GB2499033A

GB2499033A - Active hood or bonnet system for a vehicle

Info

Publication number: GB2499033A
Application number: GB1201966.7A
Authority: GB
Inventors: Bill Mclundie
Original assignee: Jaguar Cars Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2012-02-06
Filing date: 2012-02-06
Publication date: 2013-08-07
Anticipated expiration: 2032-02-06
Also published as: GB2499033B; GB201201966D0

Abstract

A vehicle (10) comprising a bonnet or hood (12) having a passive pedestrian impact section (P) and a second active pedestrian impact section (A); the first and second sections being coupled together by a hinge (32); the second active section being deployable by an actuator (30) upon receipt of a deploy signal from a control unit (39). The control unit receives data input from sensors (22) or other measurement devices and determines if the predetermined conditions for deployment of the second active section are met.

Description

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Active Hood or Bonnet System for a Vehicle

Technical Field

The present invention relates to an active hood or bonnet system for a vehicle and particularly, 5 but not exclusively, to a dual zone hood or bonnet system that is intended to manage the energy from an impact between a pedestrian and the bonnet or hood region of a vehicle during a pedestrian/vehicle collision using both passive and active safety measures. Aspects of the invention relate to a vehicle bonnet assembly, a vehicle, a control unit and to a method.

10 Background

In the event of a collision between a pedestrian and a vehicle, serious injury can occur depending upon the speed and trajectory of the pedestrian relative to the vehicle during the event.

15 The kinematics of a pedestrian during a collision with a moving vehicle can be complex but can be considered in four stages. In the first stage, the leading edge of the vehicle, usually the bumper, initially contacts the leg of a pedestrian. In a second stage, a leading edge of the bonnet or hood contacts the upper leg of the pedestrian. In the third stage, the pedestrian tends to fall over towards the vehicle, wrapping around or rolling over onto an upper surface of the 20 bonnet or hood. The pedestrian's upper body and/or head may contact the bonnet directly. Depending upon the size and stature of the pedestrian, the speed of the collision, and the vehicle size and shape, the pedestrian may make contact with the windscreen or surrounding structure. In the fourth stage, the pedestrian lands on the bonnet, deforming it as the bonnet supports their mass during the event. This deformation serves to absorb at least some of the 25 energy from the impact.

The bonnet is arranged to cover components such as the engine, battery and vehicle suspension components. By necessity, these components are substantially rigid and so it is desirable to prevent direct contact between a pedestrian and such components in the event of 30 an impact. Deformation of the bonnet towards these components is managed, so as to provide maximum deformation space for the bonnet, thus absorbing as much of the energy from the impact as possible.

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In order to increase the available space for bonnet deformation, it is known to provide a vehicle with an active bonnet, such systems comprise one or more sensors for detecting contact with a pedestrian. Active bonnets are intended to deploy to an elevated position in the event of an impact with a pedestrian, increasing the available space into which the bonnet may deform and 5 thus increase the amount of energy that may be absorbed by the bonnet from such an event. Typically, active bonnet systems are arranged to raise an entire, unitary upper surface of the bonnet away from the engine and other structures in the engine bay during deployment.

The time elapsed between the initial impact with a pedestrian, and their upper body or head 10 contacting the bonnet depends upon a number of factors, including the vehicle shape or profile. The leading edge of the bonnet typically presents a pivot or bending point about which a pedestrian tends to wrap around in the event of a collision. The time between the pedestrian first contacting the leading edge of the bonnet and their upper body contacting the top of the bonnet is dependent in part on the height of the pedestrian, generally a shorter height results in 15 a shorter interval.

It is desirable that the active bonnet is deployed to an elevated position and in a static condition before it is called upon to support the mass of a pedestrian during an impact.

20 In some circumstances, it may be difficult to fully deploy the entire bonnet to a static condition before the pedestrian makes contact with it, due to the inertia of the active bonnet and the time needed to raise it to a fully deployed position.

