U.S. patent application number 14/467309 was filed with the patent office on 2015-03-05 for rotating device.
This patent application is currently assigned to SAMSUNG ELECTRO-MECHANICS JAPAN ADVANCED TECH. CO. LTD.. The applicant listed for this patent is SAMSUNG ELECTRO-MECHANICS JAPAN ADVANCED TECH. CO. LTD.. Invention is credited to Satoshi HATAHARA, Ryusuke SUGIKI, Motoyuki SUGIURA, Shunsuke TAKAGAKI, Futoshi YOSHIMATSU.
Application Number | 20150062749 14/467309 |
Document ID | / |
Family ID | 52582901 |
Filed Date | 2015-03-05 |
United States Patent
Application |
20150062749 |
Kind Code |
A1 |
SUGIKI; Ryusuke ; et
al. |
March 5, 2015 |
ROTATING DEVICE
Abstract
A rotating device includes a retained assembly including a
spherical retained member with a spherical encircled face, and an
encircling member that includes an annular end face which encircles
the spherical retained member and which extends outwardly in a
radial direction, a retainer assembly including a retainer member
which includes an encircling face encircling the encircled face and
which retains thereinside a part of the spherical retained member,
and a facing member that faces the encircling member in an axial
direction, the retainer assembly supporting the retained assembly
in a freely and relatively rotatable manner, and forming a fluid
dynamic bearing mechanism, and a thrust dynamic pressure generating
groove formed in at least either one of a surface of the encircling
member and a surface of the facing member, which surfaces face with
each other in the axial direction.
Inventors: |
SUGIKI; Ryusuke; (Fujieda
City, JP) ; SUGIURA; Motoyuki; (Fujieda City, JP)
; YOSHIMATSU; Futoshi; (Fujieda City, JP) ;
HATAHARA; Satoshi; (Fujieda City, JP) ; TAKAGAKI;
Shunsuke; (Fujieda City, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRO-MECHANICS JAPAN ADVANCED TECH. CO. LTD. |
Fujieda City |
|
JP |
|
|
Assignee: |
SAMSUNG ELECTRO-MECHANICS JAPAN
ADVANCED TECH. CO. LTD.
Fujieda City
JP
|
Family ID: |
52582901 |
Appl. No.: |
14/467309 |
Filed: |
August 25, 2014 |
Current U.S.
Class: |
360/97.13 ;
415/110 |
Current CPC
Class: |
F04D 29/0513 20130101;
F04D 17/08 20130101; F04D 17/16 20130101; G11B 19/2036 20130101;
F04D 25/0653 20130101; F04D 29/057 20130101 |
Class at
Publication: |
360/97.13 ;
415/110 |
International
Class: |
G11B 33/14 20060101
G11B033/14; F04D 29/057 20060101 F04D029/057; F04D 17/08 20060101
F04D017/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2013 |
JP |
2013-177210 |
Oct 30, 2013 |
JP |
2013-225676 |
Claims
1. A rotating device comprising: a retained assembly including a
spherical retained member with a spherical encircled face, and a
first encircling member that includes an annular end face which
encircles the spherical retained member and which extends outwardly
in a radial direction; a retainer assembly including a retainer
member which includes an encircling face encircling the encircled
face and which retains thereinside a part of the spherical retained
member, and a facing member that faces the first encircling member
in an axial direction, the retainer assembly supporting the
retained assembly in a freely and relatively rotatable manner, and
forming a fluid dynamic bearing mechanism; and a first thrust
dynamic pressure generating groove formed in at least either one of
a surface of the first encircling member and a surface of the
facing member, which surfaces face with each other in the axial
direction.
2. The rotating device according to claim 1, wherein the spherical
retained member includes apart overlapping an area of the first
encircling member in the axial direction.
3. The rotating device according to claim 1, further comprising a
rotating body which is supported by the fluid dynamic bearing
mechanism and which includes amount portion on which a recording
disk is to be mounted, wherein the fluid dynamic bearing mechanism
positions a weight center of the rotating body when the recording
disk is mounted thereon at a substantial center of the spherical
retained member in the axial direction.
4. The rotating device according to claim 1, wherein the retainer
member includes a radial dynamic pressure generating groove.
5. The rotating device according to claim 4, wherein a radial
difference between an inscribed circle of an area where the first
thrust dynamic pressure generating groove is formed and a
circumscribed circle thereof is larger than a distance of an area
where the radial dynamic pressure generating groove is formed in
the axial direction.
6. The rotating device according to claim 1, wherein the encircling
face includes a tapered face contacting the encircled face when the
rotating device is not rotated.
7. The rotating device according to claim 1, wherein the encircling
face includes an annular portion with a center axis inclined
relative to a rotation axis of the fluid dynamic bearing
mechanism.
8. The rotating device according to claim 1, wherein the facing
member is formed integrally with the retainer member.
9. The rotating device according to claim 1, further comprising a
second encircling member which is supported by the retained
assembly in a fixed manner, wherein a second thrust dynamic
pressure generating groove is formed in at least either one of a
surface of the second encircling member and a surface of the facing
member, which surfaces face with each other in the axial
direction.
10. The rotating device according to claim 1, further comprising a
tapered seal located at a position overlapping an area of the
spherical retained member in the axial direction.
11. The rotating device according to claim 1, wherein the fluid
dynamic bearing mechanism has a dimension in the axial direction on
a line passing through a center of the spherical retained member
which is equal to or smaller than 4.1 mm.
12. The rotating device according to claim 1, further comprising a
rotating body which is supported by the fluid dynamic bearing
mechanism and which includes an engaged portion to be engaged with
a center hole of the recording disk, wherein the spherical retained
member includes a portion overlapping an area of the engaged
portion in the axial direction.
13. The rotating device according to claim 1, further comprising a
rotating body which is supported by the fluid dynamic bearing
mechanism and which includes an annular magnet, wherein the
spherical retained member includes a portion overlapping an area of
the magnet in the axial direction.
14. A rotating device comprising: a retained assembly including a
retained member in a truncated cone shape having a tapered
encircled face, and a first encircling member that includes an
annular end face which encircles the truncated conical retained
member and which extends outwardly in a radial direction; a
retainer assembly including a retainer member which includes an
encircling face encircling the encircled face and which retains
thereinside a part of the truncated conical retained member, and a
facing member that faces the first encircling member in an axial
direction, the retainer assembly supporting the retained assembly
in a freely and relatively rotatable manner, and forming a fluid
dynamic bearing mechanism; and a first thrust dynamic pressure
generating groove formed in at least either one of a surface of the
first encircling member and a surface of the facing member, which
surfaces face with each other in the axial direction.
