WO2013028106A1

WO2013028106A1 - An impact protection device with different zones

Info

Publication number: WO2013028106A1
Application number: PCT/SE2011/051002
Authority: WO
Inventors: Florian Pucher; Ralf Zauritz
Original assignee: Autoliv Development Ab
Priority date: 2011-08-22
Filing date: 2011-08-22
Publication date: 2013-02-28
Also published as: EP2748038A4; EP2748038A1

Abstract

A vehicle pedestrian protection airbag (6) arranged to be inflated in the case of a pedestrian collision. The airbag (6) comprises an outer wall (10), enclosing a total volume (11), and at least one inner wall (12, 13) dividing the total volume (11) into a main partial volume (7) and at least one other partial volume (8, 9).The airbag (6) further comprises at least one valve part (15, 16) arranged to connect the main partial volume (7) with said other partial volume (8, 9). The valve part (15, 16) is arranged to admit air flow from the main partial volume (7) to said other partial volume (8, 9) and to prevent air flow from said other partial volume (8, 9) to the main partial volume (8). The airbag (6) is arranged to be inflated such that at least two different impact areas (2; 3, 4) of the vehicle exterior at least partly are covered with a corresponding partial volume (7; 8, 9). Each impact area (2; 3, 4) has certain impact area characteristics requiring certain corresponding airbag internal gas pressure characteristics.

Description

AN IMPACT PROTECTION DEVICE WITH DIFFERENT ZONES

DESCRIPTION OF THE INVENTION

The present invention relates to a vehicle pedestrian protection airbag arranged to be inflated by an inflating device in the case of a collision with a pedestrian. The airbag comprises an outer wall, enclosing a total volume, and at least one inner wall dividing the total volume into a main partial volume and at least one other partial volume. The main partial volume is connected to the inflating device. The airbag further comprises at least one valve part, each valve part being arranged to connect the main partial volume with said other partial volume. Said valve part is arranged to admit air flow from the main partial volume to said other partial volume and to prevent air flow from said other partial volume to the main partial volume.

Today, many vehicles are constructed to comprise at least one exterior airbag, intended to be inflated in the case of a collision with a pedestrian and to alleviate the collision force that the pedestrian is subject to.

JP 2008149785 discloses a pedestrian pillar air bag with cells that are arranged side by side or on top of each other in a symmetrical fashion. The cells are connected with non-return valves .

However, it is desired that several sections of a vehicle are airbag protected, in particular sections that are likely to hit a pedestrian in the event of a collision. However, different sections have different physical characteristics, offering different impact characteristics, which require different airbag inflation pressure requirements. It is an object of the present invention to provide a pedestrian airbag that is arranged for covering at least two different sections of a vehicle, which sections have different impact requirements which in turn results in different airbag inflation pressure requirements.

Said object is achieved by means of a vehicle pedestrian airbag arranged to be inflated by an inflating device in the case of a collision with a pedestrian. The airbag comprises an outer wall, enclosing a total volume, and at least one inner wall dividing the total volume into a main partial volume and at least one other partial volume. The main partial volume is connected to the inflating device. The airbag further comprises at least one valve part, each valve part being arranged to connect the main partial volume with said other partial volume. Said valve part is arranged to admit air flow from the main partial volume to said other partial volume and to prevent air flow from said other partial volume to the main partial volume. The airbag is arranged to be inflated such that at least two different impact areas of the vehicle exterior at least partly are covered with a corresponding partial volume. Each impact area has certain impact area characteristics requiring certain corresponding airbag internal gas pressure characteristics.

According to an example, each inner wall comprises a first layer and a second layer, the first layer facing the main partial volume and the second layer facing said other partial volume. According to another example, the first layer comprises at least one first layer aperture constituting a part of the valve part. Preferably, the second layer comprises at least one second layer aperture.

According to another example, when the airbag is inflated, the main partial volume is arranged to at least partly cover a windscreen of the vehicle. Said other partial volume comprises a first A-pillar partial airbag volume and a second A-pillar partial airbag volume. The A-pillar partial airbag volumes are arranged to at least partly cover corresponding A-pillars of the vehicle.

