JPH04172953A - Motor - Google Patents

Abstract

PURPOSE:To obtain a thin motor in which the end face at a bearing fixing part of a rotor and the ends of the bearing and the rotary shaft are protected by providing a step of predetermined dimension, closely to the rotor, on the outer face at the bearing fixing part of a shell member and stretching a protective film member across the step in a magnetic disc drive motor. CONSTITUTION:A motor comprises a rotor arranged with a driving magnet ring 25 rotatable integrally with a rotary shaft 21, a stator wound with a plurality of coils 32 and located on the outside of the rotor, a frame 40 for mounting the stator and the rotor having a step 40b of predetermined dimension, closely to the rotor, on the outer face 40a at a bearing fixing position in the proximity of a bearing fixing member 41 of the rotor, and a thin film 46 (protective film member) substantially as thick as the step 40b stretched across the step 40b of the frame 40. According to the constitution, end face at the bearing fixing part of the rotor and the ends of the bearing and the rotary shaft are not exposed from the frame 40 but protected with the thin film 46 without increasing the thickness of motor.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electric motor, and in particular to a motor used in a device having a magnetic head for reading and writing magnetic recording signals on a magnetic disk, which is a disc-shaped recording medium. This invention relates to an electric motor for driving rotation of a recording medium.

[Prior art] As a conventional electric motor of this type, Utility Model Application No. 60-13586
The technology published in Publication No. 3 can be mentioned.

FIG. 2 is a sectional view showing a conventional electric motor.

In the figure, (1) is the rotating shaft of the electric motor, (2) is a rotating body that has a magnetic disk holding function;
) rotates integrally with the rotating shaft (1). (3) is the rotor of the electric motor, (4) is the yoke of the rotor (3), (
5) is a permanent magnet arranged on the outer periphery of the yoke (4), (
6) is the screw fixing the rotor (3) and the rotating shaft (1), (7) is the stator of the motor, and (8) is the stator (
7) is the iron core, (9) is the coil wound around the iron core (8),
(10) is a bearing mounting member, and (11) and (12) are bearings that are mounted on the bearing mounting member (11) and rotatably support the rotating shaft (1). (13) is the frame of the electric motor, (
14) is a screw fixing the stator (7) and the bearing mounting member (1o), (15) is a drive pin attached to the rotating body (2), and this drive pin (15) is a screw that fixes the stator (7) and the bearing mounting member (1o). It engages with a window hole (not shown) in a rotary plate fixed to the rotary plate.

(16) is an index detection element disposed on the frame (13), (17) is an index detection magnet disposed on the rotor (3), and this index detection element (
16) and the index detection magnet (17) generate one pulse per rotation.

The electric motor with the above configuration has a rotor (3) on the outside of the stator (7).
The permanent magnet (5) of the rotor (3) generates a magnetic field in the radial direction of rotation.

[Problem to be solved by the invention] In the conventional outer rotor type electric motor as described in 1.
A certain amount of space was required between the rotor (3) and the stator (7). Further, a frame (13) or a bearing mounting member (10) was interposed between the stator (7) and rotor (3) and the magnetic disk and magnetic head (not shown). Therefore, there was a limit to how thin the electric motor could be. For this reason, it has been considered to create a thin inner rotor type electric motor in which the stator (7) is located outside the rotor (3).

However, in this type of electric motor, the rotor is attached to the frame 1 via a bearing attachment part. Furthermore, the end face of this bearing mounting portion is exposed from the frame, and the ends of the bearing and rotating shaft are also exposed from the frame. Therefore, there is a risk 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 the problem of increasing the thickness of the motor.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a thin electric motor that can protect the end face of the rotor bearing mounting portion, the bearing, and the end of the rotating shaft, and that is thin.

[Means for Solving the Problems] The electric motor according to the present invention has a rotatably supported rotary shaft (21), rotates integrally with the rotary shaft (21), and applies a magnetic field to the outer circumference in the direction of the rotation radius. A rotor is provided with a ring-shaped driving magnet (25) and a plurality of coils (3
2) a stator on which is wound, an external member to which the stator and rotor are attached, and an outer surface of a bearing mounting portion of the rotor having a step of a predetermined size closer to the rotor; and a step between the external member. A protective film member having substantially the same thickness as the step is provided.

[Function] In the present invention, the outer surface of the bearing attachment portion of the rotor of the external member to which the rotor that rotates integrally with the rotating shaft (21) and the stator located outside the rotor is attached rotates. There is a step of a predetermined size near the child, and a protective film member of approximately the same thickness as the step is stretched over this step. It is protected by the protective film member without being exposed from the external member, preventing foreign matter from entering from the outside, and since the outer surface of the external member is substantially flat, the thickness of the motor does not increase.

[Example J Examples of the present invention will be described below.

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

In the figure, (21) is a rotating shaft of an electric motor, and (22) is a rotating body having a magnetic disk holding function, and this rotating body (22) rotates integrally with the rotating shaft (21). (2
3) 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 consisting of a permanent magnet arranged on the outer periphery of the rotor yoke (24), and (26) is a rotating body (
This drive pin is attached to the drive pin (22).
6) engages with a window hole (not shown) in a rotary plate fixed to the magnetic disk. (31) is a stator core, (32) is a coil wound around the stator core (31), and the stator core (31) and coil (32) constitute the stator of the motor. .

