GB2394922A

GB2394922A - Motor vehicle with deployable hood

Info

Publication number: GB2394922A
Application number: GB0324426A
Authority: GB
Inventors: Philip Nicholas Holding; Nicolas Jacques Leblanc; Christophe Bastien; Paul Dominic Popley; Kara Louise Laing
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2002-11-06
Filing date: 2003-10-20
Publication date: 2004-05-12
Anticipated expiration: 2023-10-20
Also published as: GB0324426D0; GB0225834D0; GB2394922B

Abstract

The vehicle 10 has a bonnet 12 to cover an engine compartment, the bonnet being hinged at its rearward edge by a hinge mechanism 14 but deployable into a raised or deployed position to allow for a greater clearance from the engine. The bonnet 12 is also attached to the vehicle body structure 11 by a tether 16 which is connected at one end to the bonnet 12 and to the body structure 11 at the other end by means of an inertia controlled reel assembly 15. The tether 16 is used to prevent the bonnet 12 being pushed back into a windscreen 6 of the motor vehicle 10 in the event of a severe frontal impact.

Description

GB 2394922 A continuation (74) Agent and/or Address for Service: Land

Rover Patent Department 53G16/4, Banbury Road, Lighthorne, WARWICK, CV35 ORG, United Kingdom

- 1 Motor Vehicle with deployable Bonnet This invention relates to motor vehicles and in particular to those with bonnets which are deployable in the event of a sensed or potential collision with a pedestrian.

Motor vehicles have to meet strict safety requirements in the event of a frontal impact.

In particular, if the frontal impact involves a pedestrian the head of the pedestrian may 5 impact the central and rear areas of the bonnet. In such a case the bonnet may deform to such an extent that the head of the pedestrian impacts against hard engine points lying under the bonnet.

In order to minimize the severity of head injuries to pedestrians it has been proposed that the bonnet be deployable, i.e. that the rear of the bonnet be lifted during a frontal 10 impact with a pedestrian. One method of lifting the rear of a bonnet is disclosed in EP-A-0992419. An impact sensor in the front bumper triggers a pyrotechnic charge which operates a cylinder used to raise the rear of the bonnet so that the deformable areas of the bonnet are lifted well clear of the engine. However, if the vehicle is involved in an impact with a rigid object after the bonnet has been raised, the bonnet can be torn from its 15 mounting and impact against the windscreen of the vehicle. Such an impact can have serious consequences for occupants of the vehicle. In JP-A-11-263191 a flexible tether is shown for limiting the rearward movement of a deployed bonnet. However, this has to be positioned so that it does not affect normal opening and closing of the bonnet for access to the engine compartment.

20It is an object of this invention to provide a motor vehicle with an improved deployable bonnet arrangement.

According to the invention there is provided a motor vehicle comprising a body structure, a bonnet normally covering an engine or other compartment towards the front of the vehicle, hinge means by which the bonnet is hinged to the body structure, at least one

- 2 actuator means to raise a rear edge of the bonnet from a normal operating position to a raised position when an impact with a pedestrian is sensed to be occurring and at least one tether means arranged to connect the bonnet to the body structure to prevent the bonnet moving rearwardly if the hinge means fails due to a severe frontal impact, wherein the or 5 each tether means is connected to the vehicle body by means of a reel assembly having a reel upon which the tether is wound and locking means to selectively prevent rotation of the reel when the motor vehicle is subject to a deceleration beyond a pre-determined level, the reel assembly being operable to allow the tether to unwind freely from the reel during normal use but prevent unwinding of the tether from the reel in the event of an impact 10 beyond the pre-determined level..

The bonnet may be pivotally fastened to the body structure towards a rear edge of the bonnet by means of two hinge mechanisms, in which case each hinge mechanism may be arranged to provide normal opening of the bonnet in a first position and to facilitate raising of the rear edge of the bonnet when moved into a second position. Alternatively, the 15 bonnet may be connected to the body structure by means of hinge mechanisms located towards a front edge of the bonnet.

Preferably, the reel assembly is fastened to the body structure no further forward than the pivot axis of the front wheels of the vehicle. Conveniently, the reel assembly is fastened a suspension tower used for supporting front suspension springs and/or dampers 20 for the front wheels.

The reel assembly may incorporates an inertia locking device. Alternatively, the reel assembly may be locked by an actuator controlled by a collision sensor.

