U.S. patent application number 10/959084 was filed with the patent office on 2005-04-07 for cylindrical cover-attached encoder apparatus.
Invention is credited to Shiotsuka, Ai, Yamaguchi, Yoshihiko.
Application Number | 20050073444 10/959084 |
Document ID | / |
Family ID | 34386425 |
Filed Date | 2005-04-07 |
United States Patent
Application |
20050073444 |
Kind Code |
A1 |
Shiotsuka, Ai ; et
al. |
April 7, 2005 |
Cylindrical cover-attached encoder apparatus
Abstract
A cylindrical cover-attached encoder apparatus, including a
magnetic metal-based body having a cylindrical shape, a magnetic
rubber-based encoder having a cylindrical shape and formed around
the outer peripheral surface of said magnetic metal-based
cylindrical body, and a nonmagnetic material-based cover having a
cylindrical shape and adapted to be mounted on said magnetic
rubber-based encoder for covering the outer peripheral surface of
the cylindrical portion of said magnetic rubber-based encoder.
Inventors: |
Shiotsuka, Ai; (Okayama,
JP) ; Yamaguchi, Yoshihiko; (Okayama, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
34386425 |
Appl. No.: |
10/959084 |
Filed: |
October 7, 2004 |
Current U.S.
Class: |
341/15 |
Current CPC
Class: |
G01D 5/14 20130101; G01P
3/487 20130101; G01D 5/145 20130101; G01P 3/443 20130101; F16C
41/007 20130101; G01D 5/00 20130101; G01D 2205/80 20210501 |
Class at
Publication: |
341/015 |
International
Class: |
H03M 001/22 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 7, 2003 |
JP |
2003-348172 |
Claims
1. A cylindrical cover-attached encoder apparatus, including: a
magnetic metal-based body having a cylindrical shape; a magnetic
rubber-based encoder having a cylindrical shape and formed around
the outer peripheral surface of said magnetic metal-based
cylindrical body; and a nonmagnetic material-based cover having a
cylindrical shape and adapted to be mounted on said magnetic
rubber-based encoder for covering the outer peripheral surface of
the cylindrical portion of said magnetic rubber-based encoder.
2. The cylindrical cover-attached encoder apparatus as defined in
claim 1, wherein the magnetic metal-based cylindrical body is
formed by using any of the sintered metals.
3. The cylindrical cover-attached encoder apparatus as defined in
claim 1, wherein the magnetic metal-based cylindrical body is
formed by using any of the steel materials.
4. The cylindrical cover-attached encoder apparatus as defined in
claim 1, wherein one end of the cylindrical portion of said
nonmagnetic material-based cover which covers the outer peripheral
surface of the magnetic rubber-based encoder is extending beyond
the cylindrical portion of the magnetic rubber-based encoder in the
axial direction of the magnetic metal-based cylindrical body and
wherein the nonmagnetic material-based cover is attached to the
magnetic rubber-based encoder by swaging the one end of the cover
which extending beyond the cylindrical portion of the magnetic
rubber-based encoder.
5. The cylindrical cover-attached encoder apparatus as defined in
claim 2, wherein one end of the cylindrical portion of said
nonmagnetic material-based cover which covers the outer peripheral
surface of the magnetic rubber-based encoder is extending beyond
the cylindrical portion of the magnetic rubber-based encoder in the
axial direction of the magnetic metal-based cylindrical body and
wherein the nonmagnetic material-based cover is attached to the
magnetic rubber-based encoder by swaging the one end of the cover
which extending beyond the cylindrical portion of the magnetic
rubber-based encoder.
6. The cylindrical cover-attached encoder apparatus as defined in
claim 3, wherein one end of the cylindrical portion of said
nonmagnetic material-based cover which covers the outer peripheral
surface of the magnetic rubber-based encoder is extending beyond
the cylindrical portion of the magnetic rubber-based encoder in the
axial direction of the magnetic metal-based cylindrical body and
wherein the nonmagnetic material-based cover is attached to the
magnetic rubber-based encoder by swaging the one end of the cover
which extending beyond the cylindrical portion of the magnetic
rubber-based encoder.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The present invention relates to an encoder apparatus, or
more specifically an encoder that is included in the encoder
apparatus as one of its components, wherein the encoder apparatus
may be mounted on a rotational member in the automotive vehicle
(such as between the outer and inner races of the wheel bearing
unit on the driving shaft or driven shaft) for detecting the number
of revolutions of the rotational member.
