GB2341147A

GB2341147A - Impact absorbing bonnet for a motor vehicle

Info

Publication number: GB2341147A
Application number: GB9819310A
Authority: GB
Inventors: Simon Geoffrey Shale; Stephen Shayler
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1998-09-05
Filing date: 1998-09-05
Publication date: 2000-03-08
Also published as: GB9819310D0

Abstract

A motor vehicle bonnet comprises an outer upper panel 12 and inner lower panel 14. The space between the two panels 12,14 is filled with a polygonal structure comprising a plurality of aligned hexagonal passages 21 in order to absorb energy in the event of a collision with a pedestrian. The passages 12 may run at an angle to the upper and lower plates 12,14. The lower panel 14 may have greater stiffness than the upper panel 12.

Description

2341147 Im13act Absorbing Structure The present invention relates to an

impact absorbing structure for an automotive vehicle, and in particular, but not exclusively, to an impact absorbing structure for a bonnet of an automotive vehicle adapted to absorb the impact of a pedestrian.

Collisions between pedestrians and moving automotiv vehicles are often fatal. Even at low speeds serious injury may be caused to a pedestrian involved in such a collision. The use of the term "pedestrian7 will be understood also to include cyclists and the like who will impact directly onto a vehicle in the event of a collision. In order to reduce such injuries, or at least the seriousness of these injuries, there has been a move in recent years to improve the manner in which vehicles are constructed to absorb such impacts.

In particular the construction of bonnets for motor vehicles has been subject to development. It will be appreciated that the bonnet while absorbing the impact has only a limited opportunity to absorb the impact in the event of a collision with a pedestrian because of the presence of the.

engine block beneath the bonnet. If the impact is not absorbed sufficiently quickly, the pedestrian will become injured upon the engine block.

It is an advantage of the present invention that it reduces the likelihood of injury to a pedestrian in the event of a collision.

According to a first aspect of the present invention, a bonnet for an automotive vehicle comprises an outer upper panel, a lower inner panel, and a first region between the upper and lower panels adapted to absorb an impact, characterised in that the first region comprises a structure of aligned passages.

Preferably, a directional axis of the structure is directed away from a likely direction of impact.

Preferably, the bonnet also comprises a plurality of further regions between the upper and lower panels each comprising a structure of aligned passages adapted to absorb an impact. More preferably, a directional axis of the structure in each further region is provided at an angle to the directional axis of the structure in the first region.

Preferably the directional axis of the structure of the or each further region is disposed at an angle to a longitudinal axis of the bonnet.

Preferably, the directional axis of the structure of the or each further region is disposed at an angle to the top piate of the bonnet.

The passages may be polygonal, circular or elliptical in cross-section.

Preferably, the structure comprises a plurality of sheet members connected together to form the aligned passages. Preferably, the passages are polygonal. More preferably, the polygonal passages are hexagonal.

Alternatively, the structure comprises a plurality of tubular members connected together to form the aligned passages.

Preferably, the lower inner panel has greater stiffness than the outer upper panel.

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

Figure I shows a plan view of a bonnet according to a first embodiment of the present invention; Figure 2 shows a cross sectional view along line 2-2 of the bonnet shown in Figure 1; Figure 3 shows a plan view of a bonnet illustrating further embodiments of the invention; Figure 4 shows a sectional view along line 4-4 of the bonnet shown in Figure 3; Figure 5 shows a sectional view along line 5-5 of the bonnet shown in Figure 3; Figure 6 shows a sectional view along line 6-6 of the bonnet shown in Figure 3; Figure 7 shows a plan view of a bonnet illustrating a still further embodiment of the invention; and Figure 8 shows a sectional view of a bonnet illustrating another embodiment of the invention.

