GB2178703A

GB2178703A - A vehicle bumper

Info

Publication number: GB2178703A
Application number: GB08519816A
Authority: GB
Inventors: John Arthur Amner; Roy Goodrum
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1985-08-02
Filing date: 1985-08-07
Publication date: 1987-02-18
Also published as: GB2178703B; GB8519432D0; GB8519816D0

Abstract

A vehicle bumper has an outer skin 10 of plastics, an internal reinforcement 12 also of plastics and a foam core which bonds the reinforcement to the outer skin and provides shock absorption between the outer skin and the reinforcement. The reinforcement also provides the mounting means by which the bumper is mounted on the vehicle. <IMAGE>

Description

SPECIFICATION A vehicle bumper This invention relates to a vehicle bumper made of plastics materials. The bumper should be able to absorb low speed impacts without any permanent deformation.

A plastics skin does not have the same strength as a steel skip, and thus bumpers where a plastics outer skin is used require reinforcement in some way in order to give them the required strength. In some bumpers this is done by forming the interior of the bumper into a box section.

According to the present invention there is provided a vehicle bumper comprising a plastics skin, a foam core and a plastics reinforcement member, with the foam core being bonded both to the inside of the skin and to the reinforcement member and being able to compress to assist in absorbing impacts on the skin, and wherein the reinforcement member carries fastening means for fastening the bumper on a vehicle.

The use of a plastics reinforcement member simplifies the task of bonding the body of foam to the reinforcement member. Provided the correct materials are chosen, bonding will take place automatically when the foam material is introduced into the bumper.

The reinforcement member is preferably of convoluted form to increase its strength and help to provide sufficiently rigidity for the reinforcement member also to provide the attachment points by which the bumper is attached to the vehicle. Furthermore, the convolutions of the reinforcement member can be used to reduce the amount of foam required in the bumper, and thus to reduce the weight of the bumper.

The reinforcement member is preferably bonded to the foam over its whole length, lies within the envelope of the skin over a major part of the length of the member, and lies outside the envelope over minor parts of the length of the member, the parts where the reinforcement member lies outside the envelope serving as attachment points for attaching the bumper to a vehicle.

The term 'envelope of the skin' refers to the volume which is defined within the crosssection of the bumper, the cross-section being bounded by an imaginary string being drawn taut around a crnss-section of the bumper.

The reinforcement member preferably has a base surface which lies flush with the exposed foam surface at the back of the bumper, and pockets which extend from the base surface into the body of foam to reduce the volume of foam required to fill the space between the reinforcement and the plastics skin.

The reinforcement member preferably has raised regions extending from the opposite side of the base surface to the pockets, which raised regions are provided with mounting members by which the bumper can be attached to the vehicle. For example threaded bolts or studs can be permanently mounted in the raised regions. The raised regions will normally extend outside the envelope of the plastics skin.

The bumper preferably has a main portion which extends across the width of the vehicle and two opposite end portions which extend a short distance along the sides of the vehicle. The reinforcement member preferably extends across the main portion and into both side portions.

The body of foam is preferably self-skinning polyurethane foam. The skin and the reinforcement can be, for example, modified polypropylene or polycarbonate.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a view on a horizontal section through part of a bumper in accordance with the invention, on the line I-I from Fig. 2; Figure 2 is a rear view of the bumper shown in Fig. 1, seen in the direction of the arrow A from Fig. 1; Figure 3 is a cross-section through the bumper of Figs. 1 and 2, of the lines Ill-Ill; Figure 4 shows a section through the bumper on the lines IV-IV from Figs. 1 and 2, mounted on a vehicle; and Figure 5 is a perspective view from the rear of a bumper in accordance with the invention.

The bumper has a skin 10 which is a plastics moulding, and a reinforcement member 12 which is also a plastics moulding. Both of these will be relatively rigid mouldings which could conveniently be injection moulded. Modified polypropylene or polycarbonate are suitable materials. Between the skin 10 and the reinforcement member 12 there is a body of foam 14. This foam can be a self-skinning polyurethane foam which will bond directly to the plastics materials of the skin 10 and the reinforcement member 12. As can be seen in Figs. 1 and 5, the foam 14 is exposed at the end 16 of the reinforcement member 12 and also extends over and encapsulates the extreme end of the reinforcement member. The foam thus needs to be self-skinning.

The plastics skin 10 forms the visible outer surface of the bumper and is generally in a Cshape as can be seen from Figs. 3 and 4.

