Abstract:
The disclosed apparatus can control the cross section of at least one vent opening of an airbag module, through which gases can escape into the environment. The apparatus can include: at least one covering part for at least partially covering the at least one vent opening and an operating mechanism comprising a gas source and an inflatable element in fluid communication with the gas source. The inflatable element can be configured to produce a variation in the outlet cross section of the vent opening in cooperation with the covering part.

Description:
BACKGROUND 
   The application relates to an apparatus for controlling the outlet cross-section of a vent opening for an airbag module. 
   An airbag module typically includes a gas bag and a gas generator for inflating the gas bag in case of a collision, so that the inflated gas bag forms a gas cushion for protecting an occupant of the vehicle. The gas cushion acts as a restraining device which dampens the impact on an occupant, and especially prevents a direct impact of the occupant against certain injurious parts of the vehicle. 
   The optimum internal pressure of the gas bag in the inflated state, so as to protect an occupant against injury, is dependent upon a number of parameters, for example the size and weight of the occupant to be protected, the position of the occupant at the moment of a collision, and the nature and gravity of the accident. It is therefore expedient to provide on the airbag module, such as on the gas bag or another component of the airbag module (for example, at a connection between the gas generator and the gas bag), including exhaust or vent openings through which gas can flow out from the airbag module, especially from the inflated or yet-to-be-inflated gas bag. Furthermore, the at least one vent opening, through which gas (produced by the gas generator of the airbag module and originating from the airbag module) can flow away into the environment, can also be arranged outside of the airbag module, especially on a vehicle part containing the airbag module, for example a back-rest of a vehicle chair in the case of a side-airbag module. 
   The amount of gas released from the gas generator for the inflation of the gas bag is so chosen that it permits the production of the maximum internal pressure in the gas bag, which at certain values of the above-stated parameters proves optimum for the protection of an occupant. In the presence of other values of the above-stated parameters, exhaust or vent openings provided on the airbag module can then serve for reducing the internal pressure in the gas bag, advantageously at certain points in time during and/or after the inflation of the gas bag. For this purpose, it is known to vary the exhaust cross section of a particular vent by varying the position of a covering part with which the vent can be covered, by means of an associated actuating mechanism, such that the vent opening will have a cross section adapted to the values of the above-stated parameters. 
   The present invention is addressed to the problem of improving an actuating mechanism by which the exhaust cross section of a vent opening will be adjustable, especially in regard to the possibility of a flexible integration of the actuating mechanism into an airbag. 
   SUMMARY 
   This problem can be solved according to an embodiment of the present invention by the creation of an apparatus for controlling the cross section of at least one vent opening of an airbag module with an operating mechanism comprising a gas source and an element inflatable by means of the gas source. When the element is inflating, it cooperates with the covering part covering the vent opening such that it produces a variation in the outlet cross section of the vent opening. 
   Accordingly, a fastening mechanism is provided through which the outlet cross section of the vent opening is controllable. A gas source and an element inflatable by means of the gas source, which in the case of inflation cooperates with a covering element associated with the particular vent opening, brings about a change in the outlet cross section of the vent opening. 
   The solution according to the present invention can have the advantage that an actuating mechanism, which may comprise an inflatable element and an associated gas source, can be flexibly positioned in an airbag module while the inflatable element can also be folded with the gas bag serving for the protection of the vehicle&#39;s occupants. Such an actuating mechanism using a small number of components permits a defined control of the outlet cross section of a vent opening, and thus permits a defined control of the internal pressure of the gas bag. 
   The gas source filling the inflatable element with gas can advantageously form a component which is separate from the at least one gas generator which serves to inflate the gas bag protecting the occupants. In particular, the gas source can be controlled separately (and independently) from the gas generator so that the time that the gas source is started for inflating the inflatable element is not established by the instant at which the gas generator is started for the inflation of the gas bag protecting the vehicle&#39;s occupant. Thus, the gas source can be ignited at moments in time which are not predetermined by the ignition of the gas generator. The gas source can therefore be activated, e.g., ignited, to fill the inflatable element with gas simultaneously with the gas generator or at a specific moment after the gas generator. Due to the possibility of igniting the gas source at any time before, during or after the activation of the gas generator provided for the inflation of the gas bag, the internal pressure of the gas bag can be optimally controlled and adapted to a particular accident situation and to the size and position of the occupants to be protected so that optimum adaptability is provided. 
