SPECIFICATION
TITLE OF THE INVENTION
HUB UNIT BEARING
TECHNICAL FIELD
[0001] The present invention relates to a hub unit bearing for supporting the wheels of
an automobile so as to be able to rotate freely with respect to the suspension. More
specifically, the present invention relates to a hub unit bearing that comprises a cover
that, together with covering the inside end section in the axial direction of the outer ring
member and inner ring member and preventing foreign matter from entering inside,
has a water drain hole for discharging foreign matter that has entered inside to the
outside
BACKGROUND ART
[0002] Hub unit bearings comprising a rolling bearing unit are used for supporting the
wheels of an automobile so as to be able to rotate freely with respect to the suspension.
In recent years, rotational speed detectors for detecting the rotational speed of the
wheels have been installed into this kind of hub unit bearing, and control of anti-lock
brake systems (ABS) or traction control systems (TCS) is widely performed.
[0003] As an example of this kind of hub bearing unit with rotational speed detector, a
structure such as illustrated in FIG. 24 is disclosed in JP2005-090638. The hub unit
bearing with rotational speed detector of this first example of conventional construction
comprises a hub unit bearing 1 and a rotational speed detector 5, and the hub unit
bearing 1 comprises an outer ring member 2, a hub 3, which is an inner ring member,
and a plurality of balls 4, which are rolling elements.
[0004] The outer ring member 2 has a plurality of outer raceways 6 formed around the
inner circumferential surface thereof, and a stationary side flange 7 around the outer
circumferential surface. The outer ring member 2 corresponds to a stationary ring that
is supported by the knuckle (not illustrated in the figure) of the suspension and does not
rotate during operation.
[0005] The hub 3 is a combination of a main hub 8 and inner ring 9, and has a
plurality of inner raceways 10 formed around the outer circumferential surface, and is
supported on the inner diameter side of the outer ring member 2 such that it is
concentric with the outer ring member 2. A rotating side flange 11 for supporting the

wheel is formed on a portion of the outside end in the axial direction of the main hub 8,
that protrudes further outward in the axial direction than the opening on the outside
end in the axial direction of the outer ring member 2. Moreover, spline holes 13 for
making a spline fit with the drive shaft (not illustrated in the figure) that is fastened to
the surface on the outside end in the axial direction of an outer ring 12 of a constant
velocity joint is provided in the center section of the main hub 8. A plurality of balls 4
is located between each of the outer raceways 6 and the inner raceways 10 so as to be
able to roll freely. The outside in the axial direction is defined as the side toward the
outside in the width direction of the vehicle body when installed in the suspension, and
the inside in the axial direction is defined as the side that is near the center section in
the width direction of the vehicle body.
[0006] A seal ring 14 is provided between the opening section on the outside end in the
axial direction of the outer ring member 2 and the outer circumferential surface of the
middle section in the axial direction of the main hub 8. This seal ring 14 covers the
opening on the outside end in the axial direction of the rolling element installation space
15 where the balls 14 are located, and prevents grease that is inside this space 15 from
leaking to the outside, and prevents foreign matter on outside from entering into the
space 15. On the other hand, a combined seal ring 16 is provided between the portion
around the outer circumferential surface on the inside end section in the axial direction
of the inner ring 9 that is separated toward the inside in the axial direction away from
the inside inner raceway 10 that is formed around the inner ring 9 and the inner
circumferential surface on the inside end section in the axial direction of the outer ring
member 2, and covers the opening on the inside end in the axial direction of the space
15.
[0007] A cover 17 is fastened around the outside of the inside end section in the axial
direction of the outer ring member 2. This cover 17 is formed into a circular ring shape
by pressing metal plate, and a seal member 18 made using an elastic material is
attached around the inner edge of the inside end in the axial direction. The edges of
the tip ends of a plurality of seal lips that are formed on the seal member 18 come in
sliding contact all the way around the outer circumferential surface and stepped surface
on the outside end section in the axial direction of the outer ring 12 for a constant
velocity joint.
[0008] On the other hand, the rotational speed detector 5 comprises an encoder 19 and
sensor 20. The encoder 19 is such that the characteristics of the inside surface in the
axial direction, which is the detected surface, alternate at uniform intervals in the

circumferential direction, is supported and fastened such that it is concentric with the
hub 3 and rotates together with the hub 3. In the example in the figures, an encoder 19,
which is made using permanent magnets with the S-poles and N-poles alternating
around the inside surface in the axial direction, is attached and fastened to the inside
surface in the axial direction of the slinger 21 of the combined seal ring 16. Moreover,
the sensor 20 has a magnetic detecting element such as a Hall element or magnetic
resistance element that is provided in a detecting section, and is supported by and
fastened to the cover 17. In this state, the detecting section of the sensor 20 faces the
inside surface in the axial direction of the encoder 19. Furthermore, of a sensing space
22 that is located in the detecting section of the encoder 19 and the sensor 20 is such
that the opening on the inside end in the axial direction is covered by the seal member
18, and the opening on the outside end in the axial direction is covered by the combined
seal ring 16.
[0009] With the first example of conventional construction of a hub unit bearing 1, the
wheel that is fastened to the hub 3 can supported such that it rotates freely with respect
to the suspension the supports the outer ring member 2. Moreover, as the encoder 19
rotates together with the hub 3 as the wheel rotates, the N-poles and S-poles on the
detected surface of the encoder 19 alternate in passing the detecting section of the
sensor 20. As a result, the direction of the magnetic flux that flows in the magnetic
detection element of the sensor 20 changes, and the characteristic of this magnetic
detection element alternately changes. The frequency at which the characteristics of
the magnetic detection element changes in this way is proportional to the rotational
speed of the hub 3, so by sending the detection signal from the sensor 20 to a controller
(not illustrated in the figure), it is possible to perform suitable ABS or TCS control.
Furthermore, in the case of the first example of conventional construction, the sensing
space 22 can be closed off from the outside space by the seal member 18 that is attached
to the cover 17. Therefore, it is possible to prevent foreign matter such as sand or
small stones from entering in and biting in between the inside surface in the axial
direction of the encoder 19 and the detecting section of the sensor 20, and thus it is
possible to protect the encoder 19 and sensor 20 from the danger of damage. As a
result, the reliability of the rotational speed detection can be maintained, and suitable
ABS or TCS control is possible.
[0010] However, even in the case of the first example of conventional construction,
there is a possibility of moisture or minute particles entering into the sensing space 22
through a minute space between the seal member 18 and the outer ring 12 of the

constant velocity joint, or through a minute space between the cover 17 and the outer
ring member 2. Therefore, as the bearing is used over a long period of time, foreign
matter may accumulate inside the sensing space 22, which causes a drop in reliability of
the rotational speed detection.
[0011] For such a problem, as disclosed in JP2008-175382(A), JP2005-140320(A),
JP2005-331429(A) and JP2005-009525(A), the installation of a water drainage hole is
performed. FIG. 25 shows a second example of conventional construction of hub unit
bearing la which is disclosed in JP2008-175382(A). In the case of this second example
of conventional construction, a water drainage hole 23 is formed in the portion of a cover
17a that is fastened to the inside end section in the axial direction of the outer ring
member 2 that is located on the bottom end during operation. More specifically, the
cover 17a comprises a large-diameter cylindrical section 24 for fastening around the
inside end section in the axial direction of the outer ring member 2, a circular ring
shaped circular disk section 25 that is bent at a right angle toward the inside in the
radial direction from the inside end section in the axial direction of the large-diameter
cylindrical section 24, and a small-diameter cylindrical section 26 that is bent at a right
angle toward the inside in the axial direction from the inside end section in the radial
direction of the circular disk section 25. The water drainage hole 23 is formed in the
inner half section in the axial direction of the large-diameter cylindrical section 24 so as
to pass through the large-diameter cylindrical section 24, connecting the inside and
outside of the cover 17.
[0012] In this second example of conventional construction, foreign matter such as
moisture or minute particles that has entered into the sensing space 22 can be
discharged to the outside space through the water drainage hole 23. Therefore, it is
possible to prevent foreign matter from accumulating inside the sensing space 22, and
thus it is possible to maintain reliability of the rotational speed detection. It is omitted
in the figures, however, in the case of the construction of the invention disclosed in
JP2005-140320(A), JP2005-331429(A) and JP2005-009525(A) as well, a water drainage
hole is formed in the portion of the cover that is located at the bottom of the cover during
operation. Therefore, as in the case of the second example of conventional construction,
it is possible to discharge foreign matter that entered into the sensing space to the
outside space.
[0013] Incidentally, in any of the construction disclosed in JP2008-175382(A),
JP2005-140320(A), JP2005-331429(A) and JP2005-009525(A), including the second
example of conventional construction, the only intention for the water drainage hole is

to discharge foreign matter to the outside space, and preventing foreign matter from
entering from that outside space through this water drainage hole is not particularly
considered. In other words, when foreign matter such as water from a car wash, or
dirty water that is splashed on the vehicle during operation, much of that foreign matter
is comes near the cover 17 from underneath. As can be clearly seen in FIG. 25, a water
drainage hole 23 that is formed in the cover 17a is a simple hole that is formed in the
bottom section of the large-diameter cylindrical section 24, and as seen from the bottom
of the vehicle, the entire opening section of the water drainage hole 23 is exposed.
Consequently, it is easy for foreign matter such as dirty water to enter inside the cover
17a through this water drainage hole 23. Therefore, there is a possibility that the
reliability of rotational speed detection will drop due to foreign matter adhering to the
inside surface in the axial direction of the encoder and to the detecting section of the
sensor 20. Moreover, there is a possibility that the strength of the portion of the cover
17 which is fitted around the outer ring member 2 will decrease with location where the
water drainage hole 23 is formed.
[Related Literature]
[Patent Literature]
[0014]
[Patent Literature l] JP2005-090638(A)
[Patent Literature 2] JP2008-175382(A)
[Patent Literature 3] JP2005-140320(A)
[Patent Literature 4] JP2005-331429(A)
[Patent Literature 5] JP2005-009525(A)
SUMMARY OF THE INVENTION
[Problem to be Solved by the Invention]
[0015] In consideration of the problems above, the inventors attempted to improve the
construction of the water drainage hole that is formed in the cover as illustrated in FIG.
26 to FIG. 31. In this case, this bearing unit 1 comprises a cover 17b, a large-diameter
cylindrical section 27, a side wall section 28, a small-diameter cylindrical section 29, a
circular disk section 30 and an inner-diameter cylindrical section 31.
[0016] The large-diameter cylindrical section 27 is fitted and fastened around the end
section in the axial direction of the outer ring member 2. The side wall section 28 is

