WO2004074050A1

WO2004074050A1 - An air-bag unit

Info

Publication number: WO2004074050A1
Application number: PCT/SE2004/000043
Authority: WO
Inventors: Ola BOSTRÖM; Yngve Håland; Leif Ennerdal.
Original assignee: Autoliv Development Ab
Priority date: 2003-02-21
Filing date: 2004-01-16
Publication date: 2004-09-02
Also published as: GB2398546A; GB0304012D0; GB2398546B

Abstract

An air-bag unit is disclosed which is mounted to the inboard side of a vehicle seat (1). The air-bag unit comprises an inflatable air-bag (15) connected to an inflator (14) which is actuable to inflate the air-bag (15). The air-bag unit also comprises a support element (18). The air-bag (15) is configured to provide lateral protection to at least the thorax (7) of an occupant (4) of the seat (1) and the support element (18) is moveable upon actuation of the air-bag unit from an initial position to an operative position. The support element (18) is configured to extend inboard of the inflated air-bag (15) when in its operative position so as to provide lateral support to at least part of the inflated air-bag (15).

Description

"AN AIR-BAG UNIT"

THE PRESENT INVENTION relates to an air-bag unit, and more particularly relates to an air-bag unit mounted to the inboard side of a vehicle seat.

It is known to provide motor vehicle seats with one or more air-bags configured so that the air-bag may be inflated in a side impact crash situation, in order to provide lateral protection to an occupant of the seat. A typical type of such an arrangement comprises an air-bag module mounted to the outboard side of the back-rest of a vehicle seat, the air-bag module being arranged so that the air-bag is inflated in a forwards direction relative to the back-rest, such that the air-bag is deployed to the outboard side of an occupant of the seat, so that the inflated air-bag extends between the occupant and the side panel, door or window of the motor vehicle. This type of "side air-bag" arrangement is intended to provide lateral protection to an occupant of the seat in the event of a side impact.

However, it will be appreciated that because the above-described side air-bag arrangement is provided on the outboard side of the vehicle seat, then it only provides effective lateral protection to an occupant of the seat in the event that the impact occurs on the same side of the vehicle to which the seat is mounted. If a side impact were to occur from the opposite side of the vehicle (i.e. the side remote from the vehicle seat), then the outboard side air-bag arrangement would not provide effective protection to the occupant of the seat whose body would tend to move towards the impact-side of the motor vehicle under its inertia.

It has therefore been proposed previously to provide the two spaced- apart front seats of a motor vehicle with respective inboard side air-bag arrangements comprising an air-bag unit mounted to the inboard side of each seat. One such type of arrangement is disclosed in GB2309440A. This arrangement relies upon the actuation of both inboard side air-bags in the event of a side impact from either side of the motor vehicle so that the two bags support one another, when inflated, in a lateral direction across the motor vehicle to provide lateral protection to the seat occupant located on the impact side of the motor vehicle. It will therefore be appreciated that this type of arrangement will not provide adequate lateral support to an occupant of one of the seats unless both air-bags are actuated together. It is therefore desirable to provide a "self-supporting" inboard side air-bag arrangement.

The present invention therefore seeks to provide an improved air-bag unit mounted to the inboard side of a vehicle seat.

According to the present invention, there is provided an air-bag unit mounted to the inboard side of a vehicle seat, the air-bag unit comprising: an inflatable air-bag connected to an inflator actuable to inflate the air-bag, and a support element; the air-bag being configured to provide lateral protection to at least the thorax of an occupant of the seat, and the support element being moveable upon actuation of the air-bag unit from an initial position to an operative position, the support element being configured to extend inboard of the inflated air-bag when in said operative position so as to provide lateral support to at least part of the inflated air-bag.

Preferably, said support element is resiliently deformable and configured, when in said operative position, to yield under a force exerted thereon by the weight of an occupant of the seat in a crash, thereby absorbing energy.

Advantageously, the air-bag unit is mounted to the backrest of the vehicle seat, and the inflator is positioned to direct gas into the air-bag in a generally forwards direction relative to the back-rest, said support element being configured to move from said initial position to said operative position in a generally forwards direction relative to said back-rest.