[0003] 2. Description of the Prior Art
[0004] One example of the conventional encoder apparatus that may
be mounted on a rotational member in the automotive vehicle by
pressing the encoder apparatus into the rotational member for
detecting the number of revolutions of the rotational member is
disclosed in Japanese patent application as now published under No.
62(1987)-25267, for example, wherein the encoder apparatus includes
an encoder in the form of a magnetic signal generator ring.
[0005] As described in the above document, the magnetic signal
generator ring is based on a synthetic resin material that is
mechanically strong enough to avoid any possible damages that might
occur on the ring as it is pressed into the rotational member, and
includes an annular synthetic resin magnet that is buried around
the outer peripheral surface of the ring. The synthetic resin
magnet takes the form of a multipole magnet having S polarities and
N polarities magnetized alternately at equal intervals in the
circumferential direction.
[0006] As the encoder apparatus is mounted on the rotational member
in the manner described above, the encoder in the encoder apparatus
may be placed to face opposite the sensor that is located
adjacently to the encoder outside it.
[0007] As the rotational member on which the encoder apparatus is
mounted is thus rotating at the number of revolutions that is
changing every moment, the encoder may magnetically produce pulses
each of which represent the respective ever-changing number of
revolutions and the sensor may detect the ever-changing number of
revolutions by responding to each of the pulses.
[0008] In the conventional encoder apparatus described above,
however, there is a risk that some extraneous matter such as stones
might enter the area between the encoder in the encoder apparatus
and the sensor located to face opposite the encoder outside it. So
that, said extraneous matter such as stones might be engaged
between the encoder and the sensor, and thus it causing damages on
the encoder.
[0009] The side of the encoder facing opposite the sensor is
magnetized as described above, acting as the magnetized surface
having alternate N polarities and S polarities appear at equal
intervals. If this magnetized surface may be damaged by the
extraneous matter such as stones which entering the area between
the encoder and sensor, the sensor would not be able to detect the
number of revolutions correctly because the encoder would fail to
function properly. Thus, this presents a serious disadvantage.
[0010] Another example of the conventional encoder apparatus that
includes an encoder known as the annular encoder is disclosed in
Japanese patent application as now published under No. 2001-241435,
wherein the encoder apparatus may be mounted on a rotational
member, such as between the inner and outer races of the bearing
unit rotating relative to each other, so that it can detect the
number of revolutions. In this conventional encoder apparatus, the
encoder is covered by a nonmagnetic cover on the side thereof
facing opposite the sensor in order to avoid that the damages might
occur on the encoder as described above. Other examples of the
encoder apparatus are disclosed in Japanese patent applications as
now published under No. H5 (1993)-249126, No. H11 (1999)-303879,
and No. 2002-286739, respectively.
[0011] For those recent years, the encoder apparatus that may be
mounted on a rotational member on the automotive vehicle by
pressing the encoder apparatus into the rotational member for
detecting the ever-changing number of revolutions for the
rotational member has more often been used with the FF (front
engine, front drive) vehicle in particular, in which the encoder
apparatus is mounted on the drive shaft and the like, and is used
under the more severe running or ambient conditions.
SUMMARY OF THE INVENTION
[0012] In order to avoid that any damages occur on the encoder in
the encoder apparatus when it is mounted on the rotational member
by pressing it into the rotational member, there are demands for
the encoder apparatus that includes an encoder that is mechanically
strong enough to permit the encoder to withstand any severe or
vigorous ambient or running conditions, thereby protecting the
encoder from such damages more securely.
[0013] In order to solve the problems associated with the prior art
encoder apparatus as described above, the present invention
proposes to provide a cylindrical cover-attached encoder apparatus
that includes a magnetic metal-based body having the cylindrical
shape, a magnetic rubber-based encoder having the cylindrical shape
and formed around the cylindrical portion of the magnetic
metal-based cylindrical body, and a nonmagnetic material-based
cover having the cylindrical shape and mounted on the magnetic
rubber-based encoder for covering the outer peripheral surface of
the cylindrical portion of the encoder.
