DE102005037300A1 - Gas bag for driver air bag module in motor vehicle, has fixing areas fixed at inner side of gas bag, and catch arm with trapezoid shaped section, by which no traction forces are transmitted when unfolding gas bag - Google Patents

Abstract

The gas bag has a catch strap for limiting the expansion of a unfold gas bag along a limiting direction, during filling of the bag with gas. The catch strap consists of a catch arm (7b) extended in a limitation direction, where the traction force acts on the catch arm during unfolding of the gas bag. Fixing areas are connected by the catch arm. The fixing areas are fixed at the inner side of the gas bag. The catch arm has a discharging area, by which no traction forces are transmitted when unfolding the gas bag, where the discharging area is designed as a trapezoid shaped section (8). An independent claim is also included for an air bag module for a motor vehicle with a gas bag.

Description

The The invention relates to a gas bag for a motor vehicle according to the preamble of claim 1.

One Such airbag has at least one inner side, the one with Gas fillable Interior of the airbag faces, as well as a flat trained Tether for limiting an expansion of the deploying airbag along a boundary direction. This will be unfolding of the gas bag in the gas bag introduced gas through a gas generator provided, the one required for inflating the airbag gas quantity releases. The limiting strap has over a Fangarm interconnected mounting areas on each other spaced at the inside of the airbag are fixed, so that the tentacle absorbs tensile forces when unfolding the airbag.

From the DE 43 15 142 C3 is such a gas bag for a motor vehicle is known, with a along a limiting direction extending tentacle of a tether, the tentacle having two free ends, each integrally connected to two attachment areas, by means of which the tether is fixed to opposite inner sides of the airbag. The attachment areas are in this case attached by means of a seam to the respective inner side of the airbag.

At the Unfolding the airbag, the tentacle along the boundary direction put under tension, as the two opposite each other Insides that over the tentacle are connected together when unfolding the airbag diverge in the limiting direction until the tentacle Completely is extended along the boundary direction and another divergence the two inner sides prevented. This proves to be disadvantageous that over the Transfer tentacles to the seams Traction forces, with the tentacle above the attachment areas with the opposite inner sides of the Airbag is connected, the seam holes of the seams greatly widen what is in the Extreme case leads to cracks in the gas bag.

Of the The invention is therefore based on the problem of providing an airbag, in which a stress on a connection between tether and Inside of the airbag reduced by the tensile forces acting on the deployment is.

This Problem is solved by a gas bag with the features of the claim 1 solved.

After that has the tentacle of the tether on a discharge area, through through which no tensile forces transmitted during deployment of the airbag can be.

This solve that inventive problem advantageous manner, since due to the discharge area along the the tentacle in the limiting direction transmitted tensile forces not on a relief region in the limiting direction opposite Area of a connection between the mounting area and the Concentrated inside the airbag, but transverse to the boundary direction and spaced from that area are introduced into the gas bag. In such a region of a connection between the attachment area the tether and the inside of the airbag, it may, for example act around a section of a seam, by means of which the attachment area is attached to the inside of the airbag.

Prefers the relief area is adjacent to one of the attachment areas arranged, wherein preferably the discharge area to one of Attachment areas adjacent. This prevents the tensile forces in the limiting direction between the unloading area and the fixing area transversely to the limiting direction, so that they are not predominantly at a single area of the connection between tether and inside of the gas bag are introduced into the gas bag.

In a preferred embodiment of Invention is the one attachment area on an inside of a Part of the airbag attached, whose the interior of the airbag opposite outside an impact surface for one Vehicle occupants forms. This may be the gas bag, for example for a gas bag for a driver airbag module acting in a steering wheel of the motor vehicle is arranged.

Of the Relief area is preferably flat and continue preferably formed by a section of the tentacle. The tentacle can So for example, as well as the gas bag itself from a textile surface tissue be prepared with a relief area formed by a cutout.

It is conceivable here, a cut edge that surrounds the cutout, additionally to seal or secure with a circumferential seam.

In an alternative embodiment According to the invention, the relief region is shaped in such a way that, in the deployed state of the gas bag, it is not under a tension which is caused by the tensile forces transmitted along the catching arm. In this case, the relief region preferably has a bulge perpendicular to the limiting direction and is preferably connected to the tentacle by means of a seam. Such a relief region may thus be, for example, a cutout in the tentacle which is covered with a flexible sheet, the sheet having a bulge such that no tensile forces can be transmitted through the sheet-metal arch. It is of course also conceivable to form such a bulging relief region integrally with the tentacle or alternatively to connect via a bond or a weld with the tentacle.

