DE102023120543A1 - vehicle occupant restraint system - Google Patents

Abstract

A vehicle occupant restraint system has a gas bag (12) whose outer wall (25) which is curved in the inflated state is formed at least for the most part by at least one inflatable mat (16, 18) which is fixed to the vehicle at an inflation section (34). The inflatable mat (16, 18) has a front side (28) which delimits the gas bag (12) to the outside and an opposite rear side (26) which delimits an inner cavity (24) in the gas bag interior. When the gas bag (12) is fully inflated, an impact surface (30) for an associated vehicle occupant (32) is formed on the front side (28).

Description

The invention relates to a vehicle occupant restraint system with a gas bag.

For an optimal restraint effect, the vehicle occupant should hit the gas bag after as short a displacement path as possible in a restraint situation. However, many gas bags are installed in structures fixed to the vehicle, such as the steering wheel, the instrument panel or the roof frame. The gas bags therefore sometimes have to have a large filling volume so that their impact surface can be positioned close to the occupant. This requires a large amount of filling gas and is therefore costly.

The object of the invention is to reduce the required filling gas volume for a gas bag and thus to make the vehicle occupant restraint system more cost-effective.

This object is achieved by a vehicle occupant restraint system with a gas bag, the outer wall of which, when inflated, is curved and is formed at least for the most part by at least one inflatable mat, which is fixed to the vehicle at an inflation section. The mat has a front side that delimits the gas bag on the outside and an opposite rear side that delimits an inner cavity in the gas bag interior. When the gas bag is fully inflated, an impact surface for an associated vehicle occupant is formed on the front side.

Instead of providing a single-layer outer wall for the gas bag, which encloses an interior like a balloon that is completely filled with gas, the gas bag now has an inflatable outer shell, so to speak, while the inside of the gas bag remains filled with air. This reduces the filling volume by a large part of the inside of the gas bag, although a large total volume is enclosed by the gas bag. The inside of the gas bag here therefore refers to the air-filled cavity, not a pressurized gas-filled interior of the inflatable mat between its front and back.

This also means that the amount of filling gas to be provided can be reduced, which means that a smaller gas generator can be installed, for example, thus saving weight, costs and installation space.

The gas bag derives most of its inherent rigidity from the inflatable mat.

The inflatable mat is preferably double-walled, with the space between the front and back being inflated with pressurized filling gas.

Preferably, the front and back of the mat are made of a known gas bag fabric.

In general, the mat is elongated and flat, so that the distance between the front and back, i.e. the thickness of the mat, is significantly smaller than the length and width of the mat. The distance between the front and back of the mat when fully inflated is preferably between 1 cm and 15 cm. The length can be between 100 cm and 200 cm, for example.

For example, the front and back of the mat are approximately parallel when inflated, so that the thickness of the mat is approximately the same along its length.

For example, the techniques known from curtain-like side gas bags can be used to manufacture the mat, in particular one-piece weaving (OPW gas bag). It is of course also possible to connect the front and back of the mat not only at their edges, but also on their surface in certain zones in order to increase stability and/or to adjust the distance between the front and back of the mat.

Any suitable technique can be used here to ensure that a given thickness of the mat, i.e. a given distance between the front and back of the mat, is achieved. For example, there can be single-layer zones, connecting threads that run from one wall of the mat to the other through the interior of the mat, woven domes and/or cylinder chambers.

If necessary, predefined curvature or bending zones can also be specified. For example, it would be conceivable to manufacture the mat with a predetermined basic curvature in order to achieve the curvature of the outer wall at least partially through the inherent shape of the inflatable mat.

The curvature of the inflatable mat, which forms the curved outer wall of the gas bag, is preferably uniform and is not achieved by just one or a few kinks, so that the outer wall of the gas bag has as few edges as possible.

The internal pressure of the inflatable mat when fully inflated can be approximately be chosen like the internal pressure of a known curtain-like side gas bag.

The front of the inflatable mat defines the outer contour of the gas bag when fully inflated.

The front of the inflatable mat may be positioned facing largely outwards into the vehicle interior when the gas bag is fully inflated, while the rear is at least partially facing into the internal cavity enclosed by the mat.

Preferably, the inflatable sections of the gas bag consist exclusively of one or more inflatable mats; additional inflatable chambers have proven to be unnecessary.