Conveniently, the air-bag unit further comprises a housing in which said air-bag and said inflator are provided, wherein said support element forms part of the housing.

Preferably, said support element is mounted for pivotal movement from said initial position to said operative position.

Advantageously, said support element is configured to deform during movement from said initial position to said operative position.

Conveniently, said support element is moved from said initial position towards said operative position by engagement with the air-bag during inflation of the air-bag. Preferably, said support element is slidably mounted for slideable movement from said initial position to said operative position.

Advantageously, said support element is resiliently biased towards said operative position.

Conveniently, said resilient bias is provided by a spring.

Preferably, the air-bag unit is configured to direct a flow of gas from the inflator towards the support element such that said support element is urged from said initial position towards said operative position by said flow of gas.

Advantageously, the air-bag unit is mounted to the vehicle seat so as to be at least partially covered by upholstery.

Conveniently, configured to direct a flow of gas from the inflator towards the support element such that said support element is urged from said initial position towards said operative position by said flow of gas.

Preferably, said support element has a dimension (a), in a direction substantially peφendicular to the axis of the back-rest of the seat, of between 70mm and 200mm.

Advantageously, said support element has a dimension (b), in a direction substantially parallel to the axis of the back-rest of the seat, of between 100mm and 250mm.

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

FIGURE 1 is a schematic side-view from the inboard side of a vehicle seat, illustrating a deployed air-bag generally in accordance with the present invention;

FIGURE 2 is a view corresponding generally to that of Figure 1, but illustrating a variant of the air-bag illustrated in Figure 1.

FIGURE 3 is a transverse cross-sectional view taken through a seat having a air-bag unit of a first embodiment of the present invention mounted to the inboard side of the seat;

FIGURE 4 is an enlarged cross-sectional view of part of the air-bag unit illustrated in Figure 3;

FIGURE 5 is a view corresponding generally to that of Figure 3, but illustrating the air-bag unit in a deployed condition;

FIGURE 6 is an enlarged cross-sectional view of part of the deployed air-bag unit illustrated in Figure 5;

FIGURE 7 is a transverse cross-sectional view through an air-bag unit in accordance with another embodiment of the present invention. FIGURE 8 is a view corresponding generally to that of Figure 7 but illustrating the alternative air-bag unit in a deployed condition;

FIGURE 9 is a transverse sectional view through the inboard part of a vehicle seat showing another alternative type of air-bag unit mounted to the seat; FIGURE 10 is a view corresponding generally to that of Figure 9, but illustrating the air-bag unit at an instant during deployment of the air-bag;

FIGURE 11 is a transverse cross-sectional view through another embodiment of the air-bag unit, showing the air-bag unit mounted to the inboard side of a vehicle seat; and FIGURE 12 is a view corresponding generally to that of Figure 11, but illustrating the air-bag unit at an instant during deployment of the air-bag.

Referring initially to Figure 1, there is illustrated schematically a vehicle seat 1 having a squab 2 and a back-rest 3 which extends upwardly and slightly rearwardly from the rear part of the squab 2. The seat 1 is illustrated supporting an occupant 4 in a normal sitting position.

The vehicle seat 1 is provided with an air-bag unit indicated generally at 5, the air-bag unit 5 being mounted to the inboard side of the back-rest 3. The air-bag unit 5 is illustrated in a deployed condition and it will be seen that the air-bag unit 5, in this condition, comprises an inflated air-bag 6 which extends forwardly from the back-rest 3, so as to pass to the inboard side of the thorax 7 of the seat occupant 4. The air-bag unit 5 also comprises a support element 8 which is shown in an actuated condition in which it also extends forwardly from the back-rest 3 on an inboard side of the inflated air-bag 6 such that the air-bag 6 extends between the support element 8 and the thorax 7 of the seat occupant 4. The support element 8, in this deployed condition, serves to provide lateral support to the inflated air-bag 6 so as to hold it in a position effective to provide lateral protection to the thorax 7 of the seat occupant 4 in the event of a side impact. The air-bag 6 provides protection to the occupant by supporting his or her thorax during a side impact, and also, optionally, providing an energy absoφtion function.

