DE102014104906A1 - Cover for an airbag with a decorative layer of leather and method of its manufacture - Google Patents

Abstract

The invention relates to an airbag cover (10), in particular for use in motor vehicles, with a decorative layer (11) made of leather, wherein the leather on the leather back (12) split down to a constant thickness d of less than 0.6 mm and on the leather back (12) a soft leveling layer (13) is glued, wherein the leveling layer (13) does not or only insignificantly influences the breaking strength of the leather and the leveling layer (13) is not weakened.

Description

The invention relates to an airbag cover, in particular for use in motor vehicles, with a decorative layer of leather and a method of their production.

Airbags are nowadays integrated in motor vehicles in various places, for example in steering wheels, dashboards, doors, seats, roof cladding, etc. For a reliable functioning of the airbag, it is necessary for the plastic carrier in all its layers to have one or more material weakenings, so-called predetermined breaking points, which define the firing channel of the airbag.

In the area of the covers of an airbag, it is customary - especially with the material leather - to provide the cover of the airbag in the area of the airbag flap with a so-called airbag documentation seam, so that it can open unhindered in the event of an impact and the airbag can deploy.

For optical reasons or because of the design, however, motor vehicle manufacturers are increasingly demanding that, for example, the front passenger airbag, which is integrated in the dashboard, be made invisible on the side facing the occupant. For this purpose, the dashboard is provided with the integrated airbag flap with a coating without airbag documentation seam. However, in the region of the edge of the airbag flap, this coating must also have a material weakening, so that the secure opening of the airbag flap and the deployment of the airbag in the event of an impact remain ensured.

The opening of the coating along the material weakenings must also occur within a given time window. Similarly, an uncontrolled particle flight by flying fragments of the coating must be avoided in any case.

Such airbag cover coatings are known from different materials, for example, plastic films, fabrics, textiles, slush, imitation leather or leather. Especially with upscale vehicle equipment coatings are increasingly made of leather. Leather has no homogeneous material properties and has in its grown three-dimensional fiber structure an extremely high strength, making leather particularly strong material weakening required to even allow unhindered deployment of the airbag.

These functional requirements, while complying with the "Invisibility" design specification, represent a major technical challenge, which, especially with regard to the material leather, has to be classified as technically very demanding.

In order to achieve an effective rupture with appealing optical design, was in the DE 101 26 911 A1 proposed to provide multiple cut lines on the inside of the cover, through which a reliable and defined crack formation along the predetermined breaking line without uncontrolled particle flight can be achieved even at low temperatures. In order to obtain an attractive surface, the incisions should in any case have a cutting depth consistently below the wall thickness of the decorative skin, so that the residual wall thickness of the material is maintained.

However, weakening of the coating material by scoring have the disadvantage that the notch at a deep incision aufklafft and thus the notch on the visible side of the coating over time by the temperature changes, which is subjected to the coating in the motor vehicle, visible. At lower cutting depths, the tearing behavior is negatively influenced.

In the EP 1 213 193 A1 It is proposed to perforate the airbag cover in the region of the edge of the airbag case cover and then refill with a suitable filler to conceal the openings on the visible side. In this way, although it can be achieved that the perforations are no longer recognized by the vehicle occupants, but this process is complex, since the leather must be returned to the leather supplier after the introduction of the perforations.

In order to provide the vehicle occupants invisible airbag coverings with controlled tearing behavior, proposes the DE 100 55 546 A1 before, along a predetermined breaking line extending weakening structures to produce, wherein the weakening structures are produced by means of a punching tool on the material inside recesses. By suitable choice of the sequence and depth of the recesses, the desired tear-open behavior is to be achieved in the case of undamaged outer side of the cover pointing in the direction of the vehicle interior, whereby in this method, in turn, a residual wall thickness of the material is maintained.

Even if the desired tear behavior is achieved with this coating and the outwardly facing surface of the cover as "residual wall" remains intact, so that no unwanted, visible to the outside cuts are visible, even these covers do not meet the required invisibility, as again the cuts under Temperature influence open up and thus become visible on the visible side of the coating.

Especially with the natural leather material, the required invisibility by means of the described methodology can not be guaranteed even below room temperature, since in the course of the punching process the leather fibers are heavily compressed and compressed. Due to this "leather-unfriendly" material treatment, the leather has visible greasy shiny areas on the visible side.

Furthermore, it is known to weaken the coating by means of a laser process. Difficulties occur in the laser-based method, however, because the desired invisibility of the weakening, especially in light-colored leather, can not be guaranteed. Also, such laser-weakened materials in shot tests - probably because of the hardening in the edge regions of the generated weakenings caused by the high-energy radiation - led to excessive opening times.

