Patent Publication Number: US-2021163078-A1

Title: System for insulating a structural element

Description:
The invention relates to a system for insulating a structural element in a motor vehicle. It also relates to a method for insulating a structural element in a motor vehicle. 
     In many cases, components, such as for example bodies and/or frames of transportation and conveyance means, in particular of aquatic or terrestrial vehicles or of aircraft, have structures with cavities in order to make lightweight constructions possible. However, these cavities cause a wide variety of problems. Depending on the nature of the cavity, it has to be sealed in order to prevent the ingress of moisture and dirt, which can lead to corrosion of the components. It is often also desirable to substantially reinforce the cavities, and thus the component, but to retain the low weight. It is often also necessary for the cavities, and thus the components, to be stabilized in order for noises which would otherwise be transmitted along or through the cavity to be reduced. Many of these cavities have an irregular shape or a narrow extent, making it more difficult to seal, reinforce and insulate them properly. 
     In particular in automotive construction, but also in aircraft construction and boat building, sealing elements (baffles) are therefore used in order to seal and/or acoustically isolate cavities, or reinforcing elements (reinforcers) are used in order to reinforce cavities. 
       FIG. 1  schematically illustrates a body of an automobile. Here, the vehicle body  10  has various structures with cavities, such as for example pillars  14  and carriers or braces  12 . Such structural elements  12 ,  14  with cavities are usually sealed and/or reinforced, respectively, using sealing and/or reinforcing elements  16 . 
       FIGS. 2 a  and 2 b    schematically show a known concept for the sealing and/or reinforcing closure of openings or cavities in a motor vehicle. 
     Here,  FIG. 2 a    shows a device  16  prior to an expansion of an adhesive  13 .  FIG. 2 b    shows the same device  16  as a constituent part of the system  1  but after the adhesive  13  has been expanded, that is to say with the expanded adhesive  13 ′. 
     The device  16  is located in a cavity of a vehicle body structure, as is illustrated for example in  FIG. 1 . A portion of such a structural element  12 ,  14  of a vehicle body is schematically illustrated in  FIGS. 2 a  and 2 b   . The device  16  comprises a carrier  11 , which has an edge region  21 . The adhesive  13  is in this case arranged substantially on said edge region  21  of the carrier  11 . 
     A gap exists between the device  16  and the structural element  12 ,  14  prior to the expansion of the adhesive  13 . Said gap permits the structural element  12 ,  14  to be coated in order to achieve an anti-corrosion protection of the structural element  12 ,  14 . After said coating, the adhesive  13  is usually expanded by way of a thermal influence, wherein the expanded adhesive  13 ′ closes the gap between the device  16  and the structural element  12 ,  14  as a result. Fixing of the device  16 ′ in the structural element  12 ,  14  is moreover also simultaneously achieved as a result of the expansion of the adhesive  13 . A device  16 ′ that is fastened in the structural element  12 ,  14  in such a manner reinforces the structural element  12 ,  14 , on the one hand, and closes the cavity in the structural element  12 ,  14 , on the other hand. 
     It is a disadvantage of the previously known sealing and/or reinforcing elements that, in the majority of cases, an individually adapted element has to be produced for each vehicle body shape and for each cavity of a vehicle body. This leads to high development and production costs, and is disadvantageous in particular in the case of relatively small vehicle series. 
     Furthermore, the known sealing and/or reinforcing elements have the disadvantage that they can often only insufficiently seal or reinforce regions which are difficult to access in complex cavities. 
     It is therefore an object of the present invention to provide an improved system for insulating a structural element in a motor vehicle, which avoids the disadvantages of the prior art. The system is intended to give rise in particular to economic advantages in the case of relatively small unit quantities and to reduce development and production complexity overall. Furthermore, the intention is to ensure better filling of difficult-to-access portions of cavities. 
     Said object is achieved by a system for insulating a structural element in a motor vehicle, the system comprising: a structural element having a first constituent part and a second constituent part, wherein the constituent parts are joined together at a first joining point and at a second joining point, and wherein the structural element forms a cavity; a device having a carrier and a first expandable adhesive, wherein the carrier is arranged on the first constituent part of the structural element by way of a fastening element; and a second expandable adhesive which is arranged on the second constituent part of the structural element; wherein the first expandable adhesive and the second expandable adhesive are in a non-expanded state and are configured, and arranged, in such a way that, after an expansion, the device and the second expandable adhesive substantially completely fill a cross section of the structural element. 
