WO2008130281A1

WO2008130281A1 - A safety arrangement

Info

Publication number: WO2008130281A1
Application number: PCT/SE2007/000371
Authority: WO
Inventors: Nicolas Dubois; Sebastien Cornec
Original assignee: Autoliv Development Ab
Priority date: 2007-04-19
Filing date: 2007-04-19
Publication date: 2008-10-30

Abstract

A safety arrangement (1) to be mounted to part of a vehicle. The safety arrangement (1) comprises an air-bag module (7) and a movement device (12,13). The movement device (12,13) is configured to move the air-bag module (7) from a first position to a second position such that the air-bag module (7) may be moved closer to an occupant of the motor vehicle.

Description

Title: "A Safety Arrangement"

Description of Invention

THE PRESENT INVENTION relates to a safety arrangement, and more particularly relates to a safety arrangement to be installed in a motor vehicle to protect an occupant of the vehicle in the event that a crash situation occurs.

A driver's side air-bag module is usually mounted to the steering wheel of a motor vehicle, with the air-bag module being configured to inflate an air-bag in front of the driver of the vehicle to protect the driver in the event that a crash situation occurs. During a crash situation the driver will be moved relative to the vehicle by forces arising from the crash. The driver moves against the inflated air-bag and the inflated air-bag acts as a cushion which is intended to decelerate the driver gently to minimise the risk of the driver being injured in the crash. It is desirable for the inflated air-bag to couple with the driver before the driver is moved by the forces arising from the crash situation so that the occupant can be decelerated in a controlled and gentle manner.

It has been proposed previously to actuate an air-bag module in response to an anticipated crash situation so that an air-bag can be inflated before the crash occurs and couple with an occupant before the occupant is moved by the forces arising during the crash. In order to achieve this "early coupling" it has been proposed previously to provide an air-bag which has a larger volume than a standard air-bag. The air-bag has a larger volume than normal so that the air-bag can fill the large space in front of the occupant which usually exists before the occupant has not yet been moved by forces from the crash situation. The larger than normal air-bag allows for early coupling with the occupant and hence maximises the chances of decelerating the occupant in a controlled and gentle manner when the crash situation actually occurs. However, large air- bags of this type are expensive to manufacture and are heavy because of the large amount of material needed to make up the air-bag. In addition to this, a larger than normal inflator is needed to generate the large volume of gas to inflate the air-bag and the large inflator is expensive and heavy.

The present invention seeks to provide an improved safety arrangement.

According to one aspect of the present invention, there is provided a safety arrangement to be mounted to part of a motor vehicle, the safety arrangement comprising an air-bag module which incorporates an air-bag, the air-bag being configured to be inflated by a source of gas in response to an actuation signal, characterised in that the arrangement further comprises a movement device which is configured to move the air-bag module in response to a movement signal from a first position to a second position such that the air-bag module may be moved closer to an occupant of the motor vehicle.

Preferably the safety arrangement further comprises a pre-crash sensor which is configured to sense an anticipated crash situation and to generate the movement signal in response to the sensed anticipated crash situation.

In one embodiment the pre-crash sensor is a radar.

Preferably the pre-crash sensor is configured to generate the movement signal substantially 50ms or more before the crash situation is due to occur.

Conveniently the safety arrangement further comprises a control unit which is configured to generate the actuation signal after a predetermined length of time has elapsed following the start of a crash situation. Advantageously the predetermined length of time is substantially 40ms.

In one embodiment the control unit calculates the predetermined length of time from the time at which the anticipated crash sensed by the pre-crash sensor is due to occur.

In another embodiment the safety arrangement further comprises a crash sensor which transmits a crash signal to the control unit in the event that a crash is sensed, the control unit being configured to generate the actuation signal after a predetermined length of time has elapsed after it has received the crash signal.

Preferably the control unit is configured to generate the actuation signal in response to a crash signal produced by the crash sensor before a movement signal has been generated and to prevent subsequent generation of the movement signal.

Conveniently the movement device comprises an elongate extendible sleeve which is configured to define a reduced length and an extended length, the sleeve being connected to the air-bag module and configured to define the reduced length when the air-bag module is in the first position, the sleeve being configured to extend to the extended length in response to the movement signal to move the air-bag module from the first position to the second position.

In one embodiment the sleeve is of a deformable material which is folded when the sleeve defines the reduced length.

Preferably the diameter of the sleeve is substantially constant along the length of the sleeve when the length of the sleeve defines the extended length. Conveniently the internal volume of the sleeve when the sleeve defines the extended length is substantially 750 cm³.

