CN112771283A - Disk brake rotor and method for manufacturing same - Google Patents

Abstract

A disc brake rotor comprising opposed braking bands separated by an array of posts; the posts being integral with and extending between the opposite inner surfaces of the opposite brake bands; the rotor further includes a connector ring structure forming a one-piece casting with the opposing braking band; the connector ring structure projects radially outward and inward from the inner ring of the posts of the post array.

Description

Disk brake rotor and method for manufacturing same

Technical Field

The present invention relates to disc brakes for vehicles and more particularly to disc brake rotors.

Background

Larger and therefore heavier passenger vehicles (such as the so-called "sport utility vehicles" or the range of SUVs, etc.) are becoming increasingly popular, and disc brakes fitted to these vehicles have been required to increase in size. Similarly, the relative weight of electric vehicles, which is large due to their heavy batteries, has also required large disc brake systems, even though at least some of the braking force may be supplied by regenerative braking.

In addition to the increased thermal expansion and increased "unsprung weight" loading of these larger systems, they also present health and safety concerns for personnel who must lift and assemble the disc rotor for repair or replacement. These concerns have seen a shift away from the integrated disc rotor (where the braking band and mounting bell comprise a single integrated casting) towards a floating "hat" design where the mounting bell is a separate component of lighter material and is connected to the braking band in a manner that allows differential thermal expansion.

Examples of such hybrid systems are disclosed in the brenbo (Brembo) patents, US5810123, US8733517, and US 2014/0158486. Each of these discloses a cast iron brake band which is connected to a cast alloy mounting bell by a connector element. In the case of US5810123, short tabs project inwardly from the cast brake band to engage fork projections from the mounting bell, with the pins passing through apertures in both the tabs and the fork projections. US8733517 discloses an arrangement in which, in one embodiment, a projecting "drive element" engages a recess provided in the inner periphery of the brake band casting. In US2014/0158486, integral casting fingers project radially inwardly from the casting brake band to engage an annular groove around the periphery of the mounting bell.

A disadvantage of each of these systems is that the two opposing braking bands are effectively thermally isolated. In each of US5810123 and US2014/0158486 there is a minimum of cast material extending from the brake band that allows for heat dissipation, while in US8733517 there is no such. These prior designs incorporate a circular pattern of attachment mechanisms that produce variations in cross-sectional mass and therefore greater thermal gradients in these regions. These attachment mechanisms also interrupt the balanced flow of cooling air through the ventilation channel.

A disadvantage of the typical one-piece rotor, in which the mounting bell is cast integrally with the outer or inner brake band, is that a different thermal gradient is generated from the opposite brake band by means of the brake band connected to the mounting bell. This results in thermal distortion in the form of a cone, which reduces the effective contact surface and increases the tensile stress that leads to metal fatigue.

It is an object of the present invention to address or at least ameliorate some of the above disadvantages.

Attention is paid to

The term "comprising" (and grammatical variations thereof) is used in this specification in the inclusive sense of "having" or "including" and not in the exclusive sense of "consisting only of … …".

The above discussion of prior art in the context of the present invention is not an admission that any of the information discussed therein is part of the common general knowledge of the skilled person or of the prior art as may be referred to in any country.

Disclosure of Invention

Accordingly, in a first broad form of the invention, there is provided a disc brake rotor; the rotor includes opposing braking bands separated by an array of posts; the posts being integral with and extending between the opposite inner surfaces of the opposite brake bands; the rotor further comprises a connector ring structure forming an integral casting with the opposing braking band; the connector ring structure projects radially outward and inward from the inner ring of the posts of the post array.

Preferably, the column array comprises an inner ring of columns and an outer ring of columns.

Preferably, the radial line of the rotor passing through the centre of any column of the inner ring of columns is the bisector of the rotor passing through the radial line of the centre of the adjacent column of the outer ring of columns; adjacent columns are arranged on opposite sides of a radial line through the centers of the columns of the inner rings of columns.

Preferably, the connection between the opposing braking band and the connector ring structure passes through the inner ring of the post; the casting of the inner ring of the post is integral with the casting of the connector ring structure.

Preferably, opposite sides of the connector ring structure are spaced from opposite inner surfaces of the opposite braking band.

Preferably, the annular space between the opposite side of the connector ring structure and the opposite inner surface of the opposite braking band defines a ventilation inlet for air flow through the array of posts.

