Structural unit for a gas bag module and gas bag module

Details Structural unit for a gas bag module and gas bag module Structural unit for a gas bag module and gas bag module

2000-06-16

2001-11-06

Swann, J. J. (Department: 3611)

Land vehicles

Wheeled

Attachment

C280S728200

Reexamination Certificate

active

06312007

ABSTRACT:

TECHNICAL FIELD
The invention relates to a structural unit for a gas bag module, in particular for a steering wheel gas bag module. The invention furthermore relates to a gas bag module.
BACKGROUND OF THE INVENTION
The covering cap of a steering wheel gas bag module is usually of plastic and is visible on the front face in the installed state of the module. The gas generator and the gas bag are inserted on the rear face into the container-shaped covering cap. A so-called gas generator carrier of sheet metal is fastened to the covering cap by means of rivets or hooks and forms the rear face of the covering cap which is to be closed after the insertion of the gas bag and the gas generator. The gas generator is fastened to this gas generator carrier and the entire module is attached to the steering wheel via this carrier. It is therefore obvious that the gas generator carrier must be constructed so as to be very stable and the connection between gas generator carrier and covering cap must withstand high tensile forces. On opening of the covering cap by the unfolding gas bag, in fact high forces are exerted onto the covering cap and hence onto the connection between covering cap and gas generator carrier.
The connections hitherto of gas generator carrier and covering cap, namely rivets and hooks, led to high pressures on the faces of the rivet- or hook apertures. The risk of the plastic covering cap tearing out was reduced by complicated undercuts to receive forces in the cap, which, however, were only able to be realized by costly injection tools. In addition, the rivets or hooks had to be placed as far away from the gas bag as possible and hence close to the rear face of the covering cap, so that a contact with the gas bag and a tearing of the gas bag by the rivets is avoided. This means, however, that the rivets had to be arranged very close to the rear edge of the covering cap, possibly even additional structural space was required in order to prevent a tearing out of the covering cap. The connection of covering cap and gas generator carrier by means of rivets or the bending of hooks is, in addition, very costly.
BRIEF SUMMARY OF THE INVENTION
The invention provides a simple and stable structural unit for a gas bag module, in particular a steering wheel gas bag module, which is distinguished in addition also by a small structural space and a connection, transferring high forces, between the gas generator carrier and the covering cap. This is achieved in a structural unit which comprises a gas bag, a gas generator carrier and a covering cap which consists of plastic material. The covering cap and the gas generator carrier limit an accommodation space for the gas bag. The gas generator carrier consists of a punched out and deformed sheet metal section having an edge side incorporated in a form-fitting manner into the covering cap. The sheet metal section is provided with tongues which are able to be bent inwards and towards each other so as to form the accommodation space and close it at a rear side. In the structural unit according to the invention, no additional parts such as rivets or hooks formed on the gas generator carrier are necessary. Rather, the gas generator carrier is itself incorporated into the covering cap, i.e. it is embedded into it in a form-fitting manner. An optimum embedding of the sheet metal section into the covering cap can be achieved in that the sheet metal section has recesses or projections which are penetrated by the covering cap. The inwardly bent tongues define a stable mounting base together with other parts of the gas bag module, e.g. with the gas generator and the holding plate for the gas bag.
Preferably, during the production of the covering cap by casting technique or by injection molding technique, the sheet metal section is incorporated into it in a form-fitting manner. The liquid plastic can then also actually fill all the recesses in the gas generator carrier.
The tongues are able to be folded over approximately at right-angles around bending lines, along which in the sheet metal section a weakened zone of material, e.g. a perforation, is formed.
The stability of the entire housing can be increased in that the sheet metal section has a marginal zone which is deformed by folding or the like into a surrounding rim. In this surrounding rim, the sheet metal section can be embedded into the covering cap. This marginal zone also preferably has the recesses for the form-fitting engagement of the plastic material.
According to the preferred embodiment, the sheet metal section has several tongues which are able to be bent over, which are arranged on the surrounding rim preferably in pairs lying opposite each other.
The rear face of the housing of the gas bag module formed by the covering cap and the gas generator carrier is then closed by the bending over of the tongues, after the gas bag with gas bag holding plate and possibly also the gas generator (depending on the system which is aimed for) have been inserted into the covering cap.
A space-saving possibility for fastening the structural unit according to the invention to the vehicle is achieved in that the tongues have at least one outwardly projecting mounting flange each. In addition, the tongues can carry fastening means, by means of which the gas bag module is arrested on the vehicle. As fastening means here, for example, so-called snap-in bolts, press-in nuts or the like are possible, which are attached to the tongues. Also other fastening means are able to be integrated very simply into the tongues.
At their free edge, the tongues have in addition a plastic border which facilitates a gripping of this free edge. The free edge having the plastic border can, furthermore, serve to establish the horn contact, the exact positioning of the gas generator in axial direction, so that it projects from the module in a defined manner, or the guidance of the gas bag module. The plastic border permits a complicated shaping.
After the folding over of the tongues through approximately 90°, these form sections of a base region which has a recess for the arrangement of the gas generator and also openings for connecting screws. The gas generator can project through this recess outwards from the housing of the gas bag module. The openings for the connecting screws permit the arresting of the gas generator and of a gas bag holding plate on the gas generator carrier. Thereby, all the individual parts are connected to a gas bag module, in which the rim of the inflation opening of the gas bag is clamped between the gas bag holding plate and the free edge of the tongues.
The invention further relates to a gas bag module, comprising a structural unit according to the invention, in which the tongues, after folding over through approximately 90°, form one section each of a base region, which has a recess for the arrangement of the gas generator and also openings for connecting screws. By means of the connecting screws, a gas bag holding plate as part of the gas bag module and a flange of the gas generator with the gas generator carrier are combined into the gas bag module. The rim of the inflation opening of the gas bag is clamped between the gas bag holding plate and the free rim of the tongues. The gas bag module according to the invention is distinguished by a simple and stable connection of gas bag holding plate with gas generator and gas generator carrier. Furthermore, the tongues are fastened to the covering cap in a stable manner. The gas generator is immediately, i.e. directly, attached to the tongues, i.e. no additional parts are arranged between the tongues and the gas generator. The gas generator, the tongues and the holding plate complete each other to define a stable base. Via the stable mounting base the module is attached to the vehicle.


REFERENCES:
patent: 5700029 (1997-12-01), Enders
patent: 5765865 (1998-06-01), Nagata et al.
patent: 5794968 (1998-08-01), Yamamoto et al.
patent: 5833262 (1998-11-01), Fujita et al.
patent: 5873596 (1999-02-01), Kantoh et al.
patent: 5904366 (1999-05-01), Nishijim

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