Bumper assembly for a vehicle

Abstract

Aspects of the present invention relate to a bumper assembly (10, figure 1) for a vehicle (1000, figure 8) and a vehicle. The bumper assembly comprising: a bumper (12) comprising an upper portion 14 a

Description

TECHNICAL FIELD The present disclosure relates to a bumper assembly for a vehicle. In particular, a bumper assembly comprising an air bag for deployment in an impact event. Aspects of the invention relate to a bumper assembly for a vehicle, and to a vehicle. BACKGROUND It is known to provide vehicles designed for off road driving with a ground clearance and approach angle that are greater than the ground clearance and approach angle of a vehicle designed solely for on road driving. During an impact event between an object and the vehicle, how the object interacts which the vehicle will depend on the approach angle and ground clearance of the vehicle. In vehicles designed for both on and off road driving, it is known to have a ride height of the vehicle that is adjustable between a higher ride height and a lower ride height. The higher ride height is intended for off road driving and the lower ride height is intended for on road driving. At the higher ride height, the ground clearance of the vehicle is greater compared to the lower ride height. Additionally, at the higher ride height, the approach angle of the vehicle is typically also greater compared to the approach angle of the vehicle in the lower ride height so that the off road driving capabilities of the vehicle are improved. During an impact event between an object and the vehicle designed for both on and off road driving, the object will interact differently with the vehicle depending on whether the vehicle is in the higher or lower ride height due to the differing approach angles and heights of the vehicle. It is an aim of the present invention to provide a bumper assembly which improves the support provided to an object during an impact event. In particular, it is an aim of the present invention to provide a bumper assembly which improves the support provided to an object during an impact event when the approach angle and ground clearance of vehicle is configured to off road driving. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a bumper assembly for a vehicle, and a vehicle as claimed in the appended claims. According to an aspect of the invention, there is provided a bumper assembly for a vehicle. The bumper assembly comprising: a bumper; and an air bag for deployment during an impact event with an object; wherein, upon deployment, the air bag is configured to be compressed between an object and the bumper such that the air bag is configured to support an object as the object rotates beneath the bumper assembly during an impact event. According to an aspect of the invention, there is provided a bumper assembly for a vehicle. The bumper assembly comprising: a bumper comprising an upper portion and a lower portion; and an air bag for deployment during an impact event with an object; wherein the upper portion comprises a support surface for contacting an object during an impact event; wherein the lower portion of the bumper comprises an outer surface that is inclined relative to the support surface; and wherein, upon deployment, the air bag is configured to be compressed between an object and the outer surface of the lower portion of the bumper such that the air bag is configured to support an object as the object rotates beneath the bumper assembly during an impact event. In either of the above-described aspects of the invention, when the air bag is deployed, the air bag effectively increases the vertical extent of the bumper thereby decreasing the distance between the bumper assembly and the ground. In a vehicle configured for off road driving, the air bag may effectively fill a space below the bumper that was created when increasing the approach angle and / or ground clearance of the vehicle for off road driving. During an impact event of a vehicle and an object, the object engages with the air bag rather than the inclined outer surface of the lower portion of the bumper as it rotates beneath the bumper assembly. The air bag consequently improves the support provided to be object an object as it rotates beneath the bumper and also limits the amount of rotation that occurs during an impact event. Reducing the amount of rotation beneath the bumper assembly and providing support as an object rotates beneath the bumper assembly is particularly advantageous when the object is a lower limb of a pedestrian. In certain embodiments, upon deployment, a portion of the surface of the air bag is rearward of the support surface and spaced apart from the ground to support an object as the object rotates beneath the bumper assembly during an impact event. The portion of the surface of the air bag that is rearward of the support surface and spaced apart from the ground provides a support surface for the object as it rotates beneath the bumper assembly during an impact event. Upon deployment, a lowermost part of the air bag may be spaced apart from the ground. The air bag may be deployable from a position on the bumper that is below and rearwards of the support surface of the upper portion of the bumper. This position of deployment may improve the ease of comprising the air bag between an object and the outer surface of the lower portion of the bumper during the impact event thereby improving the support to the object provided by the air bag. The lower bumper may comprise the air bag and the air bag is deployable from the outer surface of lower portion of the bumper. As such, compression of the air bag between an object and the outer surface of the lower portion of the bumper in an impact event may be improved thereby improving the support provided to the object in an impact event. Optionally, the lower portion of the bumper may comprise a recess in the outer surface and the air bag is stowed in the recess. As such, the air bag may not affect the approach angle of a vehicle on which the bumper assembly is installed. The bumper assembly may comprise a detachable cover arranged to cover the recess. The cover may keep the air bag safe from damage due to debris and provides clean surface to vehicle. The bumper assembly may comprise an air bag assembly. The air bag assembly may comprise the air bag. The air bag assembly may be arranged to deploy the air bag in a direction substantially perpendicular to the outer surface of the lower portion of the bumper. Deploying the air bag in this way may help the air bag to provide support for an object both below and in front of the lower portion of the bumper thereby improving the support provided to the object in an impact event. The air bag assembly may comprise a control system configured to deploy the air bag in a direction substantially perpendicular to the outer surface of the lower portion of the bumper. The air bag may be configured to cover the outer surface of the lower portion of the bumper upon deployment. As such, the object may be supported across the entire surface of the lower portion of the bumper during an impact event. The outer surface of the lower portion of the bumper may extend from the support surface of the upper portion of the bumper in a rearwards direction. Having the outer surface of the lower portion of the bumper adjoin the support surface of the upper portion of the bumper and having the air bag cover the outer surface upon deployment ensures that there is no gap between support surface and air bag during an impact event thereby improving the support provided to an object. The outer surface of the lower portion of the bumper may be inclined relative to the support surface of the upper portion of the bumper such that an angle from the support surface to the outer surface is in a range from 210 degrees to 240 degrees. The outer surface of the lower portion of the bumper may be consistent with and not limit the approach angle of a vehicle. The approach angle of the vehicle may be in a range from 30 to 60 degrees. The support surface of the upper portion of the bumper may define a contact plane and, upon deployment, a portion of a surface of the air bag may reside substantially in the contact