Membrane holding device with spacer device and method

Abstract

A membrane holding device (100) for a system for laminating a laminate (30), in particular a photovoltaic module, in a laminate chamber (50) comprising: a membrane (110) to close the laminate chamber (50); a membrane clamping device (120) designed to hold the membrane (110) in a clamping frame and to apply it to the laminate (30); and a spacer device (130) which is attached to the membrane tensioning device (120) and is designed to be placed laterally next to the laminate (30) when the membrane (110) is applied to the laminate (30) and to suppress edge compression of the laminate (30) during lamination, wherein the membrane tensioning device (120) is vertically movable in order to position the membrane (110) together with the spacer device (130) around the laminate (30), and wherein the spacer device (130) forms a frame around the laminate (30) such that when the membrane (110) is applied to the laminate (30) the spacer device (130) is flush with the laminate (30).

Description

[0001] The present invention relates to a membrane holding device with a spacer device for a lamination system and to a method for manufacturing the membrane holding device. BACKGROUND

[0002] The production of photovoltaic modules involves laminating layers of a laminate (layer stack) under pressure and elevated temperature. Membrane laminators are commonly used for this lamination process. This lamination can be largely automated by a system that transports a large number of such laminates into a lamination chamber. Inside the chamber, a membrane clamped in a frame is pressed down onto the laminate to be laminated. Simultaneously, heat is applied to the laminate, and a suction device reduces the pressure around it.

[0003] Under the pressure of the membrane, whose surface area extends beyond that of the laminate, over-compression can occur in the laminate's edge regions. This can lead to so-called edge pinching, a reduction in thickness at the laminate's edge. This can generate tensile forces within the laminate, which can cause delamination immediately after production or, for example, breakage of a cover glass layer over a longer period. State-of-the-art technology can be found, for example, in US 2012 / 0273126A1 and WO 2011 / 089474A2.

[0004] Fig. Figure 5 shows an illustration of how such edge compression occurs. The left side of the figure shows a cross-section of a system for laminating a laminate 30. A membrane 110 is pressed onto the laminate 30 for lamination (e.g., with air pressure). In membrane laminators, such a membrane 110 can, for example, have a thickness of up to 8 mm and an area on the order of several square meters. In the edge regions, a surface of the membrane 110 extends beyond the laminate 30, so that the mechanical pressure exerted on the laminate 30 by the membrane 110 compresses the laminate 30 more strongly in the edge region than in the middle region. This results in edge compression of the laminate 30. The right side of the figure shows an enlarged cross-section of the compressed edge region of the laminate 30.The laminate 30 comprises two glass layers 33 arranged around a layer 37, which contains a plastic and embedded solar cells. The glass layers can, for example, have thicknesses of up to 2.5 mm, and the plastic layer, for example, a thickness of one millimeter, so that the laminate 30 can have a thickness of, for example, 5 mm when uncompressed. Towards the edge of the laminate 30 (on the right side of the figure), the thickness of the laminate 30 is reduced due to over-compression. This causes persistent stresses that limit the service life and quality of the photovoltaic modules.

[0005] Therefore, there is a need for a cost-effective and efficient suppression of edge compression in membrane laminators, which is also advantageously suitable for retrofitting membrane laminators already in operation, so that existing automated processes can continue to be maintained. BRIEF DESCRIPTION OF THE INVENTION

[0006] The aforementioned problem is solved at least partially by a membrane holding device according to claim 1, a system for laminating a laminate according to claim 7, and a method for manufacturing a membrane holding device according to claim 12. The dependent claims relate to advantageous embodiments of the subject matter of the independent claims.

[0007] The present invention relates to a membrane holding device for a system for laminating a laminate, in particular a photovoltaic module, in a laminate chamber. The membrane holding device comprises a membrane designed to close the laminate chamber, a membrane clamping device designed to hold the membrane in a clamping frame and to apply it to the laminate, and a spacer device connected to the membrane clamping device and designed to be positioned laterally next to the laminate when the membrane is applied to the laminate and to suppress edge compression of the laminate during lamination.