Advantageously the sleeve is of coated fabric.

In one embodiment at least part of the sleeve is surrounded by a plastic sheath.

In another embodiment the sleeve is defined by a plurality of smaller telescoped sleeves.

Preferably the movement device further comprises a gas generator which is actuable in response to the movement signal to inject gas into the sleeve to cause the sleeve to extend from the reduced length to the extended length.

In a further embodiment the sleeve is provided with a vent which is configured to vent gas from within the sleeve.

Preferably the vent is a controllable vent which is initially closed, but which may be opened in response to a control signal after a predetermined length of time has elapsed following generation of the movement signal.

Conveniently the sleeve may be reset from the extended length to the reduced length after the movement device has moved the air-bag module.

Advantageously the sleeve is configured to reduce in length from its extended length towards its reduced length in response to a force exerted by an occupant moving against the safety arrangement during a crash situation. Preferably the sleeve is configured to dissipate energy from the occupant as the sleeve reduces in length.

In one embodiment the air-bag is provided with at least one tear seam.

Preferably the air-bag module further comprises a housing in which the air-bag is stored and a cover which covers the housing.

Conveniently the movement device is configured to move the air-bag module over a distance of substantially 15 cm from its first position.

Advantageously the safety arrangement further comprises a position sensor which senses the position of an occupant relative to the air-bag module, the sensor being configured to produce a stop signal to prevent actuation of the movement device in the event that the occupant is less than a predetermined distance from the air-bag module.

In one embodiment the safety arrangement is mounted to a steering wheel.

In another embodiment the safety arrangement is configured to be mounted to part of a dashboard of a motor vehicle.

According to another aspect of the present invention there is provided a motor vehicle incorporating the safety arrangement defined in any one of the claims hereinafter.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic sectional view of a steering wheel which is provided with a safety arrangement in accordance with a preferred embodiment of the invention, with the arrangement in a normal unactuated condition,

Figure 2 is a view corresponding to Figure 1 after actuation of a movement device,

Figure 3 is a view corresponding to Figure 1 after inflation of an air-bag,

Figure 4 is a diagrammatic sectional view of part of a movement device of a further embodiment of the invention, and

Figure 5 is a diagrammatic sectional view of part of a movement device of a safety arrangement of a yet further embodiment of the invention.

Referring initially to Figure 1 of the accompanying drawings, a safety arrangement 1 is mounted to the hub 2 of a steering wheel 3. The hub 2 defines an inner chamber 4 which receives part of the safety arrangement 1. Spokes 5 extend radially outwardly from the hub 2 to support the rim 6 of the steering wheel 3.

The safety arrangement 1 comprises an air-bag module 7. The air-bag module 7 incorporates a housing 8 which houses an air-bag 9 (only visible in Figure 3). A cover 10 closes the housing 8 to retain the air-bag 9 within the housing 8. A source of gas in the form of a gas generator 11 is attached to the housing 8 and configured to inflate the air-bag 9 in response to an actuation signal.

The underside of the air-bag module 7 is attached to one end of an extendible elongate sleeve 12 which is of a deformable material. In this preferred embodiment the sleeve 12 is of coated fabric which is substantially impermeable to gas. The sleeve 12 is generally frustoconical in shape when in its unfolded extended configuration as shown in Figure 3. As will become clear from the description below, the sleeve 12 acts as an expandable element which defines part of a movement device for moving the air-bag module 7.

When the safety arrangement 1 is in a normal, unactuated, condition the sleeve 12 is folded such that the sleeve defines a reduced length which is shorter than when the sleeve 12 is unfolded. When the sleeve 12 is folded to define the reduced length the sleeve 12 retains the air-bag module 7 in a first position in which the air-bag module 7 is directly adjacent the hub 2 of the steering wheel 3, as seen in Figure 1.

The other end of the sleeve 12 is attached to the hub 2 so that when the sleeve 12 is folded to define the reduced length the sleeve 12 is positioned within the chamber 4 of the hub 2, as seen in Figure 1. The sleeve 12 is connected to the hub 2 and the air-bag module 7 with a substantially gas-tight seal. An inflator 13 which defines another part of the movement device is mounted to the hub 2. The inflator 13 is configured to inject gas into the interior of the sleeve 12 in response to a movement signal. In this preferred embodiment the inflator 13 is a mini gas generator, but it is to be appreciated that in other embodiments the inflator 13 may be a different source of gas, such as a squib.