[0014] It may be understood that as the cylindrical cover-attached
encoder apparatus according to the present invention includes the
magnetic rubber-based cylindrical encoder that may be formed around
the cylindrical portion of the magnetic metal-based cylindrical
body, it can have the improved mechanical strength that enables the
encoder apparatus to be mounted on the rotational member without
causing any damages on the encoder in the encoder apparatus when
the encoder apparatus is pressed into the rotational member.
[0015] It may also be understood that as the magnetic rubber-based
cylindrical encoder has its outer peripheral side covered by the
nonmagnetic material-based cover, it can be protected from any
unfavorable ambient conditions outside it, and it can withstand any
severe or vigorous running or ambient conditions for an extended
period of the time without causing any damages, even when it is
used under such conditions.
[0016] The cylindrical encoder that constitutes one component of
the cylindrical cover-attached encoder apparatus according to the
present invention may be any type of the encoder that is known to
any person skilled in the relevant art. For example, the
cylindrical encoder may be formed by preparing ferrite magnetic
powders (such as strontium ferrite powder, barium ferrite powder
and the like) or rare earth magnetic powders (such as a combination
of neodymium, iron and boron, a combination of samarium, iron and
nitrogen and the like), adding any of the above powders to elastic
element such as synthetic rubber or synthetic resin, mixing them
together, and molding the mixture into the cylindrical shape by
using the vulcanizing, molding process. Then, said molded
cylindrical shape may be magnetized so that S polarities and N
polarities can appear alternately at equal intervals in the
circumferential direction thereof. Finally, the multipole encoder
having the cylindrical shape can be obtained. This cylindrical
encoder may then be attached to the magnetic metal-based
cylindrical body by using any adhesive medium.
[0017] It should be noted that the ferrite magnetic powder or rare
earth magnetic powder and the elastic element such as synthetic
rubber or synthetic resin may preferably have the composition ratio
range of between 70% and 95% by weight.
[0018] The synthetic rubber that may be based on the encoder may
include NBR, H-NBR, ACM, AEM, FKM, EPDM and the like.
[0019] As an alternative form of the cylindrical encoder, it may be
obtained in the following steps. The preliminary foundation
processing may be conducted on the magnetic metal-based cylindrical
body, an adhesive medium may be applied onto the thus foundation
processed cylindrical body, and the rubber material containing the
magnetic materials mentioned above may be bonded to the cylindrical
body by the vulcanizing, molding and bonding process. Finally, the
cylindrical encoder thus obtained may be magnetized as described
above.
[0020] Desirably, the metal-based body having the cylindrical shape
around on which the magnetic rubber-based encoder having the
cylindrical shape is formed may be made from magnetic material
because the magnetic force that may be provided by the magnetic
rubber-based encoder formed around the outer peripheral surface of
the cylindrical body can be supplemented.
[0021] In the cylindrical cover-attached encoder apparatus
described above in accordance with the present invention, the
magnetic metal-based cylindrical body should preferably be formed
by using any of the sintered metals. The sintered metal can be
worked into any desired shape, and this can be done with the high
dimensional precision. Specifically, the inner and outer peripheral
surfaces of the sintered metal-based cylindrical body can be formed
with the drastically enhanced dimensional precision. In short, the
sintered metal can meet both the high precision magnetizing
requirements and the mechanical strength requirements, and the
cylindrical body can be secured in position with the high
stability.
[0022] In the cylindrical cover-attached encoder apparatus
described above in accordance with the present invention, the
magnetic metal-based cylindrical body may also be formed by using
any of the steels.
[0023] In cases where the magnetic metal-based cylindrical body
must be formed with reduced thickness, it is preferable to form the
magnetic metal-based cylindrical body by using a steal material. In
those cases, the cylindrical cover-attached encoder apparatus that
includes the cylindrical body based on the steel material can
ensure the required mechanical strength. For example, the magnetic
metal-based cylindrical body may be formed by using low carbon
steel such as SPCC, SPCE and the like or ferrite stainless steel
such as SUS430, SUS430JIL and the like.
