SPECIFICATION
TITLE OF THE INVENTION
ROLLING BEARING UNIT WITH ENCODER FOR SUPPORTING WHEEL
TECHNICAL FIELD
[0001] The present invention relates to a rolling bearing unit with an
encoder for supporting a wheel of an automobile so as to be able to rotate
freely with respect to the suspension, and for determining the rotational
speed of that wheel. More specifically, the present invention relates to an
improvement of a rolling bearing unit with encoder that comprises
construction wherein a cover, which covers an opening on the inside end in
the axial direction of an internal space where the encoder is located, is fitted
inside and fastened to the inside end section in the axial direction of the
outer ring.
BACKGROUND ART
[0002] Various construction for a rolling bearing unit with a rotational
speed detector for supporting a wheel by the suspension of an automobile so
as to be able to rotate freely, and for determining the rotational speed of that
wheel has been known previously. In the case of any of the conventional
construction, a detecting section of a sensor that is supported by and
fastened to a non-rotating portion is made to face a detected surface of an
encoder that is supported by and fastened to part of a hub that rotates
together with the wheel. In this construction, the rotational speed of the
wheel that rotates with the encoder is found based on the frequency or period
of an output signal from the sensor that changes as the encoder rotates.
[0003] In order to protect the encoder of this kind of rolling bearing unit
with a rotational speed detector from damage due to muddy water or dust
adhering to the encoder, or, in order to prevent foreign matter such as
magnetic powder from adhering to the encoder and damaging the reliability
of the rotational speed detector that uses the encoder, construction such as
disclosed in JP 4206550 (B2) and DE 19644744 (A1) of separating the

encoder from the outside by a cover made of a non-magnetic plate is
conventionally known. FIG. 11 illustrates an example of conventional
construction as disclosed in JP 4206550 (B2). This conventional
construction comprises a rolling bearing unit 2 with an encoder in which an
encoder 1 is assembled, and a sensor 4 that is supported by and fastened to a
knuckle 3 of the suspension.
[0004] In the rolling bearing unit 2 with encoder, the encoder 1 is
supported by and fastened to the inside end section in the axial direction of
the hub 6 of the rolling bearing unit 5 so as to be concentric with the hub 6.
In addition to the hub 6, the rolling bearing unit 5 comprises an outer ring 7
and a plurality of rolling elements 8. The outer ring 7 has double rows of
outer ring raceways 9 around the inner circumferential surface and a
stationary flange 10 on the outer circumferential surface. During operation,
the outer ring 7 is supported by the knuckle 3 and does not rotate.
[0005] The hub 6 comprises a main hub body 11, and an inner ring 12 that
is connected and fastened to the main hub body 11 by a crimped section 13
that is formed on the inside end section in the axial direction of the main hub
body 11; the hub 6 having double rows of inner ring raceways 14 around the
outer circumferential surface thereof, and being supported on the
inner-diameter side of the outer ring 7 so as to be concentric with the outer
ring. Moreover, a rotating side flange 15 for supporting the wheel is
provided on the outside end section in the axial direction of the main hub
body 11 in the portion that protrudes further outward in the axial direction
than the opening on the outside end in the axial direction of the outer ring 7.
The rolling elements 8 are located between both outer ring raceways 9 and
both inner ring raceways 14, with the rolling elements supported by a cage
16 in each row, so as to be able to roll freely. Furthermore, both end sections
in the axial direction of the internal space 17 where the rolling elements 8
are located are covered by a seal ring 18 and a cover 19. In this
specification, the "outside" in the axial direction is the side toward the
outside in the width direction of the vehicle when assembled in the
suspension. On the other hand, the "inside" in the axial direction is the side
toward the center in the width direction of the vehicle when assembled in the

suspension.
[0006] The cover 19 is formed using a non-magnetic metal plate such as an
aluminum alloy plate, or austenitic stainless steel plate, or some other
non-magnetic material. This kind of cover 19 comprises a cylindrical
section 20 that extends in the axial direction, and a flat plate section 21 that
is bent and extends inward in the radial direction from the inside end section
in the axial direction of this cylindrical section 20. In the construction in
FIG. 11, the rolling bearing unit 5 is applied to a non-driven wheel (rear
wheel for a FF vehicle, front wheel for a FR vehicle or MR vehicle), so the flat
plate section 21 is a circular plate shape that covers the entire opening on
the inside end in the axial direction of the outer ring 7. On the other hand,
in the case of a rolling bearing unit for a driven wheel (front wheel for a FF
vehicle, rear wheel for a FR or MR vehicle, and any wheel for a 4WD vehicle),
in the construction disclosed in DE 19644744 (Al), the flat plate section is
ring shaped in order that the drive shaft can be inserted to the
inner-diameter side of the cover. In either case, the cover 19 is such that
the cylindrical section 20 fits inside the inside end section in the axial
direction of the outer ring 7 with an interference fit, and is fastened to this
inside end section in the axial direction of the outer ring 7.
[0007] The base end section of the encoder 1 is fitted onto a shoulder
section 22 that is formed on the inside half in the axial direction of the inner
ring 12, which corresponds to a portion toward the inside end of the hub 6, so
that the encoder 1 is concentrically supported by and fastened to the hub 6.
The encoder 1 comprises a support ring 23 that is formed into a circular ring
shape with an L-shaped cross section by bending a magnetic metal plate
such as low carbon steel plate, and a main encoder body 24 that is made
using a permanent magnet such as a rubber magnet. This main encoder
body 24 is magnetized in the axial direction, and by alternating the
magnetization direction at uniform intervals in the circumferential direction,
S poles and N poles are alternated at uniform intervals on the inside surface
in the axial direction, which is the detected surface. The detected surface of
this kind of main encoder body 24 is made to closely face through a small gap
the outside surface in the axial direction of the flat plate section 21 of the