[0008] In exemplary embodiments, a membrane is a diaphragm, often made of silicone-containing material or rubber, designed to exert mechanical pressure on one or more laminates simultaneously—for example, by means of overpressure / underpressure (e.g., by a fluid such as air) on a side facing away from / towards the laminate. For this purpose, a tensioning frame can be lowered onto the underlying laminate by the membrane tensioning device, causing the membrane to stretch over the laminate and thus seal the laminate chamber. The mechanical pressure on the laminate can be applied indirectly, for example, via a sheet placed between the membrane and the laminate to protect the laminate and to facilitate removal after lamination. The laminate can be automatically fed onto a conveyor belt or...The transport sheet is transported into the laminate chamber, where it can withstand the pressure, for example, by means of a device supporting the belt.

[0009] The spacer device can, for example, be a frame rigidly connected to the tensioning frame or the membrane tensioning device. When the membrane is applied, this frame is supported on the conveyor belt or transport sheet next to the laminate, supporting the membrane at a height corresponding to the intended thickness of the laminate, over an area extending beyond the laminate. In this way, the frame prevents additional pressure on an edge area of ​​the laminate that the membrane would otherwise exert due to tension. Advantageously, the frame is designed such that, when supported, a gap to the laminate ensures tolerance regarding the position of the laminate on the transport sheet, while sufficiently reducing the mechanical pressure exerted by the membrane at an edge of the laminate.

[0010] Optionally, the spacer device has openings to facilitate the escape of gas (e.g., during extraction) from an area in and around the laminate when the membrane is applied to the laminate.

[0011] Particularly when laminating a photovoltaic module, air inclusions in the laminate should be avoided by ensuring that air can escape from the laminate during lamination. In some embodiments, the frame does not need to be continuous and can have holes to allow air to escape and / or to vent escaping air in a controlled manner. In particular, the holes can also be adapted to a device for extracting the gas (e.g., using a vacuum pump).

[0012] Optionally, the spacer device has recesses or forms a gap to the laminate to allow or absorb the escape of material (e.g., melting material) during lamination.

[0013] A laminate for photovoltaic modules can, for example, comprise a layer of a plastic material such as ethylene vinyl acetate (EVA) or polyolefin (PO) sandwiched between two glass plates, enclosing a multitude of photovoltaic cells and their associated contacts. During lamination, this plastic material can ooze out of the laminate laterally between the glass plates. The spacer can be designed, for example, by means of a suitable frame shape, to allow and / or facilitate this oozing of plastic material. The frame can thus have indentations, widenings, grooves, channels, and / or other recesses on a side facing the laminate, providing sufficient space for the escaping molten EVA.

[0014] Optionally, the spacer device has chamfers to extend the service life of the membrane.

[0015] Bevels can be formed, in particular, on the side of a frame of the spacer device facing away from the laminate, so that the membrane adapts to the shape of the frame due to the bevel. Without bevels, sharp edges of the frame can cut into the membrane and damage it.

[0016] According to the invention, the membrane tensioning device is vertically movable to position the membrane, together with the spacer device, around the laminate. It can be lowered before lamination and raised again afterward. Optionally, the spacer device can also form a frame around the laminate such that, when the membrane is applied to the laminate, the spacer device is flush with the laminate. This flush finish is intended to prevent excessive deflection, as occurs with conventional systems. This can be achieved, for example, by having the spacer device at the same height as the laminate and extending as close as possible to the laminate, at least on the membrane side. Optional recesses could be formed below this.

[0017] The height of the spacers can also exceed the height of the laminate. This can be the case, in particular, if a gap exists between the laminate and the spacers when the membrane is pressed onto the laminate; the spacers can, for example, protrude 5, 10, or 20 percent above the laminate's thickness. The height of the spacers can depend on the distance between the laminate and the spacers.

[0018] Optionally, the spacer device (e.g., as a frame) may consist of at least one of the following materials: steel, Teflon, silicone, hard rubber, plastic.

[0019] The spacer is advantageously designed to prevent material that oozes from the laminate during lamination from adhering to it, using a suitable material. Therefore, the aforementioned materials can also be coated with a non-stick layer (e.g., polytetrafluoroethylene, PTFE, or Teflon) to allow for easy removal of adhering EVA, for example.

