U.S. patent application number 10/085743 was filed with the patent office on 2003-08-28 for press-in exciter ring assembly.
Invention is credited to Brown, Matthew Perry, Michalek, John Stanley.
Application Number | 20030160605 10/085743 |
Document ID | / |
Family ID | 27733393 |
Filed Date | 2003-08-28 |
United States Patent
Application |
20030160605 |
Kind Code |
A1 |
Michalek, John Stanley ; et
al. |
August 28, 2003 |
Press-in exciter ring assembly
Abstract
An exciter ring assembly to detect rotational parameters of an
axle within a tube has an exciter ring attached to the axle by an
elastomer insert. The insert provides a frictional interference fit
with the axle. The insert affixes the exciter ring to rotate with
the axle. The elastomer insert is supplied with radially-spaced
axial channels to enable oil flow past the assembly. The outer
member of the assembly is press fit into the axle tube. The outer
member remains stationary with respect to the axle tube. The outer
member restricts the axial movement of the exciter ring and enables
rotation of the exciter ring and provides oil flow across the
exciter ring assembly.
Inventors: |
Michalek, John Stanley;
(Troy, MI) ; Brown, Matthew Perry; (Saginaw,
MI) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
27733393 |
Appl. No.: |
10/085743 |
Filed: |
February 26, 2002 |
Current U.S.
Class: |
324/174 ;
324/207.22 |
Current CPC
Class: |
G01P 3/488 20130101;
B60T 8/329 20130101; G01P 3/443 20130101; G01D 5/202 20130101 |
Class at
Publication: |
324/174 ;
324/207.22 |
International
Class: |
G01P 003/48; G01B
007/30 |
Claims
What is claimed is:
1. A motor vehicle comprising: an axle assembly; a plurality of
sensors adapted to send signals to a controller, said controller
adapted to determine the rotational parameters of an axle within
said axle assembly; and an exciter ring assembly including an
exciter ring coupled to rotate with said axle, said exciter ring
having an annular lip protruding about the circumference of a first
end of said ring, said ring having an aperture to accommodate the
shaft of said axle, said ring having teeth extending axially along
a second end of said ring, said sensor positioned to detect said
teeth of said exciter ring. an outer member concentric to said lip,
adapted to restrain the radially projecting annular surfaces of
either annular end of said lip, said outer member fixed within said
axle assembly.
2. The vehicle of claim 1 wherein an elastomer insert is attached
to the interior surface of said exciter ring and contacting said
axle to restrain the relative rotation between said exciter ring
and said axle.
3. The vehicle of claim 2 wherein said exciter ring includes a
means for promoting oil flow within an axle tube in the region of
said exciter ring assembly including channels within the interior
surface of said elastomer insert to enable oil to pass from a first
axial end of said exciter ring assembly to a second axial end of
said exciter ring assembly.
4. The vehicle of claim 1 wherein said outer member includes
recesses in the circumferential surface, said recesses enable oil
flow past said exciter ring assembly.
5. The vehicle of claim 1 wherein said outer member includes
cutouts in the circumferential surface, said cutouts enable oil
flow past said exciter ring assembly.
6. An axle assembly comprising: an axle tube; an axle passing
through a section of said axle tube; an inner bore within said axle
tube; a sensing means for detecting rotational parameters of said
axle; and an exciter ring assembly press fit into said inner bore
comprising: an exciter ring with an annular lip protruding about
the circumference of a first end of said exciter ring, said exciter
ring having a coaxial bore to accommodate the diameter of said
axle, said exciter ring having axial teeth extending radially along
a second end of said exciter ring, said sensing means positioned to
detect said teeth of said exciter ring; and an outer member
concentric to said lip, adapted to restrain the radially projecting
annular surfaces of either annular end of said lip, said outer
member adapted to an interference fit with said inner bore.
7. The axle assembly of claim 6 wherein an elastomer insert is
attached to the interior surface of said exciter ring and
contacting said axle to restrain the relative rotation between said
exciter ring and said axle.
8. The axle assembly of claim 7 wherein said exciter ring includes
a means for enabling oil flow within said axle tube in the region
of said exciter ring assembly including channels within said
interior surface of said elastomer insert to enable oil to pass
from a first axial end of said exciter ring assembly to a second
axial end of said exciter ring assembly.
9. The axle assembly of claim 6 wherein said outer member includes
recesses in the circumferential surface, said recesses enable oil
flow past said exciter ring assembly.
10. The axle assembly of claim 6 wherein said outer member includes
cutouts in the circumferential surface, said cutouts enable oil
flow past said exciter ring assembly.