Such gas bags can be used in all suitable places in the vehicle. The gas bag can be fixed to an instrument panel, for example, and thus form a front gas bag, in particular a passenger gas bag. The gas bag can also be fixed to a vehicle seat and form protection for the occupant on this or an adjacent vehicle seat. For example, it is possible to fix the gas bag in the backrest of a vehicle seat so that it unfolds in front of a vehicle occupant sitting behind this seat, for example on a back seat, and can protect them. It is also possible to fix the gas bag in a roof area of the vehicle, from which it extends downwards into the vehicle interior when inflated in order to catch a vehicle occupant in a lateral or forward movement. Such a gas bag can therefore be used both in the front area of a vehicle and on the back seats of a vehicle or in rows of seats behind one another, such as in a coach. If the gas bag is fixed in the roof area, it can be moved from the side walls of the vehicle into the interior in the transverse direction of the vehicle in order to unfold and inflate in the longitudinal direction of the vehicle in front of a vehicle occupant and to catch him in a forward movement. It is also conceivable that the gas bag be arranged on other vehicle components, for example consoles or folding tables.

To fix the gas bag to a component fixed to the vehicle, an inflation section of the gas bag can be used, for example, through which it is filled with filling gas.

To protect a vehicle occupant on a vehicle seat, the front of the inflatable mat can be curved around an imaginary axis that lies transversely in front of the vehicle seat. If the occupant is to be protected from being displaced forward in the longitudinal direction of the vehicle, this axis should extend in the transverse direction of the vehicle. In any case, the gas bag is preferably aligned in the inflated state so that its impact surface faces the vehicle occupant on the vehicle seat.

In a preferred variant, the cavity is completely enclosed circumferentially by at least one mat. This results in an outer wall of the gas bag that is closed in a circumferential direction around an axis of the cavity.

It is possible to roll up a single mat and fix it to itself so that an enclosed cavity is formed. It is also possible to connect two mats at their long ends to form an enclosed cavity.

There may also be several mats, each shaped into a hollow space, so that the gas bag has several hollow spaces in total. It may also be that a single mat is rolled up in such a way that several hollow spaces are formed.

However, the cavities are always filled with air rather than with filling gas.

Each cavity can be open on at least one side so that air can flow in and out of the cavity at the sides. In one possible variant, the cavity is open on both sides.

It is also possible to close the cavity laterally on at least one side, preferably on both sides, using a non-inflatable flexible layer to reduce the movement of air in the cavity. The non-inflatable flexible layer is preferably fixed to one edge of the mat. For example, the non-inflatable flexible layer is a fabric layer that is folded together with the gas bag before the gas bag is deployed. When the vehicle occupant hits the impact surface, the non-inflatable flexible layer can retain some of the air in the cavity and thus increase the rigidity and dimensional stability of the gas bag.

The non-inflatable flexible layer may be designed to be aspirating so that it draws air into the cavity when the gas bag unfolds and inflates. This can be achieved, for example, by a membrane function of the non-inflatable flexible layer or by valves.

To give the gas bag the desired shape and the inflatable mat the desired curvature To give the mat a certain degree of flexibility, at least one safety strap can be attached to the mat, which holds the mat in a predetermined curved state. The safety strap runs through the hollow space.

The gas bag can also be designed to be depth-adaptive by providing at least two safety straps of different lengths, of which the shorter can be released depending on the situation. Under certain conditions, the gas bag can have a first, smaller depth and under other conditions a second, larger depth, which determines the distance from the gas bag's attachment to the vehicle-mounted structure that the impact surface of the inflated gas bag is located. Possible parameters for situation dependency include, for example, the position of the vehicle seat of the assigned vehicle occupant, the position of the occupant, their size and their weight.

The shorter safety strap can be released by suitable known means, for example a release or separation mechanism in the area of the blowing section.

The filling volume of the gas bag and the internal pressure in the inflatable mat(s) remain basically the same, regardless of whether a safety strap is released or not. This means that there is no need to adjust the filling gas quantity or control the internal pressure, as is conventionally used.

In one possible variant, an inflatable mat forms at least one circumferentially closed roll when the gas bag is fully inflated, with the inflatable mat being permanently and firmly attached to itself in the circumferential direction to close the at least one roll. The roll surrounds the hollow space or one of the hollow spaces inside the gas bag. This increases the stability of the gas bag, with the roll either having the impact surface or supporting another area of the gas bag where the impact surface is formed. The attachment can be made, for example, at one end of the mat or on one surface of the mat.