15. The rotating device according to claim 14, wherein the retainer
member includes a radial dynamic pressure generating groove.
16. The rotating device according to claim 15, wherein a radial
difference between an inscribed circle of an area where the first
thrust dynamic pressure generating groove is formed and a
circumscribed circle thereof is larger than a distance of an area
where the radial dynamic pressure generating groove is formed in
the axial direction.
17. The rotating device according to claim 14, wherein the facing
member is formed integrally with the retainer member.
18. The rotating device according to claim 14, further comprising a
second encircling member which is supported by the retained
assembly in a fixed manner, wherein a second thrust dynamic
pressure generating groove is formed in at least either one of a
surface of the second encircling member and a surface of the facing
member, which surfaces face with each other in the axial
direction.
19. The rotating device according to claim 14, further comprising a
rotating body which is supported by the fluid dynamic bearing
mechanism and which includes an annular magnet, wherein the
truncated conical retained member includes a portion overlapping an
area of the magnet in the axial direction.
20. A rotating device comprising: a retained assembly including a
retained member that has a spherical or tapered encircled face, and
an encircling member that includes an annular end face which
encircles the retained member and which extends outwardly in a
radial direction; a retainer assembly including a retainer member
which includes an encircling face encircling the encircled face and
which retains thereinside a part of the retained member, and a
facing member that faces the encircling member in an axial
direction, the retainer assembly supporting the retained assembly
in a freely and relatively rotatable manner, and forming a fluid
dynamic bearing mechanism; a thrust dynamic pressure generating
groove formed in at least either one of a surface of the encircling
member and a surface of the facing member, which surfaces face with
each other in the axial direction; a rotating body which is
supported by the fluid dynamic bearing mechanism and which is fixed
with a vane that creates wind when rotated; and a drive mechanism
that rotates the rotating body.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present disclosure relates to a rotating device, such as
a disk drive device that rotates and drives recording disks, and a
fan motor that rotates to produce wind.
[0003] 2. Description of the Related Art
[0004] Disk drive devices like hard disk drives are becoming
compact and increasing the storage capacity, and are built in
various electric devices. In particular, disk drive devices are
nowadays built in portable electric devices, such as a laptop
computer, a tablet terminal, and a portable music player.
[0005] For example, JP 2011-103150 A discloses a disk drive device
that employs a fluid dynamic bearing mechanism as a bearing.
[0006] There is a demand of a further thinning for disk drive
devices including one disclosed in JP 2011-103150 A. When, however,
disk drive devices are made thin, an axial span of the radial
dynamic bearing part in the fluid dynamic bearing becomes small,
and thus the bearing rigidity may be reduced. When the bearing
rigidity decreases, a tilting of a rotation shaft of a rotating
body when off-center load is applied thereto may become large, and
in the worst case, the rotating body contacts a stationary body,
which is cause of breakdown. Hence, in order to compensate the
reduction of the rigidity of the radial dynamic bearing part due to
thinning, a thrust radial dynamic bearing part is provided at a
relatively distant location from the rotation center, and the
bearing rigidity of the thrust dynamic bearing part should be
enhanced.
[0007] Such a technical problem is also common to other kinds of
rotating devices and is not particular to disk drive devices.
[0008] The present disclosure has been made in view of the
aforementioned circumstances, and it is an objective of the present
disclosure to provide a rotating device that enhances the bearing
rigidity of a thrust dynamic bearing part, thus advantageous for
thinning.
SUMMARY OF THE INVENTION
[0009] To accomplish the above objective, a rotating device
according to a first aspect of the present disclosure includes: a
retained assembly including a spherical retained member with a
spherical encircled face, and a first encircling member that
includes an annular end face which encircles the spherical retained
member and which extends outwardly in a radial direction; a
retainer assembly including a retainer member which includes an
encircling face encircling the encircled face and which retains
thereinside a part of the spherical retained member, and a facing
member that faces the first encircling member in an axial
direction, the retainer assembly supporting the retained assembly
in a freely and relatively rotatable manner, and forming a fluid
dynamic bearing mechanism; and a first thrust dynamic pressure
generating groove formed in at least either one of a surface of the
first encircling member and a surface of the facing member, which
surfaces face with each other in the axial direction.
[0010] To accomplish the above objective, a rotating device
according to a second aspect of the present disclosure includes: a
retained assembly including a retained member in a truncated cone
shape having a tapered encircled face, and a first encircling
member that includes an annular end face which encircles the
truncated conical retained member and which extends outwardly in a
radial direction; a retainer assembly including a retainer member
which includes an encircling face encircling the encircled face and
which retains thereinside apart of the truncated conical retained
member, and a facing member that faces the first encircling member
in an axial direction, the retainer assembly supporting the
retained assembly in a freely and relatively rotatable manner, and
forming a fluid dynamic bearing mechanism; and a first thrust
dynamic pressure generating groove formed in at least either one of
a surface of the first encircling member and a surface of the
facing member, which surfaces face with each other in the axial
direction.
[0011] To accomplish the above objective, a rotating device
according to a third aspect of the present disclosure includes: a
retained assembly including a retained member that has a spherical
or tapered encircled face, and an encircling member that includes
an annular end face which encircles the retained member and which
extends outwardly in a radial direction; a retainer assembly
including a retainer member which includes an encircling face
encircling the encircled face and which retains thereinside a part
of the retained member, and a facing member that faces the
encircling member in an axial direction, the retainer assembly
supporting the retained assembly in a freely and relatively
rotatable manner, and forming a fluid dynamic bearing mechanism; a
thrust dynamic pressure generating groove formed in at least either
one of a surface of the encircling member and a surface of the
facing member, which surfaces face with each other in the axial
direction; a rotating body which is supported by the fluid dynamic
bearing mechanism and which is fixed with a vane that creates wind
when rotated; and a drive mechanism that rotates the rotating
body.
