Interior trim for a motor vehicle integrating a lid for an airbag

An embodiment of an interior trim for a motor vehicle integrating a lid for an airbag; the trim having: an inner layer, made of rigid plastic material having a behavior of a thermosetting type, which constitutes the skeleton; an intermediate layer, made of spongy plastic material that bestows softness to the touch; an outer coating layer having aesthetic purposes; and a reinforcement element, which is fixed with respect to the inner layer and involves the entire area of the lid.

PRIORITY CLAIM

The present application is a United States national phase application filed pursuant to 35 USC §371 of International Patent Application Serial No. PCTIB2007/003049, filed Oct. 12, 2007; which application claims priority to Italian Patent Application Serial No. BO2006A000711, filed Oct. 13, 2006; which foregoing applications are incorporated herein by reference in their entireties.

TECHNICAL FIELD

An embodiment of the present invention relates to an interior trim for a motor vehicle integrating a lid for an airbag.

BACKGROUND

In modern motor cars, there is an increasingly widespread presence of active and passive safety devices. In particular, inserted within the passenger compartment of a motor car is an increasing number of airbags in an attempt to protect all the occupants of the motor car in the best possible way in the event of an accident.

There is by now present in almost all new motor cars a front airbag for the passenger, said airbag being set in a housing within the dashboard that is closed at the front by a lid. In currently produced cars, there exist two types of lid for the airbag: either in view, i.e., visible on the aesthetic part of the trim, or else hidden from view, i.e., integrated in the skeleton and not visible on the aesthetic part of the trim.

In motor cars with the lid integrated in the skeleton, the coating material of the trim can be made of fabric, leather, or plastic material. To enable opening of the lid of the airbag in the event of an accident, at a point corresponding to the lid itself, the coating layer is pre-weakened by means of an internal line of incision (and hence not visible from the passenger compartment) that runs along the perimeter of the lid.

In known applications, the trim supporting the lid of the airbag has an inner layer made of moulded plastic material of a thermoplastic type (for example, polypropylene) that constitutes the skeleton, an intermediate layer made of spongy plastic material that bestows softness to the touch, and an outer coating layer having aesthetic purposes (for example, made of fabric or leather). However, providing the inner layer made of moulded plastic material of a thermoplastic type involves the construction of a relatively complex and costly production plant that calls for a yearly output of at least a few hundreds of thousands of pieces in order to be economically advantageous. Consequently, the use of moulded plastic material of a thermoplastic type may not be economically sustainable for a limited yearly output (for example, fewer than 4000-5000 pieces per year).

For a limited yearly production, it is economically advantageous to make the inner layer of the trim supporting the lid of the airbag made of thermosetting plastic material; however, thermosetting plastic materials are generally less elastic and more brittle than thermoplastic plastic materials. Consequently, using a thermosetting plastic material for making the inner layer of the trim supporting the lid of the airbag may give rise to the risk, at the moment of inflation of the airbag, of the lid bursting into pieces, with the slivers projecting (at least partially) in the direction of the passenger and thus constituting a serious hazard.

Furthermore, U.S. Pat. No. 6,092,835A1, which is incorporated by reference, discloses an automotive instrument panel having a concealed airbag. A molded substrate having first and second surfaces and an aperture there through receives an airbag; a curved metal door is secured to the second surface of the substrate by a plurality of fasteners extending through the substrate. The metal door has a generally U-shaped slot with first and second ends being spaced apart a distance greater than the length of the aperture. A molded covering overlies the second surface and the door and is secured thereto with an intermediate layer of foam and a foam gasket overlies the slot between the door and the substrate; a foam impermeable layer is placed between the gasket and door to prevent injected foam from impregnating the foam gasket and interfering with the opening of the door.

SUMMARY

An embodiment of the present invention is an interior trim for a motor vehicle integrating a lid for an airbag, the interior trim of which is free from the drawbacks described above, is in compliance with the specific norms and standards approved and certified at a world level, and at the same time is easy and economically advantageous to produce.

DETAILED DESCRIPTION

InFIG. 1, the reference number1designates as a whole a dashboard of a motor car with a view corresponding to the passenger side.

According to what is illustrated inFIGS. 1 and 2, the dashboard/is provided with an airbag2(illustrated inFIG. 2), which is set within a housing3(illustrated inFIG. 2), closed at the top by a lid4that is shaped so as to open in the event of inflation of the airbag2and under the thrust of the airbag2itself.

According to what is illustrated inFIG. 2, the lid4is integrated in a rigid interior trim5, which forms part of the dashboard1. The trim5comprises an inner layer6made of rigid plastic material having a behavior of a thermosetting type (typically a product of reaction, such as polyurethane or the like) that constitutes the skeleton, an intermediate layer7made of spongy plastic material that bestows softness to the touch, and an outer coating layer8(made of leather, fabric, or else plastic material) having an aesthetic purpose, as well as a purpose that is functional for the inflation and splaying-out of the airbag2. By way of example, the inner layer6has a thickness of 3-4 mm, the intermediate layer7has an undeformed thickness of 3 mm, and the outer layer8has a thickness of 1.5 mm.

Applied to the inner layer6is a reinforcement element9, which is fixed with respect to the inner layer6and involves the entire area of the lid4. According to the embodiments illustrated inFIGS. 2,3and5, the reinforcement element9comprises a metal plate10, which rests on a bottom surface11of the inner layer6, is connected rigidly to the inner layer6by means of mechanical fixing (for example, riveting) or gluing, and has at least one hinge12at an edge of the lid4of the airbag2.