11. An exciter ring assembly comprising: an exciter ring with an
annular lip protruding about the circumference of a first end of
said exciter ring, said exciter ring having a coaxial bore to
accommodate the diameter of an axle, said exciter ring having
radial teeth extending axially along a second end of said exciter
ring, said lip having a first radially projecting annular end
surface and a second radially projecting annular end surface; and
an outer member concentric to said lip, said outer member
restraining said first and second annular surfaces of said lip,
said outer member adapted to be restrained relative to rotation of
said axle.
12. The exciter ring assembly of claim 11 wherein an elastomer
insert is attached to the interior surface of said exciter ring and
contacting said axle to restrain the relative rotation between said
exciter ring and said axle.
13. The exciter ring assembly of claim 12 wherein said exciter ring
includes a means for promoting oil flow within an axle tube in the
region of said exciter ring assembly comprising channels within
said interior surface of said elastomer insert to enable oil to
pass from a first axial end of said exciter ring assembly to a
second axial end of said exciter ring assembly.
14. The exciter ring assembly of claim 11 wherein said outer member
includes recesses in the circumferential surface, said recesses
enable oil flow past said exciter ring assembly.
15. The exciter ring assembly of claim 11 wherein said outer member
includes cutouts in the circumferential surface, said cutouts
enable oil flow past said exciter ring assembly.
16. The exciter ring assembly of claim 11 including a spacer
located within said outer member.
17. The exciter ring assembly of claim 16 wherein said spacer
includes outside apertures to enable oil flow.
18. The exciter ring assembly of claim 16 wherein said spacer
includes inside apertures to enable oil flow.
19. An exciter ring comprising an annular lip protruding about the
circumference of a first end of said exciter ring, said exciter
ring having a coaxial bore to accommodate the diameter of an axle,
said exciter ring having radial teeth extending axially along a
second end of said exciter ring, said lip having a first annular
end surface and a second annular end surface and a outer
circumferential surface.
20. The exciter ring of claim 19 wherein said annular lip is
rotatably coupled with an outer member, said outer member
restraining axial movement of said exciter ring, said outer member
having an axial length less than said exciter ring.
21. The exciter ring of claim 19 wherein an elastomer insert is
attached to the interior surface of said exciter ring and
contacting said axle to restrain relative rotation between said
exciter ring and said axle.
22. The exciter ring of claim 21 wherein said exciter ring includes
a means for promoting oil flow within an axle tube in the region of
said exciter ring comprising channels within said elastomer insert
to enable oil to pass from a first end of said exciter ring to a
second end of said exciter ring.
23. The outer member of claim 20 wherein said outer member includes
recesses in said outer circumferential surface, said recesses
enable oil flow past said outer member.
24. The outer member of claim 20 wherein said outer member includes
cutouts in said outer circumferential surface, said cutouts enable
oil flow past said outer member.
25. The exciter ring of claim 20 including a spacer located within
said outer member.
26. The exciter ring of claim 25 wherein said spacer includes
outside apertures to enable oil flow.
27. The exciter ring of claim 25 wherein said spacer includes
inside apertures to enable oil flow.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to speed sensing
devices and specifically to a device to measure the speed of a
motor vehicle axle.
BACKGROUND OF THE INVENTION
[0002] The advent of anti-lock braking systems and traction control
systems have created a need for accurate speed measurement of
individual wheels of a vehicle. Accordingly, there has been an
increase in motor vehicles equipped with speed sensing devices to
measure axle rotation which, in turn, enables measurement of wheel
speed.
[0003] Typically, a ferrous or magnetic exciter ring is installed
to rotate with an axle. A sensor, fixed with respect to axle
rotation, is placed in the vicinity of the teeth of the exciter
ring. When an exciter ring is rotated near a variable reluctance
sensor, the teeth on the exciter ring pass through the magnetic
lines of flux generated by the magnet in the sensor. As the teeth
are passing through the magnetic lines of flux, a voltage is
generated in the coil within the sensor. The magnitude of the
voltage is related to the speed and size of the exciter ring teeth
in addition to design parameters inside the sensor, and inversely
related to the distance between the sensor and the exciter ring
teeth. The exciter ring assembly will also work similarly with an
active (Hall Effect) sensor. The sensor is coupled to a control
system which calculates the angular speed of the axle. The best
sensor design selection is dependent upon the needs of the
controller system. Calculation is carried out with inputs of the
number of teeth sensed per unit of time and the known number of
teeth of the exciter ring. During acceleration or deceleration, the
instantaneous speed of the axle is not directly measurable by these
speed sensing devices due to the finite number of teeth on the
exciter ring. Thus, the accuracy of these devices is limited by the
number of teeth of the exciter ring. A larger diameter exciter ring
that provides more teeth can be used to obtain a more accurate
speed measurement.
[0004] A variety of speed sensing devices have been used in the
art. An example of a known speed sensing device is shown in U.S.
Pat. No. 5,067,350 to Grillo et al. which discloses an annular
exciter ring. Another example is disclosed in U.S. Pat. No.