It is against this background that the present invention has been conceived. Embodiments of the 25 invention may provide a bonnet assembly, a system, a vehicle or a method that overcomes or at least mitigates the problems of the prior art. Other aims and advantages of the invention will become apparent from the following description, claims and drawings.

Summary

30 Aspects of the invention relate to a vehicle bonnet assembly, a vehicle, a control unit and to a method as claimed in the appended claims.

According to another aspect of the invention for which protection is sought, there is provided a vehicle bonnet assembly for managing the energy from an impact with a pedestrian, the

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assembly comprising at least one passive pedestrian impact protection section and at least one active pedestrian impact protection section wherein both passive and active pedestrian impact protection section are provided on an upper surface of the bonnet assembly and the active pedestrian impact protection section is arranged to be moveable relative to the passive 5 pedestrian impact protection section

The active section may be moveable from a non-deployed position to a deployed position, wherein, in the deployed position, at least a portion of the active section is arranged, when the bonnet assembly is in use on a vehicle, to provide an increased space for displacement or

10 deformation between active section and items, such as, but not limited to; vehicle components including for example; engine, engine mounts, suspension turrets; spare wheel; luggage; or other cargo, disposed beneath the active section than when said portion is in the non-deployed position.

15 Advantageously, the active section of the bonnet may be arranged to be sufficiently rigid to support the pedestrian during an impact and spread the load over as wide an area of the vehicle as possible. In this way, the active section of the bonnet manages the energy of the impact with the pedestrian by a combination of deflection towards the vehicle, and controlled localised deformation.

20

In one embodiment the bonnet assembly is arranged such that, on deployment of the active section, movement of the active section is constrained. The bonnet assembly may be arranged such that, when the active region is deployed, the bonnet assembly does not obscure the driver's view.

25

Advantageously, the restraining of the active section may control its movement during deployment and manages the final location and attitude of the active section once fully deployed. Ultimately, this control over the deployment kinematics of the active section maintains repeatability and enhances stability under loading by the pedestrian.

30

Optionally, the at least one active section is located rearwards of the passive section.

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In one embodiment the at least one active section comprises an actuator for elevating a moveable portion of the active section and optionally, the moveable portion is pivotally coupled to a static section forming part of the at least one passive section.

5 Optionally, the actuator is an airbag or spring loaded mechanism.

Alternatively, the actuator is pyrotechnically activated or is pneumatically activated.

Optionally, the bonnet assembly is coupled to a control unit for receiving data input from one or 10 more sensors and/or other measurement devices disposed on the vehicle and the control unit being operable to determine, based on predefined criteria, whether to deploy the active section.

Optionally, the bonnet or hood comprises a hinge pivotally coupling the or each at least one passive section to the or each at least one active section. In one embodiment the hinge is a live 15 hinge.

In one embodiment the hinge defines, at least in part, a transition between a passive pedestrian impact section and an active pedestrian impact section.

Optionally, the passive section comprises passive protection measures comprises a passive static or non-deploying energy absorbing region, and the active section comprises a moveable portion moveable between a first, stowed, position and a second, deployed position, wherein deployment of the moveable portion increases the distance between the moveable portion and vehicle components disposed beneath the active section.

In some embodiments the moveable portion extends across the entire bonnet or hood.

Optionally, the active section is disposed towards the rear of the bonnet or hood.

Optionally, the moveable portion is deployed to a stationary position prior to pedestrian impact with the active section. The active section may be provided with an airbag. Optionally, the airbag is the actuator.

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Advantageously, the leading edge of the bonnet may remain static during deployment of the active section. In this way, the leading edge of the bonnet and the passive pedestrian impact protection section may be optimised for energy management independently from active section.

It is envisaged that the bonnet assembly may comprise one or more tethers to limit or restrict movement of the moveable portion. Optionally, the tethers control or otherwise constrict inflation of the airbag across at least a portion thereof.

This has the advantage of maintaining the driver's field of view across at least a portion of the windshield during the deployment of the active section of the bonnet.

It is further envisaged that when in the deployed position, the tethers solely couple the moveable portion to the vehicle, the tethers and the moveable portion may control inflation of the airbag. In this way, the tethers control, and ultimately constrain the maximum displacement of the moveable portion relative to the vehicle during loading.