plane to provide an extension to the support surface in the contact plane. The air bag provides support by increasing the extent of the bumper in the contact plane. This may reduce the amount by which the object rotates under the bumper during an impact event which may be particularly advantageous when the object is a lower limb of a pedestrian. The air bag may provide one support surface for the object in the contact plane and another support surface for the object when it rotates beneath the bumper assembly. The air bag may be configured such that, upon deployment, the air bag does not extend beyond the contact plane in a forwards direction. The air bag therefore may not provide a force on the object that extends beyond the contact plane during an impact event. The contact plane may be substantially perpendicular to the ground when the bumper assembly is attached to a vehicle. As such, the air bag may increase vertical support provided to an object during an impact event. In certain embodiments, upon deployment the air bag is configured to reduce the height of the bumper by up to 190 mm or up to 170 mm. As such, the air bag supports the object as it rotates beneath the bumper but the air bag may not contact the ground beneath the vehicle. In certain embodiments, the bumper assembly comprises a controller comprising one or more processors collectively for controlling deployment of the air bag. In certain embodiments, the bumper assembly may be for a vehicle having first and second ride heights, wherein the second ride height is higher than the first ride height. The bumper assembly may comprise: a bumper comprising a first support surface for contacting an object during an impact event; and an air bag assembly comprising an air bag for deployment during an impact event with an object, the air bag being configured to provide a second support surface for contacting an object during an impact event collision upon deployment; and the one or more processors of the controller may be collectively configured to: receive a ride height signal indicative of a current ride height; control deployment of the air bag in dependence on the ride height signal such that the air bag is deployable if the current ride height is the second ride height and deployment of the air bag is prevented if the current ride height is the first ride height. Deploying the air bag when the vehicle is in the second, higher ride height and not when the vehicle is in the first, lower ride height prevents air bag being deploying when it is not needed. When the vehicle is in the lower ride height, the first support surface of the bumper provides sufficient support for the object during an impact event. As such, the air bag does not need to be deployed when the vehicle is in the first ride height. Preventing deployment of the air bag when it is not necessary is advantageous as it removes the need to replace the air bag after an unnecessary deployment. When the vehicle is in the second ride height, the air bag may be deployed during an impact event to effectively fill a space below the bumper that was created when raising the vehicle in height from the first to the second ride height. The air bag improves the support provided by the bumper assembly to the object during an impact event. The support provided by the air bag may be particularly advantageous when the object is the lower limb of a pedestrian. In certain embodiments, the one or more processors of the controller may be collectively configured to: receive a vehicle speed signal indicative of a current vehicle speed; control deployment of the air bag in dependence on the ride height signal and the vehicle speed signal such that: the air bag is deployable if the current ride height is the second ride height and the current vehicle speed is at or above a lower vehicle speed threshold; and deployment of the air bag is prevented if the current ride height is the first ride height or the current vehicle speed is below the lower vehicle speed threshold. The air bag therefore will not be deployed during impact events at low speeds, for example during an impact event which occurs when parking the vehicle, when the support provided by the air bag is not needed. As such, unnecessary deployment of the air bag may be prevented. The lower vehicle speed threshold may be from 3 to 8 km / h or wherein the lower vehicle speed threshold is 5 km / h. The lower vehicle speed threshold may correspond to the typical vehicle speed used when manoeuvring to park the vehicle and may be less that the walking speed of a pedestrian. In certain embodiments, the bumper assembly may comprise: a sensor configured to: detect an impact event between the bumper and an object; and output a detection signal in response to detection of an impact event; wherein, to control deployment of the air bag, the one or more processors of the controller may be collectively configured to: receive the detection signal; determine the existence of an impact event based on the detection signal; and in response to determining the existence of an impact event, output a deployment signal to the air bag assembly to deploy the air bag if the current ride height is the second ride height or prevent output of the deployment signal is prevented if the current ride height is the first ride height. The sensor provides simply yet effective way of detecting impact events and causing deployment of the air bag when the support provided by the air bag is advantageous. The sensor may prevent the air bag being deployed, for example, in response to rapid braking of the vehicle when there is no impact event. In certain embodiments, in response to determining the existence of an impact event, the one or more processors of the controller may be configured to output a deployment signal to the air bag assembly to deploy the air bag if the current ride height is the second ride height and prevent output of the deployment signal if the current ride height is the first ride height. In certain embodiments, in response to determining the existence of an impact event, the one or more processors of the controller may be configured to output a deployment signal to the air bag assembly to deploy the air bag if the current ride height is the second ride height and the current vehicle speed is at or above a lower vehicle speed threshold and prevent output of the deployment signal if the current ride height is the first ride height or the current vehicle speed is below the lower vehicle speed threshold. Therefore, even if the existence of an impact event is determined, the air bag therefore will not be deployed if the vehicle is travelling at a low speed or is in the first ride height where the support provided by the air bag is not needed. As such, unnecessary deployment of the air bag may be prevented. In certain embodiments, the first support surface may be configured to deform during an impact event; and wherein the sensor is configured to detect deformation of the first support surface and output the detection signal in response to said deformation. Deploying the air bag once deformation of the bumper has occurred (i.e. after the onset of an impact event) may ensure that the air bag is only deployed during an impact event and may prevent the air bag being deploying when it is not needed, such as during offroad driving on uneven surfaces such as through sand dunes. Deploying the air bag after the object has made contact with the may improve the support the air bag provides for the object as it rotates beneath the bumper assembly due to the sequence with which the object interacts with the parts of the bumper assembly and the timing of deployment of the air bag. Deployment of the air bag after the onset of an impact event may be particularly advantageous when the object is a lower limb of a pedestrian. The sensor may be positioned behind the first support surface. The position of the sensor may ensure that the sensor only detects an impact event once deformation of the first support surface has occurred. Optionally, the sensor may be positioned from 1 cm to 3 cm behind the first engagement surface. This position of the sensor may help ensure that the air bag is only deployed once deformation of the first support surface has occurred whilst also preventing undue delay in the deployment of the air bag thereby improve the support of the object during an impact event. Optionally, the sensor may be positioned at or near the top of the first support surface. This position of the sensor may reduce risk of air bag being deployed during impact events where the support of the air bag is not needed. For example, during impact events is objects that are close to the ground. In certain embodiments, the sensor may comprise at least two sensors spaced apart across the first support surface or the sensor may extend substantially across the width of the first support surface. As such, detection of impact events over the breath of the first support surface may be improved. Optionally, the sensor may comprise a pressure sensor. A pressure sensor positioned behind the first support surface may provide a simple yet effect way to detect deformation of the first support surface. According to an aspect of the invention, there is provided a vehicle comprising the above-described bumper assembly. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a schematic representation of a bumper assembly according to an embodiment of the invention; Figure 2 shows a schematic representation of an air bag assembly for use in the bumper assembly of Figure 1; Figure 3 shows a side view of the bumper assembly of Figure 1; Figures 4A and 4B shows the bumper assembly of Figure 1 during an impact event; Figures 5A and 5B shows the bumper assembly of Figure 1 during an impact event; Figures 6A and 6B shows the bumper assembly of Figure 1 during an impact event; Figure 7 shows a schematic representation of a controller of the bumper assembly of Figure 1; and Figure 8 shows a vehicle in accordance with an embodiment of the invention. DETAILED DESCRIPTION Figure 1 shows a bumper assembly 10 for a vehicle 1000 according to an embodiment of the invention. Figure 8 shows a vehicle 1000 comprising the bumper assembly 10 of Figure 1. The bumper assembly 10 comprises a bumper 12. As shown in the embodiment in the Figures, the bumper 12 may be a front bumper 12 of the vehicle 1000. The bumper 12 comprises an upper portion 14 and a lower portion 16. As shown in the Figures, the upper portion 14 is above the lower portion 16 relative to the ground on which the vehicle 1000 stands when the bumper assembly 10 is attached to the vehicle 1000. The lower portion 16 of the bumper 12 may act as a bash-plate for the vehicle 1000. The upper portion 14 of the bumper 12 may be between the lower portion 16 of the bumper 12 and a bonnet 1005 of the vehicle 1000. As shown in the embodiment in the Figures, the upper portion 14 of the bumper 12 may extend vertically from the lower portion 16 of the bumper 12 to the bonnet 1005. Upper portion 14 of bumper 12 may extend laterally substantially across the width of the vehicle 1000. As shown in the embodiment in the Figures, the upper portion 14 of the bumper 12 may comprise at least one panel 18. As shown in the embodiment in the Figures, the upper portion 14 of the bumper 12 may comprise a plurality of panels 18. Each panel 18 may be planar or curved (e.g. convex in shape), or each panel 18 may comprise a combination of planar and curved sections. The upper portion 14 of the bumper 12 may comprise one or more grilles 20. Each grille 20 may cover an opening behind the bumper 12 to allow air to enter or exit the vehicle 1000. In the embodiment shown in the Figures, the upper portion 14 of the bumper 12 comprises two grilles 20. The upper portion 14 of the bumper 12 comprises a support surface or first support surface 22. The first support surface 22 is for contacting an object 23 during an impact event. The first support surface 22 may provide support for the object 23 during an impact event. The object 23 may be any object 23 that the vehicle 1000 could come into contact during an impact event. The object 23 may, for example, be a lower limb of a pedestrian. The panels 18 and grilles 20 of the upper portion 14 of the bumper 12 provide the first support surface 22. The first support surface 22 may be defined by an outer surface 28 or a part of the outer surface 28 of the upper portion 14 of the bumper 12. As shown in the embodiment tin the Figures, the first support surface 22 may be substantially vertical. The first support surface 22 may extend laterally from one of the headlights 1006 of the vehicle 1000 to the other headlight 1006 of the vehicle 1000. The vertical extend of the first support surface 22 may be from the lower portion 16 of the bumper 12 to the bonnet 1005. The extend of the first support surface 24 may therefore be less than the extend of the upper portion 14 of the bumper 12. The first support surface 22 of the upper portion 14 of the bumper 12 may define a contact plane 24. The contact plane 24 may be the forwardmost part of the bumper 12. At the start or onset of an impact event, the object 23 may therefore first contact the bumper 12 in the contact plane 24. The contact plane 24 is shown in the Figures by a dashed line. As shown in the embodiment in the Figures, the contact plane 24 may be substantially perpendicular to the ground when the bumper assembly 10 is attached to the vehicle 1000. The contact plane 24 may be substantially perpendicular to the forward direction of motion of the vehicle 1000. In the embodiment shown in the Figures, the first support surface 22 is substantially planar and vertical. As such, substantially the whole of the first support surface 22 provides the contact plane 24. However, in alternative embodiments, the first support surface 22 may not be planar. In such embodiments, the contact plane 24 may be defined by a forwardmost part of the first support surface 22. The first support surface 22 of the upper portion 14 of the bumper 12 may be configured to deform during an impact event. Therefore, when the object 23 contacts the first support surface 22, the object 23 causes the first support surface 22 to deform. The first support surface 22 may absorb some of the force of the impact event. The upper portion 14 of the bumper 12 may comprise one or more spaces or cavities (not shown) behind the first support surface 22 of the upper portion 14 of the bumper 12 to accommodate deformation of the first support surface 22. The upper portion 14 of the bumper 12 may comprise a deformable or flexible material from which the first support surface 22 is formed. For example, the panels 18 and grilles 20 of the upper portion 14 of the bumper 12 may be formed from a deformable or flexible material. The bumper assembly 10 may comprise a sensor 26 for detecting deformation of the first support surface 22. The sensor 26 may be configured to output a deformation signal in response to detecting deformation of the first support surface 22. The sensor 26 may be positioned behind the first support surface 22. The sensor 26 may be positioned from 1 cm to 3 cm behind the first support surface 22. The sensor 26 may be positioned behind the one of the panels 18 or the grilles 20 of the upper portion 14 of the bumper 12. The sensor 26 may be positioned behind the part of the first support surface 22 that defines the contact plane 24. The sensor 26 may be a pressure sensor 26. During an impact event, the first support surface 22 deforms placing a pressure on the sensor 26 which is behind the first support surface 22 so that the deformation is detected. In certain embodiments, the sensor 26 may comprise at least two sensors 26 spaced apart across the first support surface 22 to improve detection of deformation across the upper portion 14 of the bumper 12. For example, a sensor 26 may be position towards each lateral side of the first support surface 22. In certain embodiments, the sensor 26 extend substantially across the width of the first support surface 22. The sensor or sensors 26 may be positioned at or near the top of the first support surface 22 such that deformation caused by objects 23 of a certain height are detected. As described above, the object 23 may, for example, be a lower limb of a pedestrian. The sensor 7 may be positioned at a particular height above the ground to improve detection of an impact event where the object is a lower limb of a pedestrian. The