GB2341583A

GB2341583A - An air bag arrangement

Info

Publication number: GB2341583A
Application number: GB9920141A
Authority: GB
Inventors: Homayoun Karimi
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1998-09-19
Filing date: 1999-08-26
Publication date: 2000-03-22
Also published as: GB9920141D0; GB9820340D0

Abstract

A guide tunnel 6 defined by the vehicle's steering wheel 1 confines the expansion of the air bag 9 so that, in the event of a crash, initially a lower part 10 of the air bag is directed by the tunnel to engage with an occupant's legs and lower torso before pressure vents 12 open and an upper part 11 of the bag inflates to protect the occupant's upper torso and head. The steering wheel is of a split cone configuration (see Figure 1) so that the lower abdomen of the vehicle occupant is not exposed to contact with a robust surface as would be the case with a conventional circular wheel and, in this respect, the wheel has orientation means to return the wheel to its normal position should it have been turned so that the grip 4 is adjacent the occupant's lower torso. The steering wheel is hinged about its dashboard mounting end 5 so that as the air bag inflates the wheel can either be lifted into a less dangerous position or rotated in the opposite sense to arrow A so that the guide tunnel further confines the bag's expansion. The steering wheel may be biased about the hinge under it own weight or be provided with a spring loaded mechanism. In an alternative embodiment the wheel is presented in an upturned configuration so that the initial deployment of the air bag is confined between the guide tunnel and the windscreen of the vehicle.

Description

I,- AN AIR BAG ARRANGEMENT The present invention relates to an air bag

arrangement and more particularly to such an arrangement associated with a steering wheel of a motor vehicle.

Traditionally, steering wheels have comprised a round wheel to enable an occupant to operate the steering mechanism of a motor vehicle by simple rotation.

Unfortunately, in a vehicle collision the lower half of such a round steering wheel can precipitate severe abdominal injuries to an occupant. Thus. an air bag mechanism is generally included within the steering wheel in order to protect the occupant from such injuries, etc. This air bag mechanism is typically deployed as a simple balloon-type air bag from the centre hub of the steering wheel towards the occupant. In such circumstances, the occupant has not been fully protected and consequently injuries may still result.

More recently, attempts have been made to provide split or truncated steering wheels which avoid the lower abdominal injuries to an occupant by removing that part of the steering wheel. That is to say, a split cone type configuration for the steering wheel has been achieved. This steering wheel is coupled to the dashboard directly and generally utilises electromagnetic rotation sensors to achieve a differential response for angle of rotation to approximate the normal left to right full wheel lock of a vehicle, and vice versa. Such a split cone configuration for the steering wheel thus only presents the front rim of the cone to the occupant for impact during a 5 collision.

Clearly, it is also desirable to provide an air bag in relation to this split cone type steering wheel configuration. The present invention relates to providing such an air bag arrangement.

I In accordance with the present invention there is provided an air bag arrangement for a motor vehicle, the arrangement comprises a split cone steering wheel associated at a mounting end with an air bag mechanism and configured to at least hinge about that mounting end relative to a dashboard and against a bias resisting inflation of an air bag from the air bag mechanism to confine that air bag to presentation from an end of the steering wheel opposed to the mounting end in accordance with a desired engagement regime with an occupant.

The bias may be provided by the steering wheel weight or spring load or torsional resistance about a hinge member between the steering wheel and the dashboard.

The air bag may comprise two sections such that the deployment regime involves first deployment prior to hinging about the mounting end towards an occupants legs/abdomen and subsequently after said first stage deployment and with hinging of the steering wheel about the dashboard, 5 deployment of the air bag towards an upper torso and head of that occupant.

Typically, the steering wheel straddles or saddles the air bag in order to confine the air bag under inflation to the desired deployment regime.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 is a pictorial symbolic illustration of an air bag arrangement prior to deployment; Figure 2 is pictorial symbolic illustration of an air bag at a first stage of deployment; and Figure 3 is a pictorial symbolic illustration of an air bag fully deployed 15 for engagement by an occupant.

Figure 1 illustrates in a pictorial symbolic representation, the fundamental elements of a steering wheel arrangement in accordance with the present invention. Thus, a steering wheel 1 which will be secured to a dashboard of a motor vehicle is associated with an air bag mechanism 2 and steering wheel orientation means 3.

The steering wheel 1 is of a split cone configuration such that a grip end 4 is presented to an occupant of a motor vehicle, whilst a mounting end 5 secures the steering wheel 1 to the dashboard. The steering wheel 1 will essentially deform with the dashboard in order to provide protection to an occupant.