cover 19 (surface on the internal space side). In other words, the cover 19 is
pushed onto the inside end section in the axial direction of the outer ring 7
until the outside surface in the axial direction of the flat plate section 21
closely faces the detected surface of the main encoder body 24.
[0008] Furthermore, with the sensor 4 supported by and fastened to the
knuckle 3, the detecting section of the sensor 4 is brought into contact with
the inside surface (surface on the outer space side) in the axial direction of
the flat plate section 21. In the state, the detecting section faces the
detected surface of the main encoder body 24 by way of the flat plate section
21. In this state, as the main encoder body 24 rotates together with the hub
6, the S poles and N poles on the detected surface come by near the detecting
section of the sensor 4 alternately, which causes the output of the sensor 4 to
change. The frequency of this change is proportional to the rotational speed
of the hub 6, and the period of this change is inversely proportional to the
rotational speed, so based on either or both the frequency and period, the
rotational speed of the wheel that is fastened to the hub 6 is found.
[0009] In the case of the conventional construction illustrated in FIG. 11,
the permanent magnet main encoder body 24 and the external space are
separated by the non-magnetic cover 19, so it is possible to prevent foreign
matter such as magnetic powder from adhering to the detected surface of the
main encoder body 24. As a result, this detected surface is maintained in a
clean state, making it possible to maintain reliability of the rotational speed
detector that uses this main encoder body 24. However, there is a need to
improve the precision related to the distance between the detected surface of
the main encoder body 24 and the detecting section of the sensor 4.
[0010] In other word, when the cylindrical section 20 is fitted inside the
inside end section in the axial direction of the outer ring 7 with an
interference fit in order for the cover 19 to be supported by and fastened to
the outer ring 7, a force is applied in a direction inward in the radial
direction to the flat plate section 21 that is on the inner-diameter side of the
cylindrical section 20. Particularly, in the case of this conventional
construction, the radius of curvature of a bent section that exists at the
continuous section between the outer circumferential edge of the flat plate

section 21 and the edge on the inside end in the axial direction of the
cylindrical section 20 is small (in other words, bent with large curvature),
and the portion that fits inside and is fastened to the outer ring 7 with an
interference fit extends to nearly the outer circumferential edge of the flat
plate section 21. Therefore, the force inward in the radial direction that is
applied to the flat plate section 21 becomes considerably large, and due to
this force the flat plate section 21 deforms in the direction of thickness
(inward and outward in the axial direction) so as to curve.
[0011] The deformation direction and the amount of deformation cannot be
regulated or predicted, so the position in the axial direction of the portion on
the flat plate section 21 between the detected surface of the main encoder
body 24 and the detecting section of the sensor 4 cannot be regulated with
good precision. For example, when the sensor 4 is positioned by the
detecting section of the sensor 4 coming in contact with the inside surface in
the axial direction of the flat plate section 21 (surface on the external space
side), that positioning become inaccurate when the flat plate section 21 is
distorted. As a result, there is fluctuation in the density of the magnetic
flux that reaches the detecting section of the sensor 4 from the detected
surface of the main encoder body 24, which is disadvantageous from the
aspect of maintaining the reliability of the rotational speed detection.
[Related Literature]
[Patent Literature]
[0012]
[Patent Literature l] JP4206550(B2)
[Patent Literature 2] DE19644744(Al)
SUMMARY OF THE INVENTION
[Problem to be Solved by the Invention]
[0013] In consideration of the situation above, it is the object of the present
invention to achieve construction that is capable of preventing deformation
in the axial direction of the portion of the cover, which covers the opening on

the inside end in the axial direction of the internal space where the encoder
is located, further on the inner-diameter side than the portion that is fitted
into and fastened to the inside end section in the axial direction of the outer
ring, or in other words, the flat plate section of the cover that is bent and
extends inward in the radial direction from the inside end section in the
axial direction of the cylindrical section of the cover, when the cover is fitted
into and fastened to the outer ring.
[Means for Solving the Problems]
[0014] The rolling bearing unit with an encoder for supporting a wheel of
the present invention, similar to a conventional rolling bearing unit with an
encoder for supporting a wheel has: an outer ring, a hub, a plurality of
rolling elements, and an encoder and a cover.
[0015] The outer ring has double-row outer ring raceways around the inner
circumferential surface thereof, and is supported by and fastened to a
suspension during use so as not to rotate. The hub has double-row inner
ring raceways around the outer circumferential surface thereof, and with a
wheel supported by and fastened thereto during use, rotates together with
the wheel. The rolling elements are provided such that there are a plurality
of rolling elements located in each row between both outer ring raceways and
both inner ring raceways. The encoder is supported by and fastened to the
hub so as to be concentric with the hub, with the inside surface in the axial
direction thereof being a detected surface having a magnetic characteristic
that alternately changes in the circumferential direction.
[0016] Furthermore, the cover is made of a non-magnetic plate material,
and comprises a cylinder section that extends in the axial direction, and a
flat plate section that is bent and extends inward in the radial direction from
the inside end section in the axial direction of the cylinder section. Together
with this cylinder section fitting into the inside end section in the axial
direction of the outer ring, the flat plate section closely faces the detected
surface of the encoder.
[0017] Particularly, in the rolling bearing unit with an encoder for
supporting a wheel of the present invention, a non-contact section is formed
all the way around the inside end section in the axial direction of the cylinder

section of the cover so as not to come in contact with the inner
circumferential surface of the outer ring when the cover is fitted inside and
fastened to the outer ring.
[0018] In other words, the non-contact section has an outer diameter that
is smaller than the inner diameter of the inside end section in the axial
direction of the outer ring. Moreover, the dimension in the axial direction of
the non-contact section is two times or more, or preferably three times or
more the thickness dimension of the plate member of the cover. When
finding this value that is two times (three times) the value of the thickness,
the value of the dimension in the axial direction of the non-contact section is
the value of the distance between the position in the axial direction of the
inside surface in the axial direction of the flat plate section of the cover and
the position in the axial direction of the starting point of contact between the
cylinder section of the cover and the outer ring in the state where the
cylinder section of the cover is fitted inside and fastened to the inside end
section in the axial direction of the outer ring with an interference fit and
that cylinder section of the cover is elastically deformed.
[0019] By providing this kind of non-contact section, when the cover is
fitted into the inside end section in the axial direction of the outer ring, the
cylinder section is fitted into the inside end section in the axial direction of
the outer ring so that only the portion further on the outside in the axial
direction than the non-contact section fits inside with an interference fit.
[0020] When embodying the rolling bearing unit with an encoder for
supporting a wheel of the present invention, the non-contact section is
preferably formed into a partial conical cylindrical shape that is inclined in a
direction such that the diameter becomes smaller going inward in the axial
direction. Alternatively, the non-contact section is preferably composed of a
small-diameter stepped section with a stepped section being located between
the small-diameter stepped section and the portion near the outside in the
axial direction.
[0021] When embodying the rolling bearing unit with an encoder for
supporting a wheel of the present invention, preferably the inside end
surface in the axial direction of the outer ring protrudes inward in the axial