[0012] Arbitrary combinations of the aforementioned structural
elements and mutual replacement of the structural elements and
expressions of the present disclosure among a method, a device, and
a system are also effective as an embodiment of the present
disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIGS. 1A and 1B are a top view and a side view illustrating
a rotating device according to a first embodiment;
[0014] FIG. 2 is a cross-sectional view taken along a line A-A in
FIG. 1A;
[0015] FIG. 3 is a cross-sectional view illustrating a rotating
device according to a second embodiment;
[0016] FIG. 4A is a cross-sectional view taken along a line B-B in
FIG. 3, FIG. 4B is a cross-sectional view taken along a line C-C in
FIG. 3, and FIG. 4C is a cross-sectional view taken along a line
D-D in FIG. 3;
[0017] FIG. 5 is a cross-sectional view illustrating a rotating
device according to a third embodiment;
[0018] FIG. 6 is a cross-sectional view illustrating a rotating
device according to a fourth embodiment;
[0019] FIG. 7 is a cross-sectional view illustrating a rotating
device according to a fifth embodiment;
[0020] FIG. 8 is a cross-sectional view illustrating a rotating
device according to a sixth embodiment;
[0021] FIG. 9 is a cross-sectional view illustrating a rotating
device according to a modified example;
[0022] FIG. 10 is a diagram illustrating a top of a fan motor and a
side thereof according to an embodiment; and
[0023] FIG. 11 is a cross-sectional view taken along a line A-A in
FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] The same or corresponding structure, and component in
respective figures will be denoted by the same reference numeral,
and the duplicated explanation thereof will be omitted accordingly.
The dimension of a component in each figure is enlarged or scaled
down as needed to facilitate understanding. Apart of a component
not important to explain an embodiment will be omitted in each
figure.
[0025] A rotating device according to an embodiment is suitably
utilized as a disk drive device, in particular, a hard disk drive
loaded with a magnetic recording disk and rotating and driving such
a recording disk, and a fan motor that rotates to produce wind.
First Embodiment
[0026] FIGS. 1A and 1B illustrate a rotating device 100 according
to a first embodiment. FIG. 1A is a top view of the rotating device
100. FIG. 1B is a side view of the rotating device 100. In FIG. 1A,
a top cover 2 is detached to illustrate the internal structure of
the rotating device 100. The rotating device 100 includes a
stationary body, a rotating body that rotates relative to the
stationary body, a magnetic recording disk 8 to be mounted on the
rotating body, and a data reader/writer 10. The stationary body
includes a base 4, the top cover 2, and six screws 20. The rotating
body includes a hub 28, a clamper 36, and a cap 12.
[0027] In the following explanation, a side at which the hub 28 is
mounted relative to the base 4 will be defined as an upper
side.
[0028] The magnetic recording disk 8 is, for example, a 2.5-inch
magnetic recording disk formed of glass, and having a diameter of
65 mm. The diameter of a center hole is 20 mm, and the thickness is
0.65 mm. The magnetic recording disk 8 is to be mounted on the hub
28, and is rotated together with a rotation of the hub 28.
[0029] The base 4 is formed and shaped by, for example, die-casting
of an aluminum alloy. The base 4 includes a bottom portion 4a
forming the bottom of the rotating device 100, and an outer
circumference wall 4b formed along the outer circumference of the
bottom portion 4a so as to encircle an area where the magnetic
recording disk 8 is placed. Six screw holes 22 are provided in an
upper face 4c of the outer circumference wall 4b. The base 4 may be
formed by pressing of a steel sheet or an aluminum sheet. In this
case, the base 4 may include an embossed portion such that one
surface of the base 4 may be raised to form a convexity, and
another surface may be formed with a concavity corresponding to
that convexity. By providing an embossed portion at a predetermined
location, a deformation of the base 4 can be suppressed. In
addition, the base 4 may be a combination of a sheet-metal portion
formed by pressing and a die-cast portion formed and shaped by
aluminum die-casting.
[0030] A surface coating is applied to the base 4 in order to
suppress a peeling from the surface thereof. An example surface
coating applied is a resin-material coating like an epoxy resin.
Alternatively, a surface coating may be a coating formed by plating
a metal material, such as nickel or chrome. In this embodiment, the
base 4 has the surface having undergone electroless nickel plating.
In comparison with a case in which the resin material is applied as
a coating, the surface hardness is enhanced to decrease a friction
coefficient. Hence, when, for example, the magnetic recording disk
8 contacts the surface of the base 4 at the time of manufacturing,
the possibility that the surface of the base 4 and the magnetic
recording disk 8 are damaged can be reduced. In this embodiment,
the surface of the base 4 has a static friction coefficient within
a range from 0.1 to 0.6. In comparison with a case in which the
static friction coefficient is equal to or greater than 2, the
possibility that the base 4 and the magnetic recording disk 8 are
damaged can be further reduced.
[0031] The data reader/writer 10 includes an unillustrated
recording/playing head, a swing arm 14, a voice coil motor 16, and
a pivot assembly 18. The recoding/playing head is attached to the
tip of the swing arm 14, records data in the magnetic recording
disk 8, or reads the data therefrom. The pivot assembly 18 supports
the swing arm 14 in a swingable manner to the base 4 around a head
rotating axis S. The voice coil motor 16 allows the swing arm 14 to
swing around the head rotating axis S to move the recording/playing
head to a desired location over the top face of the magnetic
recording disk 8. The voice coil motor 16 and the pivot assembly 18
are configured by a conventionally well-known technology of
controlling the position of a head.
[0032] The top cover 2 is fastened to the upper face 4c of the
outer circumference wall 4b of the base 4 using six screws 20. The
six screws 20 correspond to the six screw holes 22. In particular,
the top cover 2 and the upper face 4c of the outer circumference
wall 4b are fastened together in such a way that no leak to the
interior of the rotating device 100 occurs from the joined portion
therebetween.
[0033] FIG. 2 is a cross-sectional view taken along a line A-A in
FIG. 1A.
[0034] The rotating body includes the hub 28, a retained member 26,
a retained-member holder 90, a first thrust member 30, a second
thrust member 31, the clamper 36, a cylindrical magnet 32, and the
cap 12. The stationary body includes the base 4, a retainer member
24, a flange member 34, a stator core 40, coils 42, an insulation
tape 44, and an attracting plate 46. A lubricant 48 is continuously
applied in a part of gaps between the rotating body and the
stationary body.
[0035] The hub 28 is formed by, for example, cutting and machining
or pressing a ferrous material with a soft magnetism like SUS 430
or SUS 303, and is formed in a predetermined shape like a
substantially cup shape. In order to suppress a peeling from the
surface of the hub 28, a surface layer forming process like
electroless nickel plating may be applied to the surface of the hub
28.
[0036] The hub 28 includes a hub protrusion 28a to be engaged with
the center hole 8a of the magnetic recording disk 8, and a mount
portion 28b provided outwardly in the radial direction relative to
the hub protrusion 28a. The magnetic recording disk 8 is to be
mounted on a disk mount face 28c that is the upper face of the
mount portion 28b. The magnetic recording disk 8 is held between
the clamper 36 and the mount portion 28b, thereby being fastened to
the hub 28.