[0024] In any of the before described cylindrical cover-attached
encoder apparatus of the present invention, one end of the
cylindrical portion of the nonmagnetic material-based cover
covering the outer peripheral side of the encoder in the encoder
apparatus may be extended beyond the cylindrical portion of the
encoder in the axial direction of the magnetic metal-based
cylindrical body, and the cover may then be attached to the encoder
by swaging the one end of the cylindrical portion of the cover
extending beyond the cylindrical portion of the encoder
axially.
[0025] This swaging operation ensures that the nonmagnetic
material-based cover can be attached to the encoder in the
simplified way so that the cover can cover the encoder from the
outside. This also ensures that the cover and encoder can be
positioned relative to each other correctly and securely without
being misaligned.
[0026] In any of the before described cylindrical cover-attached
encoder apparatus of the present invention, it is desirable that
the nonmagnetic material-based cylindrical cover has the thickness
of between 0.1 mm and 0.6 mm. In this way, the transmission of the
magnetic force from the encoder through the cover can be improved,
and the cover can be attached to the encoder correctly and easily
by the swaging operation.
[0027] In order to permit the nonmagnetic material-based cover to
meet the requirements for the performance and mechanical strength,
it may be formed by using SUS304, Al, CuZn, Cu and the like.
[0028] In the cylindrical cover-attached encoder apparatus of the
present invention, the magnetic rubber-based cylindrical encoder
may be formed around the outer peripheral surface of the
cylindrical portion of the magnetic metal-based cylindrical body,
and thus the mechanical strength of the encoder apparatus can be
increased so remarkably that any damages that would otherwise occur
when the encoder apparatus is pressed into a particular rotational
member on the automotive vehicle can be avoided.
[0029] The outer peripheral side of the magnetic rubber-based
cylindrical encoder may be covered by the nonmagnetic
material-based cover, and thus the encoder can be protected more
securely from the outside.
[0030] So that, the cylindrical cover-attached encoder can
withstand the more severe or vigorous running or ambient conditions
for an extended period of the time without causing any damages,
even when it is used under such conditions.
[0031] In accordance with any forms of the cylindrical
cover-attached encoder apparatus of the present invention, the
magnetic rubber-based encoder can be protected completely from the
risk of any of the stones, sands, mud, dirty water and the like
coming from the outside and hitting the encoder in the encoder
apparatus, and any wear or breakage that would be caused by those
stones, etc. can be avoided. Thus, the encoder in the encoder
apparatus can be operating properly even under unfavorable
environmental conditions almost permanently, and can provide pulses
that represent the number of revolutions accurately. Thus, those
pulses from the encoder can be transmitted through the nonmagnetic
material-based cover, and can be detected accurately by the
sensor.
[0032] It may be understood from the foregoing description that one
end of the cylindrical portion of the nonmagnetic material-based
cover covering the outer peripheral side of the encoder is
extending beyond the cylindrical portion of the encoder in the
axial direction of the magnetic metal-based cylindrical body. And,
the cover may be attached to the encoder simply by swaging the one
end of the cylindrical portion of the cover extending axially
beyond the cylindrical portion of the encoder, thereby the
nonmagnetic material-based cover can cover the encoder from outside
it. This swaging operation can be carried out to ensure that the
cover can be positioned correctly relative to the encoder without
being misaligned.