formed by bending from the inside end section in the radial direction of the
large-diameter cylindrical section 27 at a right angle inward in the radial direction, and
except for portions in the circumferential direction (the portions on the top end and the
bottom end in the operating state), the outside surface in the axial direction comes in
contact with the surface on the inside end in the axial direction of the outer ring
member 2. The small-diameter cylindrical section 29 is formed bending from the inside
end section in the radial direction of the side wall section 28 at a right angle inward in
the axial direction. The circular disk section 30 is formed by bending from the inside
end section in the axial direction of the small-diameter cylindrical section 29 at a right
angle inward in the radial direction. The inner-diameter cylindrical section 31 is
formed by bending from the inside end section in the radial direction of the circular disk
section 30 at a right angle outward in the axial direction, and is located on the inside in
the radial direction of the small cylindrical section 29
[0017] A bulging section 32 is formed by having the portion of the side wall section of
the cover 17b located on the bottom end in the operating state bulge inward in the axial
direction, and the water drainage hole 23a is formed in a state that passes through the
surfaces on both the inside and outside of this bulging section 32.
[0018] As illustrated in FIG. 28, in the case of this construction, even when the cover
17b is viewed from underneath the vehicle, the opening section of the water drainage
hole 23a is not exposed. Therefore, it becomes difficult for foreign matter such as dirty
water that is splashed during operation of the vehicle to enter inside the cover 17b.
Moreover, in the case of water drops that move in a spiral shape by riding on the wind
around the tire that is caused by the rotating tire as well, the side surface of the outer
perimeter of the bulging section 32 is covered, so it is difficult for foreign matter to enter
into the cover 17b. FIG. 29 illustrates construction wherein the side surfaces in the
circumferential direction of the bulging section 32 are raised at nearly right angles
inward in the axial direction, however, as the shape of this portion, by adopting inclined
surfaces which are inclined in a direction such that the width of the opening section
becomes narrow toward the inside in the axial direction as illustrated in FIG. 30 and
FIG. 31A, or curved surfaces as illustrated in FIG. 31B, the flow of air can be rectified so
as to further increase the effect of preventing water drops from entering.
[0019] However, in the case of this construction, it is necessary to form the bulging
section 32 on the cover 17b, so it is necessary to uses a highly ductile material as the
material for the cover 17b, which together with lower the freedom of material selection,
also increases the processing cost. Moreover, for a cover 17b made using a highly

ductile material, there is a problem in that it is not possible to sufficiently maintain the
strength of the fit with the outer ring member 12. Therefore, practical implementation
of this construction is considered to be difficult.
[0020] Therefore, the object of the present invention is to provide construction of a
cover in a hub unit bearing that has no problem with the strength of the fit with the
outer ring member, and together with being able to suppress foreign matter such as
dirty water from entering inside, is also able to easily discharge foreign matter that has
entered inside.
[Means for Solving the Problems]
[0021] The hub unit bearing of the present invention comprises: an outer ring member,
which is a stationary ring; an inner ring member, which is a rotating ring that can
rotate relative to the outer ring member via a plurality of rolling elements; and a cover
that covers the inside end sections in the axial direction of the outer ring member and
inner ring member. More specifically, the outer ring member has a plurality of rows of
outer raceways formed around the inner circumferential surface, and during operation,
is a stationary ring that is supported by the suspension and does not rotate; the inner
ring member has a plurality of rows of inner raceways formed around the outer
circumferential surface, is located on the inner-diameter side of the outer ring member
such that it is concentric with the outer ring member, comprises a flange that is formed
around the outside end section in the axial direction and supports the wheel, and during
operation is a rotating ring that rotates together with the wheel; the plurality of rolling
elements are located in each row between both the outer raceway and the inner raceway,
such that they can roll freely; and with this construction it is possible to support the
inner ring member such that it can rotate freely. The present invention can be applied
to both the unit for drive wheel and for follower wheel.
[0022] In the hub unit bearing of a first aspect of the present invention, the cover has
a disk section, and a cylindrical section that is bent outward in the axial direction from
the outer perimeter edge section of the disk section, and is fitted with and fastened to
the outer ring member. The cylindrical section comprises a cut and raised section that
is formed in part in the circumferential direction of the cylindrical section by being cut
and raised toward the inside or outside in the radial direction of the cylindrical section,
such that this cut and raised section forms a water drainage hole that passes through
from the inside to the outside of the cover.
[0023] The cut and raised section can be cut and raised by cutting two cutting-plane

lines along the circumferential direction of the cylindrical section. In this case, water
drainage holes can be formed on both sides in the axial direction of the cut and raised
section.
[0024] The cut and raised section can also be cut and raised by cutting one
cutting-plane line along the circumferential direction of the cylindrical section. In this
case, one side in the axial direction of the cut and raised section is continuous with the
cylindrical section, and the water drainage hole is formed on the other side in the axial
direction. In this case, except for both sides in circumferential direction that are
continuous with the cylindrical section, the cut and raised section can have an L-shaped
cross section or a linear shaped cross section in the cross section in the axial direction of
the cover (cross section in a virtual plane that includes the center axis of the cover).
[0025] In the hub unit of a second aspect of the present invention as well, the cover
comprises a disk section, and a cylindrical section that is bent outward in the axial
direction from the perimeter edge section of the disk section, and is fitted with and
fastened to the outer ring member. In this second aspect, comprises a groove section
that is recessed toward the inside or the outside in the radial direction along the axial
direction, and a water drainage hole that passes through from the inside to the outside
of the cover is formed in the portion between the groove section and the outer ring
member.
[0026] The groove section is formed in the cylindrical section such that the groove
section is parallel with the axial direction of the cover. Alternatively, the groove section
is formed in the cylindrical section such that the groove section is inclined with respect
to the axial direction of the cover.
[0027] In the hub unit bearing of a third aspect of the present invention as well, the
cover has a disk section, and a cylindrical section that is bent outward in the axial
direction from the perimeter edge section of the disk section, and is fitted with and
fastened to the outer ring member. In this third aspect, the cylindrical section
comprises at least: a large-diameter cylindrical section that is fitted onto and fastened to
the inside end section in the axial direction of the outer ring member.' a side wall section
that is bent inward in the radial direction from the inside end section in the axial
direction of the large-diameter cylindrical section, with the outside surface in the axial
direction thereof coming in contact with the surface on the inside end in the axial
direction of the outer ring member,' and a small-diameter cylindrical section that is
continuous with the disk section and is bent inward in the axial direction from the
inside end section in the radial direction of the side wall section.

[0028] A water drainage hole is formed in the portion in part in the circumferential
direction of the cylindrical section that connects the small-diameter cylindrical section
and the side wall section. Moreover, the bottom end section of the water drainage hole
located in the middle section in the radial direction of the side wall section and is located
further downward then the bottom end section of the inner circumferential surface of
the inside end section in the axial direction of the outer ring member.
[0029] In the hub unit bearing of a third aspect of the invention as well an
inner-diameter cylindrical section is bent outward in the axial direction from the inside
end section in the radial direction of the disk section,' wherein the inner circumferential
surface of the inner-diameter cylindrical section functions as a seal surface with which
the edge on the tip end of the seal member made of elastic material, which is a seal that
is provided between the cover and the inner ring member or separate member (for
example the outer ring for a constant velocity joint) that rotates together with the inner
ring member, comes in sliding contact or closely faces all around in the circumferential
direction.
[0030] In any of the aspects of the present invention, during operation, the water
drainage hole can located in the portion of the cover located at the bottom portion, and
more specifically, can be located within a range of+35° in the circumferential direction
with an intersection point where a plumb line that passes through the center axis of the
cover crosses the bottom end section of the cover.
[0031] In both the first aspect and second aspect of the present invention, the
cylindrical section can be constructed so as to comprise a large-diameter cylindrical
section that is fitted and fastened around the outside or inside of the inside end section
in the axial direction of the outer ring member; a side wall section that is bent inward in
the radial direction from the inside end section in the axial direction of the
large-diameter cylindrical section, the outside surface in the axial direction thereof
coming in contact with the surface on the inside end in the axial direction of the outer
ring member; or a flange section that protrudes outward in the radial direction from the
inside end section in the axial direction of the large-diameter cylindrical section, and is
bent inward in the radial direction, the outside surface in the axial direction thereof
coming in contact with the surface on the inside end in the axial direction of the outer
ring member; and a small-diameter cylindrical section that is bent inward in the axial
direction from the side wall section or the flange section. In this case, in the first
aspect of the invention, the cut and raised portion can be formed in the small-diameter
cylindrical section. In the second aspect of the invention, the groove section can be

formed in the large-diameter cylindrical section.
[0032] In all of the aspects of the present invention, the disk section includes, for
example, a disk shaped member that is employed in the case of a hub unit bearing for a
follower wheel and that covers the entire radial direction on the inside end in the axial
direction, and, for example, a circular ring shaped member that is employed in the case
of a hub unit bearing for a drive wheel, and that closes off the space between the outer
ring member and the outer ring for a constant velocity joint. In the case of the latter, a
seal member made of an elastic material can be provided on the inside end section
(inner perimeter edge section) in the radial direction, and the edge on the tip end of the
seal lip of the seal member can come in sliding contact all the way around the outer
circumferential surface of the inside end section in the axial direction of the inner ring
member, or the outer circumferential surface on the outside end section in the axial
direction or the step surface of the outer ring for the constant velocity joint,
[0033] Furthermore, in the case of the hub unit bearing of any of the aspects of the
invention, construction capable of detecting the rotation of the inner ring member is
possible, wherein an encoder is provided on the outer circumferential surface of the
inside end section in the axial direction of the inner ring member, which is a rotating
ring, and a sensor having a detecting section that faces the encoder is provided in part of
the cylindrical section or disk section of the cover.
[Effect of the Invention]
[0034] With the hub unit bearing of the present invention, having the construction
described above, it is possible to maintain the strength of the fit of the cover with the
outer ring member, and it is possible to achieve construction that makes it difficult for
foreign matter such as muddy water to enter through a water drainage hole that is
formed in the cover, as well as makes it possible for foreign matter to drain without
building up inside the internal space.
[0035] In other words, in the case of the first aspect of the hub unit bearing, a water
drainage hole that passes from the inside to the outside of the cover is formed in the
cylindrical section of the cover by a cut and raised section that is formed by cutting and
raising part of the cylindrical section in the radial direction. Part of the cut and raised
section of this kind of water drainage hole is connected with the cylindrical section, so
the strength of the cylindrical section is maintained. Therefore, it is possible to
maintain the strength of the fit of the cover with the outer ring member. Moreover,
when the cover is viewed from underneath (outside in the radial direction) the vehicle,

