U.S. patent application number 09/754688 was filed with the patent office on 2002-07-04 for disc brake rotor.
This patent application is currently assigned to DELPHI AUTOMOTIVE SYSTEMS.. Invention is credited to Ballinger, Robert S., Dunlap, Kenneth B., Riehle, Michael A..
Application Number | 20020084155 09/754688 |
Document ID | / |
Family ID | 25035876 |
Filed Date | 2002-07-04 |
United States Patent
Application |
20020084155 |
Kind Code |
A1 |
Ballinger, Robert S. ; et
al. |
July 4, 2002 |
Disc brake rotor
Abstract
A disc brake including a pair of friction plates arranged
coaxially in a parallel, spaced-apart relationship and a plurality
of vanes extending between the pair of friction plates, each of
said vanes having a proximal end, a distal end and a mid-portion
extending between the proximal end and the distal end, the proximal
ends of a plurality of the vanes having a first width, the
mid-portion having a second width, the first width being
substantially greater than the second width. The vanes can include
a T-shaped portion adjacent the proximal end.
Inventors: |
Ballinger, Robert S.; (West
Chester, OH) ; Dunlap, Kenneth B.; (Springfield,
OH) ; Riehle, Michael A.; (West Chester, OH) |
Correspondence
Address: |
SCOTT A. MCBAIN
DELPHI TECHNOLOGIES, INC.
Legal Staff, Mail Code: 482-204-450
1450 W. Long Lake
Troy
MI
48098
US
|
Assignee: |
DELPHI AUTOMOTIVE SYSTEMS.
|
Family ID: |
25035876 |
Appl. No.: |
09/754688 |
Filed: |
January 3, 2001 |
Current U.S.
Class: |
188/218XL ;
188/205A; 188/73.37 |
Current CPC
Class: |
F16D 65/12 20130101;
F16D 2065/1328 20130101; F16D 65/0006 20130101 |
Class at
Publication: |
188/218.0XL ;
188/205.00A; 188/73.37 |
International
Class: |
F16D 065/38 |
Claims
1. A rotor for a disc brake comprising: a pair of friction plates
arranged coaxially in a parallel, spaced-apart relationship; and a
plurality of vanes extending between the pair of friction plates,
each of the vanes having a proximal end, a distal end and a
mid-portion extending between the proximal end and the distal end,
the proximal end of a plurality of the plurality of vanes including
a first width, the mid-portion including a second width, the first
width being greater than the second width.
2. The rotor of claim 1 wherein the first width is substantially
greater than the second width.
3. The rotor of claim 2 wherein the vanes other than the vanes
having the first width have a third width, the third width being
substantially the same as the second width.
4. The rotor of claim 2 wherein the first width is about 50 percent
greater than the second width.
5. The rotor of claim 1 wherein the first width is about twice that
of the second width.
6. The rotor of claim 1 wherein a plurality of the plurality of
vanes includes an inverted T-shaped portion adjacent the proximal
end of the vanes.
7. The rotor of claim 6 wherein at least half of the vanes include
an inverted T-shaped portion adjacent the proximal end of the
vanes.
8. The rotor of claim 6 wherein the inverted T-shaped portion is at
least 50% wider than the second width.
9. The rotor of claim 6 further comprising an angled portion
located between each inverted T-shaped portion and a respective
mid-portion.
10. A method of reducing noise in a disc brake rotor comprising:
stiffening a radially inner portion of the brake rotor with a
proximal portion of a plurality of vanes; and reducing hybrid
vibration modes in an audible frequency range.
11. The method of claim 10 wherein the proximal portion of the
plurality of vanes includes an inverted T-shaped portion.
12. The method of claim 11 wherein at least one half of the
plurality of vanes include an inverted T-shaped portion at the
proximal portion.
13. The method of claim 12 wherein each vane other than the lat
least one half of the plurality of vanes includes a substantially
constant width from a proximal portion to a distal portion.
14. A rotor for a disc brake comprising: means for stiffening a
radially inner portion of the brake rotor with a proximal portion
of a plurality of vanes; and means for reducing hybrid vibration
modes in an audible frequency range.
15. The rotor of claim 14 wherein the proximal portion of the
plurality of vanes includes an inverted T-shaped portion.
