Abstract:
An airbag arrangement for a motor vehicle includes an airbag deployable in a direction to protect a vehicle occupant and an arrangement for limiting the unfolding impulse of the airbag upon an obstacle placed in a deployment path of the airbag to reduce the unfolding impulse transferred to the obstacle. The limitation arrangement, which can be, for example, a sheath, aperture in the airbag, can respond to the resistance of the occupant located in the deployment path, which is outside a normal seating position, or respond to a lack of resistance from the passenger. As the limitation arrangement limits the unfolding impulse of the airbag, it reduces the maximum unfolding impulse transferable to the occupant located outside the normal seating, in the deploying path.

Description:
BACKGROUND  
         [0001]    An airbag for motor vehicles is designed to protect a vehicle occupant in the event of an accident. Problematic situations arise in cases where the vehicle occupant is not in his or her normal sitting position when the airbag deploys. Such situations, also known as “out of position” or OOP cases, are particularly significant for children who are not accommodated as prescribed in children&#39;s seats. The present invention addresses this problem.  
         SUMMARY OF THE INVENTION  
         [0002]    The present invention relates to an airbag arrangement for a motor vehicle having at least one inflatable airbag deployable in a direction to protect a vehicle occupant, and at least one arrangement associated with the airbag for limiting an unfolding impulse of the airbag upon an obstacle placed in a deployment path of the airbag to reduce the unfolding impulse transferred to the obstacle.  
           [0003]    Under a normal situation, the airbag is inflated in the direction to intercept the occupant to cushion the impact. The limiting arrangement for limiting the inflating impulse of the airbag can be influenced by an obstacle, such as the occupant. The limiting arrangement can reduce the inflating impulse directed to the obstacle, which is located in the path of the airbag expansion or movement.  
           [0004]    The limiting arrangement is designed to prevent the airbag from deploying its full unfolding impulse in the OOP cases, i.e., when the respective vehicle occupant is out of his normal position and situated in the path of the airbag deployment, but allows full unfolding impulse in the normal unimpeded situation, i.e., when the vehicle occupant is in his normal position. Since an obstacle, such as a vehicle occupant, influences the limitation arrangement, it automatically recognizes the OOP cases, whereupon the present limiting arrangement thereof automatically reduces the unfolding impulse of the airbag.  
           [0005]    The limitation arrangement can be formed such that it responds based on the resistance of the obstacle located outside the normal seating position, in the deployment path. The resistance created by the obstacle against the deploying airbag thus controls the unfolding or inflating impulse. Since the limitation arrangement responds to the obstacle this way, the occupant who is not in his or her normal sitting position and located in the deployment path of the airbag triggers the response of the limitation arrangement to reduce the inflation force of the airbag.  
           [0006]    Alternatively, it is also possible according to the present invention for the limitation arrangement to be formed such that it responds to the lack of resistance from the occupant. In this case, the limitation arrangement can detect an OOP situation by the lack of resistance, which is normally present if the occupant is properly located in the normal seating position. The present airbag arrangement allows a greater protection for the respective vehicle occupant, even in the OOP cases.  
           [0007]    In one embodiment of the invention, the limitation arrangement can comprise the airbag sheath. The airbag sheath, in the case of a folded airbag, can be made to have a lower degree of unfolding in one direction, e.g., in the direction of deployment, than approximately perpendicular to that direction.  
           [0008]    It is therefore possible to achieve a limitation of the unfolding impulse of the airbag sheath and thus a reduction in its inflation force without any additional means, simply through the uneven degree of unfolding of the airbag, uneven particularly with respect to the direction of deployment. The inflation of the airbag is substantially harmonized by the lower degree of unfolding in the direction of airbag deployment so that the inflation process is associated with a substantially lower force or drive. Here, the airbag is inflated predominantly in the direction of deployment due to the higher degree of unfolding perpendicular to the direction of deployment. The airbag is preferably folded together such that it has a large expansion perpendicular to the direction of deployment and takes up at least the substantial part of the space available in this direction. This allows an extremely areal arrangement of the folded airbag to be achieved, which substantially reduces its unfolding impulse. The direction of the lower degree of unfolding does not have to agree exactly with the direction of deployment, but can also deviate therefrom.  
