WO2002064992A2

WO2002064992A2 - An improved rotor for self-ventilating disc brakes

Info

Publication number: WO2002064992A2
Application number: PCT/AU2001/000464
Authority: WO
Inventors: Stephen Patrick Gavin
Original assignee: Disc Brakes Australia Pty. Ltd.
Priority date: 2001-02-12
Filing date: 2001-04-23
Publication date: 2002-08-22
Also published as: AUPR304801A0; WO2002064992A3

Abstract

A disc brake rotor which includes a central hub (1) co-axial with surrounding annular rings (3) which form brake bands for engagement with brake pads. The rings (3) are supported in a parallel spaced apart configuration by a plurality of pillars (6) between them which are arranged in clusters to form a series of overlapping edges and channels. In use of the rotor cooling air is drawn radially outward through the channels as the rotor turns. The pillars (6) are disposed in staggered tiers to facilitate the distribution of support against heat distortion.

Description

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 disc brake rotors typically comprise a hub section co-axial with a surrounding annular ring and brake band 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 adjacent air channels. Disadvantages with such existing rotors include distortion caused by uneven heat dissipation and inadequate support by the fins.

SUMMARY OF THE INVENTION It is therefore an object of this invention to ameliorate the aforementioned disadvantages and accordingly a disc brake rotor is disclosed, said rotor including a central hub co-axial with surrounding annular rings which form brake bands for engagement with brake pads wherein said rings are supported in a spaced apart conf guration by a plurality of pillars therebetween which are arranged in clusters to form a series of overlapping edges and channels whereby cooling air is drawn radially outward through said channels as the rotor is rotated and said pillars being further disposed in staggered tiers to facilitate the distribution of support against heat distortion.

Preferably said rotor further includes inlet ports to said channels which are separated by intake blades formed around the inner periphery of said rings to draw air into the channels.

BRIEF DESCRIPTION OF THE DRAWINGS One currently preferred embodiment of this invention will now be described with reference to the attached drawings in which:

Figure 1 is a schematic perspective view of a self-ventilating disc brake rotor according to this concept. Figure 2 is a cross-sectional view of the rotor along the lines A-A of figure 1, Figure 3 is a sectional view along the lines B-B of figure 1, Figure 4 is a detail of area V of figure 3, 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 conf guration 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.

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 impel ler.

While the invention is not limited to any specific cross- sectional 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 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 mm² and 60 mm².

With the described embodiment the middle tier pillars are each about 51 mm² in cross-sectional area. As shown in figure 5 the corners are rounded with radii A of 1.2 mm, B of 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. 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 ² . 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

The claims defining the invention are as follows:

1. A disc brake rotor including a central hub co-axial with surrounding annular rings which form brake bands for engagement with brake pads wherein said rings are supported in a parallel spaced apart conf guration by a plurality of pillars therebetween which are arranged in clusters to form a series of overlapping edges and channels whereby in use of the rotor cooling air is drawn radially outward through said channels as the rotor turns and said pillars being further disposed in staggered tiers to facilitate the distribution of support against heat distortion.

2. The disc brake rotor as claimed in claim 1 wherein said pillars are disposed in radially inner, middle and outer tiers.

3. The disc brake rotor as claimed in claim 2 wherein said rotor further includes inlet ports to said channels which are defined between intake blades formed around the inner periphery of said rings.

4. The disc brake rotor as claimed in claim 3 wherein 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.

5. The disc brake rotor as claimed in claim 4 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.

6. The disc brake rotor as claimed in claim 5 wherein said intake blades have an elongated cross-sectional shape.

7. The disc brake rotor as claimed in claim 6 wherein the pillars forming said middle tier have a triangular cross- sectional shape with rounded corners.

8. The disc brake rotor as claimed in claim 7 wherein the pillars forming said inner tier have a tear-drop cross- sectional shape with rounded inner and outer ends.

9. The disc brake rotor as claimed in claim 8 wherein the pillars forming said outer tier have a wedge cross- sectional shape with a rounded inner end.

10. The disc brake rotor as claimed in claim 9 wherein the cross-sectional area of each pillar forming said middle tier is between about 50 mm 2 and 60 mm?.