WO2013182375A1

WO2013182375A1 - Airbag cover

Info

Publication number: WO2013182375A1
Application number: PCT/EP2013/059718
Authority: WO
Inventors: Michael Walter; Luc Burgard; Wolfgang Oestreicher; Matthias Rech; Sebastian Wandtke
Original assignee: Faurecia Innenraum Systeme Gmbh
Priority date: 2012-06-07
Filing date: 2013-05-10
Publication date: 2013-12-12
Also published as: DE102012209609A1

Abstract

Disclosed is an airbag cover (1) comprising a decorative layer (2), which seals off the airbag cover (1) to a vehicle interior, and a haptic layer (5), which is arranged on a side of the decorative layer (2) that faces away from the vehicle interior, the haptic layer (5) being entirely or at least partially formed from a dilatant material. Also disclosed is an airbag device comprising an airbag (8), a gas generator (10) and an airbag cover of the proposed kind.

Description

Airbag cover

The present invention relates to an Alrbagabdeckung according to the preamble of the main claim and an airbag device.

Airbag devices with covers for an airbag are used in interior parts of vehicles, eg. As in instrument panels, steering wheels, door panels, seats, rear shelves, etc. integrated to one or more contained in these innenverkietdungung parts airbags in the unfolded state, ie in the normal state, to hide. This also serves to protect the airbag (s) from damage by vehicle occupants. At the same time, in the event of deployment of the airbag, airbag devices should ensure that the airbag can deploy in a desired direction quickly enough without compromising vehicle occupants by sharp edges of the atrial cover or the like.

Such airbag devices are already known from the prior art. In general, an interior trim panel known as the

Airbag cover is formed and facing a vehicle interior, on its side facing away from the vehicle interior during the production process is weakened so that a reliable, reproducible and defined opening of the interior trim part and thus the

Airbag device is achieved in the case of an unfolding airbag. A defined opening of the interior trim part is understood to mean an opening along a tear line of an airbag flap, in which the airbag flap opens such that the unfolding airbag can deploy as desired and without obstacles in a firing channel into the vehicle interior.

In particular, when leather is used as a material for the InnenverkleidungsteÜ, for local weaknesses by perforating, cutting or downsplitting usually a complex and expensive mechanism is necessary, which also requires a considerable adjustment effort, or there is a risk that introduced weakening with increasing aging of the leather become visible over time and thus the optical appearance of the airbag cover decreases significantly.

The present invention is therefore the object of a

To develop airbag cover that avoids the disadvantages mentioned, in which therefore can be dispensed with in the manufacturing process to a costly weakening of Dekorbag contained in the Arrbagabdeckung, but still a reliable opening of the airbag cover when the airbag is triggered.

This object is achieved by an airbag cover with the features of the main claim. Advantageous embodiments and further developments are described in the dependent claims.

So proposed is an airbag cover, which includes a decorative layer and a haptic layer. The decorative layer closes the

Airbag cover to a vehicle interior down and the haptic layer is disposed on a side facing away from the vehicle interior side of the decorative layer. The haptic layer is wholly or at least partially from one dilatant material formed. Instead of an airbag cover, the article proposed here may also be any desired inner recessed part.

The dilatant material is a mattress whose viscosity and / or strength and / or stiffness increases when shear forces act on the dilatant material and / or when the material is deformed. Usually, the viscosity and / or strength and / or stiffness of the dilatant material increases with increasing shear rate, preferably more than linearly. Ideally, the dilatant material is designed to be soft in a non-deformed or slightly deformed state.

