GB2477570A

GB2477570A - A ventilation arrangement

Info

Publication number: GB2477570A
Application number: GB1002092A
Authority: GB
Inventors: Peter Axelsson
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2010-02-09
Filing date: 2010-02-09
Publication date: 2011-08-10
Also published as: GB201002092D0

Abstract

A ventilation arrangement for an air-bag comprising: a valve 1 adapted to be mounted to an air-bag, the valve 1 having a first chamber 4 that is in fluid communication with the 3 inlet, a venting aperture 7 and a communication aperture 8; and a cover 9 that is attached to the valve, has a pressure chamber 13 which is in communication with the first chamber 4 through the communication aperture 8 and has a pressure element which is adapted to move under the influence of gas pressure when the gas pressure within the pressure chamber 13 exceeds a predetermined threshold, so that the cover 9 moves from a closed position or configuration, in which the cover 9 substantially blocks the venting aperture 7, thereby preventing gas from escaping from the first chamber 4 through the venting aperture 7, to an open position or configuration, in which the cover 9 does not block the venting aperture 7 and allows gas to escape from the first chamber 4 through the venting aperture 7.

Description

Title: A Ventilation Arrangement

Description of Invention

THIS INVENTION relates to a ventilation arrangement, and in particular concerns an arrangement to allow ventilation of an air-bag following inflation.

It is well-known to provide inflatable air-bags to protect vehicle occupants in the event of a crash or other accident when activated, air-bags of this type need to be inflated rapidly to relatively high pressures. However, the air-bags only need to remain inflated at high pressure for a relatively short period of time in order to provide a protective function. Once this time has elapsed, the presence of the inflated air-bag inside the vehicle is unwanted, as it will hinder movement and/or escape of vehicle occupants. It is therefore desirable for venting in an air-bag to be opened once a certain length of time has elapsed following deployment of the air-bag.

Many designs of air-bag include vents to allow air to escape from the interior of the air-bag, particularly as a vehicle occupant is thrown against the air-bag.

However, vents of appropriate size to allow the air-bag to deflate during a crash situation are, in general, not sufficiently large to allow adequate venting of the air-bag after the crash event.

It is therefore an object of the invention to provide a venting arrangement for an air-bag which, after a certain length of time has elapsed following deployment of the air-bag, allows effective venting of gas from the air-bag interior.

Accordingly, one aspect of the present invention provides a ventilation arrangement for an air-bag, comprising: a valve adapted to be mounted to an air-bag, the valve having a first chamber that is in fluid communication with the inlet, a venting aperture and a communication aperture; and a cover that is attached to the valve element, has a pressure chamber which is in communication with the first chamber through the communication aperture and has a pressure element which is adapted to move under the influence of gas pressure when the gas pressure within the pressure chamber exceeds a predetermined first threshold, so that the cover moves from a closed position or configuration, in which the cover substantially blocks the venting aperture, thereby preventing gas from escaping from the first chamber through the venting aperture, to an open position or configuration, in which the cover does not block the venting aperture and allows gas to escape from the first chamber through the venting aperture.

Advantageously, the cover is, in the closed position or configuration, fitted over an end of the valve and, when moving from closed position or configuration to the open position or configuration, moves in a direction so as to be removed from the valve.

Preferably, the cover slides when moving from the open position or configuration to the closed position or configuration.

Conveniently, the cover rotates when moving from the open position or configuration to the closed position or configuration.

Advantageously, at least one venting aperture is formed on side surface of the valve, and the communication aperture is formed in an end surface of the valve, and wherein the cover element fits over the valve, in the closed position or configuration, so that a blocking portion of the cover substantially covers the at least one venting aperture.

Preferably, the venting arrangement further comprises a deformable closure element which is positioned within the first chamber and, in a default position, is spaced apart from the communication aperture, allowing gas to flow from the first chamber, through the communication aperture and into the pressure chamber, and when the gas pressure within the first chamber exceeds a threshold, the closure element deforms to lie against the communication aperture, thereby blocking the communication aperture and preventing gas from flowing from the first chamber through the communication aperture into the pressure chamber.

Conveniently the ventilation arrangement further comprises a biasing arrangement which, when the cover is in the closed position or configuration, exerts a biasing force to drive the cover into the open position or configuration.

Advantageously, the forces exerted by the biasing arrangement are not, by themselves, sufficient to move the cover from the closed position or configuration to the open position or configuration.

Preferably, the ventilation arrangement further comprises a retaining arrangement which attaches the cover releasably to the valve element in the closed position or configuration, thus increasing the threshold of gas pressure within the pressure chamber that is required to move the cover from the closed position or configuration to the open position or configuration.

Conveniently, the retaining arrangement comprises a holding element, attached to one of the valve and the cover, and an engagement element, held by the other of the valve and the cover, a predetermined force being required to separate the engagement element from the holding element.

