U.S. patent application number 09/895176 was filed with the patent office on 2002-04-25 for spindle motor and method of manufacturing the same.
This patent application is currently assigned to MINEBEA CO., LTD.. Invention is credited to Fukunaga, Kenji, Obara, Rikuro.
Application Number | 20020047393 09/895176 |
Document ID | / |
Family ID | 18715386 |
Filed Date | 2002-04-25 |
United States Patent
Application |
20020047393 |
Kind Code |
A1 |
Obara, Rikuro ; et
al. |
April 25, 2002 |
Spindle motor and method of manufacturing the same
Abstract
A spindle motor is formed so as to support a pivot of a rotor by
a pair of open bearings. The open bearings thus constructed will be
less expensive and simple structures, so that a manufacturing cost
thereof is reduced compared to a conventional spindle motor using a
pair of ball bearings with shields. Accordingly, a low-cost spindle
motor can be provided.
Inventors: |
Obara, Rikuro;
(Miyota-machi, JP) ; Fukunaga, Kenji;
(Miyota-machi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
MINEBEA CO., LTD.
Kitasaku-gun
JP
JP
|
Family ID: |
18715386 |
Appl. No.: |
09/895176 |
Filed: |
July 2, 2001 |
Current U.S.
Class: |
310/90 |
Current CPC
Class: |
F16C 19/06 20130101;
F16C 19/54 20130101; Y10T 29/49702 20150115; F16C 2235/00 20130101;
Y10T 29/49009 20150115; H02K 5/1735 20130101; F16C 33/6622
20130101; H02K 5/1737 20130101; Y10T 29/497 20150115; F16C 35/061
20130101 |
Class at
Publication: |
310/90 |
International
Class: |
H02K 005/16 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 21, 2000 |
JP |
2000-220854 |
Claims
What is claimed is:
1. A spindle motor for supporting a rotor by a pair of ball
bearings, wherein said pair of ball bearings is open ball bearings
of which both sides are open.
2. A spindle motor according to claim 1, wherein said pair of open
ball bearings is disposed in such a manner that extending parts
formed in one side of outer rings or inner rings abut each
other.
3. A spindle motor according to claim 1 or 2, wherein said pair of
open ball bearings is disposed in a shaft rotatable spindle motor
in which said inner rings rotate together with said rotor.
4. A spindle motor according to any one of claims 1 to 3, wherein
said pair of open ball bearings is disposed in a shaft fixed
spindle motor in which said outer rings rotate together with said
rotor.
5. A method of manufacturing a spindle motor for supporting a rotor
by a pair of ball bearings, said ball bearing being open ball
bearings both sides of which are opened, said method comprising: a
bearing washing process of cleaning said open ball bearings; a
grease filling process of filling grease in said open ball bearings
cleaned in said bearing washing process; and a bearing mounting
process of mounting said open ball bearings filled with the grease
in said grease filling process on said spindle motor; these
processes being sequentially performed upon assembly process of
said spindle motor.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a spindle motor and a
method of manufacturing thereof and more particularly to a spindle
motor for supporting a rotor using open ball bearings and a method
of manufacturing thereof.
[0003] 2. Description of the Related Art
[0004] FIG. 5 shows one example of a spindle motor 51 for driving a
hard disk drive device (hereinafter referred to as an HDD), more
specifically, a shaft fixed spindle motor 51 wherein a shaft 55 is
uprightly provided at the center of a base plate 54 and a rotor 53
is rotatably supported by interposing a pair of ball bearings 52
between the shaft 55 and the rotor 53. Further, FIG. 6 shows a
shaft rotatable spindle motor 61 for an HDD wherein a substantially
cylindrical fixed shaft 66 coaxial with a pivot 65 of a rotor 63 is
uprightly provided and the rotor 63 is made to be rotatable by
interposing a pair of ball bearings 52 between the fixed shaft 66
and the pivot 65 of the rotor 63. In general, the ball bearings 52
used for the spindle motors 51 and 61 are sealed ball bearings 52
both side surfaces of which are sealed by shields 56 so as to
prevent grease from spilling out and also prevent foreign materials
from entering as shown in FIGS. 5 and 6. Further, the shields 56
are arranged in grooves 52c consisted in both side surfaces of the
ball bearings 52 (outer rings 52a and inner rings 52b) so as to not
being protruded from the both side surfaces of the ball bearings
52. As shown in FIGS. 5 and 6, a pair of ball bearings 52 provided
in the spindle motors 51 and 61 are disposed at prescribed
intervals in the axial direction of the rotors 53 and 63 by
interposing annular spacers 57 therebetween.
