An air-bag arrangement in the form of inflatable curtain (1) has a plurality of inflatable regions (12, 19, 25) spaced from the front of the inflatable curtain to the rear of the inflatable curtain. The rear-most inflatable region (25) is connected by a gas flow passage (23) to the lower-most part of an inflatable chamber (22) forming part of the next forward inflatable region (19) at a point remote from the point where a gas flow duct (8) associated with a gas generator (7) injects gas into that chamber (22). The rear-most inflatable region (25) of the inflatable element does not inflate until after the two forward regions (12, 19) have inflated, and possibly does not open until the region (19) connected to the gas flow passage(23) has been struck by the head of an occupant. An occupant in a rear-most row of seats is normally spaced further from the inflatable curtain than a more forwardly positioned occupant, and thus the rear-most chamber (25) will be inflated before being struck by a rear occupant.

BACKGROUND OF THE INVENTION

1. Field of the Invention

THE PRESENT INVENTION relates to an air-bag arrangement, and more particularly relates to an air-bag arrangement in the form of an inflatable curtain.

2. Description of Related Art

It has been proposed to provide an inflatable curtain in a motor vehicle. The inflatable curtain is in the form of an air-bag which is initially mounted and stored, for example, in the roof lining of the vehicle at a position above the door openings at the side of the vehicle. In response to an accident, especially a side impact or roll-over accident, the inflatable curtain inflates and extends downwardly from its mounting position, to extend adjacent the windows in the motor vehicle. The inflatable curtain is positioned between the head of each occupant and the adjacent window, thus providing a degree of protection for the head of the occupant and minimising the risk that the head of the occupant will be thrown out, through the window opening, after the window has broken during the accident.

Inflatable curtains are often formed from air-bags having inflatable regions and uninflatable regions, with the inflatable regions being divided into one or more elongate cells or chambers. Each inflatable region is located at a position where it is most likely that the head of an occupant will strike the inflatable curtain during an accident. It is desirable for each inflatable region to be inflated before the head of an occupant adjacent that inflatable region strikes the inflatable curtain.

It has been found that in many motor vehicles, especially vehicles having multiple rows of seats, an occupant in the rear-most row of seats is positioned, probably due to the presence of a rear wheel mudguard, closer to the centre or axis of the vehicle than a vehicle occupant sitting further towards the front of the vehicle. Thus the head of an occupant towards the front of the vehicle will almost inevitably impact with an inflatable curtain before the head of an occupant of the rear-most row of seats. This applies especially in connection with a vehicle having three rows of seats, but may also apply to some vehicles having two rows of seats.

It is desirable to inflate an inflatable curtain using a minimum quantity of gas to minimize the costs and the weight of the gas generator. Also, it is further desirable for an inflatable curtain to be inflated within a very short period of time, for example, during a time period of approximately 18 mS.

SUMMARY OF THE INVENTION

The present invention seeks to provide an improved air-bag arrangement in the form of an improved inflatable curtain.

In this Specification forward and front are intended to refer to that part of the air-bag which is to be located towards the front of the vehicle, and rear is intended to refer to that part of the air-bag which is to be located towards the back of the vehicle.

According to this invention there is provided an air-bag arrangement in the form of an inflatable curtain, the inflatable curtain comprising an inflatable element, the inflatable element, at one edge, being provided with a gas supply duct associated with a gas generator, mounting elements being provided to mount the inflatable element to the motor vehicle, a front-most mounting element being present on an extension means extending from a forward-most part of the inflatable element to be connected to a mounting on an “A”-Post of the vehicle, and further mounting means serving to mount at least the gas generator and the associated gas supply duct to the roof line of the motor vehicle, the inflatable element being divided into separate inflatable zones to provide protection for vehicle occupants seated one-behind-the-other, the gas supply duct being connected to inject gas directly into at least one forward-most inflatable zone, the rear-most inflatable zone being connected to the next forward inflatable zone by means of a gas flow passage, the gas flow passage communicating with said next forward inflatable zone at a position remote from the gas supply duct.

