CA2999300A1 - Composite brake rotor - Google Patents

Abstract

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.

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 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;

2 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

3 riveted in place into the second countersink. This riveting together of discs 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

4 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.

Claims

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.