GB2562162A

GB2562162A - Brake disc

Info

Publication number: GB2562162A
Application number: GB1804404.0A
Authority: GB
Inventors: Hadley Ian
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2017-03-23
Filing date: 2018-03-20
Publication date: 2018-11-07
Also published as: GB201804404D0; GB201704596D0

Abstract

A vented brake disc for a vehicle, the brake disc comprising two cheeks spaced to form an air gap, wherein the centres of the cheeks are aligned along a central axis, and a plurality of sets of pillars 60, each set comprising an equal number of pillars that are disposed in the air gap and extend orthogonally between opposing faces of the cheeks. The pillars in each set are equally spaced around the circumference of a respective circle of a plurality of concentric circles of increasing diameter whose respective centres are positioned on the central axis. Alternate sets of pillars are aligned along alternate radii K1, K2, K3, K4 of a plurality of equi-angularly spaced radii extending outwardly from the central axis. The outermost concentric circles pillars 92 have a first dimension and the pillars of the remaining inner sets 94 have a second dimension that is less than the first dimension, wherein these dimensions are pillar diameter. In a further embodiment, pillar spacing between the outer surfaces of the nearest pillars from adjacent sets is equal for all pillars.

Description

(54) Title of the Invention: Brake disc

Abstract Title: Vented brake disc with concentric sets of pillars (57) A vented brake disc for a vehicle, the brake disc comprising two cheeks spaced to form an air gap, wherein the centres of the cheeks are aligned along a central axis, and a plurality of sets of pillars 60, each set comprising an equal number of pillars that are disposed in the air gap and extend orthogonally between opposing faces of the cheeks. The pillars in each set are equally spaced around the circumference of a respective circle of a plurality of concentric circles of increasing diameter whose respective centres are positioned on the central axis. Alternate sets of pillars are aligned along alternate radii K1, K2, K3, K4 of a plurality of equi-angularly spaced radii extending outwardly from the central axis. The outermost concentric circle’s pillars 92 have a first dimension and the pillars of the remaining inner sets 94 have a second dimension that is less than the first dimension, wherein these dimensions are pillar diameter. In a further embodiment, pillar spacing between the outer surfaces of the nearest pillars from adjacent sets is equal for all pillars.

Figure 4

BRAKE DISC

TECHNICAL FIELD

The present disclosure relates to a vented brake disc. Aspects of the invention relate to a brake disc, a brake assembly incorporating the brake disc and to a vehicle incorporating the brake assembly.

BACKGROUND

Disc brakes are increasingly replacing drum brakes in vehicles, especially at the front axle where the highest braking forces are needed. When compared with drum brakes, disc brakes benefit from an increased braking capability, improved cooling and a lower susceptibility to warping or ‘brake fade’ when subjected to high temperatures.

In order to further improve the performance of disc brakes, manufacturers have moved from solid disc brakes to vented disc brakes that incorporate an air gap between two plates or ‘cheeks’ of the brake disc. The air gap creates a greater surface area of vented disc brakes which generates a greater cooling effect. The cooling of the brake is further enhanced by air flowing through the brake disc air gap and across the ‘internal’ faces of the disc. The cheeks of the disc are connected by vanes or pillars and the design of these influence the air flow through the disc and the cooling efficiency of the disc. Curved vanes that are swept in the direction of disc rotation are used in some high end vehicles as they are particularly efficient at cooling.

However, curved vanes introduce a handedness to the brake disc. This doubles the part count and can mean additional tooling is required and additional part identification. This increases complexity, part cost and care must be taken during assembly of the vehicle, and during manufacture and service.

The present invention has been devised to mitigate or overcome at least some of the above-mentioned problems.

SUMMARY OF THE INVENTION

According to an aspect of the present invention there is provided a vented brake disc for use in a vehicle, the brake disc comprising: two cheeks spaced to form an air gap therebetween, wherein the centres of the cheeks are aligned along a central axis; and a plurality of sets of pillars, each set comprising an equal number of pillars that are disposed in the air gap and extend orthogonally between opposing faces of the cheeks. The plurality of sets of pillars comprise all pillars extending between opposing faces of the cheeks. The pillars in each set are equally spaced around the circumference of a respective circle of a plurality of concentric circles of increasing diameter whose respective centres are positioned on the central axis. Alternate sets of pillars are aligned along alternate radii of a plurality of equi-angularly spaced radii extending outwardly from the central axis. The pillars of the set positioned on the outermost concentric circle, having the largest diameter, have a first dimension and the pillars of the remaining, inner sets have a second dimension that is less than the first dimension. The first dimension is a first diameter. The second dimension is a second diameter.