In A preferred variant of the invention is the discharge area arranged perpendicular to the limiting direction centered on the tentacle. As a result, the relief region are transverse to the direction of limitation flanking portions of the tentacle substantially of the same Width (perpendicular to the direction of limitation) and therefore point at Unfolding the airbag, that is, with respect to the transmission of tensile forces, a similar behavior.

Prefers is the quotient of a largest width of the catching arm perpendicular to the limiting direction (counter of Quotients) and a maximum width of the unloading area (denominator of the quotient) perpendicular to the limiting direction amount greater than three. In this way, a major stress of the connection between the attachment area and the inside of the airbag at an area that is the relief area in the limiting direction opposite, avoided, while at the same time the discharge area vertically to the limiting direction flanking areas of the tentacle one have sufficient width, so that the stability of the tentacle through the relief area, for example in the form of a cutout in the tentacle, not diminished.

The Width of the relief region preferably increases perpendicularly Boundary direction in the limiting direction (to which a mounting area towards). This ensures that the tensile forces in the limiting direction on both sides along the discharge area, in one Direction perpendicular to the boundary direction spaced apart be introduced into the attachment region of the tether.

In a preferred embodiment the tentacle is essentially Y-shaped trained and accordingly has two free legs, the depart from a main thigh. The relief area is preferred in this case of an edge of the attachment area and the two free Thighs, each over a free end are connected to that edge, framed.

In Another variant of the invention is the discharge area circular educated. Alternative to the Y-shaped shaping the tentacle of the tentacle is further preferably formed rectangular. D. h., The tentacle, for example, from a rectangular strip a flexible sheet, for example, a fabric to be made. The attachment areas can in one piece be formed on the tentacle, d. h., that from the tentacle and the existing tether may be considered as a single, one-piece Cut available. The discharge area can here as a Cutout be formed, which punched or cut into the tentacle becomes. Furthermore, it is conceivable that the rectangular tether unfolded in Condition of the airbag perpendicular to the limiting direction has a curvature and therefore, for example, as a part of a lateral surface of a Cylinder is formed (the cylinder axis coincides with the limiting direction together). Furthermore, a rectangular tentacle course, as well with not circular Relief areas, for example a trapezoidal relief area, be combined.

Prefers is the one attachment area in the deployed state of the airbag essentially complete on the inside of the part of the airbag, whose interior the outside of the airbag an impact surface for one Vehicle occupants forms. For this purpose, the attachment area, for example with a peripheral region surrounding the attachment area on the inside be set of the airbag. Such a connection can be considered one Adhesive joint, a welded joint or also a seam may be formed. It may be appropriate a spacing between this connection and an edge of the Provide mounting area, so that the mounting area has a free edge area that is not directly connected to the inside is. Such a free edge area is in particular for binding a tentacle to the attachment area suitable.

Preferably the fastening area is circular, wherein preferred the tentacle in the deployed state of the airbag from a peripheral area of the attachment region projects along the boundary direction. This is advantageous because in this way the attachment area is particularly easy, namely one piece can be formed on the tentacle.

In a particularly preferred variant of the invention falls the Boundary direction with a main deployment direction of the airbag along which the airbag along unfolds in the direction one to be protected Person stretches.

Prefers the relief area lies in the limiting direction of an area a connection between the attachment region of the tether and the inside of the airbag opposite, the unfolding of the Airbag exposed to the greatest tensile forces is. Such a region of a connection may be, for example to act on a section of a seam that has at least one seam hole the seam comprises, by means of which the attachment area on the inside of the airbag is fixed, wherein the seam hole under a Zugkraftbeaufschlagung to the detriment of the stability of the airbag expand or even tear down can. This is due to the inventive arrangement of the discharge area prevented.

One Another idea of the invention is the provision of an airbag module for a Motor vehicle with a gas bag according to the invention. It can do this For example, an airbag module for a steering wheel of a motor vehicle act. The airbag module can also with appropriate design of the airbag and possibly other components elsewhere be activated in or on the motor vehicle to protect a person.

The illustrated features and advantages of the invention are based on the following descriptions of figures of embodiments be clarified.