Optionally, the moveable portion of the bonnet assembly floats or is suspended upon the airbag.

In embodiments where an airbag is provided, inflation of the airbag may be constricted across a central portion thereof, preferably only the central portion of the airbag is constricted.

Optionally, the airbag, when fully inflated, extends beyond the lateral extent of the moveable portion. The airbag may cover the entire width of the bonnet or hood in embodiments of the invention.

Optionally, the moveable portion is disposed over the actuator or airbag and substantially covers at least a central portion of the actuator or airbag when in the deployed position.

Optionally, one or more outer portions of the airbag have a greater maximum elevation than a central region of the airbag and/or than the deployable region in the deployed position.

In some embodiments the active section is effective from a wraparound distance substantially equal to 1700 mm.

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Optionally, the moveable portion is hinged to the vehicle and is pivotally moveable to a deployed position.

It is envisaged that the moveable portion may form a contact and support region which is deformable and/or moveable for absorbing collision energy, the moveable portion being deformable and/or moveable into a space created by deployment of the moveable portion.

According to a further aspect of the invention for which protection is sought, there is provided a vehicle comprising a vehicle bonnet assembly described hereinabove.

According to a still further aspect of the invention for which protection is sought, there is provided a method of deploying an active region of a vehicle bonnet or hood comprising sensing 5 impact with an object, determining that said object may be a pedestrian, activating an actuator to deploy an active region of a vehicle bonnet or hood to an elevated position.

Within the scope of this application it is envisaged that the various aspects, embodiments, examples and alternatives, and in particular the features thereof, set out in the preceding 10 paragraphs, in the claims and/or in the following description and drawings, may be taken independently or in any combination thereof. For example, features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

Brief description of drawings

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

FIGURE 1 is a side view of a vehicle comprising an active bonnet system according to a first embodiment of the invention;

20

FIGURE 2 is a top view of a vehicle according to Figure 1;

FIGURE 3 is a side view of the vehicle of Figure 1 in which the active bonnet system has been activated or deployed;

25

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FIGURE 4 is a side view of the vehicle of Figure 1 illustrating collision with a small statured pedestrian;

FIGURE 5 is a side view of the vehicle of Figure 1 illustrating collision with a large statured 5 pedestrian;

FIGURE 6 is an enlarged side view of the vehicle of Figure 1;

FIGURE 7 is a cross sectional view through the bonnet or hood of the vehicle illustrated in 10 Figure 1;

FIGURE 8 is a top view of a vehicle according to a second embodiment on the invention;

FIGURE 9A illustrates a cross sectional view of the trailing edge of a bonnet according to an 15 embodiment of the invention in an un-deployed state;

FIGURE 9B corresponds to Figure 9A in which the system is in a deployed state;

FIGURE 10A illustrates a perspective view from above of a leading portion of a vehicle 20 comprising a safety system according to an alternative embodiment of the invention in which the system is in an un-deployed or stowed condition; and

FIGURE 10B corresponds to Figure 10A and shows the system in a deployed condition.

25

Detailed Description

Detailed descriptions of specific embodiments of the active bonnet system are disclosed herein. It will be understood that the disclosed embodiments are merely examples of the way in which certain aspects of the invention can be implemented and do not represent an exhaustive list of 30 all the ways the invention may be embodied. Indeed, it will be understood that the active bonnet system described herein may be embodied in various and alternative forms. The Figures are not necessarily to scale and some features may be exaggerated or minimised to show details of particular components. Well-known components, materials or methods are not necessarily described in great detail in order to avoid obscuring the present disclosure. Any specific

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structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the invention.

5 Referring to Figures 1 and 3, there is shown a side view (Figure 2 shows a top view) of a vehicle 10 which comprises a hood or bonnet assembly 12 having an active pedestrian impact section or active section, region, or zone A and a passive pedestrian impact section or passive section, region, or zone P.