[0020] The present invention also relates to a system for laminating a laminate, in particular a photovoltaic module, in a laminate chamber, wherein the system comprises a membrane holding device according to the preceding description.

[0021] Optionally, the system includes a transport sheet designed to transport the laminate after it has been laid down, with the transport sheet having a circumferential shape.

[0022] The transport sheet is advantageously made of a material such as Teflon, which allows the laminate to be easily lifted from the transport sheet after lamination and prevents any material that oozes out of the laminate from adhering to the sheet. Furthermore, the transport sheet is sufficiently pressure- and heat-resistant to ensure its function as a support for the laminate during the lamination process.

[0023] Optionally, the system includes a heating device designed to supply heat during lamination.

[0024] Such a heating device can be designed, in particular, beneath the transport sheet. Temperatures achieved by the heating device during the lamination process in exemplary embodiments are, for example, up to 180°C.

[0025] Optionally, the system includes an extraction device designed to draw gas from the lamination chamber during membrane application to the laminate, thereby creating a vacuum. This vacuum can be used both to generate the mechanical pressure required for lamination and to counteract air inclusions in the laminate.

[0026] Optionally, the system includes a release sheet, which is formed between the membrane and the laminate when the membrane is applied to the laminate, to facilitate the removal of the membrane from the laminate after lamination.

[0027] Such a release sheet can be designed as a continuous band or arc. In some embodiments, the release sheet can run between the membrane and the spacer. When the membrane is applied to the laminate, the release sheet is then located both between the membrane and the laminate, and between the membrane and the spacer. In other embodiments, the release sheet can also run below the spacer. During lamination, the release sheet then lies section by section between the membrane and the laminate, as well as between the transport sheet and the spacer. An advantage of the latter embodiment is that the intervening release sheet prevents the laminate from sticking to the spacer.

[0028] Exemplary embodiments also relate to a method for manufacturing a membrane holding device for a system for laminating a laminate, in particular a photovoltaic module, as previously described. The method comprises: - Providing a membrane; - Securing the membrane in a membrane clamping device; and - Connecting a spacer device to the membrane clamping device so that the membrane in the membrane clamping device moves together with the spacer device before and after lamination, and the spacer device suppresses deflection of the membrane during lamination to avoid edge compression of the laminate during lamination.

[0029] Exemplary embodiments also relate to a method for suppressing edge compression of a laminate, in particular a photovoltaic module, when applying a membrane to the laminate, which is formed in a membrane tensioning device with a spacer device. The method comprises the following steps: • Applying the membrane over the laminate using the membrane tensioning device, whereby • Place the spacer next to the laminate, • Applying mechanical pressure through the membrane, while suppressing edge compression of the laminate by the spacer device.

[0030] The spacer device is designed to prevent the edge of the laminate from deflecting during lamination, specifically through mechanical support provided by the spacer device. The spacer device supports the membrane directly and / or indirectly (for example, via a release sheet between the membrane and the spacer device) in an area of ​​the membrane that extends beyond the laminate, thus reducing the additional pressure exerted on the edge of the laminate by the membrane tension.

[0031] Advantages of exemplary embodiments of a membrane holding device with a spacer device as described above include, in particular, the possibility of cost-effective manufacturing of the spacer device, which can simply be adapted to the geometry of an existing membrane lamination system and can also be retrofitted. BRIEF DESCRIPTION OF THE FIGURES

[0032] The embodiments of the present invention are better understood from the following detailed description and the accompanying drawings, which, however, should not be understood as limiting the disclosure to the specific embodiments, but merely serve for explanation and understanding. Fig. Figure 1 shows cross-sections of a membrane holding device with a spacer for a lamination system. Fig. Figure 2 shows a top view of a membrane holding device with a spacer for a laminating system. Fig. Figure 3 shows cross-sections of another embodiment of a membrane holding device with a spacer for a laminating system. Fig. Figure 4 shows a top view and cross-sections of part of a membrane holding device with a spacer device having recesses to allow material to escape. Fig. Figure 5 shows a representation of how edge compression occurs in a conventional laminating system without a spacer device. Fig. Figure 6 shows steps of a procedure for suppressing edge compression of a laminate. DETAILED DESCRIPTION

[0033] Fig. Figure 1 shows two cross-sections arranged one above the other of an embodiment of parts of a membrane holding device 100 for a system for laminating a laminate 30. The laminate 30 can in particular be a photovoltaic module to be manufactured.