direction more than the inside end surface of the flat plate section.
Furthermore, when embodying the rolling bearing unit with an encoder for
supporting a wheel of the present invention, preferably a gap is formed
between the detected surface of the encoder and the outside surface in the
axial direction of the flat plate section of the cover that faces the detected
surface of the encoder, and this gap is larger than a gap which is formed
between the outside end surface in the axial direction of the cylinder section
of the cover and an inside surface in the axial direction of a counterbore
which is formed further near the inside end in the axial direction of the outer
ring than the outer ring raceway and faces the outside end surface in the
axial direction of the cylinder section of the cover. Alternatively, or
additionally, it is preferred that the gap between the detected surface of the
encoder and the outside surface in the axial direction of the flat plate section
of the cover that faces the detected surface of the encoder be larger than a
gap between the inside end surface in the axial direction of the hub and the
outside surface in the axial direction of the cover that faces the inside end
surface in the axial direction of the hub.
[Effect of the Invention]
[0022] As described above, with the rolling bearing unit with an encoder
for supporting a wheel of the present invention, when a cover, which covers
the opening on the inside end in the axial direction of the internal space
where the encoder is located, is fitted and fastened in the inside of the inside
end section in the axial direction of the outer ring, a force that is applied
inward in the radial direction to the flat plate section of the cover is reduced
by causing the nonxontact section that exists between the fitted and
fastened cylinder section and the flat plate section, so it is possible to
suppress the transmission of that force to the flat plate section, and thus it is
possible to prevent strain deformation in the axial direction of this flat plate
section. Consequently, it is possible to regulate with good precision the
position in the axial direction of the flat plate section that faces the detected
surface of the encoder and the surface accuracy thereof including the
perpendicularity and the like. As a result, when combined with a sensor for

rotational speed detection, the density of the magnetic flux that leaves from
the detected surface of the encoder and reaches the detecting section of the
sensor can be sufficiently and surely maintained, and thus it is possible to
maintain the reliability for detecting the rotational speed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a partial cross-sectional view of a first example of an
embodiment of the present invention.
FIG. 2 is a partial enlarged cross-sectional view of the top part in
FIG. 1, and illustrates the shape of a cover in the first example of an
embodiment of the present invention.
FIG. 3 is a partial enlarged cross-sectional view of the top part in
FIG. 1, and illustrates the shape of a cover in a second example of an
embodiment of the present invention.
FIG. 4A and FIG. 4B are similar to FIG. 2 and FIG. 3, where FIG. 4
is a variation of the first example and FIG. 4B is a variation of the second
example, wherein the outer circumferential surface of the non-contact
section is coated with a seal material.
FIG. 5 is a partial enlarged cross-sectional view illustrating a third
example of an embodiment of the present invention.
FIG. 6 is a partial enlarged cross-sectional view illustrating a fourth
example of an embodiment of the present invention.
FIG. 7 is a partial enlarged cross-sectional view illustrating a fifth
example of an embodiment of the present invention.
FIG. 8 is a partial enlarged cross-sectional view illustrating a sixth
example of an embodiment of the present invention.
FIG. 9 is a partial enlarged cross-sectional view illustrating a
seventh example of an embodiment of the present invention.
FIG. 10 is a partial enlarged cross-sectional view illustrating a
variation of the seventh example, wherein the outer circumferential surface
of the non-contact section is coated with a seal material.
FIG. 11 is a partial cross-sectional view illustrating an example of
conventional construction.

MODES FOR CARRYING OUT THE INVENTION
[0024]
[Example 1]
FIG. 1 and FIG. 2 illustrate a first example of an embodiment of the
present invention. A feature of the rolling bearing unit with an encoder for
supporting a wheel of the present invention, including this example, is
construction wherein as a cover 19a to 19d is fitted into and fastened to the
inside end section in the axial direction of an outer ring 7 in order to cover
the opening on the inside end in the axial direction of an internal space 17
where rolling elements 8 and an encoder 1 are located, deformation in the
thickness direction (axial direction of the bearing unit that includes this
cover) of side plate sections 21 of the cover 19a to 19d is suppressed. The
construction and functions of other parts are the same as in the conventional
rolling bearing unit with an encoder for supporting a wheel, so drawings and
explanations of those parts are simplified or omitted, with the explanation
below centering on the features of the present invention.
[0025] The cover 19a to 19d is made using a non-magnetic plate such as
austenitic stainless steel plate such as SUS304, aluminum alloy plate, or
synthetic resin plate, and comprises a cylindrical section 20 that extends in
the axial direction on the outer circumference section of the cover 19a to 19d,
and a flat plate section 21 on the inside end section in the axial direction that
is bent and extends inward in the radial direction from the cylindrical
section 20. The cylindrical section 20 is fitted into and fastened to the
inside end section in the axial direction of the outer ring 7 with an
interference fit. In this state, the outside surface in the axial direction of
the flat plate section 21 (surface on the internal space side) is made to closely
face through a minute gap 25 a detected surface (inside surface in the axial
direction) of a main encoder body 24 of an encoder 1 that is fitted onto and
fastened to a portion of a hub 6 near the inside end in the axial direction.
[0026] In the first example of an embodiment of the present invention, a
non-contact section 26a is formed all the way around the inside end section
in the axial direction of the cylindrical section 20 of the cover 19a. In this

