Interior panel part with airbag cover

An interior panel for the interior of a vehicle and a method for the production thereof. The interior panel has first and second layers and with the first layer having an air bag cover region extending over an air bag opening in the second layer. The interior panel has a connecting part which is formed from: a first fastening section which is fastened to the airbag cover region of the first layer, a second fastening section which is fastened to the lower side of the second layer, and a coupling section situated between the first fastening section and the second fastening section. The coupling section is made of flexible material such that the airbag cover region may be partially separated from the first layer during airbag deployment while being held by the coupling section.

This application claims the benefit of the filing date of German Patent Application No. DE 10 2011 102 521.2, filed on May 26, 2011, the entire disclosure of which application is hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an interior panel part for a vehicle and in particular an interior panel part with an airbag cover region for covering a passage opening of the airbag of an airbag device and a method for the production of the interior panel part.

BACKGROUND OF THE INVENTION

Interior panels are known from the prior art, in particular as instrument panels, which can be provided at suitable sites—on the passenger side in the case of the instrument panel—with an airbag flap. Usually, these interior panels or respectively instrument panels have several layers with a different function: a support layer, which can be provided with an intermediate layer, which is applied on the support layer, and a decorative layer, which is mounted on the visible side of the intermediate layer, facing the passenger compartment. The airbag flap is frequently formed by the support-, the intermediate- and the decorative layer, wherein weakenings are provided on the side facing away from the visible side, which usually follow the outline of the airbag flap.

In order to prevent a tearing off of the airbag flap on the expanding of the airbag, usually rebound straps are used, which are connected in a form- or force-fitting manner on the one hand with the cover of the airbag passage opening and on the other hand with the instrument panel. In the prior art, woven or knitted fabrics, constructed in the manner of a net, are frequently used, as known from DE 20 2007 016 718 U1. These flexible connecting structures of a woven or knitted fabric act in the installed state in the instrument panel in a similar manner to a film hinge and can prevent a tearing off of the cover.

DE 195 30 243 A1 and DE 10 2008 019 950 A1 show examples of application of rebound straps for securing an airbag flap on a steering wheel hub or respectively on an instrument panel.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an interior panel part with an airbag cover region for a vehicle, which is able to be produced inexpensively and nevertheless functions reliably.

In particular, it is an object of the present invention to provide a method for the production of an interior panel part according to the invention with an airbag cover region, which is favorably priced and nevertheless reliable.

With the interior panel part according to the invention, advantageously a flexible connecting part can be mounted on the one hand in a section of the instrument panel and on the other hand in an airbag cover region, covering a passage opening, beneath a possible decorative layer and support layer. In the prior art, it is usual to arrange the flexible connecting part between a decorative layer and a support layer. If, in such an arrangement of the connecting part, the cover is now pushed open by the airbag, the forces which occur are transferred directly to the connecting site between the decorative layer and the support layer of the connecting part. It can arise that owing to the forces which occur, the connection between the decorative layer and the support layer tears open. This tearing open damages the instrument panel generally so intensively that a repair and an exchanging of only the airbag flap is not worthwhile, but rather the entire interior panel frequently has to be exchanged. In particular in the case of instrument panels, depending on the decorative materials used, this can be correspondingly expensive and laborious. In addition, through the tearing open of the decorative layer and of the support layer, also the fabric connecting structure forming the film hinge can be detached and, together with the airbag cover, can be separated from the instrument panel through the forces of the expanding airbag which occur, whereby in turn the risk of injury increases. With the advantageous embedding of the flexible connecting part on the one hand on the airbag cover and on the other hand beneath a supporting structure, the advantage is produced that no additional fastening means, such as fastening strips, are necessary on the airbag cover region etc., which increase the mass of the airbag cover. Through the smaller mass of the airbag cover, the risk of a tearing off of the airbag cover from the instrument panel in the case of an airbag expansion is limited. The smaller mass also brings about a lower mass moment of inertia, whereby smaller forces act on the interior panel part in the case of an airbag expansion, so that the interior panel part must be constructed so as to be less rigid, the latter therefore has less weight, which as a whole has a positive effect on the overall weight of the vehicle and the production of the interior panel part, which can also mean lower material costs and a lower fuel consumption in motor vehicles.

The embedding of the fastening section, provided on the connecting part, preferably takes place by an injection molding method. With injection molding methods, it is possible to produce a sufficient force-fitting and form-fitting connection between the flexible connecting part and the airbag cover.

In an advantageous embodiment, the connecting part is a netlike woven fabric or knitted fabric. This has the advantage that, as already mentioned above, a sufficiently secure and nevertheless light and tear-proof connection is formed between the cover and the instrument panel. The woven or respectively knitted fabrics can be produced from various yarns or fibers, which have various strengths according to the stress and arrangement. For example, in the basic structure of the connecting part, tear-proof fibers or yarns can be integrated accordingly.

According to an embodiment of the interior panel part according to the invention for the interior of a vehicle, the interior panel part has a first layer facing a first side and a second layer which is fastened to the first layer with a lower side, which faces a second side situated opposed to the first side, and which has an encircling margin region and an airbag passage opening defined through this, wherein the first layer has a main region and an airbag cover region covering the passage opening and is embodied such that the airbag cover region is able to be at least partially separated from the main region by an airbag expanding from the second side, wherein the interior panel part has a connecting part which is formed from: a first fastening section, which is fastened to the airbag cover region of the first layer, a second fastening section, which is fastened to the lower side of the second layer, and a coupling section situated between the first fastening section and the second fastening section, which coupling section is made from flexible material and is designed such that the airbag cover region, after its at least partial separation from the main region, is held by the coupling section.