Preferably at least one inflatable region is divided into a plurality of chambers or cells so that, on inflation of the inflatable element, the length of the inflatable element between a rear-most mounting element and the front-most mounting element is reduced.

Conveniently the inflatable element includes at least one uninflatable region located between and separating two adjacent, but spaced apart inflatable regions.

In a preferred embodiment the said gas supply passage is initially closed by a tear seam adapted to tear to open the gas flow passage when subjected to a predetermined pressure.

In one embodiment of the invention the rear-most inflatable zone is adapted to inflate after the next forward inflatable zone has reached a predetermined gas pressure.

In another embodiment of the invention the rear-most inflatable zone is adapted to inflate after the head of the occupant in front of the rear-most occupant has struck the said next forward inflatable zone.

In one embodiment the arrangement is for use in a vehicle with three rows of seats, the inflatable element comprising a forward-most inflatable region, and an intermediate inflatable region which communicates with said gas flow duct leading to a third, rear-most inflatable region.

In an alternative embodiment the inflatable element is for use in a motor vehicle having two rows of seat, the inflatable element comprising a forward-most inflatable region which communicates with said gas flow duct leading to a rear-most inflatable region.

Conveniently the extension is a strap.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially toFIG. 1, an inflatable curtain1is shown mounted in position within a motor vehicle. The motor vehicle is intended to contain three rows of passengers. Illustrated inFIG. 1is the “A”-Post2which is located towards the front of the vehicle, a “B”-Post3, a “C”-Post4and a “D”-Post5. A roof rail6extends across the top of the door or window openings formed between the various posts.

The inflatable curtain1is provided with a gas generator7which is connected to an elongate gas supply duct8which is secured to the roof rail6, and which extends into the upper part of an inflatable element9which constitutes the inflatable curtain. The inflatable element has its upper edge secured to the gas duct8. The gas duct8is provided with various apertures10at selected positions spaced apart along its length through which gas may emerge from the gas duct into inflatable regions of the inflatable element9.

The inflatable element9is of generally rectangular form, and, at the end of the inflatable element9located at the forward-most position in the motor vehicle, an extension in the form of a strap10is provided which extends from a point in the region of the lower edge of the inflatable element to a mounting11provided at a point on the “A”-Post2below the line of the roof rail6. The strap10is provided with an appropriate connecting element to connect the strap to the mounting11.

The forward-most part12of the inflatable clement is an inflatable region provided with substantially vertical extending seams13,14, which divide the region12into three inflatable cells or chambers15,16,17. The chambers are of elongate form, and each chamber defines an axis which, in the described embodiment, is substantially vertical, thus extending perpendicularly to the lower-most edge of the inflatable element9. Each chamber15,16,17is aligned with a respective opening10formed in the gas supply duct8so that the chambers may receive gas from the gas generator7.

The rear-most edge of the rear-most chamber17is bounded by an uninflatable region18of the inflatable element. To the rear of the uninflatable region18there is provided a further inflatable region19which is divided by a single seam20into two cells or chambers21,22. Bach of these cells21,22is associated with a respective opening10in the gas supply duct8. The uninflatable region18is thus located between, but separates, the two inflatable regions12and19. At the rear-most part of the rear-most chamber22of the inflatable region19, at a position adjacent the lower-most edge of the inflatable element9, a gas flow passage23is defined which extends beneath a non-inflatable region24of the inflatable element, to a single inflatable chamber25formed at the very rear of the inflatable element.

At the rear of the inflatable element, just above the inflatable chamber25, is an anchoring lug26by means of which this part of the inflatable element may be secured to the roof rail6.

The inflatable element is mounted in position by mounting the gas generator7and the associated gas supply duct firmly in position to the roof rail6, by connecting the connecting element provided at the forward-most end of the strap10to the mounting11, and by connecting the mounting lug26to the roof rail6. It may have more mounting lugs between the mounting lug26and the strap10.

