WO2017182602A1

WO2017182602A1 - Frontal airbag for installation into a motor vehicle

Info

Publication number: WO2017182602A1
Application number: PCT/EP2017/059457
Authority: WO
Inventors: Marc Schock
Original assignee: Autoliv Development Ab
Priority date: 2016-04-22
Filing date: 2017-04-21
Publication date: 2017-10-26
Also published as: DE102016107484A1; DE102016107484B4

Abstract

A frontal airbag for installation into a motor vehicle is described. This frontal airbag comprises a main cushion (12) extending horizontally in a first direction (Y) when the frontal airbag is in its fully deployed state, and said main cushion has a front area (14). Further, an additional impact layer (22) covering at least a part of the front area (14) of the main cushion (12) is provided. In order to improve the protection of the person to be protected during a laterally offset frontal crash, the additional impact layer (22) is in sliding connection with the main cushion (12), such that it is displaceable relative to the front area (14) of the main cushion at least in the first direction (Y) without a deformation of the main cushion (Fig. 2).

Description

Frontal airbag for installation into a motor vehicle

Description

The invention relates to a frontal airbag for installation into a motor vehicle according to the preamble of claim 1.

A generic frontal airbag is for example known from US 6,554,313 B2.

Frontal airbags are widespread in today's automotive technology. They are the first kind of airbags introduced into the automotive technology and are still key elements of the safety system of a motor vehicle especially of a passenger car. The use of frontal airbags saves thousands of lives every year.

Although the present invention can be applied to both, to so-called driver air- bags deploying in front of the steering wheel of the motor vehicle as well as to so-called passenger airbags deploying in front of a part of the instrument panel, reference is primary made to passenger airbags since the most relevant application for the current invention are passenger airbags. But it needs to be noted that the application can also be applied to so-called driver airbags.

The task of a frontal airbag is to protect the head and the thorax of the person sitting in front of this frontal airbag. In case of a "pure" frontal crash (meaning that the vehicle hits another object symmetrically with its front) the deceleration of the car occurs only in the travelling direction of the car (denoted as the X- direction). This is the most often case of a frontal crash and consequently frontal airbags are optimised for this case. In this load case the person hits the front area of the frontal airbag in a simple linear motion such that no lateral forces act between the frontal airbag and the person. The situation changes in the case of a laterally offset frontal crash. This is now explained by means of the most important case in which reference is made to a left-handed car: - -

It happens relatively often that the car hits an object (especially another car driving in the opposite direction) with its front left edge. This leads to a motion of the person(s) sitting in the vehicle to the front and to the left (relative to the vehicle). For the passenger sitting next to the driver this means that she/he moves forward and to the inside (away from the right side window). This can lead to the following: The head of the passenger hits the impact surface of the frontal air- bag the head is held by the same because of frictional forces, but the body of the passenger moves towards the inside of the car. This can lead to a very quick rotation of the head and/or to high forces in the neck of the passenger. Both can have negative consequences.

It is the task of the invention to provide a frontal airbag which shows an improved protection of the person to be protected during a laterally offset frontal crash.

This task is solved by a frontal airbag with the features of claim 1.

An additional impact layer covering at least a part of the front area of the main cushion is provided. According to the invention this additional impact layer is in a sliding connection with the main cushion, such that it is displaceable relative to the front area of the main cushion at least in the first (lateral) direction. The ability of the additional impact layer of being laterally displaced relative to the main cushion is such that it can take place without a deformation of the main cushion. In other words: This ability is a property of the additional layer and its connection to the main cushion itself.

By providing a laterally displaceable additional impact layer the head of the occupant can couple to the frontal airbag - namely the additional impact layer - and stay coupled to the same and can follow the body of the occupant by its lateral movement. By this the protection provided by the frontal airbag is fully maintained but the angular momentum acting on the head and the lateral force acting on the neck are strongly reduced. - -

The additional impact layer can be a part of an additional airbag placed onto the front area of the main cushion, said additional airbag enclosing a separate gas space. In a mechanically simpler embodiment there is no or at least no permanently closed separate gas space and the additional impact layer is in direct or almost direct contact to the front area of the main cushion. These two basis concepts will now be described in detail.

