Bearing adapter for single-axis trackers

Abstract

According to the present invention, a bearing adapter for use with a truss base supporting a mechanically balanced single-axis tracker is provided. The bearing adapter combines with the free ends of a pair of adjacent truss legs to form a rigid A-frame shaped base structure. A bearing is formed on the upper part of the bearing adapter so that a torque tube is suspended on a pin within the bearing and can swing through an arc bounded by the bearing adapter. The bearing may have a catenoid shape to compensate for misalignment in multiple directions.

Description

Technology Field

[0001] The present invention claims priority to U.S. Provisional Application No. 62 / 875,924 filed July 18, 2019, with the title "Bearing adapters for single-ais trackers supported by truss foundations" and U.S. Provisional Application No. 62 / 814,789 filed March 6, 2019, with the title "Bearing housing assemblies and related systems and methods for A-frame foundation supporting mechanically balanced single-axis trackers", the disclosures of which are incorporated herein by reference in their entirety. Background Technology

[0002] Solar energy is one of Earth's greatest potential energy sources. Above the atmosphere, solar irradiance per unit area is 1.361 kilowatts per square meter. At sea level, the available energy density drops to 250 watts per square meter. Approximating the Earth using a two-dimensional model, 250 watts / m² * π * 6,371,000 m² generates approximately 32,000 terawatts of energy continuously striking the Earth's surface. Assuming the Sun continues to burn and emit photons for over a billion years, the survival of human life ultimately depends on utilizing this inherently infinite, clean energy source.

[0003] To date, the primary obstacle to large-scale solar adoption has been cost. Unlike other energy sources, solar energy costs are paid upfront, while operating costs are relatively low. Fossil fuel-based energy sources require upfront costs as well as charges resulting from fuel consumption. Unfortunately, not all ongoing costs are reflected in the price of energy generated from fossil fuel sources. In the absence of a carbon tax, these "dirty" energy sources incur significant external costs due to CO2 emissions that are not yet reflected in consumer costs. Furthermore, eroded public corporations and fossil fuel producers have effectively lobbied to obstruct solar power generation even in states with the greatest potential.

[0004] Despite these headwinds, the cost of solar power has now fallen low enough to be equivalent to or cheaper than coal, oil, and natural gas, even when combined with energy storage. In the context of the power market, the relative cost difference between competing resources is typically quantified in kilowatt-hours (kWh) in terms of cost per unit of energy. Large-scale solar arrays, known as "public-scale" arrays, can have generating capacities ranging from tens to hundreds of megawatts, which is equivalent in scale to small-scale coal and natural gas power plants. These arrays typically produce electricity supplied to the grid and sell it at a wholesale price of a few cents per kWh. The development of public-scale solar projects is financed through so-called Power Purchase Agreements (PPAs). Through a PPA, the off-taker (e.g., public corporations, grid operators, etc.) agrees to purchase all electricity generated by the system at a fixed rate for the array's operational life (e.g., 30 years). This allows banks or other investors to accurately assess projected future trends and finance the construction of the array by providing loans.

[0005] Construction-scale solar power plants are primarily composed of fixed-tilt ground-mounted arrays or single-axis trackers. Fixed-tilt arrays are arranged in rows of panels oriented east-west, tilted to the south at an angle specified according to the latitude of the array site, with the tilt angle becoming steeper as it moves further away from the equator. In contrast, single-axis trackers are installed in rows of panels oriented north-south, with solar panels attached to a rotating axis called a torque tube that moves the panels from east to west throughout the day, following the sun's movement across the sky. For the purposes of this disclosure, both fixed-tilt and single-axis trackers are collectively referred to as axial solar arrays.

[0006] Most single-axis tracer manufacturers use one of two possible configurations to attach the torque tube to the base of a monopile. Most commonly, a torque tube support element (e.g., bearing housing, bearing housing support, etc.) is attached to the top, flange, or side of a standard row of H-piles. The bearing surrounds the torque tube, and the tube rotates internally like an axle within a wheel bearing. Monopiles typically have holes or slots formed at one end of each flange or web, allowing the torque tube support element to be easily attached and adjusted vertically, and in some cases, the torque tube to be aligned horizontally with other piles and bearing housings in the row. One commercially available system using this bottom-up configuration is the DuraTrack HZ single-axis tracer from ARRAY TECHNOLOGIES, INC., Albuquerque, NJ, USA. In the DuraTrack system, the torque tube rotates directly around its axis within a bearing located on top of the H-pile. Many other tracer manufacturers also use this same bottom-up design.