[0034] The upper cross-section shows a laminate chamber 50, which is formed by the membrane holding device 100 and, in particular, by the membrane 110. The membrane 110 is held in a clamping frame by a membrane clamping device 120. A spacer device 130 is attached to the membrane clamping device 120; this spacer device can encompass approximately one lamination frame around the laminate 30 to be produced. The laminate 30 enters the laminate chamber on a transport sheet 200 beneath the membrane clamping device 120.

[0035] The lower cross-section shows the contents of the upper cross-section in a situation where the membrane 110 is applied to the laminate 30 and exerts mechanical pressure (represented by several vertical arrows above the membrane 110) on the laminate. Advantageously, the transport sheet 200 and the laminate 30 remain stationary. The spacer device 130, or lamination frame, is positioned laterally next to the laminate 30 and supports an area of ​​the membrane 110 that extends beyond the laminate 30. This prevents edge compression of the laminate 30 during lamination.

[0036] The spacer 130 protects the laminate edges from over-pressing. Advantageously, the lamination frame of the spacer 130 is only slightly larger than the outer edges of the laminate and has a height at least equal to that of the laminate 30 being produced. The distance between the spacer 130 and the laminate 30 depends on the positioning accuracy of the laminate 30 on the transport sheet 200. This positioning accuracy varies between different lamination systems. In some cases, the distance can be on the order of 3 to 7 mm. The spacer 130 is made of a temperature- and pressure-resistant material. Openings in the spacer 130 or in the lamination frame, positioned perpendicular to the laminate 30, can facilitate evacuation of the laminate 30 during the lamination process.

[0037] The spacer device 130 is mounted above the laminate(s) 30 and below the membrane 110 in the laminator process chamber 50. Attachment to the membrane tensioning frame 120 is a suitable mounting solution. The spacer device can therefore also be integrated into existing systems. Before or during the lowering of the laminator chamber lid, the spacer device 130 also lowers and rests next to the laminate 30, so that the laminate is enclosed by the spacer device 130 or a lamination frame.

[0038] Overall, the spacer unit 130 enables an automated process without manual handling and laminates 30 without edge compression. Furthermore, it facilitates a stable lamination process, as lamination defects such as glass / backsheet misalignment are significantly reduced, thus lowering the risk of bubble formation and / or other optical defects.

[0039] Fig. Figure 2 schematically shows a top view of a membrane holding device 100 with a spacer device 130 for a laminating system. In particular, four laminates 30 are laminated simultaneously through the same membrane 110. The outermost frame shown in the figure represents the membrane clamping device 120 and thus the surface of the membrane 110. A spacer device 130, shown here by dashed lines, is mounted within the membrane clamping device 120 and is positioned between the laminates 30 during lamination. In the illustrated embodiment, the spacer device 130 also includes parts of lamination frames arranged transversely to a transport direction (which here can point approximately to the right side of the figure) around the laminates 30.

[0040] Advantageously, the lamination frames of the spacer unit 130 are only slightly larger than the outer edges of the laminate. The arrangement or geometry of the spacer unit 130 and the lamination frames is variable and depends on the module and machine geometry.

[0041] Fig. Figure 3 shows cross-sections of another embodiment of a membrane holding device 100 with a spacer device 130 for a laminating system. Similar to the one in Fig. Figure 1 shows an upper cross-section of parts of a membrane holding device 100, in particular a membrane clamping device 200 with membrane 110 and a spacer device 130, here designed to provide a lamination frame for each of two adjacent laminates 30. The laminates 30 lie on a transport sheet 200, which transports the laminates 30 perpendicular to the cross-sectional area. The transport sheet 200 advantageously has a non-stick coating made of a material such as Teflon, which prevents the laminates 30 or material that has seeped out of one of the laminates 30 during lamination from adhering to it, even when heated.

[0042] A release sheet 300 runs between the spacer device 130 and the membrane 110, designed, for example, as a band rotating synchronously with the transport sheet 200 in the same direction. In laminating systems, the thickness of the release sheet 300 can be, for example, 0.3 mm.