5,967,669 to Ouchi. Here, a roller bearing unit includes an
integral exciter ring.
[0005] It is known within the art to mount an exciter ring or
target in the differential area of a driven axle. This location can
usually accommodate a larger wheel since the differential housing
within an axle assembly is typically of a larger diameter than the
axle tube. One limitation to a speed sensing device located near
the differential is the inaccuracy of the speed measurement
associated with the elastic twisting of an axle under a torque
loading or torque windup. While an axle is twisting, the actual
wheel speed is not measured.
[0006] Alternatively, it is known to provide a speed sensing device
that is integral with the wheel bearing assembly of an axle. This
location reduces the inaccuracy due to torque windup, and increase
complexity and mass. Additionally, the bearing assembly will have a
higher cost and a different seal assembly may be required. While
the above speed sensing devices may perform adequately for their
intended purposes, a need exists for an improved exciter ring
assembly that is less complex, provides for easier installation,
and results in a more accurate measurement of actual wheel
speed.
SUMMARY OF THE INVENTION
[0007] In view of the above, the present invention is directed to
an exciter ring assembly that can be interference or press fit into
an axle tube. An exciter ring is provided with teeth and is affixed
to an axle. A sensor is fixed to the axle tube and located close to
the teeth of the exciter ring. As the axle rotates, the sensor
detects the movement of the exciter ring teeth. The sensitivity of
the assembly is inversely related to the distance between the
sensor and the teeth (typically a few millimeters or less). The
exciter ring rotates in relation to an outer member that
encompasses an integral lip of the ring. The outer member supplies
the outside diameter for a press fit with an inside diameter of the
axle tube. The axle tube can be provided with a bore inboard of the
wheel bearing bore to accommodate this press fit. The outer member
is constructed of stamped metal or similar construction capable of
withstanding the press fit. Flutes are provided in the
circumference of the outer member to promote oil flow past the
exciter ring assembly and lubricate the wheel bearing. A spacer is
located within the outer member and adjacent to the lip of the
exciter ring to provide the correct spacing for the final assembly.
The spacer helps to prevent noise in the assembly Additionally, the
spacer is provided with cut-outs that enable oil flow past the
exciter ring assembly. The press fit installation of the exciter
ring assembly simplifies assembly since no further alignment or
positioning of the exciter ring is necessary to ensure that the
sensor, when installed, is within the required proximity to the
teeth of the exciter ring.
[0008] The exciter ring assembly is press fit into the axle tube
between the bearings that support the axle. The exciter ring
assembly can be installed into the axle tube during manufacture of
the axle assembly prior to installation of the wheel bearing. This
location of the exciter ring assembly, near the wheel bearing, will
ease axle alignment with the exciter ring bore during axle
installation. Also the location reduces speed sensing inaccuracies
due to torque windup. The diameter of the exciter ring can be
larger than typical wheel bearing speed sensing rings and thus
provide for more accurate speed measurement.
[0009] A further benefit to locating the exciter ring near the
wheel bearing is derived from the lower amount of axle deflection
near the bearings than at a location further from the bearings.
Lower axle deflection reduces the gap variation distance between
the sensor and teeth which, in turn, provides improved sensitivity.
Lower axle deflection also reduces the maximum distance between the
sensor and teeth which also provides improved sensitivity.
[0010] Further areas of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0012] FIG. 1 is a schematic representation of an exemplary vehicle
having the present invention incorporated therein;
[0013] FIG. 2 is a sectional view of the axle assembly taken along
line 2-2 of FIG. 1 incorporating the present invention;
[0014] FIG. 3 is a sectional view of the exciter ring assembly
taken along line 3-3 of FIG. 2 showing the ring teeth and elastomer
insert flutes;
[0015] FIG. 4 is a sectional view of the exciter ring assembly
along the axis of the axle showing the exciter ring lip;
[0016] FIG. 5 is a sectional view of the outer member of the
exciter ring assembly taken perpendicular to the axis of the
assembly showing recesses for oil flow;
[0017] FIG. 6 is an alternate embodiment of the outer member of the
exciter ring assembly showing cutouts for oil flow;
[0018] FIG. 7 a view of the spacer utilized within the exciter ring
assembly taken perpendicular to the axis of the assembly; and
[0019] FIG. 8 an alternate embodiment of the spacer utilized within
the exciter ring assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] The following description of the preferred embodiment(s) is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses.
[0021] In general, the present invention is directed to a speed
sensing device which is operably installed within an axle tube.
Referring to FIGS. 1 and 2, a four wheel drive vehicle 10 is
schematically shown with axle assembly 12. Axle assembly 12
interconnects wheels 14. A controller 16 receives data from sensors
18. This data relates to the rotational parameters of axle 20.
Sensors 18 are connected to axle assembly 12. Controller 16 is
adapted to supply data to anti-lock braking systems, traction
control systems, adaptive four-wheel drive systems or the like.