[0033] It may be appreciated from the foregoing description that
the cylindrical cover-attached encoder apparatus of the present
invention may be used with the FF vehicle, for example, although it
may also be used with other types of vehicles such as FR (front
engine, rear drive) vehicle and RR (rear engine, rear drive)
vehicle. In any case, the encoder apparatus can be mounted on the
drive shaft, in which the magnetic rubber-based encoder can have
its magnetized surface protected by the nonmagnetic material-based
cover, and can withstand any severe or vigorous running or
environmental conditions for an extended period of the time, even
when it is used under such conditions. Despite such unfavorable
situation, the encoder in the encoder apparatus of the present
invention can produce pulses that represent the number of
revolutions correctly, and the sensor can detect the number of
revolutions accordingly by responding to the pulses.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 (a) is a longitudinal sectional view of a preferred
embodiment of the cylindrical cover-attached encoder apparatus
according to the present invention, although some non-critical
parts or elements are not shown, and FIG. 1 (b) is a plan view of
the cylindrical cover-attached encoder apparatus shown in FIG. 1
(a);
[0035] FIG. 2 is a longitudinal sectional view of another preferred
embodiment of the cylindrical cover-attached encoder apparatus
according to the present invention, showing how the encoder
apparatus of FIG. 1 may be mounted on a rotational member in the
automotive vehicle, although some non-critical parts or elements
are not shown; and
[0036] FIG. 3 is a longitudinal sectional view of still another
preferred embodiment of the cylindrical cover-attached encoder
apparatus, showing how the encoder apparatus may be mounted on a
rotational member in the automotive vehicle, although some
non-critical parts or elements are not shown.
DETAILS OF THE PREFERRED EMBODIMENTS
[0037] The following describes several particular preferred
embodiments of the cylindrical cover-attached encoder apparatus
according to the present invention by referring to the accompanying
drawings.
[0038] (Embodiment 1)
[0039] The cylindrical cover-attached encoder apparatus according
to the first embodiment of the present invention includes the
components that will be described specifically below.
[0040] As one component of the encoder apparatus, a magnetic
metal-based cylindrical body 1 may be formed by using a sintered
metal of magnetic materials.
[0041] As another component of the encoder apparatus, an encoder
may be formed in the following steps. A ferrite magnetic powder
(such as strontium ferrite powder, barium ferrite powder and the
like) and a rubber chemical are prepared, and may be added to NBR
(acrylonitrile butadiene rubber). Note that the strontium ferrite
powder has the composition ratio of 88% by weight relative to the
other elements. Then, they may be mixed together, and a rubber in
its unvulcanized state may thus be obtained. Finally, this rubber
is placed in a mold where it may be vulcanized, shaped into an
encoder 2, and bonded to the outer peripheral surface of the
cylindrical body 1, as shown in FIG. 1 (a).
[0042] In this embodiment, as shown in FIG. 1 (a), the encoder 2
may be formed to have a cylindrical portion 2b and annular portions
2a, 2a, in which the cylindrical portion 2b may be bonded to the
outer peripheral surface of the cylindrical portion of the
cylindrical body 1 and the annular portions 2a, 2a may be bonded to
the upper lateral surface and lower lateral surface of the
cylindrical body 1, respectively, during the vulcanizing, molding
and bonding process.
[0043] Then, the cylindrical portion 2b of the encoder 2 thus
obtained may be magnetized to have S polarities and N polarities
appear alternately at equal intervals in the circumferential
direction. Thus, the multipole encoder 2 may be obtained. In this
way, this multipole encoder 2 includes the magnetic rubber that is
formed around the outer peripheral surface of the cylindrical
portion of the magnetic metal-based cylindrical body 1.
[0044] As still another component of the encoder apparatus, a
cylindrical cover 3 may be provided by using SUS304 steel plate of
0.3 mm thickness, for example. As it may be seen from FIG. 1 (a),
the cylindrical cover 3 has an annular portion 3a.
[0045] This cylindrical cover 3 may be mounted to the outer
peripheral side of the cylindrical encoder 2 formed around the
outer peripheral surface of the cylindrical portion of the
cylindrical body 1, this mounting being made in the direction of an
arrow 5 in FIG. 1 (a).
[0046] As it may be seen from FIG. 1 (a), the cylindrical cover 3
has an end 3c extending beyond the cylindrical portion 2b of the
encoder 2 in the axial direction of the magnetic metal-based
cylindrical body 1.
[0047] The cylindrical cover-attached encoder apparatus may be
completed by swaging the end 3c of the cylindrical cover 3 toward
the direction of an arrow 4, thereby attaching the cover 3 to the
encoder 2.
