Expansion element

Abstract

In order to control the expansion of an expansion element on a structural element in a vehicle body, a planar fabric is used. Here, the planar fabric is covered on both sides with an expandable material. The expansion of the expansion element in a direction perpendicular to the planar fabric is at least 15% greater than the expansion element without the planar fabric.

Description

[0001] This application is a divisional application of the Chinese patent application with application number 202080040712.X.

[0002] The invention relates to an expansion element on a structural element in a bodywork, more particularly a bodywork of a motor vehicle, and also to a method for joining two structural elements of a bodywork using such an expansion element.

[0003] The bodies of motor vehicles are often designed with lightweight structures. In these cases, it is often desirable to purposefully reinforce these lightweight structures at certain locations. For example, areas of the body that form cavities can be reinforced by inserted reinforcement elements. On the other hand, reinforcement elements can also be bonded to planar areas of the body in order to provide them with reinforcement.

[0004] A known method for reinforcing lightweight structures in motor vehicles is to arrange so-called strips or mats on the body elements, which are then foamed and cured in a painting oven. Such strips or mats can be used, for example, to connect two substantially opposite structural elements of the body together.

[0005] A first known product of this type is described in US 2003 / 0183317 A1. In this case, one or more reinforcing layers are arranged in the expandable material, which ultimately mechanically reinforce the reinforcing element. The reinforcing layers can be formed from different kinds of materials.

[0006] Another similar product is known and is described in WO 2015 / 011687 A1. Here again, a fiber layer or a nonwoven web is integrated into the expandable material in order to mechanically reinforce the entire reinforcing element.

[0007] In addition, similar reinforcing elements in the form of laminates are also known. For example, WO 2011 / 109699 A1 discloses such a laminate. In each case, a layer of expandable material is arranged on a foil. In order to achieve a connection between the layers, the surface tensions of the foil and the expandable material are adapted to each other. In addition, the foil is used to control the expansion of the expandable material arranged thereon.

[0008] A disadvantage of the reinforcement elements known to date is that, on the one hand, the expansion in a direction perpendicular to the layer plane usually takes place inadequately or hardly under control. As a result, in order to be able to close certain gaps between two structural elements of the vehicle body by expansion of the reinforcement element, it is necessary to use larger and therefore heavier reinforcement elements. Furthermore, in the known solutions, it is also disadvantageous that, despite corresponding measures, the connection between the layers of the reinforcement element is still insufficient.

[0009] The object of the invention is therefore to provide a reinforcing element or expansion element of the aforementioned type which, on the one hand, has an improved expansion in a direction perpendicular to the layers of the expansion element and, on the other hand, enables an improved connection between the individual layers of the expansion element. Furthermore, the expansion element should be cost-effective and easy to produce and use.

[0010] This object is firstly achieved by using a planar fabric for the controlled expansion of an expansion element on a structural element in a vehicle body, wherein the planar fabric is covered on both sides with an expandable material and wherein the expansion of the expansion element in a direction perpendicular to the planar fabric is at least 15% greater than in the case of an expansion element without the planar fabric.

[0011] The above object is also achieved by a method for connecting two structural elements of a vehicle body using an expansion element, the method comprising the following steps:

[0012] - providing expandable material;

[0013] -providing a flat fabric;

[0014] - forming an expansion element comprising said expandable material and said planar fabric, wherein said planar fabric is covered on both sides by the expandable material; and

[0015] - expanding the expansion element, wherein the expansion of the expansion element in a direction perpendicular to the planar fabric is at least 15% greater than in the case of an expansion element without the planar fabric.

[0016] The solution proposed here firstly offers the advantage that due to the use of a flat fabric between the layers of expandable material, an improved connection between the layers can be achieved. It seems important here that when the expandable material solidifies, the expandable material also penetrates through the flat fabric and crosslinks. This would theoretically result in a single, solidified and crosslinked expansion element that is not functionally differentiated.

[0017] Surprisingly, it has been found that the use of a flat fabric in such an expandable material results in a more pronounced expansion in a direction perpendicular to the plane of the flat fabric than when using a foil. Here, the generally lower weight of the flat fabric relative to the foil may play a role, as well as the crosslinking through the flat fabric as described above.

[0018] Thus, a method and a use can be provided, respectively, with which expansion in a desired direction can be significantly improved, in particular for closing a gap between two substantially opposite elements. The solution described here therefore offers the advantage that smaller or lighter expansion elements can be used than in the case of known expansion elements.

[0019] Furthermore, due to a more controlled expansion in a defined direction, an undesired foam filling of adjacent areas is obtained. For example, it is usually undesirable to fill the area adjacent to the area to be reinforced with foam, because otherwise, for example, holes punched in the sheet The assembly component can no longer be used.

