Note: Descriptions are shown in the official language in which they were submitted.
~LC)S 3 3 4~3
MOUNTING DEVICE FOR CYLINDRICAL
MAGNETIC SENSOR
:
Background of the Invention
Field of the Invention. This invention relates to a
cylindrical wheel speed sensor and, more specifically, to a mounting
device for such a sensor which enables the sensor to be utilized in
a variety of whee1 configurations while maintaining accurate
positioning thereof for reliable operation.
Description of the Prior Art. Modern anti-lock vehicle brake
control systems operate in response to electrical signals indicative
of the angular velocity of one or more of the vehicle wheels. Usually ~ ;
these signals are derived from an electromagnetic sensor, including a ~-
magnet carried by a stationary portion of the vehicle such as the axle
housing and a toothed or notched metal ring which rotates with the
wheel opposite the magnet. As the ring teeth pass the magnetic sensor
device, the resulting variations in flux prodùce a voltage, the frequency
of which is a function of the angular velocity of the wheel and number
of teeth in the ring.
~: : : T produce the required voltage level of the velocity signal,
~ ~ the sensor and ring must be accurately located with respect to each
other during initial assembly and must remain in a preselected
re1ationship even af~er extended operation in which the components are
subjected to road shocks and constant vibration. It is also essential
that installation of the sensor assembly be accomplished in a manner
adaptable to mass production methods to minimize the need for skilled
technicians and elaborate installation techniques.
Further, to satisfy an ever increasing demand for brake control
systems, it has become necessary to provide sensor-rotor systems to a
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variety of existing wheel configurations. Consequently, to simplify ;
and standardize the sensors, a generally cylindrical housing has been
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provided which has overall dimensions to accommodate installation at
various locations as desired for the particular wheel assembly. The
means for mounting this sensor must ;nsure that the above mentioned
relationships can be obtained during installation and retained during
vehicle operation.
There have heretofore been utilized wheel speed sensors, such
as those disclosed in U. S. Patent No. 3 9 769,534, 3,772,548, 3,772,549,
and 3~77~,061, in an effort to provide overall configurations which
satisfy some of the above stated requ;rements.
o Summary of_the Invention
Accordingly, it is an o~ject of this invention to provide a
novel magnetic sensor mounting device in which the sensor can be readily
adjusted to a predetermined precise relationship with the rotor during
initial installation and maintained in that predetermined relationship
during operation of the vehicle.
It is another object of the invention to provide a magnetic
sensor mounting device of the type described which is inexpensive to
produce and simple to install.
It is a further object of the invention to provide a magnetic
sensor mounting device of the type described which may be readily `
adapted for use in a variety of existing wheel configurations. ;
To accomplish these and other objects of the invention, a
preferred embodiment thereof includes a magnetic sensor mounting device
for a wheel speed sensor assembly. The assembly is capable oF being
installed in association with a wheel rotatably mounted on an axle.
The wheel speed sensor assembly includes an annular rotor means coaxially
aligned with and connected to the wheel for rotation therewith and a
generally cylindrical magnetic sensor alignable with a sector of the
annular rotor means. The preferred magnetic sensor mounting device ~
includes a support structure for the magnetic sensor which is adapted ~;
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to be fixedly mounted on the axle assembly in alignment with the
annular rotor means. A resiliently deformable sleeve member has a
generally cylindrical opening to closely receive the magnetic sensor
therein. The sleeve member has an outer surface at a first end thereof
which is gradually tapered inwardly. The support structure includes
a means for selectively applying an axial force to the sleeve member
when the magnetic sensor is positioned at a predetermined actual
location therein to inwardly deform the sleeve member against the
magnetic sensor to produce frictional contact therebetween.
Consequently, the application of the actual force will maintain the
magnetic sensor at the predetermined axial location.
Brief Description of _ e Drawings
Figure 1 is a fragmentary view of a wheel assembly, partly in
sections, including the preferred embodiment and showing various features
of the invention.
Figure 2 is a fragmentary view of another wheel assembly,
partly in sections, including an alternative embodiment of the invention.
Figure 3 is a sectional top view of another alternative
embodiment of the invention.
Detailed Description of the PreFerred Embod ments
As seen in Figure 1, by a fragmentary view thereof, a Front
axle assembly 2 includes a steering spindle 4. A wheel 6 is mounted for
rotation about the spindle 4 to include a wheel bearing assembly 8,
a bearing seal 10 and an oil slinger 12 in a general configuration which
is well known in the art. A rotor 14 is mounted to the wheel 6 by a
rotor support frame 16 so that the rotor 14 is coaxially aligned with ~ -
the wheel. The rotor 14 is annular and includes a surface 18 which is
toothed or notched to provide the desired signal as described hereinabove.