Another aspect of the present invention provides an air-bag arrangement comprising an air-bag and a ventilation arrangement according to the above, the interior of the air-bag being in fluid communication with the inlet.

A further aspect of the present invention provides a vehicle comprising an air-bag arrangement according to the above.

In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: figure 1 shows a valve suitable for use with the present invention; figures 2 and 3 show components of a venting arrangement embodying the present invention; figures 4 to 7 show the venting arrangement of figures 2 and 3 in open and closed positions; and figures 8 to 10 show parts of alternative venting arrangements embodying the present invention.

Referring firstly to figure 1, a valve 1 is shown. The valve 1 includes a mounting portion 2, which allows the valve 1 to be connected to an air-bag.

In the depicted embodiment the mounting portion 2 comprises a generally cylindrical collar, around which the neck of an aperture in an air-bag (not shown) can be clamped or otherwise attached.

The mounting portion 2 has a flow path 3 defined therethrough (i.e. the passage through the hollow interior of the mounting portion 2), and the flow path 3 leads into a first chamber 4. In the depicted embodiment the first chamber 4 is defined by one or more side walls 5 (preferably, a generally cylindrical side wall 5) and an end wall 6.

One or more venting apertures are formed to allow gas within the first chamber 4 to escape therefrom. In the embodiment shown four venting apertures 7 are formed in the side wall 5 of the first chamber 4.

A communication hole 8 is formed in the end wall 6 of the first chamber 4.

One or more communication holes may, in other embodiments, be formed in alternative location(s).

Turning to figure 2, a cover 9 is also provided. The cover 9 has a blocking portion 10 which has an internal cross-section which preferably generally matches the external cross-section of the first chamber 4 (in the depicted embodiment, therefore, the blocking portion 10 of the cover 9 is generally cylindrical). The blocking portion 10 has an open end 11, which allows the blocking portion 10 to be placed over the valve 1. At its other end, the cover 9 is narrowed and defines a shoulder region 12 which fits over a periphery of the end wall 6 of the valve 1. Beyond the shoulder region 12 an enclosed second chamber 13 is defined, having an end wall 23.

In embodiments of the invention a retaining element 32 is provided as part of the valve 1. The retaining element 32 comprises a clip which is attached to the mounting portion 2, and has a pair of protrusions 14 which project from the clip and define a retaining aperture 15 having a narrowed neck.

An engagement element 16 is also provided, and is adapted to be attached to the cover 9 and releasably held by the retaining element 32. In the depicted embodiment the engagement element 16 comprises an elongate bar 17 having holding portions 18 provided at either end thereof, the holding portions 18 being bent through around 900 with respect to the bar 17. The bar 17 is of suitable diameter that it may be received in the aperture of the retaining element 32, but is wider than the neck of the aperture 15, and so may not be removed from the aperture 15 unless a significant withdrawal force acts on the bar 17.

The cover 9 is provided with a pair of attachment holes 19 which are formed through opposing regions of the blocking portion 10. These attachment holes 19 are suitably sized so that the engagement element 16 may be installed in the cover 9, with the bar 17 extending between the attachment holes 19, and the holding portions 18 outside the cover 9.

To assemble the components shown in figure 2, the retaining element 32 is installed in the mounting portion 2 of the valve 1. The cover 9 is then placed over the end of the valve 1, so that the blocking portion 10 thereof blocks the venting apertures 7 of the first chamber 4. The engagement element 16 is then passed through the attachment holes 19 formed in the cover 9, and is pressed into place so that the bar 17 of the engagement element 16 is held in the aperture 15 of the retaining element 32. The assembled components form a venting arrangement 20, as shown in figure 3.

Use of the venting arrangement 20 will now be described, with reference to figures 4 and 5.

The venting arrangement 20 is attached to an air-bag so that the first chamber 4 is in fluid communication with the interior of the air-bag, through the mounting portion 2. While the air-bag is in its folded, pre-deployment state, the venting arrangement 20 may be contained within the folds of the air-bag, or in any other suitable location.

When the air-bag is deployed, the air-bag will be inflated rapidly and reach a state where the interior of the air-bag is filled with high-pressure gas. High-pressure gas will therefore flow through the mounting portion 2 and into the first chamber 4, as shown by arrows 21 in figure 4. The gas pressure within the first chamber 4 will rise above that in the second chamber 13, and gas will therefore flow from the first chamber 4, through the communication aperture 8, into the second chamber 13, as indicated by arrows 22 in figure 4. The communication aperture 8 is formed to have a relatively small cross-section, however, and so the rate of flow of gas from the first chamber 4 into the second chamber 13 is relatively low. This rate can, of course, be influenced by controlling the cross-sectional diameter of the communication hole 8.

