U.S. patent application number 12/320256 was filed with the patent office on 2009-06-18 for spindle motor.
This patent application is currently assigned to Panasonic Corporation. Invention is credited to Tsutomu Hamada, Katsuo Ishikawa.
Application Number | 20090152968 12/320256 |
Document ID | / |
Family ID | 36683156 |
Filed Date | 2009-06-18 |
United States Patent
Application |
20090152968 |
Kind Code |
A1 |
Ishikawa; Katsuo ; et
al. |
June 18, 2009 |
Spindle motor
Abstract
A spindle motor including a rotor hub which is rotationally
driven by a magnetic action of a rotational magnetic field
generated when a current is applied to a wire wound around teeth of
a stator core and a magnetic field of a magnet provided on a rotor.
Herein, the stator core formed by laminating magnetic steel plates
is mounted to an outer periphery of a supporting part of a rotation
support shaft of the rotor hub, and the supporting part is made of
sintered metal containing a ferromagnetic material. This spindle
motor can suppress generation of vibration and noise even when it
is reduced in size.
Inventors: |
Ishikawa; Katsuo; (Ozu-shi,
JP) ; Hamada; Tsutomu; (Hirakata-shi, JP) |
Correspondence
Address: |
STEPTOE & JOHNSON LLP
1330 CONNECTICUT AVE., NW
WASHINGTON
DC
20036
US
|
Assignee: |
Panasonic Corporation
Kadoma-shi
JP
|
Family ID: |
36683156 |
Appl. No.: |
12/320256 |
Filed: |
January 22, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11315310 |
Dec 23, 2005 |
|
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|
12320256 |
|
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Current U.S.
Class: |
310/90 |
Current CPC
Class: |
H02K 1/146 20130101;
H02K 1/02 20130101; H02K 5/00 20130101; H02K 5/1675 20130101 |
Class at
Publication: |
310/90 |
International
Class: |
H02K 5/167 20060101
H02K005/167 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2004 |
JP |
2004-375159 |
Claims
1. (canceled)
2. (canceled)
3. A spindle motor comprising: a stator comprising a stator core
having teeth; a wire wound around the teeth of the stator core; and
a rotor comprising a rotation support shaft, a rotor hubs and a
magnet, the rotor capable of being rotationally driven by a
magnetic action of a rotational magnetic field created when a
current is applied to the wire wherein a support part of the
rotation support shaft and the stator core are respectively made of
sintered metal containing a ferromagnetic material, and a
hydrodynamic bearing comprising an operating fluid between the
rotation support shaft and the supporting part, and at least a
portion of the supporting part of the rotation support shaft which
comes into contact with the operating fluid is pore-sealed.
4. (canceled)
5. (canceled)
6. (canceled)
7. The spindle motor according to claim 3, wherein the
ferromagnetic material comprises at least one of iron, nickel,
cobalt, and an alloy thereof.
8. The spindle motor according to claim 3, wherein the portion of
the supporting part of the rotation support shaft is impregnated
with a pore-sealing resin.
9. The spindle motor according to claim 8, wherein the portion of
the supporting part of the rotation support shaft is further
plated.
10. The spindle motor according to claim 3, comprising a shoulder
on a lower part of an outer periphery of the supporting part, and
the stator core is mounted on the shoulder of the supporting part.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a spindle motor for
rotationally driving a recording medium such as a magnetic disc or
an optical disc.
BACKGROUND OF THE INVENTION
[0002] As a spindle motor of this type, there have been known
spindle motors disclosed in JP-A 2004-248337, JP-A 2002-354742, and
the like.
[0003] In recent years, there have been successively developed AV
products and home electric products each of which includes a hard
disc drive. A use form of such products tends to be changed from a
stationary type to a portable type. From a request of portability,
there has been required a small-sized, thin spindle motor. In
addition, from a request of cost reduction, there has been also
required reduction in the number of components.
