Airbag module

The invention relates to an airbag module for an occupant restraint system of a motor vehicle, comprising a housing in which a folded inflatable airbag is accommodated.

An airbag module of the initially named kind is known and is intended to protect the vehicle occupants from injuries in accidents. For this purpose, the airbag is inflated during the accident within a few milliseconds and forms a cushion into which the passenger immerses during the sudden deceleration of the vehicle.

An object of the invention is to provide an airbag module for an occupant restraint system of a motor vehicle which can be cost-effectively manufactured and which helps to prevent injuries to occupants.

For satisfying this object, an airbag module with the features in accordance with the claims is proposed, in particular an airbag module in which a part of the housing is designed as a covering which is movable into the vehicle interior and which serves during the unfolding of the airbag for supporting the knees of the occupant, and in which the airbag is designed in such a manner that it can be unfolded through an opening at the housing past the covering and into the vehicle interior when the covering is at least partly moved into the vehicle interior. In one embodiment, the moveable covering is a flap which is pivotal about an angle of less than 45 degrees. In one embodiment, the movable covering is a flap which is pivotal about an angle of less than 45°.

In the invention, both the housing and the airbag fulfill a double function. On the one hand, the housing serves for the accommodation of the airbag. On the other hand, the covering of the housing, which is moved into the vehicle interior during an accident supports the knees of the occupant so that the latter is retained in his seat during an accident. The airbag which is unfolded and inflated past the covering and into the vehicle interior in turn supports the covering and presses the latter against the knees of the occupant. At the same time, the airbag prevents injuries to the upper torso and to the head of the occupant, who continues moving forward in the direction of travel during the sudden deceleration of the vehicle. Furthermore, by the use of said housing with said covering the construction of the airbag module is comparatively simple so that the manufacture of the airbag module in accordance with the invention is simpler in comparison with known airbag modules.

Thus, it is particularly advantageous when the covering is stiffened through additional stiffener elements. By this, the supporting forces which are exerted by the knees of the occupant on the covering during the accident are transmitted by the stiffened covering over a large area of the airbag, so that the pressure in the airbag acting to support the covering can be lower than if the corresponding supporting forces had to be taken up by the airbag in a point-like manner.

In a preferred further development of the invention a flap being pivotal into the vehicle interior is used as movable covering. The use of a flap as covering has on the one hand the advantage that the flap assumes a definite position relative to the housing during the unfolding of the airbag, whereby the unfolding of the airbag can be intentionally influenced when the flap is designed accordingly. On the other hand the forces which are exerted during the accident by the occupant on the flap are partially transmitted to the housing by the pivot points of the flap so that the airbag only needs to take up and to intercept a portion of the forces arising at the flap.

Furthermore, it is advantageous when the airbag is firmly connected to the inner side of the housing which faces the covering. By this, it is achieved that the airbag is supported via the housing at the body of the vehicle. Alternatively, it is possible to provide the airbag at an inner side of the covering.

In a further preferred embodiment of the invention the housing of the airbag module forms a pivotal lid of a glove compartment. In this way the airbag can be arranged space savingly in the vehicle interior. At the same time an additional lid for the glove compartment can be ceased.

The invention will be described in more detail in the following with reference to the embodiments and with reference to the drawings, wherein:

FIG. 1 shows a perspective view of a first embodiment of an airbag module which is provided in the vehicle interior of a motor vehicle on the front passenger's side;

FIG. 2 shows a side view of the airbag module in accordance with FIG. 1 in an undeployed condition;

FIG. 3 shows a side view of the airbag module in accordance with FIG. 1 during the unfolding of the airbag; and

FIG. 4 shows a side view of a second embodiment of an airbag module, the housing of which forms a pivotal lid of a glove compartment.

FIG. 1 shows a perspective view of the front passenger's side in the vehicle interior of a motor vehicle 10 . The vehicle interior is lined with a large number of liner elements 12 . The lining in the front region of the vehicle interior forms a dashboard 16 which borders directly at a windshield 14 of the motor vehicle 10 . At the upper side of the dashboard 16 a shelf 18 is molded at the front passenger's side. A first embodiment of an airbag module 20 is arranged below the shelf 18 . The airbag module 20 has a housing 22 with a rear wall 26 which is secured at a body component 24 of the motor vehicle 10 . The rear wall 26 is firmly connected to the body component 24 for example with screws or rivets.

At the lower side 28 of the housing 22 , which extends transversely to the longitudinal direction of the vehicle, a gas generator 30 for an airbag 32 is provided, said airbag being in FIGS. 1 and 2 illustrated in a folded manner. Furthermore, a rectangular flap 34 is pivotally journalled at the lower side 28 of the housing 22 and is held for example by holder lugs in a position in which the flap 34 extends parallel to the rear wall 26 and spaced apart from the latter. In the illustrated embodiment the sides and the upper side of the housing 22 are open so that only the rear wall 26 , the lower side 28 and the flap 34 form an accommodation for the airbag 32 . The airbag 32 is folded in a known manner to form an airbag packet which is inserted into the housing 22 and is connected to the gas generator 30 .

