WO2013040322A2

WO2013040322A2 - Solar tracker

Info

Publication number: WO2013040322A2
Application number: PCT/US2012/055358
Authority: WO
Inventors: Michael H. Redler
Original assignee: Redler Michael H
Priority date: 2011-09-15
Filing date: 2012-09-14
Publication date: 2013-03-21
Also published as: WO2013040322A3

Abstract

A post-mounted prime mover for maintaining an efficient alignment of an array of solar panels with respect to the azimuth position of the sun during its diurnal cycle is arranged to permit retrofitting of a preexisting fixed-position solar array without the disassembly or removal of the solar array. The post-mounted prime mover may include an eccentrically oriented drive system which places the majority of its components away from the solar array and allows a greater range of motion during adjustment to the elevation position of the array. The post-mounted prime mover may be backward driven and permitted to move in response to an externally applied force due to inclement weather or other environmental effects.

Description

SOLAR TRACKER

RELATED APPLICATIONS

This application claims the benefit of the filing date under 35 U.S.C. § 119(e) of U.S. Provisional Application Serial No. 61/535,020 filed September 15, 2011, hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to a device that rotates an assembly, and more particularly to a device that rotates a solar energy collection device.

DISCUSSION OF RELATED ART

The value of solar energy as a viable alternative to fossil fuels is becoming increasingly apparent by the growth and trends of a maturing solar market. As solar panel installations increase, the issue of where to use them becomes increasingly important. The cost per unit of installed power typically drives the solar market. The area utilized per unit of power drives a discussion of broader economic value, such as whether solar arrays are a practical application with respect to terrain, geographic location and available space.

Prime movers of the type discussed herein are typically part of a larger, all- inclusive solar tracking system and are typically designed with such a system in mind. In post-mounted systems, the prime mover for a tracking system is mounted on the post first, followed by the solar collection device, such as a photovoltaic panel, a thermal collection device, or a reflection panel. Static solar arrays are often installed in much the same way. The result is an industry which is largely unresponsive to retrofitting static systems with solar trackers, because the retrofitting typically requires a significant dismantling and reassembly effort before and during installation.

Prime movers which are used to respond to commands from a tracking control system have remained largely unchanged despite the various ways in which information about the apparent position of the sun is collected and used. One component often found in prime movers is known as a slew drive. Slew drives have typically served a dual purpose in the renewable energy industry both as a mechanism for mechanically positioning solar collection apparatus for tracking the sun, and as a mechanism for orienting wind turbine nacelles for the similar purpose of optimizing wind power conversion. They are very stout power transmission devices, typically made of a worm and worm gear combination encased in a steel housing. Such a device accepts power rotating along one axis and delivers power along an axis positioned at a right angle to the input axis. Slew drives also convert power from one which is represented by high revolutions per minute and low torque to power represented by low revolutions per minute and high torque. The combination of high stability and high torque output characteristics has made slew drives popular for conventional systems which are intended to maintain a rigid position and withstand relatively high external forces without mechanical failure. There is a significant cost in meeting the precise engineering requirements needed for slew drives, even when produced in high volumes.

Another known prime mover is known as a linear actuator which typically includes a telescoping cylinder and piston arrangement which delivers linear motion. Linear motion is often achieved by converting rotating motion from an electric motor. Linear actuators are not limited to this method and, as seen on countless examples of excavating machinery, linear actuators can also be driven exclusively by fluid power.

As is the case with slew drives, linear actuators are often designed in such a way that they resist or prohibit movement from an external force. And as with many examples of such drives, there is a limit to the external stress which these devices can tolerate. When that limit is surpassed, failure likely occurs. These modes of failure present a significant risk irrespective of the investment made to strengthen the devices. To reduce the probability of mechanical failures, devices are designed and manufactured to be capable of withstanding high stresses and strains. As a result, the cost can easily limit the economic viability of an overall tracking system.

