GB2341581A

GB2341581A - A steering wheel arrangement

Info

Publication number: GB2341581A
Application number: GB9920117A
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: GB9820337D0; GB9920117D0

Abstract

A steering wheel arrangement (1) in which a split cone steering wheel (2) is arranged to guide an air bag (15) upon deployment towards an occupant of a motor vehicle. The steering wheel (2) being associated with orientation means to ensure that the steering wheel is appropriately presented to that occupant in order both to guide the air bag (15) and reduce potential injury through engagement with an occupant's abdomen. The orientation means typically comprising pull wires (9, 11) secured to respective ends (5, 6) of a steering wheel (2) to bring that steering wheel (2) into balance. Typically, the air bag (15) upon full deployment will hinge the steering wheel (2) about its mounting end (4) away from the occupant in order to further diminish the potential for impact injury between the steering wheel (2) and that occupant.

Description

2341581 - 1 A STEERING WHEEL ARRANGEMENT The present invention relates to

a steering wheel arrangement and more particularly to a steering wheel arrangement which is safer in contact with an occupant of a vehicle during a collision.

Traditionally, steering. wheels have comprised a circle with spokes to mount that steering wheel to a steering column coupled to the steering mechanism of a vehicle. Unfortunately, the lower half of such a round steeringwheel tends to engage an vehicle occupant during a violent collision such that abdominal injuries are quite common.

More recently, an increasing number of motor vehicles have included air bag mechanisms deployed from the steering wheel in order to protect a vehicle occupant during a collision. However, even with an air bag it will be appreciated that the steering wheel is still relatively close to the occupant. Thus, the occupant may contact the lower part of the steering wheel before sufficient air bag deployment can occur to protect that occupant.

In view of the above problem, various solutions have been proposed to reduce the potential for occupant abdominal contact with the steering wheel during a collision. However, unless care is taken varying the steering wheel geometry can precipitate greater injury through unbalanced or more acute angular presentation of the steering wheel to an occupant.

Clearly, it is also advantageous in accordance with the current ethos to configure the steering wheel arrangement to best present an air bag, when deployed, to the occupant with the greatest protection.

It is an object of the present invention to provide a steering wheel arrangement which significantly avoids the above problems and also precipitates the significant occupant safety benefits during a vehicle collision.

In accordance with the present invention there is provided a steering wheel arrangement for a motor vehicle, the arrangement comprising a split cone steering wheel coupled to a dashboard assembly, the steering wheel being coupled to orientation means operable upon determination of a vehicle collision to present the steering vehicle within the vehicle relative to an occupant of that vehicle in order that an air bag can be deployed through a guide tunnel defined by the steering wheel and, where required, to ensure the steering wheel is generally presented to the occupant for less acute engagement with that occupant.

Typically, the steering wheel will be coupled to the dashboard in order to deform with that dashboard upon impact.

The split cone steering wheel may be configured to be presented to the occupant either upwardly or downwardly as required to achieve acceptable performance.

The orientation means may comprise respective pull wires secured to the extremities of the wheel in order to draw the wheel into balance and therefore presentation to the occupant for less acute engagement during a collision. Typically, the pull wires will be drawn using a pyrotechnic tensioner activated upon determination of a vehicle collision.

The bottom edges of the guide tunnel defined by the steering wheel may be inwardly lipped to further guide the air bag through interference engagement therewith. Furthermore, the air bag may include a recessed seam to co-operate with such bottom edges of the guide tunnel to further facilitate engagement.

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 perspective of a steering wheel arrangement prior to air bag deployment; Figure 2 is a pictorial front perspective of a steering wheel arrangement in a first or intermediate stage of air bag deployment; and Figure 3 is a pictorial front perspective of a steering wheel arrangement in a second or final stage of air bag deployment.

It will be appreciated that it is the lower half of a conventional steering wheel which violently abuts an occupant's abdomen during a motor vehicle collision. It is this lower half of the conventional steering wheel which therefore creates the abdomen injuries described above. In order to avoid this problem, it is possible to provide only partial circular ring steering wheels which do not include a lower half so dangerous to occupants during a vehicle collision. Unfortunately, the consequence of reducing a steering wheel rim from a circle is that it becomes difficult to secure with spokes or similar arrangements the steering wheel to the steering column.