position of the sensor 26 may be chosen to reduce the detection of impact events with other types of objects that are, for example, smaller or closer to the ground. For example, the sensor 26 may be positioned at least 880 mm above the ground when the bumper assembly 10 is attached to the vehicle 1000. The sensor 26 may be positioned no more than 970 mm above the ground when the bumper assembly 10 is attached to the vehicle 1000. As such, the sensor 26 may be positioned from 880 to 970 mm above the ground when the bumper assembly 10 is attached to the vehicle 1000. The lower portion 16 of the bumper 12 comprises an outer surface 28. The lower portion 16 of the bumper 12 may comprise a tow-eye 13 attached thereto as shown in Figure 1. As shown in the embodiment in the Figures, the lower portion 16 of the bumper 12 may extend from or adjoins the upper portion 14 of the bumper 12. However, in alternative embodiments, the bumper 12 may comprise a central portion extending between the upper and lower portions 14, 16 of the bumper 12. The lower portion 16 of the bumper 12 may comprise a panel. The lower portion 16 of the bumper 12 may have a smaller lateral extent than the upper portion 14 of the bumper 12. The lower portion 16 of the bumper 12 may be aligned with the first support surface 22 of the upper portion 14 of the bumper 12. The lateral extent of the lower portion 16 of the bumper 12 may be at least the same as the lateral extent of the first support surface 22 of the upper portion 14 of the bumper 12. As shown in the non-limiting embodiment in the Figures, the lower portion 16 of the bumper 12 may extend laterally from a position aligned with one of the headlights 1006 of the vehicle 1000 to a position aligned with the other headlight 1006 of the vehicle 1000. The outer surface 28 of the lower portion 16 of the bumper 12 is inclined relative to the first support surface 22 of the upper portion 14 of the bumper 12. Providing the lower portion 16 of the bumper 12 with an inclined outer surface 28 may increase the approach angle of the vehicle 1000. The outer surface 28 of the lower portion 16 of the bumper 12 may extend in a rearwards direction (i.e. towards a rear of the vehicle 1000 when the bumper assembly 10 is attached to the vehicle 1000) relative to the first support surface 22. The outer surface 28 of the lower portion 16 of the bumper 12 is therefore below and extends rearwards of the first support surface 22 of the upper portion 14 of the bumper 12. The outer surface 28 of the lower portion 16 of the bumper 16 may extend from a front edge 30 to a rear edge 32. As shown in the embodiment in the Figures, the outer surface 28 of the lower portion 16 of the bumper 12 may extend from the first support surface 22 of the upper portion 14 of the bumper 12 in the rearwards direction. Thus, the front edge 30 of the outer surface 28 may be adjacent to the first support surface 22 of the upper portion 14 of the bumper 12. As shown in the embodiment in the Figures, the first support surface 22 may be substantially vertical. The outer surface 28 of the lower portion 16 of the bumper 12 is inclined relative to the vertical. An angle a from the first support surface 22 of the upper portion 14 of the bumper 12 to the outer surface 28 may be from 210 degrees to 240 degrees. The angle a may correspond to an approach angle of the vehicle 1000. The bumper assembly 10 comprises an air bag 34 for deployment during an impact event with the object 23. The air bag 34 is deployable from a position on the bumper 12 that is below and rearwards of the first support surface 22 of the upper portion 14 of the bumper 12. The air bag 34 may be deployable from a central position on the bumper 12. As shown in the embodiment in the Figures, the lower bumper 12 may comprise the air bag 34. The air bag 34 may deployable from the outer surface 28 of lower portion 16 of the bumper 12. However, in an alternative embodiment, the air bag 34 may be deployable from a portion of the bumper 12 that is between the upper and lower portions 14,16 (i.e. a central portion). As shown in the Figures, the lower portion 16 of the bumper 12 may comprise a recess 36 in the outer surface 28. The recess 36 may be positioned centrally in the outer surface 28 of the lower portion 16 of the bumper 12. The air bag 34 may be stowed in the recess 36 as shown in Figure 1. The air bag 34 may be folded when stowed. The tow-eye 13 may also be positioned in the recess 36. The air bag 34 may be positioned above the tow-eye 13. The bumper assembly 10 may comprise a detachable cover 38, shown in Figure 8, arranged to cover 38 the recess 36 and air bag 34. The cover 38 may be removably attached to the outer surface 28 of the bumper 12 by one or more fasteners. The fasteners may be received in apertures 40 in the outer surface 28 of the lower portion 16 of the bumper 12. The cover 38 is configured to detach from the lower portion 16 of the bumper 12 when the air bag 34 inflates. During inflation, the air bag 34 exerts a force on the cover 38 to cause the cover 38 to detach from the bumper 12. Figure 2 shows an air bag assembly 42. The bumper assembly 10 may comprise the air bag assembly 42. The air bag assembly 42 comprises the air bag 34. The air bag 34 is shown in a stowed configuration in Figure 2. The air bag assembly 42 may be attached to the lower portion 16 of the bumper 12 by one or more fasteners 44. The air bag assembly 42 may be attached to the lower portion 16 of the bumper 12 such that the air bag assembly 42 is configured to deploy the air bag 34 in a direction substantially perpendicular to the outer surface 28 of the lower portion 16 of the bumper 12. For example, the air bag assembly 42 may be orientated relative to the outer surface 28 of the lower portion 16 of the bumper 12 such that the direction of deployment is direction substantially perpendicular to the outer surface 28 of the lower portion 16 of the bumper 12. The air bag assembly 42 may comprise a gas generator 44 for inflating the air bag 34. The gas generator 44 may be, for example, a pyrotechnic charge or a compressed gas stored in a pressure vessel. The gas generated may be connected to the air bag 34 via a gas passageway (not shown). The air bag assembly 42 may comprise an initiation mechanism 46 to deploy the air bag 34. The initiation mechanism 46 may be configured to cause the gas generator 44 to release gas to inflate (i.e. deploy) the air bag 34. The air bag assembly 42 may comprise a control system 48 configured to activate the initiation mechanism 46. The control system 48 may be configured to deploy the air bag 34 in a direction substantially perpendicular to the outer surface 28 of the lower portion 16 of the bumper 12. The air bag 34 is for deployment during an impact event. Figures 1, 3, 4A and 4B show the air bag 34 prior to deployment. Figures 5A and 5B show the air bag 34 partway through deployment. Figures 6A and 6B show the air bag 34 when the air bag 34 is fully inflated. An outer surface of the air bag 34 provides a second support surface 50 for contacting an object 23 upon deployment. The second support surface 50 of the air bag 34 provides support for the object 23 during an impact event below the first support surface 22 of the upper portion 14 of the bumper 12. The air bag 34 therefore increases the support provided to the object 23 during an impact event. Upon deployment, the air bag 34 is configured to be compressed between the object 23 and the outer surface 28 of the lower portion 16 of the bumper 12 such that the air bag 34 supports the object 23 as it rotates beneath the bumper assembly 10 during an impact event. The air bag 34 may be configured to cover 38 the outer surface 28 of the lower portion 16 of the bumper 12 when fully deployed. Figures 6A and 6B show the deployed the air bag 34 and the object 23. In Figures 6A and 6B, the object 23 has rotated beneath the bumper assembly 10 and the air bag 34 is compressed between the object 23 and the inclined outer surface 28 of the lower portion 16 of the bumper 12. The outer surface 28 of the lower part 16 of the bumper 12 provides an inclined reaction surface for the air bag 34 so that the air bag 34 supports the object 23 as it rotates beneath the bumper assembly 