[0005] In recent years price competitions for hardware is
intensified, and spindle motors for HDDs described above are not
exceptional thereto. However, in the above-described ball bearings
51 and 61, the grooves 52c at both side surfaces of the outer rings
52a and the inner rings 52b are needed to be machined so that not
only the cost of the ball bearings but also the one of the spindle
motors 51 and 61 are increased accordingly. Then, open bearings
without having shields 56 can be one of the choices because its
relative cost will be less expensive, but open bearings without
shields cannot be filled with grease in its assembly processes of
the ball bearings due to the requirement of controlling the amount
of grease as well as a pollution prevention before mounting into a
machine. Moreover, open bearings are difficult to be maintained
because foreign materials may enter the slide surfaces of the
bearings before assembling the machine, resulting in numbers of
difficulties when applying to the spindle motors 51 and 61.
SUMMARY OF THE INVENTION
[0006] Thus, the present invention is made in light of the above
problems and an object thereof is to reduce manufacturing cost as
well as to provide a spindle motor less expensive and a method of
manufacturing thereof.
[0007] For the object described above, according to a first aspect
of the present invention, there is provided a spindle motor for
supporting a rotor by a pair of ball bearings, wherein a pair of
ball bearings is open ball bearings of which both sides are
open.
[0008] The spindle motor thus constituted is less expensive than a
spindle motor using ball bearings with shields.
[0009] According to a second aspect of the present invention, there
is provided a spindle motor, wherein a pair of open ball bearings
is disposed in such a manner that extending parts formed in one
side of outer rings or inner rings abut each other.
[0010] By thus constructed, a spacer provided between a pair of
ball bearings will not be required, so that the manufacturing cost
of the spindle motor can be reduced.
[0011] According to a third aspect of the present invention, there
is provided a spindle motor, wherein a pair of open ball bearings
is disposed in a shaft rotatable spindle motor wherein the inner
rings rotate together with the rotor.
[0012] By thus constructed, the manufacturing cost of the spindle
motor can be reduced compared to a shaft rotatable spindle motor
using ball bearings with shields.
[0013] According to a fourth aspect of the present invention, there
is provided a spindle motor, wherein a pair of open ball bearings
is disposed in a shaft fixed spindle motor wherein the outer rings
rotate together with the rotor.
[0014] By thus constructed, the manufacturing cost of the spindle
motor can be reduced compared to a shaft fixed spindle motor using
ball bearings with shields.
[0015] According to a fifth aspect of the present invention, there
is provided a method of manufacturing a spindle motor for
supporting a rotor by a pair of ball bearings, open ball bearings
both sides of which are opened, the method comprising: a bearing
washing process of washing the open ball bearings; a grease filling
process of filling grease in the open ball bearings washed in the
bearing washing process; and a bearing mounting process of mounting
the open ball bearings filled with the grease in the grease filling
process on the spindle motor; these processes being sequentially
performed under a clean environment while assembling the spindle
motor.