Referring first to Figure 1 and Figure 2, there is shown a front bonnet according to a first embodiment of the present invention. The bonnet 10 comprises an outer upper panel 12 and a lower inner panel 14. The lower inner panel 14 has greater stiffness than the outer upper panel 12. These two panels are joined to one another along side regions by side plates 15, 16 disposed on each side of the bonnet. Each side plate comprises an upright element 17 to space the upper panel from the lower panel, a generally horizontal element 18 which is connected to the lower plate and a depending -51 element 19 which is connected to a lower side edge of the upper plate. The bonnet 10 is located above an engine block 30.

A polygonal structure 20 is located in a cavity within the bonnet defined by the upper plate, the lower plate and the two side plates. In this 5 embodiment, the structure 20 fills the cavity.

The structure 20 comprises a plurality of aligned polygonal passages 21. The passages are defined by a plurality of sheet elements 22, 24 connected together. In the illustrated embodiment, the passages are hexagonal. The axes of the polygonal passages run parallel to one another, parallel to the 10 top and bottom plates and parallel to the side plates 15,16.

A directional axis, defined as an axis running parallel to the axes of the passages comprising the, structure 20, extends in a direction away from a likely direction of impact. This is because if the directional axis extended in the direction of impact the structure may act as a brace to deflect a 15 pedestrian impact rather than as an impact absorption mechanism.

In the illustrated embodiment the passages run from a front 25 of the bonnet to the rear 26. Since any likely impact will have components directed from above, from the side, from the front, or a mixture of the three, the structure will not act as a brace. Instead, the walls 22, 24 of the polygonal passage will buckle under the impact to absorb the impact. Although substantially regular hexagonal passages are shown, it will be understood that the polygonal passages used need not be regular. For example, the generally vertically directed side walls 22 of the passages may 5 be longer than the generally horizontal side walls 24.

Turning to Figures---3 to 6, it will be understood that different arrangements of the passages will provide better impact absorption mechanisms than others, largely dependant on the angle of incidence of pedestrian impact. Accordingly, a bonnet 110 may have more than one 10 polygonal structure located between an upper panel 112 and a lower panel 114, the structures being arranged to provide the optimum impact absorption. One example of such a bonnet 110 is shown in Figure 3, the structures being shown in ghost. The structures are arranged in a generally symmetric fashion about a longitudinal axis 100 of the bonnet 110.

A second structure 120 is shown in Figure 4. The structure 120 again comprises a plurality of aligned polygonal passages. The passages are defined by a plurality of sheet elements 122 connected together. In this embodiment, the axes of the polygonal passages run parallel to one another, but run at an angle to the top and bottom plates 112, 114 and also at an 2o angle to a first side-plate 115. This is because the likely direction of impact is going to be from the front and from the left. The directional axis 150 thus extends in a direction away from the likely direction of impact (arrow A).

A second structure 220 is shown in Figure 5. The structure 220 again comprises a plurality of aligned polygonal passages, the passages being defined by a plurality of sheet elements 222 connected together. In this embodiment, the axes of the polygonal passages run parallel to one another, and in a direction generally perpendicular to the side plates, that is generally parallel to the top and bottom sides 125, 126 of the bonnet 110. However, the axes of the polygonal passages need not run parallel to the top and bottom plates 112, 114 of the bonnet and may run at a slight angle to the plane of the top plate 112. This is because the likely direction of impact is going to be directly from the front. The directional axis 250 thus extends in a direction away from the likely direction of impact (arrow B).

A third structure 320 is shown in Figure 6. The structure 320 comprises a plurality of aligned polygonal passages. The passages are defined by a plurality of sheet elements 322 connected together. In this embodiment, the axes of the polygonal passages run parallel to one another, but run at an angle to the top and bottom plates 112, 114 and also at an angle to a second side plate 116. This is because the likely direction of impact is going to be from the front and from the right. The directional axis 350 thus extends in a direction away from the likely direction of impact (arrow C).