It demonstrate:

1 a schematic, partially sectioned view of a gas bag according to the invention with a tether,

2 a schematic, partially sectioned view of a modification of the in the 1 shown airbag,

3 a schematic, perspective view of a gas bag, in the 2 kind shown,

4 a further schematic perspective view of a gas bag in the 2 and 3 kind shown,

5 a schematic representation of the functional dependence of prevailing at a region of a connection between a tether and an inside of a gas bag tension (ordinate) and the location (abscissa) of the area along that compound (prior art), and

6 a schematic representation of the functional dependence between the prevailing at a region of a connection between a tether and an inside of a gas bag tension (ordinate) and the location (abscissa) of the area along that compound in a gas bag according to the invention.

1 shows a schematic section of an airbag module 1 for mounting in a steering wheel of a motor vehicle with a trough-shaped module carrier 2 , which is open in the direction of the z-axis, which is oriented parallel to the steering axis of the steering wheel. The cutting plane is parallel to the z-axis and lies in the plane of the paper. The module carrier 2 is characterized by a perpendicular to the steering axis oriented, flat shaped bottom 3 as well as through a side wall 3a formed at right angles from the ground 3 protrudes in the direction of the z-axis. The module carrier 2 thus forms a receptacle for a gas generator 4 on the inside facing a driver 3b of the soil 3 of the module carrier 2 is fixed and for inflating a gas bag 5 serves on the inside 3b of the soil 3 with an inlet opening of the airbag 5 bordering edge region of the airbag 5 over a gas bag clamping 6 is fixed. This protrudes the gas generator 4 in the direction of the z-axis in the inflow opening of the airbag 5 into it.

In the 1 is the gas bag 5 shown in a deployed state. The gas bag 5 extends here starting from the inside 3b of the soil 3 in a Hauptentfaltungsrichtung, which is parallel to the z-axis (ie parallel to the steering axis), from the trough-shaped module carrier 2 out, with the gas bag 5 in a direction perpendicular to the main deployment direction oriented plane has a greater spatial extent, as in the main deployment direction. The gas bag 5 is in the deployed state according to 1 further formed cylindrically symmetrical to the main deployment direction.

Adjacent to the gas generator 4 and to the inflow opening of the airbag 5 is at one of the bottom 3 facing away from inside 5a of the gas bag 5 an Indian 1 Not shown, parallel to the plane of extension of the soil 3 (ie perpendicular to the plane of the paper) extending mounting portion of a tether 7 fixed, of which a flat, rectangular tentacle 7b of the tether 7 protrudes in a direction parallel to the z-axis, coinciding with the steering axis limiting direction B. The tentacle 7b extends ent long of the limiting direction B to one of the inside 5a opposite inside 5b of the gas bag 5 at the tentacle 7b over a flat fastening area 7c is set, which is substantially parallel to the ground 3 extends (that is perpendicular to the paper plane) and on the inside 5b of the gas bag 5 is applied.

The tentacle 7b serves to limit the expansion of the airbag 5 in the limiting direction B. In the folded state of the airbag 5 this is initially completely in an interior of the trough-shaped module carrier 2 arranged, with that interior through the module carrier 2 and one on the side wall 4 fixed cover A is formed. When unfolding the airbag 5 by inflating the airbag 5 by means of the gas generator 4 tears the cover A along a tear line and the gas bag 5 unfolds from the interior into the airbag module 1 surrounding outdoor space. In this case, the two in the direction of boundary B opposite inner sides 5a and 5b of the gas bag 5 in boundary direction B only to the extent far from each other until the tentacle 7b is fully extended in the direction B and due to the gas pressure in the gas bag 5 Due to the filling with gas prevails, which receives parallel to the limiting direction B along the tentacle pulling forces.

Due to the restriction of the expansion of the gas bag 5 in the limiting direction B by the rectangular tether 7 , is the load of a connection between tether 7 and the inside 3b of the soil 3 facing inside 5b of the gas bag 5 particularly high in an area where the over the tentacle 7b transmitted tensile forces in the inside 5b of the gas bag 5 be initiated.

With a deployed airbag 5 who like in the 1 shown, having a symmetrical to the steering axis cross-section, wherein the tentacle 7b is also arranged symmetrically to the steering axis along the steering axis (in the limiting direction B), the area of the connection between the inside 5b of the gas bag 5 and the attachment area 7c of the tether 7 which is particularly loaded by a tension S generated by tensile forces, located at a location M along that connection which is transverse to the limiting direction B at the center of the tentacle 7b is localized.