10 The bonnet 12 is disposed in front of a cabin 11 in which the driver may be located. The bonnet 12 defines in part a compartment which may comprise vehicle components such as, but not limited to, an engine 20 and/or suspension components. It is envisaged that in some embodiments, the compartment may be a storage compartment for example for luggage or a spare wheel.

15

The front of the vehicle 10 has a bumper 14 which comprises a leading edge or surface 15. One or more collision sensors 22 are mounted in or behind the bumper 14. In alternative embodiments collision sensors may be located on or in other areas of the vehicle 10 including but not limited to the body panels. The vehicle 10 also comprises a windshield or windscreen 20 16. The windscreen 16 is mounted above a cowl 17 (see Figure 2). Windscreen wipers 18 are provided for clearing precipitation or dirt from the windscreen 16. A wiper motor, linkages and wiper spindles are located beneath or within the cowl 17.

Figure 2 illustrates a plan view of the vehicle 10. The bonnet 12 comprises at least two 25 sections: a first, passive section P, and a second, active section A. The active section A is located behind, that is to say, rearward of the passive section adjacent to the cowl 17.

The passive section P may comprise one or more passive safety devices such as deformable support braces, deformable engine covers, energy absorbing foam and a sacrificial space 30 between bonnet 12 and engine 20 into which the bonnet 12 may deform upon impact. In some embodiments the passive section P may comprise an extended energy absorbing nose cone.

The active section A comprises a moveable portion which is a moveable panel or flap 24 which can be deployed upon sensing impact with a pedestrian S. The flap 24 is raised by an actuator

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30, as illustrated in Figure 6. It is envisaged that one or more actuators 30 may be provided. The actuator 30 may comprise an airbag which is pyrotechnically deployed by a control unit 39 which is coupled thereto, see Figure 7. On deployment, any load applied to the flap 24 is transferred through the whole area of the flap 24 to the actuator 30 such as an airbag 5 underneath. The flap 24 thus spreads the load, and deformation and/or displacement of the flap 24 towards any vehicle components disposed underneath the flap 24 is managed.

The control unit 39 receives data from one or more sensors on the vehicle 10 including the collision sensors 22. When predetermined criteria are met, the control unit 39 sends a deploy 10 signal to the actuator 30 to raise the flap 24 above the height of the surrounding passive section P of the bonnet 12.

In alternative embodiments the flap 24 may be deployed by alternative actuators such as a pre-tensioned spring mechanism which may or may not be pyrotechnically activated; in some 15 embodiments the actuator may be pneumatically deployed.

It is envisaged that the bonnet 12 will be structured so as to bend or hinge about a predetermined location of the bonnet 12. Figure 7 illustrates a schematic representation of a cross-section through the bonnet 12. The bonnet 12 has been constructed so as to have a live 20 hinge 32. When in the undeployed condition, the live hinge 32 is not visible from an external vantage point above the bonnet 12. The sheet material of the bonnet 12 and/or any associated support braces 34, 36 may be reduced in thickness to define a localised weak point relative to the rest of the bonnet 12. Upon activation of the actuator 30, the flap 24 hinges about the live hinge 32. In alternative embodiments the actuator 30 may only displace an outer skin or 25 surface of the bonnet 12, the support braces 34, 36 may not necessarily be displaced, or a conventional hinge mechanism between the two sections may be used.

Figures 3 and 6 illustrate the active bonnet system in a deployed state. The flap 24 has been deployed by activation of the actuator 30. The passive section P is located in front of hinge 32; 30 the active section A is located behind the hinge 32. The active region A of the bonnet 12 has been pivotally moved, as indicated by direction arrow D1 (see Figure 3), about the hinge 32. Typically the flap 24 may be deployed to a height of 80-100 mm above the bonnet surface in the normal undeployed state.