the water drainage hole is not exposed (the water drainage hole is not open directly to
the outside), so it is possible to effectively prevent foreign matter such as water from
entering inside the cover through the water drainage hole.
[0036] In the case of the hub unit bearing of the second aspect of the present invention
a concave groove section is formed along the axial direction of the cylindrical section of
the cover, and a tunnel shaped water drainage hole is formed between this groove
section and the outer ring member. Consequently, the water drainage hole can be
formed without having to cut the cylindrical section. Therefore, it is possible to
maintain the strength of the cylindrical section, and thus it is also possible to maintain
the strength of the fit of the cover with the outer ring member. Moreover, when the
cover is viewed from underneath (outside in the radial direction) the vehicle, the water
drainage hole is not exposed, so it is possible to effectively prevent foreign matter such
as water from entering inside the cover through the water drainage hole. Furthermore
there is no cut surface through the cover, so it is not necessary to perform masking when
performing rust proofing process such as coating of the cover, so rust proofing can be
performed easily, and thus the cover can have excellent rust proof characteristics.
[0037] In the case of the hub unit bearing of a third aspect of the present invention,
the water drainage hole is formed in the portion that connects the small-diameter
cylindrical section and the side wall section of the part of the cover that is located at the
bottom during operation, with the bottom section of the portion that is opened in the
side wall section being located in the middle section in the radial direction of the side
wall section so as not to lead to the outer perimeter section. Therefore, when the cover
is viewed from underneath the vehicle, the portion of the water drainage hole that is
opened into the side wall section is not exposed. As a result, it becomes difficult for
foreign matter such as muddy water that is splashed up while the vehicle is traveling to
enter through the opening in the side wall side into the internal space (sensing space)
where, for example, the encoder or detecting section of the sensor are located.
[0038] Moreover, there is an inner-diameter cylindrical section of the cover that is
located inward in the radial direction of the portion of the water drainage hole that is
opened into the small-diameter cylindrical section of the cover, so foreign matter that
enters in from the opening in the small-diameter section is thrown back by the outer
circumferential surface of this inner-diameter cylindrical section, or after matter has
adhered to the outer circumferential of this inner-diameter cylindrical section, the
matter drips down and is drained to the outside. Therefore, it becomes difficult for
foreign matter such as dirty water to enter inside the internal space through the

opening in the small-diameter cylindrical section. In this third aspect of the present
invention, it is possible in this way to keep foreign matter from entering inside the
internal space through the water drainage hole.
[0039] Furthermore, the bottom end section of the water drainage hole that is opened
into the side wall section is located further downward than the bottom end section of the
inner circumferential surface of the inside end section in the axial direction of the outer
ring member, so it is possible to effectively prevent foreign matter from building up
between the inner circumferential surface on the inside end section of the outer ring
member and the outside surface in the axial direction of the side wall section, and by
taking advantage of force of gravity, it is possible for foreign matter to efficiently drain
to the outside space.
[0040] In this construction, it is not necessary to form a bulge section for forming a
water drainage hole in part of the cover, so together with being able to prevent a
reduction in freedom of the selection of material for the cover, it is possible to prevent an
increase in processing costs. Moreover, the cover can be fitted and fastened to the outer
ring member with sufficiently large strength.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is a cross-sectional view of a first embodiment of a hub unit bearing of
the present invention.
FIG. 2 is an enlarged view of A in FIG. 1.
FIG. 3 is a cross-sectional view of section I-I of the cover illustrated in FIG. 2.
FIG. 4 is an enlarged perspective view of a water drainage hole in the cover
illustrated in FIG. 2.
FIG. 5 is a schematic drawing illustrating the phase of the water drainage hole.
FIG. 6 is an enlarged cross-sectional view of the major parts of a first variation
of the cover of the first embodiment of the present invention.
FIG. 7 is an enlarged cross-sectional view of the major parts of a second
variation of the cover of the first embodiment of the present invention.
FIG. 8 is an enlarged cross-sectional view of the major parts of a third variation
of the cover of the first embodiment of the present invention.
FIG. 9 is an enlarged cross-sectional view of the major parts of a fourth
variation of the cover of the first embodiment of the present invention.
FIG. 10 is an enlarged cross-sectional view of the major parts of a fifth
variation of the cover of the first embodiment of the present invention.

FIG. 11 is a cross-sectional view illustrating a second embodiment of the hub
unit bearing of the present invention.
FIG. 12A is a bottom view of the cover illustrated in FIG. 11, and FIG. 12B is a
left side view of the cover illustrated in FIG. 11.
FIG. 13 is a bottom view illustrating a variation of the cover of this second
embodiment.
FIG. 14 is an enlarged cross-sectional view of the major parts of a third
embodiment of the hub unit bearing of the present invention.
FIG. 15 is a cross-sectional view of a fourth embodiment of the hub unit bearing
of the present invention.
FIG. 16 is an enlarged view of B in FIG. 15.
FIG. 17 is a cross-sectional view illustrating a removed cover and sensor of the
fourth embodiment.
FIG. 18 is a view as seen from the right in FIG. 17.
FIG. 19 is a view of the cover as seen from the bottom in FIG. 18.
FIG. 20 is a perspective view illustrating the portion near the bottom end of the
cover.
FIG. 21 is a drawing similar to FIG. 20, and illustrates a first variation of the
fourth embodiment of the present invention.
FIG. 22 is a drawing similar to FIG. 16, and illustrates a second variation of the
fourth embodiment of the present invention.
FIG. 23 is a cross-sectional view illustrating the state of performing a grinding
process of the outer surface of the inner ring.
FIG. 24 is a cross-sectional view illustrating a first example of conventional
construction of a hub unit bearing.
FIG. 25 is a cross-sectional view illustrating a second example of conventional
construction of a hub unit bearing.
FIG. 26 is a cross-sectional view illustrating a hub unit bearing of a prior
invention.
FIG. 27 is a drawing of a removed cover and sensor as seen from the right side
in FIG. 26.
FIG. 28 is a drawing of the cover as seen from the bottom in FIG. 27.
FIG. 29 is a perspective view illustrating the portion near the bottom end of the
cover.
FIG. 30 is a drawing that corresponds to FIG. 29, and illustrates a devised

shape of the portions on both sides in the circumferential direction of the water drainage
hole of the bulge section of the cover.
FIG. 31 is a cross-sectional view illustrating a second example of the portions
on both sides in the circumferential direction of the water drainage hole.
ILLUSTRATIVE EMBODIMENTS FOR CARRYING OUT THE INVENTION
[Embodiment l]
[0042] FIG. 1 to FIG. 10 illustrate a first embodiment of a hub unit bearing of the
present invention. The hub unit bearing 33 of this embodiment is a hub unit bearing
unit for a drive wheel, and as illustrated in FIG. 1, comprises an outer ring member 34,
a hub 35 as an inner ring member, a plurality of balls 36 as rolling elements, seals 37a,
37b, an rotational speed detector 38 and a cover 39.
[0043] The outer ring member 34 is a stationary ring and is fastened inside a retaining
hole 41 of a knuckle 40 that is fastened to the vehicle (not illustrated in the drawings),
and by connecting a stationary-side flange 42 that is formed around the outer
circumferential surface of the outer ring member 34 to the knuckle 40 using bolts 43,
the outer ring member 34 is connected and fastened to the knuckle 40.
[0044] The hub 35 is a rotating ring and is an integrated combination of a main hub 44
and a separate inner ring 45, and this hub 35 is supported on the inner diameter side of
the outer ring member 34 such that it is concentric with the outer ring member 34.
The main hub 44 is a circular column shaped member having a rotating-side flange 46
that is formed around the outer circumferential surface of the outside end in the axial
direction (left end in FIG. l) such that it extends outward in the radial direction from
the outer circumferential surface. Hub bolts 47 for connecting to the wheel and brake
rotor (not illustrated in the drawings) are implanted in the rotating-side flange 46 such
that they are evenly spaced around the circumferential direction. Spline holes 48 for
making a spline fit with the spline shaft of a constant velocity joint (not illustrated in
the drawings) are formed on the inner circumferential surface of the main hub 44.
[0045] A small-diameter stepped section 49 is formed around the inside end (right side
in FIG. l) in the axial direction of the main hub 44. An inner ring 45 is fitted onto this
small-diameter stepped section 49, after which the inner ring 45 is connected and
fastened to the main hub 44 by crimping the end section in the axial direction of the
small-diameter stepped section 49. By pressing the inner ring 45 with this crimping,
proper pre-loading is applied to the balls 36.
[0046] Double rows of outer raceways 50a, 50b that are parallel with each other in the