5 shows the qualitative course of the voltage S (ordinate) along the perpendicular to the limiting direction B extending connection between the mounting area 7c and the gas bag 5 in a known tether without discharge area.

To minimize the stress on the area of the connection between the attachment area 7c and the inside 5b of the airbag at location M, hereinafter referred to as the connection area at location M, by the voltage S, is at the in the 1 illustrated tentacle 7b a relief area in the form of a circular section 8th formed, which is the maximum loaded connection area at location M in the limiting direction B opposite and transverse to the limiting direction B centrally and adjacent to the mounting area 7c on the tentacle 7b is trained.

Through the neckline 8th of the tentacle 7b can not pull along the tentacle 7b in the limiting direction B through the cutout 8th through to the inside 5b of the gas bag 5 be transmitted so that the stress caused by tensile forces of the connection area is reduced at location M. This is achieved because in the absence of the excerpt 8th on the connection area at location M concentrated tensile forces in the presence of such a cutout 8th perpendicular to the boundary direction B on both sides of the connection area at the location M in spaced from each other at the locations M and M '' located areas of the connection between the tether 7 and the inside 5b of the gas bag 5 to be initiated, hereinafter referred to as connection areas at the locations M 'and M ", so that in an ideal case the stresses S acting at the locations M' and M 'are opposite those at the connection area at the location M (in the absence of the detail 8th ) prevailing voltage S are halved.

The qualitative profile of the stress S (ordinate) along the perpendicular to the fastening direction B extending connection between the mounting area 7c and the inside 5b of the gas bag 5 at a tether 7 with discharge area 8th , is in the 6 shown schematically. Here, the selected locations M, M 'and M''of the individual connection areas are marked on the abscissa.

An advantageous reduction of the stress S acting on the connection region at the location M while at the same time providing sufficient tear strength of the tentacle arm 7b , is given when the ratio of the width D of the tentacle 7b transverse to the limiting direction B to the width D 'of the section 8th across the boundary direction B amount is greater than three.

2 shows in connection with 3 and 4 a modification of the in the 1 described catch strap 7 , In contrast to 1 is the tether 7 of the 2 not rectangular but Y-shaped. The tentacle 7b is formed here by a boundary direction B he stretched main thighs 9 , from the symmetrical to the steering axis two free legs 10 depart, which diverge at an acute angle and over their two free ends with a circular, flat mounting area 7c connected to the inside 3b of the soil 3 opposite inside 5b of the gas bag 5 by means of one along an edge of the attachment area 7c running double seam is set. In the 2 extends the circular attachment area 7c substantially perpendicular to the paper plane and parallel to the ground 3 , wherein in the inflated state of the airbag 5 the Y-shaped tentacle 7b from the attachment area 7c towards the inside 5b opposite inside 5a of the gas bag 5 protrudes and in the unfolded state of the airbag 5 along the boundary direction B to this inside 5a extends.

In contrast to 1 is in the 2 the relief area as a trapezoidal cutout 8th formed by the two free thighs 10 Y-shaped tentacle 7b and to the free ends of the free legs 10 subsequent attachment area 7c is framed.

Also with a trapezoidal cut-out 8th for minimizing the stress S acting on the joint area at the location M, the cutout 8th in the limiting direction B, the quotient of the maximum width D of the tentacle 7b perpendicular to the boundary direction B and the largest width D 'of the trapezoidal cutout 8th perpendicular to the limiting direction B in terms of magnitude preferably greater than three.

In the in the 1 to 4 shown gas bag 5 it is an airbag 5 for a driver airbag module 1 , With appropriate design of the individual elements of the airbag 5 , in particular the tether 7 can the gas bag 5 but also inflated elsewhere in or on a motor vehicle to protect a person and by means of the tether 7 be limited in its spatial extent.