[0004] Particularly, in a spindle motor used in a hard disc drive,
a hydrodynamic bearing is adopted as a bearing for the purpose of
achieving high accuracy, silent performance, and extended service
life of the spindle motor.
[0005] Hereinafter, description will be given of a structure and
operation of a conventional spindle motor (see
JP-A2002-354742).
[0006] As illustrated in FIG. 7, a conventional spindle motor
includes a shaft 20, a flange 21, a sleeve 22, a thrust plate 23,
an adhesive 24, a rotor hub 25, a magnet 26, a stator core 27, a
coil 28, a base internal cylindrical part 29, an attraction plate
30, and a base member 31.
[0007] First, the flange 21 is fixed to the shaft 20 by means of
laser welding or the like. Next, the shaft 20 is inserted into and
fitted to the sleeve 22. Thereafter, the thrust plate 23 is brought
into contact with the flange 21, and a tip end 32 of the sleeve 22
is fixed to the thrust plate 23 by means of caulking or the like.
Further, the thrust plate 23 is sealed with the adhesive 24. Thus,
a bearing unit is assembled. Then, the bearing unit is filled with
lubricating fluid (not illustrated), so that a hydrodynamic bearing
is obtained. The rotor hub 25 to which the magnet 26 is fixedly
bonded by an adhesive or the like is fixed to the bearing unit
assembled as described above; thus, a rotor unit is obtained.
[0008] On the other hand, the attraction plate 30 is fixedly bonded
to the base member 31 by an adhesive or the like. The stator core
27 having the coil 28 wound therearound is fixedly bonded to the
base internal cylindrical part 29; thus, a stator unit is obtained.
Finally, the rotor unit is fitted to the stator unit and, then,
they are fixedly bonded to each other by an adhesive or the like.
In the spindle motor configured as described above, when a current
is applied to the coil 28 such that a rotational magnetic field is
generated at an outer periphery of the stator core 27, the rotor
unit starts to rotating. Then, a radial bearing is formed by
dynamic pressure generating grooves cut on an outer periphery of
the shaft 20 or an inner circumference of the sleeve 22, a thrust
main bearing is formed by dynamic pressure generating grooves cut
on a lower face of the flange 21 or an upper face of the thrust
plate 23, and a thrust sub bearing is formed by dynamic pressure
generating grooves cut on an upper face of the flange 21 or a lower
face of the sleeve 22. Thus, the rotor unit rotates with respect to
the stator unit in a non-contact manner. The magnet 26 generates an
attraction force in relation to the attraction plate 30; therefore,
a displacement of the rotor unit in an axial direction is not
largely changed by a posture of the spindle motor.
[0009] JP-A 2004-248337 discloses a spindle motor wherein a stator
core is directly fitted to a sleeve for the purpose of
downsizing.
[0010] However, even when the size of the spindle motor having the
aforementioned conventional configuration is simply reduced, a
required torque cannot be attained. In addition, a dimension of the
magnet is made relatively large and the number of windings of the
coil is increased. Consequently, magnetic saturation occurs in the
stator core, a torque waveform is distorted, and vibration and
noise are generated. As a result, it is impossible to sufficiently
reduce the size of the spindle motor under present
circumstances.
SUMMARY OF THE INVENTION
[0011] It is an object of the present invention to provide a
spindle motor which can suppress generation of vibration and noise
even when a size thereof is reduced. Further, the number of
assembling processes can be reduced, achieving low cost
manufacturing.
[0012] According to a first aspect of the present invention, a
spindle motor is comprised of a stator including a stator core
having teeth, and a rotor including a rotation support shaft, a
rotor hub and a magnet, the rotor being rotationally driven by a
magnetic action of a rotational magnetic field occurring when a
current is applied to a wire wound around the teeth of the stator
core and a magnetic field of the magnet of the rotor, wherein the
stator core formed by laminating magnetic steel plates is mounted
to an outer periphery of a supporting part (a portion corresponding
to a sleeve) of the rotation support shaft of the rotor, and the
supporting part of the rotation support shaft is made of sintered
metal containing a ferromagnetic material.
