WO2004065180A1

WO2004065180A1 - An air-bag arrangement

Info

Publication number: WO2004065180A1
Application number: PCT/SE2004/000046
Authority: WO
Inventors: Rikard Fredriksson; Yngve Håland
Original assignee: Autoliv Development Ab
Priority date: 2003-01-22
Filing date: 2004-01-16
Publication date: 2004-08-05
Also published as: GB2397559A; GB0301467D0

Abstract

An inflatable air-bag arrangement on a motor vehicle is disclosed. The air-bag arrangement comprises an inflatable metal air-bag (11) and a gas generator (10) configured to inflate the air-bag (11). The air-bag (11) is configured and located on the motor vehicle (1) such that when the air-bag (11) is inflated, it extends at least partially over an A-pillar (3) of the motor vehicle (1) and at least partially over a region of the windscreen (4) of the motor vehicle adjacent to the A-pillar (3).

Description

"AN AIR-BAG ARRANGEMENT"

THE PRESENT INVENTION relates to an air-bag arrangement, and more particularly, relates to an air-bag arrangement for use on a motor vehicle.

If a pedestrian is hit by a motor vehicle, such as a motor car, the pedestrian may be severely injured, especially if the pedestrian impacts with specific areas of the car which are very rigid, and consequently dangerous. An area which is particularly dangerous is the area of the vehicle in the region of the A-pillar, including the part of the windscreen that is adjacent the A-pillar. It has therefore been proposed previously to provide an air-bag which, on inflation, is intended to cover the A-pillars and the region of the windscreen immediately adjacent the A-pillars, in order to provide some protection to a pedestrian in the event that the motor vehicle should collide with the pedestrian.

It has been proposed to use generally conventional fabric air-bags in air- bag arrangements intended to provide protection for a pedestrian in the event of an impact between a motor vehicle and a pedestrian. However, it has been found that such arrangements suffer from significant disadvantages. For example, the air-bags must have a substantial size, and the gas pressure within the air-bag must be relatively high, because otherwise the head of a pedestrian striking part of the air-bag would simply compress that part of the air-bag enabling the head of the pedestrian to strike the A-pillar or part of the windscreen. However, if the pressure within a fabric air-bag is high, there is a substantial risk of "rebound" occurring, with the head of a pedestrian striking the air-bag rebounding away from the air-bag in a very undesirable manner which can impart substantial injuries to the pedestrian. Some fabric air-bags are provided with ventilating apertures to prevent "rebound" but such ventilation apertures are not appropriate in an air-bag intended to cover an A- pillar, since the presence of such ventilation apertures would increase the risk that the head of a pedestrian would actually strike the A-pillar. Also, it is preferred that air-bags of this type should remain inflated for a relatively long period of time as compared with a typical air-bag within a motor vehicle, again making ventilation apertures undesirable.

Another problem with conventional fabric air-bags provided externally on a motor vehicle in order to protect a pedestrian, is that the fabric of the air- bags is sensitive to the environment. For example, if such an air-bag is positioned beneath the bonnet or hood in the scuttle region of a motor vehicle, the air-bag would be exposed to weather conditions, dirt, water etc. which can have a significant degrading effect on the fabric of the air-bag.

Another problem associated with externally-mounted air-bags intended to protect pedestrians, is one of instability. For example, an inflated air-bag secured to a motor vehicle only via the gas inlet to the air-bag, (as is conventional) can sway from side to side and move out of position, especially if the motor vehicle is decelerating or m-iking a violent turning movement to one side in order to avoid colliding with a pedestrian. This instability means that the inflated fabric air-bag can move out of its most effective position, thereby reducing its effectiveness in ensuring that the head of a pedestrian does not strike the A-pillar or the region of the windscreen immediately adjacent the A- pillar.

It is therefore an object of the present invention to provide an improved air-bag arrangement.

Accordingly, the present invention provides an air-bag arrangement on a motor vehicle, the air-bag arrangement comprising: an inflatable metal air-bag and a gas generator to inflate the air-bag, the air-bag being configured and located on the motor vehicle such that when the air-bag is inflated, it extends at least partially over an A-pillar of the motor vehicle and at least partially over a region of a windscreen of the motor vehicle adjacent the A-pillar.

Preferably, the metal air-bag is plastically deformable.

Advantageously, the air-bag is of stainless steel.

Conveniently, the air-bag comprises two superimposed sheets of metal, the sheets being interconnected by a welded seam.

Preferably, each sheet has a thickness no greater than 0.25 mm.

Advantageously, the two sheets are of different sizes.

Conveniently, the air-bag and gas generator are positioned within a recess formed in the A-pillar. Preferably, the air-bag and gas generator are each mounted to the A- pillar, within the recess, by a hinge configured to allow the gas generator and air-bag to move away from the A-pillar as the air-bag is inflated.

Advantageously, the air-bag is rolled or folded into a package and is located behind a cover which closes the recess.

Conveniently, the air-bag is rolled so as to have a diameter of 20 to 70 mm.

Preferably, the cover is of plastics material.

Advantageously, the cover forms part of the air-bag.

Conveniently, said package has two distinct parts, one of said parts being located adjacent the windscreen of the motor vehicle and the other part being located adjacent the outboard side of the A-pillar, said one part being larger than said other part.

Preferably, the air-bag is positioned beneath a bonnet or hood of the motor vehicle.

Advantageously, the air-bag is provided with a vent hole.

Conveniently, said vent hole is provided in said seam.

Preferably, said vent hole is provided through one of said sheets. Advantageously, the air-bag is configured to have a maximum thickness when inflated of 50 to 200 mm.

Conveniently, the air-bag is configured to extend from the A-pillar across the windscreen by a distance of 75 to 200 mm when inflated.

So that the present invention may be more readily understood, and so that further features thereof may be appreciated, embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 is a schematic side view of a motor vehicle, illustrating an air-bag arrangement in accordance with the present invention, mounted within the A-pillar of a motor vehicle; FIGURE 2 is a schematic view from above, illustrating the air-bag initially packed within the A-pillar in accordance with a first embodiment;

FIGURE 3 is a view corresponding generally to that of Figure 2, but illustrating the air-bag packed in accordance with a further embodiment;

FIGURE 4 is a schematic side-view, of the A-pillar region of the motor vehicle illustrated in Figure 1, illustrating the air-bag in a deployed condition in which it has been inflated;

FIGURE 5 is a schematic plan view from above, illustrating the deployed air-bag of Figure 4 in position over the A-pillar of a motor vehicle;

FIGURE 6 is a schematic view looking down the A-pillar, illustrating the deployed air-bag extending outwardly from the A-pillar and partially across the windscreen of the motor vehicle;

FIGURE 7 is a view corresponding generally to that of Figure 4, but illustrating an inflated air-bag in accordance with a further embodiment of the present invention; FIGURE 8 is a view corresponding to that of Figure 6, but illustrating the air-bag of the embodiment illustrated in Figure 7 in its deployed condition; and

FIGURE 9 is a schematic side view of a motor vehicle, illustrating an air-bag arrangement in accordance with another embodiment of the present invention, installed beneath the scuttle region of the hood or bonnet of a motor vehicle.

Figure 1 illustrates a motor vehicle 1 of generally conventional form, havmg a bonnet or hood 2 and a pair of A-pillars 3 (only one illustrated in Figure 1) extending upwardly from the region of the rearmost part of the bonnet 2, along respective side edges of the vehicle windscreen 4 (the windscreen being illustrated in Figure 2). A door aperture 5 is illustrated schematically in Figure 1.

The A-pillar 3 comprises a generally U-shaped channel 6 having a pair of forwardly-extending flanges 7 defining a recess 8 therebetween. The channel

6 preferably runs the entire length of the A-pillar 3, although it should be appreciated that the channel 6, and hence also the recess 8, may only extend part-way along the A-pillar 3.

An air-bag unit 9 is located wimήi the recess 8 of the A-pillar 3 and comprises an inflator in the form of a gas generator 10 and an inflatable air-bag

11 fluidly connected to the gas generator 10. The gas generator 10 is mounted within the recess 8 defined by the channel 6 at the lowermost end of the A- pillar 3.

The air-bag 11 is made out of metal, and most preferably of stainless steel. The air-bag 11 comprises a pair of superimposed metal sheets having a thickness of preferably no more than 0.25 mm, which are interconnected around their edges by a peripheral weld to form a seam 12 as illustrated most clearly in Figure 4. An inlet aperture is formed in the seam 12, which accommodates part of the gas generator 10. The metal air-bag 11 is connected to the gas generator 10 by crimping the metal sheet material of the air-bag on to the body of the gas generator 10. A vent hole 13 (also shown in Figure 4) is also formed in the seam 12, in a region of the air-bag adjacent the gas generator 10. However, it should be appreciated that the vent hole 13 could be provided in one or other of the metal sheets instead of in the seam 12.

As illustrated in Figure 2, the air-bag 11 is initially folded into a package so that the air-bag 11 can be entirely received within the recess 8 and retained behind a cover 14 which may be plastic or metal and which is fitted between the two flanges 7 of the channel 6, in order to provide a flush forwardmost surface to the A-pillar 3. The air-bag package located within the recess 8 comprises two distinct parts 15,16. The first package part 15 extends from slightly outboard of the centrally- located gas generator 10 and comprises a series of zig-zag folds, the folds being oriented so as to be substantially parallel to the longitudinal axis of the channel 6. The second package part 16 extends inboard of the gas generator 10 and is hence located adjacent the windscreen 4 of the motor vehicle. The second, or inboard, package part 16 again comprises a series of zig-zag folds oriented so as to be substantially parallel to the longitudinal axis of the channel 6. However, it should be appreciated from Figure 2, that the inboard package part 16 is larger than the outboard package part 15, and hence comprises a higher number of zig-zag folds. Alternatively, the inboard package part 16 could comprise the same number of folds as the outboard package part 15, in which case the inboard part 16 could be made larger than the outboard part by using wider folds. Turning briefly to consider Figure 3, an alternative form of air-bag package is illustrated. This configuration of air-bag package again comprises two distinct package parts, namely an outboard package part 17 and an inboard, larger, package part 18 located adjacent the windscreen 4. In this arrangement, the two-package parts 17,18 are each rolled about a respective axis lying substantially parallel to the longitudinal axis of the channel 6. However, because the air-bag 11 is made of metal, and most preferably stainless steel, it is important that the two-package parts 17,18 are not rolled too tightly because rolling the package parts too tightly can introduce sharp folds or creases into the metallic sheets making up the air-bag 11 which can introduce weaknesses into the air-bag. It is therefore preferred that the rolled package parts 17,18 have a diameter of between 20 and 70 mm. This provides a convenient balance between ensuring that the metallic sheets making up the air-bag 11 are not undesirably creased, whilst also ensuring that the package parts are sufficiently tightly rolled to be properly received within the recess 8, behind the plastic cover 14.

Upon receipt of an appropriate signal from an impact detector, the gas generator 10 is actuated which causes a large volume of gas to be injected into the initially folded or rolled air-bag 11, causing the air-bag to inflate as illustrated in Figure 4. As the air-bag 11 inflates, it deforms plastically and ruptures or releases the plastic cover 14 extending across the recess 8, and, because of the location of the gas generator 10 against the rearmost surface of the channel 6, is caused to pivot forwardly slightly about the gas generator 10 to adopt the position illustrated in Figure 4. As the air-bag approaches its full inflated condition, the part of the air-bag provided with the vent hole 13 becomes unfolded and hence the vent hole 13 becomes unobstructed to allow the gas inside the air-bag to vent to atmosphere if the inflated air-bag subsequently should be deformed plastically by impact with a pedestrian. It will be seen, that the maximum thickness of the inflated air-bag 11 is indicated by t in Figure 4. It has been found that the most appropriate thickness t for the fully inflate air-bag is somewhere between 50 to 200 mm, which offers sufficient protection to pedestrians.

As illustrated in Figure 5, the inflated air-bag 11 serves to cover substantially the entire extent of the A-pillar 3, and also to extend inboard of the A-pillar 3, so as to extend over the region of the windscreen 4 located immediately adjacent the A-pillar 3. Figure 6 illustrates this inflation characteristic more clearly, when viewed looking down the channel 6 of the A- pillar 3 from above. Because the two-package parts 15, 16 (or 17, 18) are of different sizes, with the inboard package part being larger than the outboard package part, the inflated air-bag 11 extends further inboard of the channel 6, across the windscreen 4, than it extends outboard of the channel 6. This is because it is unnecessary for the inflated air-bag 11 to extend outboard of the A-pillar, but it is important for the inflated air-bag 11 to extend a distance d across the region of the windscreen 4 immediately adjacent the A-pillar 3, because this region of the windscreen is substantially rigid and will not absorb sufficient energy from the inertia of a pedestrian, to prevent injuring the pedestrian. It has been found that the air-bag 11 provides sufficient protection to a pedestrian striking this region of the windscreen 4, if the air-bag extends a distance d in the range of 75 to 200 mm across the windscreen 4, when fully inflated.

It will therefore be seen that the air-bag 11, when fully inflated as illustrated in Figures 4 to 6, extends over the A-pillar 3 of the motor vehicle 1, and over a region of the windscreen 4 irnmediately adjacent the A-pillar 3, and so serves to protect a pedestrian striking these regions of the motor vehicle in the event of an impact between the motor vehicle and the pedestrian. The metal of the air-bag 11 is plastically-deformable and so deforms in a plastic manner as the air-bag 11 is inflated. Because the air-bag 11 is made of sheet metal, rather than conventional woven fabric, the inflated air-bag 11 is significantly more stable than it would be if made from fabric, and hence is less likely to sway or move out of position across the A-pillar as the vehicle decelerates or turns violently. Also, the air-bag will not collapse, as the vent hole 13 allows the gas within the air-bag to vent, unless struck by a pedestrian.

As the inflated air-bag 11 is struck by a pedestrian, then the metal sheet of the air-bag 11 again deforms plastically, to perform an improved energy absorption function when compared to a conventional fabric air-bag which, as explained above, suffers from problems of "rebound". A significantly higher gas pressure is required to inflate the metal air-bag than that required to inflate a fabric air-bag. The gas pressure required depends upon the thickness of the metal sheet material, but tests have shown that an mflating pressure of approximately 600 kPa is no unusual. The pressure applied to the air-bag by the weight of a pedestrian is typically only approximately 15-30 kPa. The vent hole allows the high pressure gas to vent when the air-bag has been inflated and also allows sufficient deformation of the air-bag when struck by a pedestrian.

The "rebound" effect of the metallic air-bag 11 is therefore significantly reduced over that of the conventional fabric air-bag. Also, of course, the metal air-bag 11, being made preferably of stainless steel, is not adversely affected by weather conditions, such as degradation by rain or moisture.

Figures 7 and 8 illustrate an alternative embodiment of the above- described air-bag arrangement, in which both the gas generator 10 and the metal air-bag 11 are secured within the recess 8 of the A-pillar 3 by a respective hinge 19. The hinges 19 are initially folded flat so that the gas generator 10 and the initially folded or rolled air-bag 11 lie well within the recess 8. However, as the air-bag 11 is inflated (as illustrated in Figures 7 and 8) the hinges 19 open up, thereby allowing the gas generator 10 and the air-bag 11 to move away from the back part of the recess 8 so that they begin to move out of the recess 8 in a forwards manner. This has been found to be advantageous in that the inflated air-bag is effectively lifted out of the A-pillar recess and is thereby not significantly obstructed by the opening of the recess 8. This principle can be easily seen by comparing Figure 8 with Figure 6, in which the gas generator 10 is secured directly to the channel 6 defining the recess 8, without any hinge 19. It has also been found that the hinge 19 securing the air-bag 11 to the channel 6 defining the recess 8, serves as a strap to hold down the air-bag, and hence prevent the tilting movement described above and illustrated in Figure 4. In this regard, even if no hinges 19 are employed, it has been found that in certain installations, it can be beneficial to secure the air-bag 11 directly to the A-pillar 3, for example by welds, bolts or the like, in addition to the connection between the gas generator 10 and the A- pillar, in order to provide additional stability to the inflating air-bag, and prevent the above-mentioned tilting movement as illustrated in Figure 4.

Whilst the present invention has been described above with reference to particular arrangements, it should be appreciated that certain modifications could be effected to the arrangements, without departing from the scope of the present invention. For example, whilst the above-mentioned embodiments all involve folding or rolling of the air-bag 11 around axes lying substantially parallel to the longitudinal axis of the A-pillar 3, in order to initially pack the air-bag within the recess 8 of the A-pillar 3, it is also envisaged that in certain instances, it may be more appropriate to provide the air-bag below the rear part of the bonnet or hood 2 of the motor vehicle 1. Such an arrangement is illustrated schematically in Figure 9, where it will be seen that a metal air-bag 20 is provided, together with its associated gas generator 21, below the rear part of the hood or bonnet 2 of the motor vehicle 1, in the "scuttle" region of the motor vehicle, adjacent the lower part of the A-pillar 3. In such an installation, the air-bag 11 is initially rolled, or folded, about an axis running substantially horizontally and transversely across the motor vehicle 1.

In the present specification "comprises" means "includes or consists of and "comprising" means "including or consisting of.

Claims

CLAIMS:

1. An air-bag arrangement on a motor vehicle, the air-bag arrangement comprising: an inflatable metal air-bag and a gas generator to inflate the air- bag, the air-bag being configured and located on the motor vehicle such that when the air-bag is inflated, it extends at least partially over an A-pillar of the motor vehicle and at least partially over a region of a windscreen of the motor vehicle adjacent the A-pillar.

2. An air-bag arrangement according to claim 1, wherein the metal air-bag is plastically deformable.

3. An air-bag arrangement according to claim 1 or claim 2, wherein the air- bag is of stainless steel.

4. An air-bag arrangement according to any preceding claim, wherein the air-bag comprises two superimposed sheets of metal, the sheets being interconnected by a welded seam.

5. An aii-bag arrangement according to claim 4, wherein each sheet has a thickness no greater than 0.25mm.

6. An air-bag arrangement according to claim 5, wherein the two sheets are of different sizes.

7. An air-bag arrangement according to any preceding claim, wherein the air-bag and gas generator are positioned within a recess formed in the A-pillar.

8. An air-bag according to claim 7, wherein the air-bag and gas generator are each mounted to the A-pillar, within the recess, by a hinge configured to allow the gas generator and air-bag to move away from the A-pillar as the air- bag is inflated.

9. An air-bag arrangement according to claim 7 or claim 8, wherein the air- bag is rolled or folded into a package and is located behind a cover which closes the recess.

10. An air-bag arrangement according to claim 9, wherein the air-bag is rolled so as to have a diameter of 20 to 70 mm.

11. An air-bag arrangement according to claim 9 or claim 10, wherein the cover is of plastics material.

12. An air-bag arrangement according to claim 9 or claim 10, wherein the cover forms part of the air-bag.

13. An air-bag arrangement according to any one of claims 9 to 12, wherein said package has two distinct parts, one of said parts being located adjacent the windscreen of the motor vehicle and the other part being located adjacent the outboard side of the A-pillar, said one part being larger than said other part.

14. An air-bag according to any one of claims 1 to 7, wherein the air-bag is positioned beneath a bonnet or hood of the motor vehicle.

15. An air-bag arrangement according to any preceding claim, wherein the air-bag is provided with a vent hole.

16. An air-bag arrangement according to claim 15 as dependant upon claim 4, wherein said vent hole is provided in said seam.

17. An air-bag arrangement according to claim 15 as dependant upon claim 4, wherein said vent hole is provided through one of said sheets.

18. An air-bag arrangement according to any preceding claim, wherein the air-bag is configured to have a maximum thickness when inflated of 50 to 200mm.

19. An air-bag arrangement according to any preceding claim, wherein the air-bag is configured to extend from the A-pillar across the windscreen by a distance of 75 to 200mm when inflated.