DE20012077U1 - Airbag module - Google Patents

Description

PRINZ & PARTNER GbR "

PATENT ATTORNEYS Manzingerweg 7

EUROPEAN PATENT ATTORNEYS D-81241 Munich

EUROPEANTRADEMARKATTORNEYS Tel. +49 89 89 69 80

200 12 077.8 08 May 2001

TRW Automotive Safety Systems
GmbH & Co. KG

Our reference: T 9386 DE A
KI/Hc

Gasbag module

The invention relates to a gas bag module, with a gas bag with a gas bag wall, which has a front wall facing the occupant to be restrained with a central section and a rear wall with an injection opening for connecting a gas generator, a fastening which

10 section when the gas bag is fully inflated so close to the inflation opening that the central section forms an indentation in the area of which the gas bag has a depth that is at least 40% less than the ring section immediately adjacent to the central section, and a module cover that allows the gas bag to exit in the event of restraint

15 is opened, wherein the module cover has an annular, predetermined exit opening which surrounds the fastening.

The invention particularly relates to a large-volume driver or passenger gas bag module that protects the head and upper body in the event of a frontal impact.

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The invention creates a module with a gas bag that is characterized by a lower load on the occupant that occurs when the occupant and the gas bag come into contact. In particular, if the occupant is "out of position", e.g. sitting too close to the steering wheel, the unfolding gas bag can hit the occupant and exert loads on him. In a conventional gas bag, the gas bag bulges out towards the occupant, so that the occupant can experience a reduced restraining effect from the gas bag if he is "out of position". Furthermore, the occupant can slip off the gas bag. Another disadvantage that is avoided by the invention is that the module usually has a gas bag cover to which a heavy emblem of the vehicle manufacturer is attached on the outside. When the module cover is suddenly swung open, it must be ensured that the emblem is held on the cover, which requires increased effort.

The gas bag module of the type mentioned at the beginning avoids the problems mentioned above and reduces the load exerted on the occupant by providing a fastening which holds the central section so close to the inflation opening when the gas bag is fully inflated that the central section forms an indentation in the area of which the gas bag has a depth that is at least 40 percent less than the ring section immediately adjacent to the central section. While in most of the gas bags to date the front wall always had no clear indentation, at most flattened areas caused by safety straps, the gas bag according to the gas bag module of the type mentioned at the beginning has a deep indentation, precisely in the central section, which is preferably contacted by the chin of a so-called 95 percent dummy when inflated. The strong indentation has provided advantages for passengers who are "out of position", especially for passengers who are sitting too close to the steering wheel. The fastening is designed in such a way that it prevents part of the central section from escaping from the gas bag module. The gas bag module has a module cover which, in the event of a restraint, allows the

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The gas bag is opened, with the module cover having a ring-shaped predetermined outlet opening. In previous gas bags, the outlet opening was always designed to be large in order to allow the gas bag to exit the module quickly. A ring-shaped outlet opening, on the other hand, offers the advantage that it only takes up a small area in the area of the cover and correspondingly small flaps have to be formed in the module cover. Small flaps, in turn, have the advantage that they pose a low risk potential when opened. The area of the module cover that lies inwards of the outlet opening, i.e. is surrounded by it, represents a retention area that forms the attachment of the central section. The retention area therefore has a dual function in that it serves on the one hand to retain the central section and on the other hand to attach the flaps to the module cover.

The object of the invention is to ensure easy production of a gas bag module with an annular gas bag, in particular to ensure good fastening of the center section.

This is achieved in a gas bag module of the type mentioned at the beginning by the module cover having a retaining area inwards, i.e. preferably radially inwards, of the outlet opening, on which an emblem is provided that is visible from the outside and designed as a separate part. The emblem attachment also forms the attachment of the central section. In the gas bag module according to the invention, the additionally provided, stable emblem, or more precisely its attachment, has a further function in that it prevents the central section from moving freely out of the module, so that a separate attachment for the central section is no longer necessary. In addition, the heavy emblem in the gas bag module according to the invention does not have to swing outwards, so that the emblem does not pose any danger, because the emblem is provided in the retaining area of the module cover, which does not swing outwards. This also means that the attachment of the swung-open flaps to the rest of the module cover is no longer as stable, because the

Flaps no longer have a heavy emblem and, as mentioned above, are of smaller dimensions than in the state of the art.