[0020] Preferred exemplary embodiments and modifications are now described below.

[0021] In an exemplary development, the expansion of the expansion element in a direction perpendicular to the planar fabric is at least 20% or at least 25% or at least 30% greater than in the case of an expansion element without the planar fabric.

[0022] In one exemplary embodiment, the planar fabric is a mesh.

[0023] In an alternative exemplary embodiment, the two-dimensional fabric is a knit, a woven, a laid scrim, a braid or a knit.

[0024] In an exemplary embodiment, the basis weight (Dicke) of the planar fabric is 5 to 500 g / m 2 , preferably 5 to 300 g / m 2 , preferably 5 to 100 g / m 2 , more preferably 5 to 50 g / m 2 .

[0025] In an exemplary embodiment, the planar fabric has a thickness of 10 to 1000 μm, preferably 50 to 500 μm.

[0026] The use of a flat fabric with such a thickness or such a weight per unit area has the advantage that a particularly light flat fabric can be used. This has the effect that expansion in a direction perpendicular to the flat fabric is not hindered by the weight of the flat fabric and that the entire expansion element can be constructed to be as light as possible.

[0027] In an exemplary embodiment, the mesh size of the planar fabric is 0.5-15 mm, preferably 1-10 mm, more preferably 2-7 mm.

[0028] Providing such a mesh size has the advantage that the cross-linking through the flat fabric is thereby improved when the expandable material solidifies.

[0029] In an exemplary embodiment, the fibers of the planar fabric have a multi-directional orientation.

[0030] The use of multidirectionally oriented fibers provides the advantage that the expansion of the planar fabric in the vicinity is effectively limited in all directions parallel to the plane of the planar fabric. The expansion of the expandable material in a direction perpendicular to the plane of the planar fabric is thus enhanced.

[0031] In an exemplary embodiment, the planar fabric has substantially no effect on the tensile strength of the intumescent element in the cured state.

[0032] This in turn has the advantage that, if the mechanical properties are determined solely by the expandable material, a particularly light and coarse-pored flat fabric can be used. This brings about the advantages described above.

[0033] In an exemplary embodiment, cross-links of the expandable material through the planar fabric are formed as the expandable material cures.

[0034] Such cross-linking of the planar fabric offers the advantage that an improved connection between the individual elements or layers of the expansion element can thereby be ensured.

[0035] In an exemplary embodiment, the planar fabric comprises one or more of the following materials: glass fibers, carbon fibers or plastic fibers (particularly polyester fibers).

[0036] The use of plastic fibers in particular offers the advantage that a particularly cost-effective and lightweight flat fabric can thereby be provided.

[0037] In an exemplary embodiment, the surface coverage of the planar fabric is less than 80%, preferably less than 50%, and more preferably less than 30%.

[0038] "Surface coverage" in the context of the present invention refers to the percentage of coverage of the fibers on a plane in a top view of the planar fabric (the viewing direction perpendicular to the plane of the planar fabric).

[0039] Thus, a surface coverage of 100% means that the fibers of the fabric completely cover the plane of the fabric, so that there is no space at all between the fibers in a top view. Correspondingly, a surface coverage of 50% means that half of the surface is covered by fibers in a top view, and the other half of the surface consists of spaces between the fibers.

[0040] In one exemplary embodiment, a plurality of planar fabrics are used or provided.

[0041] In an exemplary development, between two and five, or between two and four, or between two and three, or exactly two, or exactly three planar fabrics are used or provided to form the expansion element.

[0042] It is found in experiments that by providing a plurality of planar fabrics, the effect of strengthening expansion in a direction perpendicular to the planar fabrics can be enhanced. Therefore, the appropriate number and arrangement of the planar fabrics can be selected according to the total thickness and expansion rate of the expandable material.

[0043] In an exemplary embodiment, the one or more planar fabrics are arranged symmetrically in the expansion element.

[0044] In an exemplary embodiment, the one or more planar fabrics are arranged in the expansion element in such a way that for each layer formed by the planar fabric, the layer thickness of the expandable material is at least 10% of the total thickness of the expansion element.

[0045] In an advantageous development, the minimum layer thickness of the expandable material is at least 15% or at least 20% or at least 25% or at least 30% relative to the total thickness of the expansion element.

[0046] In an alternative embodiment, one or more planar fabrics are arranged asymmetrically in the expansion element.

[0047] In an exemplary embodiment, the method described at the outset comprises the additional step of adhering the expansion element to one of the structural elements.

