Heliostat

Abstract

A heliostat (1) having a mirror (3), which is fastened to a holding device (5), and having a stand device (7), on which the holding device (5) is mounted rotatably about the azimuth axis of rotation (10) by means of a rotary bearing means (9), characterized in that the rotary bearing means (9) has at least three sliding guide parts (19) which are fastened to the holding device (5) at the same distance from the azimuth axis of rotation (10), the sliding guide parts (19) each having a horizontal guide groove (19a) arranged on the side facing away from the azimuth axis of rotation (10), and in that the stand device (7) has a circular guide ring (21) which is accommodated in the guide grooves of the sliding guide parts (19), the holding device (5) being rotatable with the sliding guide parts (19) about the azimuth axis of rotation (10).

Description

[0001] Heliostat

[0002] The present invention relates to a heliostat with a mirror which is fastened to a holding device and with a stand device on which the holding device is rotatably mounted about the azimuth rotation axis by means of a rotary bearing device.

[0003] Heliostats are sun-tracking mirror systems used to concentrate solar radiation for solar tower systems. Heliostats are typically designed for a service life of approximately 30 years, which places very high demands on accuracy. Since heliostats are exposed to wind loads throughout their service life, maintaining the required accuracy while keeping costs as low as possible is a major challenge.

[0004] The mirror of heliostats is usually tracked to the sun, with a drive around the vertical azimuth axis of rotation and a horizontal elevation axis.

[0005] The bearings along the vertical azimuth axis of rotation must be radial and axial. Combined radial and axial bearings, for example, are quite complex and expensive, especially since they require constant maintenance to prevent corrosion.

[0006] It is also known to use pylons as support structures for heliostats. For the installation of the pylons on the ground, a pile-driving technique can be used, for example, whereby the pylons must have a sufficiently thick wall thickness of at least 4 mm. Such pylons are therefore also comparatively expensive.

[0007] The heliostats described above are part of the applicant's general knowledge, but do not refer to any specific, published prior art.

[0008] It is therefore the object of the present invention to provide a heliostat of the type mentioned above that has a simple and cost-effective design. It is also the object of the present invention to provide a cost-effective method for installing a heliostat on the ground.

[0009] In the heliostat according to the invention with a mirror that is fastened to a holding device and with a stator device on which the holding device is mounted by means of a pivot bearing device so as to be rotatable about the azimuth axis of rotation, it is provided that the pivot bearing device has at least three sliding guide parts that are fastened to the holding device at an equal distance from the azimuth axis of rotation, wherein the sliding guide parts each have a horizontal guide groove arranged on the side facing away from the azimuth axis of rotation, wherein the stator device has a circular guide ring that is received in the guide grooves of the sliding guide parts, wherein the holding device is rotatable with the sliding guide parts about the azimuth axis of rotation.

[0010] The heliostat according to the invention thus provides a pivot bearing device consisting of several sliding guide parts that interact with a guide ring. The guide ring is attached to the stator device and is thus static, whereas the holding device is rotated about the azimuth axis of rotation by means of the sliding guide parts. The pivot bearing device of the heliostat according to the invention is thus of simple construction. Furthermore, a very stable bearing can be created by the guide ring having an appropriate inner diameter and the sliding guide parts being arranged at a correspondingly large distance from the azimuth axis of rotation. The sliding guide parts engage the guide ring from the inside, whereby the reception of the guide ring in the horizontal guide grooves of the sliding guide parts ensures advantageous bearing in the axial direction.

[0011] When using three sliding guide parts, these can be arranged at an angle ß of at least 90° to each other with respect to the azimuth axis of rotation.

[0012] By arranging three sliding guide parts at an angle ß of at least 90° to each other in relation to the azimuth rotation axis, the sliding guide parts can ensure reliable support without the sliding guide parts, and thus the holding device, becoming accidentally detached from the guide ring. The angle of the sliding guide parts in relation to the azimuth rotation axis is measured between a virtual line between the azimuth rotation axis and the center of a sliding guide part and a corresponding virtual line of the adjacent sliding guide part. When using more than three sliding guide parts, the angle ß can also be smaller. For example, the following can apply: angle ß > 180 / (number of sliding guide parts - 1).