The safety arrangement 1 of this preferred embodiment incorporates a control unit 14 which is connected to receive signals from a pre-crash sensor 15 and a crash sensor 16, and a position sensor 17.

In this preferred embodiment the pre-crash sensor 15 is a radar which is configured to sense an anticipated crash situation and to generate a movement signal around 50 ms before the crash is due to occur. The crash sensor 16 generates a crash signal at the moment when the crash sensor 16 senses that a crash situation is starting to occur.

In the event that the pre-crash sensor 15 senses an anticipated crash situation the pre-crash sensor 15 generates the movement signal and transmits the movement signal to the control unit 14. The control unit 14 communicates the movement signal to the inflator 13 and the inflator 13 is actuated in response to the movement signal. When the inflator 13 is actuated the inflator 13 injects gas into the interior of the sleeve 12. The pressure of gas within the interior of the sleeve 12 causes the sleeve 12 to extend from its reduced length to its maximum extended length, as seen in Figure 2. As the sleeve 12 extends, the sleeve 12 moves the air-bag module 7 from the first position to a second position in which the air-bag module 7 is positioned away from the hub 2 of the steering wheel 3 and closer to an occupant who is seated in front of the steering wheel 3. In this preferred embodiment the sleeve 12 moves the air- bag module 7 a distance of 15 cm from its first position to its second position. The air-bag module 7 is thus moved closer to an occupant of the vehicle before the air-bag 9 is inflated.

When the crash sensor 16 senses that the crash situation actually starts to occur, the crash sensor 16 sends a crash signal to the control unit 14. In response to the crash signal, the control unit 14 generates an actuation signal which is transmitted to the gas generator 11. In response to the actuation signal, the gas generator 11 injects gas into the interior of the air-bag 9 to inflate the air-bag 9, as seen in Figure 3.

Since the air-bag module 7 was moved closer to the occupant before the air- bag module was actuated the distance between the air-bag module 7 and the occupant was reduced and hence the space to be filled by the air-bag 9 to couple with the occupant was also reduced. Consequently, early coupling with the occupant can be achieved using an air-bag of a standard size. There is thus no longer the need for a larger than normal air-bag to achieve early coupling with an occupant.

As an occupant of the vehicle moves against the inflated air-bag 9 due to forces arising from the crash the sleeve 12 deforms and acts as a load limiter to absorb energy from the occupant in conjunction with the air-bag 9.

After actuation of the safety arrangement the movement device can be reset by folding the sleeve 12 back to its initial position within the chamber 4 in the hub 2 to allow the sleeve 12 to be reused.

The position sensor 17 is configured to sense the position of an occupant of the vehicle relative to the air-bag module 7. The position sensor 17 preferably tales the form of a piezoelectric sensor, but takes any other convenient form, and is configured to transmit a stop signal to the control unit 14 in the event that an occupant of the vehicle is "out of position", that is to say less than a predetermined distance from the air-bag module 7. Upon receipt of the stop signal, the control unit 14 prevents actuation of the movement device by stopping the movement signal from being communicated from the pre-crash sensor 15 to the inflator 13. The movement device is thus prevented from moving the air-bag module 7 to a position which is too close to the out-of- position occupant for the air-bag to be inflated safely.

If the air-bag module 7 remains in the first position following detection of an out-of-position occupant and the crash sensor 16 generates a crash signal, then if the control unit 14 determines that it is appropriate, the control unit 14 transmits the actuation signal to the gas generator 11 to inflate the air-bag 9. The air-bag 9 is inflated in front of the occupant but, because the air-bag module 7 has not been moved by the movement device, the air-bag 9 is more likely to be at a safe distance from the occupant to allow safe deployment of the air-bag 9.

The air-bag 9 is provided with at least one tear seam 18 which is only configured to rupture if the air-bag 9 is not obstructed by the rim 6 of the steering wheel 3 as the air-bag 9 inflates. The air-bag 9 is not obstructed by the rim 6 if the air-bag 9 is inflated after the air-bag module 7 has been moved to the second position. If the air-bag module 7 is actuated when in the first position, for instance following detection of an out-of-position occupant, then the air-bag module 7 is close to the rim 6 and inflation of the air-bag 9 is blocked by the rim 6 so the tear seams 18 do not rupture. The tear seams 18 thus allow the shape of the inflating air-bag 9 to be adapted in dependence upon whether or not the movement device has moved the air-bag module 7 from the first position to the second position.