[0016] By thus constructed, the open ball bearings can be mounted
on the spindle motor under a clean environment without foreign
materials, etc. and the manufacturing cost of the spindle motor can
be reduced compared to the spindle motor using the ball bearings
with the shields.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Other characteristics will be apparent in reference to the
attached drawings:
[0018] FIG. 1 is an explanatory view of a spindle motor according
to a first embodiment in which a pair of open bearings is disposed
in a shaft rotatable spindle motor;
[0019] FIG. 2 is an explanatory view of the spindle motor according
to the first embodiment in which a pair of open bearings is
disposed in a shaft rotatable spindle motor by interposing spacers
therebetween;
[0020] FIG. 3 is an explanatory view of a spindle motor according
to a second embodiment in which a pair of open bearings is disposed
in a shaft fixed spindle motor;
[0021] FIG. 4 is an explanatory view of the spindle motor according
to the second embodiment in which a pair of open bearings is
disposed in the shaft fixed spindle motor by interposing spacers
therebetween;
[0022] FIG. 5 is an explanatory view of a conventional spindle
motor in which a pair of ball bearings with shields is disposed in
a shaft fixed spindle motor;
[0023] FIG. 6 is an explanatory view of the conventional spindle
motor in which a pair of ball bearings with shields is disposed in
a shaft rotatable spindle motor; and
[0024] FIG. 7 is an explanatory view of a method of manufacturing
the spindle motor according to the first embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] A spindle motor according to a first embodiment of the
present invention and a method of manufacturing thereof will be
explained in reference to FIGS. 1 and 7. As shown in FIG. 1, a
pivot 5 of a rotor 3 is supported by using a pair of open bearings
2, so that the manufacturing cost of a spindle motor 1 can be
reduced compared to a conventional spindle motor 61 (see FIG. 6)
using ball bearings 52 with shields. Further, as FIG. 1 shows, an
extending part 8 formed by extending one side of each outer ring 6
is provided in a pair of open bearings 2 and the pair of open
bearings 2 are disposed in a shaft rotatable spindle motor 1 by
abutting the extending parts 8 each other. Thus, a spacer 57 (see
FIG. 6) interposed between a pair of ball bearings 52 is not needed
contrary to the conventional shaft rotatable spindle motor 61,
thereby the manufacturing cost of the shaft rotatable spindle motor
1 is reduced while an assembly work is simplified. And, as FIG. 7
shows in the spindle motor 1 according to the first embodiment, the
open bearings 2 can be mounted in the shaft rotatable spindle motor
1 by sequentially performing a bearing washing process 17, a grease
filling process 18 and a bearing mounting process 19 in an assembly
step of the spindle motor 1.
[0026] Now, the configuration of the spindle motor 1 will be
described in detail. As FIG. 1 shows, the spindle motor 1 can be
largely divided into a base member 4 and the rotor 3. The base
member 4 is provided with a substantially cylindrical fixed shaft 9
coaxial with the rotor 3 (pivot 5) and uprightly provided.
Moreover, the rotor 3 is provided with a hub 10 having an upright
side wall 10b at the side edge 10a of a disk part 10a, and the
pivot 5 is integrally formed with the hub 10. The spindle motor 1
according to the embodiment of the present invention is designed to
rotatably support the rotor 3 by interposing a pair of open
bearings 2 between the inner peripheral surface 9a of the fixed
shaft 9 of the base member 4 and the pivot 5 of the rotor 3. As
illustrated in FIG. 1, each pair of open bearings 2 has the
extending part 8 at one side of the outer ring 6 and since a pair
of open bearings 2 are disposed so as to abut their extending parts
8 each other, the spacer 57 (see FIG. 6) provided between a pair of
ball bearings 52 becomes not necessary. Accordingly, the
manufacturing cost of the spindle motor 1 can be reduced and the
bearing mounting work can be simplified.
[0027] Further, as shown in FIG. 1, a stator 11 including a stator
stack 11a and a coil 11b is fitted and fixed to the outer
peripheral surface 9b of the fixed shaft 9 on the base member 4. A
magnet 12 is disposed opposed to the stator 11 attached to the
fixed shaft 9 of the base member 4 on the inner peripheral surface
10c of the hub 10 of the rotor 3. And, on the fixed shaft 9 of the
base member 4, an annular shield member 14 is fitted and bonded to
the surface of a step part 13 formed in the upper part of an inner
peripheral surface 9a. In the spindle motor 1 according to the
embodiment of the present invention, a labyrinth seal structure is
formed at a small clearance between the inner diameter part of the
shield member 14 and the outer diameter of the boss part of the
pivot 5 and at a small clearance between the inner diameter part of
the annular protrusion part 10d of the hub 10 and the outer
peripheral surface 9b of the fixed shaft 9. Now, a method of
manufacturing the above-described spindle motor 1, particularly, a
method of mounting the open bearings 2 is hereinafter described
with reference to FIG. 7.
[0028] (1) Bearing Washing Process
[0029] In an assembly of the spindle motor 1 the open bearings 2
are assembled setting steel balls 20 between the outer rings 6 and
the inner rings 7 and then washed by a prescribed liquid through an
ultrasonic cleaning method, etc., for removing excess grease or
foreign materials remaining its surface.
[0030] (2) Grease Filling Process
[0031] And, the open bearings 2 washed in the bearing washing
process 17 are filled with grease having a prescribed property with
a grease filler device not shown.