In accordance with the present invention a steering wheel arrangement includes a split cone steering wheel which is mounted directly upon the vehicle dashboard. Thus, as illustrated in Figure 1, a steering wheel arrangement 1 comprises a split cone steering wheel 2 which is secured to a dashboardl This steering wheel 2 may be coupled at its mounting end 4 directly to a conventional steering column mechanism. However, it will be appreciated that more normally the steering wheel 2 will be coupled to electronic control mechanisms such that there is a differential response for rotation of the steering wheel 2 for angle of rotation. In such circumstances, the steering wheel 2 when rotated in the direction of arrow heads A, may provide limited turning of a vehicle's road wheels for the initial angular rotation range whilst radically increased road wheel turn, ie. exponentially, logarithmically or according to any other appropriate regime, for greater angles of rotation in the direction of arrow heads A of the steering wheel 2. Thus, the steering wheel 2 will never be completely rotated in order to provide the necessary vehicle road wheel turning from full lock left to full lock right or vice versa.

With the split cone steering wheel 2, it will be noted that there is no lower half to the wheel 2 which can engage an occupant's abdomen during a vehicle collision and so cause injury. In essence, each side of the wheel 2 respectively constitute a left grip 5 and a right grip 6 for the occupant's hands. Thus, the occupant can grip these ends 5, 6 in order to rotate the steering wheel 2 in the direction of arrow heads A and so precipitate vehicle road wheel turning.

Where the steering wheel 2 is coupled to wheel turning or steering mechanism through an electronic control arrangement, it will be appreciated that the steering wheel 2 can be directly mounted to the dashboard 3. In such circumstances, the whole dashboard 3 and the steering wheel 2 will deform together under impact in order to provide better protection to an occupant.

It will be appreciated that previous steering wheel mechanisms pass through apertures within the dashboard in order to be directly coupled to a mechanical steering mechanism typically mounted upon the vehicle chassis.

In such circumstances, it will be appreciated that the steering wheel presented a relatively rigid and inflexible obstacle directly in front of an occupant which is inherently is dangerous.

Coupling the steering wheel to the dashboard 3 allows the combined assembly to be relatively flexible and therefore absorb significant levels of occupant energy up to the limit of compression flexing, ie. component.

interference lock, etc._ Although the steering wheel arrangement, in accordance with the present invention with the split cone steering wheel 2 as described above, provides a significant reduction in direct steering wheel 2 contact with an occupant in a vehicle collision, it will be appreciated that air bag mechanisms will still be incorporated within a vehicle in order to protect an 20 occupant.

An air bag mechanism 7 is secured in its stowed configuration below the steering wheel 2 upon the dashboard 3. This position is essentially above the vehicle's pedals, ie. accelerator/brake. The air bag, when deployed from the mechanism 7, is propelled in the direction of arrow head B and guided by a guide tunnel constituted by the shape of the split cone steering wheel towards an occupant.

Clearly, a steering wheel 2 may be rotated in the direction of arrow head A at any position between the extremes of its angle of rotation during vehicle motion and more importantly during a vehicle collision. However, in order to provide the best coupling between the steering wheel 2 and an occupant, typically the steering wheel 2 should be balanced in terms of its contact with that occupant.

It will be noted in Figure 1 a broken line silhouette 8 of the steering wheel 2 is illustrated. This silhouette 8 extends down towards an occupant's abdomen so during a vehicle collision will potentially cause injury similar to a conventional steering wheel in that occupant's abdominal region. Clearly, the other side of the silhouette 8 is more raised than desired and therefore, as the steering wheel 2 is inclined towards the occupant, may present a delayed engagement with the occupant during the violence of a vehicle collision. In any event, presentation of the steering wheel 2 in the silhouette 8 configuration to an occupant would be essentially askew and dangerous.

In above askew circumstances, in accordance with the present invention, the steering wheel 2 is coupled through pull wires 9, 10 to a tensioner mechanism 11, which assembly constitutes orientation means for the steering wheel 2 and, when associated with the guide tunnel 14, for the air bag 15. The pull wires 9, 10 are secured to the ends 5, 6 such that upon tensioning through the tensioner mechanism 11 the steering wheel 2 is pulled back to a preferred presentation as depicted in solid line in Figure 1 to an occupant. This preferred presentation is not askew and is arranged to be above the abdominal region of that occupant.

