JP2605953B2 - Electric motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor, and in particular, to recording used in an apparatus having a magnetic head for reading and writing magnetic recording signals of a magnetic disk which is a disk-shaped recording medium. The present invention relates to an electric motor for rotating a medium.

[Prior Art] As a conventional electric motor of this type, there is a technique disclosed in Japanese Utility Model Laid-Open No. 60-13563.

 FIG. 5 is a sectional view showing a conventional electric motor.

In the figure, reference numeral 1 denotes a rotating shaft of a motor, and 2 denotes a rotating body having a magnetic disk holding function. The rotating body 2 rotates integrally with the rotating shaft 1. 3 is an electric motor rotor,
Reference numeral 4 denotes a yoke of the rotor 3, reference numeral 5 denotes a permanent magnet disposed on an outer peripheral portion of the yoke 4, reference numeral 6 denotes a screw fixing the rotor 3 and the rotating shaft 1, reference numeral 7 denotes a stator of the electric motor, and reference numeral 8 Is a core of the stator 7, 9 is a coil wound around the iron core 8, 10 is a bearing mounting member, and 11 and 12 are bearings mounted on the bearing mounting member 10 and rotatably supporting the rotary shaft 1. 13 is the motor frame,
14 is a screw fixing the stator 7 and the bearing mounting member 10,
Reference numeral 15 denotes a drive pin mounted on the rotating body 2, and the drive pin 15 is engaged with a window hole (not shown) of a rotating plate fixed to the magnetic disk. Reference numeral 16 denotes an index detecting element provided on the frame 13, and 17 denotes an index detecting magnet provided on the rotor 3. The index detecting element 16 and the index detecting magnet 17 generate one pulse per rotation. I do.

The electric motor having the above configuration is of a so-called outer rotor type in which the rotor 3 is located outside the stator 7, and the permanent magnets 5 of the rotor 3 generate a magnetic field in the radial direction of rotation. In this electric motor, the rotor 3 is rotationally driven by controlling the energization of the coil 9 wound around the iron core 8 of the stator 7 by a predetermined element (not shown). The rotation of the rotor 3 drives the magnetic disk (not shown) to rotate appropriately.

[Problems to be Solved by the Invention] In the conventional outer rotor type electric motor as described above,
Some space was required between the rotor 3 and the stator 7. Further, the frame 13 or the bearing mounting member 10 is interposed between the stator 7 and the rotor 3 and the magnetic disk and the magnetic head. Therefore, there is a limit in reducing the thickness of the electric motor. For this reason, the stator 7 is provided outside the rotor 3.
Has been considered to be a thin inner rotor type electric motor in which is located. However, in this type of electric motor as well, there is a possibility that the stator core of the stator and the magnetic head may interfere with each other, so that a predetermined gap is required on the magnetic disk side of the stator to avoid interference with the magnetic head. And had For this reason, the thickness of the whole electric motor could not be made very thin.

On the other hand, as another prior art, there is a technique described in Japanese Patent Application Laid-Open No. 63-18951. In this technique, a stator coil arranged circumferentially of a brushless motor is partially omitted in a circumferential direction thereof, and the magnetic head moves in the missing portion. However, in order to avoid interference with the magnetic head, simply cutting the stator core and providing notches
The stator core is apt to deform, and the magnetic field acting between the cutting part and the general part between the driving magnet becomes extremely non-uniform, which hinders smooth rotation of the rotor and the rotating shaft. Also, the life of the bearing is shortened.

Further, the technique disclosed in Japanese Patent Application Laid-Open No. 62-230345 removes a part of magnetic poles on the circumference of a brushless motor, but cannot be used for a technique for avoiding interference with a magnetic head. Things.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a thin and thin motor in which interference between a stator iron core of a stator and a magnetic head can be reliably avoided, and a rotor smoothly rotates. is there.