[0037] The clamper 36 applies downward force in the axial direction
to the upper face of the magnetic recording disk 8 to cause the
magnetic recording disk 8 to be in contact with the disk mount face
28c with pressure. The clamper 36 is engaged with an outer
circumference 28d of the hub protrusion 28a. The clamper 36 and the
outer circumference 28d of the hub protrusion 28a can be joined
together by mechanical joining techniques, such as screwing,
caulking, and press-fitting, or a magnetic joining technique
utilizing magnetic suction force.
[0038] The clamper 36 is disposed in such a way that, with the
clamper 36 applying desired downward force to the magnetic
recording disk 8, an upper face 36a of the clamper 36 does not
protrude upwardly beyond an upper face 28e of the hub protrusion
28a.
[0039] When, for example, a structure is employed in which the
clamper 36 and the outer circumference 28d of the hub protrusion
28a are engaged by screwing, a male screw is formed on the outer
circumference 28d of the hub protrusion 28a, while a counterpart
female screw is formed in an inner circumference 36b of the clamper
36. In this case, depending on the strength of the screwing, the
tension of the downward force applied by the clamper 36 to the
upper face of the magnetic recording disk 8 can be relatively
precisely adjusted. The clamper 36 may be formed of multiple
pieces, or may be a single piece.
[0040] If process burrs are sticking to the outer circumference 28d
of the hub protrusion 28a, when the clamper 36 is engaged with the
outer circumference 28d by screwing, the clamper 36 may contact the
process burrs and the process burrs are peeled. In order to
eliminate such process burrs in advance, a burr eliminating process
may be applied to the outer circumference 28d of the hub protrusion
28a.
[0041] The first thrust member 30 is provided on the lower face of
the hub protrusion 28a so as to encircle the retainer member 24.
The first thrust member 30 is formed in an annular shape, and is
formed of a metal, such as a ferrous material like SUS 430 or SUS
303, or a copper alloy. The first thrust member 30 is formed
integrally with the hub 28. The first thrust member 30 and the hub
28 may be formed separately, and then joined with each other.
[0042] The retained-member holder 90 is provided at an
inner-circumference-28g side of the hub protrusion 28a. The
retained-member holder 90 is formed in an annular shape, and is
formed of a metal, such as a ferrous material like SUS 430 or SUS
303, or a copper alloy. The retained-member holder 90 is formed
with a hole 90a provided coaxially with a rotation axis R of the
rotating body. The retained-member holder 90 is formed integrally
with the hub 28. The retained-member holder 90 may be formed
separately from the hub 28, and then joined with each other.
[0043] As an example, the retained member 26 is formed of a ferrous
material like SUJ2 or ceramics. The retained member 26 is formed in
a solid shape obtained by rotating, around the rotation axis R, a
plane having the rotation axis R of the rotating body as a side. In
this embodiment, the retained member 26 is formed as a solid
obtained by rotating, around the rotation axis R, a semi circle
having the rotation axis R as a diameter. That is, the retained
member 26 is formed in a spherical shape. Hence, a side face 26b of
the retained member 26 forms a spherical surface, and encircled by
the retainer member 24 as will be discussed later. The retained
member 26 is fixed to the retained-member holder 90 by bonding or
welding with apart of the retained member entering in the hole 90a
of the retained-member holder 90. In particular, the retained
member 26 is fixed to the retained-member holder 90 in such a way
that a center C of the retained member is located on the rotation
axis R. The retained member 26 may be held in a non-fixed manner
with the retained-member holder 90.
[0044] The cylindrical magnet 32 is bonded and fastened to a
cylindrical inner circumference 28f of the hub 28 corresponding to
the internal cylindrical face thereof. The cylindrical magnet 32 is
formed of, for example, a rare-earth magnetic material or a ferrite
magnetic material. In this embodiment, the cylindrical magnet 32 is
formed of a neodymium-based rare-earth magnetic material. The
cylindrical magnet 32 has 12 driving polarities in the
circumferential direction thereof (a tangent line direction of a
vertical circle to the rotation axis R and around it). The
cylindrical magnet 32 faces nine salient poles of the stator core
40 in the radial direction. An anti-corrosion process, such as
electrodeposition coating or spray coating is applied to the
surface of the cylindrical magnet 32.
[0045] The stator core 40 includes an annular part and the nine
salient poles extending therefrom outwardly in the radial
direction, and is fixed on an upper-face-4d side of the base 4. The
stator core 40 is formed by, for example, laminating six thin
magnetic steel sheets each having a thickness of 0.2 mm, and
caulking and integrating those sheets together. The stator core 40
may be formed by laminating, for example, 2 to 32 thin magnetic
steel sheets each having a thickness of 0.1 to 0.8 mm. An
insulation coating is applied to the surface of the stator core 40
by, for example, electrodeposition coating or powder coating. A
coil 42 is wound around each salient pole of the stator core 40.
When three-phase substantially sinusoidal drive currents are caused
to flow through the respective coils 42, drive magnetic fluxes are
generated along the salient poles. The stator core 40 may be formed
by solidifying magnetic powder materials like an sintered body.
[0046] The base 4 includes an annular base protrusion 4e around the
rotation axis R of the rotating body. The base protrusion 4e
protrudes upwardly so as to encircle the second thrust member 31.
When a center hole 40a of the annular part of the stator core 40 is
engaged with an outer circumference 4f of the base protrusion 4e,
the stator core 40 is fixed to the base 4. In particular, the
annular part of the stator core 40 is bonded and fixed to the base
protrusion 4e by press-fitting or loose fitting.
[0047] The insulation tape 44 or a resin-made insulation sheet like
PET is provided at a portion of the upper face 4d of the base 4
corresponding to the salient poles and the coils 42. The attracting
plate 46 formed of a magnetic material like iron is provided at a
portion of the upper face 4d of the base 4 facing with the
cylindrical magnet 32 in the axial direction (a direction parallel
to the rotation axis R). The attracting plate 46 is fixed to the
base 4 by caulking or bonding. The attracting plate 46 attracts the
cylindrical magnet 32 by magnetic force, and thus downward force in
the axial direction is applied to the cylindrical magnet 32. Such a
force suppresses a floating of the rotating body while the rotating
body is rotating.
[0048] The base 4 is provided with a non-through-hole type hole 4g
around the rotation axis R of the rotating body. The hole 4g may be
a through-hole. The retainer member 24 is fitted in and fixed to
the hole 4g. The retainer member 24 supports the retained member 26
in a freely rotatably manner via the lubricant 48. Hence, the
rotating body is supported in a freely rotatable manner relative to
the base 4.