Normally, the tensioner mechanism 11 will include a pyrotechnic device 12 which pulls against a pulley mechanism 13 in order to balance the lengths of respective pull wires 9, 11 consistent with the solid line presentation of the steering wheel 2 as depicted in Figure 1. Clearly, a pyrotechnic device 12 is used with regard to the tensioner mechanism 11 in order to provide the necessary rapidity of response during a vehicle collision.

The air bag mechanism 7 will generally only deploy into the guide tunnel 14 defined by the steering wheel 2 when that steering wheel 2 is in the solid line configuration of best or preferred presentation to a vehicle occupant during a vehicle collision. Thus, the pull wires 9, 10 will be balanced and normally of equal length from the pulley mechanism 13, but more importantly such that the ends 5, 6 are "square" to an occupant.

It will be understood, if the steering wheel 2 was askew as described previously with regard to silhouette 8, that the air bag deployed from the mechanism 7 itself may be twisted and inappropriately presented to the occupant. Alternatively, it will be appreciated in the same circumstances, the steering wheel 2 may be deliberately oriented askew for best engagement with the occupant.

Figures 2 and 3 illustrate in pictorial front perspective, two stages of air bag deployment in a steering wheel arrangement in accordance with the present invention. In Figure 2, an air bag 15 is deployed from the air bag mechanism 7 upwardly through the guide tunnel 14 defined by the steering wheel 2 towards an occupant (not shown). The air bag 15 during its deployment episode is essentially guided towards an occupant (not shown) through interference engagement and confinement within the guide tunnel 14 defined by the steering wheel 2.

It will be noted that the guide tunnel 14 confines and partially envelopes a portion of the air bag 50 to constrain lateral movement in order to cause directional presentation towards the occupant in the direction of arrow head B. In such circumstances, the air bag 15 is presented upon deployment in a slightly upward orientation with the bottom of the air bag 15 relatively free to expand and so protect the occupant's abdomen.

Normally, the steering wheel 2 will be at an approximate angle of 170" to the dashboard 3. However, in accordance with the present invention, it will be appreciated that the steering wheel 2 angle is adjustable as is conventional with steering wheels. Thus, the angle of presentation of the steering wheel 2 to an occupant can be varied in accordance with occupant discretion. In such circumstances, it will be appreciated that the guide tunnel 14 constituted by the steering wheel 2 is thereby adjustable to present the air bag 15 upon deployment most appropriately to that occupant. Thus, if the occupant is relatively short and the steering wheel 2 is therefore configured appropriately, an angle a between the dashboard 3 and the steering wheel 2 may be significantly greater than 170" whilst with a taller occupant the angle g may be less than 170, but in either event, the guiding tunnel 14 will be adjusted appropriately to present the air bag 15 accordingly upon deployment to that occupant.

A further feature of the guide tunnel 14 is that upon initial and subsequent engagement with an occupant, the effect of interference between the tunnel 14 and the air bag 15 is to retain that air bag's 15 orientation to the occupant. Thus, lateral or glance deflection of the air bag 15 either side of the occupant is resisted through the engagement between the tunnel 14 and the air bag 15.

Clearly, the steering wheel 2 remains a relatively hard and narrow engagement front with an occupant which can precipitate injury even though that steering wheel 2 may be coupled deformably to the dashboard 3 and protection of the air bag 15 is provided when deployed. Thus, in Figure 3, it is illustrated that the final deployment stage of the air bag 15 is to essentially lift the steering wheel 2 upwards and away from an occupant engaged by a front surface of the air bag 15.

Clearly, as the steering wheel 2 is lifted upwardly by the air bag 15 in the final stages of air bag deployment, the angle 1 between that steering wheel 2 and the dashboard 3 is reduced, ie. from a conventional 170 to a final deployed state of 140. Thus, the steering wheel 2 presents a less acute engagement surface to the occupant with this reduced angle a.

In order to further facilitate interference engagement and a confinement between the steering wheel 2 when defining the guiding tunnel 14, it is typical for bottom edges running from the ends 5, 6 to the mounting end 4 to incorporate inwardly facing lips. These inwardly facing lips essentially provide a deformation resistance to the air bag 15 as it inflates 20 under deployment to grip that air bag and therefore hold the air bag 15 on 12- line. To further enhance this interference effect between inwardly facing lips of the guide tunnel 14, it will be appreciated that recessed seams which are co-operative with these lipped edges, may be provided in the air bag 15.