1

airbag module

2

module carrier

3

ground

3a

Side wall

3b

inside

4

inflator

5

airbag

5a

inside

5b

inside

6

Gassackklemmung

7

tether

7b

tentacle

7c

fastening area

8th

neckline

9

main leg

10

suitor leg

Z

z-axis

B

limiting direction

A

cover

M

place

M '

place

M ''

place

D

width

D '

width

S

tension

Claims (24)

Airbag for a motor vehicle with - an inside of the airbag, which faces a gas-filled interior of the airbag, and - a flattened tether for limiting an expansion of the gas bag unfolding during filling gas along a limiting direction, which extends in the limiting direction a tentacle has, on the deployed during deployment of the airbag tensile forces, and on the tentacle interconnected mounting areas, which are mutually spaced fixed to the inside of the airbag, characterized in that the tentacle ( 7b ) a discharge area ( 8th ), through which upon deployment of the airbag ( 5 ) no tensile forces are transmitted. Airbag according to claim 1, characterized in that the discharge area ( 8th ) adjacent to one of the attachment areas ( 7c ) is arranged. Airbag according to claim 2, characterized in that the discharge area at the one attachment area ( 7c ) adjoins. Airbag according to claim 2 or 3, characterized in that the one attachment area ( 7c ) on an inside ( 5b ) of a part of the airbag ( 5 ) is set, which faces away from the interior outside forms an impact surface for a vehicle occupant. Airbag according to one of the preceding claims, characterized in that the discharge area ( 8th ) is formed flat. Airbag according to one of the preceding claims, characterized in that the discharge area ( 8th ) through a section of the tentacle ( 7b ) is formed. Airbag according to one of claims 1 to 5, characterized in that the relief area ( 8th ) is formed such that it in the unfolded state of the airbag ( 5 ) is not under a tension caused by the tensile forces. Airbag according to claim 7, characterized in that the discharge area ( 8th ) has a bulge perpendicular to the limiting direction (B). Airbag according to claim 7 or 8, characterized in that the discharge area ( 8th ) by means of a seam with the tentacle ( 7b ) connected is. Airbag according to one of the preceding claims, characterized in that the discharge area ( 8th ) perpendicular to the limiting direction (B) in the middle of the tentacle ( 7b ) is trained. Airbag according to one of the preceding claims, characterized in that the ratio of a maximum width (D) of the tentacle ( 7b ) perpendicular to the limiting direction (B) to a maximum width (D ') of the relief region ( 8th ) perpendicular to the limiting direction (B) is greater in magnitude than three. Airbag according to claim 4 and one of claims 5 to 11, characterized in that the width of the discharge area ( 8th ) perpendicular to the limiting direction (B) in the limiting direction (B) to the one attachment area ( 7c ) increases. Airbag according to claim 11 or 12, characterized in that the discharge area ( 8th ) has the shape of a trapezoid, with two parallel, perpendicular to the limiting direction (B) oriented, different lengths sides. Airbag according to claim 12 or 13, characterized in that the tentacle ( 7b ) is substantially Y-shaped, with two free legs ( 10 ), by a main thigh 9 depart. Airbag according to claim 4 and claim 14, characterized in that the discharge area ( 8th ) of the two free thighs ( 10 ), which each have a free end to the one attachment area ( 7c ), is framed. Airbag according to claim 11, characterized in that the discharge area ( 8th ) is circular. Airbag according to one of claims 1 to 13 or claim 16, characterized in that the tentacle ( 7b ) is rectangular. Airbag according to claim 4 and one of claims 5 to 17, characterized in that the one fastening area ( 7c ) in the unfolded state of the airbag ( 5 ) substantially completely on the inside of the airbag ( 5 ) is present. Airbag according to claim 18, characterized in that the fastening area ( 7c ) is circular. Airbag according to claim 18 or 19, characterized in that the tentacle ( 7b ) in the unfolded state of the airbag ( 5 ) from an edge region of the attachment area ( 7c ) protrudes in the limiting direction (B). Airbag according to one of the preceding claims, characterized in that the limiting direction (B) with a main deployment direction of the airbag ( 5 ) along which the gas bag ( 5 ) unfolds. Airbag according to one of the preceding claims, characterized in that the discharge area ( 8th ) in the limiting direction (B) a region of a connection between the attachment region ( 7c ) of the tether ( 7 ) and the inside ( 5b ) of the airbag ( 5 ), which upon deployment of the airbag ( 5 ) is exposed to the greatest tensile forces. Airbag according to claim 22, characterized in that the connection between the fastening area ( 7c ) and the inside ( 5b ) of the airbag ( 5 ) is formed by a seam. Airbag module for a motor vehicle with an airbag according to one of the preceding Claims.