           [0009]    The folded airbag can here be arranged areally along a contact surface located in the deployment path and has, in particular, areal contact to the contact surface. The contact surface preferably extends at least approximately perpendicular to the direction of deployment.  
           [0010]    It is further preferred to have the contact surface formed by an airbag cover. The airbag can, for example, be arranged at or in a vehicle seat, with a seat cover provided as the airbag cover, which is initially expandable and which can subsequently be ripped open, particularly by the inflation of the airbag. The seat cover can here be provided with a ripping seam.  
           [0011]    With an expandable seat cover, the airbag arranged according to the invention can be positioned under the seat cover in a favorable manner with respect to the OOP case at the beginning of the inflation process before it deploys further by the ripping open of the seat cover.  
           [0012]    According to a further preferred embodiment of the invention, the limitation arrangement can be configured such that when the obstacle is located outside the normal seating position, in the deployment path, the obstacle blocks the deployment path to limit the space for deploying the airbag. The limited space configures the airbag to prevent the airbag from reaching a threshold pressure in the airbag, which is only reachable in a normal protection case resulting from opposite external reaction forces generated when the occupant is in a normal seating position.  
           [0013]    The inflating airbag thus can be under less stress in the OOP case than in the normal protection case. For example, in the case of a side airbag arranged at the side of the backrest of a vehicle seat, the high pressure required to cancel the limitation is achieved in the airbag by the reaction forces exerted by the occupant in his normal position and the side panel of the vehicle when the airbag forces its way between the vehicle occupant and the side panel during inflation.  
           [0014]    These reaction forces are not present in the OOP case so that the pressure build-up required to break through the limitation is not carried out in the airbag and the airbag is inflated within the limitation, whereby the unfolding impulse and thus the inflation force of the airbag is reduced.  
           [0015]    In another embodiment according to the present invention, the limitation arrangement is formed by a limitation sheath surrounding the folded airbag at least partially, and whose maximum expandability in the direction of deployment is smaller than that of the airbag. The limitation sheath can be attached to that assembly of the vehicle at or in which the airbag is arranged, for example at a vehicle seat or a seat cover. Alternatively, the limitation sheath can also be attached to the airbag itself. It is further possible to provide the limitation sheath as a component of the airbag.  
           [0016]    According to another embodiment of the present invention, the airbag comprises at least two sections, a primary section and a secondary section, that are inflatable sequentially one after another. The limitation arrangement can comprise at least one valve between these sections. The valve can be closed when the folded airbag is blocked by the resistance of the obstacle located outside the normal position and can be opened by the inflation of the primary section of the airbag, which is inflatable first if there is no such resistance.  
           [0017]    A vehicle occupant located outside his normal position automatically ensures that the valve arranged between the two part volumes of the airbag remains closed. The inflation volume of the airbag thus remains limited to the volume of the primary section, whereby the inflation force of the airbag is reduced in a manner advantageous in the OOP case. The valve can be closed by the folded secondary section of the airbag.  
           [0018]    The valve can be formed by a nozzle section formed with at least one aperture. The nozzle section can be pushed over, folded, over, flipped over or bent over, in particular against the direction of deployment, to block the aperture. This nozzle section can be formed, in particular, tubular, hose, or snorkel configuration. The cross-section of this section can be approximately circular, but generally can have any geometry deviating from a circular shape.  
           [0019]    The nozzle section forming the valve can be formed at a partition wall arranged in the airbag sheath, separating the two sections of the airbag from one another. The partition wall can be a material layer sewn into the airbag sheath.  
           [0020]    According to a further variant of the invention, the limitation arrangement can comprise at least one discharge aperture formed in the airbag sheath. The aperture is closed in the normal protection position, but allows gas to escape when an obstacle blocks the airbag.  
           [0021]    The gas can be blown into the airbag with at least one gas generator to inflate the airbag. The gas can escape from the airbag through the discharge aperture in the OOP case, whereby the unfolding impulse of the airbag is reduced. The closing the discharge opening in the normal protection case ensures that the airbag can be fully inflated and can assume its protective position.  