axial direction are formed around the inner circumferential surface of the outer ring
member 34. Moreover, inner raceways 51a, 51b are respectively formed around the
outer circumferential surfaces of the main hub 44 and the inner ring 45 such that they
correspond with the outer raceways 50a, 50b of the outer ring member 34. Balls 36 are
located in the raceways that are formed by the inner raceways 51a, 51b and the outer
raceways 50a, 50b, and are held by a retainer 52 so that they are evenly spaced in the
circumferential direction and so that they can roll freely
[0047] These balls 36 come in contact with the outer raceways 50a, 50b and inner
raceways 51a, 51b at specified angles with each other to form a back-to-back duplex
bearing (DB). As a result, the main hub 44 is able to rotate around the center axis (CL)
of the outer ring member 34.
[0048] A seal 37a is provided between the opening section on the outside end in the
axial direction of the outer ring member 34 and the outer circumferential surface in the
middle section in the axial direction of the main hub 44. On the other and, a seal 37b is
provided between the opening section on the inside end in the axial direction of the
outer ring member 34 and the outer circumferential surface of the inner ring 45. These
seals 37a, 37b seal both end sections in the axial direction of the rolling element
installation space 53 where the balls 36 of the hub unit bearing 33 are located, and
together with preventing grease in this space from leaking out, prevent various foreign
mater such as rain water, mud, dust and the like on the outside from entering inside the
rolling element installation space 53.
[0049] The seal 37b comprises a metal core 55 having an L-shaped core that is
pressure fitted into and fastened to the inner circumferential surface 54 on the inside
end section in the axial direction of the outer ring member 34, an elastic seal section 56
that is formed using rubber and the like and is fastened to the core 55, and a slinger 59
that is pressure fitted around and fastened to the outer circumferential surface 57 of the
inner ring 45 and comes in sliding contact with three seal lips 58 of the elastic seal
section 56.
[0050] The rotational speed detector 38 comprises an encoder 60 and a sensor 61.
The encoder 60 is attached and fastened to the side surface of the slinger 59. Moreover,
the sensor 61 is located such that the detecting section 62 thereof is close to the detected
surface 63 of the encoder 60. The encoder 60 is a rubber magnet or plastic magnet, in
which a ferromagnetic material such as ferrite or rare-earth element is mixed inside
rubber or synthetic resin, and is formed into a circular ring shape and magnetized.
The magnetization direction alternately changes at equal intervals in the

circumferential direction.
[0051] The cover 39 has a circular disk section 65 that is formed by pressing metal
plate that is rust proof such as stainless steel plate or galvanized steel plate, and has a
through hole 64 though which a spline shaft of a constant velocity joint (not illustrated
in the drawings) passes through, and a small-diameter cylindrical section 66 and
large-diameter cylindrical section 67 that are formed by bending the outer perimeter
edge section of the circular disk section 65 outward in the axial direction in two stages.
The large-diameter cylindrical section 67 fits around the outer circumferential surface
68 of the inside end section in the axial direction of the outer ring member 34, and the
stepped section 69, which connects the small-diameter cylindrical section 66 and the
large-diameter cylindrical section 67, is brought into contact with the surface 70 on the
inside end in the axial direction of the outer ring member 34.
[0052] As illustrated in FIG. 2 to FIG. 4, a cut and raised section 71 is formed in the
small-diameter cylindrical section 66. This cut and raised section 71 is formed by
cutting two cutting-plane lines that are parallel along the circumferential direction of
the small-diameter cylindrical section 66, and raised toward the inside in the radial
direction of the small-diameter cylindrical section 66. The cut and raised section 71 is
also cut and raised in a band shape from small-diameter cylindrical section 66 so as to
have a trapezoidal cross-sectional shape where both end sections in the circumferential
direction of the cut and raised sections 71 are continuous with the small-diameter
cylindrical section 66, and both side sections in the axial direction of the cut and raised
section 71 are separated from (detached from) the small-diameter cylindrical section 66.
As a result, a water drainage hole 73 that passes through from the inside to the outside
of the cover 39 is formed on both sides in the axial direction of the cut and raised section
71.
[0053] The sensor 61 is inserted through a sensor hole that is formed in the
small-diameter cylindrical section 66 of the cover 39, and the detecting section 62 of the
sensor 61 is located so as to face the detected surface 63 of the encoder 60. As the
encoder 60 rotates together with the main hub 44 and inner ring 45, the output from the
sensor 61 changes at a frequency that is proportional to the rotational speed, and the
rotational speed of the wheel (not illustrated in the drawings) is detected.
[0054] As illustrated in FIG. 5, preferably a water drainage hole 73 is located at
position D in the bottom end section of the cover 39, and position Al within a range of
10° to 35° in the circumferential direction of rotation when the vehicle is travelling
forward from the intersection point where a vertical line VL passes through the center

axis of the cover 39. Here, position I) is a position where water can drain easily due to
gravity when the vehicle is stopped, and position Al is position where water that is
splattered by the rotation of the encoder 60 can drain.
[0055] Normally, a vehicle travels in the forward direction the majority of the time, so
forming the water drainage holes 73 at position D and Al as described above is suitable,
however, when, for convenience of manufacturing or management, the cover 39 is made
to be used by either the left or right wheel and it is not possible to specify the direction of
rotation, a third water drainage hole 73 could also be located at a position A2 that is
axially symmetrical to position Al with respect to the vertical line VL. The number of
water drainage holes 73 is arbitrary, and it is also possible to have four or more.
[0056] Furthermore, in the case of a bearing that is used in a normal passenger
vehicle or a freight vehicle, preferably the water drainage holes are located at a total of
two positions, position D and at a position 6° to 12° in the direction of rotation from the
vertical line VL when the vehicle is traveling in the forward direction. Here, the
reason for the angle being 6° to 12° is that on a good flat and paved road the
acceleration/deceleration of an automobile that is being driven safely within the legal
speed limit is normally 0.1G to 0.2 G, so the tangent (tan) of the acceleration and gravity
is within the range 0.1 to 0.2.
[0057] In the case of a vehicle that often travels over poor roads, when taking the
instantaneous acceleration/deceleration or orientation of the vehicle into consideration,
a position at a larger angle, for example 20° to 30° is preferred, and in the case of a
vehicle that is used for construction or farming, or a 4-wheel drive vehicle, the vehicle
often travels forward or backward at low speed over uneven terrain, so preferably water
drainage holes are used at a total of three location, position D above, and one location at
a position 10° to 25° on both sides in the circumferential direction from the vertical line
VL. Furthermore, when the water drainage hole is located at an angle 6° to 12°, it is
also possible to form one elongated water drainage hole instead of a plurality of holes.
[0058] Moreover, as illustrated in FIG. 3, the length (L) in the circumferential
direction of each water drainage hole 73 is preferably 4 to 10 times the raw material
plate thickness (t). This is because when the length (L) in the circumferential direction
is less than 4 times the plate thickness (t), the cutting and raising process is difficult,
and when the length (L) is greater than 10 times the plate thickness (t), the rigidity of
the small-diameter cylindrical section 66 decreases due to the cut and raised section 71,
and together with being difficult to maintain a proper slit width, there is a possibility
that the strength of the small-diameter cylindrical section will be affected.

Furthermore, when water drainage holes are formed at a plurality of locations, from the
aspect of strength, preferably the total of the lengths (L) of the water drainage holes 73
is 5% to 10% the length of the outside perimeter of the small-diameter cylindrical
section.
[0059] As illustrated in FIG. 3, the height (H) of a water drainage hole 73 is arbitrary,
however preferably is 0.5 mm or greater and is equal to or less than the plate thickness
(t). This is because when the height (H) is less than 0.5 mm, there is possibility that
water will not sufficiently drain due to interfacial tension of water, and when the height
(H) is greater than the plate thickness (t), not only is processing difficult, the area of the
opening of the water drainage hole 73 becomes large and possibility that foreign matter
will enter through the hole increases. In FIG. 3, in order to more easily understand the
construction of the water drainage hole 73, the height (H) of the water drainage hole 73
is represented as being larger than the plate thickness (t).
[0060] Furthermore, as illustrated in FIG. 2, the width (W) in the axial direction of the
cut and raised section 71 is preferably at least 2 times the plate thickness (t). For the
same reason as described above, preferably the space (C) between the surface on the
inside end in the axial direction of the cut and raised section 71 and the inside surface of
the disc section 65 is at least 2 times the plate thickness (t). When the space (C) is too
small, there is a possibility that water will not sufficiently drain due to interfacial
tension of water. In FIG. 2, in order to more easily understand the construction of the
cut and raised section 71, the space (C) is represented as being smaller than 2 times the
plate thickness (t).
[0061] The material of the cover 39 is preferably a non-magnetic material such as an
austenitic stainless steel. In the case of an austenitic stainless steel, the cut and raised
section can be formed by pressing, and the material does not hold abrasive powder that
is magnetized by receiving a mechanical force, and does not attract and hold iron sand
or dust from the road with a magnetic force. Moreover, the shape of the cut and raised
section 71 is arbitrary, and is not limited to having a trapezoidal cross-sectional shape
as illustrated in FIG. 3; for example, it could also having a triangular or arc shaped
cross-sectional shape.
[0062] As was explained above, with the hub unit bearing 33 of this embodiment, it is
possible for foreign matter such as water that entered inside the cover 39 to effectively
drain from the water drainage holes 73 that are formed in the bottom section of the
cover 39. Moreover, in the case of the hub unit bearing 33 of this embodiment, the
portions (the both ends in the circumferential direction) of the cut and raised sections 71

for forming the water drainage holes 73 that/pass through from the inside to the outside
of the cover are connected to the small-diameter cylindrical section 66, so the strength of
the small-diameter cylindrical section 66 is maintained. Therefore, with the cover 39
having this kind of construction, it is possible to maintain the strength of the fit with the
outer ring member 34.
[0063] Furthermore, the shape of the water drainage hole 73 differs from the shape of
a conventional water drainage hole, and when viewed from the bottom (outward in the
radial direction) of the cover 39, the front surface of the opening is covered by the band
shaped cut and raised section 71 such that the opening portion of the water drainage
hole is not exposed (the water drainage hole 73 is not directly open to the outside), so it
is possible to effectively prevent foreign matter such as water from entering inside the
cover 39.
[0064]
[Embodiment 1, Variation l]
FIG. 6 illustrates a first variation of this first embodiment of the present
invention. A cover 39A as illustrated in FIG. 6 can also be used as the cover to cover
the inside end sections in the axial direction of the outer ring member 34 and hub 35.
This cover 39A does not have a small-diameter cylindrical section, but only a
large-diameter cylindrical section 67, and a cut and raised section 71 that is formed in
the large-diameter cylindrical section 67 is formed so as to protrude toward the inside in
the radial direction. The cover 39A is assembled so that the tip end section (outside
end section in the axial direction) of the large-diameter cylindrical section 67 fits around
the outer circumferential surface 68 of the outer ring member 34, and the surfaces on
the outside end in the axial direction (surface on the left end) of the cut and raised
section 71 comes in contact with the surface 70 on the inside end of the outer ring
member 34.
[0065] With this variation, of the two water drainage holes 73 that are formed on both
sides in the axial direction of the cut and raised section 71, one of the water drainage
holes 73 (left side in FIG. 6) is covered by the outer ring member 34, so it is possible to
effectively prevent foreign matter such as water from entering inside the cover 39A.
[0066]
[Embodiment 1, Variation 2]
FIG. 7 illustrates a second variation of the first embodiment of the present
invention. It is also possible to used a cover 39B such as illustrated in FIG. 7 as the
cover that covers the inside end sections in the axial direction of the outer ring member

