Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2000-09-07
2003-06-10
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
Reexamination Certificate
active
06575637
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an automotive brake rotor and a wheel bearing assembly.
Various kinds of wheel bearing assemblies are known including ones for driving wheels and ones for non-driving wheels.
FIG. 27
shows a wheel bearing assembly for a driving wheel. It comprises an outer member
3
having two raceways
3
a
,
3
b
formed on its inner peripheral surface, an inner member
1
having two raceways
1
a
,
1
b
opposite the respective raceways
3
a
,
3
b
, and rolling elements or balls
8
disposed between the raceways
3
a
,
3
b
on the outer member
3
and the raceways
1
a
,
1
b
on the inner member
1
in two rows. The inner member
1
has a flange
2
adapted to be secured to a wheel and is formed with a splined bore
9
into which is inserted a drive shaft.
A brake rotor
5
is positioned by bolts
18
to the outer side
2
a
of the flange
2
and secured between the outer side
2
a
and the wheel hub by bolts
7
. Any runout of the brake rotor
5
can cause vibrations or squeal during braking, or uneven wear of the brake rotor and/or brake pad.
Brake rotors and wheel bearings are usually delivered to a car manufacturer, who assemble them together. It has been an ordinary practice to adjust to minimize runout of the brake rotor
5
when or after assembling the rotor and the wheel bearing, by e.g. adjusting the angular position of the mounting bolts
7
. But such work is troublesome and inefficient.
An object of the invention is to provide a brake rotor and a wheel bearing assembly that are reliable and need no runout adjustment at a car manufacturer.
SUMMARY OF THE INVENTION
According to the invention, a brake rotor is provided which is mounted to a rotary member of a wheel bearing assembly for rotatably supporting a wheel on a vehicle body by means of double-row rolling elements. The maximum runout variation of a mounting surface on the side of the brake rotor abutting the rotary member is restricted within a predetermined value.
By restricting the maximum runout variation of the mounting surface on the side of the brake rotor abutting the rotary member within a predetermined value, runout of the brake rotor mounted to the rotary member is suppressed low within a desired range and troublesome runout adjustment after assembling has become unnecessary.
By restricting the maximum runout variation of a back side of the mounting surface to which a wheel hub is mounted within a predetermined value, it is possible to suppress the runout of the brake rotor.
By restricting it to 50 &mgr;m or less, the brake rotor will be reliable and will not require any runout adjustment after assembly.
By restricting the runout variation per cycle of the mounting surface or its back side within a predetermined value, it is possible to smoothen the runout of the brake rotor.
According to the invention, the runout variation per cycle of the mounting surface should be restricted to 30 &mgr;m or less.
According to the invention, the maximum difference between the peak values of crests or the maximum difference between the peak values of troughs in each runout cycle of the mounting surface or its back side should be restricted within a predetermined value. Thereby it is possible to suppress the runout of the brake rotor to a lower value. The predetermined value should be not more than 30 &mgr;m.
According to the invention, it is preferable that the frequency per rotation of runout of the mounting surface be a multiple of the number of wheel mounting bolts or the number of the mounting bolts be a multiple of the frequency. Thereby it is possible to make uniform the deformation of the brake rotor due to tightening force applied to the mounting bolt and suppress the runout of the brake rotor resulting from the deformation of the brake rotor.
According to the invention, there is provided a wheel bearing assembly comprising an outer member having two raceways on its inner surface, an inner member having two raceways on its outer surface, opposite to the respective raceways on the outer member, and two rows of rolling elements mounted between the opposed raceways, wherein a wheel mounting flange is formed on one of the outer member and the inner member, wherein one side of the wheel mounting flange is a mounting surface for a brake rotor, characterized in that the maximum runout variation of the brake rotor mounting surface is restricted within a predetermined value.
By restricting the maximum variation of runout of the brake rotor mounting surface of the wheel mounting flange within a predetermined value, it is possible to suppress runout of the brake rotor without carrying out troublesome runout adjustment after assembling.
According to the invention, the predetermined value should be 50 &mgr;m and preferably 30 &mgr;m.
By restricting the runout variation per cycle of the brake rotor mounting surface within a predetermined value, it is possible to smoothen the runout of the braking surface of the brake rotor.
By restricting the maximum difference between the peak values of crests or the maximum difference between the peak values of troughs in each cycle of runout of the brake rotor mounting surface within a predetermined value, it is possible to suppress the runout of the braking surface of the brake rotor.
It is preferable that the frequency per rotation of runout of the brake rotor mounting surface be a multiple of the number of wheel mounting bolts or the number of the wheel mounting bolts be a multiple of the frequency. Thereby it is possible to make uniform the deformation of the brake rotor due to tightening force applied to the mounting bolt and suppress the runout of the brake rotor resulting from the deformation of the brake rotor.
Also, in the arrangement in which the brake rotor mounting surface is the outer side of the wheel mounting flange, by inclining this side outwardly toward the tip of the wheel mounting flange, when the brake rotor and the wheel hub are superposed and tightened by wheel mounting bolts, the wheel mounting flange is resiliently deformed, so that the outer peripheral portion of the brake rotor mounting surface is pressed hard against the brake rotor. Thus, the brake rotor is stably supported by the outer peripheral portion. In this case too, by also restricting the maximum runout variation of the brake rotor mounting surface within a predetermined value, it is possible to suppress runout of the braking surface during rotation of the brake rotor.
The inclination angle of the brake rotor mounting surface is preferably 20′ or less. If this angle is greater than needed, even if the wheel mounting flange is resiliently deformed, the inner peripheral portion of the brake rotor may become out of contact with the brake rotor mounting surface, so that the mounting of the brake rotor becomes unstable. The upper limit of the inclination angle that will not become unstable is determined at 20′.
By setting the degree of flatness and circumferential flatness of the outer peripheral portion of the brake rotor mounting surface at 30 &mgr;m or less, it is possible to suppress runout of the braking surface during rotation of the brake rotor pressed hard against the outer peripheral portion.
As shown in
FIG. 25A
, the circumferential flatness is measured as described below. The wheel mounting flange
2
is rotated with the probe of a measuring device such as a dial gauge
22
in contact with the outer peripheral portion of the side
2
a
, which is the brake rotor mounting surface of the wheel mounting flange
2
.
FIG. 25B
is a graph showing undulation picked up by the probe of the dial gauge. The circumferential flatness is the minimum distance 6 between two parallel lines L
1
and L
2
between which the undulation is contained.
The wheel mounting flange may be formed integrally with the outer member or the inner member.
By mounting the above-mentioned brake rotor with less runout on the brake rotor mounting surface, the runout of the braking surface of the brake rotor during rotation can be suppressed.
According to the present
Azuma Kazuhiro
Fukushima Shigeaki
Kinpara Naoshi
Niki Motoharu
Ohtsuki Hisashi
Footland Lenard A.
NTN Corporation
Wenderoth , Lind & Ponack, L.L.P.
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