The reinforcement has a number of pockets 20 which extend inwardly into the bumper relative to a base surface 22. The base surface is defined by lateral flanges 24 of the reinforcement member, as can be seen in Figs. 2, 3 and 4. Fig. 1 shows that the pockets 20 project below the base surface 22 a distance more than half the distance from the base surface to the skin 10. Between the pockets 20, the surface of the reinforcement member is coincident with the base surface 22.

A raised portion 24 is also formed in the reinforcement member, and the reverse side of this raised member is filled entirely with foam 14. Two threaded bolts 26 are fixed in this raised portion and are backed up by a metal plate 28. The fact that the foam 14 extends right into this raised portion 24, and is bonded over the whole of the interior surface of the raised portion ensures that the mounting face of the raised portion 24 and the bolts 26 are quite stable.

Fig. 3 is a section on the centre line of the bumper; Figs. 1 and 2 each show one half of the bumper. There will be two raised regions 24, one at either side for securing the bumper (see Fig. 5). Additionally there may be fastening means for attaching the ends of the side portions 40 of the bumper to the vehicle.

Fig. 4 shows the bumper fitted to a vehicle with the studs 26 bolted to a vehicle body member 30 in front of a cooling system radiator 32. The vehicle bonnet is shown at 34 and a front apron at 36.

The foam inside the bumper absorbs energy on impact and gives a reduced bumper deflection, relative to conventional bumpers, upon impact. This means that the forward or rearward projection of the bumper can be less than would otherwise be the case, and the energy absorbing characteristics avoid the need to mount the bumper on a beam spanning across the front of the vehicle. The bumper as shown can accept a 4 kph impact at the centre line and a 2.5 kph impact at the corners, without any permanent distortion.

Claims

1. A vehicle bumper comprising a plastics skin, a foam core and a plastics reinforcement member, with the foam core being bonded both to the inside of the skin and to the reinforcement member and being able to compress to assist in absorbing impacts on the skin, and wherein the reinforcement member carries fastening means for fastening the bumper on a vehicle.

2. A vehicle bumper as claimed in Claim 1, wherein the reinforcement member extends substantially the full width of the bumper, is bonded to the foam over its whole length, lies within the envelope of the skin over a major part of the length of the member, and lies outside the envelope over minor parts of the length of the member, the parts where the reinforcement member lies outside the envelope serving as attachment points for attaching the bumper to a vehicle.

3. A bumper as claimed in Claim 1 or Claim 2, wherein the reinforcement member has a base surface which lies flush with an exposed foam surface at the back of the bumper, and pockets which extend from the base surface into the body of foam to reduce the volume of foam required to fill the space between the reinforcement and the plastics skin.

4. A bumper as claimed in any preceding claim, wherein the reinforcement member has raised regions extending from the opposite side of the base surface to the pockets, which raised regions are provided with mounting members by which the bumper can be attached to the vehicle.

5. A bumper as claimed in Claim 4, wherein threaded bolts or studs are permanently mounted in the raised regions.

6. A bumper as claimed in Claim 4 or Claim 5, wherein the raised regions extend outside the envelope of the plastics skin.

7. A bumper as claimed in any preceding claim, wherein the bumper has a main portion which extends across the width of the vehicle and two opposite end portions which extend a short distance along the sides of the vehicle.

8. A bumper as claimed in Claim 7, wherein the reinforcement member extends across the main portion and into both side portions.

9. A bumper as claimed in any preceding claim, wherein the body of foam is a selfskinning polyurethane foam.

10. A bumper as claimed in any preceding claim, wherein the skin and the reinforcement are of modified polypropylene or polycarbonate.

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

CLAIMS Amendments to the claims have been filed, and have the following effect: Claims 1,2 above have been deleted or textually amended.

New or textually amended claims have been filed as follows: Claims 3-11 above have been re-numbered as 2-10 and their appendancies corrected.

1. A vehicle bumper comprising a plastics skin, a foam core and a plastics reinforcement member, with the foam core being bonded both to the inside of the skin and to the reinforcement member and being able to compress to assist in absorbing impacts on the skin, and wherein the reinforcement member carries fastening means for fastening the bumper on a vehicle, extends substantially the full width of the bumper, is bonded to the foam over its whole length, lies within the envelope of the skin over a major part of the length of the member, and lies outside the envelope over minor parts of the length of the member, the parts where the reinforcement member lies outside the envelope serving as attachment points for attaching the bumper to a vehicle.