[0013] Preferably, the sliding guide parts are arranged at the same angle to each other with respect to the azimuth axis of rotation. For example, if there are three sliding guide parts, they are arranged at an angle of 120° to each other.

[0014] It can be provided that at least one sliding guide part is designed to be movable in a direction towards the azimuth axis of rotation, for example in that the corresponding sliding guide part has an elongated hole through which a screw is passed, by means of which the sliding guide part is fastened to the holding device. This allows the sliding guide part to be moved out of its fastening position, whereby the holding device can be released from the guide ring. For installation, the corresponding sliding guide part is moved into its fastening position, where it engages the guide ring and is fastened by means of the screw. The guide ring can have teeth on which a drive device arranged on the holding device engages. The teeth of the guide ring can be arranged on the outside. For example, the drive device can have a chain drive, with a chain engaging the outer teeth of the guide ring.Of course, other drive mechanisms are also possible, for example, via a pinion that engages the teeth of the guide ring. Since the drive mechanism in this embodiment of the heliostat according to the invention is arranged on the holding device, the drive mechanism is moved along with the holding device when the mirror is pivoted. Therefore, the design of the drive mechanism with a chain drive is particularly advantageous, since the drive mechanism can be advantageously moved around the guide ring together with the holding device.

[0015] The sliding guide parts can have sliding inserts made of a sliding material, whereby the sliding material, together with the guide ring, creates a sliding resistance that exceeds the maximum wind-induced torque. When the mirror is erected, it is exposed to wind, so that a wind-induced torque can act on the mirror. By designing the sliding guide parts with sliding inserts that create a correspondingly high sliding resistance, the wind-induced torque can be prevented from causing an unintentional rotation of the mirror. This makes the pivot bearing assembly virtually play-free.

[0016] The mirror can be raised or adjusted using an elevation drive, which is arranged, for example, on the holding device or acts on it. When the mirror is raised during an elevation movement, the horizontal distance between the mirror's center of gravity and the azimuth axis of rotation can increase, creating a tilting moment. This tilting moment is absorbed by at least some of the sliding guide parts. The increasing tilting moment also increases the sliding resistance between the sliding guide parts and the guide ring, so that as the mirror is raised and the tilting moment increases, the sliding resistance also increases. This is advantageous because as the mirror is raised, it offers a larger surface area for the wind to act on, thus also increasing the wind-induced torque.

[0017] The sliding resistance must of course be overcome when the mirror is driven by the drive device.

[0018] It is preferably provided that the stand device is designed as a pylon.

[0019] The pylon can have a pylon tube with a wall thickness between 0.5 mm and 2 mm, preferably between 0.5 mm and 1 mm. The heliostat according to the invention also allows for pylons with a pylon tube with a larger outer diameter, thus ensuring high stability even with a small wall thickness. For example, the pylon tube can have an outer diameter between 100 mm and 200 mm, preferably 140 mm.

[0020] The pylon tube can be designed as a ramming tube, so that the pylon can be easily installed on the ground without the need for complex foundations.

[0021] The holding device can have horizontal beam supports, to the underside of which the sliding guide parts are attached, with the guide ring being attached to the upper edge of the pylon. The beam supports can, for example, be arranged in a T-shape. A cross member can run parallel to the mirror, whereby the cross member can be connected to the mirror via joints that form the elevation axis. A longitudinal member, which is arranged orthogonally to the cross member, with the longitudinal member and the cross member meeting above the stand device, can serve as the attachment point for the elevation drive. The holding device can also have further supports that connect the mirror to the horizontal beam supports. The guide ring on the upper edge of the pylon can also serve to stabilize the pylon.

[0022] A pylon with a pylon tube can be installed on the ground using the following method. The pylon can, for example, be a pylon of a heliostat according to the invention. The method involves the following steps: a) providing an inner ramming tube with an outer diameter adapted to an inner diameter of the pylon tube and with a wall thickness of at least 3 mm, b) flanging a lower edge of the pylon tube to encompass a lower edge of the inner ramming tube, c) inserting the inner ramming tube into the pylon tube, d) driving the inner ramming tube and pylon tube into the ground, e) withdrawing the inner ramming tube.

