VEHICLE OCCUPANT PROTECTION SYSTEM AND METHOD FOR PROTECTING A VEHICLE OCCUPANT

Abstract

Vehicle occupant protection system (10) comprising a gas bag module (14) comprising a gas bag (12) with a first and a second retaining strap (32, 38) running inside the gas bag (12) and a module-mounted actuator unit (36), wherein the first retaining strap (32) is permanently attached to a gasbag-side attachment point (33) on a front wall (24) of the gasbag (12) and detachably fixed to the actuator unit (36) at a first module-side attachment point (34), and the second retaining strap (38) is attached to the module at a second module-side attachment point (40) and is connected to the first retaining strap (32) at a retaining strap connection point (42), wherein a decoupling device (44) is provided in the course of the second retaining strap (38) between the second module-side attachment point (40) and the retaining strap connection point (42), which triggers when a predetermined force threshold is exceeded, wherein activation of the actuator unit (36) releases the first retaining strap (32) on the module side and wherein the decoupling device (44) is only in the force flow between the second module-side attachment point (40) of the second retaining strap (38) and the gas bag-side attachment point (33) of the first retaining strap (32) when the actuator unit (36) is activated, characterized in that a venting device (28) is provided, to which a venting retaining strap (46) running inside (30) the gas bag (12) engages, which is detachably connected to the actuator unit (36).

Description

[0001] The invention relates to a vehicle occupant protection system with a gasbag module and a method for protecting a vehicle occupant.

[0002] Gasbags in a gasbag module mounted in a vehicle interior are generally optimized for a specific distance between a vehicle occupant and the gasbag module. Solutions are known to compensate for certain, relatively small variations in seat distance, which can occur, for example, when a smaller occupant moves their seat closer to the front of the vehicle than a larger occupant. In one solution, the gasbag volume is varied by using an actuator to release a retaining strap located inside the gasbag when it needs to inflate to a larger volume. It is also known to provide a venting device in the wall of the gasbag through which gas can be released from the interior, if necessary, to soften the gasbag and, for example, to make the impact of a smaller, lighter occupant less severe.

[0003] However, in autonomous vehicles, the freedom of movement for vehicle occupants within the interior is to be significantly increased. For example, it should be possible for occupants to adjust their seats to a comfortable position, in which the seat is considerably further away from the front of the vehicle than is currently possible for the driver and even the front passenger. Furthermore, it should often be possible to recline the seat backrest while driving to assume a sleeping position.

[0004] DE 10 2018 133 050 A1, for example, shows a front gas bag with two accessible contours with a retaining strap system, wherein an active actuating device for releasing a first retaining strap of the retaining strap system is provided and a fold is held by a tear seam which is only subjected to stress after activation of the actuating device.

[0005] Furthermore, DE 10 2018 133 051 A1 also shows a front gasbag with two accessible contours with a retaining strap and an electrically actuated activation device for releasing the retaining strap, wherein the retaining strap has several retaining strap sections connected to each other via a tear seam.

[0006] The object of the invention is to protect the vehicle occupant in a restraint situation by means of a gasbag, both in a normal driving position and, for example, in a comfort position, in particular by means of a flexibly deployable vehicle occupant protection system.

[0007] This problem is solved by a vehicle occupant protection system with the features of claim 1. The vehicle occupant protection system comprises a gasbag module, which includes a gasbag with a first and a second retaining strap running inside the gasbag and a module-mounted actuator unit. The first retaining strap is permanently attached to a front wall of the gasbag at a mounting point on the gasbag side and detachably fixed to the actuator unit at a first module-side mounting point. The second retaining strap is attached to the module at a second module-side mounting point and is connected to the first retaining strap at a retaining strap connection point. A decoupling device is provided along the second retaining strap between the second module-side mounting point and the retaining strap connection point, which triggers when a predetermined force threshold is exceeded.Activating the actuator unit releases the first retaining strap on the module side. The decoupling device is only in the force path between the second module-side attachment point of the second retaining strap and the gasbag-side attachment point of the first retaining strap when the actuator unit is activated.

[0008] The actuator unit is preferably a so-called tether activation unit, which, for example, includes a pyrotechnic explosive bolt that secures the first tether strap on the module side before the actuator unit is activated and is cut upon activation, thus releasing the first tether strap on the module side. The actuator unit could, of course, also be designed in other ways, for example, using a spring mechanism.

[0009] In this context, a module-mounted attachment also refers to a vehicle-mounted attachment, since the gas bag module is typically permanently and immovably installed in the vehicle. This module-mounted attachment can be, for example, to the housing of the gas bag module, to a gas generator within the gas bag module, or to a vehicle-mounted component in the immediate vicinity of the gas bag module.

[0010] The first retaining strap is preferably connected to the actuator unit only at its first module-side attachment point.

[0011] According to the invention, the decoupling device can only trigger when the actuator unit is activated, since only in this case does a sufficiently large force act on the decoupling device to make it possible to exceed the predetermined force threshold.

[0012] In general, the decoupling device is designed such that it has two parts that are connected to each other before the force threshold is exceeded, and which separate from each other when the force threshold is exceeded. Thus, the decoupling device can be, for example, a simple predetermined breaking point, such as a tear seam or a perforation, a deformable tab on a module-side attachment of the second retaining strap, or a more complex mechanical device. As a rule, release occurs directly through the application of a mechanical force exceeding the force threshold to the decoupling device.