example, the non-contact section 26a has a partial conical cylindrical shape
that is inclined in a direction such that the diameter becomes smaller going
inward in the axial direction. Here, the non-contact section 26a means a
portion of the cylindrical section 20 that does not come in contact with the
inner circumferential surface of the outer ring 7 when the cylindrical section
20 of the cover 19a is fitted into and fastened to the inside end in the axial
direction of the outer ring 7 with an interference fit and the cylindrical
section 20 of the cover 19a elastically deforms. The end section on the small
diameter side (inside end section in the axial direction) of this non-contact
section 26a has an outer diameter D26 smaller than the inner radius R7 of the
inside end section in the axial direction of the outer ring 7 (R7 > D26).
Therefore, when the cover 19a is fitted into the inside end section in the axial
direction of the outer ring 7, the inner circumferential surface of the outer
ring 7 and the outer circumferential surface of the cylindrical section 20 of
the cover 19a do not come in contact in the axial direction at the non-contact
section 26a, without both circumferential surfaces pushed in the radial
direction by each other. The portion of the cylindrical section 20 that is
fitted into the inside end in the axial direction of the outer ring 7 with an
interference fit is only the portion nearer to the outside in the axial direction
than the non-contact section 26a.
[0027] Moreover, the dimension L26 in the axial direction of the non-contact
section 26a is two times or greater than the thickness t19 of the plate
material of the cover 19a (L26 > 2t19), and preferably three times or greater
(L26 > 3t19). The flat plate section 21 is bend and extends inward in the
radial direction from the end section on the small-diameter side (inside end
section in the axial direction) of the non-contact section 26a. From the
aspect of suppressing deformation of the flat plate section 21, the larger the
dimension L26 in the axial direction is, the more it is preferable. However,
when the dimension L26 in the axial direction is excessively large, the effect
of suppressing deformation cannot increase any further, and the dimension
in the axial direction of the interference fit that contributes to fastening the
cover 19a to the outer ring 7 becomes short, which is disadvantageous from
the aspect of maintaining the support strength of the cover 19a. Therefore,

the dimension L26 in the axial direction is 50% or less than the length in the
axial direction of the cover 19a (L26 < 0.5 L19), and preferably about 20% to
35%. In this example, when the cover 19a is fitted into and fastened to the
inside end section in the axial direction of the outer ring 7, there is a
possibility that part in the axial direction of the portion of the cylindrical
section 20 that is a partial conical cylindrical shape in the free state will
come in contact with the inner circumferential surface of the outer ring 7, so
the dimension L26 in the axial direction of the non-contact section 26a is
determined as the value of the distance between the position in the axial
direction of the inside surface in the axial direction of the flat plate section
21 of the cover 19a and the starting point of contact between the cylindrical
section of the cover 19a and the outer ring 7 (starting point of the fit) when
the cover 19a is fastened to the outer ring 7 and the outer circumference
section of the cover 19a has elastically deformed, instead of the value
measured in the free state.
[0028] From the aspect of preventing deformation due to the interference
fit, in the relationship with the thickness t19 of the cover 19a, it is realistic for
the dimension L26 to be about five times the thickness t19 of the cover 19a (L26
< 5 t19). When generally taking into consideration a good balance between
the maintenance of the support strength of the cover 19a and the prevention
of deformation, the most preferable is that the dimension L26 in the axial
direction be regulated to about three to four times the thickness t19 of the
cover 19a, or in other words L26 = (3 to 4)t19. However, for the reason of
sufficiently being able to maintain the dimension L20 in the axial direction of
the cylindrical section 20, as long as it is possible to maintain the dimension
in the axial direction of the fitting section even though the dimension L26 in
the axial direction is increased, it is possible for the dimension L26 in the
axial direction to even exceed five times the thickness t19 of the cover 19a.
However, increasing the dimension L26 in the axial direction to greater than
ten times the thickness t19 of the cover 19a is unrealistic.
[0029] When fitting the cylindrical section 20 of the cover 19a into the
inside end section in the axial direction of the outer ring 7, only the portion of
the cylindrical section 20 that is nearer to the outside in the axial direction

than the non-contact section 26a is fitted inside the outer ring with an
interference fit. The portion of the cylindrical section 20 that is near the
inside end in the axial direction and that is on the outer-diameter side of the
flat plate section 21 is constructed by the non-contact section 26a, and when
the cover 19a fitted inside and fastened to the inside end section in the axial
direction of the outer ring 7, there is a gap 28 between the outer
circumferential surface of the non-contact section 26a and the inner
circumferential surface of the inside end section in the axial direction of the
outer ring7. Therefore, the outer circumferential surface of this non-contact
section 26a is not pressed inward in the radial direction. In this example,
the position in the axial direction of the inside end surface in the axial
direction of the cover 19a (surface on the external space side) coincides with
the position in the axial direction of the inside end surface of the outer ring 7,
and the cover 19a does not protrude inward in the axial direction further
than the outer ring 7.
[0030] The portion that is fitted into the inside end section in the axial
direction of the outer ring 7, and that is located in the part of the cylindrical
section 20 that is nearer the outside in the axial direction than the
non-contact section 26a is strongly pressed inward in the radial direction.
However, the non-contact section 26a exists all the way around between the
portion in the axial direction that is fitted into the outer ring 7 with an
interference fit and the flat plate section 21. Therefore, even when a strong
force is applied inward in the radial direction to the portion that is fitted into
the outer ring 7 with an interference fit, a large portion of that force is
reduced by causing the non-contact section 26a that is located between the
portion that is fitted into the outer ring 7 with an interference fit and the flat
plate section 21 to deform, and is not reach the flat plate section 21. As a
result, strain deformation in the axial direction of the flat plate section 21
that extends inward in the radial direction from the outer circumference
section of the cover 19a is prevented, and the position in the axial direction of
the flat plate section 21 that faces the detected surface (inside surface in the
axial direction) of the main encoder body 24 of the encoder 1 can be regulated
with good precision. Moreover, the squareness of this portion is also good.