[0023] By providing an inner ramming tube that is pushed into the pylon tube, the stability of the pylon tube is increased, so that the pylon tube can be driven even with a pylon tube design with a comparatively thin wall thickness, for example between 0.5 mm and 1 mm. By flanging the lower edge of the pylon tube to encompass the lower edge of the inner ramming tube, it is ensured that when the inner ramming tube and pylon tube are driven into the ground together, the pylon tube is carried along by the inner ramming tube. The pylon tube and the inner ramming tube are driven into the ground with the lower, flanged edge of the pylon tube and the lower edge of the ramming tube in the driving direction. After the inner ramming tube and pylon tube have been driven in, the inner ramming tube can be pulled out, leaving the pylon tube in the ground. This makes it easy to install the pylon tube.

[0024] It may be provided that the soil material inside the pylon tube located in the ground is subsequently compacted.

[0025] The invention is explained in more detail below with reference to the following figures. They show:

[0026] Fig. 1 is a schematic view of a heliostat according to the invention,

[0027] Fig. 2 is a schematic detailed view of the holding device, which is rotatably mounted on the stand device by means of a pivot bearing device,

[0028] Figs. 3a and 3b are schematic representations of the sliding guide parts of the rotary bearing device and

[0029] Fig. 4 is a schematic sectional view of a pylon of the heliostat according to the invention.

[0030] Fig. 1 schematically illustrates the heliostat 1 according to the invention. The heliostat 1 comprises a mirror 3 pivotably mounted on a support device 5. The support device 5 is rotatably mounted on a stand device 7.

[0031] The stand device 7 is designed as a pylon and installed on a floor.

[0032] As can be seen from Fig. 2, the holding device 5 is rotatably mounted on the upper side of the pylon via a pivot bearing device 9. The holding device 5 has beam supports 11 arranged in a T-shape. A cross member 11a is arranged parallel to the mirror 3, and the mirror 3 is fastened to the ends of the cross member 11a by means of joints 13 that form the elevation axis 14. A longitudinal member 11b is arranged orthogonally to the cross member 11a, with the longitudinal member 11b and the cross member 11a meeting above the pylon. An elevation drive 15 is arranged above the holding device 5 and engages one end of the longitudinal member 11b by means of a threaded spindle 17. The elevation drive 15 can move the mirror 3 around the elevation axis 14 and thus erect it.

[0033] As best seen in Figs. 3a and 3b, sliding guide parts 19 are arranged on the underside of the beam supports 11 and interact with a guide ring 21. The sliding guide parts 19, together with the circular guide ring 21, form the pivot bearing device 9. The pivot bearing device 9 allows the holding device 5 to be rotated about the azimuth rotation axis 10, which is arranged in the center of the pylon. For this purpose, the sliding guide parts 19 each have a guide groove 19a, which is formed horizontally on the side of the sliding guide parts 19 facing away from the azimuth rotation axis 10. The sliding guide parts 19 engage the guide ring 21 from the inside and partially accommodate the guide ring 21 in the guide grooves 19a.

[0034] The sliding guide parts 19 are arranged at an angle ß of 120° with respect to the azimuth rotation axis 10. The sliding guide part 19 arranged on the longitudinal member 11b is fastened by means of a screw 19c arranged in a slotted hole, so that the sliding guide part 19 can be displaced in the longitudinal direction of the longitudinal member 11b for assembly.

[0035] The guide ring 21 has a toothing 21a on its outer side, which a drive device 23 engages. The drive device 23 is arranged on the longitudinal member 11b and has a drive pinion 23a (see Fig. 3b, which shows a view from below). A chain drive (not shown) can be driven by the drive pinion 23a, which engages the toothing 21a of the guide ring 21. In this way, the holding device 5 can be advantageously rotated about the pivot bearing device 9.

[0036] The sliding guide parts 19 have sliding inserts 19b made of a sliding material in their guide groove 19a. The sliding material is selected such that, together with the guide ring 21, it forms a sliding resistance that is greater than a maximum wind-induced torque. This ensures that the wind-induced torque cannot unintentionally rotate the mirror 3, so that the drive device 23 can also be designed with a relatively large mirror.

[0037] The pylon of the stand device 7 comprises a pylon tube 25 with a comparatively thin wall thickness of, for example, 0.5 mm. The guide ring 21 is arranged on the upper side of the pylon tube 25 and protects the upper edge of the pylon tube 25 while simultaneously increasing stability.