           [0022]    The limitation arrangement can further include a closing arrangement for closing the discharge aperture arranged in the airbag or airbag sheath. The closing arrangement is configured to close the aperture when the airbag is deployed without the obstacle in the deployment path. That is, it is switchable to at least partially close the aperture when unfolding of the airbag increases in the normal protection case.  
           [0023]    This way, a reversible closure for the discharge opening is created by the unfolding of the airbag, with such closure being automatically switched to the state closing the discharge aperture in the normal protection case in which the airbag can unfold without hindrance. The unfolding of the airbag is blocked in the OOP case by the obstacle formed by the occupant located outside his normal position so that the closing arrangement cannot be switched to the closing position. The discharge aperture consequently remains open in the OOP case so that gas can escape from the airbag, whereby its unfolding impulse is reduced.  
           [0024]    The closing arrangement can comprises at least one material layer connected, in particular sewn, to the airbag sheath, with the connection being releasable at least in regions by the inflating of the airbag.  
           [0025]    It is advantageous here for a connection releasable by the inflating of the airbag to be provided in a region of the airbag located at the front in the direction of deployment, while the material layer is fixed to the airbag sheath in an inflation-resistant manner in a region located at the back in the direction of deployment.  
           [0026]    In another embodiment, the closing arrangement, formed in particular by a material layer, is connected in an inflation-resistant manner to the airbag sheath, with the material layer contacting the airbag sheath and closing the discharge aperture at least in part in the normal protection case with the airbag inflated at least in part.  
           [0027]    It can be achieved this way, without releasable connections between the closing arrangement, i.e., the material layer, and the airbag sheath and by a corresponding design and/or arrangement of the material layer, that the material layer contacts the airbag sheath and closes the discharge aperture at an advanced stage of the inflation process. The advanced stage of the inflation process required for a closing of the discharge aperture is not achieved in the OOP case due to the vehicle occupant forming an obstacle, which is in the way of the deploying airbag so that the discharge aperture remains in an unclosed state and gas can escape from the airbag, whereby the unfolding impulse of the airbag and thus its inflation force is reduced.  
           [0028]    According to a further variant embodiment according to the invention, the discharge aperture can be moved away from an external closing surface at least partly closing the discharge aperture in the normal protection case by the inflation of the airbag when the obstacle is outside the normal position.  
           [0029]    The limitation arrangement formed by the discharge opening thus responds here to the lack of resistance of the obstacle by creating a gas escape possibility by the discharge aperture moving away from the closing surface, whereby the unfolding impulse of the airbag is reduced. In contrast, when a vehicle occupant assuming his or her normal position forms the obstacle in the normal protection case, the airbag cannot deploy in a manner such that the discharge aperture is moved away from the closing surface. Since the discharge aperture remains at least partly closed in the normal protection case, the airbag can be inflated in the preset manner and meet its protective function.  
           [0030]    The closing surface can be formed by the assembly of the vehicle at or in which the airbag is arranged, for example by a side panel of the vehicle or by a vehicle seat.  
           [0031]    The airbag arrangement can be a side airbag arrangement integrated in a vehicle seat or in a vehicle side panel. The invention can, however, generally be employed with any imaginable airbag arrangement, e.g., in conjunction with a front airbag arrangement for the driver or front-seat passenger or with airbag arrangements arranged in the corresponding positions relative to a vehicle seat in order to protect certain body regions of an occupant, e.g., the knee or the feet.  
           [0032]    The various embodiments and features of the limitation arrangements described above, and in detail below, can be combined with one another. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    These and other features, aspects, and advantages of the present invention will become more apparent from the following description, appended claims, and accompanying exemplary embodiments shown in the drawings, which are briefly described below.  
         [0034]    [0034]FIGS. 1 a - 1   c  illustrate an airbag arrangement according to an embodiment of the invention serving as a side airbag and integrated in a vehicle seat.  
         [0035]    [0035]FIGS. 2 a - 2   c  illustrate an airbag arrangement according to another embodiment of the invention serving as a side airbag.  
         [0036]    [0036]FIGS. 3 a  and  3   b  illustrate an airbag arrangement according to yet another embodiment of the invention serving as a side airbag.  
