Barrier element and system for blocking a structural element

Abstract

An expandable material, that is pumpable and / or extrudable, is used to at least partially block a cross-section of a cavity as a barrier element, in particular a cavity in a motor vehicle, upon expansion. No additional carrier is used to block the cross-section of the cavity. Even in absence of a carrier the expandable material at least partially blocks the cross-section of the cavity in an expanded state. This enables a sustainable blocking of the cavity cross-section as the absence of a carrier means that no additional material is to be applied.

Description

[0001] BARRIER ELEMENT AND SYSTEM FOR BLOCKING A STRUCTURAL ELEMENT

[0002] Technical field

[0003] The invention relates to barrier element for blocking a cavity at least partially.

[0004] Prior art

[0005] Within Automotive industry one solution used to improve acoustic performance is to use PUR-foam that is injected after the E-coat and paint ovens. The foam is intended to completely fill a specific area and is either acoustic foams with high absorption or more rigid foam that stiffen the section.

[0006] At injection foam is very liquid and therefore difficult to control. Due to tolerances on both injected volume, expansion rate and exactly how foam is placed when it starts to expand the result can be quite different from one vehicle to another. Often the targeted areas are close to holes that cannot be covered by the foam or where the complete inside of the pillar must be available to assembly of external components like cables or cameras.

[0007] Current solution is therefore to use Foam Blockers to stop or reduce the expansion. These foam blockers can be a metal piece partly blocking the cavity or more commonly by a plastic carrier. A common factor is that the cavities must not be 100% closed to fulfill their function, just sealing a major part of the cavity might be enough.

[0008] Summary of the invention

[0009] It is an object of the present invention to provide a new application of an expandable material, a barrier element for at least partially blocking a cavity and a method to reinforce a cavity as well as a system for blocking a structural element.

[0010] It has been found that, surprisingly, this object is achieved by using an expandable material in combination with a curable material without the use of a carrier element.

[0011] Ways of executing the invention

[0012] An expandable material that is extrudable and / or pumpable is used to at least partially block a cross-section of a cavity as a barrier element, in particular a cavity in a motor vehicle, upon expansion. No additional carrier is used to block the cross section of the cavity. In other words, even in absence of a carrier the expandable material at least partially blocks the cross-section of the cavity in an expanded state. This enables a sustainable blocking of the cavity cross- section as the absence of a carrier means that no additional material is to be applied. Carrier plates usually comprise a nylon material.

[0013] The absence of a carrier implies that the expandable material is directly applied to a wall of the cavity, in particular a structural element.

[0014] The term "pumpable" of the expandable material of the present application is understood such, that at ambient temperature (20°C) or elevated temperatures below the expansion initiation temperature the expandable material has a viscosity which is suitable for pumping and preferably has a paste-like viscosity. The viscosity of the pumpable expandable material is usually in the range of 50 to 500 Pa s and preferably 100 to 300 Pa s, when measured by means of a rheometer with heatable plate (MCR 301, AntonPaar) (gap 1000 pm, measuring plate diameter: 25 mm (plate / plate), deformation 0.01-10 % at 5 Hz, temperature: 20°C). When the viscosity is lower than 50 Pa s, dripping can more easily occur, and the shape cannot sufficiently be maintained during processing. If on the other hand, the viscosity exceeds 500 Pa s, the workability of the material is greatly reduced.

[0015] In the context of the present application, it is important to note that the term "pumpable" does not refer to an inflatable material such as a balloon. Rather, the pumpable expandable material described herein may be a viscous, paste-like substance that can be applied through pumping equipment. Unlike an inflatable balloon that expands by filling with air or gas, this pumpable material may expand through chemical or physical processes when exposed to certain conditions, such as heat. The expansion of the material may result in a solid or semi-solid barrier element, rather than an air-filled structure. This distinction highlights the unique properties and applications of the pumpable expandable material in forming barrier elements within cavities.

[0016] For example, EP3281970 discloses a pumpable expandable material based on combinations of a liquid epoxy resin and a polyvinyl chloride resin and / or an acrylic resin powder. These pumpable materials provide the advantage that they can be applied as needed using conventional injection equipment and can be expanded to provide foam with good physical strength, high expansion and good adhesion on oiled metal substrates.