On the other hand, the strength, hardness or rigidity of the dilatant material may greatly increase due to sudden deformation. The term dilatancy is also referred to as shear thinning or shear hardening. When no shear forces act on the haptic layer, the viscosity and / or elastic modulus and / or compressive strength and / or shear strength and / or stiffness of the haptic layer or at least a portion of the haptic layer containing the dilatant material are each defined by a first one Value given the appropriate size. The first value of the modulus of elasticity of the haptic layer may be at 20 ° C z. 8. between 0.001 and 0.2 GPa are (for comparison: polyurethane foam has an E-modulus of about 0.06 GPa). As a result of a triggering of the airbag, which is arranged below or behind the haptic layer before being released from the vehicle interior, within one deformation period an energy envelope is deposited completely or at least partially in the haptic layer or transferred thereto, whereby the haptic layer at least partially is deformed. During the deformation period, therefore, a deformation force acts at least partially on the haptic layer. As a result, the viscosity and / or the modulus of elasticity and / or the compressive strength and / or the shear strength and / or the stiffness of the haptic layer can increase at least in some areas and in each case assume a second value. The second values are each one factor larger than the corresponding first values. In this case, the haptic layer is typically formed in a planar manner and the airbag preferably strikes the haptic layer or a deformation region of the haptic layer upon release, in that an impulse of the airbag with a surface normal of the haptic layer includes an angle of incidence which is less than 20 °, less than 15 °, less than 10 ° or less than 5 °.

The deformation time may be less than 0.05 seconds, less than 0.03 seconds, or less than 0.01 seconds. The amount of energy can be greater than 1 kJ, greater than 2 kj, greater than 3 kl or greater than 5 kl. Instead of the amount of energy that within the deformation period at least partially in the

Haptikschicht is deposited or transferred to this, an airbag energy may be given, which releases a gas generator when the airbag is triggered. The said amount of energy is then usually part of and smaller than the airbag energy. The Airbagenergie can also be greater than 1 kl, greater than 2 kJ, greater than 3 kJ, greater than 5 kJ or greater than 10 kl. The deformation force can be greater than 1 kN, greater than 3 kN, greater than 5 kN or greater than 10 kN. At the same time or alternatively, the deformation force can not be more than 15 kN. The deformation region of the haptic layer, to which the amount of energy or the airbag energy during deformation is transmitted wholly or at least partially and / or on which the deformation force acts during deformation, can have a cross section which is greater than 50 cm ¹ perpendicular to the weft direction of the airbag greater than 100 cm ² , greater than 200 cm ² or greater than 400 cm ² . A pressure exerted at least partially on the haptic layer during the deformation period can thus be greater than 10 ⁵ N / m ² or greater than 10 ⁶ N / m ² . The factor by which the above second values are greater than the corresponding first values may be greater than 10, greater than 20, greater than 50, greater than 100, or greater than 500.

The dilatant material may be, for example, hydroterminated

Polydimethylsiloxane, in particular hydroterminated dimethylsiloxane include. An example of a known dilatant material is "Dow ^Corning® 3179 dilatant compound", which is 65% dimethylsiloxane, 17% crystalline

Silica, 9% Thixotrol ST, 4% Polydimethylsiloxane, 1%

Decamethylcyclopentasiloxan, 1% glycerol and 1% titanium dioxide, wherein the amounts are given in each case in percent by weight. Another example is a material from Design Blue Ltd. (d3o technology) according to the published US 2007/0029690 AI or US 2010/0132099 AI. Due to the fact that the haptic layer is formed wholly or at least partially from the dilatant material, the haptic layer, in a state in which no or only small shearing forces act on the haptic layer or in which the haptic layer is not or only slightly deformed, has a haptic layer. lend vehicles the desired soft feel. If the airbag is activated in the event of an impact of the vehicle on an obstacle and the airbag transfers the amount of energy or the airbag energy wholly or at least partially to the haptic layer within the deformation period, the viscosity and / or the compressive strength and / or the tensile strength and / or the Stiffness of the haptic layer at least partially abruptly as described above.

In the state of the haptic layer that is at least partially hardened or solidified in this way, the haptic layer does not absorb the amount of energy or the airbag energy or only to a very small extent. The

Haptikschicht is set up to transfer the amount of energy or Airbagenergie or the deformation force particularly efficient on the decorative layer, so that the decorative layer particularly easy at least partially ruptures or is severed. The airbag can thus easily pierce or at least partially open the airbag cover, in particular the decorative layer, and unfold into the vehicle interior.