In other words, the plurality of sets of pillars defined above represent all pillars in the brake disc which extend between opposing faces of the cheeks, and all pillars have a circular cross-section, from which a diameter may be measured. The diameters define two further categories of pillars: an outer category, having a first, large diameter and consisting of only the outermost set of pillars; and an inner category consisting of all of the remaining pillars on the brake disc, all of which have the same, second, smaller diameter.

Advantageously, this arrangement of pillars within a brake disc enhances the cooling effect of the brake disc by increasing the surface area across which cooling air is able to flow. In addition, cooling channels are created by the arrangement that mimic the effect of curved vaned brake discs. Furthermore, the brake disc is non-handed, ensuring that the brake disc can be mounted on either side of the vehicle without the requirement of specific tailoring. This reduces manufacturing costs as well as the likelihood of mounting the disc wrongly.

The first and second diameters may be measured at the centre point along the axial length of the respective pillars.

In one example, the first diameter may be less than or equal to 10mm. The first diameter may, for example, be less than 8.5mm and may, for example, be greater than 7mm.

In one example, the second diameter may be less than or equal to 8mm. The second diameter may, for example, be less than or equal to 6mm. In some applications, these diameter measurements significantly improve the performance of the brake disc.

The vented brake disc may comprise a plurality of pillar pairs, each comprising a primary pillar in one set and the nearest pillar to that primary pillar in an adjacent set. A pillar pair spacing between outer surfaces of the pillars in all pillar pairs may be equal. By specifying this pillar pair spacing, the pillars can be optimally arranged relative to one another and this enables as many pillars as possible to be incorporated into the brake disc. A higher number of pillars increases the surface area that is exposed and leads to a maximized cooling effect.

The pillar pair spacing may be measured between the centre points along the axial length of each pillar in the pillar pair.

In the first set of pillars having pillars arranged on the concentric circle having the smallest diameter, the distance between the outer surfaces of any two adjacent pillars may be equal to or greater than the pillar pair spacing.

In one example, the pillar pair spacing may be less than or equal to 10mm. The pillar pair spacing may, for example, be less than or equal to 8mm. In some applications, these pillar spacings significantly improve the cooling effect of the brake disc by increasing the exposed surface area without compromising the air flow within the air gap.

The vented brake disc may comprise at least six sets of pillars. In some embodiments, the number of sets of pillars is the maximum number of pillars that are able to be incorporated in the brake disc for a given internal surface area of the cheeks. For example, smaller brake discs may only incorporate five or fewer sets of pillars, while bigger brake discs may incorporate seven, eight, nine or more sets of pillars. The number of sets of pillars may also be influenced by a minimum allowable spacing defined by the manufacturing technique. If the pillars can be positioned closer to one another, then more sets will be incorporated into the brake disc.

The number of pillars in each set may be greater than or equal to 40 and may be fewer than or equal to 55. The number of pillars is dependent upon the size of the brake disc and the angle between the radii.

According to another aspect of the present invention, there is provided a vented brake disc for use in a vehicle, the brake disc comprising: two cheeks spaced to form an air gap therebetween, wherein the centres of the cheeks are aligned along a central axis; and a plurality of sets of pillars, each set comprising of an equal number of pillars that are disposed in the air gap and extend orthogonally between opposing faces of the cheeks; the plurality of sets of pillars comprising all pillars extending between opposing faces of the cheeks; wherein the pillars in each set are equally spaced around the circumference of a respective circle of a plurality of concentric circles of increasing diameter whose respective centres are positioned on the central axis; wherein alternate sets of pillars are aligned along alternate radii of a plurality of equi-angularly spaced radii extending outwardly from the central axis; wherein the brake disc comprises a plurality of pillar pairs each comprising a primary pillar in one set and the nearest pillar to that primary pillar in an adjacent set; and wherein a pillar pair spacing between outer surfaces of the pillars in all pillar pairs is equal.

By specifying this pillar pair spacing, the pillars can be optimally arranged relative to one another to enable as many pillars as possible to be incorporated into the brake disc. A higher number of pillars increases the surface area that is exposed and leads to a maximized cooling effect. In addition, this arrangement also allows cooling channels to be created that mimic the effect of curved vaned brake discs and retains a non-handedness within the brake disc, ensuring that the brake disc can be mounted on either side of the vehicle without the requirement of specific tailoring.