In another possible variant, the gas bag comprises two inflatable mats that are permanently attached to one another. If necessary, the gas bag could also comprise more than two inflatable mats. The two inflatable mats can be manufactured as completely separate mats, so that each of them has its own inflation section. In this case, the inflation sections are preferably fixed to the vehicle in close proximity to one another and can optionally be connected to a single gas generator or to two separate gas generators. Alternatively, it is also possible to provide a common inflation section, with the two mats merging into one another in one piece at one end, where the inflation section is then arranged. In any case, both inflatable mats are always inflated.

The two mats are preferably permanently attached to each other at their ends that are not fixed to the vehicle structure. In this case, both mats together enclose a single cavity inside the gas bag.

If one or more safety straps are provided, they are preferably attached to the joint fastening of the ends of the inflatable mats. The tension exerted by the safety strap pulls the ends into the cavity inside the gas bag, resulting in a roughly heart-shaped cross-section.

In another possible variant, one of the inflatable mats is rolled up and permanently attached to itself and additionally permanently attached to the other inflatable mat away from its end, so that the gas bag has two cavities.

If one or more safety straps are provided, in this variant they are preferably fixed to the attachment of the longitudinal end of one of the inflatable mats to the surface of the other inflatable mat.

In a further variant, at least one inflatable mat is rolled up into a circumferentially closed roll and permanently attached to itself when the gas bag is fully inflated, with the two inflatable mats additionally being permanently attached to one another on the surface of at least one mat. It is possible to fix the end of the non-rolled up inflatable mat to the surface of the rolled up inflatable mat.

In another variant, both mats are rolled up into a roll and attached to themselves, while the two rolls are additionally connected to each other on the surface of the inflatable mats. In this case, the two mats are attached to each other at their front sides.

For example, a passenger airbag arranged on the instrument panel can comprise exactly two inflatable mats which are connected at their ends, whereby the ends of the inflatable mats are fixed to the instrument panel via a possibly adaptive safety strap so that a tensile stress is built up.

For a passenger airbag, it is also possible to roll up the upper of the two inflatable mats and fix the second mat to the surface of the first mat.

For a gas bag that unfolds from the roof area and is intended, for example, for vehicle occupants in rear seats, the variant that is suitable is one in which there are two inflatable mats, each rolled up into a roll, with the two mats fixed to each other on their surface. The impact surface is formed on one of the mats, while the second mat can rest on the first mat.

For vehicle occupants in the rear seats, a gas bag is suitable which comprises only a single inflatable mat and which is attached to the backrest of the seat in front of the respective vehicle occupant, with the inflatable mat rolled up into a roll and attached to itself in order to stabilize the gas bag.

Of course, all other suitable variants with one or more inflatable mats that are fixed to themselves and to other inflatable mats at any point can also be used for various purposes.

The fastening can be done via seams, adhesives or welds, for example.

Forming a gas bag from one or more inflatable mats, so that the gas bag is essentially defined by an inflatable outer wall and one or more air-filled inner cavities, allows a large-area and large-volume gas bag to be provided with a small volume of filling gas. Since the inflatable mats can take on a variety of shapes due to their curvature and the way the mats are attached to themselves and to each other, gas bags can be easily created for a wide variety of purposes.