         [0037]    [0037]FIGS. 4 a  and  4   b  illustrate an airbag arrangement according to yet another embodiment of the invention serving as a side airbag;  
         [0038]    [0038]FIGS. 5 a  and  5   b  illustrate an airbag arrangement according to yet another embodiment of the invention serving as a front airbag.  
         [0039]    [0039]FIGS. 6 a  and  6   b  illustrate an airbag arrangement according to yet another embodiment of the invention serving as a front airbag.  
         [0040]    [0040]FIGS. 7 a  and  7   b  illustrate an airbag arrangement according to yet another embodiment of the invention serving as a side airbag and integrated in a vehicle side panel. 
     
    
     DETAILED DESCRIPTION  
       [0041]    The airbag arrangement arranged according to FIG. 1 a , formed in a projecting side region of a backrest of a vehicle seat  26 , comprises a gas generator  11 , an airbag  12 , and a limitation sheath  16 . The sheath  16  is provided with a ripping seam  62 , surrounds the airbag  12 , and serves as an arrangement to limit the unfolding impulse of the airbag  12 . The seat cover  24  limits the vehicle seat  26  in the direction of deployment A of the airbag  12 .  
         [0042]    [0042]FIG. 1 b  shows the OOP case in which a vehicle occupant  14  does not assume his normal position, but is located in the deployment path of the airbag  12 , and thus forms an obstacle to the deploying airbag  12 . When the gas generator  11  is triggered in the event of an accident, the airbag  12  deploys and expands the limitation sheath  16 , ripping open the seat cover  24  to reveal the sheath  16 . As no force, directed perpendicularly to the direction of deployment A, is exerted on the deploying airbag  12 , only a comparatively low pressure P 1  is built up in the airbag  12 . Thus, the unfolding impulse or the inflation force of the airbag  12  is reduced relative to the normal protection case, which is explained below. The expansion geometry of the airbag  12  is limited in the OOP case by the limitation sheath  16 , whose maximum expandability in the direction of deployment A is smaller than that of the airbag  12 .  
         [0043]    In the normal protection case, which is shown in FIG. 1 c , the airbag  12  must force its way between the vehicle occupant  14  and the vehicle side panel  54  so that forces F 1 , F 2 , directed perpendicularly to the direction of deployment A, exert an effect on the deploying airbag. The airbag  12  is thus under a stronger load than in the OOP case, whereby a pressure P 2 &gt;P 1  is built up in the airbag  12 . The ripping seam  62  (see FIG. 1 a ) of the limitation sheath  16  can be torn open by the deploying airbag because of the higher inner pressure P 2 , whereby the limitation of the expansion geometry effective in the OOP case (see FIG. 1 b ) is overcome. The airbag  12  can thus move by inflation into its protective position in which the vehicle occupant  14  is protected from the side impact.  
         [0044]    The airbag arrangement according to the invention does not pose problem for the occupant  14  located in the deployment path of the airbag  12 , i.e., outside the normal sitting position, due to the limitation of the expansion geometry of the airbag  12  posed by the limitation sheath  16  in the OOP case. In this case, the unfolding impulse and thus the inflation force of the airbag  12  is reduced.  
         [0045]    [0045]FIGS. 2 a - 2   c  show an airbag arrangement also arranged at the side in a backrest of a vehicle seat  26 . Here, the airbag arrangement comprises an airbag  12  having an airbag sheath  18  and a gas generator  11 . FIG. 2 b  shows a horizontal section along the line  11   b - 11   b  of FIG. 2 a  in the region of the airbag arrangement.  
         [0046]    No additional means for limiting the unfolding impulse are needed in this embodiment. The limitation arrangement according to the invention is formed in this case by the arrangement of the airbag sheath  18 .  
         [0047]    The airbag  12  is arranged folded together at the vehicle seat  26  in the starting condition according to FIGS. 2 a  and  2   b  such that it contacts the inner side  22  of the seat cover  24  in an areal manner. The airbag  12  is arranged so that it is has the largest possible, areal expansion in a plane extending at least approximately perpendicular to the direction of deployment A. The airbag  12  is therefore already unfolded to a high degree in this plane and thus has a much higher degree of unfolding in this plane, i.e., in directions approximately perpendicular to the direction of deployment A, than in the direction of deployment A.  