Figure 2 illustrates a variant of the arrangement illustrated in Figure 1 in which the inflated air-bag 6 has a slightly different configuration. In the arrangement of Figure 2, the air-bag 6 is shaped, when substantially fully inflated, so as to extend forwardly from the back-rest 3 and also to extend upwardly from the region of the back-rest 3 to which the air-bag unit 5 is mounted so that the inflated air-bag provides lateral protection to the head 9 of the seat occupant 4 as well as to the thorax 7. It will be seen that the support element 8, illustrated in Figure 2 in its deployed condition, is substantially identical to the support element illustrated in the Figure 1 arrangement and so serves to provide lateral support to the inflated air-bag 6 in the region of the thorax 7 of the occupant 4.

Turning now to consider Figure 3, the air-bag unit 5 comprises a housing 10 which is substantially rigidly secured via any convenient means (such as, for example, bolts or screws) to an internal frame 11 provided within the back-rest 3 of the seat 1. For the purposes of illustration, the vehicle seat 3 to which the housing 10 is secured, is illustrated adjacent another vehicle seat 12. The vehicle seats 1, 12 represent the two front seats of a motor vehicle having a conventional seat configuration. It will therefore be understood that the air-bag unit 10 is secured to the "inboard" side of the vehicle seat 1, and is hence located on the opposite side of the vehicle seat 1 to the side 13 panel of the motor vehicle adjacent the seat 1. The other seat 12 could also be provided with a similar air-bag arrangement 5, mounted to its inboard side, although this is not illustrated.

Within the housing 10 of the air-bag unit 5, there is mounted an inflator 14, such as, for example, a generally conventional gas generator. The inflator 14 is fluidly connected to a folded or otherwise packed inflatable air-bag 15 and is actuable upon receipt of an appropriate signal indicative of a crash situation, to direct a volume of gas into the interior of the air-bag 15, thereby inflating the air-bag 15 in a direction generally towards the front of the motor vehicle. In the particular arrangement illustrated in Figure 3, the air-bag 15 is shown to be zigzag folded into its packed condition in which it is completely located within the initially closed housing 10. However, it should be appreciated that the air-bag 15 could be packed in any other convenient way such as, for example, by being rolled or packed via a combination of folding and rolling.

It is envisaged that the housing 10 will be moulded from plastics material although the air-bag housing 10 could be made from any other convenient materials.

The housing 10 has a generally rectangular cross-section and comprises a pair of opposed side walls 16, 17. In the initial, un-deployed condition illustrated in Figure 3, the front part of the housing 10 is closed by a moveable support element 18 which takes the form of a door pivotally mounted to the forwardmost edge of the inboard side wall 17. The support element 18, in its initial closed position illustrated in Figure 3, extends from the forwardmost edge of the inboard side wall 17 to the forwardmost edge of the outboard side wall 16 and is releasably connected to the forwardmost edge of the outboard side wall 16. This releasable connection between the support element 18 and the outboard side wall 16 can, for example, be via a frangible part of the moulded housing 10.

Figure 4 illustrates in more detail the pivotal connection between the support element 18 and the forwardmost edge of the inboard side wall 17. A pair of metal plates 20, 21 are provided such that one of the metal plates 20 is secured, for example by way of conventional bolts 22 to the support element 18, and the other metal plate 21 is similarly secured to the forwardmost part of the inboard side wall 17.

Turning now to consider Figure 5, the air-bag unit 5 is illustrated in a condition in which the inflator 14 has been actuated, thereby inflating the air- bag 15. As the air-bag 15 inflates from its initially packed configuration illustrated in Figure 3, it extends generally forwardly relative to the seat 1, thereby urging the moveable support element 18 away from the forwardmost edge of the outboard side wall 16, breaking the frangible connection therebetween. As the air-bag 15 continues to inflate, the moveable support 18 is forced to rotate forwardly about the inboard wall 17 until it adopts a position substantially as shown in Figure 5, in which it is aligned with and extends generally forwardly from the inboard side wall 17 of the housing 10.