[0017] In addition to the pumpable properties described above, the expandable material may alternatively be extrudable. The term "extrudable" in the context of the present application refers to the ability of the expandable material to be forced through an opening or die to form a continuous shape or profile at temperatures below the expansion initiation temperature (ambient temperature (20°C) or elevated temperatures). The extrudable expandable material may have a consistency that allows it to maintain its shape after extrusion while remaining sufficiently flowable to be processed through extrusion equipment. The extrudable expandable material may have a viscosity that is suitable for extrusion processes, typically in the range of 200 to 800 Pa-s, and preferably 300 to 600 Pa-s, when measured by means of a rheometer with heatable plate (MCR 301, AntonPaar) under the same conditions as described for pumpable materials. When the viscosity is lower than 200 Pa-s for extrusion applications, the material may not maintain sufficient structural integrity during the extrusion process. If the viscosity exceeds 800 Pa-s, the material may become too stiff for efficient extrusion through standard equipment.

[0018] The extrudable expandable material may be applied using conventional extrusion equipment, such as pneumatic or electric extrusion guns, cartridge-based dispensing systems, or automated extrusion robots. This application method may provide advantages in terms of precise placement control, consistent bead dimensions, and the ability to create complex geometric patterns within the cavity. The extruded material may form continuous or discontinuous beads, depending on the application requirements and the desired blocking characteristics of the barrier element.

[0019] Upon expansion, the extrudable material may exhibit similar expansion characteristics to the pumpable variant, achieving expansion rates of at least 200%, preferably at least 500%, when subjected to appropriate activation conditions such as elevated temperatures. The expanded extrudable material may provide equivalent or superior blocking performance compared to pumpable alternatives, while offering enhanced control over the initial placement geometry and distribution within the cavity.

[0020] In an embodiment, the expandable material may have specific contact area arrangements that enhance its blocking performance. The expandable material may comprise a first contact area and a second contact area, wherein the first contact area is arranged to contact the cavity wall while the second contact area is positioned opposite to the first contact area and does not contact the cavity wall. This asymmetric contact arrangement may allow for efficient material usage while maintaining effective blocking performance. The distance between the second contact area and the cavity wall may be maintained at 2 mm to 6 mm, providing optimal expansion space and blocking characteristics.

[0021] In an embodiment, the cavity is arranged in a structural element.

[0022] In an embodiment, the expandable material may be applied using robotic application systems. Robotic application may provide enhanced precision in material placement, consistent bead formation, and improved repeatability compared to manual application methods. The robotic system may be programmed to apply the expandable material in specific patterns, including non-continuous arrangements with predetermined gaps between beads. This automated approach may be particularly advantageous in automotive manufacturing environments where high precision and consistency are required. In an embodiment, the cavity is substantially blocked before filling the cavity with a curable material, in particular a curable reinforcing and / or acoustic material. The curable material can be a PU (Polyurethan) material to reinforce or acoustically improve the cavity after curing. The curable material can cure at room temperature through a chemical reaction without significant thermal activation. In other words, the expanded material is used to block the spread of the curable material. This enables a precise and flexible positioning of the curable material in the cavity.

[0023] In an embodiment, the expandable material may be configured to achieve enhanced expansion rates of at least 500%, or in some cases at least 800%, when subjected to appropriate activation conditions. These higher expansion rates may provide superior blocking performance and may enable the use of smaller initial material volumes while achieving effective cavity blocking. The enhanced expansion may be particularly beneficial in applications where space constraints limit the initial material placement volume.

[0024] In an embodiment, the positioning of expandable material in the cavity is adjusted according to the needs of the assembly space in the cavity. This means that according to required reinforcement and / or acoustic properties, the position of the expandable material and therefore the barrier element in the cavity can be adjusted without additional construction effort, as no carrier has to be produced and transported. No carrier has to be adapted to the shape of the assembly space. The cavity does not need to be provided with fastening means to fasten a carrier. In the expandable state the cavity is in fluid communication. In other words, in the expandable state the cavity is not substantially blocked. This means that in the expandable state, there is a significant opening in the cavity not filled, neither with expandable material nor with a carrier.

[0025] In an embodiment, the positioning of openings in the structural element may be specifically configured to optimize material application and cavity filling. The first opening, through which the expandable material is applied, and the second opening, through which the curable material is introduced, may be positioned at different locations on the structural element. This differential positioning may enable better control over material flow and distribution within the cavity. The openings may be arranged in different walls of the cavity to facilitate optimal access and material placement.

[0026] A further aspect of the invention concerns the barrier element itself, in particular a barrier element for at least partially block a cross-section of a cavity, in particular in a structural element, in particular in a vehicle body. The barrier element comprises an expandable material, in particular a pumpable and expandable material. The barrier element is equipped to block a cavity. In particular the barrier element is equipped to block a cavity against substantial inflow of a curable material in an expanded state. The barrier element is free of a carrier element. In an expandable state the barrier element, in particular the expandable material, is pumpable. This leads to a very sustainable barrier element, as no additional carrier is needed in the assembly space.