A magnetic sensor 20 which is adapted for alignment with the
surface 18 is generally cylindrical in shape. In the preferred
installation of Figure 1, the sensor 20 is to be fixedly mounted to the
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axial assembly in alignment with the surface 18 of rotor 14 For
detection of the relative rotation therebetween. The general alignment
can be best seen at 20'.
To provide support for the sensor 20, a wheel backing plate
22 which is fixedly mounted on the spindle 4 is provided in the t
preferred embodiment with a pair of bolt holes 24 and a sensor receiving
cavity 26. A support housing 28 is adapted to be secured to the wheel
backing plate 22 by a pair of nut and bolt assemblies 30 The support
housing 28 includes a central cavity 32 which is aligned with the
sensor receiving cavity 26 of the backing plate 22. The central cavity
32 of the housing 28 is threaded to receive an adjusting nut 34. The
adjusting nut 34 also includes a centrally located cavity 36 so that the
sensor 20 may be received within the aligned cavities 26, 32 and 36.
A generally tubular sleeve member 38 is adapted to be received
within the central cavity 32 between a shoulder 40 of the cavity 32
and the adjusting nut 34. An interior passageway 42 of the sleeve ~
member 38 is generally shaped and dimensioned to closely encircle the ;
sensor 20. The sleeve member 38 is formed of a resiliently deformable
material having the tendency to be noncompress;ble. A plastic material
has, for example, been found to work satisfactorily to insure that the
sleeve member 38 may be inwardly deformed without significant compression
in the axial direction.
Characteristically, at a first end 44 of the sleeve member ;~
38, the outer surface 46 of the sleeve member 38 is gradually tapered
inward1y. Further, the centrally located cavity 36 of the adjusting
nut 34 is at its inward end 48 generally conical to mate with the first
end 44 oF the sleeve member 38. It can be seen from Figure 1 that with
the sensor 20 positioned within the support housing 28, the application
of an axial force on the sleeve member 38 by adjusting rotation of the
adjusting nut 34 will tend to deform the first end 44 o-F the sleeve
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member 38 inwardly to make gripping, frictional contac~ with the sensor
20. The force created by the cooperation of the sleeve member 38 and
the adjusting nut 34 has been found to effectively prevent any undesired
axial movement of the sensor 20. Since the sleeve member 38 is generally
noncompressible, the application of axial force by the adjusting nut 34
presses the second end 50 against the shoulder 40 of the central cavity
32. However, since the sleeve member 38 is generally noncompressible,
the axial force is transferred through resulting forces acting on the
tapered outer surface 46 to cause the first end 44 to be generaly
deformed inwardly against the sensor 20.
An understanding of the installation requirements for the
mounting device of the present invention will demonstrate other
advantages which the configuration of the preferred embodiment provides.
With the rotor 14 'installed on the wheel 6 and the support housing 28
generally installed on the wheel backing plate 22, it is essential to
properly, axially position the sensor 20 with respect to the rotor 14.
Although not shown in Figure 1, the sensor 20 includes two sensor
elements which may be circumferentially aligned with the surface 18
of the rotor 14. Accordingly, one section of the generally cylindrical
magnetic sensor 20 is flat as is indicated at 52 and 52'. By providing
a matching flat sectlon on the cavity 26 and/or the cavity 32, the flat
section 52 of the sensor 20 insures proper alignment and orientation
thereof. With the adjusting nut 34 loose, th'e sensor 20 can be received
within the sleeve member 38 and inwardly positioned against the surface
18 of the rotor 14. Hand tightening the adjusting nut 34 then allows a
limited deformation of the end 44 to generally restrict actual movement
of the sensor 20 without preventing it. The wheel 6 is then rotated to
cause the surface 1~ of the rotor 14 to act against the sensor 20 to
position it to the right as may be necessary because of slight rotor
30 ~ misalignment or imperfections. Consequently, the sensor 20 will be
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positioned at a location adjacent the surface 18 without continuous
contact therewith or an application of a force therebetween. Tightening
of the adjusting nut 34 will generate sufficient frictional contact
between the sleeve member 38 and the magnetic sensor 20 to prevent
axial movement from this desired location.
It should be noted that the tapered con~igurat;on of the
preferred sleeve member particularly satisfies these installation
requirements. Generally, the sleeve member 38 acts during the
installation as a one-way clutch on the sensor 20. When a moderate
force is applied to the first end 44, the smoo-th surface of the interior
passageway 42 allows some movement to the right. However, the leading
edge 56 of the first end 44 will have a tendency to grip the sensor
20 to prevent its accidental movement to the left during adjusting nut
tightening.