In other words, the shift in the portion on the inside surface in the axial
direction of the flat plate section 21 that comes in contact with the detecting
portion of the sensor 4a from a virtual plane that is orthogonal to the center
axis can be kept to zero or very small.
[0031] As a result of being able to regulate the position in the axial
direction of the portion of the flat plate section 21 that faces the detected
surface of the encoder 1 and the surface precision of this section such as the
perpendicularity, with good precision, it is possible, when the detecting
section of the sensor 4a for detecting rotational speed is in contact with the
inside surface in the axial direction of the flat plate section 21, to keep that
posture of the sensor 4a and the position in the axial direction of the
detecting section within the design values with good precision. Also, with
the detecting section of the sensor 4a and the detected surface of the main
encoder body 24 facing each other by way the flat plate section 21 (in a state
with the encoder and the rotational speed detecting sensor assembled
together), the density of the magnetic flux that reaches the detecting section
of the sensor 4a from the detected surface of the main encoder body 24 is
adequately and certainly maintained, and thus it is possible to maintain the
reliability of the rotational speed detection.
[0032] Moreover, the inclination angle α1 of the generating line of the
nonxontact section 26a with respect to the center axis is preferably 10° to
45° , and more preferably 10° to 35°, and even more preferably 15° to 25°.
The closer the inclination angle α1 is to the most preferable range of 15° to
25°, the effect of preventing strain deformation in the axial direction of the
flat plate section 21 that exists in the portion of near the inner diameter of
the cover 19a. Moreover, by making the inclination angle α1 45° or less, the
occurrence of shear drop in the curved section between the cylindrical section
20 and the flat plate section 21 during processing is suppressed, and thus
variation in the starting point in the axial direction of the fitting section, and
the occurrence of peak fitting surface pressure due to the occurrence of shear
drop are also suppressed. Taking into consideration stability when
pressure fitting the cover 19a onto the outer ring 7, it is preferable that the
inclination angle α1 be a smaller value within the range above.

[0033] Preferably the outer-diameter dimension D24 of the main encoder
body 24 is less than the value that is obtained when the outer diameter D26
of the end section on the small-diameter side of the non-contact section 26a
(inside end section in the axial direction) is reduced by two times the plate
thickness t19 of the cover 19a (D24 < D26 - 2t19). In other words, preferably,
contact in the radial direction between the portion of the inner
circumferential surface of the non-contact section 26a and the outer
circumferential edge of the main encoder body 24 is prevented by regulating
the dimensions in the radial direction of each part in this way. More
preferably, the outer diameter D24 of the main encoder body 24 is less than a
value obtained when the outer diameter D26 of the end section on the
small-diameter side of the non-contact section 26a is reduced by three times
the plate thickness t19 of the cover 19a(D24 D26), so with the cylindrical section 20 of the cover 19b
fitted into the inside end section in the axial direction of the outer ring 7,
there is not contact between the inner circumferential surface of the outer
ring 7 and the outer circumferential surface of the non-contact section 26b.
In this example as well, the dimension L26 in the axial direction of the
non-contact section 26b is preferably two times or greater (L26 > 2t19) and five
times or less (L26 < 5t19) than the thickness dimension t19 of the plate
material of the cover 19b, and more preferably, L26 = (3 to 4) x t19. Moreover,
this dimension L26 in the axial direction is 50% or less than the length L19 in
the axial direction of the cover 19b (L26 < O.5L19), and is preferably 20% to

35% the length L19. The stepped section 27 is formed, after the partial
conical cylindrical section shown in the first example is formed, with the
rounded surface section on the inner-diameter side and the tapered surface
on the outer-diameter side between the partial conical cylindrical section and
the cylinder section 20 held, and with the rounded surface section on the
inner-diameter side between the partial conical cylindrical section and the
flat plate section 21 supported, by applying a punch from the inside of the
axial direction toward the partial conical cylindrical section. Therefore, as
in the first example, the occurrence of shear drop on the cylindrical section
side is suppressed. Furthermore, preferably the inclination angle α2 of the
common tangent line of the two rounded surface sections on the
outer-diameter side of the non-contact section 26b with respect to the center
axis is 10° to 45°, and more preferably 10° to 35°, and even more preferably,
15° to 25°. With the construction of this second example, the same function
and effects as in the first example are obtained.
[0035] In the rolling bearing unit with an encoder for supporting a wheel of
this present invention, including the first and second examples, a
non-contact section 26a, 26b that is provided for preventing straining of the
flat plate section 21, can be used to improve the seal performance of the
installation section of the cover 19a, 19b. In other words, as illustrated in
FIGS. 4A and 4B, it is possible to fill a sealing material 29 that is made using
an elastic material that includes an elastomer such as rubber or vinyl on the
outer circumferential surface of the non-contact section 26a, 26b so as to
cover the non-contact section 26a, 26b with this sealing material 29. The
outer diameter of this sealing material 29 in the free state is greater than
the inner diameter of the inside end section in the axial direction of the outer
ring 7. By holding this kind of sealing material 29 in an elastically
compressed state in the radial direction around the entire circumference
between the outer circumferential surface of the non-contact section 26a, 26b
and the inner circumferential surface of the inside end section in the axial
direction of the outer ring 7, it is possible to improve the seal performance of
the installation section. As this sealing material 29 is elastically
compressed, the force that applies inward in the radial direction to the flat

plate section 21 is limited, and by providing this sealing material 29,
harmful warping or strain does not occur in the flat plate section 21.
[0036] The seal of the installation section can also be maintained by filling
of the non-contact section 26a, 26b with sealant (caulking agent) such as a
gel instead of the seal material 29 having elasticity as described above. In
that case, after the cylindrical section 20 of the cover 19a, 19b has been fitted
into and fastened to the inside end section in the axial direction of the outer
ring 7, the sealant is filled into the gap 28. Moreover, after the outer
circumferential surface of the cylindrical section 20 has been coated with
sealant, it is possible to fit this cylindrical section 20 inside the outer ring 7.
Furthermore, it is also possible to maintain the seal of the installation
section by coating the surface of the cover 19a, 19b, including the outer
circumferential surface of the cylindrical section 20, with a coating film made
of a resin paint using electro deposition, and holding that film between the
outer circumferential surface of the cylindrical section 20 and the inner
circumferential surface of the inside end section in the axial direction of the
outer ring 7.
[0037]
[Example 3]
FIG. 5 illustrates a third example of an embodiment of the present
invention. In this example, a concave section 30 is formed in the center
section in the radial direction of the cover 19c. More specifically, the portion
further on the inside in the radial direction than the flat plate section 21 of
the cover 19c is caused to protrude to the outside in the axial direction
(internal space side). The detected surface of the main encoder body 24
faces the outside surface in the axial direction of the flat plate section 21
(surface on the internal space side). By providing this kind of concave
section 30, the rigidity of the flat plate section 21 is improved, and it becomes
possible to make the flat plate section 21 a more precise and better flat
surface. In this case as well, the inclination angle α1 of the non-contact
section is preferably 5° to 45°, and more preferably 10° to 35°, and most
preferably 15° to 25°. As a result, it becomes possible to fit and fasten the
cover 19c into the inside end section in the axial direction of the outer ring 7,