[0027] In an embodiment, the expandable material may comprise specific material compositions that enhance its performance characteristics. The expandable material may comprise a combination of a liquid epoxy resin and at least one of a polyvinyl chloride resin and an acrylic resin powder. This combination may provide optimal viscosity characteristics for both pumpable and extrudable applications while maintaining excellent expansion properties and adhesion to cavity surfaces. The material composition may be tailored to achieve specific viscosity ranges suitable for different application methods.

[0028] In an embodiment, the cavity resp. the structural element comprises a first and a second contact area. The first contact area is arranged opposite to the second contact area. The expandable material contacts the cavity resp. the structural element at a first contact area and a second contact area free of contact with the expandable material. Meaning, that the second contact area of the cavity resp. the structural element is free of any contact with the expandable material and does not contact resp. touch it. In other words, the expandable material is arranged in the cavity such, that there is a distance between the second contact area of the cavity resp. the structural element and the expandable material.

[0029] In an embodiment, the expandable material in the expandable state does not touch a cavity wall in a circumferential manner. This means that the expandable material does not contact the entire circumference of the inner wall of the cavity. In other words, a portion of the cavity wall opposite to the expandable material remains free of contact with the expandable material. This configuration enables a further reduction in material usage, resulting in a more sustainable and cost-effective barrier element while maintaining effective blocking performance.

[0030] In an embodiment, the expandable material is applied to the inner wall of the cavity in a non- continuous manner. This leads to a reduced material usage. The gap between beads of pumped, expandable material is free of additional material. This enables a reliable and costefficient blocking of the cavity cross-section.

[0031] In an embodiment, the expandable material is pumpable at a temperature of less than 80°C and / or wherein the expandable material is expanded at a temperature of more than 100°C. This enables a subsequent pumping and controlled expansion at different temperatures.

[0032] In an embodiment, the barrier element is equipped to reduce the airborne noise in the cavity by at least 20%, in particular at least 35%, in particular at least 45%, in particular compared to a barrier element made of steel or nylon, similar to the one shown in Fig. 6a. The barrier element can by equipped to the structure born noise in the cavity by 15 %, in particular 20%, in particular at least 35%, in particular compared to a barrier element made of steel or nylon, similarto the one shown in Fig. 7a. The noise reduction forthe airborne noise can be achieved at the side of the cavity facing the barrier element. The noise reduction of the structure borne noise can be achieved on the side of the cavity facing the curable or cured material.

[0033] In an embodiment, the barrier element may be configured to achieve enhanced noise reduction performance. The barrier element may be equipped to reduce airborne noise in the cavity by at least 45%, and in some cases up to 60% or more, compared to conventional barrier elements made of steel or nylon. Additionally, the barrier element may reduce structure-borne noise by at least 35%, and in some cases up to 50% or more. This enhanced acoustic performance may be attributed to the specific material properties and expansion characteristics of the expandable material, which may provide superior damping and absorption compared to rigid carrier-based systems.

[0034] In an embodiment, the expanded barrier element may be configured to block a substantial portion of the cavity cross-section, typically at least 90% of the cross-sectional area. This high blocking percentage may ensure effective containment of the curable material while maintaining the desired cavity reinforcement characteristics. The blocking percentage may be achieved through appropriate selection of expandable material volume, expansion rate, and placement pattern within the cavity.

[0035] Another aspect of the invention is focused on a method to reinforce a cavity.

[0036] The method to reinforce and / or damp a cavity, in particular in motor vehicle, the method comprises the steps of: a. applying an expandable material in the cavity in the cavity, in particular to the crosssection of the cavity; b. expanding the expandable material in the cavity as a barrier element and thereby blocking the cavity at least partially in particular at least 90% of the cavity cross-section, by the expanded material to build a barrier element, in particular a barrier element as described in the present text; c. filling the cavity with a curable material, in particular a curable reinforcing material, up to the barrier element in the expanded state, and curing the curable material, wherein the cavity is free of any carrier supporting the expandable material. In particular the cavity is free of any carrier at the cross-section of the cavity. The expandable material is pumpable and / or extrudable, and wherein the pumpable expandable material having a viscosity in the range of 50 to 500 Pa-s when measured by means of a rheometer with heatable plate at 20°C.

[0037] This makes it possible to efficiently and flexibly place a barrier element in the cavity without the need of producing and transporting an additional carrier element.