The restraint area is preferably attached to a bracket in the gas bag module,

e.g. attached to a cage surrounding the gas generator, which in turn is attached to the gas generator, to the module housing or e.g. to a gas generator holding plate, i.e. to a very stable part that is connected as directly as possible to the vehicle.

The indentation with the central section does not necessarily have to be a circular opening when viewed from the front wall. One design provides that when fully inflated, a slot-shaped opening is created when viewed from the front wall, i.e. a slot-shaped area is formed as a transition from the ring section of the front wall to the indentation. This means that the indentation closes increasingly from the attachment in the area of the cover to the ring section. This geometry when the gas bag is fully inflated can be achieved by a corresponding shape of the gas bag wall in the area of the indentation (also called the inner gas bag wall) and a corresponding cut of the adjacent, outer gas bag wall or the front wall. In addition, it is also possible for the indentation to be closed towards the front wall when fully inflated by the gas bag wall that borders the indentation pushing radially inwards until opposite sections of the gas bag wall abut against one another. In this case, the indentation becomes increasingly narrower from the attachment to the ring section and is finally closed.

The manufacture of the gas bag in the area of the deep indentation may be problematic. This indentation could, for example, consist of a piece of fabric sewn together to form a tube, but in this case the problem of attaching this piece of fabric to the rest of the front wall (ring section) then arises. One embodiment of the invention provides for simple manufacture of the gas bag provided in the gas bag module according to the invention.

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in that the indentation is delimited by an inner gas bag wall which consists of at least two wall parts. A front wall part, i.e. closer to the front, has a ring-shaped cut and is connected by its inner edge to the inner edge of the ring section of the front wall, the inner edge delimiting an opening to form the center section. A rear wall part, i.e. closer to the rear wall, is connected to the outer edge of the front wall part, preferably to its own outer edge. The fastening which prevents the center section from turning outwards engages the rear wall part in this embodiment. In this design, the gas bag looks like two gas bags nested one inside the other, in which the inner gas bag is inserted into the outer gas bag via the opening in the ring section. This embodiment is characterized on the one hand by simple production, in particular simple sewing of the wall parts. On the other hand, it has surprisingly been found that this gas bag offers better restraint values than a gas bag in which the central section is formed by a tube.

In summary, in the module according to the invention the gas bag is

The gas bag remains permanently attached directly to the module or close to the module, i.e. preferably to the module housing, in the central section. The gas bag is then ring-shaped and pushes outwards via a ring-shaped flap arrangement.

Further features and advantages of the invention will become apparent from the following description and from the following drawings, to which reference is made. In the drawings:

- Figure 1 is a cross-sectional view through a first embodiment of the gas bag module according to the invention,

- Figure 2 is a perspective view from above of the gas bag module according to the invention according to Figure 1,

- Figure 3 is an enlarged sectional view through a left lower half of the gas bag module in the area of the gas generator,

- Figure 4 is a cross-sectional view through a gas bag module according to a second embodiment, with the gas bag partially and completely deployed,

- Figure 5 is a plan view of the fully deployed gas bag shown in Figure 4,

- Figures 6 and 7 show two variants for the design of flaps forming a cover,

- Figure 8 is a schematic cross-sectional view through a gas bag module according to a further embodiment with the gas bag not yet fully inflated,

Figure 9 the gas bag module according to Figure 8 with fully inflated gas bag,

Figure 10 is a plan view of the front wall of the fully inflated gas bag in Figure 9,

- Figure 11 is a perspective view of the inner gas bag wall used in the gas bag module according to Figures 9 to 11,

Figure 12 a side view of a detail of the gas bag module with module cover and casing of the gas generator with a special variant of the connection of the module cover to the casing and

- Figure 13 is a cross-sectional view through the cover with integrated fastening, which can be used in a gas bag module according to the invention.

Figure 1 shows a gas bag module which is housed in the vehicle steering wheel or in the dashboard on the passenger side and serves to restrain the head and upper body. The module consists of a gas bag 3, a gas generator

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5, a module housing 7 in which the gas bag 3 and gas generator 5 are housed, and a module cover 9. The gas bag module according to Figure 1 is in particular a module housed in the steering wheel of a vehicle.

The gas bag 3 consists of a gas bag wall made of fabric material, with a front wall 11 that faces the occupant when the gas bag is inflated, as shown in Figure 1, and which the occupant contacts. A rear wall 12 is also provided, which can consist of a separate fabric part that has an inflation opening 21 through which the gas generator 5 is introduced into the gas bag 3. The front wall also has a so-called center section 13, which is defined by a deep indentation 27 and whose deepest region 16 is directly and permanently secured to the cover 9 or a casing (absorber pot) 33 of the gas generator 5 by a fastening. The fastening is an emblem 15 with a molded-on screw 17, which is screwed to the outside of the cover 9 or the casing 33, which has the shape of a cage.