The airbag module 20 is arranged behind a lining flap 36 which is pivotally journalled below the dashboard 16 . By means of securing elements 38 the lining flap 36 is firmly connected at its rear side facing away from the vehicle interior to the outer side of the flap 34 facing away from the interior of the housing 22 . The front side of the lining flap 36 , which faces into the vehicle interior, is cushioned for example by a foam material.

In the following, the method of operation of the airbag module 20 will be explained in more detail with reference to FIGS. 2 and 3. As soon as the motor vehicle 10 becomes involved in a severe accident, the gas generator 30 is ignited by an ignition device (not illustrated). The gas generator 30 starts to inflate the airbag 32 , through which the airbag 32 begins to unfold, whereas the flap 34 of the housing 22 still remains in its initial position. By means of the increasing gas volume in the airbag 32 , said airbag 32 is further inflated, is braced at the inner side of the rear wall 26 , while pressing against the flap 34 . As soon as the force acting on the inner side of the flap 34 through the increasing volume of the airbag 32 is greater than the holding force with which the flap 34 is held closed, the flap 34 pivots in the direction of the vehicle interior. As a result, the cushioned lining flap 36 is opened at the same time and comes in contact with the knees of the front occupant 40 . As soon as the flap 34 and the lining flap 36 are opened, the airbag 32 emerges from an opening 42 which is formed below the dashboard 16 and unfolds to its maximum size between the dashboard 16 and the upper torso of the front passenger 40 .

Through the high pressure acting in the interior of the airbag 32 the flap 34 is pressed together with the lining flap 36 against the knees of the front passenger 40 so that the front passenger 40 is held in the front passenger's seat (not illustrated). At the same time, the completely inflated airbag 32 prevents the front passenger 40 from being injured at his upper torso or at his head.

Since the forces acting on the lining flap 36 and thus on the flap 34 in particular through the knees of the front passenger 40 are relatively significant, the flap 34 is stiffened in addition so that the forces arising are uniformly distributed over the entire width of the airbag 32 .

FIG. 4 shows a second embodiment of an airbag module 50 . In this embodiment the air bag module 50 also serves at the same time as a lid for a glove compartment 56 being arranged under a dashboard 52 of a vehicle 54 and being secured at a body component 58 of the vehicle 54 . The airbag module 50 has a housing 60 formed of a rear wall 62 , a front wall 63 , and a flap 64 . Housing 60 is pivotally journalled at a rear wall 62 to body component 58 . At the under side of the housing 60 , which extends transversly to the longitudinal direction of the vehicle 54 , a gas generator 66 is secured, to which a folded airbag 68 being accommodated in the housing 60 is connected. At the sides and its upper side the housing 60 is closed for example by a thin plastic layer 61 in order on the one hand to protect the airbag 68 which is accommodated in the housing 60 and on the other hand to hold the flap 64 in a definite position with respect to the rear wall 62 .

The housing 60 is pivotally journalled at its lower side at the body component 58 and at the same time serves as a lid for the glove compartment 56 . For this purpose the housing 60 of the airbag module 50 can be pivoted back and forth between an open position (illustrated in broken lines) in which the glove compartment 56 is open and a closed position in which the glove compartment 56 is closed. Furthermore, a catch 70 is provided at the housing 60 by means of which the rear wall 62 of the housing 60 is locked at the body component 58 when the housing 60 is closing the glove compartment 56 .

The method of operation of the airbag module 50 corresponds substantially to the method of operation of the above described first embodiment. In order to ensure a correct unfolding of the airbag 68 the housing 60 , which is designed as the lid for the glove compartment 56 , must however be pivoted into its closed position, in which it is locked at the body component 58 . If the motor vehicle 54 is involved in certain accident conditions, the gas generator 66 is ignited and inflates the airbag 68 . Through the unfolding airbag 68 the flap 64 of the housing 60 is opened and presses against the knees of a front passenger 72 , who is held in his seat in this manner. As soon as the flap 64 has opened the housing 60 , the unfolding airbag 68 emerges from the opened housing 60 and unfolds to its maximum size between the dashboard 52 and the upper torso of the front passenger 72 . In this case as well the airbag 68 prevents injuries to the upper torso and the head of the front passenger 72 , whereas at the same time the flap 64 , which is pivoted into the vehicle interior by the airbag 68 , holds the front passenger 72 in his seat.

In the above explained embodiments a housing was in each case described which is formed of a rear wall and a flap which is pivotally journalled at the latter. Alternatively, it is also possible to use a movable covering instead of a flap which is for example held at the rear wall by holder lugs and is moved by the airbag of the airbag module into the vehicle interior during an accident. It will also be understood that although the invention is described on a passenger side, that it may also be used on in other vehicle locations, such as the driver's side.