The inflatable element will normally be in a folded condition stored within a recess or housing which extends immediately adjacent the gas generator7and the gas supply duct8. The strap10will be accommodated within an extension of the recess which extends along the “A”-Post2, or will at least be concealed behind trim provided on the “A”-Post.

In the event that a side impact or roll-over accident should occur, the gas generator will generate gas which will flow along the gas supply duct8and inflate the inflatable element in a manner which will be described in greater detail below.

FIG. 2is a figure provided for explanatory purposes and illustrates the situation that would exist if the inflatable element9were to be fully inflated whilst three occupants of the vehicle, seated one behind the other, were in their ordinary positions.

It can be seen that as the air-bag has become inflated, the various cells or chambers15,16,17,21,22and25have all become inflated and have adopted a substantially cylindrical or oval form. Here it is to be understood that if the inflatable element9were laid out flat, before inflation, the distance between the anchoring lug26and the forward-most end of the strap10provided with the connecting element which engages the mounting11could be measured. On inflation, because the cells or chambers aft-the oval or rounded form, as shown inFIG. 2, this distance would be reduced. Here it is to be understood that the inflatable element9is so designed that, in the uninflated state the inflatable element may be stated within the recess provided for that purpose, because the actual length of the recess between the mounting lug26and the forward-most end of the strap10on the inflatable element is greater than the distance in a straight line between the point in the roof line6adapted to receive the mounting lug26and the mounting11on the “A”-Post of the motor vehicle. On inflation of the inflatable element, however, because the cells or chambers adopt the rounded or oval configuration, the inflatable element becomes tensioned, and a line o^ tension is created which extends from the forward-most mounting11on the “A”-Post2to the point where the lug26is secured to the roof of the vehicle. The inflatable element is thus held firmly in the desired position, and any tendency for the lower-most part of the inflatable element to flap about is minimized.

As can be seen inFIG. 2, the vehicle has three occupants seated adjacent the inflatable element9. The first occupant30is the driver or a front seat passenger, and the head of the driver or front seat passenger is separated by a distance D1, from the adjacent chambers15,16,17, which are positioned to provide protection especially as regards impact with the “B”-Post3of the motor vehicle. Similarly for the next occupant of the vehicle,31, who is seated directly behind the first occupant30, the head of the occupant is spaced from the adjacent inflated chambers21,22by a distance D2. Finally, the third occupant of the vehicle,32, is shown in position behind the first two occupants, and the head of the third occupant is spaced from the adjacent chamber25by a distance D3. Because the rear-most occupant32is sitting closer to the axis of the vehicle than the occupants in front of him, the distance between the head of the third occupant32and the adjacent inflated cell or chamber25, distance D3, is greater than distance D1and is greater than distance D2.

Consequently it is to be understood that in a side impact situation, the head of the first occupant30and the head of the second occupant31will almost certainly strike the inflatable element before the head of the third occupant32strikes the inflatable element. As has been mentioned, it is important that the inflatable element should be inflated before the head of the occupant strikes that part of the inflatable element that is to protect the occupant.

Returning toFIG. 1, it can be seen that gas from the gas supply duct8is fed directly to the first inflatable region12, and to the second inflatable region19and thus, on actuation of the gas generator7, the inflatable region12and the inflatable region19become inflated very rapidly. However, the rear-most inflatable chamber25is only inflated by gas flowing through the gas flow passage23which communicates with part of the chamber22which is remote from the gas supply duct8. Thus the chamber22must become substantially inflated or the pressure within the chamber22must be raised in some other way, before gas will flow through the gas flow passage23to inflate rear-most chamber25.