[0007] Although less commonly used, at least one tracker manufacturer has successfully commercialized a tracker with a top-down configuration in which the torque tube is suspended by a bracket of hinge pins, allowing the entire tube to swing like a pendulum rather than rotate around its own axis. In this system, the drive motor is offset from the center of the torque tube to align with the system's center of rotation, which is the bearing pin. Commercially known as the NX Horizon single-axis tracker from NEXTRACKER INC. in Fremont, California, this tracker claims to be mechanically balanced, meaning the amount of torque required to move the torque tube is the same at all panel angles. While top-down systems require more torque to resist gravity as the module's angle relative to the ground becomes steeper, in a balanced system, the required torque remains constant and overturning moments are reduced. However, because the torque tube is suspended and swings through an arc, an east-west gap is required in the structure holding the tube. This is a constraint that is not present in top-down systems. To accommodate this, the NEXTracker attaches a pair of right-angle brackets to the outer surface of each flange of the H-pile to provide a horizontal mounting platform wider than that provided by the H-pile alone. Then, an inverted U-shaped bearing housing assembly is mounted on this horizontal platform, and a torque tube is suspended from a bearing pin mounted on a bearing at the center of the inverted U.

[0008] Excluding land acquisition costs, the total project cost for a construction-scale array may include site preparation (road construction, leveling, grid and water connections, etc.), foundations, trackers or fixed-slope hardware, solar panels, inverters, and electrical connections (conduit, wiring, trenching, grid interfaces, etc.). While most of these costs have decreased over the past few years due to continuous innovation and economies of scale, one area that has been largely overlooked is the foundation. Foundations provide a uniform structural interface that connects the system to the ground. When installing conventional single-axis trackers, after the site is prepared, vertical monopiles are typically driven into the ground at regular intervals specified by the tracker manufacturer and site planner; tracker system components are subsequently attached to the heads of these piles. In most cases, the piles used to support the tracker are H-shaped profiles, but they can also be C-shaped or even box-shaped. In conventional large-scale single-axis tracker arrays, foundation procurement and construction can account for up to 5–10% of the total system cost. Despite accounting for a relatively small share of the total cost, the savings in steel and labor costs associated with foundations will amount to a significant sum compared to a portfolio of large-scale solar projects. In addition, since tracker development transactions are often fixed more than a year before installation costs actually occur, the realized post-transaction savings will be added to the profits already considered in the calculations supporting the construction of the project.

[0009] One reason monopiles continue to dominate the single-axis tracker foundation market is their simplicity. While it is relatively easy to drive monopiles into the ground in a straight line with existing technology, the design itself is wasteful. The physics of monopiles dictates that they must be large because a single structural member does not withstand bending forces well. When used to support single-axis trackers, the greatest force applied to the foundation is not the weight of the components, but the combined lateral force of the wind striking the solar panels. This lateral force is transmitted to the monopile foundation as a bending moment. The magnitude of this force is much greater than the static load caused by the weight of the panels and tracker components. It acts like a lever arm attempting to bend the pile, and the longer the lever arm, the greater the force. Many tracker companies specify a minimum foundation height of at least 40 inches. Therefore, in the case of single-axis trackers, monopile foundations must be large and driven deep into the ground to withstand lateral loads.

[0010] One proposed alternative to monopile foundations is to use a pair of moderately inclined legs to form an A-frame or truss-type foundation. Truss foundations have the potential to increase construction-scale solar installations by reducing costs compared to monopiles. One reason for this is that truss foundations convert lateral loads applied to trackers into axial forces—specifically tension and compression—of the truss legs rather than bending forces. Since single structural members have weaker bending resistance compared to their ability to resist axial forces, heavier and thicker steel must be used when supporting single-axis trackers with monopiles against truss foundations. Additionally, because the truss supports lateral loads primarily through the tension and compression of the legs, the legs do not need to be driven as deep as an equivalent monopile. This not only saves steel but also reduces the likelihood of encountering underground rock. Since the monopile mitigation process to overcome rock rejection costs nearly ten times more than simply driving the monopile into the ground, reducing rejection can save on project installation costs.

[0011] Finally, for some tracers, tracer-foundation integration has the potential to further reduce costs compared to H-piles. Since the vertex hardware connecting adjacent truss legs can form an A-frame structure to constitute part of the tracer, the total number of parts can be reduced. In particular, by joining adjacent truss legs with the same components that provide bearings to the tracer's rotating members (i.e., torque tubes, bearing pins, etc.), the combined tracer and foundation can be manufactured and constructed more affordably. The problem to be solved

[0012] To this end, the objective of the various embodiments of the present disclosure is to provide a bearing adapter that optimizes the amount of steel and embedment depth required for a given diameter by providing a truss or A-frame foundation for single-axis tracer application. means of solving the problem

[0013] Included in the contents of the present invention. Effects of the invention

[0014] Included in the contents of the present invention. Brief explanation of the drawing