SUMMARY

According to one embodiment, an apparatus for positioning a solar energy collection device includes a first rotator to rotate a solar energy collection device, the first rotator having an opening to receive a carrying member which carries the solar energy collection device. The first rotator further includes an engagement member to engage the carrying member. When the engagement member engages the carrying member, the carrying member is offset from a center of the first rotator According to another embodiment, an apparatus includes a first rotator to rotate a solar energy collection device, the first rotator being configured to engage with a rotatable carrying member which carries the solar energy collection device, and the carrying member having an axis of rotation. With the first rotator engaged with the carrying member, the axis of rotation of the carrying member is offset from an imaginary axis which passes through a center of the rotator and is parallel to the axis of rotation.

According to a further embodiment, an apparatus for positioning a solar energy collection device includes a first engagement member to attach the apparatus to a support member such that the support member supports the apparatus. The apparatus also includes a rotator supported by the first engagement member. The rotator includes a second engagement member to attach the apparatus to a carrying member. The carrying member carries the solar energy collection device and being rotatable relative to the support member to rotate the solar energy collection device relative to the support post when the first engagement member is attached to the support member and the second engagement member is attached to the carrying member. With the first engagement member attached to the support member and the second engagement member is attached to the carrying member, the apparatus permits movement of the carrying member relative to the support member.

According to another embodiment, a rotatable solar collection device support assembly includes a support member and a carrying member supported by the support member, the carrying member configured to carry a solar collection device. The support assembly further includes a rotator configured to rotate the carrying member relative to the support member. The carrying member is movable relative to the support member in a direction which is not parallel to a longitudinal direction of the support member.

It should be appreciated that the foregoing concepts, and additional concepts discussed below, may be arranged in any suitable combination, as the present disclosure is not limited in this respect.

The foregoing and other aspects, embodiments, and features of the present teachings can be more fully understood from the following description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features and advantages of the present invention will be apparent from the following non-limiting discussion of various illustrative embodiments and aspects thereof with reference to the accompanying drawings, in which like reference numerals refer to like elements throughout the different figures. For purposes of clarity, not every component may be labeled in every drawing. The drawings are provided for the purpose of illustration and explanation, and are not intended as a definition of the limits of the invention. In the drawings: Fig. 1 is an exploded view of one embodiment of an apparatus configured to rotate a solar collection device;

Fig. 2 is an assembled view of the embodiment shown in Fig. 1;

Fig. 3 shows a rotator assembly and a weight-bearing assembly according to one embodiment;

Figs. 4 through 6 shows three stages of rotation as the rotator assembly rotates counterclockwise;

Fig. 7 illustrates another embodiment of an apparatus configured to rotate a solar collection device;

Fig. 8 is a side view of the embodiment shown in Fig. 7;

Fig. 9 is a cross-sectional view take along line 9-9 in Fig. 8;

Fig. 10 is a top view of an embodiment of a brake apparatus in a first condition;

Fig. 11 shows the brake apparatus of Fig. 10 in a second condition;

Fig. 12 shows the brake apparatus of Fig. 10 in a third condition;

Fig. 13 is a side view of a solar energy collection device installation including a solar tracker according to one embodiment; and

Fig. 14 is a perspective view of the embodiment shown in Fig. 13.

DETAILED DESCRIPTION

Referring to Fig. 1, in some embodiments, a solar tracker device 1 has three functional portions. A rotator apparatus 10 provides rotary motion and may include an engagement member 12 by which a solar collection device may be attached. A weight- bearing apparatus 20 provides support to rotator apparatus 10 and its payload of one or more solar collection devices. The weight-bearing apparatus may permit an amount of lateral movement of the payload and/or a payload carrying member, for example through the use of linear slides and bearings. An engagement apparatus 30 attaches the prime mover to a mounting post or other support member (see Fig. 2). The support member may be mounted to a roof, inserted in the ground, or secured in any suitable manner to support the overall solar collection device assembly.

Referring to Fig. 2, solar tracker device 1 is shown attached to a support member, which in this embodiment includes a support post 40. A carrying member is positioned at the top of the support post in the form of a cap 42 in this embodiment. Cap 42 carries at payload such as solar energy collection device, and the cap is rotatable relative to support post 40. Engagement member 12 is shown engaged with cap 42 such that rotator 10 can rotate the cap.