[0043] In the illustrated embodiment, the release sheet 300 runs between the membrane 110 and the spacer device 130. This can be particularly advantageous for achieving optimal lamination results. In other embodiments, however, the release sheet 300 also runs below the spacer device 130, i.e., between the spacer device 130 on one side and the laminate 30 or the transport sheet 200 on the other, so that when the membrane 110 is lowered onto the laminate 30, the spacer device 130 comes to rest on the release sheet 300. This can be advantageous for machine design reasons. In particular, this variant can simplify the subsequent installation of the spacer device in an existing lamination machine.Another advantage of this embodiment is that the intervening release sheet 300 prevents the laminate 30 from sticking to the spacer device 130 (through the encapsulation material, EVA).

[0044] Under the transport sheet 200 a heating device 400 in the form of a heating plate is shown, which supplies heat to the laminates 30 during lamination.

[0045] A cross-section below shows the system described above during lamination. The membrane 110 presses down on the release sheet 300, which then transmits the pressure to the laminates 30. The release sheet 300 protects the laminates 30 and is made of a material that facilitates the removal of the membrane 110 from the laminates 30 at the end of the lamination process. The mechanical pressure exerted by the membrane 110 on the laminates 30 is reduced in the edge areas of the laminates 30 by the spacer 130, thus preventing edge compression of the laminates 30.

[0046] Fig. Figure 4 shows optional details of the spacer device 130 in a further embodiment. The top of the figure shows a top view of four laminates 30 and part of a membrane tensioning device 120 with the spacer device 130. The spacer device 130 forms frames for the laminates 30 and is connected to the membrane tensioning device 120 at certain points. Below are two cross-sections through the top view in the upper part of the figure. The membrane tensioning device 120 is lowered in each case, so that the spacer device 130 rests on a transport sheet 200.

[0047] An upper cross-section shows a shape of the spacer device 130 in the area of ​​the connections with the membrane tensioning device 120. The frame formed by the spacer device 130 around the laminates 30 has a height above the conveyor belt 200 corresponding to the height of the laminates 30; in other embodiments, the spacer device may also be somewhat higher. Parts of the spacer device 130 have a shape that allows material to escape from the laminates 30 during lamination. In particular, for example, plastic can escape from the plastic layer 37 (see figure 1). Fig. 5) emerge from the laminate in the center during lamination. In the illustrated embodiment, the aforementioned shape of the spacer device 130 is the chamfer 133. The spacer device 130 reduces the outflow of encapsulation material (e.g., EVA) because the laminate edges are not overpressed. This already reduces or minimizes the risk of sticking. The chamfer 133 gives the spacer device 130 an angle towards the laminate edge so that the outflowing encapsulation material has as little contact area as possible with the spacer device 130. Outflowing material passes through this shape onto the conveyor belt 200. It is advantageous if the spacer device 130, like the conveyor belt 200, has a non-stick coating made of a material that prevents the outflowing material from adhering (such as Teflon).

[0048] A lower cross-section shows a form of the spacer device 130 away from the connections with the membrane tensioning device 120. As in the upper cross-section, the spacer device 130 has chamfers 133 that allow material to escape from the laminate. In addition, the spacer device 130 has chamfers 137 that serve to protect the membrane 110 (not shown here) pressed onto it from above. Sharp edges can damage the membrane 110, which can be less than one centimeter thick. Particularly in embodiments where the release sheet runs above the laminate 30 but below the spacer device 130 (and the membrane 110), sharp edges can also damage the release sheet. The chamfers 137 allow the membrane 110 or the release sheet 300 to conform to the laminate, thus increasing the contact area for the membrane 110 or the release sheet, and consequently also extending the service life of the membrane 110 or the release sheet.of Release Sheet 300.

[0049] Fig. Figure 6 shows the steps of a method for manufacturing a membrane holding device 100 for a system for laminating a laminate 30. The laminate 30 can, in particular, be that of a photovoltaic module. A first step comprises providing S100 a membrane 110. A further step comprises securing S120 the membrane 110 in a membrane clamping device 120. Additionally, S130 a spacer device 130 is connected to the membrane clamping device 120, so that the membrane 110 is moved by the membrane clamping device 120 together with the spacer device 130. In particular, the membrane 110 is applied to the laminate 30 for lamination and lifted off the laminate again after lamination. During lamination, the spacer device 130 prevents the membrane 110 from deflecting in order to avoid edge compression of the laminate 30.

