Vehicle bonnets

Abstract: A vehicle bonnet assembly includes a bonnet (10) hinged to the vehicle body adjacent one edge (12) and having releasable catch means (25) adjacent an opposite edge (20), the bonnet (10) being hinged to the vehicle body in a manner which will permit rearward movement of the bonnet (10) when an impact is applied to the leading edge (12) thereof, a lifting mechanism (11, 26) being provided to lift the trailing edge (20) of the bonnet (10) in response to rearward movement of the bonnet (10).

Description: The present invention relates to vehicle bonnets and in particular bonnets for motor cars. In modern motor car design, for visibility, aerodynamic and styling reasons, it is desirable that the bonnet line is kept as low as possible. As a result, there is generally very little clearance between the bonnet and the engine bay contents of the motor car. Consequently, the bonnet will provide very little cushioning effect when impacted by a pedestrian during an accident. JP-A-58211975 discloses a vehicle bonnet assembly corresponding to the preamble of claim 1 which upon impact with a pedestrian will raise the trailing edge of the bonnet to cushion the impact. According to one aspect of the present invention, a vehicle bonnet assembly includes a bonnet, said bonnet being hinged directly or indirectly to the vehicle by means of a pair of hinge mechanisms located adjacent to the leading edge of the bonnet, the hinge assembly permitting rearward movement of the bonnet when an impact is applied to the leading edge thereof and means to lift the trailing edge of the bonnet in response to rearward movement of the bonnet characterised in that each hinge mechanism comprises a link pivotally connected at one end directly or indirectly to the vehicle and at the other end to the bonnet, and a strut pivotally connected at one end to the vehicle coaxially of the pivotal connection of the link, and at the other end to the bonnet at a position spaced forwardly of the pivotal connection to the link, the effective length of the strut being adapted to shorten when an impact load is applied to the leading edge of the bonnet. In accordance with the present invention, upon impact with a pedestrian, the vehicle bonnet is lifted to provide a clearance, so that the bonnet may deform to cushion the impact. According to a preferred embodiment of the invention means is included to prevent rearward movement of the bonnet until the impact load exceeds a predetermined limit, so that the lifting mechanism will not be triggered inadvertently or maliciously. The invention is now described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a perspective view of a bonnet assembly in accordance with the present invention; Figure 2 is a longitudinal cross-sectional view of the bonnet assembly illustrated in Figure 1; Figure 3 is a perspective view of a modification to the bonnet assembly illustrated in Figure 1; In the bonnet assembly illustrated in Figures 1 and 2, the bonnet 10 is hinged to the vehicle structure by means of a pair of hinge mechanisms 11 which are located adjacent the leading edge 12 of the bonnet 10. Each hinge mechanism 11 comprises a first link 13 mounted at one end to the vehicle structure by means of pivot 14 and at the other end to the bonnet 10 by pivot 15. A second link 16 is attached to the vehicle structure by means of pivot 14. The second link 16 is connected to the third link 17 by means of an energy absorbing structural hinge 18, the third link 17 being attached to the bonnet 10 by means of pivot 19, the pivot 19 being spaced from pivot 15 towards the leading edge 12 of the bonnet 10. The links 16,17 thereby provide a strut between the vehicle structure and the bonnet, the length of which may be reduced by pivoting of one link relative to the other. structure and the bonnet, the length of which may be reduced by pivoting of one link relative to the other. The energy absorbing structural hinge 18 may be a torque loaded frictional joint, a structural failure joint, a shear restraint, any combination thereof or any other structural joint which will permit relative pivoting of links 16 and 17 when loads in excess of a predetermined magnitude are applied thereto. Spring means may be provided on the pivot 14 in conventional manner, to assist in opening and closing the bonnet 10. Catches (not shown) are provided adjacent the trailing edge 20 of the bonnet 10, to retain the bonnet 10 in the closed position. Under normal operation, when the bonnet 10 is opened and closed, the links 16 and 17 will remain in fixed relationship and the bonnet 10 will pivot about the pivot 14. As illustrated in Figure 2, if the vehicle is in collision with a pedestrian, the impact of the pedestrian on the leading edge 12 of bonnet 10 will cause hinge 18 to give, so that the links 16 and 17 move relative to one another, causing the leading edge 12 of the bonnet 10 to move rearwardly and downwardly as shown in broken line in Figure 2. The catches adjacent the trailing edge 20 of bonnet 10 are arranged to release the bonnet 10 on rearward movement thereof, so that the trailing edge 20 will be lifted upwardly. The upward movement of the trailing edge of the bonnet 10 will increase the clearance between the bonnet 10 and the engine thereunder, thus increasing the cushioning effect thereof. Furthermore, the energy absorbing hinge 18 will control rearward movement of the bonnet 10 so that the initial impact on the leading edge 12 of the bonnet 10 is cushioned, thereby reducing injuries to the pedestrian from this initial impact. In the modification illustrated in Figure 3, the catches 25 adjacent the trailing edge 20 of bonnet 10 are mounted on links 26. Each catch 25 is pivotally mounted to one end of a link 26, the other end of the link 26 being connected to the vehicle body 27 by pivot 28. The pivots 28 have torque limiting mechanisms for example, a non-return ratchet, a torque loaded frictional joint, a shear restraint or any combination of the above, so that for normal opening or closing of the bonnet 10, the catches 25 will remain in place as illustrated in full line in Figure 3. However, upon rearward movement of the bonnet 10 following an impact with a pedestrian, the catches 25 will remain engaged, links 26 pivoting upwardly to control lifting of the trailing edge 20 of bonnet 10, as illustrated in broken line in Figure 3. Various modifications may be made without departing from the scope of the invention. For example in the embodiment illustrated in Figure 1, the links 16 and 17 may be replaced by a telescopic strut which will reduce in length upon impact with a pedestrian, causing the leading edge of the bonnet to move downwardly and rearwardly and the trailing edge to lift. The telescopic strut may include means to prevent shortening of the strut before a predetermined impact load is reached, and may also include damping means to cushion the initial impact.