[0015] FIG. 1a illustrates a portion of a single-axis tracker according to various embodiments of the present invention. FIG. 1b illustrates the components of a truss leg that can be used in various embodiments of the present invention. FIG. 2 illustrates a bearing adapter according to various embodiments of the present invention. FIGS. 3a to 3c illustrate different bearing adapters that can be used with a truss foundation according to various embodiments of the present invention. FIG. 4a illustrates another bearing adapter that can be used with a truss foundation according to another embodiment of the present invention. FIGS. 4B and FIGS. 4C illustrate a bearing adapter having a catenoid-shaped bearing opening. FIG. 5 illustrates a cardioid-shaped bearing adapter and a truss foundation according to various embodiments of the present invention. FIGS. 6a to 6c illustrate various drawings of the cardioid-shaped bearing adapter of FIG. 5. FIG. 7 shows the bearing adapter of FIG. 5 superimposed on a bearing housing assembly of the prior art. FIG. 8 illustrates different bearing adapters and truss foundations according to various embodiments of the present invention. FIGS. 9a to 9c illustrate different drawings of the bearing adapter of FIG. 8. FIG. 10 shows the bearing adapter of FIG. 8 superimposed on a bearing housing assembly of the prior art. Specific details for implementing the invention

[0016] The following description is intended to convey a thorough understanding of the described embodiments by providing details and a number of specific embodiments, including an A-frame base used to support a single-axis solar tracker. However, it should be understood that the invention is not limited to these specific exemplary embodiments and details. It is further understood that a person skilled in the art can understand the use of the invention for its intended purpose in light of known systems and methods.

[0017] Referring to FIG. 1a, this drawing illustrates a portion of a single-axis tracker system (100) supported by an A-frame base (10) according to various exemplary embodiments of the present invention. The illustrated portion (100) includes a partial A-frame base (10) attached to a bearing adapter (15) that supports a section of a suspended torque tube (20). A structure that performs the functions of an adapter and a tracker bearing assembly is generally referred to as a "bearing adapter." That is, it structurally connects the free ground ends of adjacent truss legs and provides a bearing that accommodates a rotating member to allow the torque tube to move. In the example of FIG. 1, the rotating member is a bearing pin to which the torque tube is rotatably connected. In other embodiments, the rotating member may be the torque tube itself. In such embodiments, the bearing opening would be much larger to accommodate the torque tube, and since the torque tube rotates in place rather than swinging like a pendulum against the bearing, the bearing adapter does not need to be wide or large.

[0018] The legs of the A-frame have been cut off to focus on the elements that are the subject of this disclosure. In this example, the torque tube (20) is suspended from a hinge pin (16) passing through a bearing adapter (15) hinge bracket (18). Several PV modules (110) are attached to sections of the torque tube (20) via C-clamp brackets connecting the frames of each module to the torque tube. For convenience of description, only a portion of the array is shown. In an actual installation, there are several bases spaced apart along the torque tube (20) and at least one motor or drive linkage for moving the bearing adapter and the rotation assembly so that the panels remain in the sun (i.e., perpendicular to the sun) all day long. The tracker shown in FIG. 1a is a top-down system, such as the one manufactured and sold by NEXTRACKER INC in Fremont, California, as discussed above, in which the torque tube is not fixed to a circular bearing seated on the base but is suspended from a pin on the tube. In this example, the unique bearing adapter not only provides a bearing that suspends the torque tube and limits the east-west swing range of the tube, but also completes the A-frame by connecting the free ends of each truss leg to each other to form a truss base of a rigid A-frame shape, as described in more detail herein. In various embodiments, this connection is achieved by inserting a portion of the bearing adapter into each leg and crimping it into place.

[0019] In this example, the bearing adapter (15) has a cardioid shape. The cardioid shape is characterized by a pair of symmetrical S-shaped arms that follow an inverse S-shaped path and meet at the center of the cusp. The ends of each S-shaped arm are spaced apart and angled to match the angle and distance between adjacent legs of the A-frame base. It should be understood that other shapes may also be possible.

[0020] FIG. 1b illustrates the components of a truss foundation system (10). These include a pair of screw anchors (11), a pair of upper legs (13), and a drive coupler (12) located at the top of the screw anchors. The coupler (12) is used to drive the screw anchors to the supporting ground and to connect the upper legs to the screw anchors. In some embodiments, this coupler or collar may be welded to the head of each base pile. In other embodiments, it may be fixed in the field before or after the piles are driven. The coupler may be formed with teeth to be paired with the drive head of a rotary drive machine to transmit torque to the piles during driving. When a pair of adjacent base piles are driven to the desired foundation position, the upper or extension piles are coupled to each base pile. In various embodiments, this is achieved by inserting the ends of each upper pile onto the coupler or collar until they are seated on the protrusions of the coupler. The alternating slopes of the coupler allow the upper piles to be axially aligned so that both are in the same plane and point toward the desired working point. Once proper alignment is achieved, a crimping tool can be used to secure the upper file to the base file, and a portion of the upper file can be crimped over the channel formed in the coupler to preserve the orientation of the upper file. Then, a bearing housing assembly is attached to the free end of the upper file to complete the A-frame, as discussed in more detail below.