Preferably, the outer periphery of the connector ring structure is located substantially midway between the inner ring of the column and the outer ring of the column.

Preferably, the outer periphery of the connector ring structure is shaped such that the ventilation air flow passes through a venturi-like constriction between opposed inner surfaces of the brake band and formations on the outer surface of the connector ring structure, thereby increasing the volume of cooling air passing between the posts.

Preferably, the disc brake rotor is a component of a disc brake rotor assembly; the disc brake rotor assembly includes a disc brake rotor and a mounting bell for mounting the assembly to a wheel hub of a vehicle.

Preferably, the inner periphery of the connector ring structure is provided with a plurality of equally spaced inwardly directed projections; the projection is provided with an aperture adapted to receive therethrough a headed fastening bolt that fastens the mounting bell to the connector ring structure.

Preferably, the aperture is an elongate slot; the elongation of the slot provides for a radial sliding movement of the fastening bolt in the slot.

Preferably, the outer circumference of the central mounting bell is provided with apertures for receiving fastening bolts for assembling the central mounting bell to the connector ring structure.

Preferably, the opposing braking band, post array and connector ring structure form a one-piece casting with the mounting bell; a mounting bell projects outwardly from the inner periphery of the connector ring structure.

In another broad form of the invention, there is provided a method of manufacturing a disc brake rotor for a disc brake; the rotor includes opposing braking bands separated by an array of posts, the posts being integral with and extending between the inner surfaces of the opposing braking bands; the rotor further comprises a connector ring structure integrally connected with the inner ring of the posts of the post array; the method comprises the following steps:

two sand cores are formed, and the sand cores are formed,

placing the two sand cores back-to-back in a sand casting box, the sand casting box defining an outer surface of the disc brake rotor,

the casting of the rotor is carried out,

the casting is removed from the sand casting box,

the sand of the sand core is removed from the casting.

Preferably, each sand core conforms to a three-dimensional CAD solid model; the solid model defines a space between the median plane of the rotor and an inner surface of the braking band opposite the braking band and a space between the arrays of posts; a portion of the underside of each sand core defines an outer surface of the connector ring structure.

Preferably, a first sand core of the two sand cores conforms to the three-dimensional CAD solid model; the solid model defining a space between a median plane of the rotor and an inner surface of an outer one of the opposing braking bands and a space between the array of posts; the mock-up further defines an outwardly facing surface of a mounting bell integral with the connector ring structure.

Preferably, the second of the two sand cores conforms to a three-dimensional CAD solid model defining the space between the median plane of the rotor and the inner surface of the internal braking band opposite the braking band and the space between the array of posts; the mock-up further defines an inwardly facing surface of a mounting bell integral with the connector ring structure.

Preferably, the three-dimensional data of the three-dimensional CAD model is used for 3D printing of sand cores conforming to the three-dimensional solid CAD model.

Preferably, the rotor is part of a disc brake rotor assembly; the assembly includes a mounting bell releasably attached to the connector ring structure.

In another broad form of the invention, there is provided a disc brake rotor assembly; the assembly comprises a casting of the rotor and a casting of the mounting bell; the rotor includes opposing braking bands separated by an array of posts; the post is integral with and extends between the opposite inner surfaces of the opposite braking bands; the rotor further comprises a connector ring structure forming an integral casting with the opposing braking band; the connector ring structure projects radially outward and inward from the inner ring of the posts of the post array.

Preferably, the density of the cast material of the mounting bell is less than the density of the cast material of the rotor.

Preferably, the mounting bell is fixed to the inwardly projecting element at an inner periphery of the connector ring structure; the inwardly projecting element is provided with a radially elongated slot.

Preferably, the mounting bell is provided with a respective aperture at its outer periphery; headed mounting bolts are passed through the respective apertures through the radially elongated slots to secure the mounting bell.

Preferably, the elongated slot is used for differential expansion between the casting of the rotor and the casting of the mounting bell.

Drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

figure 1 is a perspective view of a disc brake rotor assembly according to a first preferred embodiment of the present invention,

fig. 2 is an elevation view of a rotor casting of the disc brake rotor assembly of fig. 1, showing hidden details of the array of posts interconnecting opposing braking bands,

figure 2A is a perspective view of the rotor casting of figure 2,

figure 3 is a cross-sectional end view of the rotor casting of figures 2 and 2A,

figure 4 is an enlarged view of a portion of the cross-section of figure 3 taken on a radial line through the opposing pair of columns of the outer ring of columns,

figure 4A is a similar enlarged portion taken on a radial line through the opposing pair of columns of the inner ring of columns,

figure 5 is a cross-sectional view of the rotor casting and the central mounting bell of the connector ring structure secured to the rotor casting,

figure 6 is an enlarged view of a portion of the cross-sectional view of figure 5,

figure 7 is a perspective view of the outer surface of one of a pair of identical sand cores used to produce the casting of the rotor of figures 2-7,

figure 8 is a perspective view of the opposite face of one of the pair of identical sand cores of figure 7,

fig. 9 is a cross-sectional view of two of the same cores of fig. 7 placed back-to-back, for casting the rotor of fig. 2-6,

figure 10 is a perspective view of a further preferred embodiment of a disc brake rotor according to the present invention,

fig. 11 is a cross-sectional view of the disc brake rotor of fig. 10.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

First preferred embodiment

Referring to fig. 1 to 6, a discbrake rotor assembly 10 according to this first preferred embodiment of the present invention includes arotor 12 and a mountingbell 13 for mounting to a hub (not shown) of a vehicle. Therotor 12 includes opposingbraking bands 14, 16 separated by an array ofposts 18. As is well known in the art, thepost 18 is integral with the opposedinner surfaces 20, 22 of the opposed braking bands, and thepost 18 extends between the opposedinner surfaces 20, 22.

Therotor 12 further includes aconnector ring structure 24, theconnector ring structure 24 being formed as a one-piece casting with the opposingbraking bands 14, 16 and with thepost 18.Connector ring structure 24 projects radially outwardly and inwardly from the inner ring ofposts 26 of the array ofposts 18. As can be seen in fig. 2 (and also in fig. 4A), theouter periphery 28 of theconnector ring structure 24 is located approximately midway between the inner ring of thepost 26 and the outer ring of thepost 30.

It is also clear from fig. 4A that the connection between the opposingbraking bands 14, 16 and theconnector ring structure 24 is achieved by means of the posts of the inner ring ofposts 26, so that theposts 26 of the inner ring can be considered to "pass through" theconnector ring structure 24 in a sense even if the inner posts and the connector ring form a one-piece casting.

Referring particularly to fig. 2, it can be seen that the inner and outer rings ofposts 26, 30 are arranged such that theradial line 32 of therotor 12 is a bisector of theradial lines 34, 36 of the rotor, theradial line 32 passing through the centre of any post of the inner ring ofposts 26, the radial lines 34, 36 passing through the centre of the adjacent post of the outer ring ofposts 30; the adjacent columns are disposed on opposite sides of theradial line 32.

As best seen in fig. 4, theconnector ring structure 24 is dimensioned in thickness such that opposing surfaces 36, 38 of theconnector ring structure 24 are spaced from opposinginner surfaces 20, 22 of opposingbraking bands 14, 16, thereby providing an annular space defining a ventilation inlet for air flow through the array of posts. This design enables uniform flow of cooling air from both the inside and outside directions while maintaining a consistent cross-sectional area across the entire diameter of the brake band.

As can also be seen in fig. 3 and 4, theperiphery 28 of the connector ring structure is shaped so that the ventilation air flow passes through a venturi-like constriction betweenformations 40, 42 on the inner surface of the brakingbands 14, 16, thereby increasing the velocity and volume of cooling air passing between theposts 18.

As shown in fig. 2 and 4, theinner periphery 44 of theconnector ring structure 24, which extends inwardly to project from between the opposingbrake bands 14, 16, is provided with a plurality of equally spaced, inwardly directedprojections 46, eachprojection 46 being provided with anaperture 47, theapertures 47 being adapted to receive afastening bolt 48 of the band head therethrough (as shown in fig. 1, 5 and 6) for fastening the mountingbell 13 to the connector ring structure, as shown in fig. 5 and 6. Theaperture 47 is in the form of an elongate slot in which the long axis of the slot is radially aligned with the centre of the rotor. The width of theaperture 47 is such as to provide a sliding fit clearance for the shoulder diameter of thebolt 48, so the elongation of the slot provides for radial sliding movement of the fastening bolt in the aperture to allow differential thermal expansion of therotor 12 relative to the mounting bell 11. Preferably, the headedfastening bolt 48 is threaded and retained by a lockingnut 50.