[0049] The retainer member 24 is formed in a cup shape with a
bottom having a hollow barrel portion 24a and a bottom portion 24b
formed integrally with each other, and is fixed to the base 4 by,
for example, bonding with the bottom portion 24b placed downwardly.
The hollow barrel portion 24a has cylindrical inner circumference
24c. The retained member 26 is retained in the retainer member 24,
and the inner circumference 24c encircles a side face 26b of the
retained member 26 via a radial gap 53.
[0050] The second thrust member 31 is provided so as to encircle
the retainer member 24. The second thrust member 31 includes a
cylindrical part 31a and a flange part 31b extending inwardly in
the radial direction from the lower end of the cylindrical part
31a, and the second thrust member 31 has an L-shaped cross-section.
The second thrust member 31 encircles the first thrust member 30,
and fixed to an outer circumference 30c of the first thrust member
30. The second thrust member 31 is fixed to the first thrust member
30 by a combination of press-fitting and bonding. A bond between
the second thrust member 31 and the first thrust member 30 seals a
gap between the second thrust member 31 and the first thrust member
30, and serves as a sealant preventing the lubricant 48 from
leaking out.
[0051] The flange member 34 is formed in an annular shape, and is
provided at the outer-circumference-24d side of the retainer member
24. The flange member 34 is formed integrally with the retainer
member 24. The flange member 34 may be a separate piece from the
retainer member 24. In this case, the flange member 34 may be
formed of a different material from that of the retainer member 24.
A lower face 30d of the first thrust member 30, an inner
circumference 31c of the cylindrical part 31a, and an upper face
31d of the flange part 31b form an annular recess 60 concaved
outwardly in the radial direction. The flange member 34 is retained
in this recess 60. An upper face 34a of the flange member 34 and
the lower face 30d of the first thrust member 30 face with each
other in the axial direction via a first thrust gap 57 in an
annular shape. In addition, a lower face 34b of the flange member
34 and the upper face 31d of the flange part 31b face with each
other in the axial direction via a second thrust gap 58 in an
annular shape.
[0052] Formed between the flange part 31b of the second thrust
member 31 and the retainer member 24 is a tapered seal 70 where a
gap 72 between an inner circumference 31e of the flange part 31b
and an outer circumference 24d of the retainer member 24 gradually
becomes widespread downwardly, i.e., toward a space where gas like
air is present at an outlet side. In view of other aspects, the gap
of the tapered seal 70 becomes widespread from a bottom side where
the lubricant 48 is present to the outlet side. In particular, both
of the inner circumference 31e of the flange part 31b and the outer
circumference 24d of the retainer member 24 are formed so as to
decrease the diameter toward the bottom, and the diameter
decreasing rate of the inner circumference 31e of the flange part
31b is smaller than the diameter decreasing rate of the outer
circumference 24d of the retainer member 24, thereby realizing the
tapered shape of the tapered seal 70. In addition, the tapered seal
70 has the bottom area formed at a more distant location from the
rotation axis R than the outlet area. When the rotating body
rotates, outward force in the radial direction due to centrifugal
force is applied to the lubricant 48 in the tapered seal 70. Since
the tapered seal 70 has the bottom area located outwardly in the
radial direction relative to the outlet area, such force acts so as
to push the lubricant 48 toward the bottom area. The tapered seal
70 has a gas-liquid interface 86 of the lubricant 48, and serves as
a capillary seal that suppresses a leak-out of the lubricant 48 by
capillary force.
[0053] The cap 12 is formed of a metal like stainless-steel or a
resin and in a substantially disk shape. The cap 12 is fixed to an
upper face 90b of the retained-member holder 90 so as to block off
the upper end of the hole 90a of the retained-member holder 90 by,
for example, bonding.
[0054] The lubricant 48 is continuously present in a backward area
from the gas-liquid interface 86 in the gap between the rotating
body and the stationary body. In particular, the lubricant 48 is
applied in gaps between the retained member 26, the first thrust
member 30, and the second thrust member 31 which are parts of the
rotating body, and the retainer member 24 and the flange member 34
which are parts of the stationary body. The lubricant 48 contains a
fluorescent material. When light like ultraviolet ray is emitted to
the lubricant 48, the lubricant 48 emits, for example, blue or
green light with a different wavelength from that of the emitted
light because of the behavior of the fluorescent material. Since
the lubricant 48 contains such a fluorescent material, it becomes
easy to inspect the fluid level of the lubricant 48. In addition,
sticking of the lubricant 48 to an improper location and leakage of
the lubricant 48 can be easily detected.
[0055] The upper face 34a of the flange member 34 includes a first
thrust dynamic pressure generating groove formed area 63. The first
thrust dynamic pressure generating groove formed area 63 is formed
with first thrust dynamic pressure generating grooves 55 in a
spiral shape or a herringbone shape. The first thrust dynamic
pressure generating grooves 55 may be formed in the lower face 30d
of the first thrust member 30 instead of the first thrust dynamic
pressure generating groove formed area 63 or in addition
thereto.
[0056] A lower face 34b of the flange member 34 includes a second
thrust dynamic pressure generating groove formed area 64. The
second thrust dynamic pressure generating groove formed area 64 is
formed with second thrust dynamic pressure generating grooves 56 in
a spiral shape or a herringbone shape. The second thrust dynamic
pressure generating grooves 56 may be formed in the upper face 31d
of the flange part 31b of the second thrust member 31 instead of
the second thrust dynamic pressure generating groove formed area 64
or in addition thereto. Still further, a structure having no second
thrust dynamic pressure generating groove formed area 64, i.e.,
having no second thrust dynamic pressure generating grooves 56 can
be employed.
[0057] The first thrust dynamic pressure generating grooves 55 and
the second thrust dynamic pressure generating grooves 56 generate
fluid dynamic pressures in the lubricant 48 when the rotating body
rotates relative to the stationary body. In particular, the first
thrust dynamic pressure generating grooves 55 and the second thrust
dynamic pressure generating grooves 56 generate fluid dynamic
pressures in a so-called pump-in direction in which the generated
synthetic dynamic pressures push the lubricant 48 toward the
rotation axis R. The dynamic pressures in the pump-in direction
produce floating force in a first thrust gap 57 between the first
thrust member 30 and the flange member 34, a second thrust gap 58
between the second thrust member 31 and the flange member 34, and a
gap between the retained member 26 and the retainer member 24 in a
separating direction from each other.