[0038] In an embodiment, the method may include specific application parameters that enhance the effectiveness of the barrier element formation. The expandable material may be applied at controlled viscosity ranges, with pumpable materials having viscosity in the range of 50 to 500 Pa-s , in particular 100 to 300 Pa-s, and extrudable materials having viscosity in the range of 300 to 600 Pa-s when measured at 20°C. The application may be performed in a non- continuous manner, forming discrete beads with predetermined gaps between them, which may optimize material usage while maintaining effective blocking performance.

[0039] In an embodiment, the expandable material is applied by pumping or extruding the expandable material, in particular in form of one or more beads, into the cavity. This application method provides precise control over material placement and distribution within the cavity structure. The pumped or extruded, in particular beaded, application pattern allows for optimal expansion characteristics while minimizing material usage.

[0040] When applied as discrete beads, the expandable material can maintain its position during the pre-expansion phase and subsequently expand in a controlled manner to effectively block the cavity cross-section. The bead formation may be continuous or discontinuous depending on the specific blocking requirements and cavity geometry. The diameter and length of the beads can be adjusted according to the cavity dimensions and the desired blocking percentage.

[0041] In an embodiment, the cavity comprises at least a first opening and a second opening. The openings are connecting the inner space (also called inside) of the cavity with the space surrounding the cavity (also called outside). The expandable material is applied into the cavity through the first opening and the curable material, in particular a curable reinforcing and / or acoustic material, is filled into the cavity through the second opening. This makes it possible that the expandable material and therefore the barrier element can be applied next to the curable material, enabling the blocking of the cavity and a stopping of the curable material.

[0042] In an embodiment, the first opening is at a different position than the second opening.

[0043] In an embodiment, at least one of the openings is arranged in a wall of cavity. The wall is delimiting / surrounding the cavity.

[0044] In an embodiment, the first opening is at a different position than the second opening. In an embodiment, the first opening and / or the second opening has a circular shape. This supports the stress resistance of the cavity.

[0045] In an embodiment, the openings in the structural element may have specific geometric configurations that facilitate optimal material application. The first opening and the second opening may each have a circular shape, which may provide structural integrity and facilitate sealing after material application. The circular configuration may also enable the use of standard application equipment and may reduce stress concentrations in the structural element. The openings may be positioned in different walls of the cavity to enable independent control of expandable material and curable material introduction.

[0046] In an embodiment, the expandable material comprises a first expandable material and a second expandable material; wherein the method comprises the step of:

[0047] • providing a first expandable material;

[0048] • arranging the first expandable material on a first part of the structural element;

[0049] • arranging a second expandable material on a second part of the structural element;

[0050] • joining the first part and the second part of the structural element in order to form the structural element with the cavity, wherein first expandable material and the second expandable material are arranged in the cavity between the two parts of the structural element; and

[0051] • expanding the first expandable material and the second expandable material, as a result of which a cross section of the cavity is at least partially blocked by a first expanded material and the second expanded material.

[0052] In an embodiment, the first expandable material and the second expandable material are different from each other. Different meaning that the expandable materials comprise a different composition.

[0053] In another embodiment, the first expandable material and the second expandable material are essentially identical. Identical means that the composition of the first expandable material and the second expandable material are essentially the same. In other words, the mechanical and chemical properties of the first expandable material and the second expandable material are essentially the same.

[0054] Another aspect of the invention concerns a system for blocking a cavity. The system for blocking a structural element in a motor vehicle, the system comprising a structural element wherein the structural element forms the cavity. The system further comprising an expandable material which is arranged on the structural element by pumping. The expandable material is formed and arranged such that the expandable material at least partially blocks the cross section of the cavity in an expanded state and forms a barrier element in the expanded state, in particular a barrier element as described in this text. The system is free of a carrier. This makes it possible to sustainably and cost efficiently block the cavity.

[0055] In an embodiment, the system may incorporate advanced application methods that enhance precision and consistency. The expandable material may be applied using robotic systems that provide precise control over material placement, bead dimensions, and application patterns. The robotic application may enable the formation of complex geometric arrangements within the cavity, including non-continuous patterns with specific gap dimensions between material beads. This automated approach may be particularly beneficial in high-volume manufacturing environments where consistency and repeatability are critical.

[0056] In an embodiment, a structural element comprises a first component and a second component, wherein the components are joined together at a first joining point and at a second joining point. As already described before, the structural element forms the cavity. The expandable material contacts the structural element at the first joining point and / or at the second joining point. This enables a simplified assembly of the system.