Weight-bearing apparatus 20 supports rotator 10 on engagement apparatus 30 as shown in Fig. 2. By using weight-bearing apparatus 20, the load of the solar energy collection device (or other payload) is distributed over a larger area of rotator 10 as compared to being supported directly on engagement apparatus 30. However, in some embodiments rotator 10 may be supported directly by engagement apparatus 30.

Further, weight-bearing apparatus 20 (and thus rotator 10) may be movable relative to engagement apparatus 30, such that the cap 42 and rotator 10 can move when external forces (such as wind) are exerted on the payload. adjust to loads place.

The solar tracker device can be configured for retrofitting existing solar installations in some embodiments. For example, each of the various assemblies of the device shown in Fig. 1 can be separated in half such that each assembly can be reassembled around the support post by laterally engaging the separated pieces. In this manner, the payload, such as a solar energy collection device, does not have to be removed from the carrying member (e.g., a cap) to permit the device to be placed over the top of the support post. Instead, the device can be attached to the support post from the sides of the support post.

In some embodiments, the rotator is configured such that the support post is held at a position that is offset from the center of a rotating disk or other rotating mechanism. By providing an eccentrically oriented drive system, many of the components of the solar tracker may be positioned away from the solar collection device, such as a solar panel. This arrangement may allow an increased range of motion of the solar panel during adjustment to the elevation angle of the solar panel.

Rotator

In the embodiment shown in Figs. 1-3, rotator 10 include a sprocket 44 which is configured to be driven by a chain 46, which in turn is driven by a drive sprocket 48. An electric motor 43 drives drive sprocket 48 using one or more speed reduction gears 49. Other rotator assemblies may be used, for example a gear-based rotator assembly or a cable-based rotator assembly may be used in some embodiments.

Figs. 4-6 show three rotation orientation of rotator assembly 10 relative to weight-bearing assembly 20. An opening 18 is configured to engage with cap 42 or other carrying member. Opening 18 is offset from the center of sprocket 44 such that the axis of rotation 19 of the carrying member (the center of opening 18 in this embodiment) is offset from an imaginary axis which passes through a center of sprocket and is parallel to the axis of rotation.

By offsetting opening 18 from the center of sprocket 44, a lesser portion of the sprocket extends laterally from the post as compared to a centrally-located opening. This reduced extension allows a solar panel to tilt further toward a vertical arrangement before the sprocket interferes with the solar panel.

Sprocket 44 is equipped with a grooved track that is concentric with the pitch diameter of the sprocket. The grooved track guides the drive sprocket along an eccentric path created by the rotation of sprocket 44 about support post 40. Sprocket 44 uses the grooved track to maintain the orientation of the drive sprocket in relation to the center of the pitch diameter of sprocket 44. The path and geometry of the grooved track on sprocket 44 cause the drive sprocket to remain on the same geometric plane as sprocket 44 and provide a mechanical reaction to tension in the chain. Sprocket 44 maintains its vertical position through the use of engagement apparatus 12 which engages support post 40. The engagement apparatus allows sprocket 44 an amount of lateral deviation so as to allow opening 18 to apply external lateral loads directly to the support post.

Weight-bearing Apparatus

Weight-bearing apparatus 20 may include a lifting mechanism such that a weight- bearing surface 52 is upwardly movable into contact with sprocket 44. When lifted a sufficient distance, weight-bearing apparatus 20 lifts sprocket 44 and cap 42 off of support post 40, or at least lessens the load of the cap payload on the top of the support post. With the load reduced, sprocket 44 can rotate cap 42 and its payload more freely.

To lift weight-bearing surface 52, a first lifting camshaft 53 has a cam lobe 55 supported on a top surface 51 of engagement apparatus 20. When camshaft 53 is rotated 180 degrees, the cam lobe lifts the weight-bearing apparatus 20 away from top surface 51. As a result, the weight of the payload is transferred either partially or fully to the weight-bearing apparatus 20. A second lifting camshaft 57 also may be used so that the weight-bearing apparatus 20 remains oriented substantially horizontally after lifting. First and second lifting camshafts may be actuable simultaneously or individually.