[0058] An inner circumference 24c of the hollow barrel portion 24a
includes a radial dynamic pressure generating groove formed area
62. The radial dynamic pressure generating groove formed area 62 is
formed with radial dynamic pressure generating grooves 50 in a
spiral or herringbone shape. The radial dynamic pressure generating
grooves 50 generate fluid dynamic pressure in the lubricant 48 in
the radial direction when the rotating body rotates relative to the
stationary body. The fluid dynamic pressure in the radial direction
acts so as to maintain a radial gap 53 between the retainer member
24 and the retained member 26 to be substantially constant. That
is, the retained member 26 is positioned so as to have a center C
thereof located on the center axis of the cylindrical inner
circumference 24c by the fluid dynamic pressure in the radial
direction. The radial dynamic pressure generating grooves 50 may be
formed in the retained member 26 instead of the radial dynamic
pressure generating groove formed area 62 or in addition
thereto.
[0059] The first thrust dynamic pressure generating groove formed
area 63 is an annular band-like area encircling the rotation axis
R, and is formed so as to be substantially orthogonal to the axial
direction. That is, the first thrust dynamic pressure generating
groove formed area 63 is a disk-like area around the rotation axis
R. The first thrust dynamic pressure generating groove formed area
63 is formed in such a way that a difference in radii between the
inscribed circle and the circumscribed circle becomes larger than
the dimension of the radial dynamic pressure generating groove
formed area 62 in the axial direction. According to this structure,
in comparison with a case not so, the fluid dynamic pressure
generated by the first thrust dynamic pressure generating grooves
55 becomes large, and thus the bearing rigidity of the thrust
dynamic bearing is enhanced. When the bearing rigidity of the
thrust dynamic bearing is enhanced, even if, for example,
off-center load is applied to the rotating body and moment force is
applied to the rotating body relative to the rotation axis R, a
tilting relative to the rotation axis R can be suppressed. When the
rotating device is made thin, the first thrust dynamic pressure
generating groove formed area 63 is not decreased, and thus a
reduction of the fluid dynamic pressure generated by the first
thrust dynamic pressure generating grooves 55 and that of the
bearing rigidity can be suppressed. The same is true of the second
thrust dynamic pressure generating groove formed area 64.
[0060] The rotating body and the stationary body are structured in
such a way that a weight center G of the rotating body is located
at the center C of the retained member 26 when the magnetic
recording disk 8 is mounted on the hub 28.
[0061] An explanation will be given of an operation of the rotating
device 100 employing the above-explained structure. Three-phase
drive currents are applied to the coils 42 to rotate the magnetic
recording disk 8. When such drive currents flow through the
respective coils 42, magnetic fluxes are generated along the nine
salient poles. Those magnetic fluxes apply torque to the
cylindrical magnet 32, and thus the hub 28 and the magnetic
recording disk 8 engaged therewith rotate. While at the same time,
when the voice coil motor 16 causes the swing arm 14 to swing, the
recording/playing head goes out and comes in the swingable range
over the magnetic recording disk 8. The recording/playing head
converts magnetic data recorded in the magnetic recording disk 8
into electrical signals, and transmits the signals to a control
board (unillustrated), or writes data transmitted in the form of
electrical signals from the control board in the magnetic recording
disk 8 as magnetic data.
[0062] According to the rotating device 100 of this embodiment, the
retained member 26 is formed in a spherical shape. According to the
experiences of the inventors as persons skilled in the art, for
example, a spherical member formed of a ferrous material can
relatively easily accomplish a high form accuracy. Hence, according
to the rotating device 100 utilizing the spherical retained member
26, when the rotating device 100 is made thin, a reduction of the
rotation precision can be suppressed. In addition, the costs of the
rotating device 100 can be reduced.
[0063] In addition, according to the rotating device 100 of this
embodiment, the fluid dynamic pressure generated by the first
thrust dynamic pressure generating grooves 55 is relatively large.
Hence, it is sufficient for the radial dynamic pressure generating
grooves 50 if the radial dynamic pressure generating grooves 50
mainly accomplishes a centering. Therefore, the number of radial
dynamic pressure generating groove formed areas 62 can be one, and
the dimension thereof in the axial direction can be made relatively
small. As a result, the dimension of the rotating device 100 in the
axial direction can be made relatively small. For example, the
dimension of the rotating device 100 in the axial direction can be
equal to or smaller than 4.1 mm.
Second Embodiment
[0064] The major difference between a rotating device of a second
embodiment and the rotating device 100 of the first embodiment is
the shape of the retainer member.
[0065] FIG. 3 is a cross-sectional view illustrating a rotating
device 200 of the second embodiment. FIG. 3 corresponds to FIG. 2.
The rotating body includes the hub 28, the retained member 26, the
retained-member holder 90, the first thrust member 30, the second
thrust member 31, the clamper 36, the cylindrical magnet 32, and
the cap 12. The stationary body includes the base 4, a retainer
member 124, the flange member 34, the stator core 40, the coils 42,
the insulation tape 44, and the attracting plate 46.
[0066] The retainer member 124 is formed in a cup shape with a
bottom in such a way that a hollow barrel portion 124a is formed
integral with the bottom 24b. The hollow barrel portion 124a has a
cylindrical inner circumference 124c. In particular, the inner
circumference 124c is formed in a cylindrical shape having a center
axis tilted by an angle .theta. relative to the rotation axis R.
The retained member 26 is retained in the retainer member 124, and
the inner circumference 124c encircles the side face 26b via a
radial gap 153. When the rotating body is still, the inner
circumference 124c and the side 26b of the retained member 26 at
least partially contact with each other.
[0067] FIG. 4A is a cross-sectional view taken along a line B-B in
FIG. 3, FIG. 4B is a cross-sectional view taken along a line C-C in
FIG. 3, and FIG. 4C is a cross-sectional view taken along a line
D-D in FIG. 3. As is clear from FIGS. 4A to 4C, the retained member
26 is decenterized in opposite directions with the cut plane in
FIG. 4A and the cut plane in FIG. 4C relative to the inner
circumference 124c of the retainer member 124. Hence, dynamic
pressure becomes relatively large at the respective narrowed gaps,
and thus respective synthesis dynamic pressures in the B-B
cross-sectional view and the D-D cross-sectional view are generated
at the positions indicated by the alphabet P. That is, in the cases
of the cut plane in FIG. 4A and the cut plane in FIG. 4C, synthesis
dynamic pressures P in opposite directions are generated. The
smaller the gap is, the larger the dynamic pressure P becomes, and
the larger the gap is, the smaller the dynamic pressure P becomes.