while better maintaining the flatness precision of the flat plate section 21.
The inner diameter of the flat plate section 21 is taken to be 25% or more the
diameter D19 of the cover 19c, and it is set within a range such that the
concave section 30 does not come in contact with the main encoder body 24 or
the like. Moreover, in consideration of the ease of processing and the
anti-deformation effect, the angle of the tapered surface of the concave
section 30 protruded from the flat plate section 21 to the outside in the axial
direction is regulated within the range 5° to 90°, and preferably 20° to 70°.
[0038]
[Example 4]
FIG. 6 illustrates a fourth example of an embodiment of the present
invention. In the case of the fourth example illustrated in FIG. 6, the
length in the axial direction on the inside end section in the axial direction of
the outer ring 7 from the inside surface in the axial direction of the
stationary side flange 10, is shorter than in the construction in the first
example illustrated in FIG. 1. In other words, in this example, the width of
the inside end section in the axial direction of the outer ring 7 is shortened,
and this outer ring 7 does not exist on the outside in the radial direction of
the non-contact section 26a of the cover 19a. In the case of the construction
of this example, the wedge shaped gap 28 (see FIG. l) that is formed between
the outer circumferential surface of the non-contact section 26a of the cover
19a and the inner circumferential surface of the inside end section of the
outer ring 7 is eliminated. Therefore, it is possible to prevent foreign
matter such as water being held in the portion of this gap 28 even when
there is no seal material 29 such as illustrated in the variation (see FIG. 4) of
the first and second examples, and thus it is possible to prevent foreign
matter such as water from getting inside the rolling bearing unit, and to
prevent rusting from occurring. It is also possible to use seal material
together with this construction. In that case, the seal material elastically
comes in contact around the entire circumference of the surface of part of the
outer ring 7, such as the inside end surface in the axial direction of the outer
ring 7.
[0039]

[Example 5]
FIG. 7 illustrates a fifth example of an embodiment of the present
invention. In the case of this fifth example illustrated in FIG. 7, the length
in the axial direction on the inside end section in the axial direction of the
outer ring 7 from the inside surface in the axial direction of the stationary
side flange 10 is longer than in the construction of the first example
illustrated in FIG. 1. In other words, in this example, the width of the
inside end section in the axial direction of the outer ring 7 is extended and
protrudes further inward in the axial direction than the flat surface section
21 of the cover 19a. In the case of the construction of this example, the
inside end section in the axial direction of the outer ring 7 that protrudes
inward in the axial direction serves the function of protecting the cover 19a,
and makes it possible to prevent pressing the cover 19a by mistake during
assembly, or deformation of the cover 19a due to hit by flying stones and the
like when the vehicle is traveling. Furthermore, because the sensor 4a is
also covered by the protruding end section in the axial direction of the outer
ring 7, the sensor 4a can be protected from dust, incoming stones and the like.
The construction of this example as well can easily be used together with
seal material, in which case the seal material elastically comes in contact all
the way around the outer circumferential surface of the inside end section in
the axial direction of the outer ring 7.
[0040]
[Example 6]
FIG. 8 illustrates a sixth example of an embodiment of the present
invention. In the case of this sixth example illustrated in FIG. 8, the length
in the axial direction on the inside end section of the outer ring 7 from the
inside surface in the axial direction of the stationary side flange 10 is a little
longer than in the construction of the first example illustrated in FIG. 1. In
other words, in this example, the width of the inside end section in the axial
direction of the outer ring 7 is extended a little, and protrudes just an
amount D inward in the axial direction more than the flat surface section 21
of the cover 19a. Moreover, with the outside end section in the axial
direction of the cylindrical section 20 facing the counterbore 32 of the outer

ring raceway 9 with a gap C remaining, the cylindrical section 20 is fitted
into and fastened to the inside end section in the axial direction of the outer
ring 7. Here, the outside surface (surface on the internal space side) in the
axial direction of the fiat plate section 21 and the detected surface of the
main encoder body 24 closely face each other through a gap A, and there is a
minute gap 25. On the other hand, with the detecting surface of the sensor
4a located inward in the axial direction by a gap B with respect to the inside
end in the axial direction of the outer ring 7, the sensor 4a is supported by
and fastened to the knuckle (not illustrated in the figure).
[0041] In the case of the construction of this example, gap A is set to be
larger than gap C (A > C). As a result, even when the cover 19a may be
pressed outward in the axial direction, the cover 19a does not come in
contact with the main encoder body 24. Furthermore, by having a gap B
and protruding amount D (B > 0, D > 0), there is a gap (B + D) between
opposing flat plate section 21 and detecting surface of the sensor 4a.
Therefore, even when the flat plate section 21 may vibrate or bulge due to a
rise in internal bearing pressure, the cover 19a and the sensor 4a do not
come in contact with each other, so it is possible to prevent fretting wear of
the detecting surface of the sensor 4a, and damage to the sensor element due
to that wear. The construction of this example can also easily be used
together with a seal material, and in that case the seal material elastically
comes in contact around the entire inner circumferential surface of the
inside end section in the axial direction of the outer ring 7. In the case of
use in a compact automobile, the gap A can be regulated to 0.5 ±0.1 mm, gap
B can be regulated to 0.1 ± 0.1 mm, gap C can be regulated to 0.25 ± 0.25 mm,
gap D can be regulated to 0.1 ± 0.1 mm, and the gap (B + D) between the
sensor 4a and the flat plate section 21 can be regulated to 0.2 ± 0.2 mm,
however the dimensions are not limited to this.
[0042]
[Example 7]
FIG. 9 and FIG. 10 illustrate a seventh example of an embodiment
of the present invention. In the seventh example illustrated in FIG. 9, the
construction differs from the construction of the first example illustrated in