The DE 102 31 131 A1 teaches an airbag cover having a first intact layer of leather and a second layer of fabric, film or nonwoven facing the folded airbag, the second layer being attached to the back of the first layer to reinforce the second layer Layer for reinforcing the first layer has a weakened area. To improve the feel, a third layer may be attached to the second layer, which is constructed of a spacer knit, foam or a combination of spacer knit / foam. The third layer may also have an auxiliary attenuation region.

However, such a cover does not show the desired defined tear behavior, and it also comes in part to unwanted particle flight.

From the EP 1 745 989 A1 there is known an airbag cover having a leather viewing cover having a partial weakening wherein the transition between weakened area and non-weakened area in the leather is continuous, and a second layer below the viewing cover that is softer than that below the second layer Molding is. For the steady transition between the weakened and the non-weakened region, the visual coverage in cross-section describes a curve that is monotonically increasing or monotonically decreasing in the region of the transitions. Such an airbag cover is complex to manufacture and a deviation from the desired geometry is accepted purchase, since was removed at the areas of continuous weakening material.

From the EP 2 077 208 an airbag cover is known, wherein in the bottom of a decorative layer of leather weakening with a laser is introduced and the leather is then split, to remove incrustations that are caused by the burn-in of laser perforations. The leather thus treated is then applied to a piece structure. This is intended to avoid unwanted beads along the line of weakness long term.

The object of the present invention is to provide an airbag cover with a non-visible airbag passage opening, which is easy to manufacture and can be largely dispensed with the complex positioning of the weakening of the leather with respect to the airbag flap and their control and documentation.

This object is achieved in that in the airbag cover according to the invention, the entire leather on the leather back down to a constant thickness of less than 0.6 mm and glued to the leather back a soft leveling layer, wherein the leveling layer is not the tearing force of the leather or only insignificantly influenced and the leveling layer is not weakened.

Due to the flat weakening of the entire leather back can be largely dispensed with the complex positioning of the weakening of the leather with respect to the airbag flap and their control and documentation.

Due to the omission of the specific weakening geometry and the displacement of the weakening in a planar structure, the recognizability of an opening edge of the airbag flap is further reduced.

The fact that the leather, which generally has a wall thickness of about 1.3 mm, is split down to a thickness of less than 0, 6 mm, reduces the breaking strength and the elongation at break, so that no further weakening of the leather is required. The down splitting of the leather can by a suitable device, as for example in the DE 39 22 756 C2 is described, done.

In order to be able to process these thin leather blanks satisfactorily, a leveling layer is glued onto the thin leather, so that the leather can be sewn and laminated. The Leveling layer has no weakening and must be such that it does not or only slightly influences the breaking forces. It should have a tactile pleasant appearance and at the same time can take over the necessary stiffening at the seam areas.

Since the leather is split down to a constant layer thickness, a simple production is possible. Preferably, the leather is split down to a layer thickness of 0.15 mm to 0.6 mm, and more preferably from 0.35 mm to 0.5 mm.

Preferably, the leveling layer is made of a material that is soft or feels soft, i. has a hardness of not more than 40 Shore A, but ruptures on sudden stress. The leveling layer is particularly preferably a cut foam or a fleece, in particular a PU, PE, PVC foam, a PU cut foam or nonwoven. The layer thickness of the compensating layer should be at least 0.2 mm and at most 5 mm, preferably at least 0.5 mm and at most 4 mm. Preferably, the layer thickness of the leveling layer over the entire surface of the decorative material is constant and a direct application of the foam instead of laminating possible.

In a further variant, the compensation layer in the overlapping region of the flap, with the exception of the tear region, in some areas reinforcements which extend, for example, circumferentially around the exit region of the airbag and thus can control a targeted tearing in the region of the exit region. These can be, for example, jersey, fabric, mesh or fleece.

By means of the leveling layer, a correspondingly softer feel can be set. In addition, for the leveling layer, a material of low density can be used as leather, which can lead to a weight saving.

With the leveling layer, the leather composite consisting of leather and the compensating layer can also be reinforced in order to selectively adjust the tearing properties in the airbag area with a stiffness difference, firstly by masking or by reinforcing the edge region of the opening region of the airbag. On the other hand, the reinforcement can also be adjusted by laminating a thin textile or a polymer entry, as is the case when reinforcing a seam with a textile band.

In addition, the reinforcement of the leveling layer during foaming (soft component) on a textile (reinforcement) or the foaming of the leveling layer with / without reinforcing fleece directly on the leather.

In a further variant, a haptic layer is provided below the compensating layer, which is less soft than the compensating layer. As a result, an airbag can be provided with a very pleasant two-stage feel, the leather feels very soft on the initial pressure, with increasing pressure it becomes slightly harder until the upper materials are completely pressed onto the wearer.