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Figure 4 illustrates schematically the moment of impact between the vehicle 10 and a pedestrian. In the example shown, the stature of the pedestrian is relatively short, as may be representative of an adolescent or short statured adult pedestrian S. The sensors 22 detect the initial impact with the pedestrian S. The control unit 39 determines whether or not to deploy the 5 active region A based upon data received from sensors on the vehicle 10. In some embodiments it is envisaged that the control unit 39 will determine that the vehicle 10 has impacted with a pedestrian. In such circumstances the active region A may remain undeployed. However, in other embodiments, the dashed lines illustrate the condition of the vehicle 10 and pedestrian S at the instant when the upper body of the pedestrian S contacts the vehicle 10. 10 The upper portion of the pedestrian S contacts the passive region P of the bonnet 12 and is supported by passive safety measures, such as static energy absorbing structures or material, forming at least part of the passive region P.

The distance from the ground G to the point of impact of the head of the pedestrian S defines a 15 distance W, hereinafter referred to as the wraparound distance (WAD). The distance W is made up of the distance from the ground to a point of rotation F of the pedestrian about the leading edge of the bonnet, and the distance from that leading edge to the point of contact between the head and the bonnet 12. For any given pedestrian the higher the point F where the pedestrian wraps or rotates about the vehicle 10, the shorter the time interval between the initial 20 contact with the leading edge of the vehicle 10 and the contact between the pedestrian's head or upper body and the bonnet 12. The point of rotation F is typically defined by a characteristic of the vehicle 10, such as the height of the leading edge of the bonnet 12; for any given vehicle design, the time period between the initial impact with the vehicle and an upper body or head contact with the bonnet 12 is directly proportional to the height of the pedestrian.

25

Figure 5 illustrates schematically the moment of impact between the vehicle 10 and an adult or similarly tall statured pedestrian T. The sensors 22 detect the initial impact and the control unit 39 deploys the active region A of the bonnet 12. The flap 24 is raised to a static elevated position prior to any contact between the upper body or head of the pedestrian T with the active 30 region A. The moment in time when the upper body or head of the pedestrian T makes contact with the vehicle 10 is shown in the figures by dashed lines. Thus at least a proportion of the pedestrian T is thus supported by the flap 24 of the active region A. In this way, contact between the pedestrian T and any components which are disposed beneath the bonnet 12 is avoided by virtue of the increased space for deformation below the deployed active region A. In addition,

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direct contact between the pedestrian T and components of the windshield wiper 18 such as the wiper spindles, is also avoided.

Referring now to Figures 8 to 10B, there are shown alternative embodiments of the present 5 invention. In the these embodiments, like numerals have, where possible, been used to denote like parts, albeit with the addition of the prefix "1", "2", or "3" to indicate that these features belong to the alternative embodiments. The alternative embodiments share many common features with the embodiments of Figures 1 to 7 and therefore only the differences from the embodiment illustrated in Figures 1 to 7 will be described in any greater detail.

10

Figure 8 illustrates an above, plan view of a vehicle 110 according to an alternative embodiment. In this embodiment, the door or flap 124, which forms part of the active section of the hood or bonnet 112 may be integrally formed with and defined within, or struck from, the bonnet 112, which is to say it is surrounded by the bonnet 112, and may be stamped out of the 15 bonnet 112, whereas in the first embodiment the flap 24 extends across the entire width of the bonnet 12. In an alternative embodiment, the flap 124 may similarly extend across only a portion of the width of the bonnet, but not be integrally formed with the rest of the bonnet. In yet another embodiment a trailing edge of the flap 124 may extend to be coincident with a trailing edge of the bonnet 112.

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In this embodiment the flap 124 is pivotally coupled to the bonnet 112 along a hinge line 140. The flap 124 is further defined by lines of separation 141a, 141b, 141c. These lines of separation are arranged to permit displacement of the flap 124 relative to the bonnet 112 upon activation of the actuator 30.

25

In alternative embodiments the bonnet 112 may be formed such that the flap 124 is separated from the remainder of the bonnet 112 along the lines of separation 141a, 141b, 141c, for example the bonnet 112 may be shaped to incorporate an air intake or air vent or other trim feature which may be formed separately from the bonnet 112 and is inserted into the bonnet or 30 112. The trim feature may be held in place by one or more frangible fixing devices which may be broken upon activation of the actuator.