[0013] The first retaining strap should be fixed to the inside of the front wall of the airbag. A shock-absorbing surface is formed on the front wall of the airbag, designed to catch a vehicle occupant who shifts forward in a restraint situation and is seated in a vehicle seat associated with the airbag module.

[0014] The invention can be implemented for a driver's gasbag module in a steering wheel as well as for a passenger's gasbag module, for example in a dashboard or other vehicle-mounted component, but is not limited to these applications.

[0015] If the actuator unit is not activated in a restraint situation, the first retaining strap advantageously determines the distance between the front wall of the airbag and the airbag module by its length between its first module-side attachment point and its airbag-side attachment point. The airbag is then filled with a first, smaller volume of filling gas. This filling gas is generally supplied by a gas generator in the airbag module. This procedure is desirable, for example, when the vehicle seat, and thus the vehicle occupant, is in a driving position relatively close to the airbag module, i.e., close to the steering wheel or the dashboard.

[0016] However, if the actuator unit is activated and the decoupling device is triggered in a containment situation, the first retaining strap is released and loses its influence over the shape and volume of the filled gas bag. The gas bag is then filled to a second, larger volume.

[0017] This can happen if the vehicle seat is in a position significantly further away from the gasbag module than in the driving position, or if the backrest of the vehicle seat is folded back, for example in a comfort position that can be assumed during autonomous driving.

[0018] In another possible scenario, during a containment situation, the actuator unit is activated, but the decoupling device does not trigger. In such a case, the gas bag is only filled to the first, smaller volume, as the first retaining strap remains fixed to the gas bag module. However, additional actions are possible, which can be triggered via the actuator unit and are described in more detail below, thus providing the option of additional procedural steps.

[0019] The first tether is usually an elongated, ribbon-shaped piece of fabric, especially made of gasbag fabric.

[0020] The second retaining strap is preferably a separate component from the first retaining strap, for example a woven strap, in particular made of gasbag fabric. Optionally, the second retaining strap is made of a different material or consists essentially of the decoupling device.

[0021] However, it would also be conceivable that the second safety strap merges seamlessly into the first at the connection point, thus forming a section of the first safety strap. In this case, the division between the first and second safety straps is virtually defined by the first module-side attachment point and the decoupling device, with the connection point being essentially any location between these two points.

[0022] The decoupling device can be bypassed when the actuator unit is not activated by ensuring that, in a safety strap run from the second module-side attachment point of the second safety strap via the safety strap connection point and the first module-side attachment point of the first safety strap on the actuator unit to the gas bag-side attachment point of the first safety strap, viewed in the direction of the gas bag-side attachment point of the first safety strap, the first module-side attachment point of the first safety strap is located after the safety strap connection point and the second module-side attachment point of the second safety strap.As long as the first retaining strap is connected to the gas bag module and thus to the vehicle via the actuator unit at the first module-side attachment point, all forces acting on the first retaining strap when it is tensioned between the front wall of the gas bag and the actuator unit are transferred into the vehicle via this attachment point and not transmitted to the second retaining strap and the decoupling device. This completely prevents any stress on the second retaining strap and, in particular, on the decoupling device. Therefore, in this case, it is also impossible for a force exceeding the force threshold to act on the decoupling device.

[0023] Another option is for the second retaining strap to be longer than the length of the first retaining strap between the first module-side attachment point and the strap connection point. If the first retaining strap is then tensioned between the front wall of the gas bag and the actuator unit, the second retaining strap remains slack, preventing any forces from acting on the decoupling device that exceed the force threshold.

[0024] When the actuator unit is activated, the forces acting on the first retaining strap also act on the decoupling device, since the first attachment point on the first retaining strap is no longer fixed to the vehicle. The crucial factor is whether the forces acting on the decoupling device exceed the force threshold or not. In the first case, the decoupling device is triggered, and the first retaining strap is completely released on the module side. In the second case, the first retaining strap remains fixed to the module side via the second retaining strap.

[0025] Preferably, the length of the second retaining strap and the length of the first retaining strap between the first module-side attachment point and the strap connection point are chosen to be as short as possible so that, in the case described above, when the actuator unit is activated but the decoupling device does not trigger, the total length of the retaining strap run from the second module-side attachment point of the second retaining strap to the gasbag-side attachment point of the first retaining strap increases only insignificantly compared to the length of the first retaining strap from the first module-side attachment point to the gasbag-side attachment point of the first retaining strap. For practical reasons, the volume of the gasbag when filled should be the same in both cases.

[0026] The force threshold is preferably selected such that, with the actuator unit activated, the first retaining strap exerts a force on the decoupling device exceeding the force threshold during an initial or intermediate phase of the gas bag's inflation, while in a final inflation phase, the force exerted by the first retaining strap on the decoupling device always remains below the force threshold. The final inflation phase is defined here as the period in which at least approximately 80% to 95% of the initial, smaller volume of the gas bag is already filled and the gas bag's deployment and positioning within the vehicle interior is complete, such that the gas bag has essentially achieved its intended shape and position.In particular, the movement of the front wall of the gasbag to its final position in the vehicle interior is already so far completed that no significant tensile forces are exerted on the first retaining strap.

[0027] If the actuator unit is activated at the beginning of the gas bag's inflation process, the moving front wall of the gas bag, moving away from the gas bag module inside the vehicle, exerts high forces on the first retaining strap, which are then transmitted to the decoupling device. This triggers the decoupling device, completely releasing the first retaining strap on the module side. The gas bag can then expand to its second, larger volume and inflate.