[0021] As illustrated, the screw anchor (11) includes an external thread at its lower end. In various embodiments, such a screw anchor is driven into the ground by a rotary driver until the driven end is on or near the inclined surface. In various embodiments, adjacent legs (10) are driven in reverse relative to each other. For example, the piles may be driven in a direction of ±60 degrees toward each other. In other embodiments, the piles may be driven in reverse relative to each other over a range of 55 to 72.5 degrees. In various embodiments, an articulated coupler may be attached to the head of each base pile. Although an articulated crimp collar is illustrated in the drawings, it should be understood that other techniques may be used to attach the upper pile to each base pile without departing from the spirit or scope of the invention.

[0022] FIG. 2 illustrates a front view of the bearing adapter (30) of FIG. 1 according to various embodiments of the present invention. The bearing adapter (30) comprises a generally cardioid shaped member formed by a central cusp (32) and a symmetrical inverse S-shaped arm (34) protruding far toward the cusp (32). In various embodiments, the adapter (30) may be formed by casting steel. In other embodiments, the assembly may be cold-formed, for example, through a stamping process. In various embodiments, a bearing, such as a bearing (33), is located on or near the cusp (32) along the vertical midline of the assembly. In this context, "vertical" refers to the orientation of the assembly when the upper cusp and the end of each S-shaped arm at the lower are installed. In this example, the bearing (32) is composed of a tubular recess that passes completely through the main body of the adapter (30). Each S-shaped arm (34) extends away from the cusp (32), then bends back toward the cusp, and then bends to match the spacing and angle of the A-frame leg (10). As discussed above, the ends of the arms (34) may be bent downward away from the centerline at an angle ranging from 17.5 to 35 degrees to match the angle of the corresponding truss leg (10) oriented at an angle ranging from 55 to 72.5 degrees.

[0023] In various embodiments, and as illustrated herein, the S-shaped arm (34) is symmetrical, but its end features are not symmetrical. This is because if the ends of both arms were of equal length, it might be impossible to insert the ends into their respective inclined upper legs (13) simultaneously before they are crimped into the screw anchor (11). Therefore, in the example of FIG. 2, one arm is terminated in a welded crimp sleeve (35) that follows the same axis but extends several inches beyond the end of the arm (34). In various embodiments, and as illustrated, the welded crimp sleeve (34) is welded to the end of the arm and includes a crimp joint adjacent to the end. The crimp joint is characterized by a narrower diameter section that allows space for the upper pile to be crimped upward. The end (36) of the opposing arm includes a sleeve that is relatively shorter and has a twist-lock feature. In this case, a female feature is illustrated, but in other embodiments, a male feature may be used, or even a combination of male and female features may be used. The separated twist-lock sleeve (37) is used to connect and extend the relatively short twist-lock sleeve (36) to the upper leg (13) to interface the bearing adapter (30) to the truss foundation (10).

[0024] The installation of the components illustrated in FIGS. 1a / 1b and FIGS. 2 is achieved as follows. The screw anchor (11) and the upper leg (13) are installed in the manner described above with respect to FIGS. 1b. Then, a relatively long welded crimp sleeve (35) of the bearing adapter (30) is inserted into the free end of one of the upper legs. In various embodiments, the crimp sleeve (35) will have an outer diameter slightly smaller than the inner diameter of the upper leg (13) to enable a smooth fit with minimal slope. The crimp sleeve (35) may have a uniform diameter so that the assembly can rotate 360 ​​degrees within the upper leg (13) to rotate without interfering with the adapter (30) while the other side is being constructed.

[0025] Next, the separated twist-lock crimp sleeve (37) is inserted into the free end of the other upper leg so that the crimp joint end is facing downward. In various embodiments, a bump stop (38) is formed in the sleeve (37) to prevent it from disappearing downward into the upper leg (13). Once inserted, the adapter (30) is rotated around so that the relatively short twist-lock sleeve (36) points toward the separated sleeve (37) into which it is inserted. Then, the sleeve (37) slides axially upward within the leg until it engages with the relatively short twist-lock sleeve (36). Once the male and female features are properly oriented, the separated sleeve (37) will slide toward the female (34). Once fully inserted, the separated sleeve (37) is then rotated clockwise or counterclockwise until the male features are firmly secured at their respective stops. At this point, fine adjustments between the adapter (30) and the upper leg (13) can be made by lifting or lowering the bearing adapter (30) until the bearing (33) is aligned with the desired work point and / or another bearing in the same row. Installation is completed by crimping each upper leg (13) over the crimp joints formed in the separate and welded crimp sleeves (37 / 35), respectively. The crimp joints hold the assembly in the desired direction. Crimping can be performed with an electric handheld crimping device or an articulated crimper attached to a machine used to install base piles.