The first layer is preferably constructed as a support layer. However, it is also possible that the second layer is also at least partially constructed as a support layer. In addition, the first and the second layer can be constructed such that they function as a support layer in the state when mounted on one another. The airbag or respectively the airbag device is situated in the original position on the side of the second layer. Through the configuration of the interior panel component from two layers, advantageously particularly complicated, nested and/or undercut interior panel components can be produced. In addition, through the configuration of the interior panel component from two layers, the result is that in the region of the airbag cover only one layer needs to be provided, which has the advantage that the airbag cover has a lower weight than multi-layered airbag covers. In the case of the tearing open of the airbag cover by an expanding airbag, owing to the lower weight a fastening of the airbag cover on the main region, in particular on the second layer can be embodied in a less extensive manner, which in turn can mean a reduction in material and weight. In addition, through the arrangement of the connecting part on the lower side of the second layer, the advantage is produced that the forces acting on the connecting part in the case of an airbag expansion can be conveyed in a particularly favorable manner to the interior panel component, without additional measures being necessary for reinforcing the component.

According to an embodiment of the interior panel part in accordance with the invention, the first fastening section and the second fastening section of the connecting part are spaced apart from one another such that the coupling section between the two fastening sections is constructed as an exposed section, in particular a loop. This has the advantage that the airbag cover region has a sufficient clearance to flap open when an airbag expansion occurs, without the airbag cover being able to impede the expansion of the airbag. Nevertheless, it is ensured that the airbag cover region is fastened sufficiently securely to the second layer of the interior panel part by the connecting part.

According to another embodiment according to the invention of the interior panel part, the first fastening section and the second fastening section are spaced apart from one another such that the coupling section is constructed as a film joint or hinge joint, wherein the first fastening section adjoins the margin region with a margin section. This has the advantage that too intensive a swinging open or respectively springing away of the airbag cover can be prevented, in particular when the installation space which is available or the passenger compartment sets limits for the folding open of the airbag cover. In addition, with the film joint the expansion direction of the air bag can be partly controlled.

According to another embodiment according to the invention of the interior panel part, the second fastening section of the flexible connecting part is embedded in a fastening strip which is mounted on the second layer. This has the advantage that the connecting part can be fastened better to the second layer, so that the most suitable material can be selected for the function of the connecting part.

According to a further embodiment according to the invention of the interior panel part, the fastening strip is provided with a first coupling device and the first layer is provided with a second coupling device, corresponding thereto, for the detachable, force-fitting and/or form-fitting coupling with one another of the fastening strip on the first layer. A coupling device is to be understood herein to mean a device which permits a non-destructive mounting of the fastening strip on the first layer. Preferably, the coupling device is embodied as a plug/bush connection, provided with a press fit. This non-destructive mounting has the advantage that no additional measures are necessary for the mounting of the fastening strip on the first layer, which permits a quicker production.

According to an embodiment according to the invention of the interior panel part, the first coupling device of the fastening strip is a plug device and the second coupling device of the first layer is a plug mount device, or vice versa, which together form a detachable press fit. The coupling device can, however, also be embodied as a tongue-and-groove connection, so that a lateral pushing of the fastening strip on the first layer is possible. It is essential here that the mounting of the fastening strip on the first layer permits a non-destructive dismantling and the mounting is sufficiently secure that the fastening strip, on the subsequent fastening and/or joining method cannot become separated from the first layer.

In an embodiment according to the invention of the interior panel part, the plug device is constructed as plug-in pins or plug-in strips, which are arranged in series, linearly, parallel and/or offset with respect to one another, with the plug mount devices being provided in corresponding positions. The position of the plug-in pins or plug-in strips and their corresponding plug mount devices are not limited to the positions mentioned above. Rather, the positions are to be selected so that always an optimum fastening of the fastening strip on the first layer is possible.

According to an embodiment according to the invention of the interior panel part, the flexible connecting part is formed from a netlike woven or knitted fabric, which has a sufficient resistance to tearing. The connecting part which connects the airbag cover region with the second layer has the function of a rebound strap, which is intended to prevent a tearing off of the airbag cover region which is pushed open by the expanding airbag. The connecting part can be produced entirely from a woven or knitted fabric, but also from any other material which is suitable as a rebound strap. The connecting part can, however, also consist of flexible and non-flexible sections, in particular at the fastening sections of the connecting part situated at the end sections.

According to an embodiment in accordance with the invention of the interior panel part, the first layer is provided to the side of the airbag cover region with a first assembly region for mounting with the second layer, wherein the second layer on the margin region to the airbag passage opening has a second assembly region complementary to the first assembly region of the first layer. The assembly region of the first and the second layer is preferably constructed such that the region is suitable for an ultrasonic vibration welding.

In an embodiment according to the invention of the interior panel part, the first assembly region of the first layer is constructed as a first sequence of a groove and a web, and the second assembly region of the second layer is formed with a second sequence of a groove and a web, which are arranged offset with respect to one another such that a groove of the one layer is associated with a web of the other layer. This offset arrangement has the advantage that grooves and webs, constructed so as to be complementary to one another, permit a precise positioning of the one layer on the other layer.

In an embodiment according to the invention of the interior panel part, the margin region of the passage opening for the airbag of the airbag device is reinforced with a reinforcing rib. This has the advantage that the forces which are conveyed from the connecting part to the margin region, which are caused by the expanding airbag, can be better conveyed to the second layer.

In an embodiment according to the invention of the interior panel part, the fastening strip is mounted on the reinforcing rib. This has the advantage that no further fastening measures are necessary on the second layer.