   Moreover, the gas source associated with the inflatable element can be preferably separated spatially from the gas generator serving to inflate the gas bag. Thus, a flexible arrangement of the actuating mechanism comprising the gas source and the inflatable element is made possible. 
   The gas source associated with the inflatable element may be preferably designed for the pyrotechnical generation of gas. The inflatable element has clearly less bulk, compared with the inflatable gas bag in the gas-filled state, because it serves only for the control of at least one vent opening of the airbag module. Thus, the amount of gas necessary for the filling of the inflatable element can be generated simply by an igniter, for example, one in the form of an ignition battery which usually serves to ignite the pyrotechnical charge of a gas generator of an airbag module without the need for an additional pyrotechnical charge. 
   The gas source may be preferably disposed in the space surrounded by the covering of the inflatable element. However, the gas source can also be basically disposed outside of the inflatable element and be connected with the inflatable element by a gas-conducting connector. 
   The inflatable element, which has an envelope of a flexible material (for example a fabric), is an element separate from the gas bag to be inflated. That is, the envelope of the inflatable element is not a component of the envelope of the gas bag but it can be connected therewith, in order to, for example, cover the vent opening provided on each gas bag. The gas bag in the inflated state envelops a definite first volume while the inflatable element in the gas-filled state envelops a second volume different from the first volume and may preferably lie outside the first volume. Alternatively, the second volume can lie within the first volume. 
   Upon the filling with gas, the influence of the inflatable element on the associated covering part to change the outlet cross section of at least one vent opening takes place by utilizing the change of volume of the inflatable element upon the filling with gas, especially the accompanying change in the spatial position of the envelope of the inflatable element as well as a stiffening of that envelope. 
   According to a preferred embodiment of the present invention, the inflatable element can be a tube-like shape so that its size in at least one direction, for example the longitudinal direction, of the tube increases when filling with gas. 
   According to an embodiment of the present invention, the covering part provided for covering over at least one vent opening can be a component of the inflatable element, especially an integral component of the envelope of the inflatable element. In another embodiment of the present invention, the covering part can be a part separate from the envelope of the inflatable element. That is, the covering part is a part which—in contrast to the envelope —does not serve to define the interior of the inflatable element but which can be joined to the envelope of the inflatable element. 
   The apparatus according to one embodiment of the present invention can, on the one hand, be arranged and configured such that the covering part closes first partially or completely the at least one associated vent opening, i.e., before the inflatable element fills with gas, and such that, when the inflatable element is filled with gas, such an effect is made on the covering part that the outlet cross section of the vent opening is enlarged, i.e., the covering part releases the vent opening. On the other hand, the vent opening can be provided such that it is uncovered at least partially at first, i.e., before the inflatable element fills with gas, and is covered increasingly by the filling of the inflatable element with gas so that the outlet cross section also diminishes. 
   According to another embodiment of the present invention, before the inflatable element is filled with gas, the covering part is releasably fastened in a position in which it covers partially or completely one vent opening. This connection is releasable, preferably destroyable, by forces which are produced upon the filling of the inflatable element with gas and the accompanying enlargement of the volume of the releasable element. The connection serving to fix the covering part in a certain position can especially be in the form of a tear-open joint, for example in the form of a tear seam. 
   The vent opening to be covered can be provided in the envelope of the inflatable gas bag, and the covering part can be joined to the envelope such that it covers the vent opening. The connection between the gas bag and the covering part (which can be formed by a portion of the envelope of the inflatable element) can simultaneously join two areas of the envelope of the inflatable element. The two areas can move apart from one another when the inflatable element fills with gas so that the connection is released, preferably destroyed. 