Turning now toFIG. 3, which corresponds generally withFIG. 2, but illustrates a situation that can exist when the inflatable element9is being inflated, it is to be seen that at a stage during a side impact situation, shortly following sensing of the side impact situation, the inflatable region12is fully inflated and the inflatable region19is fully inflated, but the rear-most chamber25is not fully inflated. If the heads of the occupants of the vehicle all move effectively towards the side of the vehicle, the heads of the occupants30,31will strike the inflatable curtain before the head of the rear-most occupant32. As the head of the occupant31impacts with the inflated region19, the pressure of gas within the chamber22will rise substantially causing a flow of gas along the gas flow duct23to fully inflate the rear-most chamber25. The rear-most chamber25is thus fully inflated before the head of the rear-most occupant32impacts with that chamber25, as shown inFIG. 4.

It is to be appreciated that the tension that is created in the inflatable element between the mounting lug26and the fixing provided at the forward end of the strap10is provided almost completely by the tensioning effect provided by the chambers15,16,17,21and22. The rear-most chamber25does not effectively contribute to the creation of the line of tension. Thus an adequate line of tension is present before the rear-most chamber25becomes inflated.

Turning now toFIG. 5of the accompanying drawings which illustrates a modified embodiment of the invention, it can be seen that in this embodiment of the invention the gas flow passage23has the end thereof communicating with the chamber22initially sealed by means of a tear seam27. The tear seam is adapted to tear when pressure within the chamber22exceeds a predetermined threshold. The threshold may be reached on ordinary inflation of the air-bag without the chamber22being impacted by the head of an adjacent occupant, or the pressure necessary to burst the tear seam may only be experienced when the chamber22is at least partially inflated and is impacted by the head of an occupant of the vehicle.

FIG. 6illustrates a modified embodiment of the invention intended for use in a motor vehicle where there are only two rows of seats. In this embodiment, parts of the described embodiment which are identical with parts of the previously described embodiment, are given the same reference numerals and will not be re-described.

It is to be observed that in the embodiment ofFIG. 6, an inflatable element40is provided which is associated with a gas generator7, and gas supply duct8of the type described above. The inflatable element40has a front-most inflatable region41divided into four chambers or cells42,43,44and45, this region being adapted to provide protection for the head of the driver. The rear-most part of the rear-most cell45of the inflatable region45is associated with a gas flow duct46which communicates with the cell45at a position remote from the gas supply duct8. The gas flow passage46may initially be sealed by a tear seam. The gas flow passage46extends beneath an uninflatable region47of the inflatable element40to communicate with two cells48,49provided at the rear-most part of the inflatable element40to provide protection for a rear seat passenger.

It is to be understood, of course, that a very high proportion of all journeys carried out in motor cars which can carry passengers in two rows of seats, are completed with no passengers present in the rear row of seats. Thus, in the majority of side impact or roll-over accidents, the primary function of the inflatable curtain is to provide protection for a person sitting in the front row of seats.

In the embodiment now described, the part of the inflatable element41which is to provide protection for a driver or front seat occupant is inflated initially, with the direct injection of gas from the gas flow duct8, and finally the inflatable region constituted by the cells48and49, which is to provide protection for a rear seat passenger, is inflated. The inflation of the rearward-most part may be effected with the passage of time, or, as in the embodiment described above, inflation of the rearward-most part may be at least assisted by an impact of the head of a front seat occupant on that part of the inflatable element which is intended to provide protection for a front seat occupant.

The present invention provides an inflatable curtain which will provide protection for occupants of a motor vehicle seated in multiple rows of seats, but provides an inflatable curtain which can be inflated to an operative condition providing protection for occupants of the vehicle in front of the rear-most occupant within a very short period of time, with the area of the inflatable curtain that is to provide protection for the rear-most occupant becoming inflated subsequently, with that inflation possibly being assisted or initiated by the impact of the head of an occupant in front of the rear-most occupant with part of the inflatable element.

In the present Specification “comprise” means “includes or consists of” and “comprising” means “including or consisting of”.