Therotor 12 is manufactured by casting. First, a CAD solid model is prepared that defines an interior space between themedian plane 51 of the rotor and the inner surface of the brake band, the posts of the post array, and the outer surface of the connector ring structure. The CAD data can be used to produce a mold (not shown), for example by CNC machining or by 3D printing. The mold may then be used to form two identical sand cores, one of which is shown in fig. 7 as twoidentical sand cores 52. More preferably, the twosand cores 52 and 54 (both sides of one of which are shown in fig. 7 and 8) may be 3D printed directly from CAD data.

As shown in fig. 9, twosuch sand cores 52 and 54 are placed back-to-back, outwardly facing sides 56, 58 to define theinner surfaces 40, 42 of the opposingbraking bands 14, 16, with apertures 55 (see fig. 7 and 8) defining an array ofposts 18. When the sand cores are placed back-to-back as shown in fig. 9, the cavities 64 (see fig. 8) formed on the respective back sides 60, 62 of thesand cores 52 and 54 combine to define theconnector ring structure 24.

The casting in which the bell is mounted is of a material less dense than the casting of the rotor, thereby allowing a significant reduction in the weight of the rotor assembly, with attendant health and safety benefits and a reduction in the unsprung weight of the vehicle in which the assembly is fitted.

Second preferred embodiment

In this preferred embodiment, now referring to fig. 10 and 11, thedisc brake rotor 112 according to the present invention is in the form of a one-piece casting. As in the first preferred embodiment described above, the rotor 100 includes opposing brakingbands 114, 116 interconnected by an array ofposts 118, theposts 118 being disposed in theinner ring 126 and theouter ring 130, as described above.

Also in this embodiment, therotor 112 further includes aconnector ring structure 124, theconnector ring structure 124 projecting inwardly from between thebrake bands 114, 116 as described above for the first embodiment, theconnector ring structure 124 being integral with the inner ring of thepost 126. As can be seen from the cross-sectional view of fig. 11, theconnector ring structure 124 of this embodiment is configured at itsouter periphery 128 in the same manner as described above.

However, in this embodiment, theconnector ring structure 124 is formed as a one-piece casting with the mountingbell 113 extending from theinner periphery 144 of the connector ring structure.

The method of casting the rotor 100 of this embodiment and itsintegral mounting bell 113 is similar in principle to that described for the first embodiment above, but with a sand core now incorporating the form of the mountingbell 113. As previously described, each of the two sand cores is formed from a model of the space forming thebraking band 114, 116, the array ofposts 118 and the connector ring and, in this embodiment, the interior region between the outer surfaces of the mountingbell 113, which can be derived from a solid CAD modeling of the rotor and resulting sand core, preferably by 3D printing.

The first of the two sand cores conforms to a three-dimensional CAD solid model defining the space between the median plane of the rotor and the inner surface of the outer one of the opposing braking bands and between the array of posts. The solid model further defines the outwardly facing surface of mountingbell 113. The second of the two sand cores conforms to a three-dimensional CAD solid model defining a space between the median plane of the rotor and the inner surface of the inner brake band, a space between the array of posts, and an inwardly facing surface on which the bell is mounted.

Claims (24)

1. A disc brake rotor, the rotor comprising opposed braking bands separated by an array of posts; the posts being integral with and extending between the opposite inner surfaces of the opposite braking bands; the rotor further comprising a connector ring structure forming a unitary casting with the opposing braking band; the connector ring structure projects radially outward and inward from the inner ring of the posts of the post array.

2. The disc brake rotor of claim 1, wherein the array of posts includes an inner ring of posts and an outer ring of posts.

3. The disc brake rotor of claim 2, wherein a radial line of the rotor passing through the center of any of the inner rings of columns is a bisector of a radial line of the rotor passing through the center of an adjacent column of the outer ring of columns; the adjacent columns are arranged on opposite sides of the radial line passing through the center of the column of the inner ring of columns.

4. A disc brake rotor according to claim 2 or 3, wherein the connection between the opposing braking bands and the connector ring structure passes through the inner ring of the post; the casting of the inner ring of the post is integral with the casting of the connector ring structure.

5. The disc brake rotor of claim 1, wherein opposite sides of the connector ring structure are spaced from opposite inner surfaces of the opposite braking bands.

6. The disc brake rotor of claim 5, wherein an annular space between opposite sides of the connector ring structure and opposite inner surfaces of the opposite brake bands defines a vent inlet for air to flow through the array of posts.