10 during an impact event. A lowermost part of the air bag 34 is spaced apart from (i.e. above) the ground throughout deployment. The air bag 34 therefore does not prevent the object 23 from rotating or moving beneath the bumper assembly 10 during an impact event. However, the air bag 34 limits the amount by which the object 23 rotates beneath the bumper assembly 10 and supports the object 23 as it rotates. As shown in Figures 6A and 6B, a portion 52 of the second support surface 50 of the air bag 34 is rearward of the first support surface 22 and spaced apart from the ground. This portion 52 of the second support surface 50 of the air bag 34 provides the support to the object 23 as the object 23 rotates beneath the bumper assembly 10 during an impact event. Upon deployment, the air bag 34 effectively reduces the distance between the bumper 12 and the ground by increasing the vertical extent of the bumper 12. When deployed, the air bag 34 may extend below the lowermost part of the outer surface 28 of the lower portion 16 of the bumper 12. However, as mentioned above, the lowermost part of the air bag 34 is spaced apart from the ground when deployed. The air bag 34 may be configured to increase the vertical extent of the bumper 12 in the contact plane by up from 200 mm to 300 mm. The air bag may be configured to extend from 100 mm to 160 mm below the lowermost part of the lower bumper 16 upon deployment. The lowermost part of the air bag 34 may be spaced apart from the ground when deployed by a distance from 170 mm to 200 mm. As described above, the first support surface 22 of the upper portion 14 of the bumper 12 defines a contact plane 24. Upon deployment, a portion 54 of the second support surface 50 of the air bag 34 may reside substantially in the contact plane 24 to provide an extension to the first support surface 22 in the contact plane 24. This is shown in Figures 5A to 6B where a portion 54 of the surface of the air bag 34 is in line with the contact plane 24. In addition to supporting the object 23 as it rotates beneath the bumper assembly 10, the air bag 34 may therefore increase the vertical extent of the support provided by the first support surface 22 of the upper portion 14 of the bumper 12. The air bag 34 may be configured such that upon deployment the air bag 34 does not extend beyond the contact plane 24 in a forwards direction. That is, the maximum extent of the air bag in the forwards direction may be limited such that the air bag 34 does not cross the contact plane. The bumper assembly 10 may comprise a controller for controlling deployment of the air bag 34. An embodiment of the controller 56 is illustrated in Figure 7, although it will be appreciated that this is merely illustrative. The controller 56 comprises processing means and memory means. The processing means may be one or more electronic processors 58 which operably executes computer-readable instructions. The memory means 60 may be one or more memory devices. The memory means 60 is electrically coupled to the processing means. The memory means 60 is configured to store instructions, and the processing means is configured to access the memory means 60 and execute the instructions stored thereon. The controller 56 comprises an input means 62 and an output means 64. The input means 62 may comprise an electrical input of the controller 56. The output means 64 may comprise an electrical output of the controller 56. The controller 56 may be configured to cause deployment of the air bag 34 during an impact event. As described above, the sensor 26 may output a deformation signal 66 in response to detecting deformation of the first support surface 22 during an impact event. The one or more processors 58 of the controller 58 may be collectively configured to receive the deformation signal 66 from the sensor 26. The input 62 may be arranged to receive the deformation signal 66 from the sensor 26. The deformation signal 66 is an electrical signal indicative of deformation of the first support surface 22 of the bumper 12 due to an impact event with an object 23. The one or more processors 58 of the controller 56 may be collectively configured to determine the existence of an impact event with an object 23 based on the deformation signal 66. That is, the controller 56 may be configured to determine whether an impact event is currently occurring based on receipt of the deformation signal 66 which indicates that an object 23 has contacted the first support surface and 22 caused deformation to the first support surface 22. The one or more processors 58 of the controller 56 may be collectively configured to output a deployment signal 68 to the air bag assembly 42 to deploy the air bag 34. The controller 56 may be configured to output the deployment signal 68 to the air bag assembly 42 in response to determining that an impact event exists. The output 64 of the controller 56 may be arranged to output the deployment signal 68 to the air bag assembly 42. The control system 48 of the air bag assembly 42 may be configured to receive the deployment signal 68. The control system 48 of the air bag assembly 42 may be configured to activate the initiation mechanism 46 to cause the gas generator 44 to release gas to inflate (i.e. deploy) the air bag 34. The air bag 34 is therefore deployed after the object 23 has made contact with the bumper 12. The air bag 34 is not preemptively deployed. Deploying the air bag after the object 23 has made contact with the bumper 12 may ensure that the air bag 34 is only deployed during an impact event and reduces the risk of the air bag 34 being deployed when is it not needed. Deploying the air bag after the object 23 has made contact with the bumper 12 may improve the support the air bag 34 provides for the object 23 as it rotates beneath the bumper assembly 10 due to the sequence with which the object 23 interacts with the parts of the bumper assembly 10. The controller 56 may be configured to control deployment of the air bag 34 in dependence on a ride height of the vehicle 1000. The bumper assembly 10 may be used on a vehicle 1000 having multiple ride heights. The vehicle 1000 may have first and second ride heights, the second ride height may be higher than the first ride height. As such, when the vehicle 1000 is in the second ride height the ground clearance and approach angle of the vehicle 1000 may be greater than when the vehicle is in the first ride height. The second ride height may be the highest ride height of the vehicle 1000. The second ride height may be an off-road ride height. When the vehicle 1000 is in the second (i.e. higher) ride height, the air bag 34 may provide beneficial support below the first support surface 22 of the upper portion 14 of the bumper 12 to the object 23 during an impact event. The air bag 34 may at least partially fill a space below the bumper 12 that is created when the ride height is increased from the first to the second ride height. When deployed, the air bag 34 reduces the approach angle of the vehicle and may reduce the ground clearance of the vehicle. When the vehicle 1000 is in the first (i.e. lower) ride height, the first support surface 22 of the upper portion 14 of the bumper 12 and the outer surface 28 of the lower portion 16 of the bumper 12 may provide sufficient support for the object 23 during an impact event. The additional support provided by the air bag 34 to an object 23 during an impact event may therefore not be needed and may provide no additional benefit when vehicle 1000 is in the first (i.e. lower) ride height. The controller 56 may be configured to control deployment of the air bag 34 in dependence on a ride height that the vehicle 1000 to prevent unnecessary deployment of the air bag 34. The one or more processors 58 of the controller 56 may be selectively configured to receive a ride height signal 70 indicative of a current ride height. The current ride height may be either the first ride height or the second ride height. The input 62 may be arranged to receive the ride height signal 70. The ride height signal 70 is an electrical signal indicative of the current ride height that the vehicle 1000 is in. The input 62 of the controller 56 may be configured to receive the ride height signal 70 