[0013] According to this configuration, the supporting part (a
portion corresponding to a sleeve) of the rotation support shaft of
the rotor is made of sintered metal containing a ferromagnetic
material. Therefore, even when a size of the stator core is reduced
so that a width of a teeth yoke for connecting base ends of the
teeth becomes narrower, magnet flux of the teeth effectively passes
through the supporting part made of sintered metal containing a
ferromagnetic material. Thus, it is possible to decrease magnetic
saturation in the stator core and to suppress generation of
vibration and noise with reliability.
[0014] According to a second aspect of the present invention, a
spindle motor is comprised of a stator including a stator core
having teeth, and a rotor including a rotation support shaft, a
rotor hub and a magnet, the rotor being rotationally driven by a
magnetic action of a rotational magnetic field occurring when a
current is applied to a wire wound around the teeth of the stator
core and a magnetic field of the magnet of the rotor, wherein a
supporting part of the rotation support shaft of the rotor, and the
teeth formed on an outer periphery of the supporting part and wound
therearound with the wire are integrally formed using sintered
metal containing a ferromagnetic material. According to this
configuration, it is possible to further decrease magnetic
saturation in the stator core and to suppress generation of
vibration and noise with reliability.
[0015] According to a third aspect of the present invention, a
spindle motor is comprised of a stator including a stator core
having teeth, and a rotor including a rotation support shaft, a
rotor hub and a magnet, the rotor being rotationally driven by a
magnetic action of a rotational magnetic field occurring when a
current is applied to a wire wound around the teeth of the stator
core and a magnetic field of the magnet of the rotor, wherein a
supporting part of the rotation support shaft and the stator core
are respectively made of sintered metal containing a ferromagnetic
material, and the stator core is mounted to an outer periphery of
the supporting part. According to this configuration, even when the
spindle motor is reduced in size, productivity thereof is good.
[0016] According to a fourth aspect of the present invention, a
spindle motor is comprised of a stator including a stator core
having teeth, and a rotor including a rotation support shaft, a
rotor hub and a magnet, the rotor being rotationally driven by a
magnetic action of a rotational magnetic field occurring when a
current is applied to a wire wound around the teeth of the stator
core and a magnetic field of the magnet of the rotor, wherein a
supporting part of the rotation support shaft, and an attraction
part formed on a base end part of the supporting part and extending
in the vicinity of the magnet so that the magnet receives an
attraction force therefrom, are integrally formed using sintered
metal containing a ferromagnetic material, and the stator core
formed by laminating magnetic steel plates is mounted to an outer
periphery of the supporting part of the rotation support shaft.
According to this configuration, it is possible to further reduce
the number of components.
[0017] According to a fifth aspect of the present invention, a
spindle motor is comprised of a stator including a stator core
having teeth, and a rotor including a rotation support shaft, a
rotor hub and a magnet, the rotor being rotationally driven by a
magnetic action of a rotational magnetic field occurring when a
current is applied to a wire wound around the teeth of the stator
core and a magnetic field of the magnet of the rotor, wherein a
supporting part of the rotation support shaft, the teeth formed on
an outer periphery of the supporting part and wound therearound
with the wire, and an attraction part formed on a base end part of
the supporting part and extending in the vicinity of the magnet so
that the magnet receives an attraction force therefrom, are
integrally formed using sintered metal containing a ferromagnetic
material. According to this configuration, it is possible to
further reduce the number of components.
