetween. Pivot axles S are generally elevated on ground anchors  4  on ground  3 . It becomes apparent in the case of the linear side that the distance from occupation (solar collectors  5 ) to ground h2 increases as a result of the gradually falling terrain. In contrast, in curved region G, the distance from occupation (solar collectors  5 ′) to ground h1 remains approximately the same. It is advantageous if the distance to the ground does not change since it is then always possible to operate with ground anchors of equal length and the panels are also easier to access for maintenance work. 
         [0040]      FIG. 3  practically again shows the same section as in  FIG. 2 , but without being occupied, i.e. without collector surfaces  5 ,  5 ′. As a result, the profile of pivot axles S1 and S2 becomes clearer. Linear pivot axle S1 in linear region H can only be rotated at drive region A about an angle ω since a pivoting bearing is located at the drives. Curved pivot axle S2 in curved region G is divided here, for example, into three portions g1, g2 and g3 which are then, depending on the requirement, rotated by specific angles Φ at the drive, an angle α between g1 and g2 and an angle β between g2 and g3 in such a manner that they follow terrain contour  3 . The curved pivot axle is slightly more expensive so that it may not have to be used in the case of even terrain. The system enables both variants which are to be combined with one another in any desired manner. 
         [0041]      FIG. 4  shows the structure of the drive of pivot axles S on the terrain. It is decisive here that there sits in each case at the end of the drive distance (here 3×distance D) a drive unit with an adjustment lever upwards  6  and operating in each case under tension. The pivot units located therebetween with pivot lever upwards  7  are also actuated by traction means  8 . Pivot angles SW are generally ±45°. If the drive is pulled in one direction, the pulled drive is held with a residual force against the pulling drive, as a result of which the system of traction means  8  is reliably kept tensioned. Up until standstill, both outer sitting drives build up a minimum tension force in order to fix the system. The number of pivot units between the drives (here only 2) can of course be much higher. If the lateral drives are activated hydraulically, the connection and actuation of both sides can proceed either via a hydraulic line. 
         [0042]    A more expedient variant provides an actuation of both sides via an electric control unit so that these two sides are only connected by cable. A radio control unit would also be possible. A tensioned system has the advantage above all in the event of a storm that vibrations do not build up so easily. 
         [0043]      FIG. 5  shows a drive station  6 , mounted on a ground anchor  4 . It is possible to see pivot lever  11 , which rotates about pivot axle S, or forms pivot axle S between the bearing points. Pivot lever  11  is moved by dual-acting hydraulic cylinder  10 . Outbound traction element  8  is also apparent here. It is furthermore shown how carrying elements  9 , here a square tube at articulated joint regions GL, which also form the bearing, are connected. The hydraulic cylinder could also be replaced by a spindle motor. The drive unit also forms the fixed bearing for complete pivot axle S since all the other bearing points must be embodied as loose bearing points in order to be able to accommodate the unavoidable thermal changes in length. 
         [0044]      FIG. 6  shows a pivot station  7 , of which several are constructed between two drive stations  6  (see  FIG. 4 ). For the sake of clarity, one side wall of the frame is not represented, as a result of which pivot lever  11  and traction elements  8  proceeding therefrom are apparent. Otherwise, pivot station  7 , like drive station  6 , is constructed on a ground foundation  4  and is constructed substantially from the same components except for the hydraulic cylinder and its support. For reasons of production engineering and in order to reduce costs, as many identical components as possible are used in the assemblies. 
         [0045]      FIG. 7  shows region GL on one side of a drive or pivot station  6 / 7  with a connected carrying element  9 . Articulated joint ring  13 , which practically forms a cardanic bearing, in which it itself is connected in bearing ring fork  14  and accommodates carrying element  9  via bearing straps  12  can be seen here. The bearing ring with fork  14  is connected to pivot lever  11 ; these parts thus form pivot axle S. Retaining plates  15  ensure axial securing. As a result of this connection, both the linear and the curved pivot axle can be fitted at an angle on the pivot or drive station generally constructed vertically. 
         [0046]      FIG. 8  shows a section through pivot axle S of a drive or pivot station. Both side plates  17 , which are connected at the bottom via base plate  18 , can be seen here. Pivot lever  11  together with both articulated joint bearing regions GL form pivot axle S. 
         [0047]      FIG. 9  once again shows in detail the structure of the articulated joint bearing region in section. Articulated joint bushes  16 , which are used to connect articulated joint ring  13  and the bearing ring with fork  14  or fork straps  12 , can be seen here. Flange screws  20  and nuts  21  are expediently used for the purpose of fastening. A bearing bush  19  is also used here in order to reduce the friction in the haunch of the bearing diameter in side wall  17 . Bearing bush  19  is also required to avoid corrosion in the bearing. 
         [0048]      FIG. 10  shows the articulated joint bearing region in a separated form and thus once again the individual components pivot lever  11 , articulated joint straps  12 , articulated joint ring  13 , bearing ring with fork  14 , retaining plates  15 , articulated joint bushes  16 , side plate  17 , base plate  18  and bearing bush  19 . A simple production method was ensured in the case of all the parts; the bearing ring can be expediently produced e.g. as a forged part. The bearing straps are merely flat laser or stamped parts, likewise the retaining plates. The bearing ring with fork can likewise be manufactured in a stamping tool. 