• - 1 eine schematische Darstellung eines erfindungsgemäßen Fahrzeuginsassen-Rückhaltesystems mit einem vollständig aufgeblasenen Gassack, der an einer Instrumententafel angeordnet ist, in einer Schnittansicht gemäß einer ersten Variante in einer ersten kleineren Tiefe;
• - 2 das Fahrzeuginsassen-Rückhaltesystem aus 1, mit dem Gassack in einer zweiten, größeren Tiefe;
• - 3 eine schematische Darstellung eines erfindungsgemäßen Fahrzeuginsassen-Rückhaltesystems mit einem vollständig aufgeblasenen Gassack in einer Schnittansicht gemäß einer zweiten Variante, in der ersten Tiefe;
• - 4 das Fahrzeuginsassen-Rückhaltesystem aus 3 beim Auffangen des Fahrzeuginsassen;
• - 5 das Fahrzeuginsassen-Rückhaltesystem aus 3, wobei der Gassack eine zweite Tiefe angenommen hat;
• - 6 eine Variante des Gassacks, bei der der Hohlraum seitlich durch eine nicht aufblasbare, flexible Lage verschlossen ist;
• - 7 eine schematische Darstellung eines erfindungsgemäßen Fahrzeuginsassen-Rückhaltesystems mit einem vollständig aufgeblasenen Gassack gemäß einer dritten Variante in einer Schnittansicht, wobei der Gassack an der Rückenlehne eines Fahrzeugsitzes angeordnet ist, vor dem Auffangen des Fahrzeuginsassen, für einen ersten Abstand des Fahrzeuginsassen;
• - 8 das Fahrzeuginsassen-Rückhaltesystem aus 7 während des Auffangens des Fahrzeuginsassen;
• - 9 das Fahrzeuginsassen-Rückhaltesystems aus 7 vor dem Auffangen des Fahrzeuginsassen, für einen zweiten Abstand des Fahrzeuginsassen;
• - 10 das Fahrzeuginsassen-Rückhaltesystem aus 9 während des Auffangens des Fahrzeuginsassen;
• - 11 eine schematische Darstellung eines Fahrzeuginsassen-Rückhaltesystems mit einem in einem Dachbereich angeordneten Gassack, vor der Entfaltung des Gassacks;
• - 12 das Fahrzeuginsassen-Rückhaltesystem aus 11 mit vollständig befülltem Gassack in einer Schnittansicht, in einer vierten Variante, vor dem Auffangen eines Fahrzeuginsassen; und
• - 13 das Fahrzeuginsassen-Rückhaltesystem aus 11 während des Auffangens des Fahrzeuginsassen.

The invention is described in more detail below using several embodiments with reference to the attached figures. In the figures:

• - 1 a schematic representation of a vehicle occupant restraint system according to the invention with a fully inflated gas bag arranged on an instrument panel, in a sectional view according to a first variant at a first smaller depth;
• - 2 the vehicle occupant restraint system 1 , with the gas bag at a second, greater depth;
• - 3 a schematic representation of a vehicle occupant restraint system according to the invention with a fully inflated gas bag in a sectional view according to a second variant, in the first depth;
• - 4 the vehicle occupant restraint system 3 when catching the vehicle occupant;
• - 5 the vehicle occupant restraint system 3 , whereby the gas bag has assumed a second depth;
• - 6 a variant of the gas bag in which the cavity is closed at the sides by a non-inflatable, flexible layer;
• - 7 a schematic representation of a vehicle occupant restraint system according to the invention with a fully inflated gas bag according to a third variant in a sectional view, wherein the gas bag is arranged on the backrest of a vehicle seat, before catching the vehicle occupant, for a first distance of the vehicle occupant;
• - 8 the vehicle occupant restraint system 7 while catching the vehicle occupant;
• - 9 the vehicle occupant restraint system 7 before catching the vehicle occupant, for a second distance of the vehicle occupant;
• - 10 the vehicle occupant restraint system 9 while catching the vehicle occupant;
• - 11 a schematic representation of a vehicle occupant restraint system with a gas bag arranged in a roof area, before the gas bag is deployed;
• - 12 the vehicle occupant restraint system 11 with fully inflated gas bag in a sectional view, in a fourth variant, before catching a vehicle occupant; and
• - 13 the vehicle occupant restraint system 11 while catching the vehicle occupant.

For reasons of clarity, not all identical components are always provided with reference symbols. Identical reference symbols designate identical or essentially identical components and parts.

The 1 and 2 show a vehicle occupant restraint system 10 with a gas bag 12 according to a first variant, which is attached to a vehicle fixed structure, in this case to an instrument panel 14, and is also held there in the folded state before a restraint situation.

The gas bag 12 has exactly two mats 16, 18 which are inflatable with pressurized filling gas and which form the only inflatable chambers of the gas bag 12.

The two inflatable mats 16, 18 are firmly and permanently connected to one another at their longitudinal ends 20, 22, which lie in the vehicle interior when inflated. In this way, an air-filled inner cavity 24 is completely enclosed circumferentially with respect to an axis A by the two inflatable mats 16, 18.