[0038] The pylon tube 25 can, for example, have an outer diameter of 140 mm.

[0039] To install the pylon tube 25 with a relatively thin wall thickness into the ground using a ramming technique, a ramming tube 100 can be used, as shown in Fig. 4. The ramming tube 100 has an outer diameter adapted to the inner diameter of the pylon tube 25 and is inserted into the pylon tube 25. The lower end 25a of the pylon tube is crimped around the lower edge of the ramming tube 100 or a similar tube. Thus, the pylon tube 25 can be driven into the ground using the ramming tube 100, since the ramming tube 100, which can have a wall thickness of 4 mm, for example, provides the necessary stability.

[0040] 1 heliostat 3 mirrors

[0041] 5 Holding device

[0042] 7 Stand device

[0043] 9 Pivot bearing device

[0044] 10 Azimuth rotation axis 11 Beam support

[0045] 11a Cross member lib Longitudinal member 13 Joints 14 Elevation axis 15 Elevation drive 17 Threaded spindle 19 Sliding guide parts

[0046] 19a Guide groove 19b Sliding inserts 19c Screw 21 Guide ring 21a Toothing 23 Drive device 23a Drive pinion

[0047] 25 pylon tube 25a end 100 ram tube

Claims

Patent claims 1. Heliostat (1) with a mirror (3) which is fastened to a holding device (5), and with a stand device (7) on which the holding device (5) is mounted so as to be rotatable about the azimuth rotation axis (10) by means of a pivot bearing device (9), characterized in that the pivot bearing device (9) has at least three sliding guide parts (19) which are fastened to the holding device (5) at an equal distance from the azimuth rotation axis (10), wherein the sliding guide parts (19) each have a horizontal guide groove (19a) arranged on the side facing away from the azimuth rotation axis (10), and in that the stand device (7) has a circular guide ring (21) which is received in the guide grooves (19a) of the sliding guide parts (19), wherein the holding device (5) is rotatable with the sliding guide parts (19) about the azimuth rotation axis (10).

2. Heliostat according to claim 1, characterized in that the sliding guide parts (19) are arranged at the same angle ß to one another with respect to the azimuth rotation axis (10).

3. Heliostat according to claim 1 or 2, characterized in that the guide ring (21) has a toothing (21a) on which a drive device (23) arranged on the holding device (5) engages.

4. Heliostat according to claim 3, characterized in that the toothing (21a) is arranged on the outside of the guide ring (21).

5. Heliostat according to claim 4, characterized in that the drive device (23) has a chain drive with a chain, the chain engaging the toothing (21a).

6. Heliostat according to one of the preceding claims, characterized in that the stand device (7) is designed as a pylon.

7. Heliostat according to claim 6, characterized in that the pylon comprises a pylon tube (25) having a wall thickness between 0.5 mm and 2 mm, preferably between 0.5 mm and 1 mm.

8. Heliostat according to claim 7, characterized in that the pylon tube (25) has an outer diameter between 100 mm and 200 mm.

9. Heliostat according to claim 7 or 8, characterized in that the pylon tube (25) is designed as a ram tube.

10. Heliostat according to one of the preceding claims, characterized in that the holding device (5) has horizontal beam supports (11), to the underside of which the sliding guide parts (19) are fastened, the guide ring (21) being fastened to the upper edge of the pylon.

11. Heliostat according to one of the preceding claims, characterized in that the sliding guide parts (19) have sliding inserts (19b) made of a sliding material, wherein the sliding material forms a sliding resistance with the guide ring (21) which is greater than a maximum wind-induced torque.

12. A method for installing a pylon having a pylon tube (25), preferably a heliostat according to one of claims 6 to 10, into a ground, comprising the following steps: a) providing an inner ramming tube (100) with an outer diameter adapted to an inner diameter of the pylon tube (25) and with a wall thickness of at least 3 mm, b) flanging a lower edge of the pylon tube (25) to encompass a lower edge of the inner ramming tube (100), c) inserting the inner ramming tube (100) into the pylon tube (25), d) ramming the inner ramming tube (100) and pylon tube (25) into the ground, and e) pulling out the inner ramming tube (100).

13. The method according to claim 12, characterized by the further step: f) compacting soil material inside the pylon tube (25) located in the ground.

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