[0032] (3) Bearing Mounting Process
[0033] Subsequently, the open bearings 2 filled with the grease in
the grease filling process 18 are pressed in in such a manner that
a pair of open bearings 2 are fixed to the inner peripheral surface
9a of the fixed shaft 9 of the base member 4 with the extending
parts 8 abutted each other. Then, after the shield member 14 is
attached to the step part 13 of the fixed shaft 9, the pivot 5 of
the rotor 3 is fitted, preloaded and attached to the inner rings 7
of the pair of open bearings 2 fixed by the fixed shaft 9 to form
the shaft rotatable spindle motor 1.
[0034] As described above, in the method of manufacturing the
spindle motor 1 according to the first embodiment of the present
invention, the bearing washing process 17, the grease filling
process 18 and the bearing mounting process 19 had better be
sequentially performed in a clean room when assembling the spindle
motor 1 whereby a pair of open bearings 2 can be mounted on the
shaft rotatable spindle motor 1 with few contamination.
[0035] Noted that spacers 57 may be interposed between a pair of
open bearings 2 as illustrated in FIG. 2 so as to form a shaft
rotatable spindle motor 21 with general-purpose open bearings
having no extending parts 8 in the outer rings 6.
[0036] Now, the spindle motor 1 according to the first embodiment
of the present invention will be described in its function. In the
spindle motor 1 of the present embodiment, the bearing washing
process 17, the grease filling process 18 and the bearing mounting
process 19 are sequentially performed when assembling the spindle
motor 1 whereby a pair of open bearings 2 can be mounted on the
shaft rotatable spindle motor 1 with few contamination. Therefore,
there can be provided the spindle motor 1 less expensive compared
to the conventional shaft rotatable spindle motor 61 (see FIG. 6)
provided with the ball bearings 52 with the shields.
[0037] Further, the extending part 8 formed by extending one side
of the outer ring 6 is provided in each of a pair of open bearings
2 and a pair of open bearings 2 is disposed in the spindle motor 1
with the extending parts 8 abutted each other. Accordingly, the
spacer 57 (see FIG. 6) interposed between a pair of ball bearings
52 becomes not necessary resulting in that the manufacturing cost
is reduced and the mounting work of the bearings is more
simplified.
[0038] Now, a spindle motor according to a second embodiment of the
present invention and a method of manufacturing thereof will be
described with reference to FIGS. 3 and 7. For the same parts as
those of the above-described spindle motor 1 and the method of
manufacturing thereof, the same names and numerals are employed.
First, the general structure of a spindle motor 31 according to a
second embodiment will be described. As shown in FIG. 3, the rotor
33 of the shaft fixed type spindle motor 31 is supported by a pair
of open bearings 2 whereby the manufacturing cost of the spindle
motor is reduced compared to a conventional shaft fixed spindle
motor 51 using a pair of ball bearings 52 with shields (see FIG.
5). Further, as shown in FIG. 3, an extending part 8 formed by
extending one side of each outer ring 6 is provided in a pair of
open bearings 2 and then the pair of open bearings 2 are disposed
in the shaft fixed type spindle motor 31 with the extending parts 8
abutted each other. Thus, a spacer 57 (see FIG. 6) interposed
between a pair of ball bearings 52 becomes not necessary so that
the manufacturing cost is reduced and an assembly work is more
simplified as compared to the conventional shaft fixed spindle
motor 51 (see FIG. 5). Further, as shown in FIG. 7, in the spindle
motor 31 in a second embodiment, the open bearings 2 can be mounted
on the shaft rotatable spindle motor 31 by sequentially performing
a bearing washing process 17, a grease filling process 18 and a
bearing mounting process 19 in the assembly process of the spindle
motor 31 similarly to the above described shaft rotatable spindle
motor 1.
[0039] Now, the configuration of the spindle motor 31 according to
the second embodiment will be described in detail. As shown in FIG.
3, the spindle motor 31 is largely divided into a base member 34
and the rotor 33. On the base member 34, a shaft 35 for supporting
the rotor 33 is uprightly provided. Further, the rotor 33 is
provided with a hub 36 having an upright side wall 36b on the side
edge of a disk part 36a. The disk part 36a is provided with a
cylindrical part 37 coaxial with the rotating shaft of the rotor
33. The spindle motor 31 according to the second embodiment is
designed to rotatably support the rotor 33 by interposing a pair of
open bearings 2 between the shaft 35 provided upright on the base
member 34 and the inner peripheral surface 37a of the cylindrical
part 37 of the rotor 33. As illustrated in FIG. 3, each of the pair
of open bearings 2 has the extending part 8 in one side of the
outer ring 6 and a pair of open bearings 2 are disposed with the
extending parts 8 abutted each other. Accordingly, the spacer 57
(see FIG. 5) interposed between a pair of ball bearings 52 becomes
not necessary, so that the manufacturing cost of the spindle motor
31 is reduced and the bearing mounting work is more simplified.