In an embodiment according to the invention of the interior panel part, the first and second layers are made from a plastic material. As plastic materials, all materials are conceivable which are suitable as interior panel part in vehicle construction, such as for example TPO, ASA, ABS, PVC, etc.

In an embodiment according to the invention of the interior panel part, the airbag cover region is defined at least partially by a material weakening in the first layer. The material weakening is only necessary if the airbag cover region is produced from a material which is too rigid to automatically hinge on actuation of the airbag (defined according to opening geometry and opening speed).

In a method according to the invention for the production of an interior panel part for the interior of a vehicle, for an interior panel part with a first layer facing a first side and with a second layer which is fastened to the first layer with a lower side, which faces a second side situated opposed to the first side, and which has an encircling margin region and an airbag passage opening defined thereby, wherein the first layer has a main region and an airbag cover region covering the passage opening and is embodied such that the airbag cover region is able to be at least partially separated from the main region by an airbag expanding from the second side, the following steps are carried out for producing the above-mentioned interior panel part: inserting a flexible connecting part into a mold; mounting a section of the first layer of the interior panel part on a first fastening section of the flexible connecting part and mounting a fastening strip on the second fastening section of the flexible connecting part by means of the mold; and removing from the mold the flexible connecting part together with the first layer of the interior panel part mounted on its one fastening sections and of the fastening strip mounted on its other fastening section. The fastening strip is firstly coupled on the first layer detachably such that the first layer can be permanently connected together with the second layer at predetermined assembly regions by means of an assembly method. The mounting of the fastening strip on the first layer has the advantage that the fastening strip cannot have an intrusive effect in the subsequent method steps, such as for example being able to arrive into the assembly regions of the first and second layer.

In a method according to the invention, the fastening strip is mounted on the first layer by means of a detachable non-destructive coupling, such as in particular an adhesive connection or a detent connection, wherein the coupling is sufficiently secure so that the fastening strip cannot become detached in a subsequent assembly method. On coupling of the first layer to the second layer, preferably connections are selected which permit a quick but non-destructive and temporary mounting of the fastening strip on the first layer.

In a method according to the invention, a protective cap is mounted to protect the fastening strip and the flexible connecting structure. The protective cap is intended to protect the fastening strip and the connecting part from the negative influences of the fastening- and joining methods, which are used for the permanent fastening of the first layer to the second layer.

In a method according to the invention, the first layer is arranged on the second layer of the interior panel part one over the other such that the first and the second layer can be connected with one another at their assembly regions by means of an assembly method, such as vibration welding, ultrasonic welding, heated tool welding, infra-red welding, hot gas welding, spot welding, friction welding, high frequency welding, circular welding, laser beam welding, in particular a joining method which is suitable for the permanent connecting of plastics. The fastening of the first layer to the second layer can, however, also be carried out by other joining and fastening methods. It is essential here that the first and the second layer are connected sufficiently securely and permanently with one another.

In a method according to the invention, the fastening strip is connected with the second layer by means of a joining method and/or by means of a screwing- or detent method. As joining methods here inter alia ultrasonic riveting methods are conceivable. However, the fastening- and joining methods can also be used, which are able to be applied for the permanent fastening of the first and second layer. In screwing or detent methods, the advantage exists that a simpler subsequent dismantling is possible, for example in order to be able to better recycle the material of the interior panel part which is used.

In a method according to the invention, the fastening strip is mounted on a side of the second layer which is opposed to the side of the assembly regions of the second layer.

In a step of the method according to the invention, the first layer is weakened at least in parts along an edging of the airbag cover region, preferably by laser irradiation. The material weakening of the first layer can take place before or after the mounting of the second layer. Other methods suitable for material weakening can also be used, such as cutting, scoring, stamping or melting. It is essential that the material weakening is embodied such that an expanding airbag can push open the airbag cover region. When the material forming the airbag cover region is sufficiently rigid, such a weakening can be dispensed with, when the expanding airbag can push open the airbag cover region of this material without limitations to safety being hereby brought about.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

According to the invention, generally an interior panel part of a vehicle is provided with a passage opening50for an airbag of an airbag device60to pass through from an airbag chamber in the interior of the vehicle, arranged beneath the panel part, from the viewpoint of the occupant. InFIG. 1an instrument panel is provided as an embodiment of the interior panel part1according to the invention. According to the invention, the interior panel part can also be a different interior panel part, e.g. an interior panel part for the side of the vehicle interior, e.g. for the covering and passing through of a side airbag. Generally, the concern is therefore with an interior panel part with a passage opening50for the airbag of an airbag device60, which is able to be covered by the interior panel part.

InFIG. 1a diagrammatic view is illustrated of an interior panel part1according to the invention, with a first layer10and a second layer30. The first layer10is formed from a main region100and an airbag cover region20. The airbag cover region20is delimited in the embodiment illustrated inFIG. 1by an edging region17of the main region100. The edging region17can be embodied so as to be visible from the exterior, i.e. from a visible side or first side51, or so as to be non-visible. In the intended installation of the panel part, the first side1is the interior of the vehicle. The main region100is provided on its lower side, which faces a second side S2, situated opposed to the first side, with a second layer30and is connected in a laminar manner therewith.