The invention will now be described by way of example with reference to the accompanying drawing of which:

Fig.1 is a scrap side view of a motor vehicle having a bonnet assembly according to the invention showing the bonnet in a normal position; Fig.2 is a view similar to Fig.1 but showing the bonnet in a raised position in preparation for an impact with a pedestrian; and 5 Fig.3 is a view similar to Figs.1 and 2 but showing the bonnet during a severe frontal impact. With reference to Fig.1, a motor vehicle 10 is shown with a bonnet 12 in the closed position. The front end of the bonnet 12 is retained by a catch 76 mounted on the vehicle body 13 and the rear end of the bonnet 12 is pivotally attached to the vehicle body 13 at 10 each side by a respective hinge mechanism 14. The bonnet 12 is used to cover an engine compartment of the vehicle 10. When the catch 76 is released, the front end of the bonnet 12 can be raised so that the bonnet 12 opens in the normal way by pivoting about a first transverse axis provided by the hinge mechanism 14.

Each hinge mechanism 14 comprises three members, an upper bracket 19 attached 15 to the bonnet 12, a lower bracket 17 attached to the vehicle body 13 and a hinge arm pivotally attached at each end to the lower and upper brackets 17 and 19, this arrangement allowing the rear end the bonnet 12 to be lifted or deployed to the position shown in Fig.2.

The pivotal connection of the hinge arm 18 to the lower and upper brackets 17 and 19 produces two pivot axes at opposite ends of the hinge arm 18 such that at each end, the 20 hinge arm 18 forms an elbow joint with the upper and lower brackets 19 and 17 respectively. At the end of the hinge arm 18 where the hinge arm 18 is connected to the lower bracket 17 there is a first pivot axis about which the bonnet 12 pivots to provide normal opening of the bonnet 12 and at the end of the hinge arm 18 where the hinge arm 18 is connected to the upper bracket 19 there is a second pivot axis about which the 25 bonnet 12 can pivot to move the bonnet 12 to the raised position shown in Fig.2.

During normal operation of the hinge mechanism, the hinge arm 18 is attached to the upper bracket 19 by a clip mechanism (not shown). The clip mechanism is in the form of a pair of punched tabs and is strong enough so that during normal use, the hinge arm 18 is prevented from pivoting with respect to the upper bracket 19 about the second axis and so 5 the hinge mechanism 14 behaves as an ordinary hinge with a single pivot axis, namely the first pivot axis between the hinge arm 18 and the lower bracket 17.

A safety device in the form of a tether 16 is provided at each side of the bonnet 12 to prevent the bonnet 12 impacting against a windscreen 6 of the motor vehicle 10 should the bonnet 12 become detached from the vehicle body 13 due to a failure of the hinge 10 mechanisms 14. Each tether 16 is connected at one end to the respective upper bracket 19 and is attached at the other end to a respective inertia controlled reel assembly 15 which is similar in construction to the type of device used for an inertia reel safety belt. The inertia reel assembly 15 is connected to a strong part of the vehicle body 13, well in front of the windscreen 6. In this particular example it is fastened to a suspension tower 11, i.e. the 15 reinforced part of the body structure where the front suspension springs and/or dampers are supported.

The positioning of the inertia reel assembly 15 is chosen to be sufficiently far forward to provide an effective line of action when required to prevent the bonnet 12 moving rearwards but not so far forward that it is itself moved or damaged by a frontal impact. In 20 most circumstances the inertia reel assembly is best fastened as close to the bonnet line as possible and not further forward than the pivot axis of the front wheels.

The inertia reel assembly 15 has a reel (not shown) upon which the tether 16 is wound and an inertia controlled locking means (not shown) to selectively prevent rotation of the reel when the motor vehicle 10 is subject to a deceleration beyond a pre-determined level.

25 The tether 16 can unwind freely from the reel during normal use but is prevented from unwinding in the event of an impact beyond the predetermined level. Therefore during

- 5 - normal use the tether 16 can feed freely out of the inertia reel assembly 15 to allow for normal opening of the bonnet 12 but in the event of a severe impact the inertia reel assembly 15 automatically locks preventing the tether 16 from feeding out. As is usual in such inertia reel devices, springs (not shown) are provided to automatically rewind the 5 tether 16.

The tether 16 can be made of any suitable material that has sufficient flexibility to be wound onto the reel of the inertia reel 15 and is able to withstand a tensile load of 7000 to 10000N with minimum extension. A preferred material for the tether 16 is inextensible nylon webbing but other materials such as polyester may also be suitable.

10 In order to lift the rear edge of the bonnet 12, two electronically controlled actuators 20 are provided one on each side of the motor vehicle 10. The actuators can be pyrotechnically energized rams, hydraulic rams or any other device suitable for applying a rapid load to the bonnet 12. As shown the actuators are in the form of airbags 20 inflated by means of pyrotechnic charges (not shown). The pyrotechnic charges are fired by an 15 electronic controller (not shown) which receives a signal from a collision sensor (not shown) mounted on the front bumper of the motor vehicle 10.