[0057] In an embodiment, the expandable material, has, in each case proceeding from the joining points, an extent along the second component of the structural element of at least 10 mm. This enables a reliable connection and sealing of the cavity.

[0058] In an embodiment, the system may be configured with specific dimensional relationships that optimize blocking performance. The distance between the expanded material and the structural element at non-contact areas may be maintained within a range of 2 mm to 6 mm, providing optimal expansion space while ensuring effective blocking. The expandable material may be arranged to contact the structural element at specific contact areas while maintaining predetermined distances at opposite areas, creating an asymmetric contact pattern that may enhance both material efficiency and blocking effectiveness.

[0059] In an embodiment, the second expandable material forms a continuous element between the joining points.

[0060] In an embodiment, the structural element comprises at least a first opening and a second opening. The openings are connecting the inside of the structural element with outside of the structural element. The expandable material is applied into the structural element through the first opening. The curable material, in particular a curable reinforcing and / or acoustic material, is filled into the structural element through the second opening. This enables to provide a system with the expandable material arranged next to the curable material. In an embodiment, the first opening and / or the second opening have a circular shape. This increases the stress resistance of the system.

[0061] In an embodiment, the expandable material is in an expandable state and is configured, and arranged, in such a way that, after the material has been expanded, the expanded material at least partially blocks / fills a cross section of the structural element.

[0062] In an embodiment, the expandable material is a flowable, unformed material prior to activation / expansion. This enables the transportation of the expandable material as a bulk material, which reduces packaging.

[0063] In an embodiment, the expandable material is arranged in the form of one or more beads on the structural element. In an embodiment, the at least one bead has a diameter of 2 to 20 mm and / or wherein the at least one bead has a length of at least 10 mm.

[0064] In an embodiment, the expandable material is formed as a continuous element or as a plurality of non-continuous elements.

[0065] In an embodiment, a distance between the expanded material (expandable material in the expanded state) and the structural element is 2 mm to 6 mm.

[0066] In an embodiment, the expandable material comprises a first and a second contact area. The first contact area is arranged opposite to the second contact area. The expandable material contacts the cavity resp. the structural element at a first contact area and a second contact area does not contact the cavity resp. the structural element. Meaning, that the second contact area of the expandable material is free of any contact with the cavity resp. the structural element. In other words, the expandable material is arranged in the cavity such, that there is a distance resp. gap between the second contact area and the cavity resp. the structural element.

[0067] In an embodiment, the barrier element and the curable material contact each other. In other words, the barrier element and the curable material are arranged adjacent to each other in a way that they tough each other.

[0068] In an embodiment, the expandable material has an expansion rate of at least 200% or of at least 300% or of at least 400% or of at least 500% or of at least 800%. The expansion rate of the expandable material is measured as the percentage increase in volume from the unexpanded state to the fully expanded state. To determine this rate, a sample of the unexpanded material with a known initial volume (V is subjected tothe expansion conditions (typically heating to the specified expansion temperature) until complete expansion occurs. The final volume (V2) of the expanded material is then measured. The expansion rate is calculated using the formula: Expansion Rate (%) = [(V2- V^ / V x 100. The tested material was first shaped into form of strips having dimensions 25 x 25 x 2 mm (length x width x thickness) and then baked at 160°C, 180°C, 200°C, and 220°Cfor 20 or 25 minutes. The volume expansion in percentage was then calculated as: (\ / after - \ / before) / \ / before. The volumes of the strips before and after the baking process are determined based on density measurements. The densities of the strips are measured according to DIN EN ISO 1183 standard using the water immersion method (Archimedes principle) in deionized water and a precision balance to measure the mass.

[0069] Such an expandable material is described, by way of example, in European patent application EP 3 281 970 Al, and is herewith incorporated by reference.

[0070] An example of such an expandable, pumpable material is an adhesive that can be obtained under the trade name Sikaseal®. An example of an expandable adhesive which can be extruded can be obtained under the name Si ka Baffle® 455.

[0071] In one exemplary embodiment, the expandable, pumpable material is arranged in the cavity in the form of a bead or a plurality of beads.

[0072] In one exemplary embodiment, the expandable, pumpable material is arranged in the cavity by a robot.

[0073] In one exemplary embodiment, at least one bead has a diameter of from 2 to 20 mm or of from 4 to 18 mm or of from 6 to 16 mm.

[0074] In one exemplary embodiment, the at least one bead has a length of at least 10 mm or of at least 20 mm or of at least 30 mm or of at least 50 mm or of at least 100 mm.