[Means for Solving the Problems] A motor according to the present invention has a rotating shaft rotatably supported, and a ring-shaped drive that rotates integrally with the rotating shaft and generates a magnetic field from the outer peripheral portion in the radial direction of rotation. A rotor on which a plurality of coils are wound around a stator core positioned outside the rotor, and an outer peripheral surface of a predetermined portion of the stator core having an inner periphery. A notch in a concave shape wider than the surface side, and a concave portion formed as a concentric circular arc corresponding to the outer shape of the driving magnet, the rotor-side connecting surface to which the inner peripheral surface is connected. The angle between the straight line passing through the center of the concave portion, which is formed by cutting the outer peripheral surface side of the stator core into a concave shape wider than the inner peripheral surface side, and the center of the rotation axis, and the angle between the core tooth root surface and the concave side It is larger than the angle formed by the root surface.

[Operation] In the present invention, a recess is formed from the outer peripheral surface side to the inner peripheral surface side of a predetermined portion of the stator core of the stator located outside the rotor that rotates integrally with the rotating shaft, and the inner peripheral surface is formed as a concave portion. The side is connected by a stator core, and the rotor-side connecting surface is formed with a concave portion having a concentric circular arc corresponding to the outer shape of the driving magnet. It can move without interference, eliminating the gap on the magnetic disk side of the stator to avoid interference between the stator and the magnetic head, and the gap between the stator core and the rotor driving magnet. Becomes uniform,
The magnetic field acting during this time is made uniform. The angle formed by a straight line passing through the center of the concave portion and the center of the rotating shaft, which is formed by cutting the outer peripheral surface side of the stator core into a concave shape wider than the inner peripheral surface side, and the core tooth side root surface is concave. It is larger than the angle formed by the side root surfaces, and the gap between the connecting portion of the concave portion and the driving magnet becomes uniform, and the magnetic field acting between them becomes uniform, so the rotation of the rotor becomes smooth .

[Example] Hereinafter, an example of the present invention will be described.

FIG. 1 is a sectional view showing a motor according to a first embodiment of the present invention, and FIG. 2 is a plan view showing the motor of FIG.

In the drawing, reference numeral 21 denotes a rotating shaft of an electric motor, and 22 denotes a rotating body having a magnetic disk holding function. The rotating body 22 rotates integrally with the rotating shaft 21. 23 is a disk mounting surface formed on the rotating body 22, 24 is a rotor yoke embedded in the rotating body 22, 25 is a driving magnet made of a permanent magnet disposed on the outer peripheral portion of the rotor yoke 24, and 26 is a rotating magnet. The driving pins are mounted, and the driving pins 26 engage with window holes (not shown) of the rotating plate fixed to the magnetic disk. 31 is a stator core, and 32 is a coil wound around the stator core 31.
The stator core 31 and the coil 32 constitute a stator of the electric motor. Reference numeral 34 denotes a concave portion formed from the outer peripheral surface of the stator core 31 toward the inner peripheral surface, and reference numeral 35 denotes a connecting portion in which the inner peripheral surface of the concave portion 34 is connected by the stator core 31. The rotor-side connecting surface 35a of the connecting portion 35 has a shape corresponding to the outer shape of the rotor. 40 is a frame also serving as a circuit board, 41
Is a bearing mounting member mounted on the frame 40, 42 is a rotating shaft
A sintered oil-impregnated bearing 43 rotatably supports the bearing 21, and a sliding member 43 having a low coefficient of friction interposed between the rotating body 22 and the sintered oil-impregnated bearing 42. 44 is a screw for fixing the stator core 31 to the frame 40, and 45 is a spacer interposed between the stator core 31 and the frame 40.

The motor of this embodiment is configured as described above,
The stator core 31 is capable of transmitting magnetic flux in the direction of the radius of rotation of the electric motor, and forms iron core teeth for 15 angles of the entire circumference divided into 18 equal angular intervals, and 15 coils 32 are formed. It is wound. The outer peripheral surface of the iron core at a position corresponding to the three iron core teeth is a concave portion 34 on the inner peripheral surface side, and the inner peripheral surface side is connected by an iron core to form a connecting portion 35. The concave portion 34 is for the magnetic head to move without interfering with the stator. In the rotor driving magnet 25 located on the inner peripheral side of the stator, for example, the N and S poles are magnetized in the direction of the rotational radius of the rotor for 24 equal parts on the entire circumference. Fifteen coils 32 of the stator are wound every three coils in three phases, and are energized by 120 degrees according to the rotation angle of the rotor to generate a rotation torque in a certain direction.