[0048] In this embodiment, as shown in FIG. 1 (a), the cylindrical
encoder 2 based on the magnetic rubber may be formed around the
outer peripheral surface of the cylindrical body 1, and the
cylindrical cover 3 may then be mounted around the outer peripheral
side of the cylindrical portion 2b of the cylindrical encoder 2, so
that the inner peripheral wall of the cover 3 can engage the outer
peripheral side of the cylindrical encoder 2, and finally the cover
3 may be attached to the encoder 2 by swaging the end 3c of the
cover 3. The cylindrical body 1, the cylindrical encoder 2 and the
cylindrical cover 3 are thus combined together into a single unit,
thus completing the cylindrical cover-attached encoder apparatus of
the present invention. Specifically, the cylindrical cover-attached
encoder apparatus includes the cylindrical encoder 2, the magnetic
metal-based cylindrical body 1, and the nonmagnetic material-based
cylindrical cover 3 in such a way that the cylindrical encoder 2 is
held like a sandwich between the magnetic metal-based cylindrical
body 1 and the nonmagnetic material-based cylindrical cover 3.
[0049] Therefore, in the cylindrical cover-attached encoder
apparatus of the present invention of this embodiment 1, the
cylindrical encoder 2 made of magnetic rubber is strengthen by the
cylindrical body 1 made of magnetic metal, and the outer peripheral
side of the cylindrical encoder 2 made of magnetic rubber is
covered by the cylindrical cover 3 made of nonmagnetic
material.
[0050] So that, in terms of the mechanical strength, the encoder 2
can be reinforced by the cylindrical body 1. Furthermore, the
encoder 2 can be protected by the nonmagnetic metal-based
cylindrical cover 3 from the outside. This permits the encoder
apparatus to be positioned correctly when it is mounted on any
rotational member on the automotive vehicle. Also, when it is used
in conjunction with the sensor, the encoder 2 can provide the
number of revolutions correctly, which can be detected by the
sensor accordingly.
[0051] Now, the following describes how the encoder apparatus
according to this embodiment can be used. In the following
description, it is supposed that the encoder apparatus is used with
FF (front engine, front drive) automotive vehicle. Then, the
encoder apparatus may be mounted on a particular rotational member,
such as a drive shaft 7, by pressing the encoder apparatus into the
drive shaft 7 in the direction of an arrow 9 in FIG. 2. With the
encoder apparatus being mounted on the drive shaft 7 as shown in
FIG. 2, the sensor 10 may be placed adjacently to the outer
peripheral side of the cylindrical portion 3b of the cover 3. This
ensures that the encoder 2 and sensor 10 can be operational for an
extended period of the time so that the sensor 10 can detect the
number of revolutions by responding to the pulses emitted from the
encoder 2 mounted on the outer periphery of the drive shaft 7
rotating about the rotary axis 8.
[0052] (Embodiment 2)
[0053] In this embodiment, it is assumed that the cylindrical
cover-attached encoder apparatus may be mounted on a rotational
member, such as a bearing unit including the inner and outer races
rotating relative to each other through the rolls interposed
between the inner and outer races. As shown in FIG. 3, a
cylindrical core metal is provided so that it can be mounted on the
outer periphery of the outer race of the bearing unit, and an
encoder is provided so that it can be formed on the outer periphery
of the core metal. A nonmagnetic material-based cylindrical cover
is provided so that it can be attached to the outer peripheral side
of the encoder by using the swaging process.
[0054] It may be seen from FIG. 3 that the encoder apparatus is
mounted on the wheel bearing unit on the driven shaft, including
the inner race 16a and outer race 16b rotating relative to each
other though the intervening rolls 17.
[0055] As a component of the encoder apparatus, a cylindrical core
metal 11 may be provided by using a low carbon steel such as SPCC.
The cylindrical core metal 11 may be formed to include a
cylindrical portion 11b and a flange portion 11a. The cylindrical
portion 11b is placed on the outer periphery of the rotating outer
race 16b of the wheel bearing unit. The flange portion 11a is
extending inwardly (the left side in FIG. 3) in the radial
direction from the axial outer end (the upper side in FIG. 3) of
the cylindrical portion 11b.
[0056] Then, the preliminary foundation processing may be conducted
on the outer peripheral surface of the cylindrical core metal 11,
onto which an adhesive medium may be applied.
[0057] As another component of the encoder apparatus, a cylindrical
encoder may be formed in the following steps. A ferrite magnetic
powder (such as a mixture of strontium ferrite powder and barium
ferrite powder) and a rubber chemical are prepared, and may be
added to H-NBR (hydrogen-added acrylonitrile butadiene rubber).