[0075] In an embodiment, the expanded barrier element blocks at least 50%, in particular at least 75%, in particular at least 80%, in particular at least 90%, in particular 100%, of the crosssection of the cavity of the structural element.

[0076] The individual features of the described embodiments and features, in particular of the use of the barrier element, the barrier element as such and the method as well as the system, can be combined with each other without limitations.

[0077] Details and advantages of the invention will be described below on the basis of exemplary embodiments and with reference to schematic drawings, in which:

[0078] Fig. 1 shows a cavity of a structural element with two barrier elements blocking a cross-section of the cavity with a cured material;

[0079] Fig. 2 shows a similar embodiment as Fig.l with one cross-section of the cavity being only partially closed and where the position on the lower barrier element has been moved to increase the volume of a targeted area; Fig. 3 shows a structural element with two openings to apply an expandable material and a curable material;

[0080] Figs. 4a & 4b show a sectional view of a structural element with an expandable material arranged in the cavity respectively the expanded barrier element with the cured material;

[0081] Figs. 5a-c showthe cavity (a), with the expandable material (b) and the expanded barrier element.

[0082] Figs. 6a&6b illustrate the properties of the barrier element in relation to airborne noise; and

[0083] Figs. 7a&7b illustrate the properties of the barrier element in relation to structure borne noise; and

[0084] Figures 1 and 2 show a cavity 30 of a structural element 3 with two barrier element Is each blocking a cross-section of the cavity 30 against a cured martial. The barrier element 1 is carrier free expanded material 10 that blocks a cross-section of the cavity 30 of the structural element 3. A third cross-section of the cavity 30 remains free from a barrier element 1.

[0085] The curable material 40 can be a two-component composition, in particular curing at room temperature. The curable material 40 can be a reinforcing and / or acoustic material.

[0086] The third cross-section can be covered with the curable material 40 even without a barrier element 1 (Fig.l). In certain situations, the area 19 covered by the curable material 40 at the third cross-section must be kept free from curable material 40. This might be the case if an additional element is to be installed in this area. In order to keep the area of the third crosssection free of curable material 40, one barrier element 1 might not completely block the cross-section but allows a portion of the curable material 40 to pass through the crosssection. In other words, a part of the curable material 40 partially leaks through the crosssection at the position of the barrier element 1. Furthermore, the position on the lower barrier element has been moved to increase the volume of a targeted area. This enables to stop the curable material 40 before the critical area 19 to be free of curable material 40 (Fig.2).

[0087] It is also possible to easily adapt the position of the barrier element 1, due to the leak of repositioning any carrier. The position of the barrier element 1 can be adjusted by repositioning an expandable material, that is pumpable and / or extrudable, in the cavity 30 and expand it. Accordingly, the position of the expanded barrier element 1 is adjusted influencing the stop of the curable material 40. This also enables the adjustment and optimization of the filling of the cavity 30 with the curable material 40 and leaving the critical area 19 free from curable material 40.

[0088] Figure 3 shows a structural element 3 with two openings. The two holes enable the application of an expandable material 10 and a curable material 40 into the cavity 30 of the structural element 3. The expandable material 10 can be applied through the first opening 31 and the curable material 40 can be applied through the second opening 32. The structural element 3 can be a single-piece element or can comprise several parts joint 35ed together, in particular along a longitudinal axis of the structural element 3.

[0089] Figs. 4a & 4b show a sectional view of a structural element 3. Fig. 4a depicts the expandable material 10 arranged in the cavity 30. Fig.4b shows the expanded barrier element 1 with the cured material 41. The expandable material 10 is arranged at a position opposite the first opening 31 in the structural element 3. Upon expansion the barrier element 1 blocks the cross-section of the cavity 30 resp. the structural element 3. In a next step the curable material 40 is injected into the cavity 30 through the second opening 32 and cures after injection in the cavity 30.

[0090] The curable material 40 is injected until it contacts the barrier element 1, resulting in a contacting bridge between the barrier element 1 and the cured material 41. This enables a dissipation of noise through the contacting bridge.

[0091] Figs. 5a-c show the empty cavity 30 (a), the cavity 30 with the expandable material 10 (b) and the cavity 30 with the expanded barrier element 1. The cavity 30 is free of any carrier (fig. 5a). The expandable material 10 is applied to one side of the cross-section of the cavity 30 (fig. 5b). The opposing side of the cavity 30 is free of any expandable material 10. Upon expansion the cross-section of the cavity 30 is partially blocked (fig. 5c). In embodiments, the joint between the first part of the structural element and the second part of the structural element can be contacted by the expanded material.