The inflatable mats 16, 18 form a compressed gas-filled outer wall 25 of the gas bag 12, which defines the outer contour of the gas bag 12, while the air-filled cavity 24 represents the gas bag interior, which in conventional gas bags is filled with filling gas.

The side of the inflatable mat 16, 18 which faces into the cavity 24 is referred to here as the rear side 26, while the opposite side facing into the vehicle interior is referred to as the front side 28.

At the 1 In the inflated state of the gas bag 12, the upper inflatable mat 16, which is higher along a vehicle vertical direction H than the other inflatable mat 18, has a baffle surface 30 on the front side 28 for catching a vehicle occupant 32 (see, for example, 3 and 4 ) trained.

Each of the inflatable mats 16, 18 has a longitudinal extension between an inflation section 34, which is fixed to the vehicle-fixed structure, and its longitudinal end 20, 22, which is significantly longer than a thickness d between the front side 28 and the rear side 26. The thickness d is also significantly smaller than the diameter of the cavity 24.

In the gas bag 12, only the inflatable mats 16, 18 are inflated with pressurized filling gas, which enters the inflatable mats 16, 18 through the blowing section 34 and which, in the restraint situation, is supplied by a suitable pressurized gas source, for example one or more gas generators 36 (indicated in 1 ) is provided.

The cavity 24, on the other hand, is filled with ambient air under the normal air pressure prevailing in the vehicle interior.

For example, the inflatable mats 16, 18 are each elongated and flat unless forced into a curve by external forces and are manufactured as a separate component before being formed into the gas bag 12.

Each of the inflatable mats 16, 18 has one or more inflatable chambers in its interior between the front 28 and the back 26.

In this example, the inflatable mats 16, 18 are manufactured in a one-piece weaving process as an OPW gas bag, with the outer edges including the longitudinal ends 20, 22 of the inflatable mats 16, 18 each being woven in a single layer, with this one layer on the surface of the inflatable mat 16, 18 being divided into the front 28 and the back 26. For example, non-inflatable areas are provided on the surface of the inflatable mat 16, 18, in which the front 28 and the back 26 are brought together again into a single layer in order to set the thickness d of the inflatable mats 16, 18 to the desired value (not shown). Inside the inflatable mats 16, 18, optional mat-internal structures 38 are provided to limit the thickness d. These are in 1 indicated, whereby in the inflatable mat 16, weaving threads are shown as examples, which connect the front 28 and the back 26 within the inflatable mat 16 and which run in a zigzag or X-shape between the front 28 and the back 26. In the inflatable mat 18, arched or dome-shaped structures are indicated as examples, which also connect the front 28 and the back 26 at certain points and thus specify the thickness d. In addition, the mat-internal structures 38 ensure greater dimensional stability of the inflatable mats 16, 18.

The high internal pressure and, if applicable, the mat-internal structures 38 ensure that the inflated gas bag 12 is stiff enough to catch a vehicle occupant 32 striking the impact surface 30 and to sufficiently dissipate the kinetic energy of the occupant. The hollow space 24 is deformed, but the two inflatable mats 16, 18 are not separated from one another.

In addition, the gas bag 12 is supported on a windshield 40 of the vehicle, in this case with the upper inflatable mat 16, which leads to additional stiffening and stabilization.

In the example shown here, an adaptive safety strap structure with a first, shorter safety strap 42 and a arranged parallel to it, a second, longer retaining strap 44. Both retaining straps 42, 44 are attached at one end in the area of the inflation section 34 and at their opposite end to the inflatable mats 16, 18, here to the fixation of the longitudinal ends 20, 22. The retaining straps 42, 44 are both chosen to be so short that they contribute to the shape of the gas bag 12 through their tensile force and hold the inflatable mats 16, 18 in a predetermined curved shape.

When the gas bag 12 is fully inflated, the retaining straps 42, 44 limit a depth t ₁ , t ₂ of the gas bag 12, by which the latter extends from its inflation section 34 to its impact surface 30 into the vehicle interior.

In addition, the depth of the gas bag 12 can be adjusted to a first, smaller depth t ₁ and a second, larger depth t ₂ via the safety straps 42, 44 of the adaptive safety strap structure (see 1 and 2 ).

