The present invention relates to a brake disc assembly, to a method for the manufacture, process for the assembly and to the use of the assembly or a component thereof, in particular to a brake disc assembly providing for moving adjustment of component parts, in particular in response to thermal stresses, to the process for the assembly in the form of component parts and to the use thereof, more particularly to a high performance ventilated brake disc assembly.

Disc brakes are conventionally employed in most forms of wheel-driven engines or vehicle, in particular motor vehicles, trains, elevators, motor bikes and the like. Design modifications are extensive, however characteristically all comprise one or more friction pads mounted in non-rotating manner and adapted to contact an annular friction disc or ring having one or more friction surfaces supported or comprised on a mounting hub or carrier adapted to be rigidly connected with the (drive) wheel of a vehicle, for example the wheel- hub, in suitable manner. Closing the friction pad(s) by calliper action onto the rotating friction surface(s) causes braking.

Disc brakes and their mountings must be designed to meet a number of requirements, in particular a good heat resistance to friction braking and compatibility of components to allow for differences in thermal expansion without distortion or deviation of the friction surfaces which would result in inferior contact with the carrier and accordingly inadequate braking, oil and solvent resistance, high mechanical integrity, economically efficient manufacture of a disposable item, i.e. the friction surface itself, and design of

suitable attachment means for the disposable item. Attempts to address these requirements have resulted in the design of "floating" friction discs, as a departure from previously riveted discs, whereby the disc-mounting attachment allows for moving adjustment or "float" of component parts to accommodate differences in thermal expansion, however these designs have invariably utilised fixing or retention means which can disengage if incorrectly assembled, employed beyond a normal lifetime or subject to the shock of vehicle impact. Alternatively or additionally, designs have employed ventilation means, typically provided as air passages in radially outward direction along the disc and/or mounting face(s), whereby rapid air flow is created on rotation of the assembly, resembling a rotor-type effect. Nevertheless this is insufficient to overcome extreme heat accumulation incurred with high performance and/or heavily laden vehicles. More recently designs have employed carbon fibre components. However such discs are prohibitively expensive and their use in typically limited to high performance and racing applications. Moreover the frictional braking force, is low at low temperatures and only becomes reliable and effective at higher disc temperatures.

Accordingly there is a need for a disc brake which is adapted to meet the hereinbefore mentioned requirements and may be manufactured simply and efficiently for economical use in high cost and low cost applications.

We have now surprisingly found that a simple and effective means may be employed for the attachment with secure retention of a brake disc and carrier mounting, which means is adapted for moving adjustment of component parts, which may be manufactured and assembled to a high degree of safety and reliability, and is characterised by outstanding performance whilst being

essentially of simple construction.

In its broadest aspect there is provided according to the present invention a brake disc assembly comprising an annular disc and a carrier mounting therefor, adapted to associate at respective inner annular rim and outer circumferential rim, and annular attachment means therefor, wherein each of the disc and carrier is adapted to expand by means of incremental increase of the respective diameters thereof and wherein the attachment and association means are adapted to provide for moving adjustment of component parts to accommodate expansion thereof.

The annular disc and carrier mounting may expand or contract in response to thermal increase or decrease thereof. A thermal expansion of a closed ring or disc will typically follow the lowest constraint, whereby in the absence of circumferentially constraining forces, the natural expansion is by incremental diameter increase or decrease as hereinbefore defined.

Preferably the attachment means comprises a high strength material which may be of high or low, preferably low thermal expansion. Preferably the attachment means comprises an open annular ring, i.e. having a passage between the inner and outer annular rim thereof such as a radially or otherwise aligned break, whereby it is adapted to deform by radially outward or inward directed force, which is of advantage in the location and assembly thereof.

Conventional discs and carriers comprise regularly spaced planar apertures or recesses which are adapted for coincidence on placing the disc and carrier in coaxial alignment for assembly.

Preferably a disc and carrier as hereinbefore defined resemble such discs and carrier known in the art, whereby a disc is an annular ring having planar projections on the inner annular rim thereof adapted to engage opposing planar recesses on the outer circumferential rim of the carrier, thereby creating in combination a continuous profile at the carrier outer rim. Suitably a disc and carrier will each comprise three or more projections and recesses, thereby creating three or more association points, preferably the number thereof is adapted to the size and mechanical requirement of the disc, more preferably is in the range 6-30, most preferably 8-15 recesses.

In a preferred embodiment of the invention, planar projections and recesses as hereinbefore defined are substantially radially projecting and receding, and are adapted for radially unconstrained association, for example on subjecting the disc-carrier assembly to rotation about a common access. Preferably means are provided for the closure of each recess at each planar face thereof, adapted to abut each planar face of a mating projection received therein. Preferably attachment means comprises a single annular ring adapted to seat against each recess at one planar face thereof, whereby it provides a removable closure allowing for manual assembly and dessembly, and each recess comprises a substantially permanent, integral or otherwise, closure at the opposite planar face thereof.

The attachment means may be adapted to seat against the recess faces as hereinbefore defined by any suitable means allowing for moving adjustment thereof. Preferably the carrier mounting comprises at one face thereof a return flange projection extending in axial and in radial direction to a face thereof, adapted to receive and partially surround the annular attachment means. More

preferably the return flange extends in axial direction at the circumferential rim of the carrier mounting and in radially inward direction, providing an annular aperture, adapted for radially outward and axial-directed constrained seating of the annular attachment ring. The flange projection is suitably comprised of a plurality of return flanges, arranged between mating recesses, thereby allowing for receipt of mating projections of an annular disc, as hereinbefore defined, between each flange projection.

Preferably the opposite face of the carrier mounting, remote from the return flanges, is substantially continuous or solid, i.e. the mating recesses at its circumference are provided at one face thereof corresponding to the face adapted to seat the attachment means, and do not extend through to the opposite face which thereby provides the permanent closure adapted to abut mating projections received in each recess.

It will be appreciated that in a particular advantage of the invention, the assembly exploits the configuration and the natural expansion of the component parts to assist in floating retention thereof. In the preferred embodiment, mating projections and recesses secure the disc and carrier against relative disengagement in circumferential or tangential direction and, together with coincidence of annular and circumferential rims of disc and carrier, secure the disc from radial inward (centripetal) and outward (centrifugal) disengagement.

In addition the closure at inner and outer faces of mating recesses and mating projections adapted to be received therein, secure against axially directed disengagement.

The carrier of the assembly of the invention suitably comprises any nature of return flange projection(s) such that the carrier face and return flange(s) are adapted for the secure retention of attachment means therebetween, suitably the flange projection is of any suitable geometry adapted to engage the hereinbefore defined attachment means, preferably is of dog-leg or concave configuration.

In a particular advantage of the preferred embodiment of the invention, the means of attaching the annular disc and carrier mounting enables provision of an annular disc having flat disc faces, i.e. not requiring laterally projecting bolts, buttons and the like, which allows excellent brake pressure dissipation into the carrier and uniform, hence reduced, wear.

Preferably the face of the carrier adapted for inward orientation towards the wheel on which it is to be mounted is substantially flat, and may diverge outwardly therefrom, such as at the circumferential carrier rim to provide for inward projection of the return flanges.

It will be appreciated that mechanical equivalents of the hereinbefore defined assembly may be employed in manner known in the art, for example a resiliently deformable annular ring is representative of any suitable annular spring and is functionally equivalent to any annular ring having alternative and additional means for attachment in similar manner.

In a further aspect of the invention there is provided a ventilated brake disc assembly comprising the assembly as hereinbefore defined wherein one or both of the disc and mounting comprise ventilation means adapted for cooling heat exchange contact with atmospheric air. Preferably ventilation means comprises

a plurality of substantially radially directed vanes at the outside face of the carrier, and/or a plurality of vents machined laterally at regular intervals through the disc, creating thereby a vented rotor. More preferably the vents in a vented disc or rotor correspond to the fan vanes machined in the carrier, allowing maximum air flow from the fan vanes through the rotor vents. It will be appreciated that the air flow is proportional to the angular speed of the assembly, and accordingly the cooling effect achieved.

It will be appreciated that any manner of known ventilation may be employed, for example the carrier disc may comprise a plurality of machined holes from one face to the other, serving for ventilation and simultaneous lightening of the device.

The ventilated assembly as hereinbefore defined may comprise a backing plate located in association with the outer face of the carrier, whereby carrier vanes are enclosed between the carrier and the backing plate. Suitably the backing plate comprises air inlet means enabling controlled intake, passage and cooling of the assembly. The backing plate is suitably mounted fixedly with relation to the wheel and is not adapted for rotation with the assembly of the invention. Preferably a backing plate comprises an air inlet adapted to be positioned in a high pressure area with relation to the wheel mounting, for example on a motor bike it will be located below the fork leg, maximising air intake. A suitable intake may comprise a scoop design creating a circumferentially directed inlet passage of which the inlet opening direction is coincident with intended direction of motion of a vehicle. The scoop inlet or aperture may be fitted with a small air filter to prevent stones and the like being drawn in and causing damage to the assembly. The backing plate preferably is distanced by a small

gap from the disc, preventing wearing or heat distortion, thereby maximising the passage of air through the disc rotor vents, rather than about the outside thereof.

The backing plate air inlet is suitably adapted to be positioned such that maximum air flow passes through the region of maximum heat accumulation of the disc, for example just after the calliper. The aperture size is suitably such as to prevent disturbance of steering control, preferably is smaller than the total vented area in the disc.

It will be appreciated that the advantages of the assembly as hereinbefore defined are numerous, and include additionally the provision of a light assembly providing a superior ratio of heat dissipation surface area to total dimensions, may comprise only three components thereby providing a simple assembly with minimum maintenance and failure, and provides flat face disc and small separation of carrier to calliper, providing excellent braking efficiency and minimum spillage of cooling air in the ventilated design.

Accordingly in a further aspect of the invention there is provided the use of an assembly as hereinbefore defined in the braking system of a vehicle, preferably of a high performance automotive or motorcycle, particularly for competition and racing. The device is advantageously adapted to be manually assembled by virtue of the self-engaging nature thereof.

In a further aspect of the invention there is provided a process for the assembly of an assembly as hereinbefore defined comprising locating a disc as hereinbefore defined in association with a carrier as hereinbefore defined by

bringing these laterally into mating association as hereinbefore defined, and introducing attachment means as hereinbefore defined thereby securing the disc in moving retention with the carrier. In a preferred aspect, the method for assembly comprises bringing mating projections and recesses as hereinbefore defined into association, whereby the projections abut against the carrier at its opposite face, and deforming an open annular ring, i.e. having a break as hereinbefore defined, by radial inward compression to pass this underneath the return flanges as hereinbefore defined and release compression allowing resilient expansion thereof to seat against the front face of the recesses as hereinbefore defined.

In a further aspect of the invention there is provided a kit of parts comprising one or more of a disc and carrier and optional backing plate as hereinbefore defined and a resiliently deformable attachment means as hereinbefore defined. Preferably a kit of parts comprises a plurality of each component part adapted for the assembly of one or more disc-brakes as hereinbefore defined.

Components of the assembly of the invention may be made of any suitable material adapted for the purpose, for example having a thermal resistance up to a temperature of the region of 700 C, being readily extrudable, mouldable or machineable, having a high oil and solvent resistance and preferably having a low co-efficient of thermal expansion or alternatively comprising components having the same or similar uniform co-efficient of thermal expansion throughout. Suitable materials include metals, alloys and polymers, preferably high performance alloys and metals. Preferably each component part of the assembly is constructed as a single integral component whereby failure of welds and joints is not envisaged.

In a further aspect of the invention there is provided a process for the manufacture of a device as hereinbefore defined comprising obtaining a material as hereinbefore defined and forming into components, comprising a disc and carrier and optional backing plate as hereinbefore defined and a component comprising resiliently deformable attachment means as hereinbefore defined having compatible dimensions and configuration as hereinbefore defined.

The disc and carrier as hereinbefore defined are suitably machined from solid, allowing the components to be void of casting stresses. Suitably the disc is machined from solid iron bars such as graphite iron bars preferably spheroidical (SG) or the like, providing the necessary mechanical integrity. Suitably the carrier is machined from aluminium alloy such as HE 30.

The attachment means comprising an annular ring as hereinbefore defined is suitably constructed from material strong enough to retain the disc in association with the carrier as hereinbefore defined, and capable of withstanding the operating temperatures generated in use. Preferably the annular ring comprises a laminar structure of a material selected from synthetic polymers, fibres, alloys, metals and the like, preferably selected from stainless steel and mixtures thereof with other components. The laminar ring is therefore advantageously light, strong and simple to produce, and provides the desired degree of resilient deformability.

A backing plate as hereinbefore defined is suitably comprised of a carbon fibre moulding for lightness and appearance, however maybe constructed of equivalent suitable materials as desired, such as aluminium or the like.

Further aspects of the invention will be apparent from the foregoing.

The invention is now illustrated in non limiting manner with reference to Figures 1-6 wherein.

Figure 1 is a cross section view from the inside face of an assembly of the invention.

Figures 2-6 are front elevations and corresponding end elevations of the component parts of an assembly of the invention.

Figure 1 illustrates carrier (1), disc (2), annular ring (3) and optional backing plate (4). The carrier (1) is suitably constructed of aluminium and recedes towards the rim thereof, and includes return flanges (5) along its circumferential rim. Carrier vanes (6) are indicated projecting outwardly from the outward face thereof. Disc (2) comprises vents (7). Annular ring (3) includes expanding break (9).

Detail A and B show a cross sectional view through the carrier (part) (1), disc (2) and ring (3) at lines A and B respectively. In detail B mating projection (10) and recess (1 1) are indicated.

In Figure 2 is shown carrier (1) and disc (2), with associated mating projections and recesses (10), (11). In this case sixty vents (7) are indicated. Mounting means (12) is shown, as standards.

In Figure 3 carrier (1) is shown, indicating vanes (6) and recesses (11) on the inside face thereof, not projecting through to the outside face. In end elevation the divergent configuration of the carrier is apparent, for both vented and non vented options.

In Figure 4 disc (2) is shown including vents (7) and mating projections (10). In cross section the vents and mating projection are apparent.

In Figure 5 the annular ring is shown (3) with expanding break (9).

In Figure 6 the backing plate (4) is shown with air inlet aperture (13) and scoop (14).