GB2336572A - A vehicle bumper with an air bag - Google Patents

Abstract

The vehicle bumper 1 has a bumper protrusion 3 and an air bag mechanism 4 that can deploy an air bag 6 below the bumper in the event of a collision. The air bag in combination with the protrusion presents a larger surface extending from a lower level and this acts to protect a pedestrian's leg 7 from bending during a collision. On deployment of the air bag a lead surface 8 of the bumper protrusion and a front surface of the bag align to provide a consistent collision plane CP. To detect a collision or when one may occur the bumper has or is connected to sensor means which determine when to deploy the bag. Typically, several air bags 6 are provided that, when deployed, constitute a composite barrier below the bumper protrusion 3. The bumper is particularly suitable to high riding 4x4 off - road vehicles as the vehicle retains a sufficient ground clearance necessary to avoid contact with rough terrain when the bag is not deployed but in the event of a collision the bumper provides a broad surface extending from a low height.

Description

2336572 A VEHICLE AIR BAG BUMPER The present invention relates to a

vehicle air bag bumper for pedestrian safety and more particularly to pedestrian safety with regard to frontal impact with road vehicles.

There is an inherent requirement to continuously improve motor vehicle safety both in terms of vehicle -to -vehicle collisions and with regard to vehicle -pe de strian collisions. The present invention relates particularly to collisions between a vehicle, and more especially offroad 4x4 vehicles, with a pedestrian.

It will be noted that off road vehicles generally have a high ground clearance and approach angle in order to avoid so-called grounding between the vehicles and the uneven surface upon which they are driven.

Such high approach angles for an off road vehicle inherently presents the bumper or fender of that vehicle at a relatively high position upon a pedestrian leg. Thus, when subjected to a coWsion, that pedestrian's leg is bent in an unacceptable manner. It will be appreciated that any collision between a motor vehicle and a pedestrian will injure that pedestrian. However, by control of the nature of the impact and deformation of the pedestrian, the severity of such injury can be reduced. Typically, acceptable levels of performance are proposed by appropriate regulatory authorities through pedestrian safety legislation. Thus, for example, there may be a limit to the angle of bend between the upper and lower halves of a pedestrian's leg in the order of 1W as determined by a test impacter propelled at the front of a motor vehicle at a predetermined velocity, ie. 40 kph.

A high riding off-road vehicle has difficulty achieving such a level of pedestrian impact safety due to the high point of contact with the pedestrian's leg. A solution to this problem is to provide a bumper contact area for collision with a pedestrian at a lower level in order to reduce the knee bending angle to an acceptable degree. Unfortunately, with an off road vehicle, it is necessary to retain the approach angle and ground clearance necessary to avoid contact with rough terrain.

In addition to providing a lower contact surface for acceptable pedestrian leg impact performance, it will be appreciated that energy must be absorbed through such a bumper arrangement and thus somewhere in the order of 80 to 100 mm of bumper deformation is required. Furthermore, in an off road vehicle, it will generally be necessary to ensure that there is an approach angle for the bumper in the order of 40 whilst in an on road, highway situation, the approach angle should be in the order of 15.

-3 1 It will be appreciated by those skilled in the art that over recent years there has been an increase in the use of notionally off road or 4x4 type vehicles for normal highway use. Furthermore, it will be appreciated that due to the indeterminate nature of where contact will take place, it is necessary that the full width of the vehicle is presented for contact in a collision with a pedestrian.

It will be understood that modern vehicles include a bumper or fender made from a metal or plastics material which may be sufficiently deformable to absorb pedestrian collision energy when in contact therewith.

It is an object of the present invention to improve pedestrian safety during a collision through an appropriate vehicle bumper to limit the leg bend in such a collision.

In accordance with the present invention there is provided a vehicle air bag bumper comprising a bumper protrusion having an engagement surface and incorporating an air bag mechanism coupled to sensor means arranged to deploy said air bag mechanism in response to a collision with said bumper protrusion in order to present an air bag below said bumper protrusion and so supplement the engagement surface for contact with a pedestrian's leg during such collision.

Preferably, the air bag upon deployment provides a surface consistent with a collision plane which extends perpendicularly from the engagement surface of said bumper protrusion.

The air bag mechanism may comprise a plurality of individual air bag 5 elements to constitute a composite barrier below the bumper protrusion.

The air bag mechanism may utilise existing structural shape within the motor vehicle in order to provide a transiently resistive barrier to collision with a pedestrian's leg.

An embodiment of the present invention will now be described by way 10 of example only with reference to the accompanying drawings, in which:

Figure 1 is a schematic side elevation of a vehicle air bag bumper during normal, driving operation of a motor vehicle; and Figure 2 is a schematic side elevation of the vehicle air bag bumper depicted in Figure 1 in a deployed for collision configuration.

As indicated above, in order to diminish injury to a pedestrian's leg, it is desirable to present a broad contact surface to that pedestrian's leg during a collision and such that the contact surface extends from a relatively low position upon the pedestrian's leg. Unfortunately, most vehicle bumpers, particularly with regard to so-called off road vehicles, are at a significant height relative to a pedestrian's leg. Such height is to provide sufficient approach angle and clearance for travel over rough terrain. Figure 1 illustrates a vehicle bumper 1 in its normal operational state for driving whilst Figure 2 illustrates the vehicle bumper 1 in a deployed state just prior to or during a collision.