In contrast, in known from the prior art interior trim parts, which are used as airbag covers, the soft haptic often absorbs a significant portion of the amount of energy or airbag energy when the airbag is triggered, so that it is necessary to mechanically weaken the decorative layer at least partially, what with connected to the disadvantages described above. Due to the considerably more efficient transfer of the amount of energy or the airbag energy to the decorative layer in the airbag cover proposed here, a mechanical weakening of the decorative layer, on the other hand, can be completely eliminated. The manufacture of the airbag cover can thereby be considerably simplified and production costs can be greatly reduced. In addition, with an aging of the decorative layer, no visible changes of the decorative layer occur, as is the case with mechanically weakened elements known from the prior art

Decorative layers are observable. The improved transfer of energy or force from the haptic layer to the decorative layer can be realized above all by the fact that at least a region of the haptic layer which forms part of an airbag flap of the

Airbag cover forms, wholly or at least partially formed from the dilatant material or contains the dilatant material, wherein the

Airbag flap is set to be opened at least partially by the airbag at a release of the airbag and release a firing channel for the airbag. The airbag flap should therefore preferably denote that part of the interior trim part or the airbag cover which moves when the airbag is triggered by the airbag, ie is opened or punctured. The airbag flap thus typically comprises at least those parts of the decorative layer and the haptic layer that lie in the firing channel of the airbag. This area of the haptic layer is then at least partially hardened by the deformation and thus transfers the amount of energy or the airbag energy to the decorative layer in a particularly efficient manner.

In a specific embodiment, the haptic layer may be formed at least partially as a film. Such a film is particularly easy to work with and has a low weight. A thickness of the film may be less than 3 mm, less than 1 mm or less than 0.5 mm. The

Haptic layer may also be formed as a composite with a foamed polymer layer, wherein the dilatant material is then integrated into the foamed polymer layer. The foamed polymer layer may, for. Foamed polyurethane, polyethylene (PE), polystyrene (PS),

Plyethylene terephthalate (PET) or polypropylene (PP) included. Such foamed polymers give the haptic layer particularly advantageous haptic properties.

The decorative layer and the haptic layer can be joined directly to one another. The breaking, puncturing or tearing the

Decorative layer necessary force or energy is thereby particularly efficiently transferred from the haptic layer on the decorative layer when the airbag. In order to achieve the most efficient energy or force transfer so preferably no energy-absorbing layers between the decorative layer and the haptic layer are arranged. However, the decorative layer and the haptic layer can be glued, laminated, welded or laminated on each other. Typical weisse is between the decorative layer and the haptic layer so only one Fügeschicht, z. As an adhesive layer, arranged, wherein the thickness of this joining layer is then preferably less than 1 mm, less than 0.5 mm or less than 0.2 mm.

The haptic layer may be at least partially weakened mechanically. The opening or piercing of the airbag cover by the airbag can be facilitated thereby. By way of example, the weakening can be realized in that the thickness of the haptic layer is reduced in regions and / or that the haptic layer has aterial recesses in regions and / or is perforated. The weakening can be within the

Haptic layer be formed like a line or area. The weakening can also be realized in that the haptic z. B. along a line-like portion completely or at least partially incised and joined along the incision only partially. The weakening of the haptic layer typically defines the area of the

Haptic layer, which is part of the airbag flap.

The haptic layer may have a thickness of less than 10 mm, less than 5 mm or less than 3 mm. In this case, the haptic layer is therefore particularly material-saving and thus cost-effective. In addition, it can be processed very easily during production.

In a specific embodiment, the airbag cover may have a carrier layer, wherein the haptic layer is then arranged between the carrier layer and the decorative layer. This gives the airbag cover a high mechanical stability. Typically, the carrier is wholly or at least partially formed from a plastic, e.g. B. off

Polypropylene. The thickness of the support may also be less than 10 mm, less than 5 mm or less than 3 mm.

The carrier layer may also be mechanically weakened, at least in some areas. In other words, the carrier layer may also have at least partially a mechanical weakening. The mechanical weakening of the carrier layer can be realized in the same way as the mechanical weakening of the haptic, so z. B. by a partial reduction in the thickness of the carrier layer, by material recesses or by partial perforation of the carrier layer. The weakening the carrier layer preferably defines a portion of the carrier layer which is part of the airbag flap. The opening of the airbag flap when the airbag is triggered is thereby facilitated.

The decorative layer is preferably made of leather, a polyvinyl chloride skin (PVC skin) or a skin made of thermoplastic polyolefins (TPO skin) or comprises at least these materials. The materials mentioned are common for decorative layers of interior trim parts and of

Airbag covers.