16. The rotor of claim 15 wherein at least one half of the
plurality of vanes include an inverted T-shaped portion at a
proximal portion.
17. The rotor of claim 16 wherein each vane other than the at least
one half of the plurality of vanes include a substantially constant
width from a proximal portion to a distal portion.
Description
TECHNICAL FIELD
[0001] The present invention relates generally to disc brake rotors
as used in a vehicle braking system. More particularly, the
invention relates to a vehicle brake rotor that incorporates a
plurality of vanes designed to reduce noise generated in the brake
system.
BACKGROUND OF THE INVENTION
[0002] Noise generated during a brake application has been
increasing as the size of vehicles has been decreasing. Attempts
have been made to reduce the noise generated using various systems
and methods. One such technique involves the use of sound
adsorption coatings on the pad assembly. While such coatings have
some effectiveness, the addition of the coating adds cost to the
manufacture and at times, undesirable noise occurs when the
thickness of the coating has not been uniform.
[0003] Another technique involves a disc brake pad assembly having
clench tabs extending through rubber-like grommets in openings in a
caliper housing leg so that the grommets are retained in the
openings and the brake pad assembly is retained on the housing leg.
The grommets provide a noise dampening action during braking to
reduce noise.
[0004] Individual noise problems have been reduced through the
modification of the ingredients in the composition of materials
that make up a brake pad. In many of these cases, while noise may
have been abated somewhat, the braking effectiveness of the system
has been changed by the modification of the brake pad material.
Still another technique of reducing brake noise involves affixing a
ring damper about a periphery of a brake rotor in a disc brake
system. The ring damper is held in place by a groove formed in the
periphery of the disc and is pre-loaded against the rotor both
radially and transversely.
[0005] The above techniques involve the reduction of noise by
absorbing or masking the noise after it has been created or by
adding costly complexity to the braking system. It would be
advantageous to design the system to reduce the potential for the
creation of noise. It has been suggested that much of brake squeal
or noise is influenced by the excitation of the natural frequencies
of a rotor caused by the rubbing of friction pads on a rotor
surface. There is evidence that a disc brake rotor may have a dozen
or more naturally occurring frequencies. While most of these are in
the axial direction, others are in the torsional direction. In
simulated braking applications only certain of these natural
frequencies create brake noise or squeal. Every natural frequency
of a vibrating system has associated with it a mode shape that
describes the pattern of deformation associated with that natural
frequency. In a continuous structure, the mode shape is generally
accepted or described by defining the pattern of nodes (loci of
points of zero deformation) on the surface of the structure.
Experiments have shown that the mode shape of an annular circular
plate, a shape like that of a brake rotor, includes nodal circles
and diameters. Thus, a beneficial effect on brake noise should be
attainable if the nodal diameter modes of an installed disc rotor
are maintained at a maximum separation, thereby reducing or
eliminating coupling of the nodal diameter modes in the audible
frequency range.
[0006] A typical structure of a brake rotor includes a central disc
portion that is adapted to be mounted to an axle of a vehicle as in
known in the art, by fasteners. An extending portion typically
connects one of a pair of rotor friction plates or cheeks to the
central disc portion. An outboard plate is the portion of the rotor
that includes a friction surface attached to the central disc
portion adjacent to the wheel and faces outward from the vehicle
body. An inboard plate faces inward toward the vehicle body.
[0007] A plurality of vanes extend from an inner surface of the
first or outboard plate to connect a second inboard plate thereto.
The vanes are typically arranged in a radial fashion about the
rotor. The vanes hold the first and second plates in a parallel,
side-by-side relationship. Typically, vanes have an overall regular
elongate, rod, coffin or rectangular shape with a generally
constant width and cross-sectional area. In other words, many
current vanes start out a rectangular cross-section at one end and
remain rectangular throughout the longitudinal distance of the vane
at an opposite end. Similarly, a prior-art plate typically has a
thickness or cross-section remaining substantially constant along
the radial direction.