[0048] In a first exemplary development, the expandable material is viscous at room temperature, the expansion element is separated from the carrier element before it is arranged on the structural element, and the expansion element has a handle foil on one side.

[0049] In a second alternative development, the expandable material is not viscous at room temperature and the expansion element has an adhesive film on one side for adhesion to the structural element.

[0050] The advantage of these two exemplary developments is that the expansion element proposed here can therefore be used in the form of a belt or in the form of a mat.

[0051] In one exemplary embodiment, when forming the expansion element, the expandable material is extruded. In one exemplary refinement, multiple layers of expandable material are co-extruded.

[0052] Using an extruder process to form the expanded element has the advantage that no further steps such as heating and re-pressing of the different layers are required because the liquid material is combined into one unit during the extrusion process.

[0053] In one exemplary embodiment, the expandable material is an epoxy-based or rubber-based compound.

[0054] In an exemplary embodiment, the expandable material is a thermosetting material. In an exemplary refinement, the expandable material is configured such that it cures at a temperature of 130°C to 200°C.

[0055] In a first exemplary variant embodiment, the expandable material has an expansion ratio of 50% to 800%, preferably 100% to 500%, preferably 100% to 300%.

[0056] In a second alternative embodiment, the expandable material has an expansion ratio of 1000% to 3000%, preferably 1000% to 2500%, preferably 1000% to 2000%.

[0057] Exemplary expandable materials that can be used for the expansion elements presented herein are available under the trade names and get.

[0058] Details and advantages of the invention are described below on the basis of exemplary embodiments and with reference to schematic drawings. Description of the drawings:

[0059] Figures 1a to 1c A schematic diagram of an expansion element is shown;

[0060] Figure 2a and 2b a schematic diagram showing an expansion element in a cavity of a structural element; and

[0061] Figure 3 Schematic cross-sections of expanded expansion elements from a series of experiments in Table 1 are shown.

[0062] Figures 1a to 1c 1 shows different embodiments of expansion elements 1. Here, the expansion elements 1 are each shown in cross-section. Each expansion element 1 comprises an expandable material 2 and one or more planar fabrics 3. The total thickness 7 of the expansion element 1 is divided into individual layers by the planar fabrics 3, wherein each layer has a layer thickness 6. In all three embodiments, the minimum layer thickness 6 of the expansion element 1 is respectively designed so that it is at least 10% of the total thickness 7 of the expansion element 1.

[0063] In the three exemplary embodiments shown, the two-dimensional fabric 3 is respectively arranged symmetrically in the expansion element 1. However, in an alternative exemplary embodiment not shown, the two-dimensional fabric 3 can also be arranged asymmetrically.

[0064] exist Figure 2a and 2b In the embodiment, the expansion element 1 is arranged in the cavity 5 of the structural element 4 . Figure 2a Here the expansion element 1 is shown in the unexpanded state. Figure 2bThe same expansion element 1 ′ is shown in the expanded state.

[0065] It can be seen in this illustration that by arranging the flat fabric 3 between the expansion material layers 2, an increased expansion in a direction perpendicular to the flat fabric 3 is achieved, so that a smaller expansion element 1 can be used to close a gap between two substantially opposite structural elements.

[0066] exist Figure 2b It is evident that the expanded material 2', especially near the planar fabric 3 and near the structural element 4, expands less in the direction along the plane of the planar fabric 3 than if it were not connected to the planar fabric 3 or the structural element 4. This effect leads to an increased expansion in the direction perpendicular to the plane of the planar fabric 3.

[0067] Table 1 below represents an exemplary series of experiments with exemplary expansion elements. In these experiments, different expandable materials as well as different planar fabrics were used (as well as a comparative experiment using aluminum foil instead of planar fabric).

[0068] Applied as expandable material -604 (denoted as SR-604) and -235 (indicated as SB-235).

[0069] As the planar fabric, a polyester mesh, a glass fiber fabric, and a carbon fiber fabric were used. Here, an experiment using one planar fabric, an experiment using two planar fabrics, and a comparative experiment without a planar fabric were performed.

[0070] In addition, an experiment was conducted using aluminum foil instead of the flat fabric (sample R1a).

[0071] Table 1

[0072]

[0073] Firstly, it is apparent from this series of experiments that the planar fabric has a significant effect on the amount of height gain when the inflatable element is inflated.

[0074] Furthermore, the planar fabric was found to produce a greater height increase than the foil. The comparative experiment using aluminum foil had a height increase of 12% relative to the reference without the planar fabric, while all experiments using the planar fabric produced a height increase of at least 15%.

