JP2621640B2 - 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. 2 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,
4 is a yoke of the rotor 3, 5 is a permanent magnet disposed on the outer periphery of the yoke 4, 6 is a screw fixing the rotor and the rotating shaft 1, 7 is a stator of the electric motor, and 8 is a stator of the electric motor. An iron core of the stator 7, a coil 9 wound around the iron core 8, a bearing mounting member 10, and bearings 11 and 12 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 detection element provided on the frame 13, and 17 denotes an index detection magnet provided on the rotor 3. The index detection element 16 and the index detection 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.

[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 (not shown). Therefore, there is a limit in reducing the thickness of the electric motor. For this reason, a thin inner rotor type electric motor in which the stator 7 is located outside the rotor 3 has been considered.

However, in this type of electric motor, the rotor is mounted on the frame via the bearing mounting member. In addition, the end face of the bearing mounting member is exposed from the frame, and the ends of the bearing and the rotating shaft are also exposed from the frame. For this reason, there is a possibility that foreign matter may enter from the outside, and it is necessary to protect these parts. However, simply adding a protective member to the outside of the frame has a disadvantage that the thickness of the motor increases.

On the other hand, as another prior art, there is a technique disclosed in JP-A-52-6914. This publication discloses a technique in which an outer end surface of a bearing mounting member of a rotor is projected in a direction opposite to the rotor, and a decorative plate is stretched there. Also in this technique, there is a problem that the outer end surface protrudes from the frame and the thickness of the electric motor increases.

Japanese Patent Application Laid-Open No. 2-250653 discloses a technique in which a bearing of the rotor is projected in a direction opposite to the rotor, and a thrust plate is stretched there. In this technology,
The outer end surface of the bearing protrudes from the frame, causing a problem that the thickness of the electric motor increases.

Japanese Utility Model Application Laid-Open Publication No. Sho 62-156910 discloses a technique in which a bearing of a rotor is projected outward from the rotor, and the bearing provided therein is sealed. Also in this technique, there is a problem that the bearing protrudes from the frame and the thickness of the electric motor increases.

Therefore, the present invention provides an end face of a bearing mounting member of a rotor,
It is an object of the present invention to provide a thin and thin electric motor that can protect the bearing and the end of the rotating shaft.

[Means for Solving the Problems] The electric motor according to the present invention includes a rotating shaft rotatably supported, and a ring-shaped driving magnet which rotates integrally with the rotating shaft and generates a magnetic field on an outer peripheral portion. A rotor provided, a stator located on the outer periphery of the rotor, a plurality of coils wound around a stator core, the stator is fixed and the rotor is pivotally supported, An outer end surface of a bearing mounting member of a rotor includes a frame having a step of a predetermined dimension near the rotor, and a protective film member stretched over the step of the frame and having a thickness substantially equal to the step. .

[Operation] In the present invention, a rotor having a ring-shaped driving magnet which rotates integrally with a rotatably supported rotating shaft and generates a magnetic field on an outer peripheral portion, and an outer periphery of the rotor , A stator formed by winding a plurality of coils around a stator core is fixed, the rotor is supported by a shaft, and an outer end surface of a bearing mounting member of the rotor has a step of a predetermined dimension near the rotor. Since the protective film member having substantially the same thickness as the step is stretched over the step, the end surface of the bearing mounting member of the rotor, the end of the bearing and the rotating shaft are not exposed from the frame. Protected by the protective film member, foreign matter can be prevented from entering from outside, and the outer surface of the frame is substantially flat, so that the thickness of the motor does not increase.

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

FIG. 1 is a sectional view showing an electric motor according to one embodiment of the present invention.

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, 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 40 denotes a frame also serving as a circuit board, and an outer surface 40a of the rotor of the frame 40 on the bearing mounting member 41 side is formed with a step 40b near the rotor. The dimension of the step 40b is approximately 0.05 to 0.3 mm with respect to the other outer surface 40a, and usually,
It is formed by a narrowing process such as a press process. Also,
A rotor mounting hole 40c is formed in the center of the step 40b. 41 is a bearing mounting member mounted on the rotor mounting hole 40c of the frame 40, 42 is a sintered oil-impregnated bearing that rotatably supports the rotating shaft 21, 43 is between the rotating body 22 and the sintered oil-impregnated bearing 42. It is a sliding member with a low coefficient of friction interposed. 44 is the stator core 31
Is fixed to the frame 40, 45 is a spacer interposed between the stator core 31 and the frame 40, 46 is a protective film member stretched over the step 40b of the frame 40, and has a thickness of the step 40b.
And the thickness is substantially the same. Reference numeral 50 denotes a magnetic shielding plate made of a ferromagnetic electromagnetic shielding material such as an iron plate, which covers an exposed portion of a coil 32 wound around a stator core 31 and a disk mounting surface 23 of a rotor driving magnet 25. Cover the exposed side.