Figure 6 illustrates in greater detail the configuration of the pivotal connection 19 between the element 18 and the side wall 17 when the moveable support element 18 adopts the position illustrated in Figure 5. It will be seen from Figure 6 that in this position, the rearmost edge of the metal plate 20 secured to the moveable support element 18 engages the forwardmost edge of the metal plate 21 secured to the inboard side wall 17 of the housing 10. This engagement between the two metal plates 20, 21 prevents further unrestricted pivotal movement of the support element 18 relative to the side wall 17, past its forwardly-extending operative position illustrated in Figure 5.

It should therefore be appreciated that when the moveable element 18 is moved forwardly from its initial position illustrated in Figure 3 to its operative position illustrated in Figure 5, it extends generally forwardly relative to the seat 1 and inboard of the inflated air-bag 15, thereby providing lateral support to the inflated air-bag 15. This lateral support serves to hold the inflated air-bag 15 in a position effective to provide lateral protection to the occupant 4 by supporting the occupant's upper body and also, optionally, absorbing energy due to the occupant's inertia. However, the connection 19 between the support element 18 and the side wall 17 of the housing 10 is configured to be resiliently deformable so that the support element 18 can yield slightly under an inwardly- directed force exerted on it by the weight of an occupant of the seat 1 in the event of a crash, thereby absorbing energy from the occupant's movement inboards towards the centre of the car. This is provided via deformation of the two metal plates 20, 21 as the generally forwardly-extending support element 18 is urged further inboard under the weight of the occupant's body, from its position illustrated in Figure 5.

It will therefore be seen that the support element 18 of the above- described arrangement is provided in an initial position prior to actuation of the air-bag unit 5 and, upon actuation of the air-bag unit 5, is caused to move towards an operative position as illustrated in Figure 5 in which the support element 18 provides lateral support to the inflated air-bag 15.

Figure 7 illustrates an alternative configuration of the air-bag unit 5. In this arrangement, the air-bag unit 5 again comprises a housing 10 which is preferably moulded from plastics material and comprises an outboard forwardly-extending side wall 16 and an inboard forwardly-extending side wall 17. The housing 10 is again closed by a moveable support element 18. The support element 18 extends between a frangible connection 23 with the forwardmost part of the outboard side wall 16, and the forwardmost edge of the inboard side wall 17. In this arrangement, the support element 18 is moulded integrally with the side wall 17.

Located inside the housing 10 is a resiliently deformable metal bracket

24 which has a generally L-shaped transverse cross-section so as to have a first limb part 25 secured to the inner surface of the inboard side wall 17 and a second, smaller limb part 26 secured to the inner surface of the support element

18. Figure 8 illustrates the arrangement shown in Figure 7 upon actuation of the inflator 14 so as to inflate the air-bag 15. As the air-bag 15 inflates, it bears against the second limb 26 of the frame 24 and deforms the frame 24 so as to urge the second limb 26 and the support element 18 forwardly, thereby breaking the frangible connection 23. The air-bag 15 inflates in a generally forwards direction and thus continues to deform the frame 24 until the second limb 26 becomes substantially aligned with the first limb 25, at which point the support element 18 becomes generally aligned with the side wall 17 in an operative position as illustrated in Figure 8. In this arrangement, the second limb 26 and the support element 18 both serve to provide lateral support to the inflated air-bag 15 in generally the same manner to that of the arrangement illustrated in Figure 5. The second limb 26 of the frame 24 can therefore also be considered to serve a supporting function in the same manner as the element 18.

The frame 24, due to its inherent resilience, can deform further from the position illustrated in Figure 8 in the event that it is subjected to a significant lateral force from the weight of an occupant of the seat in the event of a side impact situation. In such circumstances, the second limb 26 of the frame 24 and the support element 18 can yield or otherwise deform in an inboard direction to absorb energy from the movement of the seat occupant relative to the seat 1.

Figure 9 illustrates an air-bag unit in accordance with another embodiment of the present invention, in which the air-bag unit is mounted to the inboard side of the back-rest 3 of a motor vehicle seat so as to be initially covered by upholstery 30 of the seat 1. The back-rest 3 comprises a frame 31 having a pair of spaced-apart metal I-section beams 32 (only the inboard beam 32 being illustrated in Figure 9), each of which extends along a respective side region of the back-rest 3. The beam 32 comprises a generally planar side plate 33 carrying a pair of small end flanges 34, 35 at its front and rear edges respectively. It should be noted that whilst the illustrated arrangement comprises an I-section beam, other configurations of beam could be used instead, such as, for example, C-section or L-section beams.