Whilst the sleeve 12 of the preferred embodiment described above is generally frustoconical in shape, in a further embodiment of the invention the sleeve 12 is substantially cylindrical in shape, as shown in Figure 4. The sides of the cylindrical sleeve 12 are provided with corrugations 19 which allow the sleeve 12 to be compressed or extended easily. The sleeve 12 of this further embodiment has a generally constant diameter along its length and this constant diameter helps to keep the air-bag module 7 stable when the air-bag module 7 is being moved to the second position by the sleeve 12.

Whilst in the embodiments described above, the sleeve 12 is of coated fabric, in other embodiments of the invention the sleeve 12 may be of a different deformable material, such as metal or plastic.

In some embodiments of the invention at least part of the sleeve 12 is surrounded by a plastic sheath which may, for instance, be of polyethylene. In the embodiments described above the internal volume of the sleeve 12 when the sleeve defines its maximum extended length is substantially 750 cm³.

Referring now to Figure 5, in a yet further embodiment of the invention, the sleeve 12 is defined by a plurality of smaller telescoped sleeves 20. Each of the telescoped sleeves defines a lower lip 21 and an upper lip 22. O-ring seals 23 are provided between the lips 21 ,22 of adjacent telescoped sleeves 20 so that there is a substantially gas-tight seal between the telescoped sleeves 20. The O-ring seals 23 each undergo a rolling movement around the edge of one of the telescoped sleeves 20 to permit the telescoped sleeves to move relative to one another so that the sleeve 12 can move from a reduced length to an extended length, as shown in Figure 5. It will be appreciated that the telescoped sleeves 20 of this yet further embodiment are moved apart from one another by forces from gas injected by the inflator 13 into the interior of the sleeve 12 so that the sleeve 12 can extend to its extended length in a similar manner to the embodiments described above.

In embodiments of the invention the sleeve 12 may be provided with a vent so that gas can be vented from the sleeve 12 after the sleeve 12 has been extended. The vent allows gas to be vented in a controlled manner from the sleeve 12 as an occupant moves against the air-bag 9 so that the sleeve 12 provides a cushioning effect in conjunction with the air-bag 9 to decelerate the occupant. The vent may be a controllable vent which is initially closed, but which may be opened in response to a control signal after a predetermined length of time has elapsed following generation of a movement signal by the control unit 14.

Whilst the safety arrangement of the embodiments described above is a steering wheel mounted safety arrangement, it is to be appreciated that the safety arrangement may be mounted to a different part of a motor vehicle. For instance, the safety arrangement may be mounted to part of a dashboard of a motor vehicle to offer protection to a passenger in the vehicle. Indeed, the safety arrangement can be mounted to any part of a motor vehicle where it is desirable for early air-bag coupling.

In the embodiments described above, it is to be appreciated that if the movement device is actuated to move the air-bag module 7 from the first position to the second position and no accident situation occurs, the movement device can be replaced independently of the air-bag module 7 so that the costs of replacing the unactuated air-bag module 7 can be avoided.

It is to be appreciated that embodiments of the invention may incorporate a greater or less number of sensors than the embodiments described above. For instance, in one embodiment there is no crash sensor and in this embodiment the actuation signal to actuate inflation of the air-bag 9 is generated by the control unit 14 after a predetermined time has elapsed following the detection of an anticipated crash situation.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

Claims

1. A safety arrangement (1) to be mounted to part of a motor vehicle, the safety arrangement (1) comprising: an air-bag module (7) which incorporates an air-bag (9), the air-bag (9) being configured to be inflated by a source of gas (11) in response to an actuation signal, characterised in that the arrangement (1 ) further comprises; a movement device (12,13) which is configured to move the air-bag module (7) in response to a movement signal from a first position to a second position such that the air-bag module (7) may be moved closer to an occupant of the motor vehicle.

2. A safety arrangement according to claim 1 , wherein the safety arrangement (1 ) further comprises a pre-crash sensor (15) which is configured to sense an anticipated crash situation and to generate the movement signal in response to the sensed anticipated crash situation.

3. A safety arrangement according to claim 3, wherein the pre-crash sensor (15) is a radar.

4. A safety arrangement according to claim 2 or claim 3, wherein the pre-crash sensor (15) is configured to generate the movement signal substantially 50ms or more before the crash situation is due to occur.

5. A safety arrangement according to any one of the preceding claims, wherein the safety arrangement (1) further comprises a control unit (14) which is configured to generate the actuation signal after a predetermined length of time has elapsed following the start of a crash situation.