The drawings show:

Figure 1 the passenger side of a motor vehicle with a fully deployed frontal airbag according to a first embodiment of the invention at an early stage of a frontal crash before the passenger starts moving towards this frontal airbag in a strongly schematised vertical cross- section,

Figure 2 the cross-section taken along plane A-A in Figure 1 ,

Figure 3 a plan view onto the frontal airbag of Figure 1 from direction B (the view the passenger has to the frontal airbag),

Figure 4 what is shown in Figure 2 after the head of the passenger hit the frontal airbag,

Figure 5 what is shown in Figure 4 at a later stage,

Figure 6 basically what is shown in Figure 1 in a top view,

Figure 7 the situation of Figure 5 in a representation according to Figure 6,

Figure 8 a variation of the first embodiment in a representation according to

Figure 4, _ _

Figure 9 a further variation of the first embodiment in a representation according to Figure 8,

Figure 10 another variation of the first embodiment of the invention in a representation according to Figure 2,

Figure 11 a second embodiment of the invention in a representation according to Figure 2,

Figure 12 the embodiment of Figure 11 in a representation according to Figure 3,

Figure 13 the additional airbag of the second embodiment in a schematic perspective view,

Figure 14 the frontal airbag of the second embodiment in the stage according to Figure 4,

Figure 15 what is shown in Figure 14 in a stage according to Figure 5,

Figure 16 the second embodiment of the invention in a representation according to Figure 6,

Figure 17 what is shown in Figure 16 in a stage basically according to Figure

15,

Figure 18 a variation of the second embodiment,

Figure 19 an alternative design of the second embodiment in a representation according to Figure 14, and

Figure 20 the frontal airbag of Figure 19 in a stage and representation according to Figure 15. - -

As has already been mentioned two main embodiments are described hereinafter. First, the first embodiment is described in view of Figures 1 to 7. Then, variations of the first embodiment are described in view of Figures 8 to 10. After this the second embodiment is described in view of Figures 11 to 17. Figure 18 shows a variation of the second embodiment.

In Figure 1 one sees a passenger 40 seated on a seat in front of an instrument panel 44 and a wind shield 46. A frontal airbag 10 is originally stored in a housing located inside the instrument panel 44. The Figure 1 shows the fully deployed state of this frontal airbag 10. This frontal airbag 10 extends in all three dimensions such that it has a height in the vertical (Z-direction) and a width in the lateral direction of the car (the Y-direction (see Figure 3)). This lateral direction is also referred to as the first direction. The frontal airbag comprises a main cushion 12 which has a front area 14 pointing towards the passenger 40. This front area 14 has an upper part 14a and a lower part 14b. As is standard with frontal airbags, a ventilation device is provided in the main cushion, here in form of a simple vent hole 16. As one can schematically see in Figure 1 , an additional impact layer 22 covers at least a part (here most of the same) of the upper part 14a of the front area 14 of the main cushion.

In the embodiment shown in Figures 1 to 5 a plurality of small openings 28 are provided in the upper part 14a of a front area 14 below the additional impact layer 22, but this might not be the case in all possible variations as will be seen later.

As can best be seen from Figure 2 the additional impact layer is a part of a supplemental element 20 which can be made of a standard airbag material or another flat material (like a fabric or a foil). It is preferred that this supplemental element 20 is made from a single cutting. Additionally to the additional impact layer 22 this supplemental element 20 comprises a first side section 23a which is located on the vehicle outer side of the frontal airbag (on the right side in case of a left-handed vehicle) as can best be seen from Figure 3. A part of the addi- - - tional impact layer 22 and this first side section 23a form a "IT such that a double layered section of the supplemental element 20 is formed. This section could also be denoted as an open loop. The end of the first side section 23a and the remote end of the additional impact layer 22 are connected to the main cushion 12 by means of permanent connections 24a, 24b which extend preferably parallel to each other. The permanent connection 24a of the first side section 23a is covered by the additional impact layer 22 such that in Figure 3 it is represented by a line in the pattern dash-point-point-dash. It is essential that the overall width (in Y-direction) of the supplemental element 20 exceeds the distance between the two permanent connections 24a, 24b. Additionally the loop is secured to the main cushion 12 by means of a tear connection 26 (usually a tear seam).

The function of the supplemental element and especially the additional impact layer 22 can best be seen in view of Figures 4, 5, 6 and 7. When the head 42 of the passenger 40 hits the frontal airbag 10 it comes exclusively into contact to the additional impact layer 22. Because of frictional forces between this additional impact layer 22 and the head 40, the head will not move relative to this additional impact layer 22 even if the body of the passenger starts moving in a lateral direction (in this case towards the inside of the vehicle). So the body applies a force to the head 22 and the head 42 applies a force to the additional impact layer 22. Because of this force the tear connection 26 tears and the loop becomes loose such that the additional impact layer 22 can slide over the upper part of the front area 14 of the main cushion 12 in Y-direction. Consequently the head 42 can "follow" the body of the passenger without sliding over the additional impact layer 22 or losing its contact to the same. This means that the head 42 can follow the body while being coupled to the frontal airbag with the forces acting on the neck are strongly reduced and with the head being not forced to rotate.