[0028] However, if the actuator unit is only activated at a point when the front wall of the gas bag has already essentially reached its final position, only minor tensile forces act on the first retaining strap, insufficient to trigger the decoupling device. Therefore, the first retaining strap remains fixed to the module and the vehicle via the second retaining strap and the second module-side attachment point. In this case, the gas bag's inflation is complete when it reaches its initial, smaller volume.

[0029] The first retaining strap may be limited to the length between the attachment point on the front wall of the gas bag and the connection point of the retaining strap with the second retaining strap.

[0030] In a preferred embodiment, however, the first retaining strap remains attached to the gasbag-side mounting point on the front wall at one end and at a second end to the gasbag wall, particularly also to the front wall, and the first module-side mounting point and the retaining strap connection point are located between the two ends of the first retaining strap. In this way, when the actuator unit is not activated or the decoupling device is not triggered, the tensile forces are transferred to the front wall at several points, thereby influencing the shape of the gasbag in its initial, smaller volume.

[0031] In this case, as described above, the length of the second retaining strap should be chosen to be longer than the length of the first retaining strap between the first module-side attachment point and the retaining strap connection point, so that when a tensile force acts on the section of the second retaining strap between the retaining strap connection point and the gasbag-side attachment point of the second end of the first retaining strap, no significant forces can act on the decoupling device.

[0032] The connection point of the first tether strap, and thus the connection to the second tether strap, can be located approximately in the middle of its length. This results in a V-shaped path for the first tether strap when the actuator unit is not activated, and a Y-shaped path when the actuator unit is activated but the decoupling device is not triggered. The stem of the Y, formed by the second tether strap, should be kept as short as possible.

[0033] In the preferred variant, the first retaining strap does not detach from the gasbag wall even in the event of restraint.

[0034] The only detachable fastenings are generally the first module-side fastening point of the first retaining strap on the actuator unit and the decoupling device on the second retaining strap.

[0035] The position of the decoupling device between the second module-side attachment point and the safety strap connection point can be chosen freely. For example, the decoupling device can be positioned directly at the second module-side attachment point or at the safety strap connection point. A simple seam designed as a tear seam could be used here. Alternatively, the decoupling device could be designed, for example, as a perforation along the second safety strap. Of course, any other form of decoupling device, even a more complex mechanism, can also be used.

[0036] According to the invention, a venting device is provided to which a venting retaining strap running inside the gas bag engages and which is detachably connected to the actuator unit. The venting device is formed, for example, by a vent opening in the gas bag wall, which is provided with a flap, wherein the vent opening is opened or closed by pulling on the venting retaining strap. This depends on the design of the venting device, whereby it is preferred here that the venting device, and thus the vent opening, remains closed as long as the venting retaining strap is under tension, and only when the venting retaining strap is released is the flap opened, the vent opening released, and thus the venting device opened.

[0037] The venting safety strap is preferably a component that is completely separate from the first and second safety straps.

[0038] The release of the venting strap by the actuator unit corresponds here to the additional action already described above, which can occur in a scenario in which the actuator unit is activated, but the decoupling device is not triggered.

[0039] Preferably, the venting device is designed such that the venting device is only opened when the venting catch strap is released by the actuator unit.

[0040] Opening or closing the venting device affects the rigidity of the airbag and thus the force that the airbag exerts on the impacting vehicle occupant. This is another parameter that can be varied in the vehicle occupant protection system according to the invention.

[0041] It has proven advantageous to open the venting device when a vehicle seat is provided that can assume a first and a second position, wherein the vehicle seat in the second position is located a factor of approximately 1.2 to 2.5, in particular a factor of approximately 1.5 to 2, further away from the gasbag module than in the first position, wherein the gasbag in the first position of the vehicle seat, when filled, assumes the first, smaller volume and in the second position of the vehicle seat, when filled, the second, larger volume.

[0042] As mentioned above, the first position of the vehicle seat corresponds to a normal driving position, in which, in particular, the occupant in the driver's seat operates the steering wheel. The second position corresponds to a comfort position, which can be assumed especially when the vehicle is driving autonomously, and in which the vehicle seat is, for example, so far away from the steering wheel that the occupant in the driver's seat can no longer operate the steering wheel. If necessary, the backrest of the vehicle seat can also be reclined in the comfort position, allowing the occupant to assume a sleeping position.

[0043] The different gasbag volumes allow the difference in distance to be compensated for, so that the vehicle occupant can be protected in a restraint situation in both seating positions.

[0044] This can be achieved using a method comprising the steps specified in claim 9. The method for protecting a vehicle occupant can be implemented, in particular, using a vehicle occupant protection system as described above. In a restraint situation that occurs when the vehicle seat is in the first, forward position, the gas bag of the gas bag module is inflated with the first, smaller volume. Furthermore, depending on the size of the vehicle occupant in the vehicle seat, the venting device of the gas bag is either open or closed. However, in a restraint situation that occurs when the vehicle seat is in the second, rearward position, the gas bag is always inflated with the second, larger volume, and the venting device is opened.

[0045] In this case, preferably in a restraint situation where the vehicle seat is in the first position, the actuator unit is always not activated or only activated in a final phase of the gas bag inflation, and the decoupling device does not trigger, whereas in a restraint situation where the vehicle seat is in the second position, the actuator unit is always activated and the decoupling device triggers, so that the first retaining strap is released on the module side.

[0046] This ensures that the gasbag only reaches the second, larger volume when the vehicle seat is in the second position.