The edging section17runs externally around an airbag cover or an airbag covering, so that the edging region17is situated outside the embodiment, illustrated inFIG. 1, of an optionally provided material weakening line13in the interior panel part1. The material weakening13is embodied such that an expanding airbag can push open the airbag cover region20. The first layer10can also be realized without a material weakening13or an only partially formed and therefore not encircling weakening line, when the material from which the instrument panel1or respectively the airbag cover region is formed has a rigidity at which an expanding airbag can reliably push through this region. InFIG. 1a first layer10of the instrument panel is shown. In the illustrated embodiment, the first layer10has on the side S1facing the passenger compartment a decorative seam mount18, which is provided for a decorative seam (not illustrated) of a decorative layer. The first layer10can be laminated with a decorative layer (not illustrated).

InFIG. 2a diagrammatic sectional view is illustrated according to the cross-section A-A inFIG. 1of the interior panel part1according to the invention, without a decorative layer with an airbag device60, the outer side of which faces a first side, which in relation to the interior panel part1is situated opposed to a second side S2which faces away from the passenger compartment. The visible side S1or outer side corresponds to the side of the instrument panel illustrated inFIG. 1, which faces the passenger compartment of a motor vehicle, when the interior panel part1is installed in a vehicle. On the second side2therefore substantially all the structural elements are arranged, which are to be covered by the interior panel part1, such as for example an airbag device60.

On the cover region lower side10aof the first interior panel part layer10, facing the second side S2, a flexible connecting part40is fastened such that the latter connects the main part100and the cover region20, in order to prevent a complete separation of the airbag cover region20from the main part100by an expanding airbag. The flexible connecting part40has: a first fastening section41, which is mounted on the cover region lower side10aof the cover region20, a second fastening section42, which is mounted via a fastening strip70on the lower side30aof the second layer30, and a coupling section43, which is arranged between the first fastening section41and the second fastening section42and connects the two fastening sections41and42with one another such that a tearing off of the airbag cover region20from the main part of the interior panel part1by an expanding airbag is prevented on the side at which the airbag cover region is connected with the flexible connecting part40. The first fastening section41of the flexible connecting part40is mounted on the side of the visible layer10which faces the inner side S2.

The fastening strip70in the embodiment shown inFIG. 1is preferably mounted on the fastening section42in an injection molding method, wherein the fastening strip70embraces the second fastening section42of the flexible connecting part40in the longitudinal and width direction completely or over a predetermined length.

The interior panel part2shown inFIGS. 1 and 2has substantially two layers: a first layer10and a second layer30. The first layer10has the main part100, which is fastened to the second layer30, provided as supporting, and a cover region11, which forms the airbag cover region20and covers a passage opening50for an expanding airbag of an airbag device60. The two layers10,30form together the non-laminated base of an interior panel part1. The interior panel part1of the embodiment shown herein, has a complicated geometry, owing to the broken-out sections for the ventilation openings and the accommodation for the instrument display and further design-related specifications, which geometry is difficult to be able to produce in a single injection molding step. Therefore, the interior panel part1illustrated inFIG. 1is preferably formed from a first layer10and a second layer30, which are connected with one another in a joining or fastening method.

Advantageously, the two layers10,30are formed from plastics, wherein the two layers are preferably produced respectively individually in a separate injection molding or pressing method. The first layer10and the second layer30are then fastened to one another in a fastening or joining method according to the invention, explained herein below. The selected plastics must be accordingly suitable for the selected fastening or respectively joining method.

Preferably, when the two layers10,30are connected with one another, an additional third layer (not illustrated) is mounted on the upper side of the side of the first layer10facing the visible side S1. This additional layer is a lamination layer or decorative layer, which can consist of plastic, leather or a similar material or fabric which is suitable for the configuring of the passenger compartment of a vehicle. The third (not illustrated) layer can consist of two plies. The first ply, which adjoins the first layer10, can consist of a knitted fabric, woven fabric or a foam layer, and the second ply, which faces the visible side S1and is arranged on the first ply, can consist for example of leather or of a slush skin of plastic. The decorative layer can, however, also consist of other single-layered, double-layered or multi-layered materials suitable for vehicle construction.

In the embodiment illustrated inFIG. 2, in addition on the visible side S1of the instrument panel1, facing the passenger and the driver, on the first layer10a decorative seam mount18is provided to receive a decorative seam or decorative strip of decorative layers, which have such a decorative seam or decorative strip. The decorative seam mount18is necessary in particular when a decorative layer with a decorative or functional seam is mounted on the first layer10on the visible side S1. In particular when on the first layer10a so-called slush skin of plastic or another decorative layer without a decorative seam is applied, the interior panel part1can be formed without decorative seams or decorative strips. In this case, the decorative seam mount18is dispensed with.

As illustrated inFIG. 2, the airbag cover region20covers a passage opening50, constructed in the second layer30, for an airbag of an airbag device60to pass through. The main part100of the first layer10has an assembly region12which adjoins the airbag cover region20and is situated to the side of the passage opening50. At the section of the first layer10, to which the airbag cover region20and the main region100adjoin, a material weakening13is provided, which is formed laterally from the margin region32of the second layer30defining the passage opening50. The material weakening13of the first layer10can run partially or completely within the passage opening50or outside it. Preferably, the course of the material weakening13corresponds to the course of the edging17of the airbag cover region20, as indicated inFIG. 17.

The interior panel part1shown inFIG. 1is constructed as a so-called U-flap system. This means that there is only one flap or respectively the airbag cover region has only one pivot region. In this case, the material weakening13, which is intended to permit a tearing open of the airbag cover region20by an expanding airbag, is constructed with a U-shaped course in the surface of the interior panel part1facing away from the visible region, or respectively of the airbag cover region20. The pivot region of the flap is then the region where the flexible connecting part40is also arranged. InFIG. 2a material weakening13is also indicated at the pivot site of the airbag cover region on the margin region32, which material weakening is formed so as to be less intensive than the opposite material weakening13, so that a type of hinge is formed there.

