Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2002-02-14
2004-03-30
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S185000, C310S158000, C310S156350
Reexamination Certificate
active
06713926
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to technology suitably used for a thin inner rotor motor for medium rotation driving used in, e.g., a floppy disk drive and the like.
2. Description of the Prior Art
Disk units such as floppy disk drives are in wide use with personal computers, office computers, and word processors, and are becoming remarkably widespread. This type of disk unit is constructed as shown in FIG.
10
.
This type of disk unit is described briefly with reference to the drawing. In the drawing, the reference numeral
101
designates a chassis having a spindle center
102
as a disk rotation center thereof, which is housed in an equipment housing (not shown) of, e.g., personal computer, and is formed by a closed-end box that is open in forward and upward directions as a whole and has a housing space for housing a disk cartridge
103
.
In a rearward portion of the chassis
101
are provided a stepping motor
124
for feeding a head carriage and the head carriage shuttled back and forth by the stepping motor
124
. At the tip of the head carriage is held a first head
130
for reading recorded information from disk, and at a backward, upper portion of the head carriage is provided a head arm
132
having a second head
131
corresponding to the first head
130
, the head arm
132
being swingably mounted through an elastic member. The head arm
132
is energized in a direction in which the second head
131
approaches the first head
130
. The disk unit of this example is provided with a cartridge holder
136
for holding the disk cartridge
103
that can be freely inserted or removed, and a mechanism for opening and closing a shutter of the disk cartridge
103
.
This type of disk unit is equipped with an inner rotor motor as shown in
FIGS. 11A and 11B
as a motor for rotating disk to meet recent demands for thinner disk units.
This comprises: an annular yoke
161
extending in a circumferential direction; a stator
164
having a large number of cores
163
, provided radially in the inner circumference of the yoke
161
, around each of which a coil
162
is wound; and a rotor
166
having an annular magnet
165
that is rotatably provided in the inner circumference of the stator
164
and faces the cores
163
. The reference numeral
168
in the drawing designates a circuit board on which a holding part
170
incorporating a bearing
169
is mounted, and
171
designates a rotation axis for securing the rotor that is rotatably supported to the holding part
170
on the circuit board through the bearing
169
and extends vertically. The rotor
166
of the inner rotor motor functions as a turn table having a disk chucking magnet (not shown) and a disk chucking rotation lever (not shown).
In the inner rotor motor stator of this type, the yoke
161
and the cores
163
are provided to surround the almost entire circumference of the circular rotor
166
except the movement position of the heads
130
and
131
. To satisfy the magnetic properties and other requirements, more expensive silicon steel plate than a galvanized steel plate is used to form the chassis
101
and other components.
However, for this type of disk unit, there have been a continued demand to reduce its manufacturing costs and a persistent demand to reduce the unit in size and weight.
For this reason, the inventor believes that there has been in an inner rotor motor stator a demand to reduce the space of the yoke
161
and the cores
163
that are made of expensive silicon iron.
However, if the space of the yoke
161
and the cores
163
is reduced to satisfy the above-described demand, magnetic interaction with the rotor
166
might become uneven in the circumferential direction and disk operation might become unstable.
Also, to reduce the space of the cores
163
, the stator might be partitioned to have three cores. In this case, since the cores are often provided in parallel to each other, the interval between the tips of the cores would become too narrow, causing the problem that coils could not be wound.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above circumstances and intends to achieve the following objects:
(a) reducing manufacturing costs;
(b) reducing the unit in size and weight;
(c) keeping motor rotation stable;
(d) increasing the operation stability of the disk unit; and
(e) pushing forward with reduction in stator size.
The above-described problems have been solved by an inner rotor motor of the present invention comprising: a rotor having plural magnetic poles disposed in a circumferential shape; and a stator including a stator core having plural magnetic pole teeth that are outside a circumference of the rotor and face the rotor, a coil being wound around each of the magnetic pole teeth, wherein the magnetic pole teeth are set so that the value of at least one of angles each formed by extensions of adjacent magnetic pole teeth is smaller than an angle formed by lines each connecting a tip center of one of adjacent magnetic pole teeth and a rotation center of the rotor.
In the present invention, the magnetic pole teeth may also be provided so that at least one of points of intersection of extensions of lines each connecting a base center and a tip center of one of adjacent magnetic pole teeth is in a position opposite to the magnetic pole teeth with respect to the rotation center of the rotor.
The magnetic pole teeth of the present invention can be placed so that extensions of lines each connecting a base center and a tip center thereof intersect at an identical point.
In the present invention, it is desirable that the magnetic pole teeth are provided so that intervals between the base centers of adjacent magnetic pole teeth are equal to each other.
Base centers of the magnetic pole teeth can be provided to be at an equal distance from a point opposite to the magnetic pole teeth with respect to the rotation center of the rotor.
In the present invention, it is desirable that the magnetic pole teeth are provided so that a value of at least one of angles each formed by extensions of adjacent magnetic pole teeth is 15 degrees or less.
It is desirable that the stator of the present invention is provided so that a central angle of the rotor with respect to the stator is in a range within 180 degrees.
Furthermore, it is desirable that six of the magnetic pole teeth are provided.
The disk unit of the present invention may include the above-described inner rotor motor.
In the present invention, the magnetic pole teeth are set so that the value of at least one of angles each formed by extensions of adjacent magnetic pole teeth is smaller than an angle formed by lines each connecting the tip center (tip center position) of one of adjacent magnetic pole teeth and the rotation center of the rotor. With this construction, in comparison with the case where magnetic pole teeth are provided radially from the rotor center as shown in
FIG. 11
, the interval between the adjacent magnetic pole teeth is reduced, and the space of yoke to which the magnetic pole teeth are connected is reduced, especially miniaturizing the stator and contributing to reduction in manufacturing costs.
The magnetic pole teeth are provided so that at least one of points of intersection of extensions of lines each connecting the base center and tip center of one of adjacent magnetic pole teeth is in a position opposite to the magnetic pole teeth with respect to the rotation center of the rotor. With this construction, it can be prevented that coils cannot be wound because of too small an interval between adjacent magnetic pole teeth.
Herein, the base center refers to the central position of a portion to which a magnetic pole tooth is connected to the yoke, in the circumferential direction of the rotor, and the tip center refers to the central position of a magnetic pole teeth face (rotor facing face) opposite to the rotor in the circumferential direction of the rotor.
The magnetic pole teeth of the present invention are placed so that extensions of lin
Alps Electric Co. ,Ltd.
Mohandesi Iraj A.
Nguyen Tran
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