[0050] The features of the invention disclosed in the description, claims and figures may be essential for the realization of the invention, either individually or in any combination. REFERENCE MARK LIST 30 laminates (e.g., stacked layers for photovoltaic modules) 33 glass plate(s) 37 Plastic layer (e.g. EVA) 50 laminate chamber 100 Membrane holding device 110 Membran 120 Membrane tensioning device 130 Spacing device 133 Recess for drainage of escaping material 137 Bevel to increase the service life of the membrane 200 Transport sheets 300 Release Sheet 400 heating unit

Claims

A membrane holding device (100) for a system for laminating a laminate (30), in particular a photovoltaic module, in a laminate chamber (50) comprising: a membrane (110) for closing the laminate chamber (50); a membrane clamping device (120) designed to hold the membrane (110) in a clamping frame and to apply it to the laminate (30);and a spacer device (130) which is attached to the membrane tensioning device (120) and is designed to be placed laterally next to the laminate (30) when the membrane (110) is applied to the laminate (30) and to suppress edge compression of the laminate (30) during lamination, wherein the membrane tensioning device (120) is vertically movable to position the membrane (110) together with the spacer device (130) around the laminate (30), and wherein the spacer device (130) forms a frame around the laminate (30) such that when the membrane (110) is applied to the laminate (30), the spacer device (130) is flush with the laminate (30). The membrane holding device (100) according to claim 1, wherein the lamination comprises forming a negative pressure in the laminate chamber (50), and wherein the spacer device (130) has openings to facilitate the escape of gas from an area in and around the laminate (30) when the membrane (110) is applied to the laminate (30). The membrane holding device (100) according to one of the preceding claims, wherein during lamination a fusion of ethylene vinyl acetate takes place in the laminate (30), and wherein the spacer device (130) has recesses (133) or forms a gap to the laminate (30) to receive escaping ethylene vinyl acetate during lamination. The membrane holding device (100) according to one of the preceding claims, wherein the spacer device (130) has chamfers (137) to extend the service life of the membrane (110). The membrane holding device (100) according to one of the preceding claims, wherein the spacer device (130) comprises at least one of the following materials: - steel, - plastic, - silicone, - hard rubber, - base material with a non-stick coating. A system for laminating a laminate (30), in particular a photovoltaic module, in a laminate chamber (50), comprising: a membrane holding device (100) according to one of the preceding claims. The system according to claim 7, which further comprises a transport sheet (200) which is designed to transport the laminate (30), wherein the transport sheet (200) is designed to be circumferential. The system according to claim or claim 8, further comprising a heating device (400) which is formed on a side of the transport sheet (200) facing away from the laminate (30) in order to supply heat for lamination. The system according to one of claims 7 to 9, further comprising an extraction device which is designed to extract gas from the lamination chamber (50) when applying the membrane (110) to the laminate (30) and thus create a negative pressure. The system according to one of claims 7 to 10, further comprising a release sheet (300) which is formed between the membrane (110) and the laminate (30) to facilitate the separation of the membrane (110) from the laminate (30) after lamination. Method for manufacturing a membrane holding device (100) for a system for laminating a laminate (30), in particular a photovoltaic module, comprising the following steps: Providing (S100) a membrane (110); Fixing (S120) the membrane (110) in a membrane clamping device (120);Connecting (S130) a spacer device (130) to the membrane clamping device (120) such that the membrane (110) moves in the membrane clamping device (120) together with the spacer device (130) before and after lamination and the spacer device (130) suppresses deflection of the membrane (110) during lamination in order to avoid edge compression of the laminate (30) during lamination, wherein the membrane clamping device (120) is vertically movable to position the membrane (110) together with the spacer device (130) around the laminate (30), and wherein the spacer device (130) forms a frame around the laminate (30) such that when the membrane (110) is applied to the laminate (30), the spacer device (130) is flush with the laminate (30).

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