Other examples are evident from the dependent claims.

A number of advantages are obtained by means of the present invention. For example:

- a sufficient coverage with an even protection performance of the peripheral portions that uses a relatively small inflator, and - less amounts of airbag material needed, resulting in less package space.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described more in detail with reference to the appended drawings, where:

Figure 1 shows a schematic side view of a vehicle; Figure 2 shows a schematic top view of the front part vehicle ;

Figure 3 shows a schematic top view of the front part of a vehicle with an airbag according to the present invention inflated;

Figure 4 shows a schematic detail view of an airbag according to the present invention inflated;

Figure 5 shows a schematic view of inner wall parts;

Figure 6 shows a schematic view of assembled inner wall parts;

Figure 7a shows a schematic section view of an inner wall before pressurization;

Figure 7b shows a schematic section view of an inner wall during pressurization;

Figure 7c shows a schematic section view of an inner wall after completed pressurization; and

Figure 8 shows a schematic top view of the front part of a vehicle as in Figure 3, with an alternative airbag inflated .

DETAILED DESCRIPTION

With reference to Figure 1 and Figure 2, a vehicle 1 comprises a windscreen 2 and so-called A-pillars; a first A-pillar 3 at a right-hand side of the windscreen 2 and a second A-pillar 4 at a left-hand side of the windscreen 2. The A-pillars are well-known in the field of vehicles, and run to a roof 5 of the vehicle 1. The right-hand side and left-hand side are defined when viewing along the vehicle in its forward running direction D. In the event of a collision with a pedestrian, it is desirable that the pedestrian's impact with the vehicle is alleviated, and therefore, with reference to Figure 3, an external airbag 6 is mounted in such a way that when inflated it at least partly covers the windscreen 2 and the A-pillars 3, 4, the windscreen 2 and the A-pillars 3, 4 constituting impact areas. In this way, the inflated airbag 6 relieves some of the impact force .

However, due to the different material characteristics of the windscreen 2 and the A-pillars 3, 4, it is desirable that the airbag 6 also has different characteristics regarding internal gas pressure characteristics. In particular, the windscreen 2 has been found to be a suitable energy absorber and thus not so severe to hit as the A-pillars 3, 4.

According to the present invention, the airbag 6 is arranged to be inflated such that a main partial airbag volume 7 at least partly covers the windscreen 2, a first A-pillar partial airbag volume 8 at least partly covers the first A-pillar 3 and a second A-pillar partial airbag volume 9 at least partly covers the second A-pillar 4.

In this way, when the airbag 6 is inflated, different volumes 7, 8, 9 of the airbag 6 are arranged to at least partly cover different impact areas 2, 3, 4 of the vehicle exterior, each impact area 2, 3, 4 having certain impact area characteristics requiring certain corresponding airbag internal gas pressure characteristics. In this context, impact area characteristics may for example comprise ability to absorb energy, position on the vehicle and shape.

As will be described in the following, the different volumes 7, 8, 9 above are arranged to present such certain corresponding airbag internal gas pressure characteristics, matching the corresponding impact area characteristics. The present invention thus provides one entire pedestrian protection airbag (PPA) , covering impact areas with different characteristics and requirements; for example the windscreen portion is less severe to impact and on the same time constitutes a larger area than the A-pillar impact areas which are more sever to impact. The airbag 6 comprises an outer wall 10 made by a suitable fabric or other material, enclosing a total volume 11, a first inner wall 12 and a second inner wall 13. The first inner wall 12 constitutes a division between the main partial airbag volume 7 and the first A-pillar partial airbag volume 8. The second inner wall 13 constitutes a division between the main partial airbag volume 7 and the second A-pillar partial airbag volume 9. The main partial airbag volume 7 is connected to a gas generator 14 that is arranged to fill the airbag 6 with gas during a pressurization process at the event of a collision. The inner walls 12, 13 comprise one-way valves 15, 16, allowing gas to pass from the main partial airbag volume 7 to the A-pillar partial airbag volumes 8, 9, but not back again. The one-way valves 15, 16 are schematically indicated as dashed boxes in Figure 3.