Since the additional impact layer 22 lies basically onto a section of the front area 14 of the main cushion 12, it is preferred that measures are taken which reduce the friction between those two elements. One possibility is to provide an air cushion between the additional impact layer 22 and the front area 14 of the main cushion 12. For this purpose a plurality of small openings 28 is provided in the front area 14 under the additional impact layer 22 as is shown in Figures 1 to 5. Since there is no connection between upper and lower edge of the additional impact layer 22 and the front area 14, gas streaming through these openings 28 is not confined between the additional impact layer 22 and the front area 14 but of course a slight overpressure is present which reduces the frictional forces. But, as can be seen for example from Figure 8, such openings 28 might not be necessary in all applications. Other measures to reduce the friction can for example be the providing of a friction reducing coating on the surface of the additional impact layer 22 pointing towards the front area 14 and/or on the surface of the front area 14 pointing to the additional impact layer 22. Of course presence of the openings 28 can be combined with such an anti-friction coating. A friction reducing coating can for example be made of Teflon.

The frontal airbag shown in Figures 1 to 8 is asymmetric and optimised for the load case in which the vehicle hits another object with its front left corner. This is the most important application of this invention (in case of left handed- vehicles) for the following reasons: First, these kinds of accidents are statistically much more relevant than accidents in which the vehicle hits another object with its right front corner. Second, often a side- or curtain airbag is provided which limits the movement of the body to the outside of the car. This also limits the force acting between the body and head. Nevertheless, the frontal airbag can also be designed symmetrically as is shown in Figure 9. Here, two side sections 23a, 23b are present, such that the supplemental element 20 is made up of the additional impact layer 22 and the two side sections 23a, 23b. As one can easily see from Figure 9 the additional impact layer 22 can move into both Y- directions (to the left and to the right). As described above it is preferred that the supplemental element 22 is made of a single cutting. The openings 28 shown in Figure 10 are optional as in the asymmetrical case. It would also be possible to form the supplemental element as a closed loop and to secure the same to the front area by means of a single permanent connection. In this case openings in the front area would not be useful. - -

Especially if openings 28 are present it can be advantageous to connect the upper and lower edge of the supplemental element 22 at least partially (preferably completely) to the front area 14 of the main cushion 12 by means of additional tear connections 27a, 27b which extend in the first direction (Y-direction). By this measure the space between the additional impact layer 22 and the front area 14 is initially filled with gas such that the additional impact layer 22 and the front area 14 are spaced apart from another when the head 40 hits the additional impact layer 22. This helps to further reduce the initial friction between those elements. When the head 42 applies a force to the additional impact layer 22 in the first direction, these additional tear connections 27a, 27b tear and the additional impact layer 22 can move in a sliding manner as described above (Figure 10).

Figures 11 to 18 show a second embodiment of the invention. As in the embodiment of Figure 9 a supplemental element 20 having an additional impact layer 22 and two side sections 23a, 23b is provided, as can best be seen from Figure 11. In contrast to the first embodiment the supplemental element and thus the additional impact layer 22 are a part of an additional airbag 30 which encloses a gas space separate from the gas space enclosed by the main cushion 12. For this purpose this additional airbag 30 further comprises two side panels 32a, 32b which are attached to the supplemental element 20. The supplemental element 20 forms a full circle such that it can be attached to the front area 14 of the main cushion 12 by a single permanent connection 24. In the embodiment shown in Figures 11 to 17 only one such permanent connection 24 is provided. This permanent connection 24 encircles a single opening 28 forming an overflow opening between the gas space of the main cushion 12 and the gas space of the additional airbag 30. So, the supplemental element 20 shows the additional impact layer 22 and a section which is basically parallel (in the widest sense) to this additional impact layer 22 and abuts the front area 14 of the main cushion 12. According to the definitions chosen this section belongs to the side sections (23a, 23b). As is shown in Figures 11 and 13 the side panels 32a, 32b can be contoured, for example such that the additional impact layer 22 has a step (as shown) or a recess at the position in which the head 42 is likely to hit the additional impact layer 22.

The diameter of overflow opening 28 should be chosen such that the pressure in the gas space of the additional airbag 30 is lower than in the main cushion 12. The pressure inside the additional airbag 30 can for example be about 0,05 bars. Venting openings can be provided in the additional airbag 30.