In a still further embodiment (Figure 7) there is shown a front bonnet 410 according to a still further embodiment of the present invention. The bonnet 410 comprises an outer upper panel 412 and a lower inner panel 414. The lower inner panel 414 has greater stiffness than the outer upper panel 412. These two panels are joined to one another along side regions by side plates 415, 416 disposed on each side of the bonnet. A structure 420 is disposed within the bonnei 410. The structure 420 comprises a plurality of aligned polygonal passages, the passages being defined by a plurality of sheet elements 422 connected together. In this embodiment, the axes of the polygonal passages run parallel to one another, and in a direction generally parallel to the side plates 415, 416 of the bonnet 410.

A directional axis 450 thus extends in a direction of a likely direction of impact, that is impact from above. In the event of an impact from directly above the bonnet 410, there is a risk that the structure will act as a brace to deflect a pedestrian impact. In order to prevent this the sheet elements 422 are constructed of thin material that will deflect or buckle easily on impact to absorb a pedestrian impact. Alternatively, the sheet elements 422 may not be secured together along the entirety of their respective lengths to allow for the sheet elements to deflect or buckle more easily on impact.

In Figure 8 there is shown a front bonnet 510 according to another embodiment of the present invention. The bonnet 510 comprises an outer upper panel 512 and a lower inner panel 514. The lower inner panel 514 has a greater stiffness than the outer upper panel 512. These two panels are joined to one another along side regions by side plates 515, 516 disposed on each side of the bonnet. A structure 520 is disposed within the bonnet 510. The structure 520 comprises a plurality of aligned polygonal passages, the passages being defined by a plurality of tubular elements 522 connected together. In the illustrate-d embodiment the tubular elements 522 are of substantially circular cross section and are disposed in a closely packed arrangement running from a front edge of the bonnet to a rear edge of the bonnet. In common with previous embodiments, the tubular elements, and thus the passageways may also run from one side of the bonnet to the other or be disposed. at an angle to the upper and lower panels rather than parallel thereto.

The tubular members may be joined to one another, for example by welding or by adhesive prior to assembly of the bonnet. Embodiments similar to those of previous Figures constructed using tubular members instead of panels are also within the scope of the present invention. For example, the embodiment of Figure 2 may be constructed using tubular members of hexagonal shape. This may be achieved, for example, by the use of tubular members that have been hydroformed to attain the necessary cross-section.

Claims

- 10CLAIMS

1. A bonnet for an automotive vehicle comprising an outer upper panel, a lower inner panel, and a first region between the upper and lower panels adapted to absorb an impact, characterised in that the first region comprises a structure of aligned passages.

2. A bonnet according tc-Claim 1, characterised in that a directional axis of the structure is directed away from a likely direction of impact.

3. A bonnet according to Claim 2, characterised in that the bonnet also comprises a plurality of further regions between the upper and lower panels each comprising a structure of aligned passages adapted to absorb an impact.

4. A bonnet according to Claim 3, characterised in that a directional axis of the structure in each further region is provided at an angle to the directional axis of the structure in the first region.

5. A bonnet according to any previous claim, characterised in that the directional axis of the structure of the or each further region is disposed at an angle to a longitudinal axis of the bonnet.

6. A bonnet according to any previous claim, characterised in that the directional axis of the structure of the or each further region is disposed at an angle to the top plate of the bonnet.

7. A bonnet according to any previous claim, characterised in that the structure comprises a plurality of sheet members connected together to form the aligned passages.

8. A bonnet according to Claim 7, characteried in that the aligned passages are polygonal in cross-section.

9. A bonnet according to Claim 8, characterised in that the polygonal passages are hexagonal.

10. A bonnet according to any of Claims 1 to 6, characterised in that the structure comprises a plurality of tubular members connected together to form the aligned passages.

11. A bonnet according to Claim 10, characterised in that the passages may be polygonal, circular or elliptical in cross-section.

12 A bonnet according to Claim 10 or Claim 11, characterised in that the tubular members are hydroformed.

13. A bonnet according to any previous claim, characterised in that the inner lower panel is stiHer than the upper outer panel.

14. A bonnet for an automotive vehicle substantially as described herein with reference to and as illustrated in any of the accompanying drawings.