   According to another embodiment of the present invention, the inflatable element can reach through a vent opening such that the vent opening is not completely closed before the inflatable element fills with gas, i.e., the escape of gas through the vent opening is possible. The inflatable element can be configured and arranged in regard to the vent opening such that it completely closes the vent opening in the gas-filled condition. In the case of a vent opening of circular shape, for example, the inflatable element is so configured that it has a substantially circular cross section in the gas-filled state, for example the inflatable element can have a hollow cylindrical shape. 
   The envelope of the inflatable element can be configured, on the one hand, such that no gas can escape from the inflatable element. In this case, after the inflatable element is filled with gas, the associated vent opening is permanently closed. On the other hand, the envelope of the inflatable element can have a defined permeability to gas, for example in that that envelope has a vent opening so that the inflatable element, after filling with gas, reduces its volume again and thereby again releases the associated vent opening, at least partially. 
   According to another embodiment of the present invention, the covering part can be formed by a flexible portion which lies on the inflatable element (and in this case can be connected with it sectionally) and simultaneously covers, at least partially, a vent opening. By filling the inflatable element with gas and accompanied by the change in the volume of the inflatable element, the covering part is lifted; thus releasing the associated vent opening. 
   According to one embodiment of the present invention, an airbag module for controlling the cross section of at least one vent opening of the airbag module can be characterized by having a gas bag, a gas generator, a vent opening, and an apparatus for controlling the cross section of the vent opening. 
   It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further details and advantages of the invention will be made clear in the following description of its embodiments, with the aid of the drawings. 
       FIG. 1  shows a first embodiment of a vent opening of an airbag module, which is covered by a covering part, in which the covering part is removable by means of an actuating mechanism for the release of the vent opening. 
       FIGS. 2   a  and  2   b  show a top plan view and a cross section of a second embodiment of the present invention in which the vent opening is covered by an associated covering part. 
       FIGS. 3   a  and  3   b  shows a top plan view and a cross section of the embodiment of  FIGS. 2   a  and  2   b  after the removal of the covering part from the vent opening. 
       FIGS. 4   a  and  4   b  show an embodiment of the present invention in which an inflatable element can be used for closing the vent opening.  FIG. 4   a  shows the system before the inflatable element is filled with gas.  FIG. 4   b  shows the system after the inflatable element is filled with gas. 
       FIGS. 5   a  and  5   b  show another embodiment of the present invention.  FIG. 5   a  shows the system before the inflatable element is filled with gas.  FIG. 5   b  shows the system after the inflatable element is filled with gas. 
       FIG. 6  shows a schematic representation of an airbag module for a motor vehicle according to an embodiment of the present invention. 
       FIGS. 7A ,  7 B, and  7 C show various possibilities for arranging the covering part and the associated operating mechanism on a gas bag. 
   

   DETAILED DESCRIPTION 
   In  FIG. 6 , an airbag module for a motor vehicle is represented schematically in which the airbag module comprises an inflatable gas bag A and a gas generator G for filling the gas bag A. The gas bag A and the gas generator G are disposed in a modular housing M whose upper covering surface is closed by a cap K. 
   In the case of a collision, the airbag module is activated by the ignition of the gas generator G which then releases gas to inflate the gas bag A. When the gas bag A is inflated it unfolds and an opening is released in the cover K of the airbag module M by the pressure of the unfolding gas bag A, and through the opening, the gas bag A can unfold to protect a vehicle occupant. 
   On the airbag module, more precisely on the gas bag A, in order to reduce the internal pressure in the gas bag A, a vent opening O is provided through which gas can escape from the interior of gas bag A into the environment. The vent opening O is controllable in regard to the size of its outlet cross section. Because the vent opening O is controllable, both the moment at which gas can issue from the interior of the gas bag A into the environment and the amount of the escaping gas can be controlled. Thus, the internal pressure of the gas bag A can be controlled, according to the values of certain parameters which determine the optimum internal pressure of the gas bag A to protect a vehicle&#39;s occupant. These parameters can include, for example, the size, the weight and the position of the occupant who is to be protected within the vehicle as well as the nature and severity of the accident that leads to the ignition of the gas generator G. 