Claims: A bonnet assembly including a bonnet (10), the bonnet (10) being hinged directly or indirectly to the vehicle by means of a pair of hinge mechanisms (11), the hinge assembly permitting rearward movement of the bonnet (10) when an impact is applied to the leading edge (12) thereof and means (11; 26) to lift the trailing edge (20) of the bonnet (10) in response to rearward movement of the bonnet (10) characterised in that said hinge mechanisms are located adjacent to the leading edge (12) of the bonnet (10), and each hinge mechanism (11) comprises a link (13) pivotally connected at one end directly or indirectly to the vehicle and at the other end to the bonnet (10), and a strut (16, 17) pivotally connected at one end to the vehicle coaxially of the pivotal connection (14) of the link (13), and at the other end to the bonnet (10) at a position (19) spaced forwardly of the pivotal connection (15) to the link (13), the effective length of the strut (16, 17) being adapted to shorten when an impact load is applied to the leading edge (12) of the bonnet (10). A bonnet assembly according to Claim 1 characterised in that the effective length of the strut (16;17) will shorten when the impact load applied to the leading edge (12; 31) exceeds a predetermined limit. A bonnet assembly according to Claim 1 or 2 characterised in that the strut (16, 17) of each hinge mechanism (11) comprises a second link (16) pivotally attached directly or indirectly to the vehicle and a third link (17) pivotally attached to the bonnet (10), the second and third links (16, 17) being joined by an energy absorbing hinge (18). A bonnet assembly according to Claim 3 characterised in that the energy absorbing hinge (18) comprises a torque loaded frictional joint, a structural failure joint and/or a shear restraint. A bonnet assembly according to Claim 4 characterised in that the strut (16, 17) of each hinge mechanism (11) comprises a telescopic strut. A bonnet assembly according to any one of the preceding claims characterised in that catch mechanisms (25) are provided towards the trailing edge (20) of the bonnet (10) to maintain the bonnet (10) in its closed position, the catch mechanisms (25) being adapted to release the bonnet (10) upon rearward movement of the bonnet (10). A bonnet assembly according to Claim 6 characterised in that each catch mechanism (25) is pivotally located at one end of a link (26), the other end (28) of the link (26) being pivotally connected to the vehicle body (27) such that upon rearward movement of the bonnet (10), the catch mechanisms (25) will pivot upwardly on their links (26), to assist in lifting the trailing edge (20) of the bonnet (10). A bonnet assembly according to Claim 7 characterised in that the catch mechanism links (26) are pivotally connected to the vehicle body (27) by means of pivots (28) including torque limiting mechanisms. A bonnet assembly according to Claim 8 characterised in that the torque limiting mechanisms comprise a non-return ratchet, a torque loaded friction joint and/or a shear restraint.

Inventors: CADY JOHN BILLINGTON, FISHER STEPHEN ANDREW, HOWARD MARK SHANE, LLOYD ROBERT CHARLES WILLIAM, THOMAS ALAN VAUGHAN, CADY, JOHN BILLINGTON, FISHER, STEPHEN ANDREW, HOWARD, MARK SHANE, LLOYD, ROBERT CHARLES WILLIAM, THOMAS, ALAN VAUGHAN
Applicants: JAGUAR CARS, JAGUAR CARS LIMITED
Application year: 1992
Main classification: B62D25
IPC codes: B62D25, B60R21, E05D11