         [0048]    [0048]FIG. 2 b  shows the folding of the airbag  12  in a horizontal section. As a result of the extensive or complete unfolding of the airbag  12  approximately perpendicular to the direction of deployment A, when the airbag  12  is inflated, its unfolding is carried out approximately only in one dimension, namely in the direction of deployment A.  
         [0049]    The seat cover  24  has sufficient expandability so that the airbag  12  can first be positioned below the seat cover, as is shown in FIG. 2 c , before the gas generator  12  is triggered. When the seat cover  24  is ripped open from a certain inflation pressure of the airbag  12 , the unfolding impulse and thus the inflation force of the airbag  12  already deploying in a partly inflated state is substantially reduced with respect to an airbag with differently configured limitation arrangement disclosed here. And the folded airbag/seat cover combination forms a compact package.  
         [0050]    The areal arrangement of the airbag  12  according to the invention results in a high harmonization of the inflation procedure, whereby the inflation of the airbag  12  is carried out in a substantially less aggressive manner. The seat cover  24  can be provided with one or more ripping seams by means of which the point in time of the ripping can be preset directly.  
         [0051]    In the embodiment of the invention according to FIGS. 3 a  and  3   b , the arrangement for limiting the unfolding impulse is formed by a valve arrangement or valve  16 . The valve  16  is arranged between a primary section  28  and a secondary section  32  of the airbag  12 . These two sections  28 ,  32  of the airbag or the airbag sheath  18  are separated from one another by a separating layer  37  in the form of a material layer sewn on the airbag sheath  18  at connecting points  31 . The layer  37  is thus a sheath section of the primary section  28  and of the secondary section  32  of the airbag  12  simultaneously.  
         [0052]    The valve  16  is formed by a hose or nozzle section  34  of the layer  37  pushed on or over against the direction of deployment (A) whose free end, which is directed downstream toward the back, in the direction of employment A, and which faces the gas generator  11 , is provided with a port  36 . The free discharge cross-section of the nozzle section  34  can generally have any desired shape and be, for example, circular in shape.  
         [0053]    In the unfolded state according to FIG. 3 a , the valve  16  is closed by the folded sheath of the secondary section  32 . Gas emitted after the triggering of the gas generator  11 , initially in the primary section  28 , flows according to the arrows in FIG. 3 a  into the pocket-like regions to the side of the nozle section  34 .  
         [0054]    In the OOP case, according to FIG. 3 a , the valve  16  cannot free open since the folded secondary section  32  is in the way and cannot unfold due to the occupant  14  blocking the airbag, as shown in FIG. 3 a . The valve  16  is thus fixed in its closed state by the resistance of the vehicle occupant  14 . As a result, the inflation volume of the airbag  12  is restricted to the part volume of the primary section  28  in the OOP case, whereby the unfolding impulse and thus the inflation force of the airbag  12  is reduced.  
         [0055]    In the normal protection case according to FIG. 3 b , the vehicle occupant  14  is not in the way of the unfolding of the secondary section  32 . The valve  16  can therefore be opened by pushing off the nozzle  34  due to the pressure building up in the primary volume  28  so that the gas can flow into the secondary section  32  via the aperture  36  in the layer  37 , as is indicated by the arrows in FIG. 3 b.    
         [0056]    The valve  16  can also be shaped differently according to the invention and have, for example, the form of a tube, hose, or snorkel. It is also possible to provide different valve mechanisms and to realize the valve function by gills or ripping seams, for example.  
         [0057]    In the embodiment of the invention according to FIGS. 4 a  and  4   b , the arrangement for limiting the unfolding impulse is formed by a discharge aperture  42  formed in the airbag sheath  18  and by a closing arrangement  44  comprising a material layer  46  arranged in the airbag sheath  18 . The material layer  46  is releasably connected, for example, sewn, to the airbag sheath  18  with its front end in the direction of deployment A such that it rips off from the airbag sheath  18  in the unhindered unfolding of the airbag  12 .  