[0040] Further, as shown in FIG. 3, on the base member 34, an
annular wall 38 is uprightly provided coaxially with the shaft 35
and a stator 11 composed of a stator stack 11a and a coil 11b is
fitted and fixed to the outer peripheral surface 38a of the annular
wall 38. On the inner peripheral surface 36c of the hub 36 of the
rotor 33, a magnet 12 is provided opposed to the stator 11 attached
to the annular wall 38 of the base member 34. Further, as shown in
FIG. 3, a plate fitting hole 39 with a diameter larger than the
inner diameter of the cylindrical part 37 is formed aside at the
cylindrical part 37 provided in the hub 36. A substantially
disk-shaped plate 40 with a hole 40a through which the shaft 35
passes through in a very small clearance is fitted, bonded and
fixed to the plate fitting hole 39.
[0041] In a method of manufacturing the spindle motor 31 according
to the second embodiment, a pair of open bearings 2 can be mounted
on the shaft fixed spindle motor 31 in the same manner as the above
described shaft rotatable spindle motor 1 by sequentially
performing the bearing washing process 17, the grease filling
process 18 and the bearing mounting process 19 when assembling the
spindle motor 31.
[0042] Noted that a spacer 57 may be interposed between a pair of
open bearings 2 as illustrated in FIG. 4 so as to form a shaft
fixed spindle motor 41 with general-purpose open bearings 22 having
no extending parts 8 in the outer rings 6.
[0043] Now, the spindle motor 31 according to the second embodiment
of the present invention will be described in its function. In the
spindle motor 31 of the present embodiment, a bearing washing
process 17, a grease filling process 18 and a bearing mounting
process 19 are sequentially performed in the assembly process of
the spindle motor 31. Therefore, a pair of open bearings 2 can be
mounted on the shaft fixed spindle motor 31 with few contamination
whereby the manufacturing cost of the spindle motor 31 is reduced
compared to the conventional shaft fixed spindle motor 51 (see FIG.
5) provided with the ball bearings 52 with the shields.
[0044] Further, the extending part 8 formed by extending one side
of the outer ring 6 is provided in each of a pair of open bearings
2 and a pair of open bearings 2 are disposed in the spindle motor
31 with the extending parts 8 abutted each other. Therefore, the
spacer 57 (see FIG. 5) interposed between a pair of ball bearings
52 becomes not necessary whereby the manufacturing cost is reduced
and the mounting work of the bearings is more simplified.
[0045] According to the first aspect of the present invention,
since a rotor is supported with open bearings less expensive
compared to the conventional ball bearings with shields, the
manufacturing cost of the spindle motor is reduced.
[0046] According to the second aspect of the present invention,
since a pair of open bearings is disposed in a spindle motor in
such a manner that extending parts formed in one side of each outer
ring are abutted each other, a spacer interposed between a pair of
open bearings becomes not necessary whereby the manufacturing cost
of the spindle motor is reduced and the mounting work of the
bearings is more simplified.
[0047] According to the third aspect of the present invention,
since a pair of open bearings is disposed in a shaft rotatable
spindle motor, the manufacturing cost of a shaft rotatable spindle
motor is reduced compared to a spindle motor wherein a rotor is
supported by ball bearings with shields.
[0048] According to the fourth aspect of the present invention,
since a pair of open bearings is disposed in a shaft fixed spindle
motor, the manufacturing cost of the shaft fixed type spindle motor
is reduced compared to a spindle motor wherein a rotor is supported
by ball bearings with shields.
[0049] And, according to the fifth aspect of the present invention,
since a spindle motor is formed by sequentially performing a
bearing washing process, a grease filling process and a bearing
mounting process when being assembled, a pair of open ball bearings
can be mounted in the spindle motor; moreover, the spindle motor
can be formed less expensively compared to a spindle motor wherein
a rotor is supported by ball bearings with shields.
* * * * *