At an impact scenario, during a first time period during pressurization of the airbag 6, the one-way valves 15, 16 are open and the total volume 11 constitutes an airbag system providing head injury protection.

During a second time period, when the airbag 6 has been pressurized, the one-way valves 15, 16 are closed, such that the airbag 6 comprises different impact zones.

If there is an impact in an A-pillar impact area 3, 4, each A- pillar partial airbag volume 8, 9 forms a small chamber with an inner pressure proportional to the pressure caused by the particular impact. This means that even an airbag with small depth and small amounts of pressurized gas provides good head injury protection, not bottoming out to the hard structure of the A-pillars 3, 4 and a vehicle chassis.

Preferably, but not necessarily, in order to reduce the rebound of the head, and thus a potential neck injury, caused due to the high pressured chamber, an additional aperture 17, 18 with an area of less than half of the one-way valve is introduced in each one of the inner walls 12, 13. The effect of the additional apertures 17, 18 is that the pressurized gas can flow back into the main partial airbag volume 7 in a controlled manner. The additional apertures 17, 18 are schematically indicated as dashed ovals in Figure 3.

The size of these additional apertures 17, 18, which each may comprise a number of sub-apertures, depends on parameters such as for example the total volume 11, the partial volumes 7, 8, 9, the capacity of the gas generator 14 and performance requirements. The benefit of this arrangement is that the A- pillar partial airbag volumes 8, 9 will function as a working system with the entire airbag 6 in all time sequences, reducing rebound effects, even though they are having a higher pressure than the main partial airbag volume 7.

If there is an impact in the windscreen impact area 2, the airbag 6 provides an additional membrane effect; a high pressure is not required in the main partial airbag volume 7 for achieving a suitable head protection. During impact, initially the inner pressure of the airbag 6 increases and the one-way valves 15, 16 open up the total volume 11 such that it has a relatively low pressure. This provides a suitable pedestrian protection, bottoming out may be allowed in this case, since the windscreen 2 functions as a sufficient energy absorber . In the following, an example of how the inner walls 12, 13 and the one-way valves 15, 16 may be constituted is disclosed.

In Figure 4, a detail 19 of the airbag 6 as shown in Figure 3 is shown cut-open. Here, the first inner wall 12 is shown, and according to this example, it is constituted by a first layer 20 and a second layer 21. The first layer 20, as shown in detail in Figure 5, is a first sheet of fabric 20 in which a number of apertures 22a, 22b, 22c, 22d have been made along a longitudinal extension L. The second layer 21 is a second sheet of fabric 21 which is slightly shorter than the first sheet of fabric 20 along the longitudinal extension L. The first sheet of fabric 20 has two edges 20a, 20b along the longitudinal extension L and two additional edges 20c, 20d. The second sheet of fabric 21 has two edges 21a, 21b along the longitudinal extension L and two additional edges 21c, 21d. For reasons of clarity, the edges 20a, 20b, 20c, 20d; 21a, 21b, 21c, 21d are only indicated in Figure 5, although they are present Figure 6 as well. In Figure 6, the first sheet of fabric 20 and the second sheet of fabric 21 are attached to each other by means of a first seam 23 and a second seam 24. The seams 23, 24 are indicated in Figure 4 and Figure 7a, Figure 7b and Figure 7c as having a certain extension between the sheets of fabric 20, 21; the seams 23, 24 are shown like this for reasons of clarity, while in practice they have little or none extension between the sheets of fabric 20, 21.

The seams 23, 24 run along the longitudinal edges 20a, 20b; 21a, 21b of the sheets of fabrics 20, 21, and due to the fact that the second sheet of fabric 21 is slightly shorter than the first sheet of fabric 20 along the longitudinal extension L, an opening 25, 26 is presented at each short side of the second sheet of fabric 21, along its additional edges 21c, 21d. Since all the edges 20a, 20b, 20c, 20d of the first sheet of fabric 20, and possibly the longitudinal edges 21a, 21b of the second sheet of fabric 21, are attached to the outer wall 10 of the air bag 6 when mounted, these openings 25, 26 are the only way for gas to pass between the main partial airbag volume 7 and the first A-pillar partial airbag volume 8. A similar arrangement, not shown, is present at the second wall 13.