[0026] Referring to FIGS. 3a through 3c, these drawings illustrate a bearing adapter (40) according to various other embodiments of the present invention. As in the exemplary embodiment shown in FIG. 2, the adapter (40) also features a cardioid-shaped structure having a pair of symmetrical inverse S-shaped arms (44) that curve toward and away from a centrally located cusp (42) and a stip plate. An integral bearing (43) located below the cusp (42) is formed by an axial opening passing through the adapter (40). As discussed herein, the adapter (40) may be formed from one or more cast pieces by stamping or by some other process. In this embodiment, each S-shaped arm (44) is terminated at a crimp arm (45 / 46). The crimp arms (45 / 46) may be formed from the same casting as the adapter (40) or formed separately and welded after the assembly (40) is formed. In this example, one arm (46) is shown as a short crimp arm (45) and the other as a long crimp arm (45). The reason for having arms of different lengths is the same as discussed above in the context of FIG. 2, that is, to enable simultaneous fitment with the fixed upper leg (13). As shown in FIGS. 3a and 3b, the crimp arms (45 / 46) include a plurality of crimp features. In these figures, the crimp features consist of a plurality of alternating ribs and gaps as well as a flat surface that provides a gap so that the upper leg (13) can be sleeved toward the crimp arms. This embodiment also includes a separated crimp sleeve (47). As with the crimp sleeve (47) of the embodiment of FIG. 2, the crimp sleeve (47) includes a crimp joint adjacent to one end. Unlike the sleeve (37), there is no twist-lock feature, because the sleeve is fitted directly onto the short crimp arm (46) of the adapter (40) and crimped in place.

[0027] The system installation is similar to the adapter (30) of FIG. 2. After installing the screw anchor (11) and the upper leg (13), the installation of the bearing adapter (40) can begin. In this exemplary embodiment, the installation begins by inserting a long crimp arm (45) into the free end of one of the upper legs. In various embodiments, the outer diameter of the crimp arm (45) is made slightly smaller than the inner diameter of the upper leg (13) but so that the arm can easily enter without tilting too much. Once inside, the adapter (40) can be rotated unobstructed to allow access to the free end of the adjacent upper leg. One end of the crimp sleeve (47), which includes a crimp joint, slides toward the free end of the upper leg until the bump stop (48) leg opens. Then, the adapter (40) is rotated again so that the shorter crimp arm (46) points toward the separated crimp sleeve (47). The sleeve (47) slides back up until it covers at least a portion of the short crimp arm (46). Then, the bearing adapter (40) is leveled and the bearing (43) is aligned with the height and east-west position of the desired work point. Once aligned, the upper leg (13) is crimped directly into the sleeve over the crimp joint area of ​​the crimp sleeve (47) and along the portion of the sleeve that overlaps with the short crimp arm (46). Finally, the other leg is crimped to engage with the long crimp arm (45), thereby maintaining the orientation of the bearing adapter and the work point of the truss base.

[0028] Now, referring to FIGS. 4a through 4c, these drawings illustrate the features of a bearing adapter that can be used with various embodiments of the present invention, in this case, the adapter (30) shown in FIG. 2. It should be understood that even though the bearing housing shown in FIG. 4a corresponds to that shown in FIG. 2, the adapter (40) of FIGS. 3a through 3c, or even other adapters, can be used with the various embodiments shown in FIGS. 4a through 4c. In fact, this feature can also be used with various other types of top-down or bottom-up style trackers. Starting with FIG. 4a, this drawing shows a front view of an exemplary bearing adapter (30). Like other adapters, it is substantially cardioid-shaped with a symmetrical S-shaped arm (34). A line AA bisecting the center of the adapter (30) passes through the cusp (32) and the bearing (33) below it. FIG. 4b shows an internal cross-sectional view taken along bisector AA, and FIG. 4c is an enlarged view of the bearing surface (33A) inside the adapter (30). As shown in FIG. 4b and 4c, the bearing (33) in the adapter (30) is an opening that passes completely through the adapter (30), providing a bearing surface for the bearing pin to rotate inside. The bearing surfaces (33A) together form a catenoid-shaped opening. In the cross-sectional view, this is generally shown as a pair of convex surfaces, indicating that the diameter is narrowest at the center and increases toward the bearing openings on both sides. Although this surface is shown as a catenoid shape, in some embodiments, the surface may be formed as a ramp rising from one opening toward the central apex. When the bearing pin is inserted into the bearing (33), the convexly curved bearing surface (33A) allows the pin to articulate a few degrees in any direction within the bearing. In various embodiments, this can relieve stress and deformation on the torque tube, torque tube support bracket, and even the foundation due to misalignment from bearing adapter to bearing adapter.Bearing surfaces of uniform diameter require that each bearing housing be oriented substantially the same. This may be difficult to achieve in real-world situations where anchors are driven by heavy equipment in the soil across terrains of varying grades and moisture content. The catenoid-shaped bearing opening according to the present embodiment extends the functional life of the tracer system by allowing the bearing pin to rotate without bending the torque tube to move the bearing or base into alignment or to compensate for misalignment. The dashed line in FIG. 4b indicates different possible orientations of the bearing pin within the catenoid-shaped bearing.