Also proposed is an airbag device comprising the previously described airbag cover. The airbag device includes besides the

Airbag cover also the airbag and a gas generator, wherein the inflator and the airbag are disposed in a non-activated state of the airbag on a side facing away from the vehicle interior side of the airbag cover and wherein the inflator is configured to inflate the airbag such that the inflated airbag pierces the airbag cover and deployed in the vehicle interior.

Embodiments of the invention are illustrated in the drawings and will be explained with reference to Figures 1 to 5.

Show it:

Fig. 1 is a plan view of an interior trim part in the form of a

Airbag cover;

Fig. 2 is a Fig. 1 corresponding view of another Ausfüh

form of an airbag cover;

3 is a sectional view of the airbag cover;

FIG. 4a shows a cross-section of the haptic layer along a plane shown in FIG. 3; FIG.

4b shows the cross-section of the haptic layer from FIG. 4b according to a variant of FIG. converted embodiment;

Fig. 5a schematically shows a time course of a force that at a

Triggering of the airbag is exerted on a haptic layer of dilatant material;

5b schematically shows a time profile of a modulus of elasticity of the haptic layer, the modulus of elasticity increasing as a result of the force shown in FIG. 6a; and

Fig. 6 is a sectional view of the airbag cover shown in Fig. 4 with unfolded airbag.

In Fig. 1 is a plan view of an interior trim part in the form of a

Airbag cover 1 shown in a vehicle interior. From this side, only a decorative layer 2 of the airbag cover 1 is visible, which consists of a dermis in the illustrated embodiment and which closes the airbag cover 1 to the vehicle interior. Instead of the dermis, a PVC skin or a TPO skin can also be used in further embodiments. The decorative layer 2 has over its entire surface a constant thickness without prior or introduced during a manufacturing process weakening.

In the embodiment shown in Fig. 1, the airbag flap consists of two wings 4a and 4b, which are defined by dashed lines shown tear lines. Perforations 12 are formed along the tear lines at least within a haptic layer 5 and within a carrier 6 (see FIGS. 3, 4a, 4b). If the airbag 8 unfolds in the event of a collision of the vehicle in the direction of the vehicle interior, the wings 4a and 4b fold into the vehicle interior (FIG. 6).

2, a further embodiment of the airbag cover 1 is shown in a view corresponding to FIG. 1. Recurring features are provided with identical reference numerals in this as well as in the following figures. The airbag flap has in this embodiment, only one wing 4, which in its dimensions by the here "U" -shaped course which in turn is defined by dashed lines shown tear line.

Fig. 3 shows the airbag cover 1 in a sectional view. From this view, it is clear that the airbag cover 1 is composed of several superimposed layers. As the uppermost layer, which faces the vehicle occupant, the decorative layer 2 is applied. Facing away from the decorative layer 2 and the vehicle interior is a haptic layer 5. The haptic layer 5 is here a film which is formed from dimethylsiloxane and thus has a dilatant behavior. In particular, the viscosity and / or the strength and / or rigidity of the haptic layer 5 increase when it is deformed under the action of a deformation force. The thickness 14 of the haptic layer 5 is 2 mm here. In an alternative embodiment, the dilatant haptic layer 5 z. Example, be given in the form of a composite, which is a foamed polymer layer, for. B. polyurethane foam contains. The dilatant material is then integrated into the foamed polymer layer. Here, the entire haptic layer 5 is formed from the dilatant material. In alternative embodiments, only a portion of the haptic layer 5, which forms part of the airbag flap and which lies in a firing channel 11 of the airbag 8, may be formed entirely or at least partially from the dilatant material.

The haptic layer 5 and the leather decorative layer 2 are joined directly to one another and connected by an adhesive layer not explicitly shown here, but whose thickness is smaller than 0.2 mm. This is to ensure that a upon deployment of the airbag 8 from the airbag 8 on the

Haptikschicht 5 applied force is efficiently transferred to the decorative layer 2, so that the decorative layer 2 at least partially ruptures. In particular, it should be avoided as much as possible that further layers arranged between the haptic layer 5 and the decorative layer 2 absorb the force required to rupture or open the decorative layer 2 and thus reduce it. In alternative embodiments, the

Decorative layer 2 and the haptic layer 5 z. B. also at least partially welded together, laminated, laminated or joined together in any other way.