Depending on certain recorded parameters, the shorter safety strap 42 either remains the only tension-transmitting means in the gas bag 12 in a restraint situation, or it is released, so that the second safety strap 44 takes over the task of the tension-transmitting means in the gas bag 12. In other words, if the first safety strap 42 remains intact and fixed, the gas bag 12 can only expand to its smaller depth t ₁ , which is defined by the length of the first safety strap 42. If, however, it is released or destroyed, the gas bag 12 expands to its greater depth t ₂ , which is predetermined by the length of the second safety strap 44.

The specified parameters include, for example, a distance of a vehicle seat 46 (see, for example, 7 ) to the gas bag 12, size or weight of the vehicle occupant 32 as well as his current seating position, or parameters which relate to the force acting on the vehicle in the current restraint situation, and can be adjusted as desired at the discretion of the expert.

The decision to release the first safety strap 42 is made by a control unit (not shown). The release mechanism can be designed as desired, for example an explosive bolt or a mechanical release device in the area of the blowing section 34.

In any case, the second retaining strap 44 remains firmly attached so that the maximum depth of the gas bag 12 is the depth t ₂ .

The difference in length between the depth t ₁ and the depth t ₂ can, for example, be approximately 200 mm.

It would also be conceivable to provide only a single safety strap and to leave it permanently fixed or to make it detachable.

In the 1 and 2 In the variant shown, the gas bag 12 is a front gas bag, more precisely a passenger gas bag, so that the depth t ₁ , t ₂ of the gas bag 12 designates a longitudinal extension of the gas bag 12 along a vehicle longitudinal direction L, while the axis A runs in the vehicle transverse direction Q.

The 3 and 4 show a variant of the gas bag 12 just described.

The only difference from the first variant is that the two inflatable mats 16, 18 are not connected at their longitudinal ends 20, 22 and enclose a single cavity 24, but one of the inflatable mats 16, 18, here the upper inflatable mat 16, is rolled up into a roll 47 closed in the circumferential direction U around the axis A.

In order to form the roll 47, the longitudinal end 20 of the inflatable mat 16 is firmly and permanently fixed to its rear side 26. The roll 47 formed by the inflatable mat 16 further increases the stability of the gas bag 12.

The other inflatable mat, here the lower inflatable mat 18, is firmly and permanently fixed with its longitudinal end 22 on the surface of the front side 28 of the inflatable mat 16.

Thus, the gas bag 12 has a total of two air-filled cavities 24, 48.

The impact surface 30 is formed here as in the first variant on the upper inflatable mat 16.

4 shows a restraint situation in which the vehicle occupant 32 is caught by the gas bag 12. The inflatable mat 16 is stiffened by the roller 47 and its evasive options are minimized. This is indicated by the arrows P ₁ . The lower inflatable mat 18 is supported on the instrument panel 14 (see arrows P ₂ ) and thus forms a support for the upper inflatable mat 16.

The 3 and 4 show a restraint situation in which the gas bag 12 only assumes the first, smaller depth t ₁ and thus both retaining straps 42, 44 remain fixed.

5 shows a restraint situation in which the shorter retaining strap 42 is released, while the longer retaining strap 44 remains fixed, so that the gas bag 12 assumes its second, greater depth t ₂ .

The fastenings of the inflatable mats 16, 18 to one another are not loosened in the process. The fastening point of the longitudinal end 22 of the inflatable mat 18 on the front side 28 of the inflatable mat 16 is selected such that the gas bag 12 can stretch as a whole in order to assume the greater depth t ₂ .

In the variants shown so far, the cavities 24, 48 were open at the sides so that air can flow in and out unhindered.

6 shows a variant in which the cavity 24 (or the cavities 24, 48, if the gas bag 12 has several cavities) are closed laterally by a non-inflatable, flexible layer 50. In this example, such a non-inflatable, flexible layer 50 is arranged on both sides of the cavity 24, but it would also be conceivable to do this on only one side.

The non-inflatable, flexible layer 50 is designed in such a way that air flows into the cavity 24 during inflation of the gas bag 12, thus enabling an aspiration effect. This is achieved, for example, by suitable flaps, valves or the material of the non-inflatable, flexible layer 50.

A fabric or a membrane, for example, can be used as a material for the non-inflatable, flexible layer 50.

For example, the non-inflatable, flexible layer 50 is fixed at its peripheral edge 51 to a peripheral edge 52 (indicated by dashed lines) of the inflatable mats 16, 18.