[0029] Now, referring to FIG. 5, this drawing illustrates an exemplary truss foundation and bearing adapter system (200) according to various embodiments of the present invention. As in other embodiments, the truss foundation consists of a pair of truss legs (10) extending below and above the ground. Each leg (10) consists of a screw anchor (11) driven almost entirely to the ground and an upper leg (13) that substantially extends the axis of the corresponding screw anchor. A coupler (12) attached to or embedded in the head of the screw anchor serves as a platform to which the upper leg is attached. The upper leg (13) can be joined to each screw anchor (11) using a crimp joint, pin, thread, or other suitable mechanical fastener. The upper leg (13) is terminated in an open tube. The bearing adapter (50) is a cardioid-shaped member at the top of the truss. It includes a pair of connecting parts (52) that are received by adjacent upper legs (13) and then the leg is crimped or otherwise secured to the bearing adapter (50). The adapter (50) includes a cardioid-shaped opening with a bearing (53) formed in the cur of the opening. In various embodiments, a bearing pin is received within the bearing (53) and one or more torque tube support brackets are attached to the bearing pin to suspend the torque tube.

[0030] In some embodiments, the bearings and connections may be positioned so that a line passing through the center of mass of each connection roughly intersects the bearing. The axis of rotation of the tracer (the bearing pin in this example) is then aligned with the apex or working point of the truss. This ensures that almost all lateral loads are transferred to the truss legs as axial forces while minimizing the range of bending moments. Since monopiles convert lateral loads into bending moments depending on the design, these considerations apply only to truss foundations. They are primarily large in size to resist such moments.

[0031] FIGS. 6a through 6c illustrate a front view, a side view, and a perspective view, respectively, of the bearing adapter (50) of FIG. 1. As illustrated, the adapter (50) has a main body (51) formed from a pair of substantially identical cardioid-shaped plates, labeled 51A / B in FIG. 2b, joined by a clinch or press joint. The clinch joint is formed by using a punch and die assembly to push a protrusion formed on one piece into a recess formed on the other piece, thereby inducing a slight underflow at the bottom to lock the two pieces together. The clinch joint is advantageous because it does not require heat, welding, or chemicals. However, it should be understood that the number of clinch joints illustrated herein is merely illustrative and should not be construed as limiting the invention. Additionally, methods other than clinching may be used, or the entire piece may be made by a single casting.

[0032] Next, after the main body (51) of the cardioid shape is formed, a pair of connecting parts (52) are attached along the bottom of the main body (51) so that the adapter can be joined to a pair of adjacent upper legs. When the pieces (51A, B) are joined, the connecting parts (52) can be bolted, welded, or otherwise attached at an appropriate angle to match the angle of the truss leg (10) and ensure that they point toward the bearing (53). This will minimize the range in which lateral loads are transferred as axial loads rather than bending moments.

[0033] FIG. 7 combines the drawing of the bearing adapter (50) shown in FIG. 5, 6a-c with the so-called bearing housing assembly used in conventional single-sided tracers when supported by a monopile foundation. The bearing housing assembly shown herein is an NX SERIES single-sided tracer manufactured and sold by NEXTRACKER, INC. of Fremont, California. In this superimposed drawing, it can be seen that the height and width of both the bearing housing assembly (BHA) and the bearing adapter (50) are substantially the same, and that both define at least a partially cardioid-shaped opening and have bearings in the same position. Although the NEXTRACKER BHA is designed to be saddled on a flat surface, the swing of the torque tube requires a clearance greater than that provided by a 6-inch wide H-pile (e.g., W6×9 or W6×12). Therefore, NEXTRACKER manufactures a right-angle bracket that provides a horizontal mounting surface for the BHA and transfers the load of the tracer to a vertical interface that can be attached to the opposite flange of the H-pile. They also widen the stance of the H-pile to accommodate cardioid-shaped openings. Finally, they increase the height of the bearing and provide some degree of vertical height adjustment to align with other BHAs in the same row.