34 and the hub 35. In this cover 39B, a cut and raised section 71 is formed so as to
protrude toward the outside in the radial direction, and water drainage holes 73 are
formed in the portions on both sides in the axial direction of the cut and raised section
71.
[0067]
[Embodiment 1, Variation 3]
FIG. 8 illustrates a third variation of the first embodiment of the present
invention. It is also possible to uses a cover 39C such as illustrated in FIG. 8 as the
cover that covers the inside end sections in the axial direction of the outer ring member
34 and the hub 35. This cover 39C is such that part of the small-diameter cylindrical
section 66 is cut with one cutting-plane line 72C along the circumferential direction at a
location near the disk section 65, and by raising that portion toward the inside in the
radial direction, a cut and raised section 71C having an L-shaped cross section
(crank-shaped cross section) is formed in the small-diameter cylindrical section 66.
Therefore, the outside in the axial direction (left side in FIG. 8) of the cut and raised
section 71C is continuous with the small-diameter cylindrical section 66, and the inside
in the axial direction (right side in FIG. 8) is detached from the small-diameter
cylindrical section 66, and a water drainage hole 73 is formed in the detached portion.
[0068] With this variation, the water drainage hole 73 is only formed on the inside in
the axial direction of the cut and raised section 71C (right side in FIG. 8), so when
compared with the case wherein holes are formed on both sides in the axial direction, it
is possible to further prevent foreign matter such as water from entering inside the
cover 39C.
[0069]
[Embodiment 1, Variation 4]
FIG. 9 illustrates a fourth variation of this first embodiment of the present
invention. It is also possible to use a cover 39D such as illustrated in FIG. 9 as the
cover that covers the inside end sections in the axial direction of the outer ring member
34 and hub 35. This cover 39D is such that part of the small-diameter cylindrical
section 66 is cut with one cutting-plane line 72D along the circumferential direction at a
location near the disk section 65, and by raising that portion toward the inside in the
radial direction, a cut and raised section 71D having linear cross section is formed in the
small-diameter cylindrical section 66 such that it extends diagonally upward toward the
inside in the axial direction from the small-diameter cylindrical section 66. Therefore,
the outside in the axial direction (left side in FIG. 9) of the cut and raised section 71D is

continuous with the small-diameter cylindrical section 66, and the inside in the axial
direction (right side in FIG. 9) is detached from the small-diameter cylindrical section
66, and a water drainage hole 73 is formed in the detached portion.
[0070] With this variation, the water drainage hole 73 is only formed on the inside in
the axial direction of the cut and raised section 71D (right side in FIG. 9), so when
compared with the case wherein holes are formed on both sides in the axial direction, it
is possible to further prevent foreign matter such as water from entering inside the
cover 39D.
[0071]
[Embodiment 1, Variation 5]
FIG. 10 illustrates a fifth variation of this first embodiment of the present
invention. It is also possible to use a cover 39E such as illustrated in FIG. 10 as the
cover that covers the inside end sections in the axial direction of the outer ring member
34 and hub 35. This cover 39E is such that part of the small-diameter cylindrical
section 66 is cut with one cutting-plane line 72E along the circumferential direction at a
location separated from the disk section 65 (position opposite in the axial direction from
the disk section 65), and by raising that portion toward the outside in the radial
direction, a cut and raised section 71E having linear cross section is formed in the
small-diameter cylindrical section 66 such that it extends diagonally downward toward
the outside in the axial direction from the small-diameter cylindrical section 66.
Therefore, the inside in the axial direction (right side in FIG. 10) of the cut and raised
section 71E is continuous with the small-diameter cylindrical section 66, and the
outside in the axial direction (left side in FIG. 10) is detached from the small-diameter
cylindrical section 66, and a water drainage hole 73 is formed in the detached portion.
[0072] With this variation, the water drainage hole 73 is open toward the outside in
the axial direction, and this opening section is surrounded by the cut and raised section
71E, the large-diameter cylindrical section 67 and the stepped section 69 such that it is
not exposed to the outside, so it is possible to further prevent foreign matter such as
water from entering inside the cover 39E.
[0073]
[Embodiment 2]
Next, a second embodiment of a hub unit bearing of the present invention will
be explained with reference to FIG. 11 to FIG. 13. The same reference numbers are
given to parts that are the same or equivalent to parts in the first embodiment, and
explanations of those parts will be omitted or simplified.

[0074] As illustrated in FIG. 11, the hub unit bearing 33Aof this embodiment is a hub
unit bearing for a follower wheel, and comprises an outer ring member 34A, a hub 35A
as an inner ring member, a plurality of balls 36A as rolling elements, seals 37A, 37B and
a cover 75.
[0075] The cover 75 has a disk section 76, and a cylindrical section 77 that is formed
by bending outward in the axial direction from the outer perimeter edge of disk section
76. A flange section 78 that protrudes outward in the radial direction is formed around
the outer circumferential surface in the middle section in the axial direction of the
cylindrical section 77, and with the outside surface of this flange section 78 brought into
contact with the surface 70A on the inside end of the outer ring member 34A, the cover
75 is fitted inside the inner circumferential surface 79 of the outer ring member 34A.
[0076] Moreover, as illustrated in FIG. 11, FIG. 12A and FIG. 12B, a groove section 80
having a semicircular cross section and recessed toward the inside in the radial
direction is formed in the tip end side (outside in the axial direction, and the left side in
FIG. 11) of the cylindrical section 77 of the cover 75. This groove section 80 is parallel
with the axis line, and is formed at a position in the axial direction that goes beyond the
flange section 78 a little. Therefore, as illustrated in FIG. 12A, the flange section 78 is
curved inward in the axial direction (toward the side of the disk section 76) in the
portion of the groove section 80.
[0077] By fitting the cover 75 inside the inner circumferential surface 79 of the outer
ring member 34A, a tunnel-shaped water drainage hole 81 having an Lrshaped cross
section (cross section with respect to a virtual plate that includes the center axis of the
cover 75) is formed between the groove section 80 and the inner circumferential surface
79 and the surface 70A on the inside end of the outer ring member 34A. In the case of
this embodiment, the flange section 78 is formed on the cylindrical section 77 of the
cover 75, so even when the groove section 80 that will become the fitting section is
formed in the cylindrical section 77, it is possible to keep the rigidity of the cylindrical
section 77 from decreasing. Therefore, it is possible to firmly fit the cover 75 inside the
outer ring member 34A.
[0078] Moreover, in the case of this embodiment, the width (P) in the circumferential
direction of the water drainage hole 81 (groove section 80) is preferably 4 times to 10
times the thickness (t) of the raw plate material. This is because, when the width (P)
in the circumferential direction is less than 4 times the plate thickness, processing the
groove section 80 becomes difficult, and there is a possibility that, due to interfacial
tension of water, sufficient drainage will not be obtained. When the width (P) exceeds

10 times the thickness (t), there is a possibility that the strength of the cylindrical
section will not be sufficient.
[0079] The cross-sectional shape of the groove section 80 illustrated in the figure is
semicircular, however, the cross-sectional shape is arbitrary. However, in
consideration of achieving both good drainage and ease of processing, it is preferred that
the height of the portion through which water passes be 0.5 mm or greater and be equal
to or less than the plate thickness (t). Furthermore, the location of the groove section is
the same as in the case of the first embodiment. In FIGS. 12A and 12B, in order to
more easily understand the construction of the groove section 80, the height of the
portion where water passes is represented as being greater than the plate thickness (t).
[0080] In the case of the cover 75 of this embodiment, it is not necessary to cut the
cylindrical section 77 in order to form the water drainage hole 81, so the possibility of
affecting the strength of the cylindrical section 77 is small. Therefore, after the cover
75 has been plastically worked (pressed) into a circular ring shape with a bottom and all
of the surfaces have been coated, it is possible to form and process the groove section 80.
It is also possible to use material easily rusts as the cover. Furthermore, the shape of
the cover 75 is comparatively simple, and there is no problem with the coating adhering
as in the case of a complex shape, so after the groove 80 has been formed, coating can be
performed easily.
[0081] Moreover, in the case of a hub unit bearing 33A that does not have an encoder
as in this embodiment, the cover 75 can be formed using inexpensive material such as
SPCC steel plate, and by coating the cover 75 it is possible to maintain the water
drainage performance and obtain a cover 75 that is rust proof. Preferably an
electrodeposition coating or baking coating is used as the coating. Also, instead of a
coating, it is possible to perform a plating process such as electroless nickel plating,
chrome plating, galvanization, tin plating or the like, or a combination of these.
[0082] As was explained above, in the case of the hub unit bearing 33Aof this
embodiment, a tunnel shaped water drainage hole 81 is formed between a groove section
80 that is formed in the cylindrical section 77 of the cover 75 such that it is recessed
toward the inside in the radial direction and the outer ring member 34A. Therefore,
the water drainage hole 81 can be formed in the cylindrical section 77 without cutting.
As a result, it is possible to maintain the strength of the cylindrical section 77 and
maintain a strong fit of the cover 75 with the outer ring member 34A.
[0083] When the cover 75 is viewed from underneath the vehicle (underneath in the
radial direction), the inside of the cover 75 is not exposed through the water drainage