from, for example, a main vehicle control system (not shown) of the vehicle 1000 or, for example, the suspension system (not shown) of the vehicle 1000 which may control the ride height of the vehicle 1000. The one or more processors 58 of the controller 56 may be selectively configured to control deployment of the air bag 34 in dependence on the ride height signal 70 such that the air bag 34 is deployable if the current ride height is the second ride height and deployment of the air bag 34 is prevented if the current ride height is the first ride height. The controller 56 may be configured to allow output of the deployment signal 68 during an impact event if the current ride height is the second ride height. The controller 56 may be configured to prevent output of the deployment signal 68 during an impact event if the current ride height is the second ride height. The controller 56 ensures that the air bag 34 is not deployed when the vehicle 1000 is in the first ride height. It follows that, when an impact event between the object 23 and the first support surface 22 of the bumper assembly 12 occurs, the one or more processors 58 of the controller 56 may be configured to receive the deformation signal 66 indicative that deformation of the first support surface 22 of the bumper 12 has occurred due to an impact event with then object 23. The one or more processors 58 of the controller 56 may be configured to determine the existence of an impact event based on the deformation signal 66 and 11 determine the current ride height based on the ride height signal 70. The controller 56 may be configured to receive the ride height signal 70 indicative of a current ride height either before or during the impact event. The one or more processors 58 the controller 56 may be configured to output the deployment signal 68 to the air bag assembly 42 to deploy the air bag 34 in response to determining that an impact event exists and the current ride height is the second ride height. The one or more processors of the controller 56 may be configured to prevent output of the deployment signal 68 is if the current ride height is the first ride height. In an embodiment, the one or more processors 58 of the controller 56 may be further collectively configured to determine if the current ride height is the second ride height and the current vehicle speed exceeds an upper speed threshold. The upper speed threshold may be from 35 km / h up to 55 km / h, for example, the upper speed threshold may be 55 km / h. If the upper speed threshold is exceeded and the vehicle 1000 is in the second ride height, the controller 56 may be configured to cause the vehicle 1000 ride height to transition from the second ride height to the first ride height. In particular, the one or more processors 58 of the controller 56 may be collectively configured to, in response to determining that the current ride height is the second ride height and the current vehicle 1000 speed exceeds the upper speed threshold, output a transition signal 74 to transition from the second ride height to the first ride height and prevent deployment of the air bag 34 once the vehicle 1000 is in the first ride height. The controller 56 may be configured to prevent output of the deployment signal 68 during an impact event once the vehicle 1000 is in the first ride height. The output of the controller 56 may be arranged to output the transition signal 74. The transition signal 74 may be sent to the vehicle 1000 suspension system or a main vehicle 1000 control system. The controller 56 may be configured to control deployment of the air bag 34 in dependence on a vehicle 1000 speed. If the vehicle speed is low, the first support surface 22 of the upper portion 14 of the bumper 12 and the outer surface 28 of the lower portion 16 of the bumper 12 may provide sufficient support for the object 23 during an impact event. The additional support provided by the air bag 34 to an object 23 during an impact event may therefore not be needed. The one or more processors 58 of the controller 56 may be configured to receive a vehicle speed signal 72 indicative of a current vehicle 1000 speed. The input 60 may be arranged to receive the vehicle speed signal 72. The vehicle speed signal 72 is an electrical signal indicative of the current speed height at which the vehicle 1000 is travelling. The input 60 of the controller 56 maybe configured to receive the vehicle speed signal 72 from, for example, a main control system of the vehicle 1000. The one or more processors 58 of the controller 56 may be configured to control deployment of the air bag 34 in dependence on the vehicle speed signal 72 such that: the air bag 34 is deployable if the current vehicle speed is at or above a lower vehicle speed threshold; and deployment of the air bag 34 is prevented if the current vehicle speed is below the lower vehicle speed threshold. The controller 56 may be configured to allow output of the deployment signal 68 during an impact event if the current vehicle speed is at or above the lower vehicle speed threshold. The controller 56 may be configured to prevent output of the deployment signal 68 during an impact event if the current vehicle speed is below the lower vehicle speed threshold. Therefore, the controller 56 ensures that the air bag 34 is not deployed when the vehicle 1000 is travelling at low speeds where the additional support provided by the air bag 34 during an impact event may not be beneficial. As such, unnecessary deployment of the airbag 34 maybe prevented. The lower vehicle 1000 speed threshold may be in the range of 3 km / h to 8 km / h. In certain embodiments, the lower vehicle 1000 speed threshold may be 5 km / h. It follows that, when an impact event between the object 23 and the first support surface 22 of the bumper assembly 12 occurs, the one or more processors of the controller 56 may be configured to receive the deformation signal 66 indicative that deformation of the first support surface 22 of the bumper 12 has occurred due to an impact event with then object 23 and to receive a vehicle speed signal 72 indicative of a current vehicle 1000 speed. The vehicle speed signal 72 may be received by the controller 56 after the controller 56 has received the deformation signal 66. The one or more processors 58 of the controller 56 may be configured to determine the existence of an impact event based on the detection signal and determine the current vehicle speed based on the vehicle speed signal 72. The one or more processors 58 of the controller 56 may be configured to output the deployment signal 68 to the air bag assembly 42 to deploy the air bag 34 in response to determining that an impact event exists and the current vehicle speed is at or above the lower vehicle speed threshold. The one or more processors of the controller 56 may be configured to prevent output of the deployment signal 68 is if the current vehicle speed is below the lower vehicle speed threshold. The controller 56 may be configured to control deployment of the air bag 34 in dependence on both the ride height of the vehicle 1000 and the vehicle 1000 speed. Therefore, the one or more processors 58 of the controller 56 may be configured to control deployment of the air bag 34 in dependence on the ride height signal 70 and the vehicle speed signal 72 such that: the air bag 34 is deployable if the current ride height is the second ride height and the current vehicle 1000 speed is at or above a lower vehicle 1000 speed threshold; and deployment of the air bag 34 is prevented if the current ride height is the first ride height or the current vehicle 1000 speed is below the lower vehicle 1000 speed threshold. The one or more processors 58 of the controller 56 may be configured to output the deployment signal 68 to the air bag assembly 42 to deploy the air bag 34 in response to determining that an impact event exists, the current vehicle speed is at or above the lower vehicle speed threshold and the current ride height is the second ride height. The one or more processors of the controller 56 may be configured to prevent output of the deployment signal 68 in response to determining that either the current vehicle speed is below the lower vehicle speed threshold or the current ride