FIG. 1 in that the main encoder body 24 of the encoder la is attached to the
inside surface in the axial direction of the circular ring section of a support
ring 23 that has an L-shaped cross section and an overall ring shape,
however, the length in the axial direction of the support ring 23 is small, and
an inner ring 12 of the hub 6 and a crimped section 13 of the main hub body
11 protrude further inward in the axial direction than the detected surface
(inside surface in the axial direction) of the main encoder body 24. In this
example, a convex section 31 is formed in the center section in the radial
direction of the cover 19d. More specifically, the portion on the inside in the
radial direction is made to protrude further to the inside in the axial
direction (external space side) than the flat plate section of the cover 19d.
The detected surface of the main encoder body 24 faces the outside surface in
the axial direction of the flat plate section 21 (surface on the internal space
side). By providing this kind of convex section 31, as in the third example of
the embodiment, it becomes possible to improve the rigidity of the flat plate
section 21 and make the flat plate section 21a flat surface having better
accuracy. The inner diameter of the flat plate section 21 is taken to be 25%
or greater than the diameter D19 of the cover 19d. Moreover, taking into
consideration the each of processing and the anti-deformation effect, the
angle of the tapered surface that protrudes from the flat plate section of the
convex section 31 to the inside in the axial direction is regulated to the range
of 5° to 90°, and preferably is regulated to the range of 20° to 70°.
[0043] In this example, the minute gap 25 (gap "a") between the outside
surface in the axial direction of the flat plate section 21 of the cover 19d
(surface on the internal space side) and the opposing detected surface of the
main encoder body 24 (inside surface in the axial direction) is set to be
greater than the gap "b" between the outside surface in the axial direction of
the flat plate section 21 and the inside surface in the axial direction of the
opposing inner ring 12 (a > b). As a result, even in the case where the cover
19d is pressed outward in the axial direction, the cover 19d comes in contact
at the portion (point d) of the flat plate section 21 of the cover 19d that is the
closest to the surface on the inside end in the axial direction of the inner ring
12, so the cover 19d does not come in contact with the main encoder body 24.

Moreover, in this example, the minute gap 25 (gap "a") is set to be greater
than the gap "c" between the outside surface in the axial direction of the
convex section 31 of the cover 19d and the surface on the inside end in the
axial direction of the crimped section 13 of the closely opposing main hub
body 11 (a > c). As a result, even in the case where the cover 19d is pressed
outward in the axial direction, the cover 19d comes in contact at the portion
(point "e") that is closest to the surface on the inside end in the axial
direction of the crimped section 13 of the convex section 31 of the cover 19d,
so the cover 19d does not come in contact with the main encoder body 24.
Taking into consideration the change in the relative inclination or
displacement of the outer and inner rings when a moment load is applied to
the bearing due to the reaction force of the road surface, and the precision of
the location of the pressure fit based on the outer ring7 when the encoder la
and the cover 19d is pressure fitted with the outer ring 7, the minimum
value of the gap "a" is regulated so that the main encoder body 24 and the
cover 19d do not come in contact.
[0044] In this example, gap "b" is set to be greater than gap V (b > c).
When the bearing is stationary, the effect of contact at point "d" and contact
at point "e" is the same, however, when the bearing is rotating, contact at
point "e" where the circumferential speed is lower is more preferable.
Therefore, in the present invention, the relationship of the sizes of these
gaps is regulated such that a > b > c, and is regulated such that when the
cover 19d is pressed outward in the axial direction, contact is first made at
point "e". The construction of this example can also be easily used together
with a seal material, and in that case, the seal material elastically comes in
contact all around the inner circumferential surface of the inside end section
in the axial direction of the outer ring 7 (see FIG. 10).
[0045] A characteristic of this example is that the amount that the fiat
plate section 21 moves in the axial direction when the cover 19d is pressed is
regulated by a gap in the axial direction that exists between the cover 19d
and the inside end surface in the axial direction of the hub 6 (crimped section
13 of the main hub body 11, or the inner ring 12). Therefore, by providing
gaps with the relationship (a > b, or a > c), an effect of avoiding contact

between the cover 19d and the main encoder body 24 is obtained. As a
result, in the case of an encoder la for which it is difficult to determine
possible problems due to the existence of the cover 19d, it is possible to
prevent a state in which the position of the encoder la moves due to contact
with the cover 19d and many electromagnetic signal errors occur. Moreover,
due to the effect of preventing this kind of contact, it is possible for the cover
and bearing to be closer than before, so it is possible to make the hub bearing
compact.
[0046] The present invention can be applied either to the case of the entire
surface of the flat plate section having a circular plate shape and extending
in the radial direction to the center section as in the first, second, fourth,
fifth and sixth examples, to the case of the cover having a concave section 30
formed in the center section as in the third example, or to the case of the
cover having a convex section 32 formed in the center section as in the
seventh example. Furthermore, the present invention can also be applied
to a case as disclosed in DE 19644744 (A1) where the cover has a circular
ring shape with a large circular hole in the center section for constructing a
rolling bearing unit with encoder for a drive wheel. Moreover, as far as
applicable, the characteristics of the examples can be applied to other
examples. For example, the construction of forming a concave section in the
center section of the third example, or the construction of forming a convex
section in the center section of the seventh example can be used instead of
construction comprising only the flat plate section above. In addition, it is
also possible to replace the construction of third and seventh examples by the
construction having only the flat plate section. Furthermore, it is possible
to apply the relationship between the outer ring and the cover of the first,
fourth and fifth examples to other examples, and to apply the regulation of
gaps described in the sixth and seventh examples to other examples.
[Experimental Example]
[0047] An example of a test that was performed in order to confirm the
effect of the present invention will be explained. In the test, the cover 19c of
the third example illustrated in FIG. 5 was used. The cover 19c was