7. The disc brake rotor of any one of claims 2-6, wherein the outer periphery of the connector ring structure is located approximately midway between the inner ring of the column and the outer ring of the column.

8. The disc brake rotor of claim 7, wherein the outer periphery of the connector ring structure is shaped such that a flow of ventilation air passes through a venturi-like constriction between opposing inner surfaces of the brake band and formations on an outer surface of the connector ring structure, thereby increasing the volume of cooling air passing between the posts.

9. The disc brake rotor of any one of claims 1 to 8, wherein the disc brake rotor is a component of a disc brake rotor assembly; the disc brake rotor assembly includes the disc brake rotor and a mounting bell for mounting the assembly to a wheel hub of a vehicle.

10. The disc brake rotor of claim 9, wherein the inner periphery of the connector ring structure is provided with a plurality of equally spaced inwardly directed projections; the projection is provided with an aperture adapted to receive a headed fastening bolt therethrough, the fastening bolt fastening the mounting bell to the connector ring structure.

11. The disc brake rotor of claim 10, wherein the aperture is an elongated slot; the elongation of the slot provides for a radial sliding movement of the fastening bolt in the slot.

12. A disc brake rotor according to claim 10 or 11, wherein the outer periphery of the central mounting bell is provided with apertures for receiving fastening bolts for assembling the central mounting bell to the connector ring structure.

13. The disc brake rotor of any one of claims 1 to 8, wherein the opposing braking bands, the post array and the connector ring structure form a one-piece casting with a mounting bell; the mounting bell projects outwardly from an inner periphery of the connector ring structure.

14. A method of manufacturing a disc brake rotor for a disc brake, the rotor comprising opposed braking bands separated by an array of pillars, the pillars being integral with inner surfaces of the opposed braking bands and the pillars extending between the inner surfaces of the opposed braking bands; the rotor further comprising a connector ring structure integrally connected with the inner ring of the posts of the post array; the method comprises the following steps:

-forming two sand cores,

-placing the two sand cores back-to-back in a sand casting box; the sand casting box defines an outer surface of the disc brake rotor,

-casting the rotor in a mold,

-removing the casting from the sand casting box,

-removing sand of the sand core from the casting.

15. The method of claim 14, wherein each sand core conforms to a three-dimensional CAD solid model; the solid model defines a space between a median plane of the rotor and an inner surface of a braking band of the opposing braking band and a space between the array of posts; a portion of the underside of each sand core defines an outer surface of the connector ring structure.

16. The method of claim 14, wherein a first of the two sand cores conforms to a three-dimensional CAD solid model; the solid model defines a space between a median plane of the rotor and an inner surface of an outer one of the opposing braking bands and a space between the array of posts; the mock-up further defines an outwardly facing surface of a mounting bell integral with the connector ring structure.

17. The method of claim 14, wherein a second sand core of the two sand cores conforms to a three-dimensional CAD solid model defining a space between a median plane of the rotor and an inner surface of an inner brake band of the opposing brake bands and a space between the array of pillars; the mock-up further defines an inwardly facing surface of a mounting bell integral with the connector ring structure.

18. The method of any of claims 14 to 17, wherein the three-dimensional data of the three-dimensional CAD model is used for 3D printing of the sand core conforming to the three-dimensional solid CAD model.

19. A method according to any one of claims 17 or 18, wherein the rotor is part of a disc brake rotor assembly; the assembly includes a mounting bell releasably attached to the connector ring structure.

20. A disc brake rotor assembly, the assembly comprising a casting of a rotor and a casting of a mounting bell; the rotor includes opposing braking bands separated by an array of posts; the posts being integral with and extending between the opposite inner surfaces of the opposite braking bands; the rotor further including a connector ring structure forming a unitary casting with the opposing braking bands; the connector ring structure projects radially outward and inward from the inner ring of the posts of the post array.

21. The disc brake rotor assembly of claim 20, wherein the cast material of the mounting bell has a density less than the cast material of the rotor.

22. The assembly of claim 20 or 21, wherein the mounting bell is fixed to an inwardly projecting element at an inner periphery of the connector ring structure; the inwardly projecting element is provided with radially extending slots.

23. The assembly of claim 22, wherein the mounting bell is provided with respective apertures at its outer periphery; a headed mounting bolt passes through the corresponding aperture through the radially elongated slot to secure the mounting bell.

24. The assembly of claim 22 or 23, wherein the elongate slot is for differential expansion between the casting of the rotor and the casting of the mounting bell.

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