It is, however, also possible to construct the interior panel part1according to the invention as an H-flap or multiple-flap system. This means that there are at least two flaps or respectively two pivot sites at which the flaps can pivot open. The course of the material weakening13, which is intended to permit a tearing open of the airbag cover region20by an expanding airbag, is then H-shaped. In an H-flap system, flexible connecting parts40are respectively provided at the respective pivot sites. The flexible connecting parts40are then provided respectively with a fastening strip70for fastening to the reinforcing ribs31to the left and right of the airbag device60, viewed in x1direction. It is, however, also conceivable that with several flexible connecting parts70before the assembly on the reinforcing ribs31firstly a shared fastening strip70is present, which is divided into individual fastening strips70for the assembly on the reinforcing ribs31.

The material weakening13is necessary when the expansion force of the expanding airbag is not sufficient to tear open the airbag cover region20such that owing to the material characteristics of the layers covering the passage opening50—for example too great an elasticity, too great a rigidity—a proper functioning of the airbag cannot be guaranteed.

The assembly region12or joining region of the first layer10preferably has a toothing of a sequence of webs14and grooves15(seeFIG. 7).

On the cover region lower side10aof the first layer10, a second layer30is provided adjoining the passage opening50, which second layer is fastened via a joining region or a second assembly region33of the second layer30with the assembly region12of the first layer10in a form- and/or force-fitting manner. The second assembly region33of the second layer30is constructed in a complementary manner to the first assembly region12with a sequence of webs34and grooves35(seeFIG. 7), so that the two regions can be fastened to one another by a suitable fastening or joining method, such as for example vibration welding. The assembly regions12and33of the first layer10and of the second layer30can, however, also have a different design. It is only essential here that they are suitable for the selected joining or fastening method for fastening the first layer10to the second layer30.

The construction of the assembly regions21,33illustrated inFIG. 7is particularly well suited for a vibration welding method for fastening the first layer10to the second layer30. However, other embodiments of the assembly regions21,33are also possible. For example, the assembly regions21,33can be constructed in accordance with a dovetail joint for the construction of a form-fitting connection, similar to a tongue-and-groove connection, which are then connected with one another permanently in a subsequent fastening method.

The second layer30in this embodiment is the supporting layer and has the task of giving the instrument panel a sufficient stability. The margin region32, which defines the passage opening50for an expanding airbag is also formed by the second layer30or supporting layer.

The margin region32of the second layer30preferably follows the course of the edging17and is provided with a reinforcement. In the embodiment of the interior panel part1shown inFIG. 2, the reinforcement is formed from reinforcing ribs31which are arranged in pairs on the margin region32of the second layer30and extend away from a lower side30aof the second layer30towards the inner side S2. The lower side30ais the side of the second layer30which faces away from the assembly region33of the second layer30, as also shown inFIG. 2. The reinforcement of the margin region at the passage opening50can, however, also be achieved by different reinforcing measures, such as inlays of metal or plastic regions with increased stability or with an individual reinforcing accretion31. The reinforcement is preferably arranged encircling on the margin region32of the passage opening. However, it is also conceivable that the reinforcement is provided only partially encircling at the sites which are exposed to higher stresses. This has the advantage that a saving can be made on material and therefore the interior panel part1as a whole can be constructed so as to save more material and to be lighter.

As illustrated inFIG. 2, in an embodiment according to the invention the flexible connecting part40has a first fastening section41, a second fastening section42and a coupling section43formed between the first fastening section41and the second fastening section. The first fastening section41of the flexible connecting part is mounted by means of an injection molding method on the cover region lower side10aof the airbag cover region20and is embedded therein accordingly. It is, however, also possible to fasten the fastening section41by means of a suitable adhesive method to the airbag cover region20which is provided for this. It is essential here that in the mounting method the mass or respectively the weight of the airbag cover region20is not substantially increased. A greater mass or respectively a greater weight leads to a greater mass moment of inertia, which in turn on striking out of the airbag cover region must be conveyed into the adjoining region of the interior panel part1, which in turn requires a greater rigidity of these regions. A lower mass moment of inertia or respectively a smaller mass of the airbag cover region namely means that the corresponding interior panel part1must be constructed so as to be less rigid, that the latter therefore has less weight, which as a whole has a positive effect on the overall weight of the vehicle and the production of the instrument panel, wherein in addition, as a secondary effect, fewer material costs are incurred. The lower weight of the interior panel part1and the weight reduction of the overall weight of the vehicle connected therewith can, in addition, lead to a lower fuel consumption. Screw connections for fastening the flexible connecting part40to the airbag cover region20or fastening means which increase the mass of the airbag cover region20are therefore less preferred. In addition, in the case of screw connections the danger exists that by the expanding airbag, parts of the screw connection during the striking open of the airbag cover20are detached therefrom and can then be thrown around in an uncontrolled manner in the passenger compartment.

According to the embodiment of the interior panel part1according to the invention, shown inFIG. 1, the second fastening section42of the flexible connecting part40embedded in a fastening strip70is fastened by means of the fastening strip70on the reinforcing ribs31of the margin region32of the second layer30. The fastening strip70is preferably fastened by means of ultrasonic riveting (not illustrated) on the reinforcing ribs31. Screw connections or adhesive connections are also conceivable for the fastening of the fastening strip70or respectively of the second fastening section42of the connecting part40, mounted therein, on the reinforcing ribs31. It is essential here that the fastening strip70is mounted sufficiently securely on the reinforcing ribs31or respectively on the margin region. The fastening strip70can also be mounted on the lateral side30b(seeFIG. 2) of the reinforcing rib41, facing the margin region32, wherein the dimensions of the fastening strip70and/or of the reinforcing rib31are adapted to one another accordingly, i.e. the projection length of the reinforcing rib31can be adapted to the length of the reinforcing strip70. A mounting of the fastening strip70directly on the lateral side30bcan be preferred when the coupling section43is to act as a hinge.