     Said solution firstly has the advantage that various structural elements can be insulated by such a system with a single standardized device. In this case, the device with the first expandable adhesive in particular fills a large part of the cavity in the structural element. The second expandable adhesive is used in particular in regions of the cavity which are difficult to access, and thus difficult to fill, with the device. Since the second expandable adhesive is applied individually and directly onto the structural element, an amount and a shape of the second expandable adhesive can be adapted individually to the respective structural element. It is thus the case that no individual devices need be produced for different structural elements or for different cavities of the structural element, it rather being the case that a large spectrum of different structural elements can be covered with one standardized device or with a few standardized devices in conjunction with the second expandable adhesive. 
     A core concept of the present invention consists, firstly, in providing a device which can be used to insulate a standardized cavity of structural elements. A second expandable adhesive, which can be used, as needed, for a specific (possibly irregularly formed) cavity of a structural element, is then added to said device. The device can thus be produced in high unit quantities, and the second expandable adhesive can be introduced into the structural element using favorable production and application methods (in particular by pumping or extrusion). As a result, lower overall costs can be achieved than if an individually manufactured device were to have to be produced for each cavity. In addition, the variable use of the second expandable adhesive makes it possible to achieve better filling of difficult-to-access regions of the cavities. 
     In the context of this invention, the designation “insulation” or “insulated” comprises elements or functions or structures or method steps for isolating and/or closing and/or reinforcing and/or damping and/or insulating a structural element. These various properties of such an insulation can in this case arise individually or else in combination with one another. 
     The structural element comprises at least a first constituent part and a second constituent part which are joined together at a first joining point and at a second joining point and thus form a cavity. In this case, the first and the second constituent part of the structural element can be composed in each case of one element or else of a plurality of elements. The structural element can therefore also have more than two joining points. 
     In one exemplary embodiment, the system comprises a plurality of devices having a carrier and a first expandable adhesive. By way of example, the system comprises two devices, three devices, four devices, five devices, more than two devices, more than three devices, more than four devices, or more than five devices. 
     In this case, both the shape and the materials of said plurality of devices can in each case be the same or different. 
     By way of example, the carrier of a first device and the carrier of a second device can thus have the same or a different shape, and the first expandable material of the first device and the first expandable material of the second device can for example have the same or different expansion rates or compositions or moduli of elasticity in an activated state. 
     In one exemplary embodiment, the device has a compact form. 
     In one exemplary embodiment, the device has substantially the form of a cuboid or cylinder or truncated cone or cone or cone of revolution. 
     The formation of a compact device has the advantage that, as a result, the device is robust in use and can be stacked efficiently. Such a form of the device is also advantageous for the uniform filling of a main region of the cavity of the structural element. 
     In one exemplary embodiment, the carrier and the first expandable adhesive together have a thickness of at least 3 mm or at least 4 mm or at least 5 mm or at least 10 mm on a total base area of the device. 
     This in turn has the advantage that a compact form of the device is suited more robust, more easily stackable and transportable and better suited for the foaming of main regions of the cavities. 
     In one exemplary embodiment, the first expandable adhesive forms a single cohesive element. In an alternative embodiment, a plurality of non-cohesive first expandable adhesives form a plurality of non-cohesive elements. 
     In one exemplary embodiment, the first expandable adhesive has an expansion rate of 1000 to 3000%. In one exemplary development, the first expandable adhesive has an expansion rate of between 1000 and 2700% or between 1500 and 2500%. 
     An exemplary material with such an expansion rate can be obtained under the trade name Sika Baffle® 455. 
     In an alternative embodiment, the first expandable adhesive has an expansion rate of 50 to 500%. In one exemplary development, the first expandable adhesive has an expansion rate of between 70 and 400% or between 100 and 300%. 
     An exemplary material with such an expansion rate can be obtained under the trade name Sika Reinforcer® 940. 
     In one exemplary embodiment, the carrier and the fastening element are configured in one piece. 
     In a further exemplary embodiment, the carrier and the fastening element are formed from the same material. 
     In one exemplary embodiment, the first adhesive is arranged on the carrier by an injection-molding process. 
     In one exemplary embodiment, the carrier is produced by an injection-molding process. 
     In one exemplary embodiment, the carrier and the first adhesive are produced by a two-component injection-molding process. 
     In one exemplary embodiment, the carrier comprises a plastic, in particular polyamide. 
     In one exemplary embodiment, the carrier comprises a fiber-reinforced plastic, in particular a glass fiber-reinforced or carbon fiber-reinforced plastic. 
