WO2007145551A1

WO2007145551A1 - Anti-twist airbag in belt

Info

Publication number: WO2007145551A1
Application number: PCT/SE2006/000721
Authority: WO
Inventors: Thierry Jacqmarcq; Pascal Ouallet; Marianne Pobelle; Jérôme BRONNER; Jean Dourlens
Original assignee: Autoliv Development Ab
Priority date: 2006-06-16
Filing date: 2006-06-16
Publication date: 2007-12-21

Abstract

The present invention relates to a safety device for a vehicle seat, said safety device comprising a safety belt (2, 2' , 2'') , an airbag unit (1) provided along a portion of said safety belt, an anti-twist device (3) for preventing twisting of the airbag unit (1) and safety belt (2, 2' , 2'' ) at least in a vicinity of said airbag unit. The anti-twist device (3) comprises a series of mutually pivotable portions (4, 4', 4'') , which are connected to said airbag unit (1) and said safety belt (2, 2', 2'') , further said pivotable portions are relatively torsion stiff, said pivotable portions are mutually pivotable around axes which are directed in the plane of said safety belt (2, 2', 2'') and generally transversal to the length direction of said safety belt.

Description

ANTI-TWIST AIRBAG IN BELT

Technical Field

The present invention relates to a safety device for a vehicle seat, said safety device comprising a safety belt, an airbag unit provided along a portion of said safety belt, an anti-twist device for preventing twisting of the airbag unit (1) and safety belt at least in a vicinity of said airbag unit. The anti-twist device comprises a series of mutually pivotable portions, which are connected to said airbag unit and said safety belt, further said pivotable portions are relatively torsion stiff, said pivotable portions are mutually pivotable around axes which are directed in the plane of said safety belt (2, 2', 2'') and generally transversal to the length direction of said safety belt.

Background

At present time it is common to use airbags for automotive vehicles, these conventional airbags may be stowed in various positions of the vehicle, i.e. dashboard, steering wheel, seats, roof or pillars. It has recently been proposed also to provide airbags in the safety/seat belt, e.g. DE4232041 discloses an inflatable seat belt where part of the seat belt (the pelvis part) is provided with a bag, which bag retains unpacked with the belt in an inactivated state and in the event of a crash it is inflated and unfolded by gas.

The inflatable safety belt, compared to the conventional airbag, is preferably positioned directly against the occupant, i.e. it is all ready located in the area in which it is to exert its protective effect.

A drawback is that an inflatable seat belt may turn or twist around so that the bag portion is located in ^■ wrong position. It is important that the inflatable safety belt is positioned so that the inflatable portion can deploy/inflate to achieve a good protection for the occupant. The intension is that the bag portion should form a protective barrier to protect the occupant from hitting parts of the vehicle interior such as the dashboard, steering wheel or the back of the seat in front .

Summary of the Invention

It is an object of the present invention to provide a safety device that addresses the above-mentioned issues. This is achieved by a safety device according to claim 1. Preferred embodiments of the present invention are presented in the dependent claims .

According to a first aspect of the invention there is provided a safety device for a vehicle seat, said safety device comprising a safety belt, an airbag unit provided along a portion of said safety belt, an anti- twist device for preventing twisting of the airbag and safety belt at least in a vicinity of said airbag unit. The anti-twist device comprises a series of mutually pivotable portions, which are connected to said airbag unit and said safety belt, further said pivotable portions are relatively torsion stiff, said pivotable portions are mutually pivotable around axes which are directed in the plane of said safety belt and generally transversal to the length direction of said safety belt.

By torsion stiff is meant that the pivotable portions are relatively stiff in the transversal direction of the safety belt, providing a resistance against twisting of the structure. The pivotable portions are mutually pivotable around axes, i.e. movable relatively to each other substantially in bending around the body of the occupant. One objective of the anti-twist device is to prevent the airbag to twist so that the airbag would inflate or unfold in a direction towards the body of the occupant . The anti-twist device is constituted of a structure comprising pivotable portions at least in a vicinity of the airbag, for preventing the airbag to twist. The buckle of the safety belt need to be adjustable according to the size of the occupant.

Preferably, pivotable portions are arranged mutually locally spaced on at least one of the flat sides of the safety belt.

It is possible to control the movement of the anti- twist device with the design/shape of the mutual distance between the pivotable portions. Due to the fact that the pivotable portions are relatively torsion stiff, the structure will bend or deflect substantially only at the spaces or axes between the pivotable portions . These pivotable portions may be made of plastic or other suitable material .

Suitably, anti-twist device is arranged for providing generally only one degree of freedom for the motion of the airbag unit and safety belt. The definition of axes directed in the plane of the safety belt generally transversal to the length direction, means that when the pivotable portions will rotate around these axes, and the structure built up of the pivotable portions will bend generally with one degree of freedom, around the body of the occupant. It is advantageous if the anti-twist device is arranged for providing solely movability for forming the airbag unit and safety belt with a curved shape around the occupant. This fact provides safety and comfort for the occupant since the anti-twist device will prevent the airbag to deploy in an undesirable direction.