The pillar pair spacing may be less than or equal to 10mm. The pillar pair spacing may be less than or equal to 8mm.

In one example, the vented brake disc may comprise at least six sets of pillars. The number of pillars in each set may be greater than or equal to 40 and may be fewer than or equal to 55.

According to another aspect of the present invention, there is provided a brake assembly for a vehicle, the brake assembly comprising a vented brake disc as described above and a brake calliper.

According to another aspect of the present invention, there is provided a vehicle comprising at least one brake assembly as described above.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective of a vehicle incorporating a vented brake disc according to an embodiment of the invention;

Figure 2 is a cross-sectional diagram of a partial suspension corner assembly of the vehicle of Figure 1 according to an embodiment of the invention;

Figure 3 is a perspective view of a brake disc forming part of the partial suspension corner assembly of Figure 2;

Figure 4 is a perspective view of a pillar forming part of the brake disc of Figure 3;

Figure 5 is a plan view of a cheek of the brake disc forming part of the brake disc of Figure 3; and

Figure 6 is the plan view of Figure 5 with concentric circles overlaid indicating sets of pillars.

DETAILED DESCRIPTION

Figure 1 shows a perspective view of a vehicle 10 that incorporates a brake disc (not shown in Figure 1) according to an embodiment of the invention. The vehicle 10 includes a pair of front suspension corner assemblies 12 (left and right) and a pair of rear suspension corner assemblies 14 (left and right), only the right hand ones of which are shown here.

Each suspension corner assembly 12, 14 includes a wheel assembly comprising a wheel 16 onto which a tyre 18 is mounted, the wheel 16 being connected to a rotatable axle (not shown in Figure 1) and housed within a respective wheel arch 20 in a conventional manner.

Figure 2, which is not to scale and has been slightly simplified to improve the clarity of the figure, shows a cross sectional representation of a wheel assembly of the vehicle 10, referred to generally as 22. Considering both Figures 1 and 2, the wheel assembly 22, which is housed within an associated wheel arch 20 of the vehicle 10, includes a wheel 16, a tyre 18 and a brake assembly 24, where the wheel assembly 22 is rotatable about a front axle 26 of the vehicle 10. Although not shown here, the wheel assembly 22 forms part of the front or rear suspension corner assembly 12, 14 and so is mounted to and interacts with other components related to the suspension of the vehicle 10. These components are known to the skilled person and so will not be discussed in detail here.

The wheel 16 includes a circular, central portion 28 that is connected to the wheel hub 30 via a mount 32 of the disc brake 34 by a plurality of fixings 36 extending through both the central portion 28 of the wheel 16 and the wheel hub 30. The wheel hub 30 is fixed to the front rotatable axle 26.

The axle 26 is arranged so that it lies along axis of rotation R of the wheel assembly 22.

The wheel 16 further comprises a plurality of spokes 38, extending radially outwardly from the central portion 28 of the wheel 16, and an annular rim 40 that encircles the spokes 38 and central portion 28. The spokes 38 connect to the central portion 28 of the wheel 16 at one end 42 and extend radially outwardly from the central portion 38 to connect to an inner face 44 of the rim 40 at their opposite, distal ends 46.

The rim 40 incorporates an outwardly facing recess 48 for receiving a portion of a tyre 18 to be mounted on the wheel 16. The rim 40 also surrounds a cavity 52 in which other components of the wheel assembly 22 are housed, such as the hub 30 and the brake assembly 24.

The brake disc 34 comprises a pair of annular cheeks 54, 56 spaced apart from one another to form an air gap 58 between the cheeks 54, 56 so that, in use, air flows over a greater surface area of the disc 34 as would ordinarily flow over a solid brake disc that did not have two cheeks. The cheeks 54, 56 are spaced apart, and the air gap 58 maintained, using an internal structure having a plurality of pillars 60. The internal structure defines an air flow path for allowing air flow radially outwardly through the brake disc 34, as will be discussed later.

The brake disc 34 also includes a mount 32 that is connected to one of the cheeks 56. The mount 32 incorporates a plurality of fixing holes (not shown) through which the wheel fixings 36 may be passed. The wheel hub 30 is configured to sandwich the mount 32 between it and the central portion 28 of the wheel 16. The wheel fixings 36 fix the hub 30 and brake disc 34 to the wheel 16, so that when the hub 30 rotates, both the wheel 16 and the brake disc 34 rotate too.