As described above, the electric motor of this embodiment is of an inner rotor type in which the stator is located outside the rotor, and the stator is formed with the concave portion 34 for moving the magnetic head. Since a gap for avoiding interference between the stator and the rotor and the magnetic disk and the magnetic head as in the case of the electric motor of the type can be omitted, the thickness of the entire electric motor can be reduced.

Further, in this embodiment, the inner peripheral surface side of the concave portion 34 formed from the outer peripheral surface portion to the inner peripheral surface side of the stator core 31 is connected to the stator core 31 to form a connecting portion 35. The rotor-side connecting surface 35a of the connecting portion 35 has a concentric arc shape corresponding to the outer shape of the driving magnet 25 on the outer peripheral portion of the rotor.
Therefore, the gap between the connecting portion 35 of the concave portion 34 and the driving magnet 25 becomes uniform, and the magnetic field acting therebetween is uniform. For this reason, compared with the case where the stator core 31 is simply cut and cut to avoid interference with the magnetic head, a non-uniform magnetic field does not act on the rotor. The life of the shaft 21 and the sintered oil-impregnated bearing 42 is also extended.

As described above, the motor of this embodiment is a sintered oil-impregnated bearing.
The rotating shaft 21 rotatably supported by 42 and this rotating shaft
A rotor in which a ring-shaped driving magnet 25 that rotates integrally with and generates a magnetic field in the direction of the radius of rotation on the outer peripheral portion is disposed, and a plurality of stator cores 31 are located outside the rotor and are disposed outside the rotor. A stator around which the coil 32 is wound, and a predetermined portion of the stator core 31 (a concave portion is formed from the outer peripheral surface side to the inner peripheral surface side of the movable portion of the magnetic head, and the inner peripheral surface side is the stator core 31 At the rotor side connecting surface of the connecting portion 35
35a is provided with a concave portion 34 formed as a concentric arc corresponding to the outer shape of the driving magnet 25.

That is, the electric motor of this embodiment has a stator core 31 of a coil.
A concave portion is formed from the outer peripheral surface side to the inner peripheral surface side of the movable portion of the magnetic head, and the inner peripheral surface side is connected to the stator core 31 to form a concave portion 34, and furthermore, The rotor-side connecting surface 35a of the connecting portion 35 of the concave portion 34 is a concentric arc corresponding to the outer shape of the driving magnet 25.

Therefore, the magnetic head moves the stator core
The motor can be moved without interfering with the stator 31 and the gap on the magnetic disk side of the stator for avoiding the interference between the stator and the magnetic head as in the prior art can be omitted. be able to. Moreover, the concave portion
Since the gap between the connecting portion 35 of 34 and the driving magnet 25 becomes uniform, and the magnetic field acting between them becomes uniform, the rotor rotates smoothly, and the life of the rotating shaft 21 and the sintered oil-impregnated bearing 42 becomes longer. Also extend.

As a result, it is possible to promote a reduction in the thickness of the entire electric motor, a smooth rotation of the rotor, and a longer life of the rotating shaft and the bearing.

FIG. 3 is a plan view showing another example of the connecting portion of the electric motor according to the first embodiment of the present invention. In the figures, FIG. 1 and FIG.
The same reference numerals and symbols as those in the drawings denote the same or corresponding components as those in FIGS. 1 and 2.

In the drawing, reference numeral 35b denotes an anti-rotor side connecting surface 35b of the connecting portion 35 of the concave portion 34, and the anti-rotor side connecting surface 35b is a concentric arc corresponding to the outer shape of the driving magnet 25 on the outer peripheral portion of the rotor. It has become. That is, the anti-rotor side connecting surface 35b is also concentric with the rotor side connecting surface 35a. Other configurations are the same as those of the above embodiment.

Therefore, the motor in this case is also an inner rotor type in which the stator is located outside the rotor, and the stator has a concave portion 34 for moving the magnetic head. As described above, a gap for avoiding interference between the stator and the rotor and the magnetic disk and the magnetic head can be omitted, so that the thickness of the entire electric motor can be reduced.