As the pressure in the second chamber 13 grows, the gas within the second chamber 13 will exert outward forces on the inner surfaces of the second chamber 13. A force will therefore act on the inner surface of the end wall 23 of the cover 9, which will tend to lift the cover 9 away from the valve 1. This force will, initially, be resisted by frictional forces between the cover 9 and the valve 1. Additionally, the engagement element 16, which is held by the retaining element 32, will also prevent the cover 9 from moving with respect to the valve 1. However, when the force acting on the end wall 23 of the cover 9 exceeds a first threshold, the frictional forces between the cover 9 and the valve 1 will be overcome, and the engagement element 16 will be withdrawn from the retaining element 32.

When this occurs, the cover 9 will slide off the valve 1, 50 that the blocking portion 10 of the cover 9 no longer covers the venting apertures 7 of the first chamber 4. This has the effect of opening relatively large passages from the interior of the air-bag to the surrounding atmosphere, and gas can therefore be vented from the air-bag interior at a very high rate, as shown in figure 5.

The force acting on the end wall 23 of the cover 9 is shown in figure 5 by an arrow 24.

The venting arrangement 20 is shown in figures 6 and 7 before and after the cover 9 has moved to open the vent aperture 7, respectively. In these figures the neck 25 of an air-bag can be shown, attached to the mounting portion 2 by means of a securing band 26.

In this embodiment the end wall 23 of the cover 9 acts as a pressure element, against which gas within the second chamber 32 presses, and which moves when the pressure within the second chamber 32 exceeds the first threshold.

In other embodiments, however, the pressure element need not be a wall or part of the chamber, and may be a separate element which is contained within the second chamber, or forms part of, or is positioned within, a further arrangement which is in fluid connection with the interior of the second chamber 32.

Referring to figures 8 and 9, in embodiments of the invention a resilient, deformable closure element 27 is provided. The closure element 27 lies against the inner surface of the end wall 6 of the valve 1 and has a plurality of apertures 28 formed therein (in other embodiments only one aperture may be provided). In its default state the closure element 27 is convex, and is arranged so that a central region of the closure element 27 is spaced apart from the inner surface of the end wall 6. The closure element 27 therefore lies over, but does not block, the communication aperture 8 However, if a sufficient force is applied to the central region of the closure element 27, in the direction of the end wall 6, the closure element 27 can be deformed to lie flat against the end wall 6, as shown in figure 9. None of the apertures 28 formed in the closure element 27 are aligned with the communication aperture 8 50 that, when the closure element 27 is deformed as described above, the closure element 27 blocks off the communication aperture 8 and hence effectively prevents gas from flowing from the first chamber 4 to the second chamber 13.

During normal inflation of the air-bag, forces 30 arising from the pressure of gas in the first chamber 4 which act on the closure element 27 are not sufficient to deform the closure element 27, and so gas can still travel along a flow path 29 from the first chamber 4, through the apertures 28 of the closure element 27 and the communication aperture 8, and into the second chamber 13.

However, if the gas pressure within the first chamber 4 exceeds a second threshold, which is likely to be indicative of the action of a passenger or pedestrian being thrown against an air-bag, the forces 30 acting on the closure element 27 that arise from the pressure of gas within the first chamber 4 will be sufficient to deform the closure element 27 and block the flow of gas from the first chamber 4 to the second chamber 13, to ensure that, in a crash situation, the air-bag is not vented too early.

Turning to figure 10, a further embodiment is shown in which a biasing arrangement is provided to assist in the opening of the venting arrangement 20. In the depicted embodiment the biasing arrangement takes the form of a compression spring 31 which is placed between the outer surface of the end wall 6 of the valve 1, and the inner surface of the end wall 23 of the cover 9.

The spring 31 is, prior to deployment of the air-bag, under compression, and hence exerts forces on the cover 9 and valve 1 that tend to drive the cover 9 away from the valve 1, thus opening the venting apertures 7 of the main chamber 4. However, prior to deployment of the air-bag these forces are not sufficiently large to separate the cover 9 from the valve 1.

During deployment the pressure of gas in the second chamber 13 rises in the normal way. As soon as the forces which tend to lift the cover 9 away from the valve 1 have reached a sufficiently high level (both through the gas pressure in the second chamber 13 and the forces produced by the spring 31) the cover 9 will move away from the valve 1, opening the venting apertures 7 of the gas chamber 4. The spring 31 will ensure that, as soon as this starts to occur, the cover 9 moves sufficiently to open the venting apertures 7 fully.

The provision of a biasing arrangement of this type helps to ensure that the venting arrangement 20 opens correctly, even if the pressure in the air-bag is relatively low.

It will be understood that any other suitable type of biasing arrangement may be provided, and the invention is not limited to the use of springs.