   Various embodiments of the present invention will now be explained with reference to  FIGS. 1 to 5   b , in which an apparatus with a vent opening O of the kind shown in  FIG. 6  can be affected with regard to its outlet cross section by releasing or closing the vent opening O at a certain moment in time. 
   In the embodiment represented in  FIG. 1 , two layers L 1  and L 2  lying opposite one another are shown which can involve an upper part and a lower part (or a front part and a rear part) of the gas bag A. The two layers L 1  and L 2 , as components of the envelope of the gas bag A, can define the interior IR of the gas bag A, which can be inflated by the delivery of gas. In the case of two envelope portions, the layers L 1  and L 2 , for example, can be two separate gas bag parts, especially in the form of fabric layers which are suitably joined together, e.g., by sewing and/or cementing. Alternatively, the two envelope parts L 1  and L 2  can also form two portions of a one-piece gas bag envelope which can consist, for example, of a single three-dimensional fabric layer. 
   The envelope of gas bag A, formed by the two gas bag layers L 1  and L 2  (or in other cases, other gas bag parts not shown in  FIG. 1 ), has a vent opening O (such as, in one of the gas bag layers L 1  and L 2 ) through which gas can escape from the interior IR of the gas bag A into the environment, whenever the gas bag shown in the uninflated state in  FIG. 1  is inflated by a gas generator G, as explained in  FIG. 6 . 
   In the uninflated state of gas bag A shown in  FIG. 1 , the vent opening O is at first covered by the covering part  3  which forms a component of the envelope  20  of an inflatable element  2  in the form of a filling tube. The envelope  20  of the filling tube  2  extends along a longitudinal direction E and can comprise two flexible envelope parts  21  and  22  which—as seen along the longitudinal direction E—accommodate a gas source  1  at one end  25  and at the opposite end  26  are joined together by a gas-tight seam. The envelope parts  21  and  22  can be, for example, formed as fabric pieces. The gas source  1  provided at the one end  25  may include a receiver  10  for a pyrotechnical charge and an igniter  12  in the form of an ignition battery for igniting the pyrotechnical charge on the basis of electrical impulses which can be fed to the igniter  12  in a known manner by means of connecting lines  14 . 
   Provided that the inflatable element  2  is made sufficiently compact with a correspondingly small bulk in the gas-filled state, then according to a preferable embodiment, the additional pyrotechnical charge can be avoided and the ignition of the igniter  12  in the form of an ignition battery can release gas that can be exclusively used for filling the inflatable element  2 . In other words, the gas released by the igniter  12  completely fills the inflatable element  2  with gas and is used in the gas generator G for the inflation of the gas bag A by igniting an additional pyrotechnical charge in the gas generator G for producing the necessary gas for the inflation of the gas bag. 
   The gas source  1 , especially its ignition mechanism, is connected by the connecting lines  14  to an electrical control apparatus S in which the values of certain given parameters, which are determined, e.g., by sensors, are brought together and evaluated. These determined parameters are important for the establishment of an optimum internal pressure in the gas bag A when the gas bag is inflated in a collision, particularly for the setting of an optimum internal pressure in the interior IR of the gas bag A at certain points in time. 
   The housing-like container  10  of the gas generator  1  is established at the one end  25  of the filling tube  2  between the two envelope parts  21  and  22  by means of a clamping ring  18  and a clip  16  disposed within the filling tube  2  such that the two envelope portions  21  and  22  are joined in a gas-tight fashion at the end  25 . 
   Thus, the two envelope parts  21  and  22  of the envelope  20  together with the gas source  1  arranged at one end of the filling tube  2  and the seam provided at the other end of the filling tube  2  surround an interior space of the inflatable element in the form of a filling tube in a gas-tight manner. 