height is the first ride height. Therefore, the controller 56 ensures that the air bag 34 is not deployed when the vehicle 1000 is travelling either at low speeds or when the vehicle 1000 is in the first ride height where the additional support provided by the air bag 34 during an impact event may not be beneficial. In the above-described embodiment, first and second ride heights are discussed. One or both the first and second ride heights may comprise multiple ride heights. For example, the first ride height may comprise a plurality of ride heights. The plurality of ride heights may comprise a first off-road ride height and an on-road ride height, the first off-road ride height being higher than the on-road ride height. The plurality of ride heights may comprise an accessible ride height to improve access to the vehicle 1000 for a passenger or driver. The on-road ride height is higher than the accessible ride height. As such, the controller 56 is configured to prevent deployment of the air bag 34 when the vehicle 1000 is in any of the first off-road ride height, the road ride height or the accessible ride height. The controller 56 prevents deployment of the air bag 34. The second ride height may comprise a second off-road ride height which is higher than the first off-road ride height. Figures 3 to 6B show the bumper assembly 10 during use on a vehicle 1000 in an impact event. Figure 3 shows the bumper assembly 10 and object 23 just prior to an impact event. Figures 4A to 6B show the bumper assembly 10 and object 23 during an impact event. At the start of an impact event, the object 23 contacts the first support surface 22 of the bumper 10 in the collision plane 24. This contact causes the first support surface 22 to deform as shown in Figures 4A and 4B. The deformation of the first support surface 22 is detected by the sensor 26 and the deployment signal is sent to the controller 56. If the vehicle 1000 is in the second ride height and travelling at or above the lower speed threshold, the controller 56 may output the deployment signal 68 to the control system 48 of the air bag assembly 42 to deploy the air bag 34. In response to the receipt of the deployment signal 68, the control system 48 of the air bag assembly 42 may activate the initiation mechanism 46 to cause the air bag 34 to inflate. Deploying the air bag 34 once deformation of the bumper 12 has occurred (i.e. after the onset of an impact event) may ensure that the air bag 34 is only deployed during an impact event and may prevent air bag 34 being deploying when is it not needed, such as during very low speed impact events, for example whilst parking the vehicle 1000, or during off-road driving on uneven surfaces such as through sand dunes. Deploying the air bag after the object 23 has made contact with the bumper 12 may improve the support the air 13 bag 34 provides for the object 23 as it rotates beneath the bumper assembly 10 due to the sequence with which the object 23 interacts with the parts of the bumper assembly 10. Deploying the air bag 34 when the vehicle 1000 is in the higher second ride height and not when the vehicle 1000 is in the lower, first ride height may prevent air bag 34 being deploying when it is not needed. When the vehicle 1000 is in the lower ride height, the first support surface 22 of the upper portion 14 of the bumper 12 and the outer surface 28 of the lower portion 16 of the bumper 12 provide sufficient support for the object 23 during an impact event. As such, the air bag 34 does not need to be deployed when the vehicle 1000 is in the first ride height. When the vehicle 1000 is in the second ride height, the air bag 34 may be deployed during an impact event to effectively fill a space below the bumper 12 that was created when raising the vehicle 1000 in height from the first to the second ride height. The second ride height may be greater than the first ride height by a range of 30 to 80 mm. As the air bag 34 inflates, as shown in Figures 5A to 6B, the air bag 34 causes the cover 38 to detach from the bumper 12. The air bag 34 is then compressed between the object 23 and the outer surface 28 of the lower portion of the bumper 12. Figures 5A and 5B show the air bag 34 partway through deployment. At this stage of the impact event, the object 23 has not yet rotated beneath the bumper assembly. As shown in the Figures, the object may be substantially vertical. As the air bag 34 inflates, it provides a second support surface 50 for the object 23. As shown in Figure 5A, a portion 54 of the second support surface 50 of the air bag 34 may be in the contact plane 24 to provide an extension to the first support surface 22 in the contact plane 24. Figures 6A and 6B show the air bag 34 when the air bag 34 is fully inflated. At this stage of the impact event, the object 23 has rotated partway beneath the bumper assembly as the lower portion of the object 23 not yet contacted the vehicle 1000 or air bag 34. As shown in Figures 6A and 6B, the air bag 34 supports the object 23 as it rotates beneath the bumper assembly 10. The portion 52 of the second support surface 50 of the air bag 34 that is rearward of the first support surface 22 and spaced apart from the ground supports the object 23 as it rotates beneath the bumper assembly 10. The amount of rotation of the lower portion of the object 23 beneath the bumper assembly 10 may also be limited by the support provided by the air bag 34 as the air bag 34 effectively reduces the distance between the bumper 12 and the ground. As described above, the object 23 may, for example, be a lower limb of a pedestrian. Reducing the amount of rotation beneath the bumper assembly 10 and providing support is particularly advantageously when the object 23 is a lower limb of a pedestrian. As shown in Figures 6A and 6B, the portion 54 of the second support surface 50 of the air bag 34 may still be in the contact plane 24 when the air bag 34 is fully inflated providing an extension to the first support surface 22 in the contact plane 24. The extension to the first support surface 22 in the contact plane 24 by the air bag 34 is shown in Figures 5A to 6B and provided through the impact event. The extension increases the support provided by the bumper assembly 10 in the contact plan 24 during an impact event and may reduce also the amount by which the object 23 rotates beneath the vehicle. Increasing the support provided in the contact plane 25 and reducing the amount by which the object 25 rotates beneath the vehicle 12 is particularly advanteagous when the object 26 is a lower limb of a pedestrian. The skilled person will appreciate that various modifications can be made to the above-described embodiment without departing from the scope of the invention. In the above-described embodiment, the bumper assembly 10 comprises one air bag 34. However, in alternative embodiments, the bumper assembly may comprise a plurality of air bags collectively configured to provide the second support surface during the impact event. The plurality of air bags may be distributed across the outer surface of the lower portion of the bumper. The controller may be configured to deploy all of the plurality of air bags during an impact event. In the above-described embodiment, the sensor 26 is configured to detect deformation of the first support surface 22 of the bumper assembly 10. However, in alternative embodiments a different sensor may be used. The sensor may be configured to detect an impact event between the bumper and an object. For example, the sensor may be configured to detect rapid deceleration of the vehicle or utilise lidar or radar to detect an object. The sensor may be configured to output a detection signal in response to detection of an 5 impact event. The one or more processors of the controller may be collectively configured to receive the detection signal from the sensor and determine the existence of an impact event based on the detection signal. The one or more processors of the controller may be collectively configured to, in response to determining the existence of an impact event, output a deployment signal to the air bag assembly to deploy. The detection signal may be used in place of the deformation signal 68 of the above-described embodiment.