hole 81 (the inside is covered by the portion of the groove section 80 and the outer ring
member 34, so it is possible to effectively prevent foreign matter such as water from
entering inside the cover 75.
[0084] Furthermore, there are no cuts in the cover 75, so rust proofing such as coating
the cover 75 can be performed easily, and thus it possible to improve the antirust
capability of the cover 75.
[0085] The other construction and function are the same as in the first embodiment
described above.
[0086]
[Embodiment 2, Variation]
FIG. 13 illustrates a variation of the second embodiment. It is also possible to
uses a cover 75A as illustrated in FIG. 13 as the cover that covers the inside end sections
in the axial direction of the outer ring member 34A and the hub 35A (see FIG. 11). In
this cover 75A, a groove section 80A is formed in the cylindrical section 77 such that it is
inclined at a specified angle (a) with respect to the axis line of the cover 75A.
[0087] When the groove section 80A is inclined with respect to the axis line of the
cover 75A in this way, by inclining the groove section 80A in the same direction as the
direction of rotation of the hub unit bearing 33A, it is possible to easily drain water by
the slinger 59 of the seal 37B and the rotation of the encoder 60 that is fastened to the
slinger 59, and thus it is possible to improve the water draining capability.
[0088]
[Embodiment 3]
Next, a third embodiment of the hub unit bearing of the present invention will
be explained with reference to FIG. 14. The same reference numbers will be used for
parts that are the same or equivalent to those in the first embodiment, and an
explanation of those parts will be omitted or simplified.
[0089] In the hub unit bearing 33B of this embodiment, a cover 82 as illustrated in
FIG. 14 is used. This cover 82 has a large-diameter cylindrical section 83 that fits
around the outer circumferential surface 68 of the outer ring member 34, a side wall
section 84 that extends from the inside end section in the axial direction of the
large-diameter cylindrical section 83 and comes in contact with the surface on the inside
end of the outer ring member 34, a small-diameter cylindrical section 85 that extends
toward the inside in the axial direction from the inner edge section of the side wall
section 84, a disk section 86 that extends toward the inside in the radial direction from
the inside end section in the axial direction of the small-diameter cylindrical section 85,

and an inner-diameter cylindrical section 87 that extends toward the outside in the
axial direction from the inner edge section of the disk section 86. In this cover 82 there
is a cut and raised section 71 that is formed in the small-diameter cylindrical section 85
such that it is raised toward the inside in the radial direction.
[0090] In this embodiment, a seal 89 is provided between the small-diameter outer
circumferential surface 88 that is formed around the inside end section in the axial
direction of the inner ring 45 and the inner circumferential surface of the
inner-diameter cylindrical section 87 of the cover 82. This seal 89 comprises a metal
core 90 having an L-shaped cross section that is pressure fitted around the
small-diameter outer circumferential surface 88 of the inner ring 45, and an elastic seal
section 92 that is attached to the metal core 90 and has a seal lip 91 that comes in
sliding contact with the inner circumferential surface of the inner-diameter cylindrical
section 87. This seal 89 prevents various kinds of foreign matter from entering inside
the cover 82. The seal lips91 is not limited to contact type that come in contact with
the inner-diameter cylindrical section 87 as described above, and a non-contact type
that forms a small space (labyrinth seal) between the seal lip and the inner-diameter
cylindrical section 87 could be used.
[0091] In the case of this embodiment having the construction described above, the
seal 89 that is provided between the cover 82 and the inner ring 45 can effectively
prevent foreign matter such as moisture, fine particles and the like from entering inside
the cover 82 through the space between the cover 82 and the inner ring 45.
[0092] The other construction and function are the same as in the first embodiment
described above.
[0093]
[Embodiment 4]
Next, a fourth embodiment of a hub unit bearing of the present invention will
be explained with reference to FIG. 15 to FIG. 20. Features of the hub unit bearing
33C of this embodiment are the construction of the cover 93 that covers the sensing
space 22 in the detecting section between the encoder 60 and the sensor 61 from the
inside in the axial direction, and the construction of the water drainage hole 94 that is
formed in the cover 93. The same reference numbers are given to parts that are the
same or equivalent to those of the first embodiment, and explanations of those parts are
omitted or simplified.
[0094] The cover 93 that is used in this embodiment is made of metal such as
non-magnetic stainless steel and comprises a large-diameter cylindrical section 95, a

side wall section 96, a small-diameter cylindrical section 97, a disk section 98 and an
inner-diameter cylindrical section 99. The large-diameter cylindrical section 95 is
fitted onto the inside end section in the axial direction of the outer ring member 34.
The side wall section 96 is formed by bending at a right angle toward the inside in the
radial direction from the inside end section in the axial direction of the large-diameter
cylindrical section 95, and except for part in the circumferential direction (the portion
located on the top end when in operation), the outside surface in the axial direction of
the side wall section 96 comes in contact with the surface 70 on the inside end in the
axial direction of the outer ring member 34. The small-diameter cylindrical section 97
is formed by bending at a right angle toward the inside in the axial direction from the
inside end section in the radial direction of the side wall section 96. The disk section 98
is formed by bending at a right angle toward the inside in the radial direction from the
inside end section in the axial direction of the small-diameter cylindrical section 97.
Furthermore, the inner-diameter cylindrical section 99 is formed by bending at a right
angle toward the outside in the axial direction from the inside end section in the radial
direction of the disk section 98, and is located on the inside in the radial direction of the
small-diameter cylindrical section 97. Moreover, the edge on the tip end (edge on the
outside end in the axial direction) of this inner-diameter cylindrical section 99 is located
further toward the outside in the axial direction than the inside surface in the axial
direction of the side wall section 96, and this edge on the tip end closely faces the edge
section on the inner perimeter of the inside surface in the axial direction of the encoder
60, forming a labyrinth seal in that portion. The work of fastening the cover 93 having
this kind of construction to the inside end section in the axial direction of the outer ring
member 34 is performed by using a jig, the pressure thereof being made of synthetic
resin for example, to press the inside surface in the axial direction of the side wall
section 96 of the cover 93. In the case of this embodiment, a rust proofing process such
as cation electrodeposition coating is performed on the cover 93.
[0095] Moreover, the material of the cover 93 can be suitably selected within a range
that accomplishes the original objective of covering the inside end section in the axial
direction of the outer ring member 34 and hub 35, however, from the aspect of
preventing leakage of magnetic flux coming from and entering the inside surface in the
axial direction of the encoder 60, which is the detected surface, preferably a
non-magnetic material such as non-magnetic stainless steel, aluminum alloy, synthetic
resin and the like is used.
[0096] Moreover, in this embodiment, there is no bulging section 32 (see FIG. 26 to

FIG. 31) formed in the cover 93, and there is a water drainage hole 94 formed in the
portion located at the bottom end of the cover 93 in the operating state between the
small-diameter cylindrical section 97 and the side wall section 96, and has a size
capable of draining foreign matter. Particularly in the case of this embodiment, of this
water drainage hole 94, the bottom end section (bottom edge) 101 of the portion that is
opened in the side wall section 96 is located in the middle section in the radial direction
of the side wall section 96, and is such that it does not reach the outer perimeter edge
section of the side wall section 96 (does not pass through in the radial direction). With
this kind of construction, a covering section 102 that is formed from the remaining
section of the side wall section 96 is provided further on the outside (bottom side during
operation) in the radial direction of this side wall section 96 than the opening portion of
the water drainage hole 94. Furthermore, in this embodiment, of the water drainage
hole 94, the bottom end section 101 that is opened in the side wall section 96 is located
further downward than the bottom end section 103 of the inner circumferential surface
on the inside end in the axial direction of the outer ring member 34. Moreover in this
embodiment, the bottom end section 101 of the water drainage hole 94 is inclined in a
direction toward the outside (downward during operation) in the radial direction going
away from the surface 70 on the inside end in the axial direction of the outer ring
member 34. The shape and size of the water drainage hole 94 is not limited to that
illustrated in the drawings and can be appropriately changed within range that allows
drainage of foreign matter that has entered inside. Furthermore, the hub unit bearing
of the present invention can be changed according to the type of wheel used, the
application or according to the region the same way as in the first embodiment described
above.
[0097] Moreover, in the case of this embodiment, a small-diameter stepped section 104
is formed in the inside end section in the axial direction of the inner ring 45A whici
forms the hub 35 with the main hub 44. As means for sealing, a seal ring 105 is fitted
onto this small-diameter stepped section so as to come in contact with the stepped
surface 106 that exists on the outside end section in the axial direction of this
small-diameter stepped section 104. The seal ring 105 comprises an L-shaped metal
core 107 and a seal member 108 made of an elastic material that is attached and
fastened to the outer surface of the metal core 107. The seal member 108 comprises
one or a plurality of seal lips 109 (there is one in the example in the figure), and the edge
on the tip end of this seal lip 109 comes in sliding contact all the way around a seal
surface 110, which is the inner circumferential surface of the inner-diameter cylindrical

section 99 of the cover 93. The work of fitting and fastening the seal ring 105, having
this kind of construction around the outside of the small-diameter stepped section 104 of
the inner ring 45A can be performed after fastening the cover 93 to the inside end
section in the axial direction of the outer ring member 34. The drawings illustrate the
shape of the edge on the tip end of the seal lip 109 in the free state. In this embodiment,
this kind of seal ring 105 is used to close off the sensing space 22 where the encoder 60
and detecting section of the sensor 61 are located from the outside space.
[0098] Moreover, a combined seal ring 112 is provided between a shoulder section 111,
which exists in the portion between the inner raceway 51b on the inside in the axial
direction that is formed around the inner ring 45A and the small-diameter stepped
section 104, and the inner circumferential surface of the inside end section in the axial
direction of the outer ring member 34. A permanent magnet type encoder 60 is
attached and fastened to the inside surface in the axial direction of a slinger 113 of this
combined seal ring 112, with the characteristics of the inside surface in the axial
direction of this encoder 60, which is the detected surface, alternately changing at
uniform intervals in the circumferential direction.
[0099] In this embodiment, an active sensor 61, having a magnetic detecting element
such as a Hall element or magnetic resistance element in the detecting section, is
supported by and fastened to the cover 93 having the construction described above. In
this embodiment, the sensor 61 is fitted inside a support section 114 that is formed by
causing the portion of the side wall section 96 of the cover 93 that is located on the top
end during operation to bulge inward in the axial direction. The detection section of
this sensor 61 faces the detected surface of the encoder 60, which is the inside surface in
the axial direction. The method for fastening the sensor 61 in the cover 93 is not
particularly specified, however, various fastening methods can be employed such as a
molded formation, pressure fitting, adhesive fastening using an adhesive, set screw
fastening or the like. In the example illustrated in the drawings, the base end section
of a harness 115 is connected to the sensor 61, and this harness is drawn out in the
diameter direction such that electric power can be supplied to the sensor 61 and
detection signals from the sensor 61 can be retrieved. Moreover, a connector 116 for
connecting another harness or control device is provided on the tip end section of this
harness 115. However, it is also possible to omit this kind of harness 115 and to fasten
the connector 116 directly to the sensor 61, or it is also possible to draw this harness 115
inward in the axial direction.
[0100] With the hub unit bearing 33C of this embodiment that is constructed as