   The filling tube  2  covers with its envelope  20 , more precisely with its one envelope part  21 , the vent opening O of the gas bag A. The envelope is joined to the envelope of the gas bag A along the periphery of the vent opening O by releasable junctions  27  and  28  in the form of at least one tear seam. Particularly, the envelope  20  is joined to the envelope of the gas bag A at the one gas bag layer L 2 . The releasable junctions  27  and  28  extend in the form of tear seams along the circumference of the vent opening O and they simultaneously join together the two ends of the opposing envelope parts  21  and  22  of the filler tube  2 . 
   If, in the event of a collision, the gas bag A is filled with gas by an associated gas generator G to protect an occupant of the vehicle, as represented for example in  FIG. 6 , this gas at first cannot pass out again from the interior IR of the gas bag through the vent opening O and therefore remains in the gas bag A (unless the gas bag A has other gas-permeable areas). 
   If, however, it is determined by a controller S associated with the gas source  1  that, to establish optimum protection of an occupant of the vehicle under the actual conditions and it is expedient to open the vent opening O in the envelope of the gas bag A, the igniter  12  of the gas source associated with the filler tube  2  is ignited by the controller S via the electrical connecting lines  14 . Thus, by the combustion of a pyrotechnical charge provided in the receiver  10  of the gas source  1 , a gas is produced which flows into the interior of the filler tube  2  so that the filler tube unfolds transversely along its length E. In this case, the two envelope parts  21  and  22  lying opposite one another tend to separate from one another along a direction Q perpendicular to the longitudinal direction of the tube. The releasable joining parts  27  and  28  (in the form of tear seams  27  and  28 ) become greatly stressed so that they pull apart while the junction between the envelope parts  21  and  22  of the filler tube  2  and the envelope of the gas bag A (or more precisely the one layer L 2  of the envelope of the gas bag A) is released. Thus, there is no longer a strong junction between the envelope  20  of the filler tube  2  and the envelope L 1  and L 2  of the gas bag A so that the vent opening O in the envelope L 1  and L 2  of the gas bag A is no longer closed by the envelope  20  of the filler tube  2 . Gas can then issue from the interior of the gas bag A through the vent opening O into the environment in order to reduce the internal pressure in gas bag A, and thus put the internal pressure at an optimum value for the protection of the occupants under the given conditions. 
   It is to be noted that in  FIG. 1  only a small section of the gas bag A and its envelope L 1 , L 2  is shown while the filler tube  2  forming an associated inflatable element serving to close the vent opening O is shown substantially in full. Accordingly, the envelope surface of the gas bag A is substantially larger than the envelope surface of the filler tube  2 . The gas bag A can comprise a substantially larger volume with its envelope L 1 , L 2  in the inflated state than the inflatable element  2  in the form of a filler tube with its envelope  20 . 
   In the embodiment represented in  FIG. 1 , the inflatable element  2  is arranged outside of the gas bag A so that, in the inflated state of the filler tube  2 , the volume enclosed within it is outside of the volume enclosed by the gas bag A. 
   Furthermore, it is to be noted that the inflatable element  2  does initially close the air outlet opening O of the gas bag A, and is fixedly bound section-wise to the envelope L 1 -L 2  of the gas bag A. However, the inflatable element  2  expressly forms no lasting component of the envelope L 1 -L 2  of the gas bag A because the filler tube  2 , when the gas bag A is inflated to protect a vehicle&#39;s occupant and at least if certain conditions are satisfied, is designed to separated from the envelope L 1 -L 2  of the gas bag A by means of an associated controller S and gas source  1  in order to free the vent opening O. 
   An embodiment of the present invention is shown in  FIGS. 2   a  and  2   b , wherein a first difference is the fact that the vent opening O which is to be closed by means of a covering element  3  is not provided in the gas bag but in a bottom part of a module housing M of the airbag module. Also, in this embodiment, there is not just a single vent opening O which is to be closed by a covering part  3  but two vent openings O are covered and closed simultaneously by means of a covering part  3 . The vent openings O in the module housing M can also serve for exhausting gas (produced by a gas generator) before any gas has passed into the gas bag A. 
   An additional difference between the embodiment of  FIGS. 2   a  and  2   b  and the embodiment of  FIG. 1  is the covering part  3  provided for closing the inflatable element  2 . According to  FIGS. 2   a  and  2   b , the covering part  3  does not serve to define and surround the interior space of the filler tube  2  which can be filled with gas. Instead, the covering part  3  is a flexible piece—for example in the form of a fabric layer  30 —separate from the filler tube  2 . 
   In this case, the covering part  3  can comprise a middle section  31  that lies flat on the envelope  20  of the inflatable element  2  and two lateral sections  32  standing apart from the middle section  31  of the covering part  3 . The vent openings O are arranged on either side of the filler tube  2  while the filler tube is in the uninflated state (i.e., the initial situation) in which the vent openings O are closed by the covering part. 
   The middle section  31  of the covering part can be joined in an appropriate manner to the envelope  20  of the inflatable element  2 , for example, by cementing or sewing. In a like manner, the free ends of the lateral sections  32  of the covering part can be releasably fixed to the modular housing M. Thus, the covering part  3  can be held specifically in the position shown in  FIGS. 2   a  and  2   b  in which the covering part covers the associated vent openings O and closes them to such an extent that little or no amounts of gas can pass through these vent openings O. 
   In the case of a collision, if the controller S (shown in  FIG. 1 ) determines that gas is to flow through the vent openings O in order to optimize the pressure conditions within the gas bag G (shown in  FIG. 6 ), the gas source  1  is ignited through the electrical connecting lines  14  by means of the controller S. As a result, gas is released from the gas source  1  and the inflatable element  2  is filled with the gas so that the inflatable element changes to the state shown in  FIGS. 3   a  and  3   b . In this case, the volume enveloped by the envelope  20  of the filler tube  2  increases while the two envelope parts  21  and  22  of the envelope  20  of the filler tube  2  separate from one another along a direction Q across the longitudinal direction E of the filler tube  2 . In this manner, the covering part  3  lying on the envelope, particularly on the portion  22  of the envelope  20 , is lifted away from the vent openings O so that gas can issue from the vent opening. 
     FIG. 4   a  shows an embodiment of an apparatus for controlling the cross section of a vent opening O in which the vent opening O is provided in the envelope of a gas bag A which can be inflated to protect a vehicle occupant. The covering part  3  that is provided for closing the vent opening O is integrated into the envelope  20  of the inflatable element  2 . The inflatable element  2  is in the form of a filler tube. 
   An important difference from the embodiment of  FIG. 4   a  with the previous embodiments is that, in  FIG. 4   a , the associated vent opening O is opened so that gas can issue through it out of the interior space IR of the gas bag A into the exterior space A when the inflatable element  2  is in the slack case, i.e., not the gas-filled state. 
   For this purpose, the inflatable element  2  is arranged such that it reaches through the vent opening O in the envelope of the gas bag A without closing it. A releasable connection  29  is provided in the form of a rip seam between two envelope portions  21  and  22  of the envelope  20 , and joins these two portions  21  and  22  together such that the filler tube is essentially flat in the non-gas-filled state and thus does not interfere with the flow of gas through the vent opening O. 
   In the case of a collision, if the controller coupled through an electrical connecting line  14  find that it is advantageous to close the vent opening O for the production of an optimum internal pressure in the interior IR of the gas bag A, the gas source  1  is ignited in the manner described in connection with  FIG. 1 . Gas is thereby released which fills the inflatable element  2  so that the inflatable element expands in a radial direction R, i.e., perpendicular to the longitudinal direction E, whereupon the rip seam  29  opens, as seen in  FIG. 4   b . 