[0075] The results of the comparative experiments using aluminum foil can also be confirmed by WO 2011 / 109699 A1 mentioned at the beginning of this article. In Table 2 thereof, reinforced foils are used in four examples A to D, and the following percentage values ​​of the height increase compared to the reference example are found: Example A -3%, Example B +8%, Example C +12%, and Example D +14%.

[0076] Furthermore, it is clear from this experimental series that the greater the number of planar fabrics used, the greater the expansion perpendicular to the plane of the planar fabrics (as can be seen from the height increase in the table). For example, when two planar fabrics are used, the expansion in this direction is greater than when one planar fabric is used, and when one planar fabric is used, the expansion obtained in the desired direction is greater than in the reference example without a planar fabric.

[0077] Figure 3 Three exemplary cross sections from the experimental setup shown in Table 1 are depicted. Figure 3 The three lowest experiments (samples BR, B1p and B2p) are shown according to the experimental setup of Table 1. In this illustration of the cross-section of the resulting sample, the effect of the planar fabric 3 in improving the expansion in the direction perpendicular to the planar fabric 3 is also evident.

[0078] exist Figure 3 In the drawing, the position of the planar fabric 3 (in the exemplary embodiment a polyester mesh) is indicated by dashed lines, since the fabric is not visible due to scale and contrast.

[0079] Reference numerals list

[0080] 1- Expansion element in unexpanded state

[0081] 1'-Expansion element in expanded state

[0082] 2-Expandable materials

[0083] 2'-Expanded material

[0084] 3- Flat fabric

[0085] 4- Structural elements

[0086] 5- Cavity

[0087] 6- Layer Thickness

[0088] 7-Total thickness

Claims

1. Use of a flat fabric (3) for the controlled expansion of an expansion element (1) on a structural element (4) in a vehicle body, wherein the flat fabric (3) is covered on both sides with an expandable material (2), It is characterized in that The planar fabric (3) has a mesh size of 1 mm to 10 mm, and the expansion element (1) expands at least 15% in a direction perpendicular to the planar fabric (3) compared to the expansion element (1) without the planar fabric (3).

2. Use of a two-dimensional fabric (3) according to claim 1, wherein the two-dimensional fabric (3) is a net.

3. Use of the planar fabric (3) according to claim 1 or 2, wherein the weight per unit area of ​​the planar fabric (3) is 5 to 500 g / m 2 .

4. Use of the planar fabric (3) according to claim 1 or 2, wherein the planar fabric has a thickness of 10 μm to 1000 μm.

5. Use of a planar fabric (3) according to claim 1 or 2, wherein the fibers of the planar fabric (3) are oriented in multiple directions.

6. Use of the planar fabric (3) according to claim 1 or 2, wherein the planar fabric (3) does not substantially affect the tensile strength of the expansion element (1') in the cured state.

7. Use of a two-dimensional fabric (3) according to claim 1 or 2, wherein when the swellable material (2) is cured, crosslinks are formed which penetrate the two-dimensional fabric (3) through the swellable material (2').

8. Use of the planar fabric (3) according to claim 1 or 2, wherein the planar fabric (3) comprises at least one or more of the following materials: glass fibers, carbon fibers or polymer fibers.

9. Use of a flat textile (3) according to claim 8, wherein the polymer fibers are polyester fibers.

10. Use of a two-dimensional fabric (3) as claimed in claim 1 or 2, wherein two to five two-dimensional fabrics are used.

11. A method for connecting two structural elements (4) of a vehicle body using an expansion element (1), the method comprising the following steps: Providing an expandable material (2); Providing a planar fabric (3), wherein the planar fabric (3) has a mesh size of 1 mm to 10 mm; forming an expansion element (1) comprising an expandable material (2) and a planar fabric (3), wherein the planar fabric (3) is covered on both sides by the expandable material (2); and The expansion element (1) is expanded, wherein the expansion of the expansion element (1) in a direction perpendicular to the planar fabric (3) is at least 15% greater than the expansion element (1) without the planar fabric (3).

12. The method of claim 11, wherein the method comprises the following additional steps: The expansion element (1) is adhered to one of the structural elements (4).

13. The method according to claim 12, wherein the expandable material (2) is viscous at room temperature, and wherein the expansion element (1) is separated from the carrier element before being arranged on the structural element (4), and wherein the expansion element (1) has a handling foil on one side.

14. The method according to claim 12, wherein the expandable material (2) is not viscous at room temperature and wherein the expansion element (1) has an adhesive film on one side for adhering to the structural element (4).

15. Method according to any one of claims 11 to 14, wherein when forming the expansion element (1), the expandable material (2) is extruded.

16. Method according to any one of claims 11 to 14, wherein the expandable material (2) is co-extruded when forming the expansion element (1).

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