[0047] If a venting device with a venting strap is provided, then in the vehicle occupant restraint system described above, the venting device is always opened in a restraint situation in the second seating position, thus softening the airbag, since the venting strap is always released on the module side when the actuator unit is activated. However, in a restraint situation that occurs when the vehicle seat is in the first seating position, the activation of the actuator unit determines whether the venting device opens or remains closed, i.e., whether the airbag is adjusted to be firmer or softer.

[0048] If a venting device is provided, a distinction between a larger and a smaller vehicle occupant in the vehicle seat preferably ensures that the actuator unit is activated in the final stage of the gas bag inflation if the occupant is the smaller size, and not activated if the occupant is the larger size. This ensures that a larger vehicle occupant can be safely restrained, while also ensuring that a smaller vehicle occupant does not experience excessively high restraint forces. The distinction between a smaller and a larger vehicle occupant can, for example, be based on standardized 50% and 95% dummies or standardized 5% and 50% dummies.

[0049] As described above, in the first position of the vehicle seat, the actuator unit is only activated and the first retaining strap only released when the force threshold of the decoupling device is no longer exceeded by the inflation of the airbag. The airbag therefore always only expands to its initial, smaller volume. Activating the actuator unit in this case results in the release of the venting retaining strap and the opening of the venting device. The associated slight increase in the volume of the airbag is negligible in practice.

[0050] The invention is described in more detail below with reference to an exemplary embodiment and the accompanying figures. The drawings show: - Fig. 1 a schematic representation of a vehicle occupant protection system according to the invention for carrying out a method according to the invention, with a vehicle seat which is in a first, forward position and a gas bag which is filled to a first, smaller volume, in a first restraint situation, wherein an actuator unit is not activated; - Fig. 2 the vehicle occupant protection system Fig. 1 in a second containment situation, with the actuator unit activated; - Fig. 3 the vehicle occupant protection system off Fig. 1 in a third restraint situation, wherein the vehicle seat is in a second, rear position of the vehicle seat and the gasbag is filled to a second, larger volume, with the actuator unit activated; - Fig. 4 a schematic representation of the vehicle occupant protection system Fig. 1 in a first embodiment, wherein the gas bag is shown during filling; - Fig. 4a an enlarged section from Fig. 4; - Fig. 5 a variant of the vehicle occupant protection system Fig. 4; - Fig. 6 a schematic representation of the vehicle occupant protection system Fig. 1 in a second embodiment, wherein the gas bag is shown during filling; - Fig. 7 to 9 the vehicle occupant protection system off Fig. 4 during the filling of the gas bag in the first containment situation; - Fig. 10 to 13 the vehicle occupant protection system off Fig. 4 during the filling of the gasbag in the second containment situation; and - Fig. 14 to 16 the vehicle occupant protection system off Fig. 4 during the filling of the gas bag in the third containment situation.

[0051] The Fig. Figures 1 to 3 show a vehicle occupant protection system 10 in three different restraint situations, whereby Fig. 1. an initial containment situation, Fig. 2 a second containment situation and Fig. 3 represents a third containment situation.

[0052] The vehicle occupant protection system 10 comprises a gas bag 12 which inflates with filling gas in a restraint situation. The gas bag 12 is part of a gas bag module 14 (not shown) which also includes a gas generator (not shown) that supplies the filling gas for the gas bag 12 in a known manner.

[0053] In the example shown here, the gasbag module 14 is incorporated into a steering wheel 16 of a vehicle, so that the gasbag 12 is designed as a driver's gasbag.

[0054] Fig. Figure 6 shows an embodiment in which the gasbag module 14 is arranged in an instrument panel 18 of the vehicle, wherein the gasbag 12 is designed as a passenger gasbag.

[0055] However, the general structure of the vehicle occupant protection system 10, its behavior in the different restraint situations, and thus also the procedure carried out with the vehicle occupant protection system 10 are identical for both embodiments.

[0056] A vehicle occupant 20 on a vehicle seat 22, which is assigned to the gas bag module 14, is caught in a restraint situation by the filled gas bag 12, whereby he plunges into an impact surface provided on a front wall 24 of the gas bag 12.

[0057] The vehicle seat 22, and thus the vehicle occupant 20, can be located at different distances d from the gasbag module 14, since the vehicle seat 22 is adjustable along a longitudinal direction of the vehicle. In the method described here for protecting a vehicle occupant 20, two distances d1, d2 are of interest, where each of the distances d1, d2 can represent a distance range, e.g., 20 to 50 cm.

[0058] The distance d1 describes a seating distance in which the vehicle seat 22 is positioned relatively close to the accelerator module 14, i.e., relatively close to the steering wheel 16 or the instrument panel 18. Such a seating distance is assumed, for example, in a driving situation in which the hands of the vehicle occupant 20 are on the steering wheel 16. When the vehicle seat 22 is at a seating distance d1, this is also referred to here as the first or front seating position or driving position.

[0059] The distance d2 describes a seat distance in which the vehicle seat 22 is significantly further from the steering wheel 16 or the instrument panel 18 than at distance d1. This position of the vehicle seat, also referred to here as the second or rear seat position or comfort position, is assumed, for example, in a comfort situation in which the vehicle is driving autonomously and the vehicle occupant 20 is not occupied with driving the vehicle. It is also conceivable that in the second seat position, a backrest 26 of the vehicle seat 22 is folded back. Here, it would also be possible that the vehicle seat 22 is closer to the airbag module 14 than distance d2, since the upper body of the vehicle occupant 20 is further away from the airbag module 14 due to the reclined position. It is therefore conceivable that in the comfort position only the upper body of the vehicle occupant 20 is at distance d2 from the airbag module 14.