The upholstery 30 of the back-rest 5 is wrapped around the frame 31 so as to define a bolster 36 on the inboard side of the back-rest 3. The bolster 36 extends forwardly of the central region of the back-rest so as to be located adjacent the inboard side of an occupant 4 sitting in the seat 1, thus providing a degree of lateral support. Of course, the bolster 36 illustrated in Figure 9 is the inboard bolster of the seat 1 and hence extends part-way between the seat occupant 4 and the centre of the motor vehicle within which the seat 1 is mounted.

In the region of the inboard bolster 36 illustrated in Figure 9, there is provided a cavity 37 in the upholstery 30 of the back-rest, within which the beam 32 is received. In the forwardmost region of the cavity 37, along the front of the bolster 36, there is provided a pre-defined break line 38 in the upholstery, along which the immediately adjacent regions of the upholstery 39, 40 are releasably secured to one another in a manner known per se, for example, using a breakable seam to hold the two regions of the upholstery 39, 40 together, and which is configured to break upon deployment of the air-bag.

The air-bag unit 5 is provided within the upholstery 39 of the back-rest 3, and is mounted to the beam 32 within the cavity 37. The air-bag unit 5 includes an inflator 41 such as, for example, a gas generator. The inflator 41 is secured to the inboard side of the side plate 33 of the beam 32 via a mounting bracket 42. The mounting bracket 42 is secured to the rearmost part of the beam 32, just forwards of the rear-end flange 35, by way of a conventional nut and bolt arrangement. From this point, the mounting bracket 42 extends forwardly along the inner surface of the plate 33, and then turns inwardly towards the centre of the back-rest 3 and slightly rearwardly so as to define an arcuate region which defines a concave recess within which the inflator 41 is received. The inflator 41 is mounted to the arcuate region of the mounting bracket 42 by way of another conventional nut and bolt arrangement 43.

The air-bag unit 5 also comprises an inflatable air-bag 44 made from fabric material which is fluidly connected to and extends generally forwardly from the inflator 41 into the main part of the recess 37. The air-bag 44 is mounted between the arcuate region of the mounting bracket 42 and a deflector shield 45 having a generally C-shaped cross-section. The bolt 43 mounting the inflator 41 to the mounting bracket 42 passes through the deflector shield 45 and the air-bag 44, to hold all of these components tightly together. The deflector shield 45 serves to protect the fabric of the air-bag 45 from the gas generated by the inflator 41 under high pressure, in the event that the air-bag unit 5 is actuated.

The air-bag 45 is initially provided in packed condition, in which it is packed via a number of zig-zag folds, within a protective cover or housing 46. The cover or housing 46 extends forwardly, from the general region of the inflator 41, to terminate at a position substantially adjacent the forwardmost end flange 34 of the beam 32. This forwardmost region of the housing 46 carries a forwardly and outwardly-directed reinforcing rib 47 which has a cut-out notch 48 configured to receive the innermost part of the forward end flange 34. The outboard region of the cover or housing 46 is provided with a tear-line 49 which is configured to break, for example by tearing or otherwise rupturing, in the event that the air-bag 45 is inflated upon actuation of the air-bag unit 5.

Turning now to consider Figure 10, actuation of the air-bag arrangement illustrated in Figure 9 will now be explained. Upon actuation of the air-bag unit 5, for example when an ignition signal indicative of an imminent or extant crash situation is received from a crash sensor, the inflator 41 is actuated, thereby serving to expel gas into the initially packed air-bag 45. This causes the air-bag to inflate and unfold, from the region of the inflator 41, in a forwards direction relative to the back-rest 3 of the seat. As it inflates, the air- bag 45 ruptures the cover or housing 46, along the predefined tear-line 49, so as to burst out of the cover or housing 46. Then, the inflating air-bag 45 also bursts through the break-line 38 of the bolster upholstery 30 so as to urge the regions 39, 40 of the upholstery immediately adjacent the break-line apart.