Referring to Figure 1, a motor vehicle 2 includes a vehicle air bag bumper 1 along its front surface. This bumper 1 comprises a bumper protrusion 3 and an air bag mechanism 4. The bumper 1 is provided to protect the vehicle 2 body panels from inadvertent deformation and denting, etc. Furthermore, te- vehicle 2 has an approach angle profile shown by dotted line A-A sufficient for expected ground clearance of obstacles, etc. as the vehicle 2 is driven along, particularly in rough off-road terrain.

As a consequence of providing sufficient approach angle and ground clearance, the bumper 1 is at a relatively high elevation and so will contact any pedestrian at that elevation. Unfortunately, with regard to a pedestrian and in particular their leg, such a high contact point upon a pedestrian's leg will present unacceptable bend and so increased injury to the pedestrian. It will be understood that the pedestrian's leg will essentially bend about the point of narrow contact with a pedestrian's knee presented by the bumper 1. Thus, in accordance with the present invention, - 6 the area below the bumper protrusion 3 during a collision with a pedestrian is filled with an air bag deployed from the air bag mechanism 4. As the air bag is only deployed when required, it will be appreciated that the approach angle A-A and ground clearance for the vehicle 2 is not diminished during off-road vehicle operation. Such retention of approach angle A-A and ground clearance is required with regard to off road vehicles.

Figure 2 illustrates the bumper 1 in schematic side elevation with an air bag 6 deployed from the air bag mechanism 4. During a collision a pedestrian leg 7 will be subjected to percussive collision forces F. Thus, in accordance with the present invention, it will be appreciated that application of the percussive force F is spread over a broader contact band defined by a leading engagement surface 8 of the protrusion 3 and a frontal surface of the air bag 6. In such circumstances, the leg 7 is less likely to bend and so injury should be reduced as a result of collision impact with the vehicle 2 through its bumper 1.

It will be understood that the air bag mechanism 4 will rapidly deploy the air bag 6 in order to provide a relatively consistent collision plane CP in combination with the protrusion 3. However, it will be understood that the vehicle bumper 1 must include or be connected to a sensor device to determine when the air bag 6 should be deployed. This sensor device may determine when collision occurs or, possibly, when a sufficiently violent deceleration of the vehicle 2 is undertaken to indicate that there is a collision taking place. Such sensor device may use similar sensors to those used for occupant airbags within the vehicle or, preferably, utilise radar detection of a pedestrian and calculation from vehicle speed proximity, etc, to determine whether a collision will occur.

It is important that air bag deployment takes place rapidly but also that there is not additional pedestrian injury due to such deployment upon the pedestrian's leg 7. Thus, the air bag 6 should generally stay within the confines of the collision plane CP which extends perpendicularly from the lead, engagement surface 8 of the bumper protrusion 3.

The air bag 6 may be deployed as depicted in Figure 2 in a downward direction or, by appropriate location of the air bag mechanism 4, forwardly towards the collision plane CP.

Typically, several air bags 6 in alignment will be provided to constitute a composite barrier below the bumper protrusion 3 in order to protect a pedestrian leg 7 from unacceptable bending. Thus, the contact surface during collision will extend substantially across the width of the vehicle 2 and comprise the bumper protrusion 3 and associated air bags 6. Those skilled in the art will understand that air bag mechanisms are well known -8 and that a generally conventional air bag will achieve the desired performance in accordance with the present invention.

Essentially, air bags are deployed by firing a pyrotechnic gas-producing charge to rapidly fill and expand the air bag to a deployed state.

Transiently, the air bag is relatively stiff and strong due to the pressurised gas held within. However, by their nature the gas is only transiently contained and so susceptible to deformation under percussive load. In order to supplement such transient stiú1hess necessary to protect a pedestrian's 2 leg 7, air bag 6 will normally engage structural features such as a valence surface 10 in order to resist rearward deformation of the air bag 6 upon contact with the leg 7. However, it will be appreciated that the air bag 6 will stffi deform in order to absorb collision energy from the leg 7.

Similarly, the vehicle 2 may, in accordance with its already existing crumple zones and other energy absorption features, deform in order to accommodate collision energy in the safest manner possible. Thus, the vehicle bumper 1 will be made from a deformable material which can reciprocally deform with the vehicle 2 as collision energy is dissipated through crumple zone deformation, etc, particularly when in contact with another vehicle or substantial stationary object such as a tree.

1 It will be understood to further extend upwards the collision plane CP with a pedestrian, further fixed protrusions 100 could be added to a vehicle with a surface consistent with the collision plane CP.

Claims (7)

1 1. A vehicle bumper comprising a bumper protrusion having an engagement surface and incorporating an air bag mechanism coupled to sensor means arranged to deploy said air bag mechanism in response to a collision with said bumper protrusion in order to present said air bag below said bumper protrusion to supplement the engagement surface for contact with a pedestrian's leg during such a collision.

A bumper as claimed in Claim 1, wherein the air bag upon deployment, provides a surface consistent with a collision plane which extends perpendicularly from below the engagement surface of said bumper protrusion.

3. A bumper as claimed in Claim 1 or Claim 2, wherein the air bag mechanism is arranged to deploy a plurality of individual air bag elements to constitute a composite barrier below the bumper protrusion.

4. A bumper as claimed in any of Claims 1, 2 or 3, wherein the air bag is deployed in a downward direction from the bumper protrusion.

5. A bumper as claimed in any of Claims 1 to 3, wherein the air bag is deployed in a forward direction.

6. A vehicle bumper substantially as hereinbefore described with reference to the accompanying drawing.

7. A motor vehicle including a vehicle bumper in accordance with any preceding claim.