As the lowermost layer, the airbag cover 1 has a polypropylene carrier 6 on, among other things, responsible for the mechanical stability of the airbag cover 1. Also with this the haptic layer 5 is connected by means of an adhesive layer, not shown here. The haptic layer 5 is thus arranged between the carrier 6 and the decorative layer 2.

Below the carrier 6, the airbag 8 is arranged in a bracket 9 connected to the holder 9. In the event of an accident, the airbag 8 is inflated explosively by a gas generator 10 and unfolds along the crossed-out arrows in the firing channel 11 in the direction of the decorative layer 2 and the vehicle interior away from the gas generator 10 until the airbag 8 indicated by the dashed line inflated State has reached. The airbag cover 1, the inflator 10 and the airbag 8 are part of an airbag device.

In order to facilitate the opening of the airbag cover 1 upon deployment of the airbag 8, the dilatant haptic layer 5 and the carrier 6 are along the in Figs. 1 and 2 are partially perforated by the perforations 12 shown in FIG. The perforations 12 formed along the tear lines thus define an airbag flap which comprises those regions of the carrier 6, the haptic layer 5 and the decorative layer 2 which are pierced or opened by the airbag 8 in the event of triggering of the airbag 8 and thus release the firing channel 11 , The firing channel 11 then passes through the carrier layer 6, the haptic layer 5 and the decorative layer 2.

FIG. 4a shows a cross-section of the haptic layer 5 along the section plane 20 shown in FIG. 3. It can be seen that the perforations 12 define a region 4 'of the haptic layer 5 which forms part of the regions shown in FIGS. 1 and 2, the airbag flap shown. The region 4 'also defines a cross-section of the weft channel 11. A length 21 and a width 22 of the region 4' are each 15 cm. The tear lines within the haptic layer 5 given by the perforations 12 thus have a length of 45 cm and the area 4 'an area of 225 cm ² . The mechanical weakening of the

Haptic layer 5 in the form of the perforations 12 causes the region 4 'of the haptic layer 5 is mechanically decoupled from the remaining region 4 "of Haptikschicht 5 in such a way that when triggered the airbag 8 substantially only the area 4' of the Haptikschicht 5 deformed will and the Haptikschicht 5 breaks along the tears defined by the perforations 12 breaks or tears.

In the case of the embodiment of the haptic layer 5 shown in FIG. 4a, this is completely formed from the dilatant material. In contrast, FIG. 4b shows an alternative embodiment of the haptic layer 5. In this embodiment, the haptic layer 5 has no mechanical weakenings. However, here not the entire haptic layer 5 is formed from the dilatant material, but only the area 4 ^f . The remaining area 4 "of the haptic layer is formed of a material which has no dilatant behavior.

B. desirable to reduce material costs. As a result of the different material properties of the regions 4 'and 4 "of the haptic layer 5, similar to the embodiment shown in FIG. 4 a, when the airbag 8 is triggered, a mechanical decoupling of the regions 4' and 4" occurs, since only the dilatant region 4 'hardened. Along the boundary line 23, which separates the dilatant region 4 'from the non-dilatant region 4 ", a break or tear of the haptic layer 5 occurs when the airbag 8 is triggered. The dimensions of the region 4' in FIG. 4b are identical to those in Fig. 4a.

The properties of the dilatant haptic layer 5 are based on the in FIGS. 5a and 5b illustrated diagrams. FIG. 5 a schematically shows a chronological progression 18 of the absolute value F of a force 15 exerted on the haptic layer 5 by the airbag 8 when the airbag 8 is triggered via the carrier 6 (see FIG. 3). The force 15 is directed from the gas generator 10 to the airbag cover 1 and the vehicle interior and acts approximately parallel to a surface normal 16 (see Fig. 3) of the airbag cover 1. A given by times ti and t ₂ deformation period 17, during which Force 15 acts at least on the area 4 'of the haptic layer 5 located in the weft channel 11, is 5 ms here. Within the deformation period 17, the absolute value F of the force 15 assumes a value F _A of approximately 10 kN and transmits at least to the region 4 'of the haptic layer 5 an amount of energy of 5 kj. It should be emphasized that the time course 18 of the absolute value F of the force 15 in FIG. 5a is shown only schematically. In fact, the time course of the force 15 may differ more or less from that shown here. In Fig. 5b is a time course 19 of the modulus of elasticity E of