         [0058]    In an OOP case according to FIG. 4 a , the airbag  12  cannot unfold unhindered after the triggering of the gas generator since the vehicle occupant  14  forming an obstacle is in its way. The length of the material layer  46  of the closing arrangement  44  is dimensioned with respect to typical OOP cases such that the limited deployment possibility of the airbag  12  does not activate an unfolding of the airbag sheath  18  sufficient to release the connection  48 . As a result, the material layer  46  remains in a discharge position inside the airbag  12  in which the gas emitted by the generator  11  into the airbag  12  can escape via the discharge opening  42  of the limitation arrangement. The unfolding impulse and thus the inflation force of the airbag  12  is reduced due to this gas escape possibility given in the OOP case.  
         [0059]    Referring to FIG. 4 b , in the normal protection case, the material layer  46  is arranged in the airbag  12  and fixed in an inflation-resistant manner to the airbag sheath  18  at a rear region in the direction of deployment A such that the material layer  46  is laid over the discharge aperture  42  with FIG. 4 b  after the separation of the releasable connection  48  by the unhindered unfolding of the airbag  12 . The material  46  is thus automatically switched from its discharge position into a closing position, closing the discharge aperture  42  by the increasing unfolding of the airbag  12  possible in the normal protection case. A gas escape possibility is thereby no longer there so that the airbag  12  can be fully inflated and can move into its protective position.  
         [0060]    In the embodiment of the invention according to FIGS. 5 a  and  5   b , which is a front airbag arrangement, two or more discharge apertures  42  are formed in the airbag sheath  18  spread around the gas generator  11 . A material layer  46  of a closing arrangement arranged in the airbag sheath  18  is associated with each discharge aperture  42 . The ends of the material layers  46  in the region of the gas generator  11  are fixed in an inflation-resistant manner to the airbag sheath  18 . The other ends of the material layers  46  are releasably connected, for example via a ripping seam, to a region of the airbag sheath  18 , which is at the front in the direction of deployment A, at a connecting point  48 .  
         [0061]    The material layers  46  have at least one port  43  respectively in the region of the connecting point  48  and the gas emitted by the gas generator  11  into the airbag  12  in the OOP case according to FIG. 5 a  can reach the other side of the material layer  46  via the discharge opening  43  and can thus escape from the airbag  12  via the respective discharge aperture  42 , as is indicated by the arrows in FIG. 5 a . Generally, the ports  43  of the material layers  46  can also be provided at different positions to the ones shown.  
         [0062]    In the OOP case, the vehicle occupant  14  forming an obstacle  14  prevents a movement of the front region of the airbag sheath  18  in the direction of deployment A so that the connections  48  between this region of the airbag sheath  18  and the material layers  46  remain intact. A reduction in the unfolding impulse and thus of the inflation force of the airbag  12  is achieved due to the gas escape possibilities via the ports  43  and the discharge apertures  42 .  
         [0063]    Referring to FIG. 5 b , in the normal protection case, the connections  48  between the front region of the airbag sheath  18  and the material layers  46  are released with an unhindered unfolding of the airbag  12 , with the material layers  46  thereupon being laid over the discharge apertures  42  and closing them so that the airbag  12  can be fully inflated.  
         [0064]    In the embodiment of the invention according to FIGS. 6 a  and  6   b , the closing arrangements  44  of the limitation arrangements according to the invention comprise in each case a material layer  46  connected to the airbag sheath  18  by sewing in such a fixed manner that the connection cannot be released by the unfolding of the airbag  12 .  
         [0065]    The limitation of the unfolding impulse of the airbag  12  is carried out here by the material layers  46  being respectively arranged in the region of a discharge aperture  42  formed in the airbag sheath  18  and by the material layers  46  being laid over the discharge outlets  42  from a certain unfolding stage.  
         [0066]    [0066]FIG. 6 a  shows the areally deployed status of the airbag  12 , whose airbag sheath  18  consists of two essentially circular part sheaths  18   a ,  18   b , which are sewn together via a peripheral connecting seam  47  and which lie on top of one another in the deployed state according to FIG. 6 a.    