[0018] According to a sixth aspect of the present invention, a
spindle motor is comprised of a stator including a stator core
having teeth, and a rotor including a rotation support shaft, a
rotor hub and a magnet, the rotor being rotationally driven by a
magnetic action of a rotational magnetic field occurring when a
current is applied to a wire wound around the teeth of the stator
core and a magnetic field of the magnet of the rotor, wherein a
supporting part of the rotation support shaft, and an attraction
part formed on a base end part of the supporting part and extending
in the vicinity of the magnet so that the magnet receives an
attraction force therefrom, are integrally formed using sintered
metal containing a ferromagnetic material, and the stator core made
of sintered metal containing a ferromagnetic material is mounted to
an outer periphery of the supporting part of the rotation support
shaft. According to this configuration, it is possible to reduce
the number of components, to improve productivity of a spindle
motor when a size thereof is reduced, to decrease magnetic
saturation in a stator core, and the like.
[0019] According to a seventh aspect of the present invention, in
the spindle motor according to any one of the first to sixth
aspects, the ferromagnetic material contained in the sintered metal
includes at least one of iron, nickel, cobalt, and an alloy
thereof.
[0020] According to an eighth aspect of the present invention, in
the spindle motor according to any one of the first to sixth
aspects, the supporting part of the rotation support shaft made of
the sintered metal is subjected to pore sealing treatment by being
impregnated with resin, in at least a portion thereof which may
come into contact with operating fluid.
[0021] According to a ninth aspect of the present invention, in the
spindle motor according to any one of the first to sixth aspects,
the supporting part of the rotation support shaft made of the
sintered metal is subjected to pore sealing treatment by being
impregnated with resin and further to plating treatment, in at
least a portion thereof which may come into contact with operating
fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1A is a sectional view of a spindle motor according to
a first embodiment of the present invention;
[0023] FIG. 1B is a sectional view of a main portion of the spindle
motor, taken along line A-A' of FIG. 1A;
[0024] FIG. 2A is a sectional view of a spindle motor according to
a second embodiment of the present invention;
[0025] FIG. 2B is a sectional view of a main portion of the spindle
motor, taken along line A-A' of FIG. 2A;
[0026] FIG. 3A is a sectional view of a spindle motor according to
a third embodiment of the present invention;
[0027] FIG. 3B is an assembly view of a main portion of the spindle
motor;
[0028] FIG. 4A is a sectional view of a spindle motor according to
a fourth embodiment of the present invention;
[0029] FIG. 4B is an assembly view of a main portion of the spindle
motor;
[0030] FIG. 5A is a sectional view of a spindle motor according to
a fifth embodiment of the present invention;
[0031] FIG. 5B is a sectional view of a main portion of the spindle
motor, taken along line A-A' of FIG. 5A;
[0032] FIG. 6A is a sectional view of a spindle motor according to
a sixth embodiment of the present invention;
[0033] FIG. 6B is an assembly view of a main portion of the spindle
motor; and
[0034] FIG. 7 is a sectional view of a conventional spindle
motor.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0035] Hereinafter, description will be given of embodiments of the
present invention with reference to the drawings.
First Embodiment
[0036] FIGS. 1A and 1B illustrate a first embodiment of the present
invention.
[0037] It is to be noted that FIG. 1B illustrates a state where a
wire 13 is not wound around teeth 12.
[0038] As illustrated in FIG. 1A, a shaft 2 is rotatably inserted
into a bearing hole 1a of a sleeve 1. A radial bearing face having
dynamic pressure generating grooves 3A and 3B formed as patterned
shallow grooves is provided on at least one of an outer peripheral
face of the shaft 2 and an inner circumferential face of the sleeve
1. A rotor hub 5 having a magnet 4 at an inner circumference of its
thick-diameter portion is attached to an upper portion of the shaft
2. A thrust flange 6 is integrally attached to the other end (a
lower portion in FIG. 1A) of the shaft 2 so as to be perpendicular
to the shaft 2.