6. A safety arrangement according to claim 5, wherein the predetermined length of time is substantially 40ms.

7. A safety arrangement according to claim 5 or claim 6 as dependent on any one of claims 2 to 4, wherein the control unit (14) calculates the predetermined length of time from the time at which the anticipated crash sensed by the pre-crash sensor (15) is due to occur.

8. A safety arrangement according to claim 5 or claim 6, wherein the safety arrangement (1) further comprises a crash sensor (16) which transmits a crash signal to the control unit (14) in the event that a crash is sensed, the control unit (14) being configured to generate the actuation signal after a predetermined length of time has elapsed after it has received the crash signal.

9. A safety arrangement according to claim 8, wherein the control unit (14) is configured to generate the actuation signal in response to a crash signal produced by the crash sensor (16) before a movement signal has been generated and to prevent subsequent generation of the movement signal.

10. A safety arrangement according to any one of the preceding claims, wherein the movement device (12,13) comprises an elongate extendible sleeve (12) which is configured to define a reduced length and an extended length, the sleeve (12) being connected to the air-bag module (7) and configured to define the reduced length when the air-bag module (7) is in the first position, the sleeve (12) being configured to extend to the extended length in response to the movement signal to move the air-bag module (7) from the first position to the second position.

11. A safety arrangement according to claim 10, wherein the sleeve (12) is of a deformable material which is folded when the sleeve (12) defines the reduced length.

12. A safety arrangement according to claim 11 , wherein the diameter of the sleeve (12) is substantially constant along the length of the sleeve (12) when the length of the sleeve (12) defines the extended length.

13. A safety arrangement according to claim 11 or claim 12, wherein the internal volume of the sleeve (12) when the sleeve (12) defines the extended length is substantially 750 cm³.

14. A safety arrangement according to any one of claims 11 to 13, wherein the sleeve (12) is of coated fabric.

15. A safety arrangement according to any one of claims 11 to 14, wherein at least part of the sleeve (12) is surrounded by a plastic sheath.

16. A safety arrangement according to claim 10, wherein the sleeve (12) is defined by a plurality of smaller telescoped sleeves (20).

17. A safety arrangement according to any one of claims 10 to 16, wherein the movement device (12,13) further comprises a gas generator (13) which is actuable in response to the movement signal to inject gas into the sleeve (12) to cause the sleeve (12) to extend from the reduced length to the extended length.

18. A safety arrangement according to any one of claims 10 to 17, wherein the sleeve (12) is provided with a vent which is configured to vent gas from within the sleeve (12).

19. A safety arrangement according to claim 18, wherein the vent is a controllable vent which is initially closed, but which may be opened in response to a control signal after a predetermined length of time has elapsed following generation of the movement signal.

20. A safety arrangement according to any one of claims 10 to 19, wherein the sleeve (12) may be reset from the extended length to the reduced length after the movement device (12,13) has moved the air-bag module (7).

21. A safety arrangement according to any one of claims 10 to 20, wherein the sleeve (12) is configured to reduce in length from its extended length towards its reduced length in response to a force exerted by an occupant moving against the safety arrangement (1 ) during a crash situation.

22. A safety arrangement according to claim 21 , wherein the sleeve (12) is configured to dissipate energy from the occupant as the sleeve (12) reduces in length.

23. A safety arrangement according to any one of the preceding claims, wherein the air-bag (9) is provided with at least one tear seam (18).

24. A safety arrangement according to any one of the preceding claims, wherein the air-bag module (7) further comprises a housing (8) in which the air-bag (9) is stored and a cover (10) which covers the housing (8).

25. A safety arrangement according to any one of the preceding claims, wherein the movement device (12,13) is configured to move the air-bag module (7) over a distance of substantially 15 cm from its first position.

26. A safety arrangement according to any one of the preceding claims, wherein the safety arrangement (1 ) further comprises a position sensor (17) which senses the position of an occupant relative to the air-bag module (7), the sensor (17) being configured to produce a stop signal to prevent actuation of the movement device (12,13) in the event that the occupant is less than a predetermined distance from the air-bag module (7).

27. A safety arrangement according to any one of the preceding claims mounted to a steering wheel (3).

28. A safety arrangement according to any one of claims 1 to 26, wherein the safety arrangement (1) is configured to be mounted to part of a dashboard of a motor vehicle.

29. A motor vehicle incorporating the safety arrangement (1) of any one of the preceding claims.