Wheel hubs are conventionally known, and so will not be discussed further. Other configurations of the wheel hub and axle relative to the brake disc, as well as configurations of other known components, are equally compatible with the present invention.

Each front wheel assembly additionally comprises a calliper 62. The brake assembly is required to enable slowing or stopping of the vehicle 10, and this is implemented by using the calliper 62 to apply a force to the brake disc, creating friction to reduce the rotational speed of each wheel 16 and tyre 18. However, applying friction to the brake disc converts the rotational kinetic energy to heat energy that must be efficiently dissipated from the brake disc to reduce the likelihood of adverse effects due to overheating. The brake disc of the invention, improves the cooling efficiency of the system, thereby allowing for a higher level of performance by the brake system. To implement a braking action on the rotating brake disc 34 and wheel 16, the calliper 62 exerts an inward force on the outer faces of the cheeks 54, 56.

As illustrated by Figure 3, each cheek 54, 56 of the brake disc 34 is annular in shape, and both cheeks 54, 56 are arranged to surround a main, or central, axis R of the wheel assembly 22, such that the centres of the cheeks 54, 56 are aligned with the main axis R, the plane of each cheek 54, 56 being perpendicular to the main axis. The main axis passes directly through the central point, and point of rotational symmetry, of the annular cheeks 54, 56. The axis R is the axis about which the axle 26 and the wheel hub 30 rotate, as shown in Figure 2.

Both cheeks 54, 56 are of identical diameter and are aligned so that the air gap 58 between the cheeks 54, 56 is constant across the full radial extent.

The pillars 60 disposed within the air gap 58 will now be described. The shape of the individual pillars 60 will be considered with reference to Figure 4, while the arrangement of pillars 60 on the brake disc 34 will be discussed with reference to Figures 5 and 6.

As illustrated in Figure 4, each individual pillar 60 is cylindrically shaped and flares at either end to provide a draft angle with the surface 64, 66 of each cheek 54, 56 between which the pillars 60 extend orthogonally. The diameter of each pillar 60 is thus smallest at the centre point along its axial length. Each pillar 60 extends orthogonally between the facing cheeks 54, 56 of the brake disc 34 and across the air gap 58 between the cheeks 54, 56. As the air gap 58 formed between the cheeks 54, 56 of the brake disc 34 is constant, and each pillar 60 extends from the inner surface 64 of one cheek 54 to the inner surface 66 of the opposite cheek 56, the length of each pillar 60 is identical.

Incorporating a draft angle ensures that the disc core, which is used to form the air gap 58 and pillars 60 when manufacturing the brake disc 34, can be removed safely from the brake disc 34 without damage.

Turning now to Figures 5 and 6, which both illustrate the same arrangement of pillars 60 relative to one cheek 54 of the brake disc 34, it can be seen that the pillars 60 are arranged so as to form a non-handed, swept configuration. This arrangement advantageously improves air flow and the cooling efficiency of the brake disc 34 once fully assembled. Additionally, the arrangement is devised so that each brake disc 34 is non-handed, and can therefore be fitted to either side of a vehicle 10. This significantly reduces manufacturing costs and time, and reduces the risk of errors in fitting.

As shown in Figures 5 and 6, the pillars 60 are arranged such that their longitudinal axes are aligned in parallel with the main axis of rotation R, and positioned in a regular pattern on the circumferences of a plurality of concentric circles which lie in the plane of the cheeks 54, 56.

In more detail, a first set 68 of pillars 60, comprising a first plurality of pillars 60, is arranged on the circumference of a first concentric circle 70 centred on the main axis of rotation R. The pillars 60 in the first set 68 are spaced equally around the circumference of the first concentric circle 70. The pillars 60 of the first set 68 are arranged such that the distance of the centre of each pillar 60 of the first set 68 from the main axis of the brake disc 34 is equal to a first radius which shall be referred to as the radius of the first concentric circle 70.