[0060] It is possible that the distance d1 in particular may vary slightly, since a taller vehicle occupant 20 may adjust the vehicle seat 22 slightly further away from the front of the vehicle than a shorter vehicle occupant 20. However, this variation should not reach the distance d2 in the second, rear seat position.

[0061] The inflation behavior of the gasbag 12 varies depending on the seating position.

[0062] In the first seating position, when the gas bag module 14 is activated in a restraint situation, the gas bag 12 is always only filled to a first, smaller volume V1 (see Fig. 1 and Fig. 2), while in the second seating position, the gasbag 12 is always filled to a second, larger volume V2 when the gasbag module 14 is activated, in order to take into account the greater distance between the vehicle occupant 20 and the gasbag module 14 (see Fig. 3).

[0063] The gas bag 12 has a venting device 28 which can assume a closed and an open state, whereby in the open state (also referred to as open venting device 28) gas can escape from the interior 30 of the gas bag 12 into the environment.

[0064] If the vehicle seat 22 is in the first seating position, the ventilation device 28 is opened depending on the body size K1, K2 of the vehicle occupant 20 on the vehicle seat 22.

[0065] If the vehicle occupant 20 has a first body height K1 that is greater than a predetermined limit, the venting device 28 remains closed in the restraint situation. This results in the airbag 12 having sufficient rigidity to safely restrain the larger vehicle occupant 20.

[0066] If, however, the vehicle occupant 20 has a second body size K2 that is smaller than the specified limit value and thus smaller than the first body size K1, the venting device 28 is opened in the restraint situation so that the gas bag 12 becomes softer and the forces during immersion are reduced.

[0067] To determine the limit for body size, for example the values ​​of a 50% and a 95% dummy or the values ​​of a 5% and a 50% dummy are used.

[0068] Inside 30 of the gas bag 12, a first retaining strap 32 is arranged, which is permanently attached to the inside of the front wall 24 of the gas bag 12 at a gas bag-side attachment point 33 and which is attached on the module side at a first module-side attachment point 34 to a module-fixed actuator unit 36 ​​in such a way that it releases on the module side when the actuator unit 36 ​​is activated.

[0069] The actuator unit 36 ​​is, for example, a known tether activation unit (TAU) that may include an explosive bolt which is activated by a control signal from a control unit (not shown) and which then releases the first module-side attachment point 34 of the first retaining strap 32. If the actuator unit 36 ​​is not actuated, the first retaining strap 32 remains fixed to the module and thus to the vehicle at its first module-side attachment point 34.

[0070] A module-mounted attachment here refers to a vehicle-mounted attachment in the area of ​​the gas bag module 14, for example on a housing of the gas bag module 14 or on the gas generator of the gas bag module 14.

[0071] Furthermore, a second retaining strap 38 is arranged inside 30 of the gas bag 12, which is fixed to a second module-side attachment point 40 and is connected to the first retaining strap 32 at a retaining strap connection point 42.

[0072] A decoupling device 44 is arranged along the course of the second safety belt 38, which triggers when a predetermined force threshold is exceeded and then interrupts the safety belt's path along the second safety belt 38.

[0073] The decoupling device 44 can be designed in any way. In the present example, it is implemented by a tear seam, which is located either at the second module-side attachment point 40 of the second retaining strap 38 (see Fig. 4a) or at the lanyard connection point 42 (see Fig. 5) is provided for attaching the second safety strap 38. If the specified force threshold is exceeded, the tear seam releases, and the second safety strap 38 is detached at the respective attachment point. It would also be conceivable to arrange a tear seam or perforation between the second module-side attachment point 40 and the safety strap connection point 42. It would also be possible to completely replace the second safety strap 38 with a suitable decoupling device 44.

[0074] In the force path of the safety strap, from the second module-side attachment point 40 of the second safety strap 38 to the gasbag-side attachment point 33 of the first safety strap 32, the second module-side attachment point 40 of the second safety strap 38, the safety strap connection point 42, the first module-side attachment point 34 of the first safety strap 32, and the gasbag-side attachment point 33 of the first safety strap 32 are located one after the other. This means that a force F, which typically originates from the front wall 24 of the gasbag 12 and acts on the first safety strap 32, is transmitted into the vehicle via the first module-side attachment point 34 of the first safety strap 32 and the actuator unit 36, as long as the actuator unit 36 ​​is not activated. In this case, the decoupling device 44 is effectively bypassed.

[0075] Only when the actuator unit 36 ​​is activated and thus the first module-side attachment point 34 of the first retaining strap 32 hangs freely inside 30 of the gas bag 12, forces acting on the first retaining strap 32 are transmitted via the retaining strap connection point 42 to the second retaining strap 38 and thus to the decoupling device 44.

[0076] Inside 30 of the gas bag 12, a venting retaining strap 46 is also provided, which is connected to the venting device 28 and, on the module side, to the actuator unit 36. When the actuator unit 36 ​​is activated, the venting retaining strap 46 is always released. This causes the venting device 28 to open, allowing gas to escape from inside the gas bag 30.

