GB2287435A

GB2287435A - A motor vehicle bumper with an air chamber

Info

Publication number: GB2287435A
Application number: GB9403976A
Authority: GB
Inventors: Alan Robert Harrison; Steve Causey
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1994-03-02
Filing date: 1994-03-02
Publication date: 1995-09-20
Also published as: GB9403976D0

Abstract

A motor vehicle bumper has an air chamber 16 mounted in a position where it will extend across the front of the vehicle. The chamber 16 is blow-moulded and self supporting and has apertures 18, 20 which are permanently open to the outside atmosphere. On impact, energy will be absorbed by compression of the air contained within the chamber which is only allowed to escape slowly through the apertures 18, 20. A skin or facsia moulding 22 forming the exterior of the bumper may be fixed directly to the air chamber, or may have an intermediate layer of a foam composition (24, Fig 4). <IMAGE>

Description

A MOTOR VEHICLE BUMPER This invention relates to a motor vehicle bumper which is particularly intended for absorbing the energy of impacts.

According to the present invention there is provided a motor vehicle bumper incorporating an air chamber extending the width of the bumper, the air chamber being formed as a blow moulding with self-supporting walls and having at least one aperture through which the interior of the chamber communicates with the atmosphere at all times.

A bumper with these features is easy to manufacture. It is preferred to have a single air chamber extending the full width of the bumper and extending therefore the full width of the vehicle on which the bumper is to be mounted.

In the event of an impact the walls of the chamber will be compressed and air will be expelled from the aperture or apertures which communicate with the atmosphere. By suitably dimensioning these apertures, the rate at which air can be expelled can be controlled to give any desired degree of energy absorption.

The chamber preferably has two apertures, one at each end.

The chamber may be mounted behind a bumper front skin, and the front skin may have structural strength.

In a preferred form the chamber is bonded to the skin, and a layer of foam may be provided between the chamber and the skin, possibly by a "foam in place" technique.

In yet another embodiment the skin may be moulded integrally with the chamber.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view, from behind, of a motor vehicle bumper in accordance with the invention; and Figures 2, 3 and 4 are cross-sections through the bumper of Figure 1, showing three different possible constructions in accordance with the invention.

Figure 1 shows a bumper having a transverse portion 10 and two side portions 12 and 14. Extending across the transverse portion 10 is an air chamber 16. The air chamber 16 is a single blow moulded body which is generally rectangular in cross-section with selfsupporting walls, ie the chamber retains its shape without the aid of a differential pressure between the inside and the outside of the chamber.

The chamber has air egress points 18, 20 which are simply openings into the interior volume of the chamber. There may be one, two or more openings, The cross-sectional area of each opening can be chosen to give a desired flow rate through the opening. These openings may be formed at the time of manufacture by suitably trimming the ends of the parison from which the chamber is blow-moulded.

A skin or fascia moulding 22 forms the exterior surface of the bumper. This skin can be formed in any known manner to give a cross-sectional shape substantially as shown in Figure 2, 3 or 4. However in one embodiment the chamber 16 and the skin 22 can be integrally moulded, ie they can be one and the same component.

Figure 2 shows the chamber 16 in position behind the skin 22. The chamber and the skin can be connected to one another in any suitable manner, and it should be noted that small punctures or openings formed in the wall of the chamber can be tolerated. The chamber can therefore be mounted to the bumper by wall-piercing fastenings but it is preferred to connect the chamber to the skin by adhesive or some bonding method.

Figure 4 shows one particular example of this where the chamber 16 is placed in the desired position relative to the skin 22, and the space between the two components is filled with a foam composition 24 which bonds to the facing surfaces of both components.

A bumper which incorporates an air chamber as described here can be particularly useful for absorbing low speed/low energy impacts, particularly impacts between a vehicle and a pedestrian.

An air chamber as described here can be the only energy absorbing construction in a bumper, or can be combined with one or more other energy absorbing constructions.

This may be required, for example, when one construction is suitable for absorbing low energy impacts and another is designed to absorb high energy impacts.

The air chamber 16 can be blow-moulded from any suitable material.

The use of the chamber described has the advantages of low cost and simplicity since the chamber itself is made in one operation and has no separate parts.

The bumper may be able to be repaired by re-inflation with positive air pressure after a low speed impact to minimise repair costs.

Claims

1. A motor vehicle bumper incorporating an air chamber extending the width of the bumper, the air chamber being formed as a blow moulding with self-supporting walls and having at least one aperture through which the interior of the chamber communicates with the atmosphere at all times.

2. A bumper as claimed in Claim 1 which has a single air chamber extending the full width of the bumper.

3. A bumper as claimed in Claim 1 or Claim 2, wherein the chamber has two apertures, one at each end.

4. A bumper as claimed in any preceding claim, wherein the chamber is mounted behind a bumper front skin, and the front skin has structural strength.

5. A bumper as claimed in Claim 4, wherein the chamber is bonded to the skin.

6. A bumper as claimed in Claim 4 or Claim 5, wherein a layer of foam is provided between the chamber and the skin, to bond the chamber to the skin.

7. A bumper as claimed in Claim 4, wherein the skin is moulded integrally with the chamber.

8. A motor vehicle bumper substantially as herein described with reference to any one embodiment shown in the accompanying drawings.