[0008] A rotor may possess a number of inherent resonance modes. In
use, the rotor may generate vibrations including a mode
characterized by radial (and potentially transverse and some
tangential) displacement of the plates of the rotor. Further, the
rotor may generate vibrations in a mode referred to as an X-mode,
characterized by mainly transverse (with some radial and
tangential) displacement of the plates of the rotor. A transverse
modal vector is defined by one nodal diameters at the friction
radius of the rotor and X order nodal diameters defined by the
number of transverse antinodes. Coupling of a radial and an X-mode
in a rotor results in a hybrid mode vibration. In a hybrid mode,
one plate exhibits radial mode behavior and the other plate
exhibits X-mode behavior.
[0009] It would be advantageous to provide an apparatus and method
to prevent the occurrence of hybrid mode behavior in a disc brake
rotor.
SUMMARY OF THE INVENTION
[0010] An aspect present invention provides a rotor for a disc
brake including a pair of friction plates arranged coaxially in a
parallel, spaced-apart relationship and a plurality of vanes
extending between the pair of friction plates. The vanes have a
proximal end, a distal end and a mid-portion extending between the
proximal end and the distal end. The proximal end of a plurality of
the plurality of vanes include a first width, the mid-portion
including a second width, the first width being substantially
greater than the second width.
[0011] Other aspects of the present invention provide a rotor
wherein the first width of half the vanes is substantially greater
than the second width. The first width of the other half of the
vanes can be substantially the same as the second width. The first
width of at least half the vanes can be from about 50 percent
greater than the second width to about twice that of the second
width.
[0012] In another aspect of the invention, a plurality of the
plurality of vanes can include an inverted T-shaped portion
adjacent the proximal end of the vanes. Half of the vanes can
include an inverted T-shaped portion adjacent the proximal end of
the vanes. The inverted T-shaped portion is at least 50% wider than
a width of the mid-portion. The rotor may further include an angled
portion located between each inverted T-shaped portion and the
mid-portion.
[0013] An aspect of the present invention provide a method of
reducing noise in a disc brake rotor including stiffening a
radially inner portion of the brake rotor with a proximal portion
of a plurality of vanes and reducing hybrid vibration modes in an
audible frequency range. The proximal portion of the plurality of
vanes can include an inverted T-shaped portion. Half of the
plurality of vanes can include an inverted T-shaped portion at a
proximal portion. The other half of the plurality of vanes can
include a substantially constant width from a proximal portion to a
distal portion of the vanes.
[0014] Another aspect of the present invention provides a rotor for
a disc brake including means for stiffening a radially inner
portion of the brake rotor with a proximal portion of a plurality
of vanes and means for reducing hybrid vibration modes in an
audible frequency range. The proximal portion of the plurality of
vanes can include an inverted T-shaped portion. Half of the
plurality of vanes can include an inverted T-shaped portion at a
proximal portion. The other half of the plurality of vanes can
include a substantially constant width from a proximal portion to a
distal portion of the vanes.
[0015] The foregoing and other features and advantages of the
invention will become further apparent from the following detailed
description of the presently preferred embodiments, read in
conjunction with the accompanying drawings. The detailed
description and drawings are merely illustrative of the invention
rather than limiting, the scope of the invention being defined by
the appended claims and equivalents thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a perspective view of an embodiment of a
brake rotor of the present invention including inverted T-shaped
vanes;
[0017] FIG. 2 illustrates an alternating arrangement of the vanes
in the brake rotor of FIG. 1;
[0018] FIG. 3 illustrates a prior art rotor exhibiting deformation
generated by a hybrid mode coupling of radial and X-modes of
vibration; and
[0019] FIG. 4 illustrates an embodiment of the present invention
exhibiting less deformation than the rotor of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Referring to FIG. 1 one embodiment of a brake rotor is
generally shown at numeral 110. The brake rotor 110 includes a
central attachment portion 112. An extending portion 114 is
attached adjacent to the periphery 116 of the central attachment
portion 114. A first friction plate 118 (one of a pair of parallel
friction plates) is depicted attached to the central attachment
portion 112 by the extending portion 114. A second friction plate
(not shown), which would be oriented in a parallel, spaced apart
relationship to the first plate 118 is omitted to show the
structure (vanes) therebetween. A plurality of vanes 120, 122 is
provided that extend between the plates and are arranged in a
radial fashion. The vanes 120, 122 are radial members, each having
a proximal end 124, 126 adjacent the extending portion 114 and a
middle span or mid-portion 128, 130 that extends longitudinally in
a radial direction to a distal end 132, 134. The distal end 132,
134 is located adjacent the outer periphery 136 of the friction
plates.