     In principle, the carrier can be composed of various materials. Preferred materials are plastics, in particular polyurethanes, polyamides, polyesters and polyolefins, preferably polymers which can withstand high temperatures such as poly(phenylene ethers), polysulfones or polyether sulfones, which in particular are also foamed; metals, in particular aluminum and steel; or grown organic materials, in particular wood materials or other (densified) fibrous materials, or glass-type or ceramic materials; especially also foamed materials of this type; or any desired combinations of these materials. Polyamide, in particular polyamide 6, polyamide 6.6, polyamide 11, polyamide 12, or a mixture thereof, is particularly preferably used. Combinations with fibers, such as, for example, glass fibers or carbon fibers, are also possible. 
     Furthermore, the carrier can have any desired construction and any desired structure. It may be solid, hollow, or foamed, or have a grid-like structure, for example. Typically, the surface of the carrier may be smooth, rough or structured. 
     In one exemplary embodiment, the second expandable adhesive 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%. 
     An expandable and pumpable adhesive of this kind is described, by way of example, in European patent application EP 3 281 970 A1. 
     An example of an expandable, pumpable adhesive of this kind is an adhesive obtainable under the trade name Sikaseal®. 
     An example of a second expandable adhesive, which can be extruded, can be obtained under the name SikaBaffle® 455. 
     In one exemplary embodiment, the second expandable adhesive is arranged in the form of a bead or a plurality of beads on the second constituent part of the structural element. 
     In one exemplary embodiment, the second expandable adhesive is arranged on the second constituent part of the structural element by way of a robot. 
     In one exemplary embodiment, the at least one bead has a diameter of 2 to 20 mm or of 4 to 18 mm or of 6 to 16 mm. 
     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. 
     In one exemplary embodiment, the second expandable adhesive contacts the structural element at the first joining point and at the second joining point. 
     In one exemplary embodiment, in the region of the first and the second joining point, the second expandable adhesive in each case touches both the first constituent part of the structural element and the second constituent part of the structural element. 
     In one exemplary embodiment, the second expandable adhesive has, in each case proceeding from the joining points, an extent along the second constituent part of the structural element of at least 10 mm or of at least 15 mm or of at least 20 mm or of at least 30 mm or of at least 40 mm. 
     In one exemplary embodiment, the second expandable adhesive forms a continuous element between the first joining point and the second joining point. 
     In one exemplary embodiment, the second expandable adhesive forms a single cohesive element. In an alternative embodiment, a plurality of non-cohesive second expandable adhesives form a plurality of non-cohesive elements. 
     In one exemplary embodiment, the second expandable adhesive is a pumpable or extrudable material. 
     In one exemplary embodiment, the second expandable adhesive can be pumped at a temperature of less than 80° C., preferably of less than 70° C., preferably of less than 60° C., particularly preferably of less than 50° C. 
     In one exemplary embodiment, the second expandable adhesive can be extruded at a temperature of less than 100° C., preferably of less than 90° C., preferably of less than 80° C., particularly preferably of less than 70° C. 
     In one exemplary embodiment, the second expandable adhesive can be pumped or extruded at a temperature which lies below an activation temperature of the second expandable adhesive by at least 20 K or by at least 30 K or by at least 40 K or by at least 50 K or by at least 60 K. 
     The object set in the introduction is additionally achieved by a method for insulating a structural element in a motor vehicle, the method comprising the steps of: providing a device having a carrier and a first expandable adhesive; arranging the device on a first constituent part of the structural element; arranging a second expandable adhesive on a second constituent part of the structural element; joining the first constituent part and the second constituent part of the structural element in order to form the structural element, wherein the device and the second expandable adhesive are arranged in a cavity between the constituent parts of the structural element; and expanding the first expandable adhesive and the second expandable adhesive, as a result of which a cross section of the structural element is substantially completely filled by the device and the second expandable adhesive. 
     In one exemplary embodiment, the method is carried out using a system according to the description above. 
     In one exemplary embodiment, the second expandable adhesive is arranged on the second constituent part of the structural element by way of a robot. 
     In one exemplary embodiment, the second expandable adhesive is pumped or extruded onto the second constituent part of the structural element. 
     In one exemplary embodiment, the second adhesive is arranged on the second constituent part of the structural element before or after the device has been arranged on the first constituent part of the structural element. 
     In one exemplary embodiment, during the expansion operation, a temperature of at least 100° C. or at least 120° C. or at least 140° C. is applied for the activation of the adhesives. 
     In one exemplary embodiment, heat is employed during the activation of the first expandable adhesive and of the second expandable adhesive, in particular the adhesives are activated in a finishing oven. 
    