[0077] The venting device 28 is implemented here by a vent opening 48 in the wall of the gas bag 12 and a flap 50 connected to the vent retaining strap 46 (see Fig. 4a). In the embodiments shown, the venting device 28 is designed such that the flap 50 closes the venting opening 48 as long as the venting catch strap 46 is under tension, and the flap 50 releases the venting opening and thus opens the venting device 28 when the venting catch strap 46 is released by the actuator unit 36.

[0078] If the actuator unit 36 ​​is not activated, the venting device 28 also remains closed. If the actuator unit 36 ​​is activated, the venting device 28 is always opened.

[0079] In order for the locking strap connection point 42, which connects the first locking strap 32 and the second locking strap 38, to be located in the locking strap path in front of the first module-side attachment point 34 of the first locking strap 32 on the actuator unit 36, the first locking strap 32 must extend at least a small distance beyond the first module-side attachment point 34.

[0080] In the examples shown here, the first retaining strap 32 is in each case designed to be long enough that its second end 52 extends beyond the retaining strap connection point 42 to the front wall 24 of the gas bag 12, where it is permanently fixed to the front wall 24 at a further gas bag-side attachment point 54. The first end 56 is attached to the gas bag-side attachment point 33 on the front wall 24.

[0081] The locking strap connection point 42 and the first module-side attachment point 34 are located between the ends 52, 56 and, in this example, approximately in the middle of the path of the first locking strap 32, so that the first locking strap 32 extends in a V-shape inside 30 of the gas bag 12 when the actuator unit 36 ​​is not activated and the gas bag 12 is filled. Therefore, when the actuator unit 36 ​​is not activated, a tensile force also acts on the section of the first locking strap 32 that runs between the first module-side attachment point 34 and the gas bag-side attachment point 54 on the front wall 24.

[0082] However, the second retaining strap 38 is longer than the length of the first retaining strap 32 between the retaining strap connection point 42 and the first module-side attachment point 34, and the second module-side attachment point 40 of the second retaining strap 38 is positioned on the module side in such a way that a load on the second retaining strap 38 is prevented when the actuator unit 36 ​​is not activated.

[0083] When the actuator unit 36 ​​is not activated, the ends 54, 56 of the first retaining strap 32, which are fixed to the front wall 24 of the gas bag 12, exert a tensile force on the front wall 24 and prevent the gas bag 12 from expanding to a volume exceeding a first volume V1 (see also Fig. 1 and Fig. 2 as well as Fig. 7 to 13).

[0084] Only when the actuator unit 36 ​​is activated and releases the first module-side attachment point 34 of the first retaining strap 32, and additionally triggers the decoupling device 44, can the first module-side attachment point 34 of the first retaining strap 32 move freely into the interior 30 of the gas bag 12 and thus no longer exert a tensile force on the front wall 24 of the gas bag 12. This then fills up to its second, larger volume V2 (see Fig. 3 as well as Fig. 14 to 16).

[0085] The Fig. 4 and Fig. Figure 5 shows the gasbag module 14 designed for mounting in the steering wheel 16. The only difference between the variants shown is that the decoupling device 44 is in Fig. 4 is formed by a tear seam at the second module-side attachment point 40 of the second retaining strap 38, while in Fig. 5 the decoupling device 44 is realized by a tear seam at the tether connection point 42.

[0086] The venting device 28 is arranged on an upper wall section of the gas bag 12 facing the windshield of the vehicle.

[0087] Fig. Figure 6 shows the gasbag module 14 designed for installation in the instrument panel 18. The operating principle is identical. The decoupling device 44 is the same as in the variants of the Fig. 4 and Fig. 5 trained (not shown in detail).

[0088] Here, the venting device 28 is arranged in a laterally directed wall section of the gas bag 12, so that the shape of the flap 50 is visible, which closes the venting opening 48 as long as the venting retaining strap 46 is fixed to the actuator unit 36.

[0089] In the Fig. 4, Fig. 5 and Fig. In case 6, the actuator unit 36 ​​is not triggered.

[0090] The Fig. Figures 7 to 16 show in greater detail the procedure for protecting a vehicle occupant by means of a vehicle occupant protection system 10 described above in the three different restraint situations.

[0091] The in the Fig. Figures 7 to 9 depict the first restraint situation and describe the behavior of the vehicle occupant protection system 10 in a restraint situation in which a large vehicle occupant 20 with a first body size K1 is sitting in the first, front seat position with a distance d1 to the gasbag module 14.

[0092] In this case, the gasbag 12 should be filled with the first, smaller volume V, but with sufficient hardness to catch a large vehicle occupant 20.

[0093] Fig. Figure 7 shows the gas bag 12 in the initial filling phase shortly after filling has begun. The actuator unit 36 ​​is not triggered, so both the first retaining strap 32 and the venting retaining strap 46 remain firmly attached to the actuator unit 36 ​​and thus fixed to the module.

[0094] Fig. Figure 8 shows the gasbag 12 in a middle phase during filling, where the gasbag 12 has already almost taken on its final shape.

[0095] Fig. Figure 9 shows the gas bag 12 fully filled with the first, smaller volume V1 after the final filling phase. The actuator unit 36 ​​is still not activated, so that even when fully filled, the front wall 24 is held at its desired distance from the gas bag module 14 by the intact first retaining strap 32, which is still fixed to the actuator unit 36 ​​at its first module-side attachment point 34. The venting retaining strap 46 is also still fixed to the actuator unit 36, so that the venting device 28 remains closed.

[0096] All forces acting on the first retaining strap 32 are transferred into the vehicle via the actuator unit 36 ​​and the first module-side attachment point 34 of the first retaining strap 32. Therefore, the decoupling device 44 always remains unloaded, so that it cannot trigger.