Turning to Figure 2, it can be seen that a different front axle
assembly 58 includes a steering spindle 60. Similarly, a wheel 62
with an appropriate wheel bearing assembly 64 and bearing seal 66 is
again installed on the spindle 60. There is also associated with the ~-~
, . :wheel 62 a rotor 68. Although the mounting means is not shown, the
rotor 68 is again mounted coaxially with the wheel 62 for rotation
therewith.
A generally cylindrical maynetic sensor 70 is provided for this
alternative installation but includes, for manufacturing reasons, a
flat surface 72 which extends throughout its length. For ~his alternative
installation, the steering knuckle structure 74 is provided with a hole
76 therethrough for receiving the sensor 70 in a position for alignment
with the rotor 68. For added sensor support, installed alignment through
a brake spider 78 is provided. The brake spider 78 is secured to the
steering knuckle struc~ure 74 and includes an opening 80 therethrough
which is aligned with the hole 76.
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To restrict axial movements of the sensor 70, a resiliently
deformable sleeve member 82 is again employed and includes a first
end 84 which is tapered. When the sleeve member 82 is positioned about
the sensor 70, a second end 86 thereof is positioned against the surface
88 of the steering knuckle structure 74. To provide the axial force
needed to deform the first end 84 of the sleeve member 82 in this
configuration, a preformed cantilever spring member 90 is provided.
The spring member 90 is stamped and formed of sheet spring metal to
include a first end 92 having a hole threrethrough so that it may be
anchored to the steering knuckle structure 74 by a bolt 94 which is
received within a threaded hole 96 in the structure 74. A hole is
punched in the other end 98 of the spring member 90 so that an interior
flange 100 may be formed. The interior flange 100 is generally tapered
and dimensioned to mate with the tapered first end 84 of the sleeve
member 82. The location of the anchored end 92 of the spring member 90
and the general dimensions of the sleeve member 82 and the spring member -
90 insure that when the bolt 94 is Fu11y received within the threaded
hole 96, the spring member 90 will be sufficiently deformed to generate
a biasing force at the interior flange 100 for proper deformation of
the first end 84 of the sleeve member 82.
Installation of the sensor 70 is similar to that of the sensor
20 described hereinabove. When initially inserted through the steering
knuckle structure 74, the orientation of the sensor 70 is obtained,
however, by positioning the flat surface 72 against a circumferential -
surface 102 of the wheel 62. When the end of the sensor 70 is against
the rotor 68, the bolt 94 is tightened to provide some restriction to
sensor movement by the first end 84 oF the sleeve member 82. Rotation
of the wheel 62 again positions the sensor 70. Continued tightening of
the bolt 94 generates sufficient force through the interior flange 100
and the first end 84 of the sleeve member 82 to prevent axial movement
of the sensor 70 from its desired position.
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In -this confiauration of Fiqure 2, it can be seen that the
present invention will accommodate sensors which do not have a circular
cross-section at the first end 84 of the sleeve member 82. Althouah a
sleeve member of the type utilized in the embodiment of Figure 1 miaht
also be utilized in that of Fiaure 2 to provide sufficient retention ~;
force, the sleeve member 82 has been altered to show an alternate means
for accommodating sensors which do not have a circular cross-section.
As can be seen at 104, the ~irst end 84 of the sleeve member 82 has
been formed into extended sections which are divided by slots so that
they may be individually deformed inwardly to retain a sensor. The
sleeve member 82 therefore is presented, by way of example, as a means
whereby a sensor which is only generally cylindrical may be retained by
use of the present invention. It should also be clear that if one
wishes to simply accommodate sensors having different diameters, for
example, those made with larger tolerances to decrease manufactur;na
costs, a single slot may be used. The single slot would beneficially
be located at the first end 84 but might also extend lonaitudinally for
the entire length of the sleeve member.
To further demonstrate the versatility and adaptability
provided by the present invention, the disclosure provided in U.S.
Patent No. 3,772,548 should be con`sidered. U.S. Patent No. 3,772,548
discloses a sensor and wheel configuration which includes a sensor module
48 which is rigidly mounted on a suitable bracket assembly 60 in alignment
with a rotating rotor ring 42. The disclosure includes an explanation of `
how the sensor module is positioned outwardly toward the wheel so that the
rotor ring 42 wiil make contact with the sensor module 48 when the wheel
is installed. The sensor module 48 is moved inwardly by the rotor ring
42 to provide the desired position for operation. Accordin~ly, the
sensor module 48 ;s inaccessible a-fter the wheel is installed so that
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adjustments must be made automatically rather than by the me~hods
described hereinabove.