manufactured using SUS304 stainless steel material having a thickness
dimension of t19 of 0.6 mm. The outer diameter D19 of this cover 19c was 57
mm, the length L19 in the axial direction was 7.8 mm, and the value of the
interference (absolute value of the difference between the inner diameter of
the inside end section in the axial direction of the outer ring 7 and the outer
diameter D19 of the cover 19c) was 0.18 mm (180 µm).
[0048] In this cover 19c, a partial conical convex surface section having a
dimension in the axial direction of 2.2 mm and an inclination angle of about
20° was formed. The cylindrical section 20 of this cover 19c was fitted into
the inside end section in the axial direction of the outer ring 7. In this state,
as a specified position near the outer diameter of the flat place section was 0,
the amount of transformation, which was the amount of expansion or
depression, of the portion of the flat plate section 21 that faces the detected
surface of the main encoder body 24 was measured using a dial gage, and as
a result the maximum value of deformation at this portion was 0.064 mm (64
urn). After that, the cover 19c was removed from the outer ring 7 and the
position of contact marks was checked, and when the dimension L26a in the
axial direction of the non-contact section was checked, the contact mark was
a little less than 2.2 mm, however two times or more (actually three times)
the plate thickness (0.6 mm) sufficiently remained.
[0049] As a comparison, a cover 19 having conventional construction was
manufactured under the same conditions at this example except that a
non-contact section was not provided, and the continuous section between
the cylindrical section 20 and the flat plate section 21 was continuous at a
bent section having a large curvature (the radius of curvature on the outer
diameter side in the free state before fitting inside the inside end section in
the axial direction of the outer ring 7 was a small 1.2 mm), and the
cylindrical section of this cover 19 was fitted into the inside end section in
the axial direction of the outer ring 7 that was the same as in the above
experimental example. Upon performing the same measurements, the
portion of the flat plate section 21 that faces the detected surface of the main
encoder body 24 deformed in the axial direction with the maximum value of
0.144 mm (144 µm). In other words, with the present invention, the amount

of deformation of the flat plate section of the cover, and particularly, the
portion of this flat plate section that faces near the main encoder body could
be suppressed by about 45% that of the conventional part, and through this
example, the effect of the present invention was confirmed.
[Industrial Applicability]
[0051] The rolling bearing unit with encoder for supporting a drive wheel
can be suitably applied to rotational support of a wheel.
[Explanation of Reference Numbers]
[0051]
1, la Encoder
2 Rolling bearing unit with encoder
3 Knuckle
4, 4a Sensor

5 Rolling bearing unit
6 Hub
7 Outer ring
8 Rolling element
9 Outer ring raceway
10 Stationary side flange
11 Main hub body
12 Inner ring
13 Crimped section
14 Inner ring raceway
15 Rotating side flange
16 Cage
17 Internal space
18 Seal ring
19, 19a, 19b, 19c, 19d Cover
20 Cylindrical section
21 Flat plate section
22 Shoulder section

23 Support ring
24 Main encoder body
25 Minute gap
26a, 26b Non-contact section
27 Stepped section
28 Gap
29 Seal material
30 Concave section
31 Convex section
32 Counterbore

CLAIMS
What is claimed is:
1. A rolling bearing unit with an encoder for supporting a wheel,
comprising:
an outer ring having double-row outer ring raceways around the
inner circumferential surface thereof, and that is supported by and fastened
to a suspension during use so as not to rotate;
a hub having double-row inner ring raceways around the outer
circumferential surface thereof, and with a wheel supported by and fastened
thereto during use, rotates together with the wheel;
rolling elements that are provided such that there are a plurality of
rolling elements located in each row between the outer ring raceways and
the inner ring raceways;
an encoder that is supported by and fastened to the hub so as to be
concentric with the hub, with the inside surface in the axial direction thereof
being a detected surface having a magnetic characteristic that alternately
changes in the circumferential direction; and
a cover that is made of a non-magnetic plate material, and that
comprises a cylinder section that extends in the axial direction, and a flat
plate section that is bent and extends inward in the radial direction from the
inside end section in the axial direction of the cylinder section, and together
with this cylinder section fitting into the inside end section in the axial
direction of the outer ring, the flat plate section closely facing the detected
surface of the encoder;
a non-contact section being formed all the way around the inside
end section in the axial direction of the cylinder section of the cover so as not
to come in contact with the inner circumferential surface of the outer ring
when the cover is fitted inside and fastened to the outer ring, and with the
cover fitted into the inside end section in the axial direction of the outer ring,
the cylinder section fitting into the inside end section in the axial direction of
the outer ring so that only the portion further on the outside in the axial

direction than the non-contact section fits inside with an interference fit.
2. The rolling bearing unit with an encoder for supporting a wheel
according to claim 1, wherein the non-contact section is formed into a partial
conical cylindrical shape that is inclined in a direction such that the
diameter becomes smaller going inward in the axial direction.
3. The rolling bearing unit with an encoder for supporting a wheel
according to claim 1, wherein the non-contact section is constructed by a
small-diameter stepped section with a stepped section being located between
the small-diameter stepped section and the portion near the outside in the
axial direction.
4. The rolling bearing unit with an encoder for supporting a wheel
according to claim 1, wherein the inside end surface in the axial direction of
the outer ring protrudes inward in the axial direction more than the inside
end surface of the flat plate section.
5. The rolling bearing unit with an encoder for supporting a wheel
according to claim 1, wherein a gap between the detected surface of the
encoder and the outside surface in the axial direction of the flat plate section
of the cover that faces the detected surface of the encoder is larger than a gap
between the outside end surface in the axial direction of the cylinder section
of the cover and an inside surface in the axial direction of a counterbore
which is formed further near the inside end in the axial direction than the
outer ring raceway of the outer ring and faces the outside end surface in the
axial direction of the cylinder section of the cover.
6. The rolling bearing unit with an encoder for supporting a wheel
according to claim 1, wherein a gap between the detected surface of the
encoder and the outside surface in the axial direction of the flat plate section
of the cover that faces the detected surface of the encoder is larger than a gap
between the inside end surface in the axial direction of the hub and the

outside surface in the axial direction of the cover that faces the inside end ,
surface in the axial direction of the hub..