The cover 9 has a ring around the center section

adjacent opening flaps 19, which are pivoted upwards when the gas bag unfolds (see Figure 3). In the opened state, an annular, preferably circular outlet opening 14 is then released in the cover 9.

The fastening in the form of the emblem provides the indentation and keeps the center section, in particular the area 16 of the center section closest to the gas generator 5, close to the gas bag module. A ring section 23, which surrounds the center section 13 and forms the remaining part of the front wall 11, is at a greater distance from the cover 9, so that the gas bag has a much greater depth than in the area of the center section 13, whereby in the embodiment shown the gas bag has no depth at all in the middle, because it remains in its original position in the part of the center section 13 immediately below the emblem 15, which it also has in

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folded state and does not move at all towards the occupant in this area.

Inwards of the ring section 23, the indentation 27 is formed in the center of the front wall, which, as tests have shown, has a positive effect on the restraining effect. Because the center section 13 of the gas bag is prevented from exiting the module, only the ring section 23 can contribute to opening the flaps 19, whereby the force generated during inflation is directed primarily radially outwards, so that the gas bag unfolds mainly radially at the beginning of its unfolding process and the movement in the direction of the occupant is small. In the middle area of the center section, no movement at all in the direction of the occupant is possible, so that the stress on the occupant by the gas bag 3 is reduced. In previous gas bags, the center section, which moves quickly outwards, is the part of the gas bag wall that represents the greatest stress for the occupant when the occupant and the gas bag wall come into contact with each other.

Figure 3 shows the clamping of the gas bag 3 in the area of the blow-in opening 21. The gas bag is clamped to the flange 35 of the gas generator 5 by the pot-shaped casing 33 of the gas generator. 37 designates the so-called retaining area of the cover 9, which lies inward of the annular outlet opening 14 and which, together with the emblem 15, forms the fastening of the central section 13. In the embodiment shown, the opening flaps 19 are formed on the inner circumference of the annular outlet opening 14.

In the embodiment shown in Figure 4, the cage-shaped holder 33, which surrounds the gas generator 5, as well as the fastening of the central section 13 via the emblem 15 to the casing 33 can be seen again. The front wall 11 consists of an annular fabric section, which is connected at its outer edge to the rear wall 12 via a seam 41. At the inner edge of the ring section 23, which limits the opening in the ring section 23 and also defines the central section 13, the ring section is provided with

the inner edge of a front wall part 43 having a ring-shaped cut. A corresponding circumferential seam is designated 45. The front wall part 43 is followed by a rear wall part 47, which is connected at its outer edge to the outer edge of the front wall part 43 via a circumferential seam 49. The rear wall part 47 is the area that is also attached to the casing 33 in the area of its center. The wall parts 43, 47 form an inner gas bag wall. In the fully unfolded state, which is shown with broken lines, the abrupt, deep indentation 27, which is delimited by the front and rear wall parts 43, 47, is clearly visible.

By cutting it into a circle (wall part 47) or a ring (wall part 43), folds are formed in the area of the indentation 27 when fully inflated, which is symbolized by the zigzag line that delimits the indentation 27 in Figure 5. However, this irregular folding is likely to be advantageous in terms of the restraining effect, because the gas bag formed in this way achieves better restraining effects than a gas bag in which the indentation 27 is formed by a cylinder made of fabric material that does not have any folds when inflated, since the folds narrow the cross-section and increase the stability of the inflated air bag.

Figures 6 and 7 show two variants for the design of the opening flaps 19. According to Figure 6, all flaps 19 are formed on the outer circumference of the outlet opening 14. In the variant shown in Figure 7, mutually associated flaps 19 are provided on the inner and outer circumference of the outlet opening 14. The opposing flaps 19 each cover approximately half of the radial extent of the annular outlet opening. This variant has the advantage that the flaps 19 have a shorter overall length compared to the flaps shown in Figures 3 and 6. Thus, each individual flap has a comparatively low kinetic energy when opened and also does not protrude so far into the passenger compartment, so that the

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The risk of injury to the vehicle occupant is reduced by the flaps 19 in the event of a possible secondary impact.