[0092] Figs. 6a&6b illustrate the properties of the barrier element 1 in relation to airborne noise NA. Fig.6a shows the prior art PA situation, where a solid carrier element C made of nylon is used as a barrier element 1 to block the cross-section of the cavity 30 against the cured material 41. The airborne noise originating from a source NA(S) travels through the cavity 30. The airborne noise reaches the carrier element at a side facing away from the cured material 41. The airborne noise gets reflected. The reflected airborne noise NA(R) is at least 95% of the airborne noise originating from the source. This means that the prior art PA barrier element Is are not equipped to significantly reduce the airborne noise within the cavity 30.

[0093] In contrast to that, Fig.6b shows the situation according to the present invention. The airborne noise originating from a source NA(S) travels through the cavity 30. The airborne noise reaches the expanded barrier element 1 at a side facing away from the cured material 41. A portion of the airborne noise can be dissipated NA(D) by barrier element 1 in the expanded state. A further part of the airborne noise can enter NA(E) the cured material 41 via the expanded barrier element 1 and gets dissipated NA(D-cure) by the cured material 41. Only a fraction of the airborne noise originating from the source is reflected NA(R) back in the direction of the source. A significant part of the airborne noise is dissipated by either the expanded barrier element or the cured material 41, in particular after transmission from the expanded barrier element 1 to the cured material 41. The barrier element 1 is equipped to reduce the airborne noise by at least 20%, in particular at least 35%, in the cavity 30.

[0094] A further example shown in Fig. 7a&7b illustrates the properties of the barrier element 1 in relation to structure borne noise NS. Fig.7a shows the prior art PA situation, where a solid carrier element C made of nylon is used as a barrier element 1 to block the cross-section of the cavity 30 against the cured material 41. The structure borne noise does not significantly interfere with solid carrier but is mostly entering the into the cured material 41, where it is partially dissipated NS(D-cure) and transmitted NS(T) partially at the side opposite to the carrier element.

[0095] In contrast to that Fig.7b shows the situation according to the present invention. The structure borne noise originating from a source NS(S) travels through the structural element 3. The structure borne noise reaches the expanded barrier element 1 at a side facing away from the cured material 41. A portion of the structure borne noise can be dissipated NS(D) by the barrier element 1 in the expanded state. A further portion of the airborne structure borne noise can enter NS(E) the cured material 41 via the expanded barrier element 1 and gets dissipated NS(D-cure) by the cured material 41. Only a fraction of the structure borne noise originating from the source is transmitted NS(T) through the expanded barrier element 1 and the cured material 41. A significant part of the structure borne noise is dissipated by either the expanded barrier element or the cured material 41, in particular after transmission from the expanded barrier element 1 to the cured material 41. The barrier element 1 is equipped to reduce the structure borne noise by at least 15%, in particular at least 20%, in the cavity 30 resp. the structural element 3. Reference signs

[0096] I barrier element

[0097] 10 expandable material

[0098] II expanded material

[0099] 3 structural element

[0100] 30 cavity

[0101] 31 first opening

[0102] 32 second opening

[0103] 33 first part of the structural element

[0104] 34 second part of the structural element

[0105] 35 joint

[0106] 40 curable material

[0107] 41 cured material

[0108] C carrier

[0109] PA prior art

[0110] NA air borne noise

[0111] NA(S) air borne noise originating from a source

[0112] N A(R) reflected air borne noise

[0113] NA(D) dissipated air borne noise by the barrier element in the expanded state

[0114] NA(E) entering air borne noise into the cured material

[0115] NA (D-cure) dissipated air borne noise by the cured material

[0116] NS structure borne noise

[0117] NS(S) structure borne noise originating from a source

[0118] NS( R) reflected structure borne noise

[0119] NS(D) dissipated structure borne noise by the barrier element in the expanded state

[0120] NS(E) entering structure borne noise into the cured material

[0121] NS (D-cure) dissipated structure borne noise by the cured material

[0122] NS(T) transmitted structure borne noise

Claims

Claims:

1. A use of an expandable material that is pumpable and / or extrudable to at least partially block a cross-section of a cavity as a barrier element, in particular a cavity in a motor vehicle, upon expansion; wherein no additional carrier is used to block the cross section of the cavity; wherein the expandable and pumpable material has a viscosity in the range of 50 to 500 Pa-s when measured by means of a rheometer with heatable plate at 20°C.

2. The use according to claim 1, wherein the cavity is substantially blocked before filling the cavity with a curable material, in particular a curable reinforcing and / or acoustic material.

3. The use according to claim 1 or 2, wherein the expandable material has an expansion rate of at least 500%.

4. The use according to any one of claims 1-3, wherein the expandable material in an expandable state does not touch a cavity wall in a circumferential manner such that a portion of the cavity wall opposite to the expandable material is free of the expandable material.

5. Barrier element for at least partially blocking a cross-section of a cavity, wherein the barrier element comprises an expandable material that is pumpable and / or extrudable, and wherein the pumpable expandable material has a viscosity in the range of 50 to 500 Pa-s when measured by means of a rheometer with heatable plate at 20°C; wherein the barrier element is equipped to block a cavity, in particular against substantial inflow of a curable material in an expanded state; wherein the barrier element is free of a carrier element; wherein the barrier element in an expandable state is pumpable and / or extrudable; wherein in the expandable state the cavity is in fluid communication.

6. Barrier element according to claim 5, wherein the expandable material has an expansion rate of at least 500%.

7. Barrier element according to any one of claims 5-6, wherein the expandable material in the expandable state does not touch a cavity wall in a circumferential manner.

8. Barrier element according to any one of claims 5-7, wherein the expandable material is applied to an inner wall of the cavity in a non-continuous manner with gaps between beads of the expandable material.

9. Barrier element according to any one of claims 5-8, wherein the expandable material is arranged in the form of one or more beads having a diameter of 2 to 20 mm and a length of at least 10 mm.

10. Barrier element according to any one of claims 5-9, wherein the expandable material is pumpable at a temperature of less than 80°C and / or wherein the expandable material is expanded at a temperature of more than 100°C.

11. Barrier element according to any one of claims 5-10, wherein the barrier element is equipped to reduce the airborne noise by at least 20%, in particular at least 35%, and / or the structure born noise by 15 %, in particular 20%, in the cavity compared to a barrier element made of steel or nylon.

12. Method to reinforce and / or damp a cavity, in particular in a motor vehicle, the method comprising the steps of: a. applying an expandable material in the cavity; b. expanding the expandable material in the cavity as a barrier element; c. blocking the cavity at least partially, in particular at least 90% of the cavity cross-section, by the expanded material to build a barrier element, in particular a barrier element according to one of claims 5-11;d. filling the cavity with a curable material, in particular a curable reinforcing and / or acoustic material, up to the barrier element in the expanded state, and curing the curable material; wherein the cavity is free of any carrier supporting the expandable material; and wherein the expandable material is pumpable and / or extrudable, and wherein the pumpable expandable material having a viscosity in the range of 50 to 500 Pa-s when measured by means of a rheometer with heatable plate at 20°C.

13. Method according to claim 12, wherein the expandable material is applied by pumping or extruding the expandable material in form one or more beads into the cavity.

14. Method according to any one of claims 12-13, wherein the cavity comprises at least a first opening and a second opening; wherein the openings are connecting an inside of the cavity with an outside of the cavity; wherein the expandable material is applied into the cavity through the first opening in particular by robotic application; and wherein the curable material, in particular a curable reinforcing and / or acoustic material, is filled into the cavity through the second opening.

15. Method according to any one of claims 12-14, wherein the first opening and / or the second opening has a circular shape and / or wherein the first opening and the second opening are arranged in different walls of the cavity.

16. Method according to any one of claims 12-15, wherein the expandable material is a flowable material prior to expansion.

17. Method according to any one of claims 12-16, wherein the expandable material comprises a combination of a liquid epoxy resin and at least one of a polyvinyl chloride resin and an acrylic resin powder.

18. System for blocking a structural element in a motor vehicle, the system comprising:• a structural element wherein the structural element forms a cavity;• an expandable material which is arranged on the structural element by pumping or extruding; wherein the expandable material is formed and arranged such that the expandable material at least partially blocks, in particular 90% of the cross section of the cavity, in an expanded state and forms a barrier element in the expanded state; wherein the system is free of a carrier. wherein the expandable material is pumpable and / or extrudable, and wherein the pumpable expandable material having a viscosity in the range of 50 to 500 Pa-s when measured by means of a rheometer with heatable plate at 20°C.

19. System according to claim 18, wherein the structural element comprises at least a first opening and a second opening; wherein the openings are connecting an inside of the structural element with an outside of the structural element; wherein the expandable material is applied into the structural element through the first opening wherein the curable material, in particular a curable reinforcing and / or acoustic material, is filled into the structural element through the second opening.

20. System according to claim 19, wherein the first opening and / or the second opening has a circular shape and / or wherein the first opening and the second opening are arranged in different walls of the cavity.

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