Weight-bearing apparatus 20 includes sliding shafts 54, 56 which move along rollers 66, 68 such that weight-bearing surface 52 can move, typically in a horizontal plane that is normal to a longitudinal direction of support post 40. Shafts perpendicular to shafts 54, 56 may be included such that weight-bearing surface 52 can move two dimensionally.

Other arrangements for permitting lateral or other movement of rotator 10 may be used in some embodiments. For example, dampened movement parallel to the longitudinal direction of support post 40 may be provided in addition to, or instead of, the sliding movements provided perpendicular to support post 40. In some embodiments, the permitted movements of rotator 10 relative to support post 40 may be within a plane that intersects with the longitudinal direction of support post 40, but is not perpendicular to the longitudinal direction.

Engagement Apparatus

Engagement apparatus 30 includes a clamp 60 in the embodiment shown in Figs.

1-2. Clamp 60 is configured to be closed around support post 40 using an actuating screw 62 to move a horizontal link 64 and actuate levers 12 (one on each side). Actuation of the levers upwardly pulls the two sides of clamp 60 toward one another to engage with support post 40.

Of course other suitable arrangements for a clamp or other engagement member may be used in various embodiments, and this aspect is not intended to be limiting unless specifically recited in the claims. Exclusive Support

In some embodiments, all of the support of the cap by the support post may be through the solar tracker device. With such an arrangement, the cap may be rotatable without any friction on the support post. Further, by separating the direct support of the cap by the support post, and instead running the support via the solar tracker, an installed static solar collection device assembly may be retrofitted to include a solar tracker. For example, in some embodiments, the engagement assembly 30 is attached to a support post, and the rotator assembly 10 is attached to the cap, and the cap may be physically separated from the support post.

The solar tracker device may provide partial support in some embodiments. For example, the cap may be in contact with the support post, and the solar tracker device supports a portion of the weight of the payload. In this manner, the cap and payload may adequately supported such that there is limited friction between the cap and the post, and rotation is possible.

External Forces

Unusually strong external forces on the solar collection devices, such as a wind storm, can introduces stresses in the solar tracker system. The system may be configured such that a first reaction to such external forces is to allow the drive line to be backward driven, where the motor and all power transmission components are permitted to move in reverse in response to an applied external force. The drive and associated apparatus do not necessarily spin freely in such conditions, but instead apply a limited resistance in order for the motion to be controlled.

In the event that the range of motion for the rotator 10 has been reached and external forces are at a point where the solar devices may yield, an integrated shear pin 70 fails in a controlled manner and the clamp force will limit the rotational acceleration of the solar collection devices and associated apparatus.

Multiple Sprocket Embodiment

According to some embodiments, a multiple sprocket rotator assembly may be used. As shown in Fig. 7, a two sprocket rotator assembly 11 includes an upper sprocket 45 and a lower sprocket 47. A two sprocket configuration can provide greater torque than a single sprocket configuration, and can increase the amount of torque received from external forces such as wind.

The presence of two (or more) openings in the sprockets which are concentric and separated by a distance provides a more robust support structure for the support cap. As shown in Fig. 7, the openings may be offset from a center of the sprocket in a manner similar to the embodiment shown in Figs. 1-3.

The rotator apparatus used in the embodiment that is illustrated in Figs. 7-9 includes set screws 90 to attach the rotator to cap 42. Disk couplings 92 join the two sprockets and provide threaded holes through which the set screws can be driven into cap 42. A locknut 94 may be provided at the top of the threaded hole. Engagement apparatus 30 includes a pipe clamp 96.

In the cross-sectional side view of Fig. 9, a small clearance between support post 40 and cap 42 can be seen. This clearance allows cap 42 to move laterally relative to support post 40, but after moving a defined lateral distance, the cap contacts the post, and the support post absorbs forces placed on the cap.

Split Piece Design

In some embodiments, device 1 may be assembled around an existing support post such that a payload already supported on the post does not require removal for installation of device 1. For example, each of rotator apparatus 10, weight-bearing apparatus 20, and engagement apparatus 30 may have two or more separable portions which can be placed around post 40 or other support member and connected. In some embodiments, the separable portions are completely separable from each other, while in other embodiments, the separable portions may be pivotally connected to each other so that on side of the apparatus can be opened, placed around support post 40, and connected back together.