   The filler tube  2  extends in its longitudinal direction E substantially perpendicular to the vent opening O through which the inflatable element  2  reaches. The filler tube applies its circumferential surface (formed by the envelope parts  21  and  22 ) against the periphery of the vent opening O so that the vent opening is closed. 
   When the two end faces  25  and  26  of the inflatable element  2  are closed in a gas-tight manner as described in  FIG. 1 , the vent opening O is likewise closed up. 
     FIGS. 5   a  and  5   b  shows another embodiment in which the difference from the embodiment of  FIGS. 4   a  and  4   b  is the fact that the one end  26 ′ (behind the rip seam  29 ) of the inflatable element  2  is not closed with a long-lasting seam (such as the seam  26  in  FIGS. 4   a  and  4   b ). 
   Therefore, after the inflatable element  2  in the form of a filler tube is filled with gas and after the bursting of the rip seam  29 , the gas in the inflatable element  2  can escape again through the one end  26 ′ so that the closing of the vent opening O by the inflatable element  2  is only momentary. The vent opening is reopened again by the escape of gas from the inflatable element and by the deflation of the inflatable element  2 . 
   In  FIGS. 7A ,  7 B, and  7 C, various possible arrangements of the vent opening are represented. One example is on the airbag module, namely a first position P 1  (shown in  FIG. 7A ) on the gas bag A in which, when the gas bag A is in the inflated state, the first position is slightly outside of and in the vicinity of the module housing M, which serves to accommodate the gas bag A as well as the associated gas generator G (as seen in  FIG. 6 ). Another example is a second position P 2  (shown in  FIG. 7B ) on the gas bag A, which is at the maximum distance from the module housing M in the inflated state of the gas bag. A third position P 3  (shown in  FIG. 7C ) shows a possible arrangement of the vent opening on the module housing M beneath the inflation mouth B of the gas bag, through which gases coming from a gas generator can enter the gas bag A. At each of the three positions P 1 , P 2 , P 3  of a vent opening on the gas bag, a suitable position of the associated inflatable element  2  (which here simultaneously forms the covering part for the vent opening), their corresponding gas source  1 , and their corresponding electrical connecting line  14  are shown by way of example. 
   In the case of the arrangement of the gas source  1  and the inflatable element  2  to cover a vent opening at the position P 3  on the module housing, the gas source  1  may be preferably arranged in the vicinity of the gas generator that serves for inflating the gas bag A and is to be contained in the module housing M. 
   In the case of a vent opening provided at the gas bag A or on its envelope itself, the vent opening can be preferably situated at a position P 2  near the module housing M—with respect to the inflated state of the gas bag A—so that gases issuing from the vent opening do not flow against the vehicle&#39;s occupant who is to be protected by the gas bag A. 
   The gas source  1  of the inflatable element  2  can be arranged as closely as possible at the position P 1 , P 2  or P 3  of the vent opening so as to permit control of the discharge cross section of the vent opening by an inflatable element  2  of the smallest possible size. An inflatable element  2  which can be filled with a small amount of gas offers the advantage that the associated gas source  1  can be made correspondingly small and light. 
   In the embodiments described above, the vent opening O, which can be closed at least partially by means of the covering part and thus on the airbag module itself with regard to its outlet cross section, is configured in each case on the airbag module itself, namely on a component of the airbag module, such as the gas bag A or the module housing M. Alternatively, the vent opening O, which can be at least partially closed and thus variable in its outlet cross section, can also be provided on a part of the motor vehicle outside of the airbag module, e.g., on a seat back in the case of a side airbag module, and can be in fluid connection with the airbag module through a gas-conducting connection. 
   The priority application, German Patent Application No. 10 2005 039 418.3, filed on Aug. 16, 2005, including the specification, drawings, claims, and abstract, is incorporated herein by reference in its entirety. 
   Given the disclosure of the present invention, one versed in the art would appreciate that there may be other embodiments and modifications within the scope and spirit of the invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is to be defined as set forth in the following claims.