[0021] In one embodiment, a first and a second set of vanes 120,
122 are provided between the plates in an alternating arrangement.
In other words, a first vane 120 is followed by an adjacent second
vane 122, which is followed by a first vane 120 and so on, around
the rotor 110. Each of the first set of vanes 120 has a generally
constant width rectangular shape from proximal end 124 to distal
end 132. Each of the second vanes 122 has an inverted T-shape
configuration. The inverted T-shaped portion 138 is located in the
proximal end 126 of the vane 122. The middle span 130 of the vane
122 is essentially a longitudinally extending rectangular portion.
The vane 122 can include an angled portion 140 between the middle
span 130 and the inverted T-shaped portion 138. The inverted
T-shaped portion 138 of the vane 122 can have a width about 50%
greater than that of the middle span 130 of the vane 122. The
inverted T-shaped portion 138 of each vane 122 can have a width
about twice that of the middle span 130 of the vane 122. Also, the
width of portion 138 can be made from about 50% greater to about
twice that of the middle span 130 of the vane 1220.
[0022] Referring to FIGS. 1 and 2, in an alternating configuration
about the rotor 110 are the first vanes 120 and the second vanes
122. The first vanes 120 can lack the inverted T-shaped
configuration of the proximal portion 126 of the second vanes 122.
The widened portion or inverted T-shaped portion 138 of vanes 122
can add stiffness to the inner diameter or inner periphery 137 of
the rotor 110. This configuration may provide a beneficially
modified pattern of nodal resonance modes.
[0023] Referring to FIG. 3, a depiction of a prior art rotor is
generally shown at 210. The rotor 210 includes a central hat or
disc portion 212. An outer plate 218 is connected to the central
hat portion 212. Inner plate 219 is connected to the outer plate
218 by a plurality of conventional vanes, one of which is shown at
220. In this illustration, the rotor 210 is shown (exaggerated)
exhibiting a hybrid mode deformation including 2.sup.nd radial mode
and 2.sup.nd X-mode deformation.
[0024] Referring to FIG. 4, an embodiment of the present invention
includes a rotor depicted in a similar view as that shown in FIG.
3. The rotor 310 includes a central hat or disc portion 312. An
outer plate 318 is connected to the central hat portion 312. Inner
plate 319 is connected to the outer plate 318 by first plurality of
vanes, one of which is indicated at 320 and a second plurality of
vanes 322. The vanes 322 may include the inverted T-shaped
configuration shown in FIGS. 1 and 2. Compared to the prior art
rotor of FIG. 3, the rotor of the present invention (depicted in
FIG. 4) exhibits less deformation, and thus a lower amplitude or
amount of overall vibration.
[0025] As discussed above, a rotor possesses a number of nodal
diameter and circle modes. Each of the nodal modes generates a
different pattern of resonant rotor vibration. When the n.sup.th
nodal diameter mode (radial) converges or couples near the same
frequency with the one nodal circle mode X-mode), noise is often
produced. The convergence of the radial and X-modes produces a
hybrid mode shape than contains a contribution from each mode
shape. The character of the hybrid mode shape includes one rotor
cheek or plate being a radial mode shape and the other rotor cheek
being a nodal diameter/nodal circle mode shape. The radial mode
content of the hybrid mode receives energy from the tangential
forces of the brake linings. The radial mode couples with the nodal
circle/nodal diameter mode content to produce out-of-plane motion.
This is the mechanism by which the hybrid mode can cause brake
noise or squeal. In operation, the inverted T-shape vane design
increases the stiffness of the nodal circle/nodal diameter modes,
thereby moving their frequencies higher in the spectrum than the
radial modes. The inverted T-shape vanes reduces or eliminates the
hybrid coupling of these modes.
[0026] While the embodiments of the invention disclosed herein are
presently considered to be preferred, various changes and
modifications can be made without departing from the spirit and
scope of the invention. The scope of the invention is indicated in
the appended claims, and all changes that come within the meaning
and range of equivalents are intended to be embraced therein.
* * * * *