Clearly, in addition to providing inwardly facing lips along the edges between the ends 5, 6 and the mounting end 4, similar grip protrusions into or recesses outwards from the inner surface of the guide tunnel 14 may be provided in order to grip the air bag 15 under deployment scenario and so resist lateral movement of the air bag out of alignment. In either event, it will be appreciated that the grip between the air bag 15 and the guide tunnel 14 constituted by the steering wheel 2 will be of a relatively low strength and certainly of insufficient resilience to precipitate air bag 15 rupture.

Normally, it will be appreciated that the steering wheel 2 will be presented as depicted in Figures 1, 2 and 3 in a downward arched or domed configuration in order to confine the air bag 15 upon deployment between the guide tunnel 14 and the occupant particularly through that occupant's lower abdomen and leg. However, it will also be understood that the present invention includes the possibility to present a steering wheel in an upturned U or dished configuration where the air bag is guided from below and so the air bag is unfettered to develop in front of the occupant between that occupant's upper torso and a vehicle windscreen. However, it will be clearly understood in such a downturned configuration that the benefits of occupant lower abdomen avoidance is removed.

As indicated above, typically the steering wheel 2 is hinged about its mounting end 4 upon the dashboard 3 through deployment of the air bag 15.

In such circumstances, it will be appreciated that after a suitable degree of hinge rotation about the mounting end 4, the steering wheel 2 may be arranged to detach from the dashboard 3 further removing it from potential impact with an occupant.

I Typically, the steering wheel 2 will have a generally half round end 10 tapering into the cone as illustrated and described above. However, it will be appreciated that this split cone shape for the steering wheel 2 can incorporate apertures to accept an occupant's fingers to grip the ends 5, 6 along with aesthetic and structural features as required by a vehicle designer. For example, the cone could be arranged to concertina towards and away from the dashboard 3 to provide the occupant with a range of driving positions in.addition hinge rotation about the mounting end 4 to give various angular presentations of the ends 5, 6 to that occupant.

For the purposes of this invention, it will be appreciated that the term c(split cone" includes most channel or grooved shapes including rectangular, oval, etc. Furthermore, these shapes normally taper, as with a cone, to a mounting end upon the dashboard in order to provide expansive guiding in the guide tunnel defined by the steering wheel.

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Claims

- 15CLAIMS

1. A steering wheel arrangement for a vehicle, the arrangement comprising a split cone steering wheel coupled to a dashboard assembly, said steering wheel being coupled to orientation means operable upon determination of a vehicle collision to present the steering wheel within the vehicle relative to an occupant of that vehicle in order that an air bag can be deployed through a guide tunnel defined by the steering wheel towards that occupant.

2. An arrangement as claimed in Claim 1, wherein the steering wheel is directly coupled to the dashboard to deform therewith upon impact with an occupant of the vehicle.

3. An arrangement as claimed in Claim 1 or Claim 2, wherein the steering wheel is arranged to be configured in a downward or domed configuration relative to an occupant.

4. An arrangement as claimed in Claim 1 or Claim 2, wherein the steering wheel is arranged to be configured in an upward or dish configuration relative to an occupant in a vehicle.

5. An arrangement as claimed in any preceding claim, wherein the orientation means comprises pull wires secured to respective ends of the wheel to draw that wheel into a less acute engagement with the occupant upon detection of a vehicle collision.

6. An arrangement as claimed in Claim 5, wherein the pull wires are drawn into balance using a pyrotechnic tensioner.

7. An arrangement as claimed in any preceding claim, wherein bottom edges between steering wheel ends for gripping by an occupant and a mount end of the steering wheel incorporate inwardly facing lips to guide the air bag upon deployment through interference engagement.

8. An arrangement as claimed in Claim 7, wherein the air bag includes reciprocal recessed seams to facilitate engagement with the inwardly facing lips of the guide tunnel to facilitate further interference engagement and so guiding between the air bag and the guide tunnel.

9. An arrangement as claimed in any preceding claim, wherein the guide tunnel includes protrusions or recesses to facilitate guiding between the guide tunnel and the air bag upon deployment towards an occupant of a vehicle.

10. A steering wheel arrangement substantially as hereinbefore described with reference to the accompanying drawings.

11. A motor vehicle including a steering wheel arrangement in accordance with any preceding claim.

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