In the embodiment shown inFIG. 1, the coupling section43of the flexible connecting part40is constructed as a loop, i.e. the coupling section43acts here rather as a rebound strap, because the S-shaped region of the coupling section43offers freedom of movement.

It is, however, also possible to construct only the coupling section43per se to be flexible and to construct the adjoining fastening sections41,42to be rigid such that the coupling section43acts as a film joint or as a hinge or structural joint. This can also be achieved in that the freely movable region of the coupling section43is moved closer to the margin region32, the S-shaped region is shortened, so that the freedom of movement is restricted. The coupling section43can be constructed in the corner region between the lateral side30bof the margin region32and the airbag inner side10aof the first layer as an L-shaped, flexible section, which then acts similarly to a film joint or hinge when the fastening sections41,42are arranged directly adjacent to this hinge region (not illustrated).

In the embodiment illustrated inFIG. 2, the flexible connecting part40is preferably made from a flexible material, woven fabric or knitted fabric, which has the same flexible characteristics and consists of the same material over the range of extent of the first fastening section41over the coupling section43to the second fastening section42. The fastening sections41,42can, however also have less flexibility than the coupling section43. Embodiments of the flexible connecting part40are even conceivable, in which the fastening sections42,42are constructed so as to be rigid and only the coupling section43has a flexibility such that a joint effect is present on the flexible section and the airbag cover region20is only able to be swung open at and via this flexible section. For example, in the rigidly constructed regions of the woven fabric or of the knitted fabric of the connecting part40, stabilizing or respectively reinforcing wires or plastic rods can be arranged in the fastening sections41,42.

In the embodiment illustrated inFIG. 2, the flexible connecting part40is a flat web of a textile woven fabric, the flat extension region of which along the direction x1and x2corresponds approximately to the course, as illustrated inFIG. 2, and along direction x3corresponds approximately to the width of the airbag cover region20along the direction of the cross-section A-A inFIG. 1. Direction x1, x2, x3is to be understood to mean respectively the directions which are indicated by the arrows of the coordinate system inFIG. 2.

The flexible connecting part40can, however, also consist of individual bands or strips arranged uniformly or non-uniformly parallel to one another, which are arranged respectively with a predetermined distance from one another on the one hand in the airbag cover region20on the cover region lower side10aof the first layer10and on the other hand on the lower side30of the second layer30. The bands or respectively strips are then arranged in a flatly extending fastening strip70. The ends of the individual bands or respectively strips can, however, also be received individually in corresponding fastening connection parts, which undertake the function of the fastening strip70, which are then able to be fastened to the fastening ribs.

InFIGS. 3 to 10a method is illustrated for the production of the embodiment of the interior panel part1shown inFIGS. 1 and 2.

InFIG. 3a mold80is shown diagrammatically, which has a first mold part81, a second mold part82and a third mold part83. Each mold part81,82,83has respectively on the mold inner side a first contour surface90, a second contour surface91, a third contour surface92and a fourth contour surface93, in order to form the first layer10, shown inFIG. 1, together with the fastening strip70on the flexible connecting part40for example in an injection molding or pressing method. In the production method which is shown, the first layer10and the fastening strip70are mounted on the flexible connecting part40in an injection molding method. However, other production methods are also conceivable, such as pressing, casting or hot-forming methods. Advantageously, the first layer10is produced in an injection molding or pressing method. It is also possible to produce the first layer10and the fastening strip70in separate molds. Preferably, the fastening strip70is firstly mounted on the second fastening section42of the flexible connecting part40and thereafter in another mold the first layer10is mounted on the first fastening section41of the flexible connecting part40, with the mounting methods being able to be respectively an injection molding and/or pressing method.

InFIG. 3the mold parts81,82,83are illustrated in an opened position, so that the flexible connecting part40can be inserted into the mold80, in order to provide this with the first layer10and the fastening strip70. As illustrated inFIG. 3, the individual mold parts81,82,83are provided with the contour surfaces90,91,92and93, in order to form the shown configuration features on the first layer10, such as for example the decorative seam mount18and the assembly region13, and on the fastening strip70a plug device71and a sequence of webs73and grooves74assembly region. As illustrated inFIG. 3, female- and male-like structures are formed on the contour surfaces of the respective mold part81,82,83of the mold80in the respective contour surface, so that the cavities formed by closing of the mold parts81,82,83correspond to the first layer10which is to be created and the fastening strip70. In the first mold part81for example on the first contour surface a decorative seam mount contour98is formed. Corresponding contour-providing regions and, if necessary, complementary sections are provided in the other mold parts82,83, as explained below.

In the first contour surface90of the first mold part81, a decorative strip mount contour98is provided as female-like structure for the formation of the decorative strip mount18on the first layer10.

In the second contour surface91of the second mold part82, both contour-providing sections of the cavity of the fastening strip70and also contour-providing sections of the cavity of the first layer10are formed: a groove-web contour96for the assembly region12of the first layer, a rib-web contour97bfor the formation of the fastening strip70with an additional peg structure94for the formation of pins of a plug device71(seeFIG. 5) on the fastening strip70. The pins of the plug device71are provided for a detachable press fit for assembly in corresponding plug mount devices16of the first layer10. In addition, in the second contour surface91of the second mold part82of the mold80a projection contour95is formed for the formation of the plug mount devices16of the first layer10to receive the pins of the plug device71.