Due to the geometry and the low pressure inside the additional airbag 30 the additional impact layer 22 can slide relative to the front area 14 of the main cushion as is the case in the first embodiment by a sort of a rolling movement of the additional airbag over the main cushion. This is shown in Figures 14 to 17. The main difference to the first embodiment is that the additional impact layer 22 has a larger distance from the front area 14 of the main cushion 12 and that a permanent air cushion is provided such that frictional forces acting against the sliding movement are very low. An additional positive effect can take place when the head 42 of the dummy moves relative to the main cushion 12. One can see especially from Figures 15 and 17 that a bulge can pile up which helps to prevent the head from slipping off the additional impact layer 22.

As can be seen from Figure 18 more than one overflow opening 28 can be present. In this case it is preferred that the overflow openings 28 are located on a line perpendicular to the first direction (Y-direction). This helps to make sure that the sliding movement of the additional impact layer 22 can take place only in the first direction as is the case in the first embodiment. Alternatively an oblong overflow opening extending perpendicularly to the first direction could be provided.

Figures 19 and 20 show another alternative design. Here, the overflow open- ing(s) is/are not located in the middle (regarding the Y-direction of the front area 14 of the main cushion 12, but offset of this position, especially towards the middle of the vehicle. By this measure even more sliding range can be gained. „

- 10 -

List of reference numbers

10 Frontal airbag

12 Main cushion

14 front area

14a upper part

14b lower part

16 vent hole

20 supplemental element

22 additional impact layer

23a first side section

23b second side section

24, 24a, 24b permanent connection

26, 26a, 26b tear connection

27a, 27b additional tear connection in first connection

28 opening

30 additional airbag

32a, b side panel

40 dummy

42 Head of dummy

44 instrument panel

46 windshield

48 seat

Y first direction

Z second direction

Wmax maximum width

Hmax maximum height

Claims

1. Frontal airbag (10) for installation into a motor vehicle, comprising:

a main cushion (12) extending horizontally in a first direction (Y) when the frontal airbag (10) is in its fully deployed state, said main cushion having a front area (14);

an additional impact layer (22) covering at least a part of the front area (14) of the main cushion (12),

characterized in that the additional impact layer (22) is in sliding connection with the main cushion (12), such that it is displaceable relative to the front area (14) of the main cushion (12) at least in the first direction (Y) without a deformation of the main cushion.

2. Frontal airbag according to claim 1 , characterized in that the additional impact layer (22) is displaceable relative to the front area (14) only in the first direction (Y), not perpendicular to the same.

3. Frontal airbag according to one of the preceding claims, characterized in that the additional impact layer (22) is in the first direction (Y) displaceable relative to the front area (14) of the main cushion (12) by an amount of at least 10 cm, preferably of at least 20 cm.

4. Frontal airbag according to one of the preceding claims, characterized in that at least one side section (23a, 23b) extends from the additional impact layer (22) such that a supplemental element (20) is formed which is connected to the main cushion (12).

5. Frontal airbag according to claim 4, characterized in that the supplemental element (20) is a single cutting.

6. Frontal airbag according to claim 4 or claim 5, characterized in that the supplemental element (20) is connected to the main cushion (12) via a first permanent connection (24a) and a second permanent connection (24b) being spaced from another in the first direction (Y).

7. Frontal airbag according to claim 4 or claim 5, characterized in that the supplemental element (20) is connected to the main cushion (12) via a single permanent connection (24) or via more than one permanent connection not being spaced from another in the first direction (Y).

8. Frontal airbag according to one of the claims 4 to 6, characterized in that the total length of the supplemental element (20) in the first direction (Y) exceeds the distance between the first and the second connection (24a, 24b).

9. Frontal airbag according to one of the claims 4 to 8, characterized in that the additional impact layer (22) is not directly permanently connected to the main cushion (12).

10. Frontal airbag according to one of the claims 4 to 9, characterized in that the supplemental element (20) is additionally connected to the main cushion (12) by means of at least one tear connection (26, 26a, 26b).

11. Frontal airbag according to one of the preceding claims, characterized in that the front area (14) of the main cushion comprises at least one opening (28) under the additional impact layer (22).

12. Frontal airbag according to one of the claims 4 to 10 and to claim 11 , characterized in that the supplemental element (20) is a part of an additional airbag (30) attached to the front area (14) of the main cushion (12) with the at least one opening (28) acting as an overflow opening between the gas space of the main cushion (12) and the gas space of the additional airbag (30). Frontal airbag according to claim 12, characterized in that the additional airbag further comprises two side panels (32a, 32b) being connected to the supplemental element (20).

Frontal airbag according to one of the preceding claims, characterized in that the height of the front area (14) of the main cushion (12) in a second direction (Z) perpendicular to the first direction (Y) exceeds the height of the additional impact layer (22).