A second set 72 of pillars 60, comprising the same number of pillars 60 as make up the first set 68 of pillars 60, is arranged on the circumference of a second concentric circle 74 in the same manner as the first set 68, with the second concentric circle 74 being centred on the axis of rotation R. The second concentric circle 74 has a larger diameter than the first concentric circle 70, and thus lies radially outward of the first concentric circle 70 relative to the axis of rotation R. The brake disc 34 may comprise any number of pillar sets, and thus any number of concentric circles on the circumferences of which the pillars are arranged. Each concentric circle has a different diameter, with the diameter of additional concentric circle being greater than the diameter of the innermost, first concentric circle 70. The arrangement of Figures 5 and 6 has six sets 68, 72, 76, 78, 80, 82 of pillars 60 arranged on respective concentric circles 70, 74, 84, 86, 88, 90 of increasing diameter. The six sets of pillars represent all pillars of the brake disc.

In general, all pillar sets have the same number of pillars 60 and all of the pillars in each individual set have identical dimensions, and in particular have identical diameters when measured at the centre point along the axial length of the respective pillars. Additionally, with the exception of the outermost set of pillars, the dimensions, and hence diameters, of pillars in all sets of pillars are identical. Put another way, the pillars of the radially outermost set of pillars (i.e. the set whose pillars are furthest from the main axis) have, for example, a first diameter, and the pillars in all the other sets have, for example, a second diameter. The first diameter is greater than the second diameter.

To demonstrate this, a brake disc 34 such as that shown in Figures 5 and 6 has six sets 68, 72, 76, 78, 80, 82 of pillars 60. The first set 68 of pillars 60 contains all the pillars 60 that are closest to the main axis R of the brake disc 34. The sixth set 82 contains the pillars 60 that are radially furthest from the main axis R. In this situation, the sixth, outermost set 82 comprises pillars 92 having a first diameter, while the first to fifth sets 68, 72, 76, 78, 80 comprise pillars 94 having a second diameter that is less than the first diameter.

In another example, in a brake disc having seven sets of pillars, only the seventh set would have a first diameter, while the first to sixth sets would have a second, smaller diameter. In another example, in a brake disc having eight sets of pillars, only the eighth set would have a first diameter, while the first to seventh sets would have a second, smaller diameter, and so on for an increasing number of pillar sets.

The number of sets of pillars and the number of pillars within a set are parameters defined by the available surface area of the brake disc, the pillar diameters and the minimum spacing between pillars.

When considering the arrangement that allows for a swept, non-handed configuration, it should be remembered that the pillars of each set are spaced equally around their respective concentric circles. As each set contains the same number of pillars and the pillars in respective sets are arranged on concentric circles having different diameters, the spacing between adjacent pillars in a set is unique to that set and is proportional to the diameter of the corresponding circle on which the pillars lie.

The sets of pillars are arranged so that there is an offset in the pillars of adjacent sets, and so that pillars of alternate sets are aligned. So, if a plurality of equi-angularly spaced radii are considered that extend radially outwardly from the main axis of the brake and the number of radii in the plurality is double the number of pillars in a single set, then odd sets of pillars are aligned so that the first radius passes through a first pillar of each of the odd sets, and the third radius passes through a second pillar of each of the odd sets, and so on. In this embodiment, “equi-angularly spaced” means that the angle between each pair of adjacent radii is the same or substantially equal.

Even sets of pillars are aligned so that the second radius passes through a first pillar of each of the even sets, the fourth radius passes through a second pillar of each of the even sets and so on. In general, even radii pass through one pillar of each of the even sets only and odd radii pass through one pillar of each of the odd sets only. Hence, the angular separation between adjacent pillars in a set is the same for all sets, and adjacent sets are angularly offset by half the angular separation of the pillars.

In the arrangement of pillars shown in Figure 5 where there are six sets 68, 72, 76, 78, 80, 82 of pillars 60, the first pillar of each of the first, third and fifth sets 68, 76, 80 lie on the first radius K1, at increasing radial distances from the main axis R. The first pillar of each of the second, fourth and sixth sets 72, 78, 82 lie on the second radius K2 at increasing radial distances from the main axis R. The second pillar of each of the first, third and fifth sets 68, 76, 80 and of the second, fourth and sixth sets 72, 78, 82 lie on the radii K3 and K4 respectively, and so on. This pattern is repeated for the entire circumference of the brake disc 34.

