Metal working – Method of mechanical manufacture – Electrical device making
Utility Patent
1996-01-03
2001-01-02
Hall, Carl E. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S606000, C029S609000, C310S049540, C310S256000
Utility Patent
active
06167610
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the construction of a thin structure motor for driving a medium used in a magnetic disk drive unit or an optical disk drive unit, the production method thereof, and the laminated core and the production method thereof.
2. Description of the Prior Art
FIG. 139
shows the stator of the spindle motor for the disk drive unit disclosed in Japanese Patent Publication No. 5-39020. The same Figure shows a stator core
20
formed integratedly by punching the magnetic material and stator coils
2
which are wound around respective teeth of the stator core
20
so that they are contained in respective slats. The spindle motor using this stator core
20
is called inner rotor type. Inside the stator, a rotor and rotor magnets are disposed so as to face the stator. The structure of the inner rotor makes it possible to form a thin structure motor and therefore is suitable for a magnetic disk drive unit and optical disk drive unit which are required to be of compact and thin structure.
FIGS. 140
,
141
show a stator of the spindle motor for the disk drive unit disclosed in Japanese Patent Laid-Open No. 2-133055 and the magnetic pole tooth of the stator core, respectively.
FIG. 140
shows the stator core formed integratedly by punching magnetic material and
FIG. 141
shows a magnetic tooth
15
of the stator core, which is wound with stator coil
2
. The spindle motor using this stator core is called outer rotor type. Outside the stator, a ring like rotor and rotor magnets are disposed so as to face the stator. A rotor shaft is located in the center of the stator and the rotor shaft is connected to the ring like rotor magnet through a thin circular plate. The spindle motor having such structure also makes it possible to obtain small diameter and thin structure, and therefore is often used as the spindle motor for driving a magnetic disk drive unit or an optical disk drive unit.
FIGS. 142A
,
142
B,
143
A,
143
B show part of the stator cores of other spindle motors for the disk drive unit disclosed in Japanese Patent Laid-Open No. 2-133055. The spindle motor using this stator core is also of outer rotor type. A difference thereof from the aforementioned outer rotor structure is that part of the respective magnetic teeth can be separated. In the stator core shown in
FIGS. 142A
,
142
B, slot heads
15
-
2
are inserted into the magnetic teeth wound with the coil
2
. In the stator core shown in
FIGS. 143A
,
143
B, respective magnetic teeth
15
-
3
wound with the coils
2
are inserted into the stator body
15
-
1
.
FIG. 146
shows the structure of a motor for the magnetic disk drive unit and optical disk drive unit disclosed in Japanese Utility Model Laid-Open No. 5-86151. This motor is of inner rotor type. As shown in the same Figure, three magnetic teeth constitute a stator core
20
as a single block. Each tooth
15
is wound with the coil
2
. The feature of this motor is that the stator core
20
is not disposed in the space in which the head of the disk drive unit moves. On the circumference of the rotor magnet
4
, in which the stator core
20
is not disposed, shield yokes
4
a
are disposed so as to cover the rotor magnet.
FIG. 147
is a partial sectional view showing the stator core and the coil of the spindle motor of conventional floppy disk drive unit disclosed in Japanese Patent Laid-Open No. 5-176484.
FIG. 148
is a front view of the spindle motor. This motor is of inner rotor type. In the respective Figures, reference numeral
122
designates a stator core formed by punching magnetic material integratedly and numeral
130
designates stator coil wound around the magnetic pole tooth
122
a
of the stator core
122
. The stator core
122
is formed by laminated core in which a plurality of magnetic materials are stacked. Resin layer is formed on the surface of the stator core
122
to insulate between the stator core
122
and the stator coil
130
. Reference numeral
112
designates a magnet, numeral
114
designates a shaft and numeral
116
designates a yoke.
FIG. 149
shows the stator core of a conventional thin structure motor disclosed in Japanese Patent Laid-Open No. 5-38109. As shown in the same Figure, insulating film
150
is formed on the circumference of the magnetic pole tooth of the stator core
151
. That is, the insulating sheet of thermoplastic resin is heated and pressed from both sides to form insulating film
150
on the circumference of the magnetic pole tooth in order to achieve insulation treatment.
The stator shown in
FIG. 139
has an integrated ring shaped stator core and therefore, it is difficult to wind the magnetic pole teeth facing inward of the stator with stator coil. In coiling, a nozzle through which wire is run is rotated around the magnetic pole teeth. However, because the inside of the stator core is small, the structure of the winding apparatus is complicated. Additionally, the coiling speed cannot be increased more than 1,000 rpm thereby suppressing the productivity of coiling low. It is impossible to increase the number of slots because the number of slots is restricted by the difficulty of coiling, thereby obstructing the increase of torque and resulting in torque ripple. Although winding wire of the coil neatly contributes to compacting and enhancement of the characteristic and reliability of the coil, it is impossible to wind wire neatly because the space between the stator core and the winding apparatus is very small.
FIG. 140
shows an integrated structure stator. Because the shape of the magnetic pole teeth of the stator core is complicated, it is impossible to wind wire effectively. For the reason, productivity is so low that cost increases and further a special winding apparatus is required.
Although the stator shown in
FIGS. 142A
,
142
B was proposed to solve the aforementioned problem, it is impossible to achieve effective winding of wire if the number of slots is increased to improve the characteristic of the motor. Further, magnetic resistance increases at portions in which divided stator portions are combined by engagement and air gap is unequalized, so that the characteristic of the motor deteriorates. Although winding procedure is facilitated to the stator shown in
FIG. 143
, two coil terminals are required for every magnetic pole tooth, thereby the step for connecting coil terminals electrically after coiling is required. Thus, production cost is increased and the reliability of connection is decreased.
By dividing the stator core into blocks in the motor shown in
FIG. 146
, the difficulty of coiling which is a problem of the inner rotor type is relaxed. However, the step for connecting the coils wound around the respective magnetic pole teeth in respective blocks after coiling is required, thereby increasing production cost and thus decreasing the reliability. Further, because the stator core is divided to blocks, it is difficult to fix the stator core with a certain gap with respect to the rotor magnet. Still further, because the stator core comprises divided blocks, the stator core is not easy to handle or assemble.
In the stators shown in
FIGS. 147 and 148
, the stator core
122
is of integrated ring structure. Therefore, it is difficult to wind the respective magnetic pole teeth
122
a
having small gap from an magnetic pole tooth nearby, with the stator coil
130
in the direction in which the stator coil is wound inward of the stator. Namely, when a nozzle through which wire is run is rotated around the magnetic pole tooth
122
a
for coiling, the structure of the winding apparatus is complicated because the inside of the stator core is small. Additionally, it is impossible to increase the winding speed over 1,000 rpm, thereby suppressing productivity low.
It is impossible to increase the number of slots because the number of slots is restricted by the difficulty of coiling, thereby obstructing the increase of torque and resulting in torque ripple. Although winding wire of the coil neatly contributes to compacting a
Akutsu Satoru
Azuma Ken-ichi
Fujita Youichi
Hasegawa Tadashi
Hashimoto Akira
Hall Carl E.
Mitsubishi Denki & Kabushiki Kaisha
Wolf Greenfield & Sacks P.C.
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