Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF TllE INVENTION
The invention relates to energy managing or controlling
devices, hereinafter referred to as energy controlling devices,
for fittin~ to vehicles (which term is intended -to include land,
water and hovercraft vehicles) and to stationary structures, to
act as fenders or bumpers for controlling the energy of impact.
It is known to construct bumpers from elastomeric material.
~Iowever, the use of such material can present problems in that it
is comparatively difficult to produce an acceptable surface
finish on the elastomeric material without the use of high grade
molding techniques. Such techniques require expensive molds,
and of course molds must be provided for each differently shaped
fender.
An object of the invention, therefore, is to provide an
improved bumper which at least reduces these problems.
Another object of the invention is to provide an improved
method of making a bumper.
SUMMARY OF THE INVENTION
According to the invention, there is provided an energy
controlling device, comprising a molded channel-shaped base
portion made of elastomeric material with the outside of the
bottom of the channel defining an impact receiving face and with
substantially parallel reinforcing compression-resistant filaments
embedded in the elastomeric material, each filament running
continuously from adjacent the distal edge of one side wall of
the channel to the impact receiving face, around the bottom of the
channel and then within the other side wall to adjacent the distal
edge of that side wall, the filaments forming with the elastomeric
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terial a composite beam s-tructure to which -tl~e compression-
r~ sistance oI ~he embedded ~ilaments imparts a high resistance
to bending of the said side walls in response to impacts
received on said face, and an outer, separately molded, covering
: 5 of material having a variable thickness and cross-sectional
shape attached to at least part of the base portion to provide
a predetermined finish, size and non-uniform shape for the device.
According to the invention, there is also provided a method
of manufacturing an energy controlling device, comprising the
steps of moldin~ a base portion made substantially of elastomeric
material into channel shape and with less than the size of the
final device, including embedding reinforcing compression-
resistant filaments into the elastomeric material, the filaments
running continuously from adjacent the distal edGe of one side
wall of the challnel to the bottom of the channel, around the
bottom of the ch~nnel and then within the other side wall to
adjacent the distal edge of that side wall, the filaments forming
with the elastomeric material a composite beam structure to
which the compression-resistance of the embedded filaments
imparts a hi~h resis-tance to bending of the said side walls in
response to impacts received on the outside of the bottom of the
channel, and then separately forming onto the base portion an outer
covering of material having a variable thickness and cross-section
shape to provide the device with the required final shape and size.
BRIEF DESCRIPTION OF THE DRAWINGS
Energy controlling devices embodying the invention, and
methods employing the invention of making such devices, will now
be described with reference to the accompanying diagrammatic
drawings in which:
Figures 1 and 3 are plan and cross-sectional views of
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one of the devices in a partially completed form, ~ig.2 being an
enlarged section on the line II-II of Fig.l; and
Figures 3 and 4 are plan and cross-sectional views of the
completed device ready for fitment to the vehicle or other struc-
ture to be protected, Fig.4 being an enlarged section on the line
IV-IV of Fig.3.
DESCRIPTION OF PREFERRED EMBODIMENTS
The base portion 5 (Figs.l and 2) of the energy controlling
device, which may take the form of a fender for a motor vehicle for
example, is formed principally of elastomeric material such as
rubber. The base portion is designed to provide the impact absorb-
ing qualities required in the final fender and it is molded,
possibly under conditions of considerable heat and pressure, into
approximately the required final shape of the fender though having
a smaller size overall than the final size. No attention need be
given to ensuring that the outer surface of the base portion 5 has
a smooth surface finish. As shown in Figure 2, the base portion
advantageously has a "U"-shape and in use is mounted to receive
impacts occurring in the direction of the arrows"A".
The molded base portion, preferably in an at least partially
vulcanized form so that it will retain its shape, is then placed
in a second mold by means of which an outer skin 6 (Figs.3 and 4)
of polyurethane foam (or similar material) is applied as by
injection-molding. The polyurethane foam bonds to the already
formed base portion 5. It is a relatively simple matter to ensure
that the outer surface of the polyurethane foam skin 6 has the
desired quality and smoothness for the finished product.
The process is advantageous for a number of reasons.
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Because the final shape and size o:E the product can be controlled
by the shape and thickness of the polyurethane foam, it is possible
to use the same base portion 5 for bumpers or fenders of different
final shape and size, with the final shape and size being in each
case determined by the outer skin of the polyurethane foam. Thus,
it may be possible to manufacture the base portion in only a few
basic sizes to cover a whole range of bumpers or fenders. This
provides a very considerable saving in the heavy capital cost involv~
ed in making molds for the base portion 5. Since the polyurethane
foam is not s~bject to either high pressure or hiqh temperature, it
can therefore be applied using low cost molds and a low cost injec-
tion molding machine.
For the same reasons, the process described below is also
advantageous in that it enables prototypes of new bumpers or fenders
to be manufactured quickly and inexpensively.
Since the final surface finish of the bumper or fender is
determined by the polyurethane foam and is easily controllable, the
quality of the surface finish of the base portion 5 is not important
and there is thus much less rejection of imperfectly formed elasto-
meric material, and this is important because the material may beexpensive.
The process described is particularly applicable where the
elastomeric material has embedded filament layers 8 (see Fig 2) as
disclosed in our co-pending Canadian Application No.176,659 (Patent
No.1005094). As there disclosed in detail, the filaments are bonded
or mechanically locked in the elastomeric material to form a
composite beam structure and have such cross-section area and
modulus of elastitity as principally to take the
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compressive forces when the material is bent, in response to an
impact to be absorbed, in a direction which places at least some of
the filaments in compression. The use of the outer skin portion
as herein described enables the filament layers 8 to be moved
further outwards towards the surfaces of the elastomeric material
than would otherwise be possible (and they may actually be embedded
in the surfaces of the elastomeric material) since a protective
covering of the elastomeric material is no longer required.
Furthermore, the provision of the outer skin portion enables the
required mass of the elastomeric material to be substantially
reduced giving an advantageous reduction in curing time. In each
of the filament layers 8, the filaments are parallel and run from
the distal end of one leg of the U towards the impact receiving base
of the U, around the base of the U, and then along the other leg of
the U to its distal end, all as disclosed more fully in the Applica-
tion referred to above.
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