According to what is illustrated inFIG. 2, at the edges of the lid4of the airbag2the trim5has a weakening incision13, which traverses the entire inner layer6, traverses the entire intermediate layer7, and only partially traverses the outer layer8. It should be emphasized that at a point corresponding to the hinge12the weakening incision13could traverse only the rigid inner layer6in so far as the layers7and8are flexible and hence behave locally like hinges additional to the hinge12of the metal plate10.

According to the embodiment illustrated inFIGS. 2 and 5, the metal plate10has a single hinge12set at an edge of the lid4of the airbag2. According to a different embodiment (not illustrated), the metal plate10has two hinges12, set in points corresponding to opposite edges of the lid4of the airbag2; in this case, the lid4also has a central weakening and is split into two halves to enable the airbag2to come out.

In use, during inflation and splaying-out of the airbag2, the pressure exerted by the airbag2as it expands on the lid4determines tearing of the outer layer8along the weakening incision13, and hence the subsequent opening of the lid4by means of a rotation of approximately 180° of the metal plate10about the hinge12.

To produce the trim5illustrated inFIG. 2, a method of production envisages making the inner layer6by means of injection moulding, of applying the intermediate layer7on the inner layer6formed previously by means of injection co-moulding or else by means of gluing, and of applying the outer layer8by covering the intermediate layer7with the leather.

Furthermore, the metal plate10may be applied by means of mechanical fixing (for example, riveting) or gluing to the inner layer6, and finally the weakening incision13may be made by laser cutting (or by means of a cut made using blades). To enable formation of the weakening incision13after application of the metal plate10, the metal plate10itself may have through slots set along the edge of the lid4of the airbag2to enable the action of the cutting means. Alternatively, the metal plate10could be applied to the inner layer6after the formation of the weakening incision13.

According to the embodiment illustrated inFIG. 4, the reinforcement element9, instead of the metal plate10, comprises a woven meshwork14, which is embedded in the inner layer6and is made of a fabric of polymer fibers (for example, polyester or polyethylene); the meshwork14may be embedded in the inner layer6by means of co-moulding, i.e., inserting the meshwork14in the mould of the inner layer6and then injecting the plastic material around the meshwork14.

According to the embodiment illustrated inFIG. 3, the weakening incision13traverses the entire inner layer6, only partially traverses the outer layer8, and does not traverse the intermediate layer7at all. The intermediate layer7may be made of foamed plastic material, which has a reduced strength and is easily torn by the force generated by the inflation of the airbag2even in the absence of weakening by an incision.

To produce the trim5illustrated inFIG. 3, a method of production envisages making the inner layer6by means of injection moulding and already provided with the respective weakening incision13(pre-shearing in the mould). Subsequently, the metal plate10is applied to the inner layer6by mechanical fixing (for example, riveting) or gluing, and then the intermediate layer7is applied to the inner layer6formed previously by means of injection co-moulding (or else by means of gluing). Finally, the weakening incision13is made on the outer layer8, and the outer layer8itself is applied, covering the intermediate layer7with the leather. Alternatively, after application of the intermediate layer7to the inner layer6, the intermediate layer7could be cut to make the weakening incision13also in the intermediate layer7itself.

According to an embodiment illustrated inFIG. 5, the inner layer6has a through hole15at a point corresponding to the lid4of the airbag2(i.e., the inner layer6is absent in an area corresponding to the lid4of the airbag2). The reinforcement element9comprises a metal plate10, which rests both on a bottom surface11of the inner layer6and on a bottom surface16of the intermediate layer7, is connected rigidly to the inner layer6, and has at least one hinge12at an edge of the lid4of the airbag2.

The metal plate10may be S-shaped in such a way as to present a first end17located at a point corresponding to the hinge12that rests on and is connected to the inner layer6, and a second end18opposite to the first end17and set between the inner layer6and the intermediate layer7.

To produce the trim5illustrated inFIG. 3, a method of production envisages making the inner layer6by means of injection moulding and already provided with the through hole15(i.e., pre-perforation in the mould). Subsequently, the metal plate10is applied to the inner layer6by means of mechanical fixing (for example, riveting or gluing), and then the intermediate layer7is applied to the inner layer6formed previously by means of injection co-moulding or gluing. Finally, the weakening incision13is made on the outer layer8, and the outer layer8itself is applied, covering the intermediate layer7with the leather. Alternatively, after application of the intermediate layer7to the inner layer6, the intermediate layer7could be cut to provide the weakening incision13also in the intermediate layer7itself.

In the embodiments described above, the trim5forms part of the dashboard1of a motor car. It should be noted that a further trim, altogether similar to the trim5described above, could be used for covering airbags set in parts of the motor car other than the dashboard (for example, door trim, belt trim, and trim for the underside and bottom parts of the dashboard).

One or more embodiments of the trim5described above presents numerous advantages in so far as it is easy and economically advantageous to produce even when it is produced with a limited yearly output. The low production cost of the trim5derives from the fact that plastic materials having a behavior of a thermosetting type may be used for making the inner layer6instead of thermoplastic plastic materials that involve the construction of a complex and costly production plant.

Furthermore, thanks to the presence of the reinforcement element9, even when it is subjected to the impulsive mechanical stresses produced by inflation and splaying-out of the airbag2, the inner layer6is not dangerous for the occupants of the motor car.

Naturally, in order to satisfy local and specific requirements, a person skilled in the art may apply to the solution described above many modifications and alterations. Particularly, although the present invention has been described with a certain degree of particularity with reference to one or more embodiments thereof, it should be understood that various omissions, substitutions and changes in the form and details as well as other embodiments are possible. Moreover, it is expressly intended that specific elements and/or method steps described in connection with any disclosed embodiment of the invention may be incorporated in any other embodiment as a general matter of design choice.