Patent Application
20240140733
The present disclosure relates generally to an apparatus, system, and method for arranging a flexible sheet or array of elements on a complex curved surface and specifically to the picking of a flat, flexible array of solar cells and placing on a doubly curved solar panel substrate.
The materials or components for manufacturing assemblies with complex curved surfaces are often flat and have some degree of flexibility. These components are required to conform to the curved surface in the assembly process. For doubly curved surfaces this can require a distortion of the material or component, such as expansion, contraction, bending, twisting, rotating, folding or shearing.
In the aircraft industry, for example, fabrication of carbon fiber composites for wings, fuselages, and other aircraft panels begins with a mold and sheets of carbon fiber material. Pre-cut sheets are arranged in the mold with precise positioning and flexing to achieve the required conformity. This is a challenging operation to automate since some areas of the sheet must be fixed while others can flex and/or slip. Conventional automation may employ an array of gripper heads which flexes between a flat configuration and the shape of a concave mold by combining mechanical actuation and gravity to create a smooth, doubly curved tool surface that matches the shape of the mold. However, problems occur when using this approach to move from a flat configuration to a convex surface because mechanical actuation (convex-inducing) and gravity (concave-inducing) oppose each other leading to deviations from the intended curvature. Another disadvantage is that active mechanical actuation may be more expensive to implement than a passive conformal alignment system.
In the solar panel market demand has emerged for flexible and/or curved solar panel(s) for use in various applications, for example buildings, vehicles, aircraft, and spacecraft. Damage and/or fracture of the delicate solar cells are problems that persist in current manufacturing processes of solar panels with complex geometries. Specifically, solar cell failure may be attributed to the stress caused by simple or complex bending, torsion, or other deformation within the solar cell during handling of the bare cell, strings of cells, or arrays of cells. Therefore, an important aspect of curved solar panel fabrication is the handling and arranging of solar cells to match complex panel shapes in any format such as single cells, strings of cells, or arrays of cells. Picking and placing of large, flexible arrays of elements when moving from a flat surface to a curved surface requires both a three-dimensional spatial transformation and precision alignment. It is particularly difficult to maintain the precision and alignment of the placed solar cells during subsequent operations, such as busbar soldering and/or lamination. Consequently, there is a long-felt need for an assembly tool and manufacturing process that provides damage-free handling, precision placement and holding registration of bare cells, strings of cells, or arrays of cells from a flat surface to a convex surface in the manufacturing of mobile and/or curved solar panels.
Conventionally, solar cells are partially assembled in a flat state wherein the cells and interconnects may be supported throughout the soldering operation. The assembly of cells into linear strings, i.e., rows, for example, is often automated as in the case of flat solar panel manufacturing. A string is composed of the solar cells and the intra-row interconnects, which form bendable mechanical connections as well as electrical connections between the cells. The strings are then either manually or robotically arranged into arrays on a flat substrate. Rows are connected via inter-row busbars, which are soldered in place on the substrate, often manually. Adapting this approach to curved surfaces, strings may be moved from a flat, partially assembled state to a curved, concave substrate and arranged to fill the surface, thereby forming an array, whereupon the rows are connected to each other with busbars. Note that, for a solar panel with a convex solar-facing surface, the assembly must occur in a concave mold to provide access to the back electrodes of the solar cells. The intra-row (string) interconnects typically allow for only a small amount of expansion or contraction between cells, if any. Therefore, the curvature of the substrate must be accommodated by the expansion or contraction of the space between the rows. This results in a slightly non-uniform array of cells whereby the spacing between rows is greater near the center of the array and smaller at the ends of the rows. Additionally, care must be taken to avoid overlapping cells at the ends of the rows or cracking of the cells may result.
Alternatively, cells may be pre-assembled into a complete array in a flat state. This approach has the advantage of avoiding busbar soldering on a curved surface where it is difficult to support the cells and busbars completely, which may subject the cells to cracking and/or the busbars to incomplete soldering. Moreover, problems of solar cell failure may occur due to the stress caused by simple or complex bending, torsion, or other deformation during the grabbing and transfer of an entire flexible cell array from a flat to a curved surface. For example, if the cells are connected in a serpentine manner, then each row must be supported individually throughout the transfer. Alternatively, temporary tethers may be disposed between the ends of the rows that are not soldered together. These approaches are complex and do little to reduce the risk of damage to the delicate solar cell array. Consequently, there is a long-felt need for an assembly tool and manufacturing process that provides for the picking and placing of a fully assembled array of solar cells from a flat surface to a convex surface where the assembled cells and interconnects are supported throughout the operation.