It will be understood that it is not necessary for the entire cover to move in order to open the venting apertures 7. In some embodiments, a part of the cover may move, while the rest of the cover remains substantially stationary.

For instance, the blocking portion of the cover may have inner and outer layers, which each have apertures formed therethrough. In an initial configuration, the apertures in the two layers are not aligned, and so gas may not pass through the blocking portion. The inner layer is attached to a pressure surface at one end of the second chamber, and both of these components are rotationally attached to the main part of the cover, through a threaded attachment. When the pressure in the second chamber rises beyond a predetermined threshold, the pressure surface is driven to rotate (as a result of the threaded attachment) with respect to the main part of the cover, and as it does so the inner layer rotates with respect to the outer layer, so that the apertures through the inner and outer layers align with one another, allowing gas to be vented to the surrounding atmosphere.

Indeed, the entire cover could be rotationally attached to the valve in a similar manner, so that the cover rotates with respect to the valve to open the venting apertures.

In embodiments of the invention an air-bag may be provided with several venting arrangements 20, placed at suitable locations around the air-bag.

It is expected that additional venting provided by the biasing arrangement embodying the invention may allow swift retraction of an air-bag following inflation, by means of an active retraction system. Such a system may comprise, for example, one or more lines or tethers which are attached to the air-bag which, after a length of time has elapsed following deployment, are retracted, for instance by the winding or one or more spools, to withdraw the air-bag actively.

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.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS: 1. A ventilation arrangement for an air-bag, comprising: a valve adapted to be mounted to an air-bag, the valve having a first chamber that is in fluid communication with the inlet, a venting aperture and a communication aperture; and a cover that is attached to the valve element, has a pressure chamber which is in communication with the first chamber through the communication aperture and has a pressure element which is adapted to move under the influence of gas pressure when the gas pressure within the pressure chamber exceeds a predetermined first threshold, so that the cover moves from a closed position or configuration, in which the cover substantially blocks the venting aperture, thereby preventing gas from escaping from the first chamber through the venting aperture, to an open position or configuration, in which the cover does not block the venting aperture and allows gas to escape from the first chamber through the venting aperture.
2. A ventilation arrangement according to claim 1 wherein the cover is, in the closed position or configuration, fitted over an end of the valve and, when moving from closed position or configuration to the open position or configuration, moves in a direction so as to be removed from the valve.
3. A ventilation arrangement according to claim 1 or 2, wherein the cover slides when moving from the open position or configuration to the closed position or configuration.
4. A ventilation arrangement according to any preceding claim, wherein the cover rotates when moving from the open position or configuration to the closed position or configuration.
5. A ventilation arrangement according to any preceding claim wherein at least one venting aperture is formed on side surface of the valve, and the communication aperture is formed in an end surface of the valve, and wherein the cover element fits over the valve, in the closed position or configuration, so that a blocking portion of the cover substantially covers the at least one venting aperture.
6. A venting arrangement according to any preceding claim further comprising a deformable closure element which is positioned within the first chamber and, in a default position, is spaced apart from the communication aperture, allowing gas to flow from the first chamber, through the communication aperture and into the pressure chamber, and when the gas pressure within the first chamber exceeds a threshold, the closure element deforms to lie against the communication aperture, thereby blocking the communication aperture and preventing gas from flowing from the first chamber through the communication aperture into the pressure chamber.
7. A ventilation arrangement according to any preceding claim further comprising a biasing arrangement which, when the cover is in the closed position or configuration, exerts a biasing force to drive the cover into the open position or configuration.
8. A ventilation arrangement according to claim 7 wherein the forces exerted by the biasing arrangement are not, by themselves, sufficient to move the cover from the closed position or configuration to the open position or configuration.
9. A ventilation arrangement according to any preceding claim further comprising a retaining arrangement which attaches the cover releasably to the valve element in the closed position or configuration, thus increasing the threshold of gas pressure within the pressure chamber that is required to move the cover from the closed position or configuration to the open position or configuration.
10. A ventilation arrangement according to claim 9 wherein the retaining arrangement comprises a holding element, attached to one of the valve and the cover, and an engagement element, held by the other of the valve and the cover, a predetermined force being required to separate the engagement element from the holding element.
11. An air-bag arrangement comprising an air-bag and a ventilation arrangement according to any preceding claim, the interior of the air-bag being in fluid communication with the inlet.
12. A vehicle comprising an air-bag arrangement according to claim 11.
13. A ventilation arrangement substantially as hereinbefore described, with reference to the accompanying drawings.
14. An air-bag arrangement substantially as hereinbefore described, with reference to the accompanying drawings.
15. A vehicle substantially as herein before described, with reference to the accompanying drawings.
16. Any novel feature or combination of features disclosed herein.