Operation of the bonnet is as follows. When the collision sensor senses a collision of the type that might involve a pedestrian, the airbags 20 located beneath the rear end of the bonnet 12 are deployed, thereby producing an upward force on the bonnet 12. The 20 upward force causes the rear end of the bonnet to rise whilst the front end pivots on the latch mechanism 76, so that the bonnet adopts the deployed position in which it is raised and inclined with respect to the closed position shown in Fig.1. This deployed position is likely to reduce the risk of serious injury to a pedestrian falling upon the bonnet 12 since the bonnet 12 can now deform to a greater depth before coming into contact with engine 25 components beneath. Also, the inclination of the bonnet helps to deflect a pedestrian away

- 6 from any vehicle windscreen wipers (not shown) and reduces the angle of impact with the windscreen. When the airbags 20 begin to deploy, they exert an upward force on the bonnet 12 which is sufficient to open the clip mechanisms and release the hinge arms 18 from the 5 upper brackets 19 so that the hinge arms 18 are free to pivot with respect to the upper brackets 19 about the second pivot axis. The hinge mechanism can then open out into an extended position in the form of an inverted Z as the rear end of the bonnet 12 is lifted by the deploying airbags 20. During such movement to the deployed position the inertia reel assemblies 15 are not locked because the force of such a collision with a pedestrian is 10 usually insufficient to cause locking. However, if the vehicle 10 then impacts heavily against a rigid object such as a wall 5, the resulting deceleration will cause the inertia reel assemblies 15 to lock and the tethers 16 will prevent the bonnet 12 moving back into contact with the windscreen 6 of the motor vehicle.

It will be noted from Fig.3 that the hinge arm 18 has become detached from the lower 15 bracket 17 due to a failure of a hinge pin (not shown) used to connect these two parts. It will be appreciated that the failure of the hinge mechanisms 14 could be by any means.

This is because an impact with a pedestrian produces a relatively low deceleration but an impact with a wall or other substantial object will produce a very high deceleration. By setting the pre-determined deceleration to be above that normally experienced during a 20 collision with a pedestrian or during a low speed impact the inertia reel assembly 15 can be made to lock only when required.

Although the invention has been described with reference to a rear hinged bonnet it will be appreciated that it is equally applicable to a front hinged bonnet having hinge mechanisms located towards a front edge of the bonnet as shown, for example, in 25 US-A-5697467.

It will be appreciated by those skilled in the art that other means could be used instead of an inertia reel for the tether, for example a reel locked by a solenoid or pyrotechnic actuator, the solenoid or pyrotechnic actuator being controlled by the same controller used to deploy the airbags. It will be further appreciated that the means used to lift the rear end 5 of the bonnet can be of any form and that the invention is not limited to use with lifting and hinge mechanisms as described herein.

Claims

- 8 CLAIMS

1. A motor vehicle comprising a body structure, a bonnet normally covering an engine or other compartment towards the front of the vehicle, hinge means by which the bonnet is hinged to the body structure, at least one actuator means to raise a rear edge of the bonnet from a normal operating position to a raised position when an impact with a pedestrian is sensed to be occurring and at least one tether means arranged to connect the bonnet to the body structure to prevent the bonnet moving rearwardly if the hinge means fails due to a severe frontal impact, wherein the or each tether means is connected to the vehicle body by means of a reel assembly having a reel upon which the tether is wound and locking means to selectively prevent rotation of the reel when the motor vehicle is subject to a deceleration beyond a pre-determined level, the reel assembly being operable to allow the tether to unwind freely from the reel during normal use but prevent unwinding of the tether from the reel in the event of an impact beyond the pre-determined level..

2. A vehicle as claimed in claim 1 in which the bonnet is pivotally fastened to the body structure towards a rear edge of the bonnet by means of two hinge mechanisms.

3. A vehicle as claimed in claim 2 in which each hinge mechanism is arranged to provide normal opening of the bonnet in a first position and to facilitate raising of the rear edge of the bonnet when moved into a second position.

4. A vehicle as claimed in claim 1 in which the bonnet is connected to the body structure by means of hinge mechanisms located towards a front edge of the bonnet.

5. A vehicle as claimed in any preceding claim and including front wheels and wherein the reel assembly is fastened to the body structure no further forward than the pivot axis of the front wheels.

- 9 -

6. A vehicle as claimed in any preceding claim wherein the reel assembly is fastened a suspension tower used for supporting front suspension springs and/or dampers for the front wheels.

7. A vehicle as claimed in any preceding claim in which the reel assembly incorporates an inertia locking device.

8. A vehicle as claimed in any of claims 1 to 6 in which the reel assembly is locked by an actuator controlled by a collision sensor.

9. A vehicle as claimed in any preceding claim in which the tether is made from an inextensible webbing material.

10. A vehicle as claimed in any preceding claim in which the tether has a minimum tensile strength of at least 7000N.

11. A motor vehicle substantially as described herein with reference to the accompanying drawings.