In a further aspect of the present invention the pivotable portions are constituted of circumferentially formed elements attached to the safety belt and further extending out from the plane of the safety belt forming an interior space inside the circumferentially formed elements . These circumferentially formed elements provides a protective, flexible, bendable cover inside which the airbag may be stored.

The circumferentially formed elements may further be said to form a cage providing an integrated casing for containing the airbag unit .

Further said safety belt may be provided constituting pivot joints between said pivotable portions. Due to the width of the safety belt and the fact that the pivotable portion does extent over generally the entire width of the belt, the belt may function as a pivot joint at a gap between adjacent pivot portions. When this gap is less than the width of the safety belt the twistability will be limited.

In a further aspect of the invention said pivotable portions may be interconnected by a membrane for providing bending flexibility. The membrane may be constituted of an elongated continuous element made of a flexible material.

In an alternative embodiment the pivotable portions are constituted of torsion stiff plates arranged mutually spaced and attached directly onto the safety belt. Since the torsion stiff plates are arranged mutually spaced they will constitute spaced members which provides a bending flexible structure . Preferably the distance between the pivotable portions is less than 0,75 times the width of the safety belt, more preferably is less than 0,5 times the width of the safety belt and most preferably is less than 0,25 times the width of the safety belt. This distance need to be large enough for the structure to achieve different desired curvature around different occupants. On the other hand the distance between the pivotable portions has an upper level over which the structure may be twisted an undesired amount. The distances between the stiff plates may be filled with a flexible material for providing a desired degree of freedom for the anti-twist device. This flexible material will admit the structure to bend but limit the movability in the torsion direction.

It is advantageous if the anti-twist device is provided for running free in the length direction in relation to said safety belt. If the anti-twist device is formed with an extension in the thickness direction of the safety belt, the length of the anti-twist device will vary at different thickness positions due to bending of the anti-twist device. Hence it is suitably if the safety belt is arranged free running in the length direction relatively to the anti-twist device.

Brief Description of the Drawings

Preferred embodiments of the present invention will in the following be described in more detail with reference to the accompanying exemplary drawings, in which:

Fig .1 shows a perspective view of a back seat occupant with a deployed safety belt airbag. Fig.2a depicts a perspective view of a anti-twist structure having the form of a cage.

Fig.2b depicts a perspective view of the anti-twist structure according to fig.2a in a bent condition.

Fig.2c shows a perspective view of a complete safety device according to the invention.

Fig.3a shows a side view of an alternative embodiment of the invention.

Fig.3b shows a top view of the embodiment in fig.3a.

Fig.4a shows a side view of further an embodiment of the invention.

Fig.4b shows a top view of the embodiment in fig.4a.

Description of Preferred Embodiments

Embodiments of the invention will be described in the following in more detail for exemplifying purposes and with reference to the accompanying drawings . With reference to fig 1 is shown a BIB (bag in belt) in a deployed condition at a rear passenger of a vehicle. For this kind of airbag 1 it is important to achieve a correct direction of deployment/inflation. It is further desirable to provide a safety belt 2 and airbag 1 that is comfortable for the occupant.

In fig 2a-c is shown a preferred embodiment of an anti-twist devise 3 according to the invention. The frame structure which takes the load and prevent the belt from twisting is shown in fig 2a-b. In this embodiment the frame structure of the anti-twist devise 3 is formed as a cage. Further there is provided a weakening line 6 which will break due to an expanding airbag stored inside the structure and provide a controlled expansion/deployment of the airbag. In this embodiment the anti-twist devise 3 is formed as a cage having pivotable portions 4 which are linked together by a connecting member 5. The pivotable portions are positioned with intermediate spaces providing bending flexibility to the structure. The circumferentially formed pivotable portions 4 provides the structure with torsion stiffness together with the connecting member 5.

In the embodiment shown in fig. 2 the safety belt is positioned opposite the connecting member 5, and the connecting member 5 is positioned away from the occupant. The safety belt may also be positioned in a vicinity of the connecting member 5, in this alternative embodiment the connecting member would be positioned towards the occupant and weakening lines would be positioned opposite the connecting member 5, one weakening line on each pivotable portion 4. Even though it is advantageous to position the safety belt close to the body of the occupant without layers of compressible material between the safety belt and the occupant, it is possible to position the safety belt somewhere in the middle of the structure. In the embodiment shown in fig 2b the spaces between the pivotable portions 4 will limit how much it is possible to bend the structure, the distance of the space between the pivotable portions 4 will decrease when bending the structure. At a certain bending the pivotable portions 4 will interfere and hence limit the bending.

If the structure is positioned the opposite way around, i.e. the connecting member 5 towards the occupant, the bending will not be limited by the pivotable portions 4 in the same way as described above.