[0039] A bearing face on a lower end side of the thrust flange 6
opposes a thrust plate 7, and the thrust plate 7 is fixed to the
sleeve 1. Spiral-shaped or herringbone-patterned dynamic pressure
generating grooves 8A are cut on at least one of the faces of the
thrust flange 6 and the thrust plate 7. Herein, the faces of the
thrust flange 6 and the thrust plate 7 oppose each other. Dynamic
pressure generating grooves 8B are formed on at least one of faces
of an upper flat face portion of the thrust flange 6 and the sleeve
1. Herein, the faces of the upper flat face portion of the thrust
flange 6 and the sleeve 1 oppose each other. A base end of the
sleeve 1 is fixed to a base 10. In this embodiment, the base 10 is
formed by aluminum die-casting. An attraction part 16 is fixedly
bonded to the base 10.
[0040] A stator core 9 formed by laminating magnetic steel plates
is finished to have a shape that base ends of teeth 12 having a
wire 13 wound therearound are coupled to one another by a yoke 14
(see FIG. 1B). This stator core 9 is press-fitted or adhered to an
outer peripheral face of the sleeve 1. An inner circumferential
face 15 of the yoke 14 of the stator core 9 is in direct contact
with the outer peripheral face of the sleeve 1 without
clearance.
[0041] Further, a clearance between the shaft 2 and the sleeve 1
and a clearance between the thrust flange 6 and the thrust plate 7
are filled with oil 11 serving as operating fluid.
[0042] Herein, the sleeve 1 is made of sintered metal containing a
ferromagnetic material. Specific examples of the ferromagnetic
material include iron, nickel, cobalt and the like and an alloy
thereof. In the case of using sintered metal containing iron, a raw
material powder of almost 100% pure iron is evenly mixed,
press-molded, and sintered. Further, the resultant is subjected to
pore sealing treatment. In the pore sealing treatment, the
resultant is impregnated with resin and, if necessary, is coated
with plating after impregnation with resin. In addition, dynamic
pressure generating grooves are cut on the bearing hole 1a or the
like by means of ball rolling or the like. Herein, a portion in the
vicinity of the teeth 12 of the stator core 9 is subjected to
insulating treatment and, then, the wire 13 is wound around the
teeth 12 of the stator core 9.
[0043] Herein, the pore sealing treatment refers to treatment in
which pores are closed to prevent the following factor. That is,
operating fluid oozes from minute voids remaining after sintering
of the sintered metal, so that a fluid amount and a fluid pressure
decrease.
[0044] A conventional sleeve 4 disclosed in JP-A 2004-248337 is
made of stainless steel and is manufactured by cutting processing.
As compared with such a sleeve 4, the sleeve made of sintered metal
containing a raw material powder of 100% pure metal has the
following excellent magnetic characteristics. That is, magnetic
resistance is low, magnetic saturation is also low, and magnetic
flux favorably passes therethrough.
[0045] This spindle motor operates as follows.
[0046] First, when a current is applied to the wire 13, a
rotational magnetic field is generated from the stator core 9.
Then, the rotor hub 5 and the shaft 2 are rotationally driven by a
magnetic action of the rotational magnetic field of the stator core
9 and a magnetic field of the magnet 4 on the rotor side. Herein,
the rotor hub 5 rotates at an appropriate position where a biasing
force by attraction of the magnet 4 toward the attraction part 16
serving as an attraction part having an outer periphery extending
to a portion in the vicinity of the magnet 4 is proportional to a
floating force by the thrust flange 6.
[0047] When the rotor hub 5 and the shaft 2 start rotating, a
pumping pressure is generated in the oil 11 by the dynamic pressure
generating grooves 3A, 3B, 8A and 8B, and a pressure in bearing
parts (a radial bearing part and a thrust bearing part) becomes
high. Thus, the shaft 2 and the thrust flange 6 float with respect
to the sleeve 1 and the thrust plate 7, and rotate with high
accuracy in a non-contact manner. More specifically, a radial
bearing which rotatably supports in a state of having a
predetermined clearance in a radial direction is formed at a
portion of the dynamic pressure generating grooves 3A and 3B, and a
thrust bearing which rotatably supports in a state of having a
predetermined clearance in a thrust direction is formed at a
portion of the dynamic pressure generating grooves 8A and 8B.