To further define the relationship of the pillars 60 on the cheek 54 according to the invention, a plurality of pillar pairs are defined. Generally, each pillar pair comprises a first, primary pillar in one set of pillars and the nearest pillar to that primary pillar in an adjacent set. The term ‘nearest pillar’ as used herein relates to the pillar that is the shortest distance from the primary pillar. Due to the equal spacing of pillars within the sets, it is expected that for each primary pillar, there will be four nearest pillars except where the primary pillar lies in the innermost or outermost set of pillars, where there will only be two nearest pillars. So, each pillar of the disc brake can be considered to be part of at least two pillar pairs. The pillars are arranged within the pairs so that the spacing between them is the same as a predetermined pillar pair spacing. This assumes that this spacing is measured from the outer surface of one pillar to the outer surface of the other pillar, and from the point along the axial length of the pillar at which the diameter of each pillar is smallest. The pillar pair spacing is the same for all pillar pairs.

It is also the case that the pillar pair spacing is the minimum spacing between any two pillars. Again, it is assumed that this spacing is measured from the outer surface of one pillar to the outer surface of the other pillar, and from the point along the axial length of the pillar at which the diameter of each pillar is smallest.

To provide an example using the arrangement show in Figures 5 and 6, the distance from pillar P1 (labelled only on Figure 6 for clarity), which is part of both the first pillar set 68 and lies on the radius K1, to pillar P2, which is part of both the second pillar set 72 and lies on the radius K2 is equal to the pillar pair spacing. This distance is the same as the distance from the pillar P2 to the pillar P3, which is part of the third pillar set 76 and lies on the third radius K3, or from pillar P2 to pillar P4, which is part of the first pillar set 68 and lies on the third radius K3, for example. Pillars P1, P3, P4 and P5, which is part of the third pillar set 76 and lies on radius K1, are the nearest pillars to pillar P2.

This spacing ensures that the distance between the outer surface of a pillar in one pillar set and the outer surfaces of the nearest two pillars in an adjacent pillar set is the same for all the pillars.

In some embodiments, this pillar pair spacing will also be equal to the spacing between outer surfaces of adjacent pillars of the innermost pillar set. In other embodiments, the spacing between outer surfaces of adjacent pillars of the innermost pillar set will be greater than the pillar pair spacing. It is envisaged that this distance will be less than 10 mm, more typically less than 9mm and still more typically around 8mm.

By arranging the pillars as described above, a swept configuration of the pillars in both rotational directions of the brake disc is formed. This ensures that directed air flow across the disc is enabled irrespective of the direction of rotation of the disc. When the disc rotates, the air flows through swept ‘cooling channels’ formed by the flow of air relative to the rotation of the disc. The cooling channels are formed by between the pillars of the arrangement described above and as shown in Figure 5. The cooling channels that are formed curve away from the centre of the disc. Thus, when a brake disc formed of two opposing cheeks, arranged as shown in Figures 5 and 6, rotates in a clockwise sense, the air flows through cooling channels as indicated by arrow A1.

When the disc shown in Figures 5 and 6 rotates in an anti-clockwise sense, the cooling channels curve in the opposite direction, as indicated by arrow A2.

The use of pillars in this manner means that one design of brake disc can be produced and used on both sides of a vehicle. The pattern of pillars reduces the amount of stagnant air within the air gap between the cheeks, while improving the transfer of heat from the disc to the air flowing through the air gap.

Incorporating an outer set of pillars having a larger diameter than those closer to the main axis ensures a greater volume of air comes into contact with the pillars on the outer ring, and therefore a high transfer of heat energy from the pillars to the air. It also reduces the likelihood of stagnant air at the outer edge of the disc by disrupting the flow of the air in this region.

In some embodiments, the pillars of the outermost set are expected to have diameters of less than 10mm, while the diameters of the pillars of the inner sets may be less than 7mm. In some embodiments, the pillars of the outermost set may be greater than 7mm and less than 8.5mm. For example, in one embodiment, the pillars of the outermost set have diameters of 7.8mm (measured at the centre point along the axial length of the pillar), while the pillars of the remaining, inner sets have diameters of 6mm. In a brake disc having six sets of pillars, whose outer set comprises pillars having a diameter of 7.8mm and whose inner sets comprise pillars having a diameter of 6mm, it is envisaged that each set of pillars would comprise greater than 40 and fewer than 60 pillars, depending upon the size of the disc.

It will be appreciated that any size of pillars, any number of sets, and any number of pillars per set are possible providing an adequate air flow passage is made available to achieve the desired cooling flow between the cheeks. The numbers here depend upon the size of the disc and the manufacturing tolerances available.