1 It will be appreciated that previous steering wheels have been directly coupled to a vehicle chassis via the steering column. Thus, a relatively rigid structure has been located in front of the occupant. By use of the steering wheel 1 coupled directly to the dashboard and utilising electromagnetic sensors with appropriate control means to determine rotation of the steering wheel, it will be appreciated that this rigid structure in front of the occupant is removed.

In accordance with the present invention the essential guiding function provided by a guide tunnel 6 defined by the inner surface of the steering wheel 1 is utilised to present an air bag to an occupant in accordance with the desired regime. Clearly, the air bag mechanism is typically associated with the mounting end 5 of the steering wheel 1. Thus, the air bag will expand into the guide tunnel 6 and forward towards an occupant. It will 5- also be understood that, as with most steering wheels, the present steering wheel 1 is adjustable in terms of its angle of presentation and normally also adjustable with regard to the distance between the grip end 4 and the occupant. Thus, the air bag presented from the mechanism 2 is also similarly adjusted to provide the best presentation to the occupant in a vehicle collision.

The particular advantage with regard to split cone steering wheels such as steering wheel 1 is that the lower abdomen of an occupant is not exposed to contact with a relatively robust surface typical of a traditional steering wheel. However, it will be understood that during a motor vehicle collision, it is possible that the wheel 1 may be turned such that one side of the grip end 4 is adjacent that occupant's lower abdomen. In such circumstances, it will be appreciated that the orientation means 3 is arranged to return the steering wheel 1 to a balanced configuration with the grip end 4 substantially square and even with regard to presentation to the occupant.

Typically, the orientation means 3 will comprise respective pull wires 7, 8 coupled to retractor means arranged to pull these wires 7, 8 into a balanced state returning the steering wheel 1 to a centralised balanced condition or any other state determined least dangerous to an occupant.

Normally, this retractor mechanism will utilise a pyrotechnic device in order to achieve the necessary speed of operation.

As indicated above, the guide tunnel 6 defined by the steering wheel 1 is utilised in accordance with the present invention to present an air bag from the air bag mechanism 2 towards an occupant in the most appropriate deployment regime.

Figures 2 and 3 illustrate respectively the two principal stages of air bag deployment in accordance with the present invention. Essentially, in Figure 2, a lower half 10 of an air bag 9 is deployed through the steering wheel 1 via the guide tunnel 6 defined thereby. This lower half 10 of the air bag 9 is designed to engage the occupant's legs and abdomen in order to push that occupant back into their seat for most appropriate presentation to the full air bag when deployed.

The guide tunnel 6 in this deployment stage illustrated in Figure 2 ensures that air bag 9 inflation development is confined downwardly and therefore more specifically to the legs/lower abdomen area of an occupant.

It will be appreciated that without the guide tunnel 6 the air bag will typically radially expand and will not be focused towards the legs and abdomen in order to achieve the necessary urging of the occupant into the most appropriate state for full air bag 9 deployment.

Figure 3 illustrates the air bag 9 when fully deployed. Thus, a second part 11 of the air bag 9 has been inflated through opening of appropriate pressure level operable vents 12 between the first part 10 and the second part 11. This second part 11 engages an occupant's upper torso and head in order to protect them during a motor vehicle collision.

In accordance with the present invention, the guide tunnel 6 defined by 5 the steering wheel 1 in this fully deployed state has been hinged about the mounting end 5 in order to rotate in the direction of arrow head A and so reinforce the second part 11 in presentation to an occupant of a vehicle. Normally, this hinging about the end 5 with regard to a dashboard upon which the steering wheel 1 is secured only occurs upon deployment of the second part 11 of the air bag 9. However, it will be appreciated that specific air bag 9 deployment regimes may allow alternative movements of the steering wheel 1 about the mounting end 5 during an air bag deployment scenario. For example, the steering wheel 1 could hinge about the mounting end 5 towards the end of deployment of the first part 10 of the air bag 9 but before inflation of the second part 11. Alternatively, the steering wheel 1 could actually be forced downwardly in the opposite direction to arrow head A in order to further confine and compress the air bag as it is deployed through the guide tunnel 6 towards an occupant's legs and lower abdomen. Such downward pressure will further control and urge that occupant into its seating for better presentation to the air bag 9 when fully deployed.

A further feature with regard to hinging the steering wheel 1 about the mounting end 5 against the dashboard is that it lifts that steering wheel 1 upwards and therefore to a position less dangerous orientation with regard to an occupant.

Clearly, in order to provide the differential hinging about the mounting end 5 of the steering wheel 1 in accordance with the present invention, it is necessary to provide a bias within the steering wheel 1. This bias may be achieved through simply the weight of the steering wheel 1 or by 1 incorporating a spring loading mechanism or torsional response at the mounting end 5.