Moreover, also in this case, similar to the above embodiment,
The inner peripheral surface side of the concave portion 34 formed from the outer peripheral surface portion to the inner peripheral surface side of the stator core 31 is connected to the stator core 31 by the connecting portion.
It is 35. In this case, the rotor-side connecting surface 35a and the anti-rotor-side connecting surface 35b of the connecting portion 35 are driven magnets.
25 are concentric arcs according to the outer shape, and the connecting portion 35 has a uniform width. Therefore, in this embodiment as well, the gap between the connecting portion 35 of the concave portion 34 and the driving magnet 25 becomes uniform, and the magnetic field acting therebetween is made uniform. In particular, the connecting portion 35 is made uniform. Because of the width, the magnetic field acting on the rotor is more uniform than in the above embodiment, and the rotation of the rotor becomes smoother.

As described above, the electric motor of this embodiment includes the same rotary shaft 21, rotor, and stator as in the above-described embodiment, and the stator core 31 has a magnetic head movable portion from the outer peripheral surface side. A recess is formed toward the inner peripheral surface, and this inner peripheral surface is
A concave portion 34 having a predetermined shape is formed by being connected at 31, and the rotor-side connecting surface 35a and the anti-rotor-side connecting surface 35b of the connecting portion 35 of the concave portion 34 are formed on the outer shape of the driving magnet 25. The corresponding concentric arcs are formed.

Therefore, similarly to the above-described embodiment, the magnetic head can move in the concave portion without interfering with the stator core 31, and the entire motor can be reduced in thickness. Since the magnetic field acting between the connecting portion 35 and the driving magnet 25 is further uniformed, the rotor rotates more smoothly. Therefore, the thickness of the entire motor can be reduced, and the rotation of the rotor can be smoothly performed, and the life of the rotating shaft and the bearing can be further extended.

FIG. 4 is a plan view showing a concave portion of the electric motor according to the first embodiment of the present invention. In the drawings, the same reference numerals and symbols as those in FIGS. 1 to 3 denote the same or corresponding components as those in FIGS. 1 to 3.

In the drawing, 37 is a center line connecting the center of the rotating shaft 21 and the center of the concave portion 34, and 38 is a general portion and a concave portion of the stator core 31.
It is a base portion of the connecting portion 34 with the connecting portion 35. 38a is a core tooth side root surface located on the core tooth side of the root portion 38, and 38b is a root portion 38
Is a concave-shaped base surface located on the concave-shaped portion 34 side. In this embodiment, the width of the connecting portion 35 is smaller than the width of the base portion.
The width of 38 is wider. Other configurations are the same as those of the above embodiments.

Therefore, the electric motor of this embodiment is also of the inner rotor type in which the stator is located outside the rotor, and the stator is provided with a concave portion 34 for moving the magnetic head, so that the conventional outer rotor type is used. Since the gap for avoiding the interference between the stator and the rotor and the magnetic disk and the magnetic head as in the electric motor described above can be omitted, the thickness of the entire electric motor can be reduced.

Moreover, in this embodiment, similarly to the above embodiments, the inner peripheral surface side of the concave portion 34 formed from the outer peripheral surface portion to the inner peripheral surface side of the stator core 31 is connected by the coil core 31 and the connecting portion. It is 35. Further, the rotor-side connecting surface 35a of the connecting portion 35 of this embodiment has a concentric arc shape corresponding to the outer shape of the driving magnet 25. In addition, the root portion 38 of the connecting portion 35 is wider than the connecting portion 35, and further, the root portion 38 has a connecting portion with the general portion of the coil core 31 than a connecting portion with the connecting portion 35. It is wide. As a specific shape, the angle θ2 formed by the core tooth side root surface 38a with respect to the center line 37 connecting the center of the rotating shaft 21 and the center of the concave portion 34 is larger than the angle θ1 formed by the concave side root surface 38b. (Θ2>
θ1). Therefore, the gap between the connecting portion 35 of the concave portion 34 and the driving magnet 25 becomes uniform, and the magnetic field acting between them becomes uniform, so that the rotation of the rotor becomes smooth and the connecting portion 35 Since the base portion 38 is wider than the connecting portion 35, the rigidity of the entire stator core 31 increases.