         [0067]    As is also shown in FIG. 6 b , in which a section of the at least partly inflated airbag  12  is represented, the connecting seam  47  is interrupted by the discharge apertures  42 , with the material layer  46  respectively fixed to the part sheaths  18   a ,  18   b  via connecting seams extending over and beyond the discharge aperture  42 .  
         [0068]    The material layers  46  are folded together in the folded state of the airbag  12  such that they do not close the discharge apertures  42 . Gas emitted by the gas generator  11  into the airbag  12  can thus escape via the discharge apertures  42  at the beginning of the inflation procedure.  
         [0069]    Since the airbag  12  can unfold without hindrance in the normal protection case, the material layers  46  are also unfolded when the airbag sheath  18  unfolds. When a certain advanced inflation stage of the airbag  12  is reached, the material layers  46  are laid over the discharge apertures  42 .  
         [0070]    Since the discharge aperture  42  are closed from this point in time by the material layers  46  that thus contact the airbag sheath  18  at the inside, the airbag  12  can be fully inflated in the normal protection case.  
         [0071]    In the OOP case, in contrast, the airbag  12  is prevented from unfolding freely by a vehicle occupant (not shown) forming an obstacle. The material layers  46  are also not fully unfolded so that the discharge apertures  42  remain open or are only closed later. The unfolding impulse and thus the inflation force of the airbag  12  is reduced in this way in the OOP case.  
         [0072]    The material layers  46  thus form closing flaps for the discharge apertures  42 . The flaps  46  can be controlled by the unfolding of the airbag  12  and can be switched from a folded discharge position into a closing position closing the discharge apertures by the increasing unfolding of the airbag  12 .  
         [0073]    While in the embodiments of the invention described above, the arrangement for the limitation of the unfolding impulse responds in each case to the existing resistance of the vehicle occupant located outside his normal position, the situation applies in the embodiment of the invention according to FIGS. 7 a  and  7   b  where the limitation arrangement  16  responds to the lack of resistance of the vehicle occupant  14  located in the normal position.  
         [0074]    [0074]FIG. 7 a  shows an OOP case in which the airbag  12 , unlike in the normal protection case shown in FIG. 7 b , can move away from a side panel  54  of the vehicle without hindrance. The unfolding impulse or the inflation force of the airbag  12  is, however, reduced by at least one discharge aperture  42  in the airbag sheath  18 , which aperture forms the limitation arrangement  16  according to the invention, and via which gas can escape from the airbag  12  as indicated by the arrow in FIG. 7 a.    
         [0075]    The discharge aperture  42  is arranged such that it remains closed by a closing surface  52 , which is formed by the vehicle side panel  54  and at which the airbag  12  is supported, in the normal protection case according to FIG. 7 b  during the inflation of the airbag  12  or in the case of a stress by the occupant  14 .  
         [0076]    The protective function of the airbag  12  is thus not impaired by the discharge aperture  42  in the normal protection case, whereas a gas escape possibility, which results in a reduction in the unfolding impulse or the inflation force, is provided by the release of the discharge aperture  42  due to the lack of the occupant resistance in the OOP case according to FIG. 7 a.    
         [0077]    The provision of at least one valve arrangement and/or discharge aperture at the airbag such as was described above with reference to the embodiments of FIGS. 3 a ,  3   b ,  4   a ,  4   b ,  5   a ,  5   b ,  6   a ,  6   b  and  7   a ,  7   b , represents in each case a specific embodiment of a further, independent inventive step. This inventive step generally comprises providing an airbag with at least one valve arrangement or gas escape possibility controllable in time by the unfolding of the airbag. The time control means that the gas outlet or outlets are open at the start of the unfolding and are at least partly closed from a certain point in time during unfolding, with closing means of any design generally being able to be provided here. This time control is generally independent of the presence or non-presence of an obstacle such as a vehicle occupant. This further inventive step therefore can be applied to the present embodiments described above in connection with an obstacle.  
         [0078]    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 present 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 accordingly is to be defined as set forth in the appended claims.  
         [0079]    The disclosure of the priority application DE 100 18 170.8, filed Apr. 12, 2000 in Germany, in its entirety, including the drawings, claims, and the specification thereof, is incorporated herein by reference.