ROTOR DE FREIN EN COMPOSITE

COMPOSITE BRAKE ROTOR

Abrégé anglais

A lightweight disc brake rotor having an aluminum core and wear-resistant
faces. The core has two riveted discs with matching vent grooves on each inner
face
and raised barbs on each outer face. In a mould, lower and upper layers of
brake-
friction-like powdered media including mineral compounds such as silica sand
and
metallic oxides mixed with a resin such as phenolic liquid and/or powder, are
heat and
pressure moulded onto each outer barbed face of the core.

Revendications

I CLAIM:
1. A rotor comprising:
a core, the core comprising two discs, each disc having an inner and
outer face, central holes, and a plurality of holes for rivets;
each inner face having a plurality of vent grooves;
each outer face having a plurality of barbs;
a plurality of rivets through the holes in the two discs;
a layer of wear resistant material moulded-on to each outer face
and into which material the barbs are embedded.
6

Description

FIELD OF THE INVENTION
The present invention is in the field of disc brakes for vehicles and more
particularly the disc brake rotor.
BACKGROUND OF THE INVENTION
The search for vehicular fuel efficiency includes reducing vehicle weight
which has multiple spin-off benefits such as improved braking, handling and
ride
comfort. A brake rotor moves and rotates with the wheel. The vehicle is slowed
by brake friction pads bonded to a plate back that are squeezed against the
rotor's
faces by a hydraulic caliper to create friction which converts the rotating
kinetic
energy of the moving vehicle into heat thus slowing the vehicle. The
traditional
cast iron disc brake rotor is very heavy. Many attempts have been made to
replace it with other lighter materials but none have reached the mass market.
SUMMARY OF THE INVENTION
The instant disc brake has a thick lightweight core with thin and hard outer
facings. Two flat aluminum discs each has one inner face with matching vent
grooves radially spaced from a centre hub hole to the outer perimeter. The
second
outer face is populated with raised barbs. The discs are riveted together vent
side in
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to form the rotor core. A powdered media with hard wearing compounds and
curable resin is heat and pressure moulded onto each of the outer barbed faces
forming the desired hard facing.
In one embodiment a mixture of suitable materials such as sand (silica),
resin, fibres and fibre mesh (the media) is levelled in a mould (or mold), the
rotor
core laid on top, followed by a second layer of the mixture. In a press the
sandwich
is simultaneously heated and compressed embedding the barbs, melting the resin
and curing it whereby the mixture becomes hard. In a second embodiment the
mixture is compressed cold and the resulting sandwiches stacked and heated in
an
oven to cure the resin.
The powder moulding process described is universally used in making disc
brake pads and abrasive wheels. In brake pads the mixture called 'friction' in
the
trade, is heat- and pressure cured onto a steel backing plate with or without
barbs.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a face view of one aluminum disc showing the radially spaced
cooling vents;
Figure 2 shows the other side of the same disc with concentric rings of raised
barbs;
Figure 3 shows a side or edge view of two aluminum discs assembled with the
vent
grooves arranged mirror-like and secured with aluminum pins riveted into the
countersinks thereby creating a one piece rotor core;
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Figure 4 shows the barbed face where the barbs are arranged in crosswise rows.
The
countersinks filled with the riveted pins are also shown to be burred;
Figure 5 is a perspective view of the brake rotor sandwich with the top hard
face
separated for clarity. Inner and outer ends of a vent are also shown;
Figure 6 shows a cross-section with a single barb is embedded in the
compressed media;
Figure 7 shows a fibre mesh element to be included in media layer;
Figure 8 shows the vents branched at the outer ends to provide better surface
coverage for
better cooling;
Figure 9 shows smaller and more numerous vents
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, aluminum discs 1 have each face processed
differently, one face of each disc has vent grooves 2 (Figs 1, 2, 4, 5, 7, 8).
The
vents grooves are configured for centrifugal air flow from the centre 6
outwards.
The vent faces face each other to form cooperative single vents.
The second face of each disc has barbs 3, 4 (Figs 2, 4, 5, 6) to engage a
layer
of media 5 that will form hard surface 15 on rotor core 20.
In Fig 3 matching holes 7 for aluminum pins 10 passing through both discs 1
and whose ends are riveted 11 into into their respective countersinks 8. One
end of
the pin 10 can be pre-formed to fit countersink 8 and the second pin end then
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riveted in place into the second countersink. This riveting together of discs
1
completes rotor core 20 with exposed burred faces.
By way of background, barbs 3 (as disclosed in Canadian Patent 1,330,521
and related USA Patent 5,376.410, both to MacKelvie, the present inventor-
applicant) are formed with toothed blades actuated in a tool (such as
disclosed in
Canadian Patents 1,330,521 and 2,475,801, and in related USA Patents 9,174,284
and 7,200,940 also to MacKelvie). When the tool is forced downwards the
blade's
teeth engage the surface whereafter the blades are stroked a short distance
such that
the teeth plow stop-grooves displacing material upwards and towards the end of
each groove having a barbed shape. A single enlarged barb 3 is shown in Fig 6
embedded in media 5.
In one embodiment, barbs 3 are shown formed in concentric rings and in a
second embodiment, Fig 4, barbs 3 are shown formed in rows. Both embodiments
could be used together, the goal being to maximize the density of the barbs to
thereby provide maximum embedment strength into media 5.
Media 5 begins as a homogenous mixture of suitable compounds such
as silica, alumina, titanium-aluminide, ceramics, carbides, glass- metal- and
other
fibres, with other heat resistant minerals as required. The mix should be non-
abrasive, that is its mineral constituents having a generally smooth or
rounded
form, such as desert sand, as opposed to having angular sharpness such as when
hard minerals are freshly fractured. Abrasiveness would cause unwanted wearing
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of the brake pads. Also thoroughly mixed into media 5 is a heat-curable
binding
resins, such as phenolics and epoxies that cure hard and resist high heat, in
both
powder and liquid form. A one or more discs of glass fibre 9 shown in Fig 9
may
also be included with the media 5 for toughness and strength.
The media is compressed onto the rotor core 20, one barbed face at a time or
onto both simultaneously. This is carried out in a cylindrical heated mould
with
heated piston. A layer of media 5, with or without mesh 9, is placed in the
bottom
of the mould and rotor core 20 laid on top followed by a second layer of media
5. A
piston descends onto the three layer sandwich with great force (some 350
kilograms per square centimetre) to compress media 5 onto the barbs of rotor
core
10. The mould and piston can also heat the sandwich to the appropriate cure
temperature to form hard faces on the softer rotor core to thereby create the
desired
composite brake rotor.
Although the invention has been shown and described with respect to
detailed embodiments thereof, it should be understood by those skilled in the
art
that various changes in form and detail thereof may be made without departing
from the spirit and the scope of the claimed invention.
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