Hence, a balancing is accomplished with a gap condition in which
the two dynamic pressures P are substantially equal, and thus an
autonomous centering mechanism which makes the gap 153 between the
retainer member 124 and the retained member 26 substantially
uniform is accomplished. That is, the retained member 26 is
positioned so as to have the center C thereof located on the center
axis of the cylindrical inner circumference 124c by the fluid
dynamic pressure in the radial direction.
[0068] Since the B-B cross-sectional view and the D-D
cross-sectional view are offset in the axial direction, the dynamic
pressure P in the B-B cross-sectional view has downward component
force, while the dynamic pressure P in the D-D cross-sectional view
has upward component force. Such upward component force and
downward component force act on the retained member 26 so as to
suppress a displacement in the axial direction. As a result, the
retained member 26 is supported by the dynamic pressure P in the
radial direction and the axial direction, thereby accomplishing a
further stable rotation.
[0069] According to the rotating device 200 of this embodiment, the
same advantageous effects as those of the rotating device 100 of
the first embodiment can be accomplished.
Third Embodiment
[0070] The major differences between a rotating device of a third
embodiment and the rotating device 100 of the first embodiment are
the shape of the base and that of the second thrust member.
[0071] FIG. 5 is a cross-sectional view illustrating a rotating
device 300 of the third embodiment. FIG. 5 corresponds to FIG. 2.
The rotating body includes the hub 28, the retained member 26, the
retained-member holder 90, the first thrust member 30, a second
thrust member 231, the clamper 36, the cylindrical magnet 32, and
the cap 12. The stationary body includes a base 204, the retainer
member 24, the flange member 34, the stator core 40, the coils 42,
the insulation tape 44, and the attracting plate 46.
[0072] The second thrust member 231 includes the cylindrical part
31a and a flange part 231b extending inwardly in the radial
direction from the lower end of the cylindrical part 31a. The
flange part 231b is, unlike the flange part 31b of the first
embodiment, formed with an annular thrust recess 231f concaved
upwardly in the direction of the rotation axis R from the outer
edge of the lower end of the flange part 231b.
[0073] The base 204 is provided with a through-hole 204g around the
rotation axis R of the rotating body. The retainer member 24 is
fitted in and fixed to the through-hole 204g. In addition, the base
204 includes an entering part 204h entering in the thrust recess
231f.
[0074] A gap 88 between the second thrust member 31 and the base
204 is in communication with a motor internal space 84 held between
the hub 28 and the base 204, and the gas side of the gas-liquid
interface 86. That is, the gap 88 causes the gas-liquid interface
86 to be in communication with the motor internal space 84. As
explained above, since the flange part 231b has the thrust recess
231f, and the base 204 has the entering part 204h entering the
thrust recess 231f, the gap 88 is made so as to have a narrow width
but a long length. In addition, the gap 88 is provided with
multiple bent portions. Hence, the channel resistance of the gap 88
can be increased.
[0075] According to the rotating device 300 of this embodiment, the
same advantageous effects as those of the rotating device 100 of
the first embodiment can be accomplished. In addition, according to
the rotating device 300 of this embodiment, the gap 88 between the
second thrust member 31 and the base 204 has a narrowed width but a
long length. In addition, the gap 88 is provided with multiple bent
portions. Therefore, the channel resistance of the gap 88 can be
increased. Accordingly, the gap 88 serves as a labyrinth to the
lubricant 48 vaporized from the gas-liquid interface 86 of the
tapered seal 70, thereby reducing the quantity of the dissipated
lubricant 48.
Fourth Embodiment
[0076] The major differences of a rotating device of a fourth
embodiment from the rotating device 100 of the first embodiment are
the shape of the retained member and that of the retainer
member.
[0077] FIG. 6 is a cross-sectional view illustrating a rotating
device 400 of the fourth embodiment. FIG. 6 corresponds to FIG. 2.
The rotating body includes the hub 28, a retained member 326, a
retained-member holder 390, a first thrust member 330, the second
thrust member 31, the clamper 36, and the cylindrical magnet 32.
The stationary body includes the base 4, the retainer member 324,
the flange member 34, the stator core 40, the coils 42, the
insulation tape 44, and the attracting plate 46.
[0078] Provided at an inner-circumference-28g side of the hub
protrusion 28a is the retained-member holder 390. Unlike the
retained-member holder 90 of the first embodiment, the
retained-member holder 390 is formed in a disk shape.
[0079] The retained member 326 is formed of a metal, such as a
ferrous material like SUS 430 or SUS 303, or a copper alloy. The
retained member 326 is formed in a truncated cone shape, and is
fixed to the retained-member holder 390 so as to align the center
axis of the truncated cone with the rotation axis R. Hence, a side
face 326b of the retained member 326 is formed in a truncated cone
shape. The retained member 326 may be formed integrally with the
first thrust member 330.
[0080] The retainer member 324 is formed in a cup shape with a
bottom in such a way that a hollow barrel portion 324a and a bottom
324b are formed integrally, and is fixed to the base 4 by, for
example, bonding with the bottom 324b directed downwardly. The
hollow barrel 324a has an inner circumference 324c formed in a
truncated cone shape. The retained member 326 is retained in the
retainer member 324, and the inner circumference 324c encircles the
side face 326b of the retained member 326 with a radial gap
353.
[0081] According to the rotating device 400 of this embodiment, the
same advantageous effects as those of the rotating device 100 of
the first embodiment can be accomplished.
Fifth Embodiment
[0082] In the first to fourth embodiments, the explanation was
given of an example case in which the retained member is fixed to
the rotating body. In a fifth embodiment, however, an explanation
will be given of an example case in which the retained member is
fixed to the stationary body.
[0083] FIG. 7 is a cross-sectional view illustrating a rotating
device 500 of the fifth embodiment. FIG. 7 corresponds to FIG. 5.
The rotating body includes the hub 28, a retainer member 424, the
first thrust member 30, the second thrust member 231, the clamper
36, the cylindrical magnet 32, and the cap 12. The stationary body
includes the base 204, a retained-member holder 490, the flange
member 34, a retained member 426, the stator core 40, the coils 42,
the insulation tape 44, and the attracting plate 46.
[0084] The retained-member holder 490 is formed in a substantially
cylindrical shape, and is formed of a metal, such as a ferrous
material like SUS 430 or SUS 303 or a copper alloy. The
retained-member holder 490 is fitted in and fixed to a through-hole
204g of the base 204. A holding recess 490b is formed in an upper
face 490a of the retained-member holder 490. The retained-member
holder 490 is fixed with the flange member 34. In particular, the
flange member 34 is fixed to the retained-member holder 490 so as
to encircle the retainer member 424.