[0048] Although not illustrated in the drawings, one or plural
disc(s) as a magnetic recording medium can be fixed to the rotor
hub 5. The rotor hub 5 rotates together with the disc(s) to
record/reproduce an electric signal.
[0049] In this configuration, even when the size of the spindle
motor is reduced and a width W of the yoke 14 becomes narrower,
magnetic flux .phi. passes through not only the yoke 14 but also
the sleeve 1 made of sintered metal containing a ferromagnetic
material, as shown by an imaginary line in FIG. 1B. It is therefore
possible to prevent magnetic resistance from increasing.
[0050] Accordingly, it is possible to decrease the magnetic
saturation in the stator core 9 and to suppress generation of
vibration and noise with reliability.
Second Embodiment
[0051] FIGS. 2A and 2B illustrate a second embodiment of the
present invention.
[0052] In the first embodiment illustrated in FIGS. 1A and 1B, the
stator core 9 is formed by laminating magnetic steel plates, and
the sleeve 1 is made of sintered metal containing a ferromagnetic
material. In the second embodiment illustrated in FIGS. 2A and 2B,
the stator core 9 is also made of sintered metal containing a
ferromagnetic material and is integrally formed with the sleeve 1.
The second embodiment is different from the first embodiment in
only this point.
[0053] According to this configuration, magnetic flux .phi. which
has passed through the teeth 12 of the stator core 9 passes through
the sleeve 1 made of sintered metal containing a ferromagnetic
material; therefore, it is possible to prevent magnetic resistance
from increasing. Accordingly, it is possible to decrease magnetic
saturation in the stator core 9 and to suppress generation of
vibration and noise with reliability.
Third Embodiment
[0054] FIGS. 3A and 3B illustrate a third embodiment of the present
invention.
[0055] In the second embodiment illustrated in FIGS. 2A and 2B, the
sleeve 1 and the stator core 9 are integrally formed with each
other using sintered metal containing a ferromagnetic material. In
the third embodiment, as illustrated in FIG. 3A, the sleeve 1 and
the stator core 9 are separately provided, and are respectively
made of sintered metal containing a ferromagnetic material.
[0056] According to this configuration, the wire 13 is wound around
the stator core 9 made of sintered metal containing a ferromagnetic
material and, then, the stator core 9 is mounted to the outer
periphery of the sleeve 1 as illustrated in FIG. 3B. The third
embodiment is different from the second embodiment in only this
point. The sleeve 1 is subjected to pore sealing treatment such as
impregnation with resin before assembly with the stator core 9 and,
further, dynamic pressure generating grooves are formed on the
bearing hole 1a, like the first embodiment.
[0057] With this configuration, the pore sealing treatment and the
dynamic pressure generating groove forming process in the sleeve 1
as well as the process for winding the wire 13 around the stator
core 9 can be simultaneously carried out in parallel.
Fourth Embodiment
[0058] FIGS. 4A and 4B illustrate a fourth embodiment of the
present invention.
[0059] In the first embodiment illustrated in FIGS. 1A and 1B, the
sleeve 1 is attached to the base 10, and the attraction part 16 is
fixedly bonded to the base 10. In the fourth embodiment, as
illustrated in FIG. 4A, the sleeve 1 and the attraction part
extending to a portion in the vicinity of the magnet 4 are
integrally formed with each other using sintered metal containing a
ferromagnetic material. The fourth embodiment is different from the
first embodiment in only this point.