Haptikschicht 5 in the area located in the firing channel 11 area 4 'of

Haptic layer 5 shown. It can be clearly seen that the elastic modulus E due to the force caused by the 15 deformation of the

Haptikschicht 5 increases within the deformation period 17 from an initial value Ei up to a final value E ₂ . In the present case, the initial value Ei is approximately 0.06 GPa (= 0.06 kN / mm ² ), which corresponds approximately to the value of the elastic modulus of polyurethane foam. Before the deformation, the haptic layer 5 thus has a soft feel desired for interior trim parts of vehicles. The final value E ₂ here is 5 GPa or 5 N / mm ² and thus corresponds approximately to the elastic modulus of wood perpendicular to the wood fiber. The elastic modulus E thus decreases in the region 4 'of FIG

Haptic layer 5 within the deformation period 17 at least partially in about a factor of one hundred to. The haptic layer 5 thus hardens at least partially abruptly. As a result, the majority of the amount of energy transferred from the airbag 8 to the haptic layer 5 or the force exerted by the airbag 8 on the haptic layer 5 - 15. B. at least 90 percent or at least 95 percent of the said amount of energy or the force 15 - on the hardened haptic layer 5 directly to the

Transfer decorative layer 2 so that it ruptures at least partially. This opens the airbag flap and releases the firing channel 11.

Finally, FIG. 6 shows the airbag cover 1 shown in FIG. 3 with deployed airbag 8. The airbag 8 has broken through the carrier 6, the haptic layer 5 and the decorative layer 2 along the tear lines defined by the perforations 12 (see FIG. 3) and deployed, driven by the gas generator 10, into the vehicle interior until a maximum volume is reached.

Only features disclosed in the embodiments of the various embodiments can be combined and claimed individually.

Claims

claims

1. Airbag cover (X), comprising a decorative layer (2) which closes the airbag cover (1) toward a vehicle interior, and a haptic layer (5) which is arranged on a side of the decorative layer (2) facing away from the vehicle interior,

characterized,

the haptic layer (5) is formed completely or at least partially from a dilatant material.

2. Airbag cover (1) according to claim 1, characterized in that at least a portion of the haptic layer (5) forming part of a

Airbag flap of the airbag cover (1) forms, wholly or at least partially formed from the dilatant material, wherein the airbag cover is set to be opened or pierced at least partially by the airbag (8) upon release of an airbag (8) and thus a firing channel ( 11) for the airbag (8) release.

3. Airbag cover (1) according to any one of the preceding claims, characterized in that the haptic layer (5) is at least partially formed as a film which is wholly or at least partially formed from the dilatant material, or that the haptic layer (5) at least partially as Composite is formed with a foamed polymer layer, wherein the dilatant material is integrated into the foamed polymer layer.

4. Airbag cover (1) according to any one of the preceding claims, characterized in that the decorative layer (2) and the haptic layer (5) are joined directly to one another.

5. Airbag cover (1) according to any one of the preceding claims, characterized in that the haptic layer (5) is weakened mechanically at least beretchweise.

6. Airbag cover (1) according to one of the preceding claims, characterized in that a thickness (14) of the haptic layer (5) is smaller than 10 mm, preferably smaller than 5 mm, particularly preferably smaller than 3 mm.

7. Airbag cover (1) according to one of the preceding claims, characterized by a carrier layer, wherein the haptic layer (5) between the carrier layer and the decorative layer (2) is arranged.

8. Airbag cover (1) according to claim 7, characterized in that the carrier layer is at least partially weakened mechanically.

9. Airbag cover (1) according to one of the preceding claims, characterized in that the decorative layer (2) comprises leather, a PVC skin or a TPO skin.

10. An airbag device comprising an airbag (8), a gas generator (10) and an airbag cover (1) according to one of claims 2 to 9, wherein the gas generator (10) and the airbag (8) in a non-triggered state of the airbag ( 8) are arranged on a side facing away from the vehicle interior side of the airbag cover (1) and wherein the gas generator (10) is adapted to inflate the airbag (8), so that the inflated airbag (8) pierces the airbag cover (1) and in the Vehicle interior unfolds.