If the vehicle occupant 32 is caught, the non-inflatable, flexible layer 50 delays the outflow of air from the cavity 24 and thus increases the rigidity and resistance that the gas bag 12 offers to the impact of the vehicle occupant 32.

The 7 to 10 show a further variant in which the gas bag 12 comprises only a single inflatable mat 16.

As already described above, the inflatable mat 16 is rolled up into a roll 47 which is circumferentially closed around the axis A, wherein the longitudinal end 20 of the inflatable mat 16 is firmly and permanently fixed on the surface of the back 26 of the mat 16.

In the example shown here, the gas bag 12 is attached to the backrest of a vehicle seat 53 and is also held there in the folded state, with the vehicle seat 53 being arranged in the longitudinal direction L in front of the vehicle seat 46 on which the vehicle occupant 32 to be restrained is sitting. The vehicle seat 46 is, for example, the back seat of a car or a rear row of seats in a larger vehicle, such as a bus or a train.

The gas bag 12 unfolds from the backrest of the vehicle seat 53 such that the axis A lies transversely in front of the vehicle seat 46 and the vehicle occupant 32. As a result, the impact surface 30 of the gas bag 12 on the front side 28 of the inflatable mat 16 faces the vehicle occupant 32.

Due to its flexibility, the gas bag 12 is suitable for different seat distances d ₁ , d ₂ or different seat back inclinations without further adjustment, in particular without safety straps.

7 and 8 show a restraint situation for a larger distance d ₁ , while 9 and 10 represent a restraint situation for a smaller distance d ₂ .

The gas bag 12 unfolds close to the vehicle occupant 32, so that the latter may come into contact with the impact surface 30 before it is displaced or only after a very short forward displacement. Since the roll 47 formed by the inflatable mat 16 is easier to deform than a completely filled gas bag with the same outer contours, the gas bag 12 can deform sufficiently to prevent excessive force from being applied to the vehicle occupant 32 even when the distances between the vehicle occupant 32 and the impact surface 30 are different. The gas bag 12 deforms upwards here, i.e. along the vertical direction H of the vehicle, in order to compensate for the smaller distance.

As in all other variants, the filling quantity of the gas bag 12 with pressurized filling gas is not changed depending on the distance d ₁ , d ₂ .

In the 11 to 13 a further variant is shown. In this case, the gas bag 12 is accommodated in a gas bag module 54 before it is deployed, which is mounted in a roof area 56 of the vehicle. The gas bag module 54 is arranged such that it lies in the transverse direction Q of the vehicle in front of a vehicle seat 46 with the vehicle occupant 32 to be restrained.

In a restraint situation, the gas bag 12 unfolds downwards from the roof area 56 and comes to rest in front of the vehicle occupant 32 (see 12 ).

In this variant, the two inflatable mats 16, 18 are each rolled up into a circumferentially closed roll 47, which is arranged transversely to the vehicle occupant 32.

The longitudinal end 20 of the inflatable mat 16 is firmly and permanently attached to the back 26 of the inflatable mat 16, while the longitudinal end 22 of the inflatable mat 18 is firmly and permanently attached to the back 26 of the inflatable mat 18. Each of the two inflatable mats 16, 18 encloses a hollow space 48.

In addition, the two inflatable mats 16, 18 are firmly and permanently connected to one another on their surface at a further fastening point 58. In this case, their front sides 28 are fixed to one another in the area of the rollers. This encloses a further hollow space 24 between the two inflatable mats 16, 18, so that the gas bag 12 has a total of three hollow spaces 24, 48.

The gas bag 12 is aligned such that the two rollers 47 point away from the vehicle occupant 32 and the front side 28 with the impact surface 30 formed thereon faces the vehicle occupant 32 as a continuous surface. The vehicle occupant 32 therefore does not come into contact with the depression in the gas bag 12 formed by the rollers 47.

If the vehicle occupant 32 hits the gas bag 12, as 13 shows, the inflatable mat 16, on which the impact surface 30 is formed, rests with its roller 47 on the roller 47 of the second inflatable mat 18, which in turn is pressed against the roof area 56. In this way, the gas bag 12 is further stabilized and can easily absorb the forces exerted by the vehicle occupant 32.

All features of the individual embodiments and variants can be freely exchanged or combined with one another at the discretion of the person skilled in the art. In particular, all of the gas bags 12 described can also be used in any vehicle at locations other than those shown. Each of the variants shown can also be provided with a non-inflatable, flexible layer 50 on one or both sides.