It will be seen from Figure 10 that the cover or housing 46 ruptures such that the forwardmost part of the cover or housing 46 pivots via the notch 48, about the innermost part of the forward end flange 34. However, the reinforcing rib 47 carried by the forwardmost region of the cover or housing serves to bear against the end flange 34 after a pre-determined degree of rotation, in order to limit the degree of this pivoting movement of the cover or housing 46, and hence to prevent the forwardmost part of the cover or housing 46 moving past the position illustrated in Figure 10, in which it will be seen that the forwardmost part of the ruptured cover or housing 46 extends generally forwardly from the beam 32 but is also directed slightly towards the occupant 4 of the seat. It will therefore be understood that the forwardmost part of the ruptured cover or housing 46 serves as a support element which moves during actuation of the air-bag unit 5 from its initial position illustrated in Figure 9 to its operative position illustrated in Figure 6 in which it extends forwardly and inboard of the inflated air-bag 45 so as to provide lateral support to the inflated air-bag in substantially the same manner as in the case of the support elements 18 of the embodiments illustrated in Figures 3 to 8.

Another embodiment of the present invention is illustrated in Figure 11, which again comprises an air-bag unit 5 mounted to the inboard side of the back-rest 3 of a vehicle seat 1.

In this arrangement, the air-bag unit 5 comprises a housing 50 which is preferably moulded from plastics material and which comprises a rear end wall 51, an outboard side wall 52 and an inboard side wall 53. The forward part of the housing 50 is initially closed by a door 54 which is secured to the forwardmost edge of the inboard side wall 53 via a frangible hinge 55. The outboard side edge of the door 54 is releasably connected to the forwardmost edge of the outboard side wall 52 by, for example, a frangible connection 56.

Mounted within the rear part of the housing 50 is an inflator 57 which preferably takes the form of a gas generator configured to generate gas upon receipt of a signal indicative of an imminent or extant crash situation.

The inflator 57 is located behind a deflector shield 58. In the region of the inflator 57, the deflector shield 58 is provided with a pair of gas-flow apertures 59 which allow the flow of gas therethrough from the inflator 57. A folded fabric air-bag 60 having an inlet aperture is mounted to the deflector shield 58 such that its inlet aperture fits over the gas flow apertures 59 provided through the deflector shield 58.

The deflector shield 58 has a forwardly-extending part 61 which takes the form of a substantially planar wall and is spaced from and substantially parallel with the inboard side wall 53.

Located within the space defined between the forwardly-extending wall part 61 of the gas deflector 58 and the inboard side wall 53 is a support element 62 in the form of a moveable plate. The moveable plate 62 is coupled to a piston-cylinder arrangement 63 which is spring-biased via a helically wound spring 64 towards the front of the housing 50. The piston-cylinder arrangement 63 is located generally adjacent the inflator 57 at a position behind the gas deflector 58, such that gas generated by the inflator 57 can flow towards and impinge on the piston-cylinder arrangement 63.

Figure 12 illustrates the air-bag unit 5 during inflation of the air-bag 6 by gas generated by the inflator 57. Gas generated by the inflator 57 passes through the gas flow apertures 59 formed in the deflector shield 58 and hence passes into the interior of the air-bag 60 thereby inflating the air-bag 60 in a generally forwards direction relative to the back-rest 3 of the seat. This causes the air-bag to bear against the inner face of the door 54, thereby rupturing the frangible connection 56 between the door 54 and the outboard side wall 52. The door 54 is therefore urged inboards, pivoting around the frangible hinge 55.

As the door 54 opens in this way, the moveable plate 62 was initially held by the closed door 54 in a position between the wall part 61 of the deflector shield 58 and the inboard side wall 53, against the biasing action of the spring 64, becomes free to move forwardly under the combined action of the spring 64 and the flow of gas from the inflator 57 towards the piston- cylinder arrangement 63.

The moveable plate 62 therefore moves from its initial position illustrated in 61 to the operative position illustrated in Figure 12 in which it extends generally forwardly on the inboard side of the inflating air-bag 60. The moveable plate 62 therefore provides a degree of lateral support to the inflating air-bag 60.

