AU770030B2 - An improved rotor for self-ventilating disc brakes - Google Patents

Description

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: PR3048 Filed 12 February, 2001 Related Art: Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: Complete Specification TO BE COMPLETED BY APPLICANT Disc Brakes Australia Pty. Ltd Unit 33, Slough Business Park, Holker Street, SILVERWATER NSW 2128 Stephen Patrick Gavin P&4BDE)OO TAkaLR &ASSECCISE, floqiatetae paten~t emf 1 IIriczr BEvzrEuz DCNID Y N.S.W. 2RP6 C WALLhJG.rTOW-DUMM~f 60A j qjI 9PALMEgi IiSW 1-701 AUSTEALWA ADDRESS FOR SERVICE 0 for the invention AL.TERED AN IMPROVED ROTOR FOR SELF-VENTILATING DISC BRAKES The following statement is a full description of this invention, including the best method of performing it known tome:

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12.Dec. 2003 17:08 Wallington-Dummer Sydney No.3748 P. AN IMPROVED ROTOR FOR SELF-VENTILATING DISC BRAKES BACKGROUND OF THE INVENTION This invention relates to brake apparatus. More particularly although not exclusively it discloses an improved rotor for vehicle disc brakes.

Existing 4isc brake rotors typically comprise a hub section co-axial with a surrounding annular ring and brake Sband which is adapted for frictional contact with caliper operated pads on each side. With self-ventilating disc brakes there are two spaced apart parallel bands provided on each rotor which are cooled by a radial flow of air outwardly through channels formed between them. This flow largely results from centrifugal forces generated by rotation of the rotor. With prior art rotors the bands are normally separated by radial fins. As well as supporting :the bands the fins act as radiation elements which dissipate heat into the adjdcent air channels.

Disadvantages with such existing rotors include distortion caused by uneven heat dissipation and inadequate support by the fins.

COMS ID No: SMBI-00533783 Received by IP Australia: Time 18:26 Date 2003-12-12 12.Dec. 2003 17:08 Wallington-Dummer Sydney No,3748 P. 6 Summary of the Invention Accordingly, in one broad form of the invention, there is provided a disc brake rotor having a central hub coaxial with and supporting annular rings which form an inboard brake disc and an outboard brake disc for engagement with brake pads, said inboard disc and said outboard disc maintained in a parallel spaced apart configuration by pillars with channels defined between said pillars whereby in use of the rotor air is drawn in through vent means and then radially outwardly through said channels as the rotor turns, said pillars arranged in repeating clusters of six with each cluster in cross section including radially aligned inner and outer pillars with pairs of radially aligned intermediate pillars positioned symmetrically one pair on each side of a radially aligned central axis defined by said radially aligned inner S..and outer pillars; each pair of said pairs of radially aligned' intermediate pillars defining a channel between the pillars comprising said pair; said channel offset from a radially aligned direction.

Preferably said pillars are arranged in clusters with each cluster being symmetrical with respect to rotational directions of the rotor.

Preferably each cluster defines a respective pair of the channels and cooling air passes equally through one or the other thereof in accordance with the direction of rotor rotation.

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COMS ID No: SMBI-00533783 Received by IP Australia: Time 18:26 Date 2003-12-12 12.Dec. 2003 17:09 Wallington-Dummer Sydney No.3748 P. 7 Preferably each cluster includes pillars which in crosssection are of elongated triangular shape and have overlapping edges to define said pair of the channels.

Preferably said pillars are disposed in radially inner, middle and outer tiers.

Preferably said rotor further includes inlet ports to said channels which are defined between intake blades formed around the inner periphery of said rings.

Preferably the layout of pillars within each of said clusters is symmetrical with respect to rotation of the rotor whereby an equal flow of cooling air is obtained irrespective of rotational direction.

Preferably said inlet ports are formed with a protruding lip and a curve adapted to smoothly direct the cooling air into said channels.

Preferably said intake blades have an elongated crossp S" sectional shape.

.o E Preferably the pillars forming said middle tier have a triangular cross-sectional shape with rounded corners.

Preferably the pillars forming said inner tier have a teardrop cross-sectional shape with rounded inner and outer ends.

Preferably the pillars forming said outer tier have a wedge cross-sectional shape with a rounded inner end.