Figure 9A illustrates a cross sectional view of a trailing portion of a hood or bonnet 212 according to another embodiment of the invention.

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In this embodiment the active section of the bonnet 212 is provided with a bulge, vent or raised section 240 at the trailing edge, part or all of the raised section 240 defines a door or flap 224. A void or cavity 252 is disposed below the raised section 240. An airbag 230 is accommodated 5 within the void or cavity 252.

An inflator 250 is provided to inflate the airbag 230, the inflator 250 may be located in a box section 251 of the bonnet 212, or alternatively may be outside the box (as indicated by phantom lines).

10

Figure 9B illustrates the bonnet 212 in a deployed condition. The flap 224 has pivotally moved about a hinge line 257, defined at the leading edge of the raised section 240. In alternative embodiments the flap 224 may hinge about a different location. The airbag 230 is shown in an inflated condition beneath the flap 224. In this embodiment the airbag 230 has acted as the 15 actuator to deploy the flap 224.

The system may optionally be provided with one or more tethers or restrictors 254, 256. The tethers or restrictors 254, 256 limit the upward travel of the flap 224 and optionally, may also restrict or otherwise constrain at least a portion of the airbag 230 at least in a substantially 20 upward or vertical direction during inflation.

Restricting upward movement of the flap 224 serves to prevent the airbag 230 obscuring the forward field of view for the driver in the event that the flap 224 is deployed.

25 Figure 10A illustrates a perspective view from above of a leading portion of a vehicle 310.

Bonnet or hood 312 comprises a door or flap 324 forming an active protection section disposed toward the rear of the bonnet 312.

30 In this embodiment the flap 324 is substantially flush with the passive section of the bonnet 312. The airbag 330 is disposed beneath the flap 324.

In the deployed state, Figure 10B, the airbag 330 comprises lateral outer portions 372a, 372b which extend beyond the lateral extent of the flap 324 so as to cover outer regions of the bonnet

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312, including the hinge area. Upon inflation of the airbag 330, the flap 324 is arranged to rotate upwardly along a live hinge line 357 towards a deployed position. Optionally, as illustrated, the airbag 330 extends in a longitudinal direction along outer portions of the bonnet 312 and extends at least partially up the frame surrounding the windshield 316, such that the 5 airbag 330 is substantially U shaped. The airbag also extends at least partially over the cowl. A central region 370 of the airbag 330 is disposed beneath the flap 324. Optionally, the central region 370 of the airbag 330 when fully inflated has a maximum elevation which is lower than the maximum elevation of the flap 324. The outer portions 372a, 372b when fully inflated may have a greater maximum elevation than a central region 370 of the airbag 330 and/or that of the 10 flap 324 when in the deployed position.

In this embodiment the airbag 330 is the actuator which deploys the flap 324. Typically the flap 324 and/or airbag 330 may be deployed to a maximum height of 80-100 mm above the normal position of the flap 324 in its undeployed state.

15

Typically the airbag will be deployed and stable within a time period of 50-75ms from the initial impact, or receipt of a deploy signal from the control unit. The airbag 330 may remain inflated at working pressure for a pre-determined period, for example between 250ms and 1000ms from the receipt of a deploy signal from the control unit.

20

In some embodiments a second airbag (not shown) may be deployed from beneath the flap 24. This airbag may be deployed over the vehicle cowl 17, windscreen wipers 18, a lower portion of the windscreen 16 and/or the vehicle structure surrounding the windshield 16 as may be desired.

25

In the foregoing embodiments, the control unit 39 may receive data from a variety of sensors 22 or measurement devices on the vehicle, such as but not limited to fibre optic sensors for detecting a collision, vehicle or wheel speed sensors, mechanical contact sensors or switches activated by deformation of the bumper 14 or other vehicle components, or accelerometers for 30 detecting any significant vibrations in the vehicle structure caused by an impact with an external object and / or for detecting the degree of deceleration experienced as a result of such an impact.

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In some embodiments the flap 24 may be defined in a region of the bonnet disposed adjacent or above an air intake or vent defined within the bonnet.