[0034] In contrast, the truss foundation and bearing adapter according to various embodiments of the present invention allows the H-pile flange, right-angle bracket, and bearing assembly to be functionally combined into a single part, making the single tracker more cost-effective when supported by the truss foundation and bearing adapter for a monopile. The bearing adapter coupled to the truss leg does not require the base, right-angle bracket, H-pile flange, and the numerous Huck bolts or other fasteners used to connect these components together. This accomplishes all of this while maintaining dimensional compatibility with the remaining single tracker components (e.g., bearing pin, torque tube support bracket, torque tube, module bracket, etc.).

[0035] It should be understood that not all system components in a tracker array are exposed to the same forces. The outer rows, or the first few outer rows, may be made more rigid than the rows constituting the interior of the array because the inner rows are protected from wind to some extent by the outer rows. To this end, the tracker components and foundation components may differ between the outer and inner rows, as well as between those supporting the torque tubes and those supporting the drive motors and / or other driveline components. In various embodiments, the bearing adapters illustrated in FIGS. 3a, 4a, 5, and 6a-c are designed for the interior portion of the tracker array under standard loads, namely, the location where the tracker is installed, soil conditions, and prevailing weather, among other factors. The trusses and bearing adapters for the outer rows may have different configurations, as illustrated in subsequent embodiments.

[0036] Now, referring to FIGS. 8 and FIGS. 9a through 9c, these drawings illustrate other truss foundations and bearing adapters according to various embodiments of the present invention that may be more suitable for external rows and / or installations requiring greater force than the bearing adapters illustrated in relation to other embodiments. Starting with FIG. 8, this drawing illustrates truss foundations and bearing adapters according to various other embodiments of the present invention. The lower part of the truss foundation illustrated herein is substantially the same as in other embodiments. It consists of a pair of truss legs (10), each consisting of a driven screw (11) anchor coupled to an upper leg (13) via a coupler (12). One or more crimps, bolts, or other mechanical fasteners may secure each upper leg (13) to the corresponding coupler. Alternatively, the coupler (12) may be a separate casting or piece attached to the lower end of the upper leg, or a set of features stamped or otherwise formed on the upper end of the screw anchor.

[0037] The truss legs illustrated in these drawings are also joined by bearing adapters (60) that may be stronger than those illustrated in Fig. 1 in this example. The bearing adapters illustrated herein are formed by a pair of tubular S-shaped members (64) joined at one end by a straight bridge member (61) having a bearing (63) in the middle. The other end of each S-shaped member (64) terminates at a connection (65) that is received within the open end of each upper leg (13) in various embodiments. Additionally, as illustrated, a gusset plate (62), a brace, or other support material connects the S-shaped members (64) at the narrowest point to resist separation and twisting. In various embodiments, the bearing adapters (60) may be formed from a bent steel tube, an interconnected section of a steel tube, or a combination thereof, and, among other possibilities, may have a circular, square, or elliptical cross section.

[0038] FIGS. 9a through 9c are a front view, a cross-sectional view, and a perspective view, respectively, of the bearing adapter (60) shown in FIG. 8. FIG. 9b is a cross-sectional view along line AA of FIG. 9a. As shown in FIG. 9a, the bearing adapter (60) is composed of a pair of substantially identical but opposing S-shaped members (64), which start at a common bridge portion (61) in the middle of the adapter and end at each connecting portion (65). The bridge (61) includes a bearing (63), and in this example, the bearing (63) is welded to brackets on both sides of the bridge to pass completely through the adapter (60) and hangs slightly below the bridge. Alternatively, the bearing (63) may be embedded in the bridge (61). To provide additional strength, a gusset plate or support brace (62) is coupled with the inverse S-shaped member (64) at the narrowest point. As illustrated, the connecting portion (65) is configured to be fitted into each upper leg (13) so that the leg (13) can be crimped around the upper leg (13). In another embodiment, it should be understood that the upper leg (13) may be fitted into the connecting portion and a bolt, pin, or other suitable mechanical fastener may be used to join the connecting portion (65) to their respective upper leg (13).

[0039] FIG. 10 is a front view of the bearing adapter (60) shown in FIG. 8 and 9a-c superimposed with a bearing housing assembly of the prior art. The prior art BHA is a NEXTRACKER NX SERIES single-axis tracker designed to be attached to a single H-pile. It is formed from an inverted U-shaped steel tube section ending at one end of a set of supports that rest on each right-angle bracket attached to the vertical flange of the H-pile. As can be seen in the image of FIG. 10, the bearing of the prior art BHA and the bearing adapter (60) according to various embodiments of the present invention are superimposed, as in the bearing adapter shown in FIG. 7, and the height and width of these structures are substantially the same. The difference lies in the shape of the lower end of the bearing adapter, which can be combined with an angled truss leg rather than a conventional H-pile. This eliminates the need for Hcuk bolts or other fasteners used to connect them together while maintaining dimensional compatibility with the base, right-angle bracket, and upper flange of the H-pile, as well as the remaining single-axis tracer components (e.g., bearing pin, torque tube support bracket, torque tube, module bracket, etc.).