Preferably the cross-sectional area of each pillar forming said middle tier is between about 50 mm 2 and 60 mm 2 COMS ID No: SMBI-00533783 Received by IP Australia: Time 18:26 Date 2003-12-12 12.Dec. 2003 17:09 Wallington-Dummer Sydney No.3748 P. 8 noe 009000 0 0 *0 •0 O 0 0 o* 0 0 9 6-90 *0 0 0 BRIEF DESCRIPTION OF THE DRAWINGS One currently preferred embodiment of this invention will now be described with reference to -he atthched drawings in which: Figure 1 Figure 2 Figure 3 Figure 4 is a schematic perspective view of..'a self-ventilating disc "irake rotor according to this concept, is a cross-sectional view of the rotor along the lines A-A of figure 1, is a sectional view along the lines B-B of figure 1.

is a detail of area V of figure 3, -3- COMS ID No: SMBI-00533783 Received by IP Australia: Time 18:26 Date 2003-12-12 Figure 5 is a detail of area W of figure 3. and Figures 6, 7 and 8 show enlarged cross-sectional views of the inner, middle and outer tier pillars, being details of areas X, Y, and Z of figure 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to figures 1 and 2 the rotor may be cast as one piece from material which includes G220 grey iron.

It may comprise a hub 1 for mounting a vehicle wheel by means of bolts (not shown) passing through apertures 2.

Surrounding the hub and co-axial with it are annular rings 3 and 4. The outer surfaces of these rings form brake bands 5 adapted for frictional engagement with caliper mounted brake pads (not shown) As best shown in figure 3 the rings are supported in a parallel spaced apart configuration by a plurality of pillars 6 between them which are cast as one piece with said rings.

Preferably the pillars are arranged in middle, outer and inner tiers 6A, 6B and 6C as shown in figure 4.

The pillars are preferably further arranged in repeating clusters or patterns of six units as delineated by broken line 7 in figure 4. They are also positioned to minimise the unsupported spans between the rings and thereby reduce distortion from heat and braking stresses. This is obtained by staggering or offsetting the middle tiers 6A in relation to the inner and outer tiers 6B and 6C as best shown in figure 4.

Preferably the junctions of the pillars 6 with the inside surface of the rings 3 and 4 are radiused as indicated by lines 7A to prevent stress concentrations.

As shown in figure 5 the aforementioned tiers of pillars are also shaped and positioned to form a series of overlapping blades or edges 8. During rotation of the rotor air is forced radially out through channels 9 between the rings as indicated by arrows 10 and 11 in figure 4. It will be appreciated from this sectional view that the symmetrical layout of the pillar clusters with respect to rotation of the rotor enables an equal air flow to be obtained irrespective of rotational direction. The need for dedicated left and right rotors is thus avoided with savings in manufacturing costs.

*.o A further important feature of the invention comprises the novel and unique shape of the inlet ports 12 located around the inside periphery of the rings. Each intake port is defined between intake blades 13. As best shown in figure 2 the ports are formed with a protruding lip 14 and gently flowing curve 15 which smoothly direct the the air into the channels 9 with a minimum of turbulance. The intake of air through the ports is further assisted by the elongated shape and the position of the intake blades (see -figure 4) which in operation simulate the blades of an impeller.

While the invention is not limited to any specific crosssectional shape and size for the pillars and intake blades the middle tier of pillars 6A are preferably triangular in cross-section with rounded corners. This shape has been found to enable a stronger sand core to be produced for the casting process by reducing porosity around the pillar cavities. With prior art diamond and oval shaped pillars i air pockets commonly form in the sand core adjacent the pillar cavities as the casting sand is blown in. In order to provide sufficient strength without unacceptable heat buildup the cross-sectional area of the middle tier "pillars is preferably between about 50 mm 2 and 60 mm 2 With the described embodiment the middle tier pillars are each about 51 mm 2 in cross-sectional area. As shown in figure 5 the corners are rounded with radii A of 1.2 mm, B Sof 1.5 mm and C of 2.5 mm. Other sizes and shapes however may be suitable for some applications.

Each of the pillars forming the inner tier 6B as shown in figure 7 is of the tear-drop shape with a cross-sectional area preferably of about 50 mm 2 The inner and outer ends are rounded with radii D of 3 mm and E of 1.5 mm. Other sizes and shapes however may be suitable for some applications.