In some embodiments, the shortest distance between pillars is less than or equal to

8mm. In some embodiments, the outer pillar is positioned at least 5mm from the edge of the outer edge of the brake disc.

It is also envisaged that the air gap may have a width of greater than 7mm. It is possible for an air gap to have a width in the range from 7mm to 20mm, and the air gap may have a width greater than these measurements depending upon the diameter of the cheeks. The thickness of the cheeks may be greater than 7mm, and may fall in the range of 8mm to 13mm, depending upon acceptable forces and stresses experienced by and exerted by the disc.

Many modifications may be made to the above examples without departing from the scope of the present invention as defined in the accompanying claims.

Claims

1. A vented brake disc for use in a vehicle, the brake disc comprising:

two cheeks spaced to form an air gap therebetween, wherein the centres of the cheeks are aligned along a central axis; and a plurality of sets of pillars, each set comprising an equal number of pillars that are disposed in the air gap and extend orthogonally between opposing faces of the cheeks, the plurality of sets of pillars comprising all pillars extending between opposing faces of the cheeks;

wherein the pillars in each set are equally spaced around the circumference of a respective circle of a plurality of concentric circles of increasing diameter whose respective centres are positioned on the central axis;

wherein alternate sets of pillars are aligned along alternate radii of a plurality of equi-angularly spaced radii extending outwardly from the central axis;

wherein the pillars of the set positioned on the outermost concentric circle, having the largest diameter, have a first dimension and the pillars of the remaining, inner sets have a second dimension that is less than the first dimension; and wherein the first dimension is a first diameter, and wherein the second dimension is a second diameter.

2. The vented brake disc of Claim 1, wherein the first and second diameters are measured at the centre point along the axial length of the respective pillars.

3. The vented brake disc of Claim 1 or Claim 2, wherein the first diameter is less than or equal to 10mm.

4. The vented brake disc of any preceding claim, wherein the first diameter is less than 8.5mm and greater than 7mm.

5. The vented brake disc of any preceding claim, wherein the second diameter is less than or equal to 8mm.

6. The vented brake disc of any of preceding claim, wherein the second diameter is less than or equal to 6mm.

7. The vented brake disc of any preceding claim, comprising:

a plurality of pillar pairs, each comprising a primary pillar in one set and the nearest pillar to that primary pillar in an adjacent set; and wherein a pillar pair spacing between outer surfaces of the pillars in all pillar pairs is equal.

8. The vented brake disc of Claim 7, wherein the pillar pair spacing is measured between the centre points along the axial length of each pillar in the pillar pair.

9. The vented brake disc of Claim 7 or Claim 8, wherein, in the first set of pillars having pillars arranged on the concentric circle having the smallest diameter, the distance between the outer surfaces of any two adjacent pillars is equal to or greater than the pillar pair spacing.

10. The vented brake disc of any of Claims 7 to 9, wherein the pillar pair spacing is less than or equal to 10mm.

11. The vented brake disc of any of Claims 7 to 10, wherein the pillar pair spacing is less than or equal to 8mm.

12. The vented brake disc of any preceding claim, comprising at least six sets of pillars.

13. The vented brake disc of any preceding claim, wherein the number of pillars in each set is greater than or equal to 40 and fewer than or equal to 55.

14. A vented brake disc for use in a vehicle, the brake disc comprising:

two cheeks spaced to form an air gap therebetween, wherein the centres of the cheeks are aligned along a central axis; and a plurality of sets of pillars, each set comprising of an equal number of pillars that are disposed in the air gap and extend orthogonally between opposing faces of the cheeks, the plurality of sets of pillars comprising all pillars extending between opposing faces of the cheeks;

5 wherein the pillars in each set are equally spaced around the circumference of a respective circle of a plurality of concentric circles of increasing diameter whose respective centres are positioned on the central axis;

wherein alternate sets of pillars are aligned along alternate radii of a

10 plurality of equi-angularly spaced radii extending outwardly from the central axis;

wherein the brake disc comprises a plurality of pillar pairs each comprising a primary pillar in one set and the nearest pillar to that primary pillar in an adjacent set; and

15 wherein a pillar pair spacing between outer surfaces of the pillars in all pillar pairs is equal.

15. A brake assembly for a vehicle, the brake assembly comprising the vented brake disc of any preceding claim and a brake calliper.

16. A vehicle comprising at least one brake assembly according to claim 15.

Intellectual

Property

Office

Application No: GB1804404.0 Examiner: Mr Samuel Taylor