In the embodiment according to Figure 8, it can be seen that the indentation 27 runs from the deepest region 16, i.e. the part of the front wall that does not leave the gas bag module when it is inflated, to the ring section 23 and is completely or almost completely closed, so that no or only a small opening can be seen from the outside, which forms the transition from the ring section to the central section 13 and thus to the indentation 27.

Figure 9 shows the fully deployed gas bag, which has an almost closed shape towards the vehicle occupant.

In Figure 10 it can be seen that the ring section 23 extends around a slot 71 which has a small thickness d. The ring section 23 has an elliptical shape which is formed by the fact that the ring section 23 is already elliptical in the cut and has an area with the slot 71. The slot 71 must be large enough that when the cover is torn open it can slide along the emblem 15 and the part of the cover which is located directly below the emblem 15 and can move out of the gas bag module.

The cut of the gas bag wall and the individual wall parts can also be selected so that when the gas bag is fully inflated, the slot 71 is closed, i.e., opposite sections 73, 75 come to rest on one another and close the indentation to form the ring section. The thickness d is therefore 0.

In Figure 11, the inner gas bag wall consisting of two wall parts 43, 47 according to Figure 4 can be seen when the gas bag is fully inflated, whereby the slot 71 can also be seen, which forms the transition from the ring section 23 to the center section 13.

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The assembly of the gas bag module must be carried out in such a way that, on the one hand, the part of the central section 13 held on the cover 9 is actually prevented from exiting the gas bag module. On the other hand, it must be ensured that the entire adjacent part of the gas bag wall can exit the gas bag module and the cover. It must therefore be prevented that other parts of the gas bag wall besides the central part of the central section are clamped by the fastening of the retained part of the central section.

In Figure 12 it can be seen that the cover 9 has on its inside a molded projection 77 in the form of a cylinder which protrudes on the inside and has the same outer diameter as a bulge 79 formed on the upper end wall of the casing 33. The projection 77 and the bulge 79 lie against one another and clamp between them the part of the center section of the gas bag which is prevented from exiting the gas bag module. Symbolically visible is a screw 81 molded onto the emblem 15 which projects through the slot 71 and is fixed on the inside of the casing 33 with a nut 83. The area of the gas bag wall which forms the edge of the slot 71 runs around the emblem 15 and around the projection 77. It can also lie radially outside the inner edge 85 of the outlet opening 14, whereby this can also be achieved by a correspondingly large projection 77. Another possibility is that, for example, the projection 77 in the lower area has the shape of the later slot 71 and widens outwards towards the emblem 15, so that the gas bag widens in the area of the slot 71 like a buttonhole when exiting the module and then, after exiting, narrows again to the slot 71.

Figure 13 shows a gas bag retaining plate 91 embedded in the cover 9 with two integrally formed threaded pins 93 which form the fastening for the central section 13, in that the threaded pins 93, similar to Figure 12, protrude through the front wall of the casing 33.

Yet another embodiment provides that the emblem 15 is designed as a separate part and is connected to a gas bag retaining plate 9Γ provided outside the cover 9 according to Figure 8 or merges into it in one piece.

Two methods are envisaged for equipping the gas bag module with the gas bag. The first method provides that the cover 9 is designed as a pot-shaped cap into which the gas bag is folded, whereby it must be ensured during this folding that, based on Figure 12, only the part of the gas bag wall to be held back may rest against the front wall of the projection 77. The remaining part of the center section then rests against the surface of the projection 19. When inserting the gas bag, a so-called dummy serves as a replacement for the casing 33. After inserting the gas bag, the dummy is replaced by the casing 33 and the nut 83 is screwed on. Another embodiment provides that the gas bag module consists of two pot-shaped parts, a pot-shaped cap forming the cover 9 and a pot-shaped receiving part. The casing 33 is placed in the receiving part so that an annular space is formed between the peripheral wall of the receiving part and the casing 33, into which the gas bag is folded from above. After the gas bag has been inserted, the cover 9 is placed on top and screwed on from below, for example.