In order to optimally align the impact surface 30 with the vehicle occupant 32, the imaginary axis A is arranged transversely to the vehicle seat 46 of the vehicle occupant 32 to be restrained.

The inflatable mats 16, 18 can form separate inflatable chambers, which are also prefabricated separately. Both inflatable mats 16, 18 have in particular the same shape and the same filling volume. In this case, each of the inflatable mats 16, 18 has its own blowing section 34, which are connected to a compressed gas source in close proximity to one another (see 1 to 5 ). It is also possible to assign a separate pressure gas source to each inflatable mat 16, 18. In this example, the internal pressure generated is the same in both inflatable mats 16, 18.

Alternatively, it is also possible to manufacture the two inflatable mats 16, 18 in one piece and to arrange a single blowing section 34 in the middle of their longitudinal extension, via which both inflatable mats 16, 18 are filled (see 12 and 13 ). In this case too, in the example shown here, the internal pressure generated in both inflatable mats 16, 18 is the same.

Regardless of the option for the inflatable mats 16, 18 shown in the individual variants, separate inflatable mats 16, 18 or integrally connected inflatable mats 16, 18 can be used.

All gas bags 12 shown in the figures are shown in their fully inflated state.

In general, it is not intended that fastenings which connect an inflatable mat 16, 18 to itself or to another inflatable mat 18, 16 are released during the restraint situation.

Claims (11)

Vehicle occupant restraint system with a gas bag (12), the outer wall (25) of which, when inflated, is curved and is at least largely formed by at least one inflatable mat (16, 18) which is fixed to the vehicle at an inflation section (34), wherein the inflatable mat (16, 18) has a front side (28) which delimits the gas bag (12) to the outside and an opposite rear side (26) which delimits an inner cavity (24, 48) in the gas bag interior, and wherein, when the gas bag (12) is fully inflated, an impact surface (30) for an associated vehicle occupant (32) is formed on the front side (28). Vehicle occupant restraint system according to claim 1 , wherein the gas bag (12) is attached to an instrument element panel (14), a vehicle seat (53) or a roof area (56) of the vehicle. Vehicle occupant restraint system according to one of the preceding claims, wherein the front side (28) of the inflatable mat (16, 18) is curved about an imaginary axis (A) lying transversely in front of a vehicle seat (46). Vehicle occupant restraint system according to one of the preceding claims, wherein the cavity (24, 48) is completely enclosed circumferentially by at least one inflatable mat (16, 18). Vehicle occupant restraint system according to one of the preceding claims, wherein the cavity (24, 48) is laterally open on at least one side. Vehicle occupant restraint system according to one of the preceding claims, wherein the cavity (24, 48) is laterally closed on at least one side by a non-inflatable flexible layer (50). Vehicle occupant restraint system according to one of the preceding claims, wherein at least one retaining strap (42, 44) is fixed to the inflatable mat (16, 18), which holds the inflatable mat (16, 18) in a predetermined curved state and in particular two retaining straps (42, 44) with different lengths are provided, of which the shorter one can be released depending on the situation. Vehicle occupant restraint system according to one of the preceding claims, wherein an inflatable mat (16, 18) forms at least one circumferentially closed roll (47) in the fully inflated state of the gas bag (12), wherein the inflatable mat (16, 18) is firmly and permanently fastened to itself in the circumferential direction (U) for closing the at least one roll (47). Vehicle occupant restraint system according to one of the preceding claims, wherein the gas bag (12) comprises two inflatable mats (16, 18) which are permanently attached to one another. Vehicle occupant restraint system according to claim 9 , wherein the two inflatable mats (16, 18) are permanently attached to one another at their longitudinal ends (20, 22) or one of the inflatable mats (16, 18) is rolled up and permanently attached to itself and is additionally permanently attached to the other inflatable mat (18, 16) away from its longitudinal end (20, 22), so that the gas bag (12) has two cavities (24, 48). Vehicle occupant restraint system according to claim 9 , wherein at least one inflatable mat (16, 18) is rolled up into a circumferentially closed roll (47) and permanently fastened to itself in the fully inflated state of the gas bag (12), and the two inflatable mats (16, 18) are additionally permanently fastened to one another on the surface of at least one inflatable mat (16, 18).

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