described above, it is possible to suppress foreign matter such as muddy water from
entering inside the sensing space 22 where the encoder 60 and the detecting section of
the sensor 61 are located through the water drainage hole 94 that is formed in the cover
93, and it is also possible to efficiently drain any foreign matter to the outside space.
[0101] In other words, in the case of this embodiment, a water drainage hole 94 is
formed in the portion located at the bottom of the cover 93 during operation that is
between the small-diameter cylindrical section 97 and the side wall section 96, and the
bottom end section (bottom edge) 101 of the portion that is opened in the side wall
section 96 is located in the middle section in the radial direction of the side wall section
96. Therefore, there is a cover section 102 that is formed by the remaining portion of
the side wall section 96 that is further on the outside (bottom side during operation) in
the radial direction that the opening section of the water drainage hole 94. As is
clearly illustrated in FIG. 19, even when viewing the cover 93 from below the vehicle,
the portion of the water drainage hole 94 that is opened in the side wall section 96 is
covered by the cover section 102 and is not exposed. Moreover, when the cover 93 is
viewed from the inside in the axial direction, the portion that is opened in the side wall
section 96 is covered by the surface 70 on the inside end in the axial direction of the
outer ring member 34. Therefore, in this embodiment, it becomes difficult for foreign
matter such as muddy water that is splashed during operation of the vehicle to enter
inside the sensing space 22 through the portion that is opened in the side wall section
96.
[0102] Furthermore, the inner-diameter cylindrical section 99 of the cover 93 is
located on the inside in the radial direction of the portion of the water drainage hole 94
that is opened in the small-diameter cylindrical section 97 of the cover 93. Therefore,
foreign matter that enters from the portion opened in the small-diameter cylindrical
section 97 is thrown by the outer circumferential surface of the inner-diameter
cylindrical section 99, or drops down after adhering to the outer circumferential surface
of the inner-diameter cylindrical section 99, and is discharged to the outside space.
Particularly, the edge on the tip end of the inner-diameter cylindrical section 99 is
located further outward in the axial direction than the inside surface in the axial
direction of the side wall section 96, so it is possible to sufficiently prevent foreign
matter from entering from the portion of the water drainage hole 94 that is opened in
the small-diameter cylindrical section 97.
[0103] In this way, in this embodiment, it is possible to suppress foreign matter from
entering inside the cover 93 through the water drainage hole 94.

[0104] Furthermore, in this embodiment, the bottom end section 101 of the portion of
the water drainage hole 94 that is opened in the side wall section 96 is located further
downward than the bottom end section 103 of the inner circumferential surface of the
inside end section in the axial direction of the outer ring member 34. Therefore, it is
possible to effectively prevent foreign matter from accumulating between the inner
circumferential surface of the inside end in the axial direction of the outer ring member
34 and the outside surface in the axial direction of the side wall section 96, and by
taking advantage of the force of gravity, it is possible to efficiently drain foreign matter
to the outside space. Moreover, the bottom end section 101 is inclined downward going
away from the surface 70 on the inside end in the axial direction of the outer ring
member 34, so it is possible to further improve the ability to drain foreign matter to the
outside space. In this embodiment, it is not necessary to form a bulging section 32 for
forming a water drainage hole in the cover 93 as in the construction of the prior
invention described above (see FIGS. 26 to 31), so together with being able to prevent a
reduction in freedom of selecting materials for the cover, it is possible to prevent an
increase in processing cost. The cover 93 can also be fastened to the outer ring member
34 with sufficient strength. In this embodiment, a labyrinth space is formed between
the edge on the tip end of the inner-diameter cylindrical section 99 and the inner
perimeter edge of the inside surface in the axial direction of the encoder 60, so it is
possible to prevent foreign matter from entering through the water drainage hole 94
and reaching the seal ring 105. Therefore, it is possible to prevent early wear of the
edge on the tip end of the seal lip 109 of the seal ring 105. By manufacturing the cover
93 using a non-magnetic material such as non-magnetic stainless steel, and by causing
the edge on the tip end of the inner-diameter cylindrical section 99 to closely face the
inside surface in the axial direction of the encoder 60, it is possible to maintain the
amount of magnetic flux from the encoder 60 reaching the magnetic detecting element of
the sensor 61 without magnetic flux leaking to the cover 93. In so doing, it is possible
to sufficiently maintain reliability of the rotational speed measurement by the sensor
61.
[0105] The other construction and function are the same as those of the first
embodiment described above.
[0106]
[Embodiment 4, Variation l]
FIG. 21 illustrates a first variation of the fourth embodiment of the present

invention. In this variation, a triangular shaped side wall sections 117 are formed on
both sides in the circumferential direction of the water drainage hole 94Athat is formed
in the portion of the cover 93A between the small-diameter cylindrical section 97Aand
the side wall section 96A. These side wall sections 117 can be formed by pressing at
the same time that the water drainage hole 94A is formed. In this variation, with this
kind of construction, it is possible to adjust the flow of air, and thus it is possible to
improve the effect of preventing water drops from entering inside the sensing space 22
(FIGS. 1 and 2).
[0107]
[Embodiment 4, Variation 2]
FIG. 22 and FIG. 23 illustrate a second variation of the fourth embodiment of
the present invention. In this embodiment, the seal ring 105A as the seal is fitted onto
the middle section in the axial direction of the small-diameter stepped section 104A
without coming into contact with the step surface 106 that is formed on the outside end
section in the axial direction of this small-diameter stepped section 104A. In the case
of this embodiment having this kind of construction, the profile irregularity of the
portion near the outside end in the axial direction of the step surface 106 and the
small-diameter stepped section 104A does not adversely affect the installation precision
of the seal ring 105A, so it is not necessary to perform a finishing process (grinding
process) on these surfaces. On the other hand, when performing a polishing process
using a formed grindstone on the outer surface of the inner ring 45B, the interference
between the formed grindstone and the inner ring 45B becomes a problem.
Particularly, when grinding both of the shoulder section 111 and the middle section and
inside end section in the axial direction of the small-diameter stepped section 104Aof
the outer circumferential surface of the inner ring 45B at the same time, this problem of
interference occurs easily. Therefore, in this embodiment, a relief concave groove 118 is
formed all the way around the outside end in the axial direction of the small-diameter
stepped section 104Ain the portion that is separated outward in the axial direction from
the portion where the seal ring 105A fits, and this relief groove 118 sufficiently
maintains the amount of caving inward in the radial direction. As a result, in this
embodiment, a formed grindstone 119 comprising a diamond wheel such as illustrated
in FIG. 23 is used to perform simultaneous grinding of the inner raceway 51b, the
shoulder section 111 and the middle section and inside end section in the axial direction
of the small-diameter stepped section 104A of the outer circumferential surface of the
inner ring 45B at the same time without there being interference between the

grindstone 119 and the inner ring 45B.
[0108] Moreover, in this embodiment, a seal member 108A comprising two seal lips
109Aand 109B are attached and fastened to the outer circumferential surface of the
metal core 107 of the seal ring 105A. Both of these seal lips 109A, 109B extend in a
direction going away from each other in the axial direction, and the edges on the tip
ends come in sliding contact all around the seal surface 110A, which is the inner
circumferential surface of the inner-diameter cylindrical section 99Aof the cover 93B.
Moreover, grease is held between both of these seal lips 109A, 109B.
[0109] In this embodiment as well, the cover 93B is made of metal such as
non-magnetic stainless steel. The inner-diameter cylindrical section 99Aof the cover
93B is a partial cylindrical cone shape that is inclined in a direction such that the outer
diameter dimension becomes larger going inward in the axial direction. Furthermore,
the edge on the tip end (outside edge in the axial direction) of the inner-diameter
cylindrical section 99A is located further outward in the axial direction than the surface
on the inside end in the axial direction of the side wall section 96 of the cover 93B, and
this edge on tip end closely faces the outer perimeter edge section of the step surface 106
that is formed around the inner ring 45B, forming a labyrinth seal in that portion.
[0110] In the case of this embodiment having construction as described above, two seal
lips 109A, 109B are provided on the seal ring 105, so when compared with the case of
providing only one seal lip, it is possible to further improve the effect of preventing
foreign matter such as muddy water from entering inside. Also, there is grease held
between both of these seal lips 109A, 109B, so together with being able to prevent an
increase in rotation torque of the hub 35 caused by these two seal lips 109A, 109B, it is
possible to prevent wear of the edges on the tip ends of the seal lips 109A, 109B.
[0111] Moreover, the edge on the tip end of the inner-diameter cylindrical section 99A
of the cover 93B is located further outward in the axial direction than the inside surface
in the axial direction of the side wall section 96, so it is possible to sufficiently obtain the
effect of preventing foreign matter from entering from the portion that is opened in the
small-diameter cylindrical section 97 of the water drainage hole 94 that is formed in the
bottom end section of the cover 93B. Furthermore, the small-diameter cylindrical
section 99A is a partial conical cylinder that is inclined such that the outer diameter
dimension becomes larger going inward in the axial direction, so it is possible to
efficiently drain foreign matter that has entered inside the sensing space 22 through the
water drainage hole 94 to the outside space through the water drainage hole 94. In
other words, after foreign matter that has entered through the water drainage hole 94

has adhered to the outer circumferential surface of the inner-diameter cylindrical
section 99A, that foreign matter is led along that outer circumferential surface to the
outside surface in the axial direction of the disk section 98, and by the force of gravity
acting on it, reaches the inner circumferential surface of the small-diameter cylindrical
section 97. Therefore, it is possible to efficiently drain foreign matter that has entered
into sensing space 22 through the portion that is opened in the small-diameter
cylindrical section 97 of the water drainage hole 94. In the case of this variation as
well, the bottom end section 101 of the water drainage hole 94 is an inclined surface that
is inclined downward going away from the surface 70 on the inside end in the axial
direction of the outer ring member 34, so it is possible to even further improve the
capability to drain foreign matter to the outside space.
[0112] Moreover, in this variation, by making the inner-diameter cylindrical section
99A be a partial conical cylinder, and because the seal surface 110A, which is the inner
circumferential surface of the inner-diameter cylindrical section 99A, is tapered, it is
possible to effectively prevent the seal ring 105A, which extends outward in the axial
direction, from being turned up even when the seal ring 105Ais fitted onto the
small-diameter stepped section 104B.
[0113] Furthermore, in this embodiment, a labyrinth seal is formed between the edge
on the tip end of the inner-diameter cylindrical section 99A and the outer perimeter
edge of the step surface 106, so it is possible to prevent foreign matter that has entered
through the water drainage hole 94 from reaching the seal ring 105A. Therefore, it is
possible to prevent early wear of the edges on the tip ends of the seal lips 109A, 109B.
Moreover, by manufacturing the cover 93B using a non-magnetic material such as
non-magnetic stainless steel, and by causing the edge of the tip end of the
inner-diameter cylindrical section 99A to closely face the outer perimeter portion of the
step surface 106, it is possible to maintain the amount of magnetic flux from the encoder
30 that reaches the magnetic detection element of the sensor without that magnetic flux
leaking to the cover 93B. Therefore, it is possible to sufficiently maintain the
reliability of the rotational speed measurement of the sensor.
[Explanation of Reference Numbers]
1, la, lb Hub unit bearing
2 Outer ring member
3 Inner ring member (hub)
4 Rolling elements (balls)