[0097] The Fig. Figures 10 to 13 show the behavior of the vehicle occupant protection system 10 in a second restraint situation, in which a smaller vehicle occupant 20 with a second body size K2 sits in the first, front seat position at a distance d1 while the restraint situation occurs.

[0098] Fig. Figure 10 shows an initial phase of filling the gas bag. Figure 12.

[0099] The actuator unit 36 ​​is not activated, so both the first retaining strap 32 and the venting retaining strap 46 remain fixed to the actuator unit 36. Since no force can act on the decoupling device 44, it does not trigger.

[0100] Fig. Figure 11 shows a middle phase of the filling of the gas bag 12, during which the front wall 24 moves towards the vehicle seat 22.

[0101] Fig. Figure 12 shows a final phase of filling, in which the front wall 24 has essentially come to rest and the gas bag 12 has essentially reached its first, smaller volume V1.

[0102] The dynamic forces that occurred while the front wall 24 moved outwards no longer act on the retaining strap 32, but only on the static forces caused by the internal pressure of the gas bag 12, whereby the internal pressure has already essentially reached its maximum value.

[0103] At this point, the actuator unit 36 ​​is activated and both the first retaining strap 32 at its first module-side attachment point 34 and the module-side end of the venting retaining strap 46 are released from the gas bag module.

[0104] Fig. Figure 13 shows the final state. Although the second retaining strap 38 and also the decoupling device 44 are now in the force flow between the gasbag-side attachment point 33 of the first retaining strap 32 and the second module-side attachment point 40 of the second retaining strap 38, the force acting on the decoupling device 44 remains below the specified force threshold and is insufficient to trigger it.

[0105] The force threshold at which the decoupling device 44 is triggered is generally selected such that purely static forces acting on the first retaining strap 32 after the gas bag 12 has been filled are insufficient to exceed the force threshold. Forces high enough to trigger the decoupling device 44 are only reached during the dynamic initial and intermediate filling phases, particularly during a rapid outward movement of the front wall 24. Therefore, if the actuator unit 36 ​​is activated in the final phase of filling the gas bag 12, when it has already essentially assumed its position in the vehicle interior and has essentially reached the first volume V1, the forces acting on the first retaining strap 32 are no longer sufficient to trigger the decoupling device 44.

[0106] As a result, the second retaining strap 38 remains attached to both the second module-side attachment point 40 and the retaining strap connection point 42, and the module-side attachment of the first retaining strap 32 is maintained via the second retaining strap 38.

[0107] The length of the second retaining strap 38 is chosen to be so short that the volume of the gas bag 12 achieved in this state still corresponds to the first volume V1 for all practical purposes.

[0108] In contrast to the first restraint situation described above, activating the actuator unit opens the venting device 28, as the venting retaining strap 46 is released on the module side. This allows gas to escape from inside 30 of the gas bag 12, enabling a softer landing for the smaller vehicle occupant 20.

[0109] The Fig. Figures 14 to 16 show the behavior of the vehicle occupant protection system 10 in a third restraint situation.

[0110] In this case, a vehicle occupant 20 of any height K1, K2 sits on the vehicle seat 22 in the second, rear seating position with a distance d2 to the gasbag module 14.

[0111] Fig. Figure 14 shows the vehicle occupant protection system 10 in the initial phase of filling the gas bag 12. Already in this phase, possibly already with activation of the gas generator of the gas bag module 14, the actuator unit 36 ​​is activated, so that the first module-side attachment point 34 of the first retaining strap 32 and the module-side attachment of the venting retaining strap 46 are released and detached from the gas bag module 14.

[0112] A point in time shortly after the activation of actuator unit 36 ​​is in Fig. Figure 15 shows that the decoupling device 44 is now located in the force flow between the front wall 24 of the gas bag 12, the first retaining strap 32, and the second module-side attachment point 40 of the second retaining strap 38. The forces occurring during the deployment of the gas bag 12, caused by the front wall 24 rapidly moving away from the gas bag module 14, act on the decoupling device 44 via the first retaining strap 32. These forces exceed the predetermined force threshold, causing the decoupling device 44 to trigger and the module-fixed connection of the first retaining strap 32 to be released.

[0113] As described above, this can be achieved, for example, by disconnecting the connection of the second safety strap 38 to the first safety strap 32 at the safety strap connection point 42, or by disconnecting the connection of the second safety strap to the gas bag module 14 at the second module-side attachment point 40. In the example shown here, the decoupling device 44 is provided at the safety strap connection point 42.

[0114] Fig. Figure 16 shows the final phase of the filling of the gas bag 12, in which the gas bag 12 reaches its fully filled state. Since neither the actuator unit 36 ​​nor the second retaining strap 38 holds the first retaining strap 32 in a module-fixed position on the gas bag module 14, the front wall 24 can move further towards the vehicle seat 22 than in the first two restraint situations. The gas bag 12 therefore fills up to its second, larger volume V2.

[0115] Both ends 52, 56 of the first retaining strap 32 remain firmly connected to the front wall 24 of the gas bag 12, but the retaining strap connection point 42 lies freely inside 30 of the gas bag 12.

[0116] Since the venting strap 46 has also been released by the actuator unit 36, the venting device 28 opens as in the second containment situation, so that the gas can escape from the interior 30 of the gas bag 12 and the gas bag 12 becomes softer.