It will therefore be understood from the foregoing description that each of the alternative arrangements illustrated in Figures 3 through to 12 comprise a moveable support element which is moveable upon actuation of the air-bag unit from an initial position to an operative position, the operative position being located forwardly of the initial position and being such that when the respective support element is located in the operative position, the support element extends inboard of the inflated air-bag so as to provide a degree of lateral support to the inflated air-bag. It has been found that the respective support elements of the above-described embodiments provide the most effective lateral support to the respective inflated air-bags when the support elements have a dimension of between 70mm and 200mm in a forwards direction substantially perpendicular to the major axis of the back-rest of the seat (dimension (a) shown in figure 1), and a dimension of between 100mm and 250mm in a direction substantially parallel to the axis of the back-rest (dimension (b) shown in figure 1). It has also been found that the support elements of the various embodiments should most appropriately be spaced between 20mm and 100mm from the inboard side of the back-rest 3 of the seat 1. Support elements having the above-mentioned dimensions provide adequate lateral support to air-bags having a dimension extending forwardly and substantially perpendicular to the major axis of the back-rest of between 100mm and 300 mm (dimension (c) shown in figure 1).

Preferably, the airbags provided with such lateral support arrangements have a transverse thickness (d) shown in figure 5, for example) of between 100mm and 200mm when the airbag is inflated to an internal gas pressure of between 0.56bar and 3 bar.

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

Claims

CLAIMS:

1. An air-bag unit mounted to the inboard side of a vehicle seat, the air-bag unit comprising: an inflatable air-bag connected to an inflator actuable to inflate the air-bag, and a support element; the air-bag being configured to provide lateral protection to at least the thorax of an occupant of the seat, and the support element being moveable upon actuation of the air-bag unit from an initial position to an operative position, the support element being configured to extend inboard of the inflated air-bag when in said operative position so as to provide lateral support to at least part of the inflated air-bag.

2. An air-bag unit according to Claim 1, wherein said support element is resiliently deformable and configured, when in said operative position, to yield under a force exerted thereon by the weight of an occupant of the seat in a crash, thereby absorbing energy.

3. An air-bag unit according to Claim 1 or Claim 2, mounted to the backrest of the vehicle seat, wherein the inflator is positioned to direct gas into the air-bag in a generally forwards direction relative to the backrest, said support element being configured to move from said initial position to said operative position in a generally forwards direction relative to said backrest.

4. An air-bag unit according to any preceding Claim, further comprising a housing in which said air-bag and said inflator are provided, wherein said support element forms part of the housing.

5. An air-bag unit according to any preceding Claim, wherein said support element is mounted for pivotal movement from said initial position to said operative position.

6. A air-bag unit according to any preceding Claim, wherein said support element is configured to deform during movement from said initial position to said operative position.

7. An air-bag unit according to any preceding Claim, wherein said support element is moved from said initial position towards said operative position by engagement with the air-bag during inflation of the air-bag.

8. An air-bag unit according to any one of Claims 1 to 4, wherein said support element is slidably mounted for slideable movement from said initial position to said operative position.

9. An air-bag unit according to Claim 8, wherein said support element is resiliently biased towards said operative position.

10. An air-bag unit according to Claim 9, wherein said resilient bias is provided by a spring.

11. An air-bag unit according to any one of Claims 8 to 10, configured to direct a flow of gas from the inflator towards the support element such that said support element is urged from said initial position towards said operative position by said flow of gas.

12. An air-bag unit according to any preceding Claim mounted to the vehicle seat so as to be at least partially covered by upholstery.

13. An air-bag unit according to any preceding Claim, wherein the air-bag is configured also to provide lateral protection to the head of an occupant of the seat.

14. An air-bag according to any preceding Claim, wherein said support element has a dimension (a), in a direction substantially perpendicular to the axis of the back-rest of the seat, of between 70mm and 200mm.

15. An air-bag according to any preceding Claim, wherein said support element has a dimension (b), in a direction substantially parallel to the axis of the back-rest of the seat, of between 100mm and 250mm.