The Figures 7a, 7b and 7c show a section of the first inner wall 12 through one of the apertures 22d in different states of pressurization. The same functionality is present at the second wall 13.

In Figure 7a, the airbag is not pressurized. In Figure 7b, the gas generator inflates the airbag such that gas flows through the aperture 22d in the direction of an arrow A, from the main partial airbag volume 7 to the first A-pillar partial airbag volume 8. In Figure 7c, the pressurization process is over, and the gas that has filled the first A-pillar partial airbag volume 8 is prevented from returning to the main partial airbag volume 7 by the second sheet of fabric 21 which covers the aperture 22d, the gas pressure in the first A-pillar partial airbag volume 8 exceeding the pressure in the main partial airbag volume 7. As discussed previously, in an alternative example, an additional aperture 17, 18 with the area of less than half of the one-way valve 15, 16 may introduced in the inner walls. Such an additional aperture may for example be introduced in the form of a number of apertures 17a, 17b, 17c, 17d in the second sheet of fabric 21 in each inner wall 12, 13 as indicated with dashed lines in Figure 5 and Figure 6 (not shown for the second inner wall 13) . Generally, the additional apertures 17a, 17b, 17c, 17d in the second sheet of fabric 21 constitute a second layer aperture 17, which may comprise one single aperture, or several sub-apertures.

The invention is not limited to the examples above, but may vary freely within the scope of the appended claims. For example, the inner walls 12, 13 may have any suitable form, each inner wall comprising one or more layers made in any suitable material and shape, for example oval. The one-way valves 15, 16 may be in the form of separate components that are attached to the corresponding inner wall 12, 13, generally constituting valve parts. The additional apertures may be any suitable opening in the corresponding inner walls.

The seams may be of any suitable kind, and may also instead be changed to other types of attachment, such as strings of glue. Any type of suitable material may be used in the airbag and its inner walls. The vehicle pedestrian airbag may be arranged to at least partly cover other impact areas, but at least comprises one main partial airbag volume and one other partial airbag volume . The gas generator is generally constituted by an inflating device .

The important features of the present invention is that an airbag comprises at least two partial volumes, separated with a one-way valve, where gas during pressurization passes the one-way valve, and is retained by the one-way valve after completed pressurization, such that the partial volumes have corresponding airbag internal gas pressure characteristics. In this way, different impact areas having different impact area characteristics can be at least partly covered by said partial volumes which have corresponding different internal gas pressure characteristics during pressurization, and after completed pressurization. The main partial airbag volume 7 preferably has an elongated tubular shape, and the A-pillar partial airbag volumes 8, 9, or said at least one other partial volume, each preferably has a volume in the span 10% - 20% of the total volume 11. An example of a certain value in said span is 14%.

Furthermore, the size of each additional aperture 17, 18 in mm² may relate to the volume capacity for each A-pillar partial airbag volume 8, 9 in liters. In that case, each additional aperture 17, 18 has a size in the span 20-100 mm for each liter of volume for each A-pillar partial airbag volume 8, 9, or generally for each of said at least one other partial volume. An example of a certain value in said span is 60 mm².

In other words, generally, said second layer aperture 17 defines a total aperture area which has a size ratio to each one of said other partial volume 8, 9 which size ratio is in the span of 20 - 100 mm² per partial volume liter.

The apertures 22a, 22b, 22c, 22d in the first layer 20 generally constitute a first layer aperture, which may comprise one single aperture, or several sub-apertures. When the airbag is not inflated, it is folded and stored in the vicinity of the gas generator 14.

In Figure 8, an example of an alternative airbag configuration is shown, where all parts that are the same as in Figure 3 have the same reference number. In Figure 8, the airbag 6' comprises a third inner wall 27, dividing the main partial volume 7 into a windscreen part volume 28 and a vehicle body part volume 29, as the third inner wall 27 extends between the first inner wall 12 and the second inner wall 13.