5 Rotational speed detector
6 Outer raceway
7 Stationary-side flange
8 Main hub
9 Inner ring
10 Inner raceway
11 Rotating-side flange
12 Outer ring for a constant velocity joint
13 Spline hole
14 Seal ring
15 Rolling element installation space
16 Combined seal ring
17, 17a, 17b Cover

18 Seal member
19 Encoder
20 Sensor
21 Slinger
22 Sensing space
23, 23a Water drainage hole
24 Large-diameter cylindrical section
25 Disk section
26 Small-diameter cylindrical section
27 Large-diameter cylindrical section
28 Side wall section
29 Small-diameter cylindrical section
30 Disk section
31 Inner-diameter cylindrical section
32 Bulge section

33, 33a, 33b, 33c Hub unit bearing
34, 34a Outer ring member
35, 35a Inner ring member (hub)
36, 36a Rolling elements (balls)
37a, 37A, 27b, 37B Seal
38 Rotational speed detector
39, 39A, 39B, 39C, 39D Cover

40 Knuckle
41 Retaining hole
42 Stationary-side flange
43 Bolt
44 Main hub
45, 45A, 45B Inner ring
46 Rotating-side flange
47 Hub bolt
48 Spline hole
49 Small-diameter stepped section
50a, 50b Outer raceway
51a, 51b Inner raceway
52 Retainer
53 Rolling element installation space
54 Inner circumferential surface
55 Metal core
56 Elastic seal section
57 Outer circumferential surface
58 Seal lip
59 Slinger
60 Encoder
61 Sensor
62 Detecting section
63 Detected surface
64 Through hole
65 Disk section
66 Small-diameter cylindrical section
67 Large-diameter cylindrical section
68 Outer circumferential surface
69 Stepped section
70 Inside end surface

71, 71C, 71D, 71E Cut and raised section
72, 72C, 72D, 72E Cutting plane line

73 Water drainage hole
74 Sensor hole

75, 75A Cover
76 Disk section
77 Cylindrical section
78 Flange section
79 Inner circumferential surface
80 Groove section
81 Water drainage hole
82 Cover
83 Large-diameter cylindrical section
84 Stepped section
85 Small-diameter cylindrical section
86 Disk section
87 Inner-diameter cylindrical section
88 Small-diameter outer circumferential section
89 Seal
90 Metal core
91 Seal lips
92 Elastic seal section

93, 93A, 93B Cover
94, 94A Water drainage hole

95 Large-diameter cylindrical section
96 Side wall section
97 Small-diameter cylindrical section
98 Disk section
99, 99A Inner-diameter cylindrical section
101 Bottom end section
102 Covering section
103 Bottom end section

104, 104A Small-diameter stepped section
105, 105A Seal ring

106 Step surface
107 Metal core

108, 108A Seal member
109, 109A, 109B Seal lips
110, 110A Seal surface

111 Shoulder section
112 Combined seal ring
113 Slinger
114 Retainer
115 Harness
116 Connector
117 Side wall section
118 Relief concave groove
119 Formed grinding stone
120 Grease

CLAIMS
What is claimed is
1. A hub unit bearing comprising:
an outer ring member, which is a stationary ring;
an inner ring member, which is a rotating ring that can rotate relative to the
outer ring member via a plurality of rolling elements; and
a cover that covers the inside end sections in the axial direction of the outer
ring member and inner ring member,
the cover having:
a disk section; and
a cylindrical section that is bent outward in the axial direction from the outer
perimeter edge section of the disk section, and is fitted with and fastened to the outer
ring member, and
the cylindrical section having a cut and raised section that is formed in part in
the circumferential direction of the cylindrical section by being cut and raised toward
the inside or outside in the radial direction of the cylindrical section, such that this cut
and raised section forms a water drainage hole that passes through from the inside to
the outside of the cover.
2. The hub unit bearing according to claim 1, wherein
the cut and raised section is cut and raised by cutting two cutting-plane lines
along the circumferential direction of the cylindrical section, and water drainage holes
are formed on both sides in the axial direction of the cut and raised section.
3. The hub unit bearing according to claim 1, wherein the cut and raised section is
cut and raised by cutting one cutting-plane line along the circumferential direction of
the cylindrical section such that one side in the axial direction of the cut and raised
section is continuous with the cylindrical section, and the water drainage hole is formed
on the other side in the axial direction.
4. The hub unit bearing according to claim 3, wherein
the cut and raised section has an L-shaped cross section in the cross section in
the axial direction of the cover.
5. The hub unit bearing according to claim 3, wherein

the cut and raised section has a linear shaped cross section in the cross section
in the axial direction of the cover.
6. A hub unit bearing comprising;
an outer ring member, which is a stationary ring;
an inner ring member, which is a rotating ring that can rotate relative to the
outer ring member via a plurality of rolling elements; and
a cover that covers the inside end sections in the axial direction of the outer
ring member and inner ring member,
the cover having:
a disk section; and
a cylindrical section that is bent outward in the axial direction from the
perimeter edge section of the disk section, and is fitted with and fastened to the outer
ring member, and
the cylindrical section having a groove section that is recessed toward the
inside or the outside in the radial direction along the axial direction, and a water
drainage hole that passes through from the inside to the outside of the cover is formed in
the portion between the groove section and the outer ring member.
7. The hub unit bearing according to claim 6, wherein
the groove section is formed in the cylindrical section such that the groove
section is parallel with the axial direction of the cover.
8. The hub unit bearing according to claim 6, wherein
the groove section is formed in the cylindrical section such that the groove
section is inclined with respect to the axial direction of the cover.
9. A hub unit bearing comprising:
an outer ring member, which is a stationary ring;
an inner ring member, which is a rotating ring that can rotate relative to the
outer ring member via a plurality of rolling elements; and
a cover that covers the inside end sections in the axial direction of the outer
ring member and inner ring member,
the cover having:
a disk section; and

a cylindrical section that is bent outward in the axial direction from the
perimeter edge section of the disk section, and is fitted with and fastened to the outer
ring member, and
the cylindrical section having at least: a large-diameter cylindrical section that
is fitted onto and fastened to the inside end section in the axial direction of the outer
ring member; a side wall section that is bent inward in the radial direction from the
inside end section in the axial direction of the large-diameter cylindrical section, with
the outside surface in the axial direction thereof coming in contact with the surface on
the inside end in the axial direction of the outer ring member; and a small-diameter
cylindrical section that is continuous with the disk section and is bent inward in the
axial direction from the inside end section in the radial direction of the side wall section,
and
a water drainage hole is formed in a portion in part in the circumferential
direction of the cylindrical section that connects the small-diameter cylindrical section
and the side wall section, and the bottom end section of the water drainage hole located
in the middle section in the radial direction of the side wall section is located further
downward then the bottom end section of the inner circumferential surface of the inside
end section in the axial direction of the outer ring member.
10. The hub unit bearing according to any one of the claims 1, 6 and 9 further
comprising
a seal member made of an elastic material and that is provided on the inside
end section in the radial direction of the disk section, the edge on the tip end of a seal lip
of the seal member coming in contact all the way around the surface of the inner ring
member or a separate member that rotates together with the inner ring member.
11. The hub unit bearing according to any one of the claims 1, 6 and 9, further
comprising:
an inner-diameter cylindrical section that is bent outward in the axial direction
from the inside end section in the radial direction of the disk section, the inner
circumferential surface of the inner-diameter cylindrical section functioning as a seal
surface with which the edge on the tip end of the seal member made of elastic material,
which is a seal that is provided between the cover and the inner ring member or
separate member that rotates together with the inner ring member, comes in sliding
contact with or closely faces all around in the circumferential direction.

12. The hub unit bearing according to any one of the claims 1, 6 and 9, wherein
the water drainage hole, during operation, is located within a range of ±35° in
the circumferential direction with an intersection point where a plumb line that passes
through the center axis of the cover crosses the bottom end section of the cover.
13. The hub unit bearing according to any one of the claims 1, 6 and 9, wherein
an encoder is provided on the outer circumferential surface of the inside end
section in the axial direction of the inner ring member, and a sensor having a detecting
unit that faces the encoder is provided in the cylindrical section or part of the disk
section of the cover.



(S4) Title: HUB UNIT BEARING.
(54) &WO>&lft : /\?ii»/Hift

Abstract:

Provided is a hub unit bearing wliich permits securing of
the lining strength of a cover (39) with respect lo an outer race member
(34) und which has a structure that is not susceptible to intrusion of for-
eign matter to the inside through a drain hole (73) that iff provided to the
cover (39), The cover (39). which is used to cover the axially inner end of
a hub unit bearing (33), comprises a disk section (65), a small diameter
nibular section (66) and a large diameter tubular section (67) mat are
formed bending from the outer circumferential section of this disk section
(65) toward the axinl direction. Particularly, in the small diameter tubular
section (66). there is formed an cut-and-bent portion (71) which is crculed
by cutting und bending u portion of the small diameter tubular section
(66) In the radially inward direction, A drain hole (73) which allows the
inside and outside of the cover (39) to communicute with each odier is
provided to the portion which is separated by this cut-and-bent portion
(71) from the small diameter tubular section (66).