It can be appreciated that various changes may be made within the scope of the present 5 invention, for example, in the foregoing embodiments the active section A has been described as being hinged to the passive section P but it may be separated therefrom and pivotally coupled to alternative vehicle components. It is envisaged that in some embodiments the bonnet 12 may bend or deform across a region to define a radius rather than fold about a hinge line.

10

Furthermore, in embodiments which include an airbag, the flap need not be hingedly attached to the bonnet assembly or vehicle when deployed, instead, the flap may be attached to the vehicle via tethers. The tethers may be of a length so that when the flap is fully deployed, a planar surface of the flap is presented for optimal pedestrian support. Further, the tethers may be 15 arranged such that an entire surface of the flap is held in contact with the airbag. The tethers may also be of a length to restrain the flap and the airbag to limit obscuration of the view of the driver. For example, the tethers at the rear of the flap may be longer than those at the front. This enables a face of the flap to be partially forward facing, i.e. the deployed flap is inclined downwardly towards the front of the vehicle.

20

In some embodiments the passive protection measures provided in the passive protection section of the bonnet or hood may overlap with the leading edge of the active protection section.

It will be appreciated that in the foregoing embodiments the flap creates a deployable region of 25 the bonnet which is active in the event of a collision with a pedestrian wherein the deployable region forms a moveable energy absorbing section, the deployable region being deformable thereby absorbing at least some of the energy from the contact with the mass of the pedestrian. The deployable region may be deformed or displaced into the space created by deploying the flap into an elevated position above the vehicle component disposed beneath. The control unit 30 39 is arranged to command deployment of the flap in such a way as to be fully deployed and static before contact with the pedestrian, thus providing a stable supporting structure for mitigating pedestrian injury.

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The bonnet therefore comprises a first, passive, section disposed at a fixed distance above the vehicle components disposed beneath and is static and an active section which is moveable such that in normal use it is disposed at a first distance above the vehicle components, in the event of a collision the active section can be deployed such that it is disposed at a second 5 distance greater than the first distance.

It will be appreciated that the foregoing invention may be employed in a vehicle of any design; the height of the leading edge of the bonnet relative to the height of the pedestrian involved in a collision event may be one of a number of factors that determine whether the pedestrian will 10 impact with the active section and/or passive section. This relative height relationship may be one of a number of predetermined criteria used to determine if the active bonnet section should be deployed.

Features described with respect to one embodiment of the invention may be employed with 15 features of other embodiments either in addition or alternative to features of said other embodiments.

It will be recognised that as used herein, directional references such as "top", "bottom", "front", "back", "end", "side", "inner", "outer", "upper" and "lower" do not limit the respective features to 20 such orientation, but merely serve to distinguish these features from one another.

The terms bonnet and hood are used interchangeably throughout and are considered to have equivalent meaning.

25 In the foregoing, the term "pedestrian" has been used to describe a collision between a person and a vehicle. It will be understood that the invention will be of benefit in collisions involving cyclists, motorcyclists and any other mounted road user.

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Claims

1. A vehicle bonnet assembly for managing the energy from an impact with a pedestrian, the assembly comprising a passive pedestrian impact protection section and an active pedestrian impact protection section wherein both passive and active pedestrian impact protection sections are provided on an upper surface of the bonnet assembly and the active pedestrian impact protection section is arranged to be moveable relative to the passive pedestrian impact protection section.

2. The assembly according to claim 1 wherein the active section is moveable from a non-deployed position to a deployed position, whereby when the active section is in the deployed position it provides an increased space for displacement or deformation between the active section and vehicle components therebeneath than when the active section is in the non-deployed position.

3. The assembly according to claim 2 wherein on deployment of the active section, movement thereof is constrained.

4. The assembly according to any of claims 1 to 3 wherein the bonnet assembly is arranged such that when the active section is deployed, the bonnet assembly does not obscure a driver's view from the vehicle.

5. The assembly according to any of claims 1 to 4 wherein the active section is located rearwards of the passive section.