However, it has been found that the cylindrical sensors and
the mounting device of the present invention can be utilized in the
wheel-sensor configuration of U. S. Patent No. 3,772~5~8 while providing
an additional important feature. Because of the limited space
requirements for the cylindrical sensor and the mounting device of
the present invention, it has been found that ~wo sensors could be
utilized to replace the one sensor which was previously utilized for
anti-skid control alone. There is presently being expressed an increased
interest in electronic speedometers and the second sensor of this
improved configuration prov;des a separate signal for this added purpose.
As seen ;n Figure 3, an improved sensor module 106 is provided
and includes a support structure 108 which retains a pair of magnetic
sensors 110 therein. The support structure 108 ;ncludes a pa;r of
mounting brackets 112 which allows the sensor module 106 to be
substituted for the sensor module 48 of U. S. Patent No. 3,772,548 by
being secured to the suitable bracket assembly 60 disclosed therein.
Accordingly, the sensors 110 would be aligned wi~h the rotor r;ng to ;
provide the desired signals for anti-sk;d control and speed ;ndicat;on.
A sleeve member 114 ;s sim;lar to the s1eeve member 38
described hereinabo~e to include a tapered end 116. A sleeve member 114
closely encircles each sensor 110 so that they may be received within
a tapered opening 118 of the support structure 108. A spring washer
120 is then positioned around the sensor 110 to make contact with the
other end 122 oP the sleeve member 114. A cover plate 124 includes a
pair of holes 126 therethrough for receiving the sensors 110 and is
secured by a bolt 128 to the support structure 108 at a ~hreaded hole
130 therein. The dimensions of the support structure 108, sleeve member
114, and the cover plate 124 are such that the spring washer 120 will
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apply an axial force to the sleeve member 114 when the bolt 128 ;s
fully received within the hole 130.
When the sensor module 106 is mounted for initial
installation, each magnetic sensor 110 is positioned forward of the
rotor line 132 prior to the tightening of bolt 128. With each sensor
110 so positioned, bolt 128 can be tightened to generally generate an ;~
axial force through the spring washers 120 which will cause the
tapered ends 116 to be inwardly deformed by the tapered opening 118 for
retention of the sensors 110. The bolt 128 must be fully tightened to
generate the axial force for sensor retention at initial installation
because the location of the sensor module 106 prevents access thereto
after the wheel has been installed.
There is the feature of this embodiment which is not found ;~
in the embodiments herein described above. It can be seen, for example,
that in configuration of Figure 3 the tapered end 116 is positioned
toward the rotor. From the descriptions provided hereinabove, it would
appear that the leading edge of the tapered end 116 would prevent any
axial movement of the sensor 110 in a direction generally away from the
rotor line 132. However, since the spring washers 120 are provided to
basically generate the axial force, it can be seen that axial movement
of the magnetic sensor in a direction away from the wheel is allowed.
As the wheel is installed, the rotor acts on each sensor 110 to cause
it to move lnwardly. The initial application o~ force to the sensor 110
is resisted by the friction created at the leading edge at the tapered
end 116. However, this force acts on the entire sleeve member 114
causing lt to depress the spring washer 1~0 thereby releasing the
tapered end 116 from the tapered opening 118 to prevent continued ;
de-formation of the tapered end 116. Without continued deformation of
the tapered end 116, the friction forces tending to restrict axial
movement of the sensor 110 are removed and the sensors 110 are allowed
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to be positioned as shown in F;gure 3 along the line 132 which
represents final rotor position. At this desired position, the sensors
110 are again acted upon by the spring washer 120 and the sleeve
member 114 to prevent axial movement toward the rotor. ~lovement
toward the rotor can only tend to further insert the tapered end 116
into the tapered opening 118 to thereby increase the inward deformation
of the end 116 toward the sensor 110 to increase frictional contact
therebetween.
It can be seen therefore that the configuration shown in
Figure 3 provides a one-way clutch for the magnetic sensors 110 when
the retaining force is fully applied. This feature is different from
that discussed hereinabove wherein the one-way clutch feature is
provided only when the retaining axial force is only partially applied. ;
The method of retention is different from the embodiments shown because
of the different requirements for initial installation. The actual
difference in retention is accomplished by the fact that the sensor
module 106 includes a spring washer at the rearward end 122 of the
sleeve member 11~ to allow the sleeve member 114 to move axially within
the support structure 108 for selective applica~ion of retaining force
to the sensors 110.
While there has been shown and described hereinabove various
preferred embodiments of the invention, it will now be obvious to
those skilled in the art that changes and modificat;ons may be made
therein without departing from the claimed invention.