The third inner wall 27 does not completely divide the windscreen part volume 28 and the vehicle body part volume 29, for example the third inner wall 27 does not extend all the way between first inner wall 12 and the second inner wall 13, as indicated in Figure 8. In this way, gas is allowed to pass from the vehicle body part volume 29 to the windscreen part volume 28 during pressurization, but in a controlled manner, due to the limited passage or passages between the vehicle body part volume 29 and the windscreen part volume 28. Preferable, the valve parts 15, 16 are positioned in the vehicle body part volume 29. Thus, during pressurization, the vehicle body part volume 29 and the A-pillar partial airbag volumes 8, 9 are pressurized with more gas pressure than the windscreen part volume 28.

The benefit of this arrangement is to have the main partial volume 7 divided into two different volumes 28, 29, having different internal gas pressure characteristics. This is desirable, since the main partial volume 7 may not only cover the windscreen 2, but also a part of the vehicle body below the windscreen 2, this latter part constituting a harder part, more severe to hit, than the windscreen.

Thus the vehicle body part volume 29 and the A-pillar partial airbag volumes 8, 9 initially are pressurized with more gas pressure than the windscreen part volume 28, the vehicle body part volume 29 and the A-pillar partial airbag volumes 8, 9 at least partly covering parts of the vehicle that are more severe to hit than the windscreen 2 which is covered by the windscreen part volume 28.

Claims

1. A vehicle pedestrian protection airbag (6) arranged to be inflated by an inflating device (14) in the case of a collision with a pedestrian, the airbag (6) comprising an outer wall (10), enclosing a total volume (11), and at least one inner wall (12, 13) dividing the total volume (11) into a main partial volume (7) and at least one other partial volume (8, 9), where the main partial volume (7) is connected to the inflating device (14), the airbag (6) further comprising at least one valve part (15, 16), each valve part (15, 16) being arranged to connect the main partial volume (7) with said other partial volume (8, 9), where said valve part (15, 16) is arranged to admit air flow from the main partial volume (7) to said other partial volume (8, 9) and to prevent air flow from said other partial volume (8, 9) to the main partial volume (8), characterized in that the airbag (6) is arranged to be inflated such that at least two different impact areas (2; 3, 4) of the vehicle exterior at least partly are covered with a corresponding partial volume (7; 8, 9), each impact area (2; 3, 4) having certain impact area characteristics requiring certain corresponding airbag internal gas pressure characteristics .

2. A vehicle pedestrian protection airbag according to claim 1, characterized in that each inner wall (12, 13) comprises a first layer (20) and a second layer (21), the first layer (20) facing the main partial volume (7) and the second layer facing (13) said other partial volume (8, 9) .

3. A vehicle pedestrian protection airbag according to claim 2, characterized in that the first layer (20) comprises at least one first layer aperture (22a, 22b, 22c, 22d) constituting a part of the valve part (15, 16) .

4. A vehicle pedestrian protection airbag according to any one of the claims 1 or 2, characterized in that each second layer (13) comprises at least one second layer aperture (17; 17a, 17b, 17c, 17d) .

5. A vehicle pedestrian protection airbag according to claim 4, characterized in that said second layer aperture (17) defines a total aperture area that is less than half the area of the first layer aperture (22a, 22b, 22c, 22d) .

6. A vehicle pedestrian protection airbag according to any one of the claims 4 - 5, characterized in that said second layer aperture (17) defines a total aperture area which has a size ratio to each one of said other partial volume (8, 9), which size ratio is in the span of 20 - 100 mm² per partial volume in liters.

7. A vehicle pedestrian protection airbag according to any one of the previous claims, characterized in that the when the airbag (6) is inflated, the main partial volume (7) is arranged to at least partly cover a windscreen (2) of the vehicle (1), and that said other partial volume (8, 9) comprises a first A-pillar partial airbag volume (8) and a second A-pillar partial airbag volume (9), the A-pillar partial airbag volumes (8, 9) being arranged to at least partly cover corresponding A-pillars (3, 4) of the vehicle (1) .

8. A vehicle pedestrian protection airbag according to any one of the previous claims, characterized in that each one said other partial volume (8, 9) has a volume in the span% - 20% of the total volume (11) .