In the third mold part83of the mold80, in the third contour surface92a contour-providing groove-web contour96is formed, and in the fourth contour surface93, facing away from the third contour surface92, the groove-web contour97a, corresponding to the groove-web contour97b, is formed for the formation of the cavity of the fastening strip70.

InFIG. 4an injection molding/pressing method step is shown for the production of the embodiment illustrated inFIG. 2of the first layer10, the flexible connecting part40and the fastening strip70. The mold80is illustrated in the closed state and on the flexible connecting part40the first layer10and the fastening strip70are already mounted by an injection molding method or by a pressing method on the fastening sections41and42of the connecting part40, wherein the coupling section43is formed as a loop.

InFIG. 5a preparatory method step is illustrated for the production of the interior panel part1shown inFIG. 2. The flexible connecting part40is now fastened on the one hand by its fastening section41with the first layer10and on the other hand by its fastening section42on the fastening strip70. In addition, on one side of the fastening strip70plug devices71are illustrated, preferably on the side of the fastening strip70which in the final assembly state of the fastening strip, as shown inFIG. 2, faces away from the lower side30aof the second layer30. This permits the pivot movement of the fastening strip70, illustrated inFIG. 5and indicated by the movement arrows300, to be carried out towards the first fastening section41of the flexible connecting part40, embedded in the first layer10, without the connecting part having to be turned or twisted in its coupling section43. This pivot movement, illustrated by the arrows300, is carried out in order to fasten the fastening strip70on the first layer10, as shown inFIG. 6.

In addition, as illustrated inFIG. 5, plug mount devices16are formed in the first layer10. Preferably, the plug mount devices16are recesses or grooves which are dimensioned such that the pins of the plug device71of the fastening strip70are able to be brought by means of a detachable press fit into engagement with the plug mount device16of the first layer10. In addition, the fastening strip70has a sequence of grooves73and webs74. This groove-web structure can facilitate the assembly of the fastening strip70on the second layer30, when the latter has accordingly correspondingly constructed surface structures. In addition, material can be saved hereby, and the second fastening section42of the connecting part40can be arranged better and more simply centrally in the fastening strip70.

FIG. 6illustrates an intermediate assembly step in the production of the interior panel part1illustrated inFIG. 2, wherein the fastening strip70is fastened by the flexible connecting part40on the side of the first layer10in a non-destructive manner and detachably, on which also the assembly regions12of the first layer10are formed. The position of the plug mount device16in the first layer10is preferably selected such that the coupling section43of the flexible connecting part40lies substantially flush and slightly taut against the first layer10, as illustrated inFIG. 6, so that the coupling section43can not impede the assembly steps which are still to be carried out.

The non-destructive and detachable assembly of the fastening strip70on the first layer10takes place by means of inserting the pins of the plug device71of the fastening strip70into the mounts of the plug mount device16of the first layer10. The plug devices71are preferably projections or pins which are constructed in one piece on the fastening strip70and which are able to be plugged or inserted into the mounts of the plug mount device16. The fastening strip70mounted on the first layer10is held in situ in the plug mount device16by the action of a press fit. This means that the dimensions of the plugs of the plug device71and the dimensions of the mount of the plug mount device16are selected such that the pin of the plug device71is able to be inserted into the mount of the plug mount device16and is able to be clamped and/or locked into position there.

The plug device71can also be formed from separate pins, which after the injection molding process for mounting the fastening strip on the flexible connecting part40are mounted at a suitable location, for example by gluing on.

After the fastening strip70has been mounted detachably on the first layer10with sufficient strength in a non-destructive manner, a protective cap200can be mounted on the first layer10, as illustrated inFIG. 7. The protective cap200fulfils a dual function: Firstly, it protects the flexible connecting part40from dirt and damage in the subsequent method steps, and secondly is prevents a swinging in of the flexible connecting part40into the assembly region12,33of the first layer10and of the second layer30, if the fastening strip70were to become detached from the first layer10prematurely and inadvertently during the subsequent method steps.

InFIG. 7the first layer10and the second layer30are illustrated separated from one another. The movement arrows400show a guiding toward one another of the first layer10to the second layer30in a suitable device or manually by a person. It is essential here that the respective assembly region12of the first layer10and the respective assembly region33of the second layer30are aligned and arranged correctly one over another, i.e. the toothings of the first layer10and of the second layer20engage into one another correctly. The toothings formed by the assembly regions12,13, owing to the sequence of webs14,34and grooves15,35, also offer a positioning aid for the correct positioning of the first layer10on the second layer30.

InFIG. 8the fastening of the first layer10onto the second layer30by vibration welding is illustrated diagrammatically This is indicated by the vibration arrows500, which are intended to symbolize an application of a vibration pressure in direction x3(in arrow directions of x3) and in the opposite direction x3(opposed to the arrow direction of x3). The surfaces of the grooves15,35and webs14,34are pressed onto one another and vibrated by the vibration pressure such that the assembly regions12,13, which are in engagement, of the first layer10and of the second layer30are surface-fused, so that both assembly regions12,33are connected with one another permanently. A predetermined vibration pressure is preferably applied in a frequency range of 85 Hz on the assembly regions12and33.