[0060] According to this configuration, a process for attaching the
attraction part 16, which is necessary in the first embodiment, can
be eliminated. As illustrated in FIG. 4B, the wire 13 is wound
around the stator core 9 and, then, the stator core 9 is mounted to
the outer periphery of the sleeve 1. The base 10 is fixedly bonded
to a portion in the vicinity of the attraction part 16 integrally
formed with the sleeve 1.
Fifth Embodiment
[0061] FIGS. 5A and 5B illustrate a fifth embodiment of the present
invention.
[0062] In the fourth embodiment illustrated in FIGS. 4A and 4B, the
stator core 9 is formed by laminating magnetic steel plates. In the
fifth embodiment, as illustrated in FIG. 5A, the sleeve 1, the
attraction part 16, and the teeth 12 corresponding to the stator
core 9 are integrally formed with one another using sintered metal
containing a ferromagnetic material. The fifth embodiment is
different from the fourth embodiment in only this point.
[0063] According to this configuration, a process for attaching the
attraction part 16, which is necessary in the first embodiment, can
be eliminated. Further, a process for assembling the stator core 9
and the sleeve 1 can be also eliminated.
Sixth Embodiment
[0064] FIGS. 6A and 6B illustrate a sixth embodiment of the present
invention.
[0065] In the fifth embodiment illustrated in FIGS. 5A and 5B, the
sleeve 1, the attraction part 16, and the teeth 12 corresponding to
the stator core 9 are integrally formed with one another using
sintered metal containing a ferromagnetic material. In the sixth
embodiment, as illustrated in FIG. 6A, the sleeve 1 and the
attraction part 16 are integrally formed with each other using
sintered metal containing a ferromagnetic material; however, the
stator core 9 is separated from the sleeve 1 and is made of
sintered metal containing a ferromagnetic material. The sixth
embodiment is different from the fifth embodiment in only this
point. Like the first embodiment, the sleeve 1 is subjected to pore
sealing treatment such as impregnation with resin prior to assembly
with the stator core 9 and, further, dynamic pressure generating
grooves are formed on the bearing hole 1a and the like.
[0066] According to this configuration, the wire 13 is wound around
the stator core 9 made of sintered metal containing a ferromagnetic
material and, then, the stator core 9 can be mounted to the outer
periphery of the sleeve 1, as illustrated in FIG. 6B. Thus, the
pore sealing treatment and the dynamic pressure generating groove
forming process in the sleeve 1 as well as the process for winding
the wire 13 around the stator core 9 can be simultaneously carried
out in parallel.
[0067] In the aforementioned embodiments, description is given of
the base 10 made of a non-magnetic aluminum die-cast material or
the like. However, the first to third embodiments are effective
even when the base member is formed by a presswork and the like
using an iron-based material or the like which is a magnetic
material. In this case, since the base member functions as an
attraction part, the attraction part 16 can be eliminated.
[0068] In the aforementioned embodiments, when the ferromagnetic
material contained in the sintered metal includes at least one of
iron, nickel, cobalt, and an alloy thereof, the similar effects can
be expected.
[0069] In the aforementioned embodiments, when the supporting part
of the rotation support shaft made of the sintered metal is
subjected to pore sealing treatment of impregnation with resin in
at least a portion with which operating fluid may be brought into
contact, the similar effects can be expected.
[0070] In the aforementioned embodiments, when the supporting part
of the rotation support shaft made of the sintered metal is
subjected to pore sealing treatment of impregnation with resin and,
further, plating treatment in at least a portion with which
operating fluid may be brought into contact, the similar effects
can be expected.
[0071] In the aforementioned embodiments, examples of the operating
fluid may include, in addition to oil, grease with high fluidity,
and ionic liquid.
[0072] The present invention can contribute to suppression of
generation of vibration and noise caused by downsizing of a spindle
motor, to reduction of the number of assembling processes and cost
by reduction of the number of components, and to achievement of
downsizing and cost reduction of AV products, home electric
products and the like each of which uses a spindle motor for
rotationally driving a recording medium.
* * * * *