Some apparatuses and methods have been proposed to address these issues. In a first approach, a cell sub-assembly, such as a string or sub-array, or a full array is pre-laminated between sheets of encapsulant, with attention being paid to avoid full curing of the encapsulant such that it may be fully cured in a subsequent lamination step. The pre-lamination is performed with the cells and interconnects in a flat state. The resulting pre-laminate both protects the delicate cells and renders them easier to handle. The string, sub-array, or full array is then arranged and aligned on the curved surface of the substrate. In the case of the strings or sub-arrays, final interconnection via busbars must take place in-situ on the curved, and once again convex, surface. If a full array is used, the latter step may be avoided. However, for the case of full arrays, problems arise when the flat, two-dimensional pre-laminate is placed on the complex curved surface because an excess or dearth of encapsulant between the rows at the distortion points of the regular grid may result. One proposed solution is to add slits between the rows to accommodate expansion. How well this works is an open question. Consequently, there is a long-felt need for an assembly tool and manufacturing process that solves the problem of excess or lack of encapsulant between the rows at the distortion points of the regular grid.
In a second approach, a sub- or full array is assembled in a flat state including end-of-row busbars.
Temporary connections are then made between adjacent busbars, such as, for example, with adhesive tape, forming a border along two opposing sides, with the intra-row connectors forming a border along the intervening two sides. This complete border allows the sub- or full array to be handled by the corners. When this arrangement is transferred to the curved substrate, variable expansion between the rows accommodates the distortion of the array necessary to conform to the curved surface. The temporary border must be removed in-situ and the rows re-aligned to allow the necessary variable expansion or contraction, a complex, manual process that does little to reduce the risk of damage to the delicate solar cell array. Consequently, there is a need for a manufacturing process that avoids additional manufacturing process steps that increase cost, time, and/or solar cell failure due to the stress caused by bending, torsion, or other deformation during handling and transfer of an entire, flexible cell array from a flat to a curved surface.
Conventionally, some or all of these processes (placement, alignment, soldering, etc.) are performed manually and are labor intensive. As a result, complex geometry solar panel manufacturing can be difficult to do in a high-volume, high yield manner.
What is needed is a pick flat, place curved (PFPC) assembly tool, system and method that overcomes the aforementioned problems, and that is also suitable for automated manufacturing and capable of reliably and precisely picking a flexible array of elements and placing it on a curved surface with the required conformity, registration, and retention.
It is an object of the present disclosure to provide an apparatus, system and method for picking and placing of flexible sheets or arrays of elements from a flat surface to a convex curved surface requiring a spatial transformation and precision alignment.
It is an object of the present disclosure to provide an apparatus, system and method for picking a flexible array of solar cells assembled on a flat surface and placing it on a doubly curved solar panel.
It is an object of the present disclosure to provide an apparatus, system and method for maintaining the position of a solar cell array on a doubly curved solar panel for subsequent processing.
It is an object of the present disclosure to provide a doubly curved solar panel that is compatible with vehicular applications.
It is an object of the present disclosure to provide a doubly curved solar panel that may be mass produced at low cost.
Other desirable features and characteristics will become apparent from the subsequent detailed description, the drawings, and the appended claims, when considered in view of this summary.
Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings. In the drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified.
For a better understanding of the present disclosure, reference will be made to the following Detailed Description, which is to be read in association with the accompanying drawings, which are incorporated in and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations, wherein:
Non-limiting embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals represent like elements throughout. While the invention has been described in detail with respect to the preferred embodiments thereof, it will be appreciated that upon reading and understanding of the foregoing, certain variations to the preferred embodiments will become apparent, which variations are nonetheless within the spirit and scope of the invention. For a better understanding of the present invention, reference will be made to the following Detailed Description, which is to be read in association with the accompanying drawings, which are incorporated in and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations.