Brake

The apparatus includes a mechanical brake arranged to restrict motion upon detection of an unsafe condition in some embodiments. Examples of an unsafe condition include insufficient or irregular chain tension. Fig. 10 illustrates a first condition where a stationary brake pad 204 and an actuating brake pad 206 permit the brake drum to move freely. A trigger arm 222 rests on a trigger arm rest 208, and maintains resistance to a brake preload force originating in one or more brake actuating springs 210. Sprockets 218 and 220 apply force to a chain 212 by way of preloaded springs 214 and 216.

Fig. 11 illustrates a second condition where chain 212 yields to the load applied by sprockets 218 and 220 which are forced toward the trigger arm 222 by springs 214 and 216, or other biasing elements. Push rods 224 and 226 move in unison with sprockets 218 and 220 until contact is made with trigger arm 222. Trigger arm 222 reacts by moving away from trigger arm rest 208 until the potential energy stored in the actuating springs 210 are released. Brake pad 204 actuates and applies pressure to brake drum 202, thereby preventing movement of the brake drum. In this condition, examples of unsafe conditions include a broken chain or an elongated chain resulting from wear.

Fig. 12 illustrates a third condition where excessive torque is applied to one or more driven sprockets. The chain reacts by becoming tight on one side of the chain path and loose on the other. In this illustration, sprocket 220 is driven away from trigger arm 222 and allows slack to accumulate on the opposite side of the chain path causing sprocket 218 to move toward trigger arm 222. Push rod 226 comes in contact with trigger arm 222 causing it to move away from trigger arm rest 208 until the potential energy stored in actuating springs 210 are released. The actuating brake pad actuates and applies pressure to the brake drum 202 preventing movement of the brake drum.

Solar Energy Collection Installation

Figs. 13 and 14 show a solar panel 80 mounted to cap 42 with a solar tracker device 1 clamped to support post 40 and engaged with cap 42. As discussed above, a distance D between solar panel 80 and tracker device 1 is increased by having cap 42 offset from the center of sprocket 45. With such a configuration, solar panel 80 can be tilted closer to vertical before interference with tracker device 1 becomes problematic. While the embodiments disclosed herein have been described in association with solar collection devices, other payloads may be rotated and/or supported by

embodiments disclosed herein. For example, a wind turbine or other payload may be used with embodiments disclosed herein. While the present teachings have been described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art. Accordingly, the foregoing description and drawings are by way of example only.

What is claimed is:

Claims

1. An apparatus for positioning a solar energy collection device, the apparatus comprising:

a first rotator to rotate a solar energy collection device, the first rotator having an opening to receive a carrying member which carries the solar energy collection device, the first rotator further comprising an engagement member to engage the carrying member;

wherein when the engagement member engages the carrying member, the carrying member is offset from a center of the first rotator.

2. The apparatus as in claim 1, wherein the opening is offset from the center of the first rotator.

3. The apparatus as in claim 2, wherein the first rotator comprises a first rotating disk, and further comprising a second rotating disk positioned above and

concentrically with the first rotating disk, the second rotating disk having an opening which is offset from the center of the second rotating disk.

4. The apparatus as in claim 1, wherein the first rotator comprises a first sprocket.

5. The apparatus as in claim 4, further comprising a second sprocket and a chain, wherein the second sprocket is a drive sprocket configured to drive the first sprocket with the chain.

6. The apparatus as in claim 1, further comprising a weight bearing surface to support the rotator.

7. The apparatus as in claim 6, further comprising an actuator configured to lift the weight bearing surface from a start position to a support position so as to support the rotator.

8. The apparatus of claim 1, further comprising a clamp configured to attach to a support member which supports the solar energy collection device, wherein with the clamp attached to the support member and the engagement member attached to the carrying member, the apparatus permits movement of the carrying member relative to the support member.

9. An apparatus comprising:

a first rotator to rotate a solar energy collection device, the first rotator being configured to engage with a rotatable carrying member which carries the solar energy collection device, the carrying member having an axis of rotation; wherein

with the first rotator engaged with the carrying member, the axis of rotation of the carrying member is offset from an imaginary axis which passes through a center of the rotator and is parallel to the axis of rotation.

10. The apparatus as in claim 9, wherein the first rotator comprises a rotating disk which includes an opening to receive the carrying member, the opening being offset from the imaginary axis which passes through the center of the rotating disk.

11. The apparatus as in claim 10, wherein the rotating disk comprises a sprocket.

12. The apparatus as in claim 9, wherein the first rotator comprises a rotating disk which includes an opening to receive the carrying member, and further comprises an engagement member to engage the carrying member, wherein when the engagement member engages the carrying member, the carrying member is offset from the imaginary axis which passes through a center of the rotating disk.

13. The apparatus as in claim 9, further comprising the solar energy collection device and the carrying member, the rotator being engaged with the carrying member.

14. The apparatus as in claim 9, wherein the rotator comprises two portions which are at least partially separable from one another to permit the two portions to be placed around the carrying member and connected to one another to form the rotator.

15. An apparatus for positioning a solar energy collection device, the apparatus comprising:

a first engagement member to attach the apparatus to a support member such that the support member supports the apparatus; and

a rotator supported by the first engagement member, the rotator including a

second engagement member to attach the apparatus to a carrying member, the carrying member carrying the solar energy collection device and being rotatable relative to the support member to rotate the solar energy collection device relative to the support post when the first engagement member is attached to the support member and the second engagement member is attached to the carrying member; wherein

with the first engagement member attached to the support member and the second engagement member is attached to the carrying member, the apparatus permits movement of the carrying member relative to the support member.

16. An apparatus as in claim 15, wherein with the first engagement member attached to the support member and the second engagement member is attached to the carrying member, the apparatus permits movement of the carrying member relative to the support member in a direction which is not parallel to a longitudinal direction of the support member.

17. An apparatus as in claim 16, wherein with the first engagement member attached to the support member and the second engagement member is attached to the carrying member, the apparatus permits movement of the carrying member relative to the support member in a direction perpendicular to a longitudinal direction of the support member.

18. An apparatus as in claim 16, wherein the apparatus is configured such that the carrying member contacts the support member after moving a defined distance relative to the support member in the direction which is not parallel to a longitudinal direction of the support member

19. An apparatus as in claim 16, wherein with the first engagement member attached to the support member and the second engagement member is attached to the carrying member, the apparatus permits movement of the carrying member relative to the support member in a direction which is parallel to a longitudinal direction of the support member.

20. An apparatus as in claim 15, wherein with the first engagement member attached to the support member and the second engagement member is attached to the carrying member, the apparatus permits movement of the carrying member relative to the support member in a direction which is parallel to a longitudinal direction of the support member.

21. An apparatus as in claim 15, wherein with the first engagement member attached to the support member and the second engagement member is attached to the carrying member, the solar energy collection device is supported by the support member exclusively through the apparatus.

22. An apparatus as in claim 15, wherein the carrying member comprises a hollow member positioned over a longitudinal portion of the support member, and the hollow member has an internal diameter that is greater than an external diameter of the support member along the longitudinal portion.

23. An apparatus as in claim 15, wherein the carrying member comprises a hollow member positioned over a longitudinal portion of the support member, and the hollow member has an internal cavity with a minimum distance across a cross-section normal to a length of the cavity which is greater than a maximum external distance across a cross-section of the support member along the longitudinal portion of the support member.

24. A rotatable solar collection device support assembly comprising:

a support member;

a carrying member supported by the support member, the carrying member configured to carry a solar collection device; a rotator configured to rotate the carrying member relative to the support member; wherein

the carrying member is movable relative to the support member in a direction which is not parallel to a longitudinal direction of the support member.

25. The rotatable solar collection device support assembly as in claim 24, wherein the rotator is connected to an engagement member that is engaged with the support member.

26. The rotatable solar collection device support assembly as in claim 25, further comprising a weight bearing section which supports the rotator and is connected to the engagement member that is engaged with the support member.

27. The rotatable solar collection device support assembly as in claim 26, wherein the carrying member on the support member is supported exclusively through the rotator, the weight bearing surface and the engagement member.

28. An apparatus as in claim 24, further comprising a solar collection device carried by the carrying member.