The effect of the bias is to ensure that the steering wheel 1 remains in place. Thus, the wheel 1 confines and guides the air bag 9 during its deployment regime until a sufficient force is created within that air bag 9 to act against the bias. Once the airbag 9 pressure or force is acting against the bias it will be understood that there will be hinging about the mounting end 5 of the steering wheel 1.

This force for wheel 1 hinging will generally be produced when the first part 10 of the air bag 9 is constricted between the occupant's legs/lower torso and the steering wheel 1 through its guide tunnel 6. With such constriction the pressure vents 12 will operate and open to begin deployment of the second part 11 of the air bag 9. However, there will be sufficient pressure force within the first part 10 to lift against the bias of the steering wheel 1 to hinge it about the mounting end 5.

As indicated above, a preferred regime for deployment of the air bag 9 is in a two-part format with a lower abdomen of the occupant constrained and urged towards a vehicle seat to ensure proper engagement with the second part 11 of the air bag 9. However, it will be appreciated that alternative multi-part air bags could be used in which different sequential deployments of relative parts of that air bag could occur in accordance with the desired regime for a particular installation within a vehicle.

It will be understood that, in accordance with the present invention, the steering wheel 1 through the guide tunnels essentially straddles the air bag 9 as it is deployed from the air bag mechanism 6 in order to confine it and reinforce it during appropriate stages of air bag deployment. Thus, although a split cone is defined as a preferred configuration for the steering wheel 1 and therefore guide tunnel 6, it will be appreciated that alternatively a rectangular open channel or half oval or split pyramidal configuration for the steering wheel 1 may also be acceptable in order to achieve the initial downward pressure bias to confine first part deployment of an air bag and reinforcement of a second part of that air bag when fully deployed through hinging about a mounting to a dashboard.

Normally, the second part 11 of the air bag 9 will be deployed in such a manner that it completely extends between the grip end 4 of the steering wheel 1 and a vehicle occupant in order to protect that occupant from contact with the steering wheel 1. Thus, the second part will typically "roll 5 over" the upper edge of the grip end 4.

Normally, the air bag 9 will, after deployment, deflate but the steering wheel 1 will be left in its upper hinge position in order to facilitate access to the occupant by emergency services and/or occupant exit from the vehicle.

Although depicted with the steering wheel 1 in a downturned configuration, it will be appreciated that alternatively the steering wheel 1 could be presented in an upturned configuration wherein the initial air bag deployment is confined between a guide tunnel defined by the steering wheel and the windscreen/roof of the vehicle. However, it will be appreciated, that with such an upturned configuration for a steering wheel, there is potential for forcing a grip end of that steering wheel downwards into an occupants lower abdomen and therefore precipitating injury. Consequently, an downturned configuration as indicated above is preferred.

It will be understood that the inner surface of the steering wheel may be made so that slip or grip between the air bag and wheel surface is facilitated. Thus, deployment may be alternatively controlled by grip engagement with the steering wheel surface for better guiding control or by slippage to ensure engagement between the deploying air bag and the steering wheel surface does not significantly slow the speed of such deployment.

1

Claims

-12CLAIMS

1. An air bag arrangement for a vehicle, the arrangement comprising a split steering wheel, such as a half cone, associated at a mounting end with an air bag mechanism and configured to at least hinge about that mounting end relative to a dashboard and against a bias resisting inflation of an air bag from the air bag mechanism to confine that air bag to presentation from an end of the steering wheel opposite the mounting end in accordance with a desired air bag deployment regime.

I

2. An arrangement as claimed in Claim 1, wherein the bias is provided by the steering wheel's own weight or a mechanical spring or a torsional response for the mounting end.

3. An arrangement as claimed in Claim 1 or Claim 2, wherein an air bag deployed from the air bag mechanism comprises a first part and a second part such that the desired air bag deployment regime comprises inflation of the first part without hinging of the steering wheel about the mounting end and therefore close confinement of that first part of the air bag whilst upon full inflation of that first part of the air bag, the second part of the air bag is deployed to engage an occupant and precipitate hinging of the steering wheel about the mounting end against the bias such that the second part of the air bag is reinforced by the steering wheel presentation to the occupant.

4. An arrangement as claimed in Claim 1, 2 or 3, wherein the steering wheel straddles or saddles the air bag as it is deployed from the air bag mechanism.

5. An arrangement as claimed in any preceding claim, wherein the split steering wheel cross-section defines a half circle or an open rectangle or an incomplete oval.

6. An air bag arrangement as claimed in any preceding claim, wherein the bias is configured to be retentive such that upon air bag deflation the steering wheel retains its position about its mounting end relative to the dashboard.

7. An air bag arrangement as substantially hereinbefore described with reference to the accompanying drawings.

8. A motor vehicle including an air bag arrangement as claimed in any preceding claim.