-6- Each of the pillars forming the outer tier 6C is preferably wedge shaped in cross-section as shown in figure 8 with an area of about 47 mm The inner end is rounded to a radius F of 1.5 mm. Again other sizes and shapes may be suitable for some applications.

It will thus be appreciated that this invention at least in the form of the embodiment disclosed comprises a novel and improved form of disc brake rotor. Clearly however the example described in only the currently preferred form of this invention and a wide variety of modifications may be made which would be apparent to a person skilled in the art. For example the design of the hub and brake bands may be changed to suit different vehicles. The number, shape and configuration of the pillars and intake blades may also be varied according to application.

Claims (1)

12.Dec. 2003 17:09 Wallington-Dummer Sydney No.3748 P. 9 8 The claims defining the invention are as follows: 1. A disc brake rotor having a central hub coaxial with and supporting annular rings which form an inboard brake disc and an outboard brake disc for engagement with brake pads, said inboard disc and said outboard disc maintained in a parallel spaced apart configuration by pillars with channels defined between said pillars whereby in use of the rotor air is drawn 10 in through vent means and then radially outwardly through said channels as the rotor turns, said pillars arranged in repeating clusters of six with each cluster .i in cross section including radially aligned inner and 9e outer pillars with pairs of radially aligned intermediate pillars positioned symmetrically one pair. on each side of a radially aligned central axis defined by said radially aligned inner and outer pillars; each pair of said pairs of radially aligned intermediate pillars defining a channel between the pillars comprising said pair; said channel offset from a radially aligned direction. 2. The disc brake rotor as claimed in claim 1 wherein said pillars are arranged in clusters with each cluster being symmetrical with respect to rotational directions of the rotor. 3. The disc brake rotor as claimed in claim 2 wherein each COMS ID No: SMBI-00533783 Received by IP Australia: Time 18:26 Date 2003-12-12 12-Dec. 2003 17:09 Wallington-Dummer Sydney No 3748 P 9 cluster defines a respective pair of the channels and c.ooling air passes equally through one or the other thereof in accordance with the direction of rotor rotation. 4. The disc brake rotor as claimed in claim 3 wherein each cluster includes pillars which in cross-section are of elongated triangular shape and have overlapping edges to define said pair of the channels. The disc brake rotor as claimed in claims I to 4 wherein said pillars are disposed in radially inner, middle and outer tiers. 6. The disc brake rotor as claimed in claims 1 to wherein said rotor further includes inlet ports to said channels which are defined between intake blades formed around the inner peripbery of said rings. 7. The disc brake rotor as claimed in claims I to 6 wherein the layout of pillars within each of said clu. ters is symmetrical with respect to rotation of the rotor whereby an equal flow of cooling air is obtained irrespective of rotati.ona direction. B. The disc brake rotor as claimed in claims I to 7 wherein each said of said inlet ports is formed with a protruding lip and a curve adapted to smoothly direct the cooling air into said channels. 9. The disc brake rotor as claimed in claims 1 to 8 wherein said intake blades have an elongated cross- COMS ID No: SMBI-00533783 Received by IP Australia: Time 18:26 Date 2003-12-12 12,Dec. 2003 17:09 Wal I ington-Dummer Sydney No.3748 P. 11 10 sectional shape. The disc brake rotor as claimed in claims 1 to 9 wherein the pillars forming said middle tier have a triangular cross-sectional shape with rounded corners. 11. The disc brake rotor as claimed in claims 1 to wherein the pillars forming said inner tier have a tear-drop cross-sectional shape with rounded inner and outer ends. 12. The disc brake rotor as claimed in claims 1 to 11 IM wherein the pillars forming said outer tier have a wedge cross-sectional shape with a rounded inner end. The disc brake rotor as claimed in claims 1 to 12 J wherein the cross-sectional area of each pillar forming S C said middle tier is between about 50 mm 2 and 60 mm 2 i a C e* DATED: 12 December 2003 S 54O S 0 0@ C DISC BRAKES AUSTRALIA PTY LTD by their Patent Attorneys: WALLINGTON-DUMMER COMS ID No: SMBI-00533783 Received by IP Australia: Time 18:26 Date 2003-12-12