[0085] The retained member 426 is formed of a ferrous material like
SUJ2 or a ceramic. The retained member 426 is formed in a spherical
shape, and is fixed to the retained-member holder 490 by bonding or
welding with a part of the retained member 426 entering in the
holding recess 490b. In particular, the retained member 426 is
fixed to the retained-member holder 490 so as to position a center
C of the retained member 426 on the rotation axis R.
[0086] The retainer member 424 is joined with the circumference of
a hole 30b of the first thrust member 30. The retainer member 424
is formed in a cylindrical shape, and is formed of a ferrous
material like SUS 430 or SUS 303, or a copper alloy. The retained
member 426 is retained in the retainer member 424. An inner
circumference 424c of the retainer member 424 is formed in a
cylindrical shape, and encircles a side face 426b of the retained
member 426 with a radial gap 453. The retainer member 424 may be
formed integrally with the first thrust member 30.
[0087] Formed between a flange part 231b of the second thrust
member 231 and the retained-member holder 490 is a tapered seal 470
where a gap 472 between an inner circumference 31e of the flange
part 231b and an outer circumference 490c of the retained-member
holder 490 gradually becomes widespread downwardly. The tapered
seal 470 corresponds to the tapered seal 70 of the third
embodiment.
[0088] The cap 12 is fixed to an upper face 424a of the retainer
member 424 by, for example, bonding so as to block off the upper
space of the retainer member 424.
[0089] The lubricant 48 is applied in a gap between a part of the
rotating body that is the retainer member 424, the first thrust
member 30, the cap 12, and the second thrust member 231, and, a
part of the stationary body that is the retained member 426 and the
retained-member holder 490.
[0090] The inner circumference 424c of the retainer member 424
includes a radial dynamic pressure generating groove formed area
462. The radial dynamic pressure generating groove formed area 462
is formed with radial dynamic pressure generating grooves 450 in a
spiral or herringbone shape. The radial dynamic pressure generating
groove formed area 462 and the radial dynamic pressure generating
grooves 450 correspond to the radial dynamic pressure generating
groove formed area 62 and the radial dynamic pressure generating
groove 50 of the third embodiment.
[0091] According to the rotating device 500 of this embodiment, the
same advantageous effects as those of the rotating device 300 of
the third embodiment can be accomplished.
Sixth Embodiment
[0092] The major differences of a rotating device according to a
sixth embodiment from the rotating device 500 of the fifth
embodiment are the shape of the retained member and that of the
retainer member.
[0093] FIG. 8 is a cross-sectional view illustrating a rotating
device 600 of the sixth embodiment. FIG. 8 corresponds to FIG. 7.
The rotating body includes the hub 28, a retainer member 524, the
first thrust member 30, the second thrust member 231, the clamper
36, the cylindrical magnet 32, and the cap 12. The stationary body
includes the base 204, the retained-member holder 490, the flange
member 34, a retained member 526, the stator core 40, the coils 42,
the insulation tape 44, and the attracting plate 46.
[0094] The retained member 526 is formed of a metal material, such
as a ferrous material like SUS 430 or SUS 303 or a copper alloy.
The retained member 526 is formed in a truncated cone shape, and is
fixed to the first thrust member 30 so as to position the center
axis of the retained member 526 on the rotation axis R. Hence, a
side face 526b of the retained member 526 is formed in a truncated
cone shape. The retained member 526 may be formed integrally with
the retained-member holder 490.
[0095] The retainer member 524 is formed in a cylindrical shape.
The retained member 526 is retained in the retainer member 524, and
an inner circumference 524c encircles the side face 526b of the
retained member 526 with a radial gap 553. The inner circumference
524c includes a tapered face decreasing the diameter toward the
bottom. When the rotating body stands still, the inner
circumference 524c and the side face 526b of the retained member
526 at least partially contact with each other.
[0096] According to the rotating device 600 of this embodiment, the
same advantageous effects as those of the rotating device 500 of
the fifth embodiment can be accomplished.
Seventh Embodiment
[0097] A rotating device 1100 according to a seventh embodiment is
in the form of a fan motor. FIG. 10 illustrates the top view of the
rotating device 1100 and the side view thereof, and FIG. 11 is a
cross-sectional view of FIG. 10. The rotating device 1100 includes
a rotating body that creates winds upon rotation. The rotating body
of the rotating device 1100 may include a hub 1138 fixed with an
impeller 1156. The impeller 1156 may include an annular part 1170
encircling the hub 1138 and fixed to the hub 1138, multiple
internal vanes 1172 extending outwardly in the radial direction
from the annular part 1170, and an external vane 1174 further
extending outwardly in the radial direction from an external end of
at least one internal vane 1172 in the radial direction. The
rotating device 1100 may have the stationary body with a thickness
of equal to or smaller than 3.2 mm in the direction of the rotation
axis R.
[0098] The rotating device 1100 of the seventh embodiment may
include the bearing mechanism of the rotating devices of the first
to sixth embodiments. In this case, according to the rotating
device 1100 of the seventh embodiment, the same advantageous
effects as those of the bearing mechanisms of the rotating devices
of the first to sixth embodiments can be accomplished.
[0099] The structures of the rotating devices according to the
embodiments and the operations thereof are explained above. Those
embodiments are merely examples, and it should be understood by
those skilled in the art that a combination of respective
structural components permits various modifications, and such
modifications are within the scope of the present disclosure.
[0100] In the first to fifth embodiments, the explanation was given
of an example case in which the number of salient poles of the
stator core 40 is nine, but the present disclosure is not limited
to this case. For example, the number of salient poles of the
stator core 40 maybe an integral multiple of 3 between 6 and 36.
This is merely an example, and the number of salient poles is not
limited to this range.
[0101] In the first to fifth embodiments, the explanation was given
of an example case in which the cylindrical magnet 32 is given with
12 driving polarities, but the present disclosure is not limited to
this case. For example, an even number of driving polarities
between 8 and 16 may be given to the cylindrical magnet 32. This is
merely an example, and the number of driving polarities is not
limited to this range.
[0102] In the fifth embodiment, the explanation was given of an
example case in which the inner circumference 424c of the retainer
member 424 is in a cylindrical shape, but the present disclosure is
not limited to this case. The inner circumference 424c can be
formed in various shapes. FIG. 9 is a cross-sectional view
illustrating a rotating device 700 according to a modified example.
FIG. 9 corresponds to FIG. 7. In this modified example, the inner
circumference 424c includes a tapered face decreasing the diameter
toward the bottom. When the rotating body stands still, the inner
circumference 424c and the side face 426b of the retained member
426 contact with each other.
* * * * *