In fig 2c is shown a complete safety devise according to the invention, a gas hose 8 is connected at the anchoring point 7 for supply of gas to the airbag

(BIB) . Further the safety belt 2 is positioned close to the occupant and the anti-twist device 3 is positioned mainly on the outer side of the safety belt. The safety device is formed with an outer casing 5' covering the safety device and presenting a soft, wear resistant, comfortable surface with thermal comfort to the occupant. This outer casing 5' is also provided with a split/break line 6' for a controlled expansion/deployment of the airbag. It is also possible to provide pivotable stiffening portions on both sides of the safety belt. In this case, if the safety belt is positioned in the middle of the anti-twist device 3 and acting as a neutral bending plane it is not necessary to provide movability between the safety belt 2 and the anti-twist device 3. Which might be the case in other embodiments .

The dimension of the gap between adjacent pivotable portions 4 will limit the bending and twisting of the anti-twist device 3. Further the properties of the material connecting the pivotable portions also affects the possibility to bend and twist the safety device. This connecting material might be constituted of the connecting member 5 and/or the safety belt.

The bending flexibility on the other band will mainly be limited by portions extending out from the belt (or connecting member 5) , which portions may interfere during bending and hence limit the bending. The gap between these portions may be covered, with a layer/fabric or similar protection, to avoid the risk for jamming/pinching of the occupant.

In an alternative embodiment of the present invention there are provided mutually spaced elements 4', 4'' which are attached directly onto the safety belt, by injection molding, gluing or by other suitable attachment as shown in fig. 3-4.

The anti-twist element 4', 4'' may also form an extra component applied to the belt as an extra layer.

The anti-twist element 4', A'' will prevent the belt from twisting when the belt is in use by the occupant. At the same time it will allow the belt to bend/flex in one direction over the body of the occupant. The anti-twist elements may consist of small plastic parts/plates linked to each other by a membrane or a band, which could be the safety belt 2', 2'' or other band. When linked together and attached to the belt the anti-twist elements 4', 4'' will make the safety device more torsion stiff. The anti-twist elements may be of other material than plastic, such as metal, textile, composite or other suitable material. The plastic parts may be of different sizes and shapes and positioned with different mutual distances. The anti-twist elements may be attached by different techniques such as; sewing, stitching, wrapping, gluing or other suitable method.

It is also possible to form the elements 4' with a z-profile as shown in fig 3a. This z-profile will make it possible to only bend the safety device towards the occupant, if trying to bend the safety device in the opposite direction the over lapping z-shape will prevent this.

Claims

1. A safety device for a vehicle seat, said safety device comprising a safety belt (2,2',2''), an airbag unit (1) provided along a portion of said safety belt, an anti- twist device (3) for preventing twisting of the airbag unit (1) and safety belt (2, 2', 2") at least in a vicinity of said airbag unit, c h a r a c t e r i z e d i n that said anti-twist device (3) comprises a series of mutually pivotable portions (4, 4', 4''), which are connected to said airbag unit (1) and said safety belt (2, 2' , 2' ' ) , further said pivotable portions are relatively torsion stiff, said pivotable portions are mutually pivotable around axes which are directed in the plane of said safety belt (2,2',2'') and generally transversal to the length direction of said safety belt.

2. A safety device according to claim 1, wherein said pivotable portions (4, 4 ' , A' ' ) are arranged mutually locally spaced on at least one of the flat sides of the safety belt (2,2' ,2" ) .

3. A safety device according to any of the preceding claims, wherein said anti-twist device (3) is arranged for providing generally only one degree of freedom for the motion of the airbag unit (1) and safety belt (2, 2' , 2") .

4. A safety device according to any of the preceding claims, wherein said anti-twist device (3) is arranged for providing solely movability for forming the airbag unit (1) and safety belt (2,2' ,2'') with a curved shape around the occupant.

5. A safety device according to any of the preceding claims, wherein said pivotable portions (4, 4', 4'') are constituted of circumferentially formed elements attached to the safety belt (2, 2', 2'') and further extending out from the plane of the safety belt forming an interior space inside the circumferentially formed elements.

6. A safety device according to claim 5, wherein said circumferentially formed elements forms a cage providing an integrated casing for containing the airbag unit (1) .

7. A safety device according to any of the preceding claims, wherein said safety belt (2, 2', 2'') constitutes pivot joints between said pivotable portions (4, 4', 4'').

8. A safety device according to any of the preceding claims, wherein said pivotable portions (4, 4', 4'') are interconnected by a membrane for providing bending flexibility.

9. A safety device according to any of the preceding claims, wherein said pivotable portions (4, 4', 4'') are constituted of torsion stiff plates arranged mutually spaced and attached directly onto the safety belt (2, 2', 2") .

10. A safety device according to claim 9, wherein said distance between the pivotable portions (4, 4', A'') preferably is less than 0,75 times the width of the safety belt, more preferably is less than 0,5 times the width of the safety belt and most preferably is less than 0,25 times the width of the safety belt (2, 2', 2").

11. A safety device according to any of the claims 9-10, wherein said distances between the stiff plates are filled with a flexible material for providing a desired degree of freedom for the anti-twist device (3) .

12. A safety device according to any of the claims 9-11, wherein said anti-twist device (3) is provided for running free in the length direction in relation to said safety belt (2,2' ,2" ) .