The terms “a” or “an”, as used herein, are defined as one or as more than one. The term “plurality”, as used herein, is defined as two or as more than two. The term “another”, as used herein, is defined as at least a second or more. The terms “including” and/or “having”, as used herein, are defined as comprising (i.e., open language). The term “coupled”, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically.
Reference throughout this document to “some embodiments”, “one embodiment”, “certain embodiments”, and “an embodiment” or similar terms means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments without limitation.
The term “or” as used herein is to be interpreted as an inclusive or meaning any one or any combination. Therefore, “A, B or C” means any of the following: “A; B; C; A and B; A and C; B and C; A, B and C”. An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive.
The drawings featured in the figures are provided for the purposes of illustrating some embodiments of the present invention, and are not to be considered as limitation thereto. Term “means” preceding a present participle of an operation indicates a desired function for which there is one or more embodiments, i.e., one or more methods, devices, or apparatuses for achieving the desired function and that one skilled in the art could select from these or their equivalent in view of the disclosure herein and use of the term “means” is not intended to be limiting.
A pick-and-place assembly tool, system and method 400 is illustrated in
The plate 412 may be fitted with connector elements 413a, 413b, 414a, and 414b which flexibly join the gripper head 411a to its nearest neighbors in the gripper head array 410. The connector elements 413a, 413b, 414a, and 414b may be tailored to provide various spring-like functionalities, such as bending, elongation/compression, torsion, or shear. In this embodiment, the deformation of intra-row connector elements 413a-b is primarily restricted to bending, as shown by the degrees of freedom indicators 413c. The degrees of freedom are marked χ where disallowed or very limited, ˜ where controlled or somewhat limited, and are unmarked where minimally limited. The inter-row connector elements 414a and 414b, on the other hand, may be chosen to allow expansion/contraction, bending and torsion 414c between the rows of solar cells, which are mechanically uncoupled, so as to allow the distortion necessary to conform to the complex curved surface of the substrate. Other arrangements of springs or spring-like elements with different degrees of freedom are possible and the present embodiment shall not be construed as limiting. The connector elements 413a, 413b, 414a and 414b may be of various types and materials, such as, for example, metal springs, articulated joints, or elastomer sheets, among others. Metal springs may be of various types, including standard constant-force springs, rectangular springs, torsion springs, and the like. In the present embodiment, elastomer sheets couple nearest neighbor heads in the gripper head array 410 and are joined to the gripper head plate 412 with adhesive. Alternatively, the sheets may be coupled to the plate 412 with clamps, fasteners or other suitable means. In the present embodiment, control of element spacing is achieved though the incorporation of variable durometer elastomer sheets disposed between the plates 412.
For example, higher durometer sheets may be disposed between heads along a row, which require a fixed spacing, and lower durometer sheets may be disposed between heads of adjacent rows, which may have a variable spacing.
In
The PFPC assembly tool may be dynamically or reconfigurably adapted to picking and placing of different quantities and arrangements of elements. This may be achieved in several ways. In a first embodiment, a vacuum regulating or on/off valve may be disposed in-line for each gripper head. The individually addressable valves may be programmatically configured to supply vacuum to a subset of the gripper heads in the array. This approach further allows for dynamic configurability for purposes such as the intra-row gap shrinkage previously mentioned. Alternatively, the vacuum lines may be joined into a manifold comprising a removable baffle that masks the flow of vacuum to the unused gripper heads, while allowing it to flow to gripper heads in service. To reconfigure the tool for a different component or product, a component-specific baffle is inserted into the manifold thereby selecting which gripper heads are vacuum enabled and which are not. This approach has the advantage of simplicity and reduced cost.
While certain configurations of structures have been illustrated for the purposes of presenting the basic structures of the present invention, one of ordinary skill in the art will appreciate that other variations are possible which would still fall within the scope of the appended claims. Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
This application is a conversion of, and claims the benefit of, co-pending U.S. Provisional Patent Application No. 63/381,866, entitled “Pick Flat Place Curved Assembly Tool, System and Method”, filed on Nov. 1, 2022, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63381866 | Nov 2022 | US |