[0040] The scope of embodiments of the present invention is not limited by the specific embodiments described herein. In fact, various variations of embodiments of the present invention other than those described herein will be apparent to those skilled in the art from the foregoing specification and the accompanying drawings. Accordingly, such modifications are intended to fall within the scope of the following appended claims. Furthermore, while some embodiments of the present invention have been described herein in the context of specific implementations in specific environments for specific purposes, those skilled in the art will understand that the usefulness thereof is not limited thereto and that embodiments of the present invention may be advantageously implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be interpreted in the full spirit and technical concept of the embodiments of the present invention as disclosed herein.

Claims

Claim 1 A bearing adapter for a single-axis tracker comprising: a main body having a cardioid shape with a cusp in the center; a bearing opening formed through the cusp along the vertical centerline of the main body; and a pair of connecting parts extending downward and outward from both sides of the lower end of the main body and spaced apart from each other; wherein each connecting part is formed to be inserted and fixed inside the upper end of a pair of inclined truss legs, and the bearing opening is configured to rotatably receive a bearing pin so that the center axis of the bearing pin forms a rotation axis corresponding to the intersection point of the truss legs. Claim 2 In claim 1, the bearing adapter is formed such that the cardioid-shaped main body includes an inverted S-shaped arm symmetrical with respect to the cusp. Claim 3 In paragraph 2, the cardioid shape defines a first plane, and the bearing adapter is formed in an axial direction substantially orthogonal to the first plane. Claim 4 A bearing adapter according to claim 1, wherein a bearing pin is inserted into the bearing opening, and the bearing pin is coupled to a bracket supporting a torque tube to form a rotation axis of the torque tube. Claim 5 A bearing adapter according to claim 1, wherein the inner surface of the bearing opening is formed in a catenoid shape that is narrowest in the center and gradually expands toward the two-sided openings, thereby allowing the bearing pin to tilt in multiple directions within the bearing opening to compensate for misalignment. Claim 6 A bearing adapter according to claim 1, wherein a line passing through the approximate center axis of each connecting part points to the bearing. Claim 7 In claim 1, the main body is a bearing adapter formed by joining two substantially identical plate members by a clinch joint. Claim 8 A bearing adapter for a single-axis tracker comprising: a pair of tubular S-shaped curved members; a straight bridge member connecting the first ends of the curved members; a pair of connecting members formed at the second end of the curved members and inserted into the upper end of a truss leg; and a bearing opening formed in the bridge member; wherein the bearing opening is formed to rotatably receive a bearing pin. Claim 9 In claim 8, the bridge member defines a first plane, and the bearing adapter is formed in an axial direction substantially orthogonal to the first plane. Claim 10 In claim 8, the bearing pin inserted into the bearing opening supports the torque tube to form the rotation axis of the torque tube, forming a bearing adapter. Claim 11 A bearing adapter according to claim 8, wherein the inner surface of the bearing opening is formed in a catenoid shape that is narrowest in the center and gradually expands toward the two-sided openings, thereby allowing the bearing pin to tilt in multiple directions within the bearing opening to compensate for misalignment. Claim 12 In paragraph 8, a bearing adapter in which a line passing through the approximate center axis of each connection point to the bearing. Claim 13 A bearing adapter for a single-axis tracker having an offset drive assembly, comprising: a cardioid-shaped main body having a cusp in the center; a bearing opening formed through the main body; and a pair of connecting parts extending downward and outward from both sides of the lower end of the main body and coupled to the upper end of an inclined truss leg; wherein the connecting parts are fixed to each truss leg and configured to form an A-frame-shaped base structure together with the bearing opening. Claim 14 In claim 13, the bearing adapter is formed such that the cardioid-shaped main body includes an inverted S-shaped arm symmetrical around the cusp. Claim 15 A bearing adapter comprising a bearing pin that is seated on a bearing, in Clause 13. Claim 16 In paragraph 13, a bearing adapter in which one of the pair of connecting parts is shorter than the other. Claim 17 A bearing adapter according to claim 16, further comprising a sleeve for joining a short connecting portion to one of the truss legs. Claim 18 In paragraph 17, the sleeve is a bearing adapter that is a twist-lock sleeve. Claim 19 In paragraph 17, the sleeve is a crimp sleeve, which is a bearing adapter. Claim 20 A bearing adapter according to claim 15, wherein the inner surface of the bearing opening is formed in a catenoid shape that is narrowest in the center and gradually expands toward the two-sided openings, thereby allowing the bearing pin to tilt in multiple directions within the bearing opening to compensate for misalignment.

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