[0117] For a gasbag module 14 arranged in the instrument panel 18, the three described restraint situations proceed analogously. The principle of the invention can, of course, also be implemented for gasbag modules 14 at other locations in any vehicle.

Claims

[1] Vehicle occupant protection system (10) comprising a gas bag module (14) comprising a gas bag (12) with a first and a second retaining strap (32, 38) extending inside the gas bag (12) and a module-mounted actuator unit (36), wherein the first retaining strap (32) is permanently attached to a gasbag-side attachment point (33) on a front wall (24) of the gasbag (12) and detachably fixed to the actuator unit (36) at a first module-side attachment point (34), and the second retaining strap (38) is attached to the module at a second module-side attachment point (40) and is connected to the first retaining strap (32) at a retaining strap connection point (42), wherein a decoupling device (44) is provided in the course of the second retaining strap (38) between the second module-side attachment point (40) and the retaining strap connection point (42), which triggers when a predetermined force threshold is exceeded, wherein activation of the actuator unit (36) releases the first retaining strap (32) on the module side and wherein the decoupling device (44) is only in the force flow between the second module-side attachment point (40) of the second retaining strap (38) and the gas bag-side attachment point (33) of the first retaining strap (32) when the actuator unit (36) is activated, characterized by , that a venting device (28) is provided, to which a venting retaining strap (46) running inside (30) the gas bag (12) engages, which is detachably connected to the actuator unit (36). [2] Vehicle occupant protection system (10) according to claim 1, characterized by, that in a safety strap run from the second module-side attachment point (40) of the second safety strap (38) via the safety strap connection point (42) and the first module-side attachment point (34) of the first safety strap (32) at the actuator unit (36) to the gas bag-side attachment point (33) of the first safety strap (32), viewed in the direction of the gas bag-side attachment point (33) of the first safety strap (32), the first module-side attachment point (34) of the first safety strap (32) is located after the safety strap connection point (42) and the second module-side attachment point (40) of the second safety strap (38). [3] Vehicle occupant protection system (10) according to any one of the preceding claims, characterized by, that the force threshold is chosen such that the first retaining strap (32) exerts a force (F) on the decoupling device (44) which is above the force threshold during an initial phase or a middle phase of the filling of the gas bag (12) when the actuator unit (36) is activated, while in a final phase of the filling a force (F) exerted by the first retaining strap (32) on the decoupling device (44) always remains below the force threshold. [4] Vehicle occupant protection system (10) according to any one of the preceding claims, characterized by , that the first retaining strap (32) is permanently attached to the gasbag-side attachment point (33) on the front wall (24) at a first end (56) and at a second end (52) on the gasbag wall, in particular on the front wall (24), and that the first module-side attachment point (34) and the retaining strap connection point (42) are located between the two ends (56, 52) of the first retaining strap (32). [5] Vehicle occupant protection system (10) according to any one of the preceding claims, characterized by , that the decoupling device (44) is arranged at the second module-side attachment point (40) of the second safety strap (38), the safety strap connection point (42) or in between. [6] Vehicle occupant protection system (10) according to any one of the preceding claims, characterized by , that the venting device (28) is designed such that the venting device (28) is only opened when the venting catch strap (46) is released by the actuator unit (36). [7] Vehicle occupant protection system (10) according to any one of the preceding claims, characterized by, that a vehicle seat (22) is provided which can assume a first and a second position, wherein the vehicle seat (22) in the second position is about 1.5 to 2 times further away from the gasbag module (14) than in the first position, and that the gasbag (12) in the first position of the vehicle seat (22) assumes a first, smaller volume (V1) when filled and in the second position of the vehicle seat (22) assumes a second, larger volume (V2) when filled. [8] Method for protecting a vehicle occupant (20) with a vehicle occupant protection system (10) according to one of the preceding claims, wherein a vehicle seat (22) is provided which can assume a first and a second position and which is designed to accommodate a vehicle occupant (20), wherein the vehicle seat (22) in the second position has a greater distance (d2) to a gasbag module (14) than in the first position, and wherein - in a restraint situation that occurs when the vehicle seat (22) is in the first position, a gas bag (12) of the gas bag module (14) is filled with a first, smaller volume (V1) and, depending on a size (K1, K2) of the vehicle occupant (20) on the vehicle seat (22), a venting device (28) of the gas bag (12) is open or closed, and - in a restraint situation that occurs when the vehicle seat (22) is in the second position, the gas bag (12) is filled with a second, larger volume (V2), and the venting device (28) is open. [9] Method according to claim 8 and with a vehicle occupant protection system (10) according to any one of claims 1 to 7, characterized by , that - in a restraint situation in which the vehicle seat (22) is in the first seating position, the actuator unit (36) is never activated or is only activated in a final phase of the inflation of the gas bag (12) and the decoupling device (44) is not triggered, and - in a restraint situation in which the vehicle seat (22) is in the second seating position, the actuator unit (36) is always activated and the decoupling device (44) is triggered. [10] Method according to claim 9, characterized by , that a venting device (28) is provided, to which a venting retaining strap (46) running inside (30) the gas bag (12) engages, which is detachably connected to the actuator unit (36), and that in the first seating position, depending on a first, larger and a second, smaller body size (K1, K2) of a vehicle occupant (20) on the vehicle seat (22) - the actuator unit (36) is activated in a final phase of filling the gas bag (12) when the vehicle occupant (20) has the second, smaller body size (K2) and - the actuator unit (36) is not activated if the vehicle occupant (20) has the first, larger body size (K1).

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