The thickness of the haptic layer should preferably be constant throughout the airbag cover and should be between about 0.8 mm and 10.0 mm and preferably between 1.3 mm and 8.5 mm.

The haptic layer may be made of spacer fabric or PUR foam, for example.

If desired, the haptic layer can be partially weakened, for example, by cuts. However, this is not required, especially in a tear-friendly biaxial spacer fabric.

It is also possible to apply the coating of the haptic layer with foam in the direct order and then to laminate the leather.

In the airbag cover according to the invention, a layer on the meat side of the leather is removed and replaced by a lighter, good-tear layer with greater softness than leather. As a result, both good tearing properties, and a softer feel than leather, as well as a lighter and more elastic airbag cover are obtained.

Another advantage of the airbag cover according to the invention is its ease of manufacture, since neither special weakenings are required, nor an accurate positioning.

The support is normally made of a rigid and heat-resistant material, e.g. PP GF20-30, PUR-GF, PP-talcum, carbon (CFRP), PP-GF or SAM GF15, ABS PC and is harder than the above arranged haptic layer.

The invention also relates to a method for producing the airbag cover according to the invention, in which first leather on the leather back is split down to a constant layer thickness of less than 0.6 mm and then adhered to the leather back a soft leveling layer and optionally Subsequently, a haptic layer is laminated on the back of the leveling layer, which in turn is laminated with its back on the support.

The invention will be described in more detail with reference to an embodiment.

It shows:

1 a section through an airbag cover according to the invention

2 : A plan view of an airbag cover 10 with reinforcement in the edge area of the exit area.

The airbag cover 10 includes a decorative layer 11 made of leather, with the leather on its back 12 is split down to a maximum layer thickness d of 0.6 mm.

The split-down can be done for example by a splitting machine.

On the back side 12 is a balancing layer 13 made of fleece or foam laminated. The layer thickness of the leveling layer 13 is between 0.5 mm and 5 mm and preferably between 0.3 mm and 0.7 mm.

Below the leveling layer 13 can be a haptic layer 14 be provided, for example, a spacer knitted fabric or foam .. The thickness of the haptic layer 14 is between 0.5 mm and 5.5 mm and preferably between 1.0 mm and 3.7 mm

The backside 15 the haptic layer 14 is on the rigid carrier 16 , For example, an instrument panel with an integrated airbag flap (not shown), glued. The carrier has a weakening (not shown). The haptic layer 14 can, but need not, be weakened 18 , for example an incision.

In a further variant, the airbag cover 10 in the edge area of the exit area 19 reinforced of the airbag, for example by a lamination 20 with a thin textile or by polymer entry, as shown schematically in the 2 shown.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10126911 A1 [0008]
• EP 1213193 A1 [0010]
• DE 10055546 A1 [0011]
• DE 10231131 A1 [0015]
• EP 1745989 A1 [0017]
• EP 2077208 [0018]
• DE 3922756 C2 [0023]

Claims (10)

Airbag cover ( 10 ), in particular for use in motor vehicles, with a decorative layer ( 11 ) made of leather, the leather on the back of the leather ( 12 ) down to a constant thickness d of less than 0.6 mm and on the leather back ( 12 ) a soft leveling layer ( 13 ), the leveling layer ( 13 ) the tear strength of the leather is not or only insignificantly influenced and the leveling layer ( 13 ) is not weakened. Airbag cover according to claim 1, characterized in that the compensating layer ( 13 ) is made of a soft material having a maximum hardness of 50 Shore A, and ruptures on sudden stress. Airbag cover according to claim 1 or 2, characterized in that the compensating layer ( 13 ) is a cut foam or a nonwoven. Airbag cover according to one of the preceding claims, characterized in that the thickness of the compensating layer ( 13 ) is between 0.2 mm and 5.0 mm. Airbag cover according to one of the preceding claims, characterized in that the thickness of the compensating layer ( 13 ) is constant over the entire area of the airbag cover. Airbag cover according to one of claims 1 to 4, characterized in that the compensating layer ( 13 ) is reinforced in certain areas, in particular around the outlet opening for the airbag. Airbag cover according to one of the preceding claims, characterized in that the thickness of the decorative layer ( 11 ) is constant over the entire area of the airbag cover. Airbag cover according to one of the preceding claims, characterized in that the haptic layer ( 14 ) less soft than the leveling layer ( 13 ). Method for producing an airbag cover according to one of the preceding claims, characterized in that the leather on the back of the leather ( 12 ) down to a constant thickness of less than 0.6 mm, then on the leather back ( 12 ) a soft leveling layer ( 13 ) and possibly on the back of the leveling layer ( 13 ) a haptic layer ( 14 ) is glued. Method according to claim 9, characterized in that the compensating layer 1 ( 13 ) directly on the leather back ( 12 ) or the haptic layer ( 14 ) is applied.

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