Note that the ferrite magnetic powder has the composition ratio of
88% by weight relative to the other elements. Then, they may be
mixed together, and a rubber in its unvulcanized state may thus be
obtained. Finally, this rubber is placed in a mold where it may be
vulcanized, shaped into the magnetic rubber-based cylindrical
encoder 13, and bonded on the outer peripheral surface of the
cylindrical core 11.
[0058] In this embodiment, as shown in FIG. 3, the magnetic
rubber-based cylindrical encoder 13 includes a cylindrical portion
13b and an annular portion 13a, and the vulcanizing, molding and
bonding process may be carried out on the cylindrical encoder 13
with its cylindrical portion 13b being bonded to the outer
peripheral side of the cylindrical portion 11b of the core metal 11
and the annular portion 13a being bonded to the flange portion 11a
of the metal core 11.
[0059] Then, the magnetic rubber-based cylindrical encoder 13 may
be magnetized so that S polarities and N polarities can appear
alternately at equal intervals in the circumferential direction of
the cylindrical portion 13b, and may be provided on the outer
peripheral surface of the cylindrical portion 11b of the SPCC
steel-based cylindrical core metal 11.
[0060] As still another component of the encoder apparatus, a
cylindrical cover 14 may be provided by using a SUS304 steel plate
of 0.3 mm thickness, including a cylindrical portion 14b and a
flange portion 14a extending inwardly (the left side in FIG. 3) in
the radial direction from the axial outer end (the upper end in
FIG. 3) of the cylindrical portion 14b.
[0061] Then, the SUS304 steel-based cylindrical cover 14 may be
mounted on the outer peripheral side of the cylindrical encoder 13
formed on the outer periphery of the cylindrical portion 11b of the
cylindrical core metal 11, in the same manner as described for the
preceding embodiment 1.
[0062] The cylindrical cover 14 has an end 14c extending beyond the
cylindrical portion 13b of the encoder 13 in the axial direction of
the cylindrical portion 11b of the core metal 11, and may be
attached to the encoder 13 by swaging the end 14c in the direction
of an arrow 15. The cylindrical cover-attached encoder apparatus is
thus completed.
[0063] Similarly to the preceding embodiment 1, the cylindrical
magnetic rubber-based encoder 13 is firmly held like a sandwich as
shown in FIG. 3. Therefore, in the cylindrical cover-attached
encoder apparatus of the present invention, the cylindrical encoder
13 made of magnetic rubber is strengthen by the core metal 11 made
of magnetic metal, and the outer peripheral side of the cylindrical
encoder 13 made of magnetic rubber is covered by the cylindrical
cover 14 made of nonmagnetic material. So that, in terms of the
mechanical strength, the encoder 13 can be reinforced by the core
metal 11. Furthermore, the encoder 13 can be protected by the
nonmagnetic metal-based cylindrical cover 14 from the outside. This
permits the encoder apparatus to be positioned correctly when it is
mounted on any rotational member on the automotive vehicle. Also,
when it is used in conjunction with the sensor, the encoder 13 can
provide the number of revolutions correctly, which can be detected
by the sensor accordingly.
[0064] The cylindrical cover-attached encoder apparatus thus
obtained in accordance with this embodiment may be mounted on a
particular rotational member in the automotive vehicle, such as the
outer race 16b of the wheel bearing unit on the driven shaft. With
the encoder apparatus being mounted on the outer race 16b as shown
in FIG. 3, the sensor 10 may be placed adjacently to the outer
peripheral side of the cylindrical portion of the cover 14. This
ensures that the encoder 13 and sensor 10 can be operational for an
extended period of the time so that the sensor 10 can detect the
number of revolutions by responding to the pulses emitted from the
encoder 13 mounted on the outer periphery of the outer race 16b of
the rotating bearing unit.
[0065] Although the present invention has been described so far
with reference to several particular preferred embodiments thereof,
it should be understood that various changes and modifications may
be made to those embodiments without departing from the spirit and
scope of the invention as defined in the appended claims.
* * * * *