    
     
       Details and advantages of the invention will be described below on the basis of exemplary embodiments and with reference to schematic drawings, in which: 
         FIG. 1  shows an exemplary illustration of a vehicle body according to the prior art; 
         FIGS. 2 a  and 2 b    show schematic illustrations of an exemplary device according to the prior art; 
         FIGS. 3 a  to 3 f    show schematic illustrations of exemplary devices; and 
         FIGS. 4 a  and 4 b    show schematic illustrations of an exemplary system for insulating a structural element. 
     
    
    
       FIGS. 3 a  to 3 f    illustrate various exemplary embodiments of devices  16 . In these exemplary embodiments, the device  16  has a carrier  11  in addition to the first expandable material  13 . 1  in each case. In this case, the device  16  or the first expandable adhesive  13 . 1  is illustrated in each case in a non-expanded state. 
     In these exemplary embodiments, the device  16  in each case has a compact form and is of substantially cuboidal configuration. 
     To arrange the device  16  on a structural element, the device  16  in each case has at least one fastening element  5 . Said fastening element  5  can in this case be of different design, for example in the form of a clip, in the form of a welding tab, in the form of a magnetic element or in the form of an adhesive. 
     In  FIG. 3 a   , the carrier  11  is formed with a cross-like cross section which is anchored in the first expandable adhesive  13 . 1 . The fastening element  5  in the form of a clip is formed integrally on said cross-like carrier  11 . 
     In  FIG. 3 b   , the device  16  is likewise formed with a carrier  11  and a first expandable adhesive  13 . 1  arranged thereon. In this exemplary embodiment, the device  16  has two fastening elements  5  which are both integrated in the carrier  11  as magnetic materials. 
       FIG. 3 c    illustrates a further exemplary embodiment of a device  16 . In this exemplary embodiment, the carrier  11  is arranged in the center in the first expandable adhesive  13 . 1 , and a fastening element  5  is formed integrally in the form of a clip on the carrier  11 . 
     A further exemplary device  16  is illustrated in  FIG. 3 d   . In this exemplary embodiment, the carrier  11  has a first plate and a second plate. The first expandable adhesive  13 . 1  is in this case arranged between said plates of the carrier  11 . Furthermore, the fastening element  5 , again in the form of a clip, is formed integrally on the carrier  11 . 
     A further exemplary device  16  is illustrated in  FIG. 3 e   . In this exemplary embodiment, the first expandable adhesive  13 . 1  is substantially enclosed by the carrier  11 . In this case, the carrier  11  has openings, through which the first expandable adhesive  13 . 1  can expand during expansion. A fastening element  5  in the form of a welding tab is formed integrally on the carrier  11 . 
     A further exemplary device  16  is illustrated in  FIG. 3 f   . In this exemplary embodiment, the device  16  again has a first expandable adhesive  13 . 1  and a carrier  11 . In this exemplary embodiment, the carrier  11  comprises a first plate and a second plate. In this case, the fastening element  5  in the form of a clip is formed integrally on the first plate. 
     An exemplary and schematically illustrated embodiment of a system  1  for insulating a structural element  12 ,  14  is depicted in  FIGS. 4 a  and 4 b   . In this case, the first expandable adhesive  13 . 1  and the second expandable adhesive  13 . 2  are in a non-expanded state in  FIG. 4 a   , and in an expanded state in  FIG. 4   b.    
     The system  1  comprises a structural element  12 ,  14  having a first constituent part  12 . 1 ,  14 . 1  and a second constituent part  12 . 2 ,  14 . 2 . The constituent parts  12 . 1 ,  14 . 1 ,  12 . 2 ,  14 . 2  of the structural element  12 ,  14  are in this case joined together at a first joining point  6  and at a second joining point  7 , as a result of which a cavity  3  is formed. 
     In this exemplary embodiment, it can be seen that the device  16  is arranged in the cavity  3  of the structural element  12 ,  14  in such a way that the first expandable adhesive  13 . 1  can fill a main region of the cavity  3 . In this case, the second expandable adhesive  13 . 2  is arranged on the second constituent part  12 . 2 ,  14 . 2  of the structural element  12 ,  14  in such a way that in particular the regions of the joining points  6 ,  7  can be substantially completely filled. 
     It can also be seen in  FIG. 4 a    that the second expandable adhesive  13 . 2 , in a non-expanded state, contacts the structural element  12 ,  14  in the region of the joining points  6 ,  7 . This serves in particular to make it possible to substantially completely fill those regions of the joining points  6 ,  7  which are difficult to access. 
     In this exemplary embodiment, the second expandable adhesive  13 . 2  is also in particular used to substantially completely fill a difficult-to-access region of the cavity  3 , said region extending toward the second joining point  7 . 
     LIST OF REFERENCE DESIGNATIONS 
     
         
           1  System 
           3  Cavity 
           5  Fastening element 
           6  First joining point 
           7  Second joining point 
           10  Vehicle body 
           11  Carrier 
           12  Structural element 
           12 . 1  First constituent part 
           12 . 2  Second constituent part 
           13  Adhesive 
           13 . 1  First expandable adhesive 
           13 . 2  Second expandable adhesive 
           14  Structural element 
           14 . 1  First constituent part 
           14 . 2  Second constituent part 
           16  Device 
           21  Edge region