Axle 20 is rotatably supported in axle tube 22 by differential
bearing 24 and wheel bearing 26. Sensor 18 is mounted to axle tube
22 in close proximity to exciter ring 28. In the embodiment shown,
exciter ring 28 is provided with an elastomer insert 30 that is
sized for an interference fit with axle 20. Thus provided, exciter
ring 28 is coupled to rotate with axle 20.
[0022] With continued reference to FIG. 2, exciter ring assembly 32
includes exciter ring 28 which is provided with lip 34. Exciter
ring assembly 32 also includes outer member 36. The circumference
of lip 34 fits within outer member 36 and is rotatable therewith.
Outer member 36 is press fit into exciter ring axle bore 38 of axle
tube 22. Wheel bearing 26 is fitted into wheel bearing bore 40 of
axle tube 22.
[0023] With reference to FIG. 3, exciter ring assembly 32 is shown
in cross section perpendicular to the axis of axle 20. Exciter ring
28 has an inside surface 42 that is attached to elastomer insert
30. Preferably, the insert is of an elastomeric material. Elastomer
insert 30 has channels 44 that are provided to enable oil flow
between elastomer insert 30 and axle 20. An interior surface 46 of
elastomer insert 30 is interference fit with axle 20 to ensure that
exciter ring 28 rotates with axle 20. In the embodiment shown, oil
channels 44 are formed in interior surface 46 of elastomer insert
30 to form interior surface 48 of elastomer insert 30.
[0024] With continued reference to FIG. 3, exciter ring 28 has
teeth 50. Sensor 18, also shown in FIG. 2, detects the presence or
absence of teeth 50 as exciter ring 28 rotates around the axis of
axle 20. In the preferred embodiment, fifty-five teeth 50 are
equally spaced around the circumference of exciter ring 28. As is
known, sensor 18 can be operably connected to a controller 16 to
calculate the rotational parameters of exciter ring 28. Rotational
parameters include wheel speed and acceleration. These rotational
parameters can be used as input to an anti-locking brake system,
traction control system, torque modulating four-wheel drive system
or other systems that require vehicle or wheel speed. An exemplary
control system is described in U.S. Pat. No. 5,332,060, the
specification and drawings therein are expressly incorporated by
reference.
[0025] When the exciter ring 28 is rotated near the variable
reluctance sensor 18, the teeth 50 on the exciter ring 28 pass
through magnetic lines of flux generated by a magnet in the sensor
18. As the teeth 50 are passed through the magnetic lines of flux,
a voltage is generated in a coil within the sensor 18. The
magnitude of the voltage is related to the speed and size of the
exciter ring teeth 50 in addition to design parameters within the
sensor 18. A larger diameter exciter ring provides more teeth which
in turn provides increased accuracy in the measurement of
rotational parameters. In addition, a larger diameter exciter ring
enables larger teeth and faster peripheral speed both of which
improve sensitivity of the system and enable increased
manufacturing tolerances and reduced cost. The magnitude of the
voltage is inversely related to the distance between the sensor 18
and the exciter ring teeth 50. The lower the deflection of the
shaft, the less gap variation and the less the maximum gap, both of
which provide for improved sensitivity. The exciter ring assembly
will also work similarly with an active (Hall Effect) sensor.
[0026] With reference to FIG. 4, exciter ring assembly 32 is shown
in cross section along the axis of axle 20. Exciter ring 28 is
shown with lip 34 within outer member 36. Spacer 52 is shown
adjacent to a first annular surface 54 of lip 34. Outer member 36
is shown to enclose lip 34 of exciter ring 28 and spacer 52. Outer
member 36 enables rotation of exciter ring 28 about the axis of
axle 20. Exciter ring 28 is limited in its axial movement with
respect to sensor 18 during installation due to the interference
between outer member 36 and first and second radially projecting
annular surfaces 54, 56 of lip 34.
[0027] FIG. 5 shows the preferred embodiment of outer member 36
with circumferential recesses 58 formed along the axial length of
outer member 34. The recesses 58 enable oil flow past the exciter
ring assembly 30. FIG. 6 shows an alternate embodiment of outer
member 36 with circumferential cutouts 60 to permit oil flow past
the exciter ring assembly 32.
[0028] FIG. 7 shows the preferred embodiment of spacer 52. Outside
apertures 62 enable oil flow through the exciter ring assembly 30.
FIG. 8 shows an alternate embodiment of spacer 52. Here, inside
apertures 62 enable oil flow through exciter ring assembly 32.
Alternatively, a coating may be added to the lip to act as a
spacer. Here grooves may be present to enhance oil flow.
Additionally, the coating, like the spacer, acts to reduce
noise.
[0029] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the gist of
the invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *