Multiple wall connection over piers

Abstract

A solar tracker including at least one pair of piers configured to be secured in the ground and defining a span between the pair, a bearing supported on the pier, and a torque tube supported in the bearing such that the bearing enables rotation of the torque tube, the torque tube including a double wall thickness area, wherein the double wall thickness area limits deflection of the torque tube along the span.

Claims

1. A solar tracker, comprising: at least one pair of piers configured to be secured in the ground and defining a span between respective piers of the at least one pair of piers; a bearing supported on a pier of the at least one pair of piers; a torque tube rotatably supported in the bearing, the torque tube including a double wall thickness area, the double wall thickness area including a sleeve inserted into the torque tube, wherein the double wall thickness area limits deflection of the torque tube along the span; and a drive system operably coupled to the torque tube, wherein the drive system effectuates rotation of the torque tube within the bearing as the solar tracker follows an orientation of the sun.

2. The solar tracker of claim 1, wherein the torque tube has a single wall thickness outside of the double wall thickness area.

3. The solar tracker of claim 1, wherein the double wall thickness area is centered on each pier.

4. The solar tracker of claim 1, wherein the torque tube is formed of at least two sections.

5. The solar tracker of claim 4, wherein the double wall thickness area is centered on a joint connecting the at least two sections of the torque tube.

6. The solar tracker of claim 4, wherein one of the at least two sections includes a reduced diameter portion configured to be received within the second section to form the double wall thickness area of the torque tube.

7. The solar tracker of claim 6, wherein the reduced diameter portion is swaged to reduce the diameter of the torque tube at the reduced diameter portion.

8. The solar tracker of claim 1, wherein the double wall thickness area is formed at high load areas of the torque tube.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various aspects of the present disclosure are described hereinbelow with reference to the drawings, which are incorporated in and constitute a part of this specification, wherein:

(2) FIG. 1 is a side view of a solar tracker;

(3) FIG. 2 is a side view of a pier and bearing supporting a torque tube in accordance with the disclosure;

(4) FIG. 3 is a side view of a pier and bearing supporting a torque tube in accordance with the disclosure;

(5) FIG. 4 is a perspective view of a wall reinforcement in accordance with the disclosure;

(6) FIG. 5A is a side view of a wall reinforcement mounted in a bearing in accordance with the disclosure;

(7) FIG. 5B is a perspective view of a wall reinforcement mounted in a bearing in accordance with the disclosure;

(8) FIG. 6A is a side view of a wall reinforcement mounted in a bearing in accordance with the disclosure; and

(9) FIG. 6B is a perspective view of a wall reinforcement mounted in a bearing in accordance with the disclosure.

DETAILED DESCRIPTION

(10) The present disclosure describes a system and method for locally increasing the rigidity of a torque tube of a solar tracker proximate a connection point to a pier to reduce deflections of the torque tube and enable decreased size of the torque tube.

(11) FIG. 1 depicts a side view of a solar tracker 10. The solar tracker 10 includes a drive system 12, which may be for example a slew gear drive driven by an electric motor, or other drive mechanism as is known in the art. Connected to the drive system 12 is a torque tube 14. The torque tube 14 typically consists of a round or square cross-section galvanized steel pipe. Of course, those of skill in the art will recognize that other materials may be employed if determined to be cost effective. The torque tube 14 is carried in a series of bearings (not shown in FIG. 1). The bearings and therewith the torque tube 14 are carried by a series of piers 16.

(12) The loads 18 caused by the solar panels and rails (not shown) are borne by the torque tube 14. As can be observed by the flexure line 20, where the loads 18 correspond to the locations of the piers 16, the deflection of the torque tube 14 is minimized. In contrast, in span 22 between the piers 16 the deflection of the torque tube 14 is the greatest. Though the maximum deflection is experienced mid-span 22, the highest bending moment, which results in the deflection, is experienced at the piers 16. Thus, the piers represent high load areas of the torque tube 14.

(13) In traditional solar tracker design, the entire torque tube 14 is simply increased in diameter and wall thickness upsized in order limit the deflection between the piers 16 to within a design tolerance. This results in more material added to the entire length of the tracker 10. The additional material results in added weight, to the entire tracker 10 requiring additional power to drive the solar tracker 10 as it follows the sun. Further, the additional material results in increasing costs for the solar tracker 10. This disclosure is directed a system and method of absorbing the bending moment where the capacity is only needed in about half to one-meter sections directly over piers.

(14) FIG. 2 depicts one aspect of the disclosure. In FIG. 2 the solar modules 24 are connected on their ends to rails 26, which are secured to the torque tube 14. Between the rails 26 is a bearing 28. The torque tube 14 is received in the bearing 28, and the bearing 28 allows the torque tube 14 to rotate as the solar tracker 10 follows the sun. The bearing 28 connects to a support 30 which mechanically connects to the pier 18. As shown in FIG. 2 the torque tube 14 is formed of multiple sections. A first section 14a of the torque tube 14 includes a first diameter portion 15a and a second diameter portion 15b. The first diameter portion 15a is larger than the second diameter portion 15b. A second section 14b of the torque tube includes at least a portion 15a that corresponds in diameter with section 15a of the first section 14a and which is sized to receive the second diameter portion 15b of section 14a. As depicted in FIG. 2 the torque tube has a round cross-section, however, this same configuration can be achieved in torque tubes having square, rectangular, triangular, and other cross-sections without departing from the scope of the disclosure.

(15) During the manufacturing process the second diameter portion 15b of the first section 14a of the torque tube 14 is swaged to achieve the reduced diameter of the second diameter portion 15b. This reduced diameter portion 15b of the first section 14a is received within the second section 14b of the torque tube 14. The first and second sections 14a and 14b are secured together with fasteners 31. The result is that in the portion of the torque tube 14, wherein the reduced diameter portion of the first section 14a is received within the second section 14b, the combined wall thickness of the torque tube 14 creates a doubled wall thickness area 32. As can be seen in FIG. 2, the area of doubled wall thickness 32 is centered on the pier 16 (e.g., at high load areas). In this way, the bending moment can be better borne at the locations where it is highest, proximate the piers 16. The swaged or reduced diameter portion 15b of first section 14a, and thus the double wall thickness area 32 may be, for example between one half and one meter in length, though longer lengths are also contemplated within the scope of the disclosure.

(16) As a consequence of creating the doubled wall thickness area 32 of the torque tube 14 directly over the piers, the overall thickness of the material of the torque tube 14 can be reduced. Further, because the thickness of the torque tube 14 is typically associated with the diameter of the torque tube 14, the overall diameters may also be reduced. Further, because of the increased stiffness, longer sections 14a, 14b can be employed, which further or alternatively reduces the overall material usage and costs of the solar tracker 10.

(17) An alternative arrangement, achieving similar results can be seen with respect to FIG. 3. In FIG. 3 the torque tube 14 has a uniform diameter along its entire length. Rather that swaging the first portion of the torque tube 14a to be received within the second portion 14b of the torque tube 14, a sleeve 34 is inserted into the torque tube 14. The sleeve 34 is centered on a joint location 36 between two adjacent portions of the torque tube 14. The connection point may be maintained some distance from the pier 16 to assist in easing construction. The sleeve 34 extends through the bearing 28 and creates a double walled area 32 centered on the pier 16. The double walled area 32 achieves a similar function as double walled area 32 in FIG. 2. The sleeve 34 acts as a tube splice effectively joining two sections 14a and 14b of the torque tube 14.

(18) FIG. 4 depicts a further alternative solution in accordance with the disclosure. The solution in FIG. 4 is wall reinforcement 40 formed of two doubler plates 41. The doubler plates 41 may have a U-shaped configuration such that they mate with the torque tube 14 and the torque tube 14 is received within the U-shape. The doubler plates 41 include a plurality of flanges 42. The flanges 42 include holes formed therein to allow for the passage of fasteners 44. As shown in FIG. 4, the fasteners 44 are U-bolts. The open end of the U-bolts may be received in a strong back 46 and a nut 48 threaded on a threaded section of the U-bolt. Notches 50 can made with notches formed in a torque tube 14 to prevent axial movement of the wall reinforcement 40 relative thereto.

(19) The wall reinforcement 40 further reduces the amount of material necessary to limit the bending moment. This reduction in material is achieved by only placing the doubler plates 41 on the bending axis of the torque tube 14. The fasteners 44 span the neutral axis of the torque tube 14, and thus no double plates are needed on that side of the torque tube 14.

(20) FIGS. 5A and 5B depict a particular implementation of wall reinforcement 40 in a balanced bearing 28. The balanced bearing 28 is modified to allow the torque tube 14 to be driven by a distributed drive system. The distributed drive system includes a gear box 52. The gear box 52 is operably connected on one end to a screw mechanism 54 which employs a threaded rod to extend and retract, thus rotating the torque tube 14. The gear box 52 receives a shaft 56 which extends between the piers 16 and allows a single motor (not shown) to drive all of the gear boxes 52 along the length of the solar tracker 10. In both FIGS. 5A and 5B, the wall reinforcement 40 is sized and shaped to receive within the bearing 28, and over the pier 16. Thus, the location of the wall reinforcement 40 is substantially similar to the double wall area 32 of FIGS. 2 and 3. In FIGS. 5A and 5B, the wall reinforcement 40 is located on a top and bottom portion of the torque tube when the solar tracker 10 is in the 0? position or substantially perpendicular to the piers 16. Alternatively, the wall reinforcement 40 may be located such that the doubler plates 41 are placed on the sides of the torque tube 14 when the solar tracker is in the 0? position or substantially perpendicular to the piers 16.

(21) The thickness of the doubler plates 41 may be thickened as necessary for a given application. Similarly, the length of the doubler plates 41 may be increased or reduced as necessary to effectively reduce the effects of the bending moment such that torque tube 14 remains substantially straight and without damaging deflections to the torque tube 14.

(22) Additionally, the wall reinforcement may be placed at any location a pier 16 is needed, and need not be located at or proximate a joint location 36, as depicted in FIGS. 2 and 3. Nonetheless, the wall reinforcement 40 can be employed to reduce the thickness of the torque tube 14 and to provide the additional thickness and stiffness for the torque tube at the location of the highest bending moment (i.e., over the piers 16) the thickness and in some instances diameter of the torque tube 14 may be reduced. Further, by increasing the stiffness at the piers 16, to total number of piers 16 in a solar tracker 10 may be reduced.

(23) It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as an exemplification of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure. Such modifications and variations are intended to come within the scope of the following claims.