Claims

1. A bumper assembly for a vehicle, the bumper assembly comprising: a bumper comprising an upper portion and a lower portion; and an airbag for deployment during an impact event with an object; wherein the upper portion comprises a support surface for contacting an object during an impact event; wherein the lower portion of the bumper comprises an outer surface that is inclined relative to the support surface; and wherein, upon deployment, the airbag is configured to be compressed between an object and the outer surface of the lower portion of the bumper such that the airbag is configured to support an object as the object rotates beneath the bumper assembly during an impact event.

2. A bumper assembly according to claim 1, wherein, upon deployment, a portion of the surface of the air bag is rearward of the support surface and spaced apart from the ground to support an object as the object rotates beneath the bumper assembly during an impact event.

3. A bumper assembly according to any one of the preceding claims, wherein the air bag is deployable from a position on the bumper that is below and rearwards of the support surface of the upper portion of the bumper.

4. A bumper assembly according to any one of the preceding claims, wherein the lower bumper comprises the air bag and the air bag is deployable from the outer surface of the lower portion of the bumper.

5. A bumper assembly according to claim 4, wherein the lower portion of the bumper comprises a recess in the outer surface and the air bag is stowed in the recess.

6. A bumper assembly according to claim 5, comprising a detachable cover arranged to cover the recess.

7. A bumper assembly according to any one of the preceding claims, comprising an air bag assembly, wherein the air bagassembly comprises the air bag, the air bag assembly being arranged to deploy the air bag in a direction substantially perpendicular to the outer surface of the lower portion of the bumper.

8. A bumper assembly according to any one of the preceding claims, wherein the air bag is configured to cover the outer surface of the lower portion of the bumper upon deployment.

9. A bumper assembly according to claim 8, wherein the outer surface of the lower portion of the bumper extends from the support surface of the upper portion of the bumper in a rearwards direction.

10. A bumper assembly according to any one of the preceding claims, wherein the outer surface of the lower portion of the bumper is inclined relative to the support surface of the upper portion of the bumper such that an angle from the support surface to the outer surface is in a range from 210 degrees to 240 degrees.

11. A bumper assembly according to any one of the preceding claims, wherein the support surface of the upper portion of the bumper defines a contact plane and, upon deployment, a portion of a surface of the air bag resides substantially in the contact plane to provide an extension to the support surface in the contact plane.

12. A bumper assembly according to claim 11, wherein the air bag is configured such that upon deployment the air bag does not extend beyond the contact plane in a forwards direction.

13. A bumper assembly according to claim 11 or 12, wherein the contact plane is substantially perpendicular to the ground when the bumper assembly is attached to a vehicle14. A bumper assembly according to any one of the preceding claims, wherein, upon deployment the air bag is configured to reduce the height of the bumper above the ground by up to 190 mm or up to 170 mm.5 15. A vehicle comprising the bumper assembly according to any one of the preceding claims.

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