         [0049]      FIG. 11  shows the rest of the structure of a pivot station or—like here—drive station. Side plates  17  are embodied such that base plate  18  and cover  22  can also be swapped over and installed and thus the alignment of pivot levers  11  to the top or the bottom is possible. The extension arm or cylinder support 23 and hydraulic cylinder  10  are only required for the drive stations. Where possible, identical parts and high flexibility were also ensured here. 
         [0050]      FIG. 12  shows as a further key element for the optimized horizontal tracker a dividable ball joint  24  with a receiving diameter (here square) for the carrying elements. It comprises a base plate  25  with elongated holes L which serve to even out structural tolerances in the horizontal direction. Both ball halves  26 , ball socket halves  27  and intermediate web  28  are furthermore apparent. Flange screws  29  and nuts  30  are used to connect the parts. As a result of the ability to separate the bearing, the carrying elements can be fitted on and do not have to be pushed through which involves a significant outlay in a case of a length up to 12 m. Moreover, where necessary, the bearings can be replaced without having to disassemble other components. The design of the ball sockets could also have other dividing planes which does not change the principle. 
         [0051]      FIG. 13  shows a connecting articulated joint  31  in which all the components from articulated joint region GL are once again found, such as articulated joint ring  13  and articulated joint straps  12 . A new additional element is double fork  32 . The connecting articulated joint is used for the articulated connection of two carrying elements in the curved pivot axle. A clear principle of identical parts also applies here. 
         [0052]      FIG. 14  shows the formation of a bearing point with ball joint  24  in the course of a linear pivot axle S  1 , carrying elements  9  (here square tubes) are only connected to two straight connectors  35  (flat plates). Ball joint  24  is constructed on a ground anchor with flange plate  33 . The flange plate of ground anchor  33  also has elongated holes L for accommodating structural tolerances in the vertical. The flange plate could also be a screw part which is screwed e.g. onto commercially available screw foundations. Elongated holes L are, in the case of a welded variant, preferably as long as half the thread pitch of the screw foundation. In this case, the plate can be stopped from moving during rotation in the position at right angles to the pivot axle. The precise height adjustment is then carried out via the elongated hole. 
         [0053]      FIG. 15  shows the formation of a bearing point with ball joint  24  and connecting articulated joint  31  in a curved pivot axle S2, comprising portions S2a and S2b which are curved by an angle α to one another. The function of ball joint  24  as a supporting element for carrying elements  9  is the same as in  FIG. 14 . The ball joint and the connecting articulated joint also accommodate, in addition to the pivot axle curvature corresponding to the terrain, all the other alignment errors as a result of structural tolerances and ensure smooth and even running of the tracking device. 
         [0054]      FIG. 16  shows a nut basket  36  which serves the purpose of simple and rapid mounting of the pivot axles. It positions the required nuts in the carrying element (here for square tube). To this end, the required number of nuts  38  is inserted in a carrier element  37  which is preferably produced from elastic material. Height guides F and stop edges K are integrated for height guidance. The carrier element can be produced at low cost as an injection moulded part in one plane and only then folded to form a U. The element could also be automatically fitted with nuts in advance and in situ on the building site only the baskets are pushed in. The number of nuts can of course vary; shapes e.g. for round tubes are also conceivable. 
         [0055]      FIG. 17  once again shows the use of nut basket  36 , here at a linear connection. A carrying element  9  is not shown here in order to make the position of nut basket  36  visible. As a result of the uniform configuration of the connections for the carrying elements (here square tubes), the nut basket can be used in all cases. 
         [0056]      FIG. 18  again shows a positive side effect of an upwards orientation of the pivot levers. As a result of narrow structural widths AB, the heights of pivot axles HS are also not very high. This leads in the case of pivot arms aligned downwards (drive and pivot stations  6 ′ and  7 ′) to very low passage heights HDu which is highly insufficient for caring for the land. With drive and pivot stations  6  and  7  (pivot arms aligned upwards), the passage height is increased to HDo while having the same height of pivot axles HS. It can often at least be ensured that tractors can drive through in order to care for the land. The aspect of care, in particular soil and plant care, in a solar energy plant is often neglected, wherein installed and excessively low constructions can only be looked after with difficulty and often only by hand which leads to high unexpected additional costs. 
         [0057]      FIG. 19  shows a side view of an adjusting lever unit  7  according to an alternative embodiment. A perspective view of said adjusting lever unit  7  is shown in  FIG. 20 . Said adjusting lever unit  7  is characterised in that it has springs  41  which are set up to act upon actuating lever  40  in the direction of its respective starting position. For this purpose, springs  41  are connected on the one hand to actuating lever  40  and on the other hand via connecting means  42  to the housing of adjusting lever unit  7 .  FIG. 19  shows actuating lever  40  in its starting position and  FIG. 20  shows actuating lever  40  in its position deflected in one direction. In this position, springs  41  act upon the actuating lever in the direction of its starting position according to  FIG. 19 . As a result of this, torques resulting from the dead weight of solar collectors  5 ,  5 ′ are absorbed so that the pivot drives need to provide less drive power. 
         [0058]    The invention has been described with reference to a preferred embodiment. It is, however, conceivable for a person skilled in the art to be able to make modifications or changes to the invention without departing from the scope of protection of the following claims.