As described above, the electric motor of this embodiment includes the same rotary shaft 21, rotor, and stator as in the above embodiments, and the outer peripheral surface of the movable portion of the magnetic head of the stator core 31. A concave portion is formed from the side toward the inner peripheral surface side, and the inner peripheral surface side is connected to the stator core 31 to form a concave portion 34 having a predetermined shape,
Moreover, the rotor-side connecting surface 35 of the connecting portion 35 of the concave portion 34
The a and the anti-rotor side connecting surface 35b are concentric arcs according to the outer shape of the driving magnet 25, and the root portion 38 of the connecting portion 35 is wider than the connecting portion 35.

Therefore, similarly to the above embodiment, the thickness of the entire motor can be reduced, the rotor rotates smoothly, and the root portion 38 of the connecting portion 35 is wider than the connecting portion 35. The strength of is improved. That is, the thickness of the entire motor can be reduced, the rotation of the rotor can be smoothly performed, the life of the rotating shaft and the bearing can be prolonged, and the strength of the stator core 31 can be improved.

[Effects of the Invention] As described above, the electric motor of the present invention includes the rotor that rotates integrally with the rotatably supported rotating shaft, and the stator that is located outside the rotor. A concave portion is formed from the outer peripheral surface side to the inner peripheral surface side of a predetermined portion of the stator core, and the inner peripheral surface side is connected by the stator core, and the rotor side connecting surface is a concentric arc corresponding to the outer shape of the driving magnet. The magnetic head can move inside the concave portion without interfering with the stator core, and the stator for avoiding the interference between the stator and the magnetic head can be provided. Since the gap on the magnetic disk side can be omitted, the thickness of the entire electric motor can be reduced. The angle formed by a straight line passing through the center of the concave portion and the center of the rotating shaft, which is formed by cutting the outer peripheral surface side of the stator core into a concave shape wider than the inner peripheral surface side, and the core tooth side root surface is concave. It is made larger than the angle formed by the side root surface, the gap between the connecting part of the concave part and the driving magnet becomes uniform, and the magnetic field acting between them is uniform, so the rotation of the rotor becomes smooth, The life of the rotating shaft and the bearing is extended.

[Brief description of the drawings]

1 is a sectional view showing a motor according to a first embodiment of the present invention, FIG. 2 is a plan view showing the motor of FIG. 1, and FIG. 3 is a plan view showing a motor according to a second embodiment of the present invention. FIG. 4 is a plan view showing a concave portion of a motor according to a first embodiment of the present invention, and FIG. 5 is a sectional view showing a conventional motor. In the figure, 21: rotating shaft, 22: rotating body 23: disk mounting surface, 24: rotor yoke 25: driving magnet, 31: stator core 32: coil, 34: concave portion 35: connecting portion, 35a: rotor Side connection surface 35b: anti-rotor side connection surface, 37: center line 38: root, 38a: iron core side root 38b: concave side root, 42: sintered oil-impregnated bearing. In the drawings, the same reference numerals and symbols indicate the same or corresponding parts.

Claims (1)

(57) [Claims] A rotor provided with a rotating shaft rotatably supported, and a ring-shaped driving magnet which rotates integrally with the rotating shaft and generates a magnetic field from an outer periphery in a radial direction of rotation; A stator in which a plurality of coils are wound around a stator core, which is located outside the rotor, and an outer peripheral surface side of a predetermined portion of the stator core is notched in a concave shape wider than an inner peripheral surface side. ,
A concave portion formed as a concentric arc corresponding to the outer shape of the driving magnet, wherein a rotor-side connecting surface to which the inner peripheral surface is connected is provided, and an outer peripheral surface of the stator core is an inner peripheral surface. The angle formed by a straight line passing through the center of the concave portion cut out in a concave shape wider than the center of the rotary shaft and the core tooth root surface around which the coil is wound is defined by the concave root surface. An electric motor characterized by being larger than the angle.