6. The assembly according to any of claims 1 to 5 wherein the active section comprises an actuator for elevating a moveable portion of the bonnet assembly.

7. The assembly according to claim 6 wherein the moveable portion of the bonnet assembly is pivotally coupled to a static section forming part of the passive section.

8. The assembly according to either of claims 6 or 7 wherein the actuator is one of an airbag and a spring loaded mechanism.

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9. The assembly according to any of claims 6 to 8 wherein the actuator is one of pyrotechnically activated and pneumatically activated.

10. The assembly according to any of claims 1 to 9 wherein the bonnet assembly is coupled to a control unit for receiving data input from one or more sensors and/or other measurement devices disposed on the vehicle and is operable to determine, based on predefined criteria whether to deploy the active section.

11. The assembly according to any of claims 1 to 10 wherein the bonnet or hood comprises a hinge pivotally coupling the passive pedestrian impact protection section to the active pedestrian impact protection section.

12. The assembly according to claim 14 wherein the hinge is a live hinge.

13. The assembly according to claim 11 or 12 wherein the hinge defines at least in part a transition between a first passive pedestrian impact protection section and a second active pedestrian protection impact section.

14. The assembly according to any of claims 1 to 13 wherein the passive pedestrian impact protection section comprises a passive static or non-deploying energy absorbing region, the active pedestrian impact protection section comprises a moveable portion moveable between a first, stowed, position and a second, deployed, position, wherein deployment of the moveable portion increases the distance between the moveable portion and vehicle components disposed beneath the active section.

15. The assembly according to any of claims 6 to 14 wherein the moveable portion extends across the entire bonnet or hood.

16. The assembly according to any of claims 1 to 15 in which the active pedestrian impact protection section is disposed towards the rear of the bonnet or hood.

17. The assembly according to any of claims 1 to 16 wherein the active pedestrian impact protection section is provided with an airbag.

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18. The assembly according to claim 17, when dependent upon claim 6, wherein the airbag is the actuator.

19. The assembly according to any of claims 6 to 18 wherein the bonnet assembly comprises one or more tethers to limit or restrict movement of the moveable portion.

20. The assembly according to any of claims 6 to 19 wherein the moveable portion of the bonnet assembly floats or is suspended upon the airbag.

21. The assembly according to either of claims 19 or 20 when dependent on claim 18, wherein the tethers constrict inflation of the airbag across at least a portion thereof.

22. The assembly according to 21 wherein inflation of the airbag is constricted across a central portion thereof, and preferably only the central portion of the airbag is constricted.

23. The assembly according to any of claims 17 to 22 wherein the airbag, when fully inflated, extends beyond the lateral extent of the moveable portion.

24. The assembly according to any of claims 17 to 23 wherein the airbag covers the entire width of the bonnet or hood.

25. The assembly according to any of claims 17 to 24 wherein the moveable portion is disposed over the actuator or airbag and substantially covers at least a central portion of the actuator or airbag when in the deployed position.

26. The assembly according to any of claims 17 to 25 wherein one or more lateral outer portions of the airbag have a greater maximum elevation than a central region of the airbag and/or than the deployable region in the deployed position.

27. The assembly according to any of claims 6 to 26 wherein the moveable portion forms a energy absorbing region which is moveable and/or deformable for absorbing energy in a collision, the moveable portion being moveable and/or deformable into a space created by deployment of the moveable portion.

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28. A vehicle comprising the bonnet assembly of any one of claims 1 to 27.

29. A method of deploying an active region of a vehicle bonnet or hood comprising sensing impact with an object, determining that said object may be one of a pedestrian, cyclist, and motorcyclist, activating an actuator to deploy an active protection region of a vehicle bonnet or hood to an elevated position whilst the passive protection region remains static relative to the vehicle.

30. A vehicle comprising a bonnet or hood having a passive pedestrian impact protection section and an active pedestrian impact protection section substantially as described herein with reference to and/or as illustrated by the accompanying Figures.

31. A vehicle bonnet assembly, a control unit or a method constructed and/or arranged substantially as described herein with reference to and/or as illustrated by the accompanying Figures.