Claims (22)

1. Gasbag module, with
a gas bag ( 3 ) with a gas bag wall which has a front wall ( 11 ) facing the occupant to be restrained with a central section ( 13 ) and a rear wall ( 12 ) with an injection opening ( 21 ) for connecting a gas generator ( 5 ),
a fastening ( 15 ) which holds the central section ( 13 ) in the fully inflated state of the gas bag ( 3 ) so close to the inflation opening that the central section ( 13 ) forms an indentation ( 27 ) in the region of which the gas bag has a depth which is at least 40 percent less than the ring section ( 23 ) immediately adjacent to the central section ( 13 ),
and a module cover ( 9 ) which is opened in the case of retention to allow the gas bag ( 3 ) to exit, the module cover ( 9 ) having an annular, predetermined exit opening ( 14 ) which surrounds the fastening, characterized in that the module cover ( 9 ) has a retention area ( 37 ) inwardly of the exit opening ( 14 ) and the module cover ( 9 ) has an emblem ( 15 ) in the retention area ( 37 ) which is visible from the outside and is designed as a separate part and
that the emblem fastening simultaneously forms the fastening of the central section ( 13 ). 2. Gas bag module according to claim 1, characterized in that the retaining region ( 37 ) forms at least part of the fastening of the center section ( 13 ). 3. Gas bag module according to claim 2, characterized in that the retaining region ( 37 ) is fastened to a holder in the gas bag module. 4. Gas bag module according to claim 3, characterized in that the holder is a cage-like casing ( 33 ) surrounding the gas generator. 5. Gas bag module according to claim 4, characterized in that the holder is attached to the rear of the gas generator ( 5 ) or to the module housing ( 7 ). 6. Gas bag module according to one of the preceding claims, characterized in that the annular outlet opening ( 14 ) is closed by adjacent flaps ( 19 ) which are integrally formed on the module cover ( 9 ). 7. Gas bag module according to claim 6, characterized in that the flaps ( 19 ) are formed on the inner circumference of the annular outlet opening ( 14 ). 8. Gas bag module according to claim 6, characterized in that the flaps ( 19 ) are formed on the outer circumference of the annular outlet opening ( 14 ). 9. Gas bag module according to claim 6, characterized in that opposing flaps ( 19 ) are formed on the inner circumference and on the outer circumference of the annular outlet opening ( 14 ). 10. Gas bag module according to one of the preceding claims, characterized in that the fastening is designed such that it prevents a part of the central section ( 13 ) of the gas bag ( 3 ) from exiting the gas bag module. 11. Gas bag module according to claim 10, characterized in that the fastening comprises a gas bag holding plate ( 91 ; 91 ') provided outside the gas bag ( 3 ). 12. Gas bag module according to claim 11, characterized in that the gas bag holding plate ( 91 ) is embedded in the cover ( 9 ). 13. Gas bag module according to claim 11 or 12, characterized in that the emblem ( 15 ) designed as a separate part is connected to the gas bag holding plate ( 91 ; 91 '). 14. Gas bag module according to one of the preceding claims, characterized in that the ring section ( 23 ) of the front wall ( 11 ) merges into the central section ( 13 ) via a slot-shaped region when the gas bag ( 3 ) is fully inflated. 15. Gas bag module according to claim 14, characterized in that the gas bag ( 3 ) is folded such that the slot-shaped region runs around the fastening in the folded state. 16. Gas bag module according to claim 15, characterized in that the gas bag ( 3 ) is folded such that the slot-shaped region in the folded state lies radially inward of a gas bag holding plate as part of the fastening. 17. Gas bag module according to one of claims 14 to 16, characterized in that the ring section of the front wall ( 11 ) has an elliptical outer edge. 18. Gas bag module according to one of the preceding claims, characterized in that the indentation ( 27 ) in the fully inflated state is closed by adjacent opposite sections ( 83 , 85 ) of the gas bag wall towards the ring section ( 23 ) of the front wall. 19. Airbag module according to one of the preceding claims, characterized in that the indentation ( 27 ) is delimited by an inner airbag wall which consists of at least two wall parts, wherein a front wall part ( 43 ) has an annular cut and is connected with its inner edge to the inner edge of the ring section of the front wall ( 11 ), wherein the inner edge delimits an opening for forming the center section ( 13 ), wherein a rear wall part ( 47 ) is connected to the outer edge of the front wall part ( 43 ) and wherein the fastening of the center section ( 13 ) engages the rear wall part ( 47 ). 20. Gas bag module according to claim 19, characterized in that the front wall ( 11 ) and rear wall ( 12 ) consist of two annular wall parts which are connected to one another at the outer circumference. 21. Gas bag module according to claim 19 or 20, characterized in that the wall parts are sewn together. 22. Gas bag module according to one of the preceding claims, characterized in that the emblem serves as a holder for the retaining region ( 37 ).