Other fastening and joining methods can also be used for fastening the first layer10on the second layer20. The following are named here in addition, by way of example: ultrasonic welding, heated tool welding, infra-red welding, hot gas welding, spot welding, friction welding, high frequency welding, circular welding or laser beam welding. In particular, fastening methods are able to be used which are suitable for the permanent connecting of the first and second layer10,30, in which the plastics and materials used of the two layers10,30are not negatively impaired.

As can be seen fromFIG. 9, the first layer10and the second layer10,30are now fastened to one another by the previously applied joining or fastening method, and already the detachable and non-destructive dismantling of the fastening strip70from the first layer10and the eliminating of the protective cap200has begun, as indicated by the arrows300. It is important here that both the fastening strip70and also the protective cap200have been mounted on the first layer10such that they cannot become detached during the fastening method which is used, and nevertheless can be eliminated from the first layer10in a non-destructive manner, as indicated inFIG. 9.

InFIG. 10the interior panel part1is illustrated in its final state. The fastening strip70is fastened to the reinforcing ribs31. Ultrasonic riveting is regarded here as the preferred fastening method. The fastening strip70can, however, also be fastened by screw connections or other fastening methods, such as gluing, screwing and/or welding methods, on the lower side30aof the second layer30. The plug connection71and the plug mount device16can be eliminated, as illustrated inFIG. 10, in which these are correspondingly separated or filled.

FIGS. 11 and 12show in a simplified bottom view of the airbag cover region20diagrammatically possible embodiments of the coupling device or respectively plug mount device16of the first layer10, which can be formed in the cover region lower side10aof the first layer10, wherein the different embodiments are illustrated separated from one another according toFIGS. 11 and 12by the reference line B-B in mirror image. InFIG. 11, as a first embodiment the plug mount device16is illustrated as a plurality of recesses with a circular opening edge. The recesses are arranged parallel to one another and in series. On the opposite side of the reference line B-B a second embodiment of the plug mount16is illustrated, which is formed by channels or grooves arranged parallel to one another.

InFIG. 12the plug mounts shown inFIG. 11are arranged offset with respect to one another.

The embodiments of the plug mount device16illustrated inFIGS. 11 and 12are designed such that the plug devices71provided on the fastening strip70can be retained for example by the action of a press fit therein. For this, either the elements of the plug devices71have a slight excess, or the elements of the plug mount device16of the associated plug devices71have a slight undersize, or vice versa The distribution of the elements of the plug mount device16, illustrated in the bottom view, in the first layer10is constructed in a manner corresponding to the distribution of the elements of the plug devices71of the fastening strip70. In another embodiment of the interior panel part1according to the invention, the elements of the plug device71of the fastening strip70can be formed on the first layer10, wherein the corresponding elements of the plug mount device16in this case are provided on the fastening strip70.

A preferred method for the production of the interior panel part1, shown inFIG. 2, is described below with reference toFIGS. 3 to 10.

As shown inFIG. 3, the flexible connecting part40is inserted into an opened mold80in the correct position. The mold parts81,82,83of the mold80are then closed such that the cavities are produced for forming the first layer10and the fastening strip70. When the cavities are properly formed, plastic is injected into the cavities, wherein the final state of the injection step is illustrated inFIG. 4. The first layer10and the fastening strip70can also be formed in separate injection processes, wherein preferably firstly the fastening strip70and thereafter the first layer10are injected onto the flexible connecting part40. After the injection step, the flexible connecting part40together with the first layer10and the fastening strip70is removed from the mold80. Then, as illustrated inFIGS. 5 and 6, the fastening strip70is mounted detachably by means of its plug device71on the first layer10in the plug mount devices16thereof. In the next step, a protective cap200is mounted over the region of the fastening strip70which is mounted on the first layer10. Before or after the mounting of the protective cap200, the first layer10can be provided with a material weakening13at the sites indicated inFIGS. 1 and 2. A material weakening13means here the reduction in the rigidity by the removal of material, so that at the site of the material weakening the airbag cover can be torn open by an expanding airbag. Preferably, the material weakening takes place in a laser method.

After the assembling of the fastening strip70and of the protective cap200on the first layer10, the mounting of the second layer20onto the first layer10takes place. The second layer20was previously produced here in a similar injection molding or pressing method and prepared for the permanent connection with the first layer10. Then the two layers10,20are arranged one over another such that the assembly regions12,33of the first layer10or respectively of the second layer30are in engagement with one another in an accurately fitting manner, as shown inFIGS. 7 and 8. Then by applying a vibration pressure with approximately 85 Hz, a vibration welding step is carried out, in order to fasten the assembly regions12,33with one another. However, other fastening and joining methods are also able to be used, such as for example: ultrasonic welding, heated tool welding, infra-red welding, hot gas welding, spot welding, friction welding, high frequency welding, circular welding and/or laser beam welding. For fastening the assembly regions12,33of the first layer10or respectively of the second layer30, joining methods are preferred which are suitable for the permanent connecting of plastics.

After the fastening of the first layer10on the second layer30, the protective cap200is eliminated and the fastening strip70is brought out of engagement from the first layer10, in which the plug devices17of the fastening strip are detached in a non-destructive manner from the plug mount devices16of the first layer10. Finally, the fastening strip70at the position illustrated inFIG. 10on the margin region32is mounted on one or on both reinforcing ribs31of the second layer20by ultrasonic riveting. The fastening of the fastening strip70on the second layer20can also take place by a different fastening and joining method, such as gluing, welding or by screw connections.

After this, a decorative layer can be applied on the interior panel part1, illustrated inFIG. 10, on the first layer10. The decorative layer can be a layer of a knitted fabric or foam, on which a leather or slush skin can be provided.