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. Then, a concave portion is formed from the outer peripheral surface to the inner peripheral surface side of the core corresponding to the three iron core teeth, and the inner peripheral surface side is connected by the iron core. This concave portion is for the magnetic head (not shown) 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. Stator 15
The coils 32 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 rotational torque in a certain direction.

As described above, the electric motor of this embodiment is of the inner rotor type in which the stator is located outside the rotor, and the stator is formed with the concave portion for moving the magnetic head, and 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, the rotor mounting hole 40 of the frame 40 is
The rotor is mounted on c via a bearing mounting member 41 and a sintered oil-impregnated bearing. Then, the outer surface 40a of the frame 40 near the rotor mounting hole 40c near the rotor is approximately 0.
It has a step 40b with a size of 05 to 0.3 mm. Also, the step
A protective film member 46 having substantially the same thickness as the step 40b is stretched over the step 40b. Therefore, the end face of the bearing mounting member 41 of the rotor, the end of the sintered oil-impregnated bearing 42 and the end of the rotating shaft 21 are connected to the outer face 40 of the frame 40.
Not exposed from a. That is, the bearing mounting member 41 of the rotor
, The end portions of the sintered oil-impregnated bearing 42 and the rotating shaft 21 are covered and protected by a protective film member 46. Therefore, unlike the conventional case, no foreign matter enters from the outside. Further, the outer surface 40a of the frame 40 is substantially flat, and the thickness of the electric motor does not increase due to the protective film member 46.

As described above, the motor of this embodiment is a sintered oil-impregnated bearing.
A rotating shaft 21 rotatably supported by 42;
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. The stator on which the coil 32 is wound, the stator and the rotor are mounted, and the outer surface 40a of the rotor on the bearing mounting member 41 side near the bearing mounting member 41 has a predetermined dimension (approximately 0.05
A frame 40 having a step 40b of about 0.3 mm) and a protective film member 46 having substantially the same thickness as the step 40b stretched over the step 40b of the frame 40 are provided.

That is, the electric motor of this embodiment has an outer surface 40a on the bearing mounting member 41 side of the rotor of the frame 40 on which the rotor that rotates integrally with the rotating shaft 21 and the stator that is located outside the rotor are mounted. Has an error 40b with a dimension of approximately 0.05 to 0.3 mm near the rotor, and a protective film member having substantially the same thickness as the step 40b in the step 40b.
46 are stretched.

Therefore, in this embodiment, the end face of the bearing mounting member of the rotor, the end of the bearing and the rotating shaft are protected by the protective film member 46 without being exposed from the frame 40, and foreign substances can be prevented from entering from outside. Moreover, the outer surface 40a of the frame 40
Is in a substantially flat state, and the thickness of the electric motor does not increase.

As a result, a thin and thin motor having high reliability and safety is obtained.

By the way, in the above-described embodiment, the step of the frame is formed by the narrowing process such as the press working, but the present invention is not limited to this working method. Also, the size of this step may be approximately equal to the thickness of the protective film member, but if it is too large, it may increase the thickness of the electric motor, so it is approximately 0.05 to 0.3 mm as described above. Is preferred. Further, the range of the step 40b may be a range including the entire end face of the bearing mounting member.

[Effects of the Invention] As described above, the electric motor of the present invention includes a rotating shaft rotatably supported, a rotor that rotates integrally with the rotating shaft,
A rotor positioned outside the rotor, a frame having a step of a predetermined dimension, and a protective film member stretched over the step, the rotor rotating integrally with the rotation shaft, and the stator fixed In the frame on which the rotor is supported, the outer surface of the rotor on the bearing mounting member side has a step of a predetermined size near the rotor, and a protective film member having substantially the same thickness as the step is stretched over the step. With this simple and simple configuration, the end surface of the bearing mounting member of the rotor, the end of the bearing and the rotating shaft are protected by the protective film member without being exposed from the frame, and foreign matter can be prevented from entering from the outside. Therefore, reliability and safety are improved, and the outer surface of the frame is substantially flat, so that the thickness of the motor does not increase, thereby contributing to a thin motor.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a motor according to an embodiment of the present invention, and FIG. 2 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: drive magnet, 31: stator core 32: coil, 40: frame 40a: outer surface, 40b: step 46: protective film It is a member. In the drawings, the same reference numerals and symbols indicate the same or corresponding parts.

Claims (1)

(57) [Claims] A rotating shaft rotatably supported; a rotor having a ring-shaped driving magnet that rotates integrally with the rotating shaft and generates a magnetic field on an outer peripheral portion; and the rotor. A plurality of coils wound around a stator core, and the stator is fixed and the rotor is supported, and an outer end face of a bearing mounting member of the rotor rotates. An electric motor comprising: a frame having a step with a predetermined dimension near a child; and a protective film member having substantially the same thickness as the step, which is stretched over the step of the frame.