(40) is a frame that also serves as a circuit board, and the outer surface (40a) of the rotor bearing attachment part of this frame (40)
A step (40b) is formed near the rotor. The dimension of this step (40b) is approximately 0.05 to 0.0 mm with respect to the other outer surface (40a). 3 in order, and is usually formed by drawing processing such as press processing. Also, this step (40b
) is provided with a rotor mounting hole (40c) in the center thereof.

(41) is the rotor mounting hole (40c) of the frame (4o)
The bearing mounting member (42) attached to the rotating shaft (21
), and (43) is a sliding member with a low friction coefficient interposed between the rotating body (22) and the sintered oil-impregnated bearing (42). (44) is the stator core (3
1) to the frame (40), (45) is a spacer interposed between the stator core (31) and the frame (40), and (46) is the step (40b) of the frame (4o).
), and its thickness is the thickness between the step (40b) and the gap between the steps (40b). (5o) is a magnetic shielding plate made of a ferromagnetic electromagnetic shielding material such as an iron plate, and the stator core (
31), and also covers the exposed portion of the rotor drive magnet (25) on the disk mounting surface (23) side.

The electric motor of this embodiment is constructed as described above, and the stator core (31) is capable of passing magnetic flux in the direction of the rotation radius of the electric motor. Iron core teeth are formed at 15 angles, and 15 coils (32) are wound around the iron core teeth. A concave portion is formed from the outer circumferential surface of the core to the inner circumferential surface at locations corresponding to the three core teeth, and the inner circumferential surface is connected by the core. This concave portion allows the magnetic head (not shown) to move without interfering with the stator. Further, the rotor driving magnet (25) located on the inner circumferential side of the stator has, for example, 24 equally divided N and S poles magnetized in the rotation radius direction of the rotor. The 15 coils (32) of the stator are wound every second into three phases, and the 120 coils (32) are wound in three phases to match the rotation angle of the rotor.
Once energized, it generates rotational torque in a fixed direction.

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

Moreover, in this embodiment, the rotor is mounted in the rotor mounting hole (40c) of the frame (4o) via a bearing mounting member (41) and a sintered oil-impregnated bearing (42). The outer surface (40a) of this frame (4o) in the vicinity of the rotor mounting hole (40c) is approximately 0.05~
It has a step (40b) with a size of 0.3 mm. Also,
A thin film (46) having substantially the same thickness as the step (40b) is stretched over the step (40b). Therefore, the end surface of the rotor bearing mounting member (41), the sintered oil-impregnated bearing (42), and the end of the rotating shaft (21) are connected to the outer surface (40) of the frame (40).
a) Not completely exposed.

That is, the end face of the rotor bearing mounting member (41), the sintered oil-impregnated bearing (42), and the end of the rotating shaft (21) are coated with the thin film (46).
covered and protected by Therefore, foreign matter does not enter from the outside unlike in the conventional case. Further, the outer surface (40a) of the frame (4o) is substantially flat, and the thickness of the motor is not increased by this thin film (46).

As mentioned above, the electric motor of this example has a sintered oil-impregnated bearing (
a rotating shaft (21) rotatably supported by 42);
A ring-shaped driving magnet that rotates integrally with the rotating shaft (21) and generates a magnetic field in the rotational radial direction on its outer periphery) (
25), a solid electron located outside the rotor and having a plurality of coils (32) wound around a stator core (31), and a rotor on which the stator and rotor are installed. The outer surface (40a) of the bearing attachment part near the bearing attachment member (41) of the rotor has a predetermined dimension (approximately 0, 05
~0. 3mm) (7) A frame (40) (external member) having a step (40b), and the frame (40) (
The step (40b) is stretched over the step (40b) of the external member).
40b) and a thin film (46) (protective film member) having approximately the same thickness.

That is, the electric motor of this embodiment has a rotor of a frame (4o) (external member) on which a rotor that rotates integrally with the rotating shaft (21) and a stator located outside the rotor are mounted. The outer surface (40a) of the bearing mounting portion is approximately 0.0 mm closer to the rotor.
It has a step (40b) with a size of 0.05 to 0.3 mm, and a thin film (40b) having approximately the same thickness as the step (40b) is formed on this step (40b).
46) (protective film member) is stretched.

Therefore, in this embodiment, the end face of the rotor bearing mounting part, the bearing, and the end of the rotating shaft are not exposed from the frame (40) and are protected by the thin film (46) to prevent foreign matter from entering from the outside. can.

Moreover, the outer surface (40a) of the frame (40) is substantially flat, and the thickness of the electric motor does not increase.

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

Incidentally, in the above embodiment, the step of the external member is formed by a narrowing process such as a press process, but the process is not limited to this process. In addition, the dimension of this step should be approximately equal to the thickness of the protective film member, but if it is too large, it may conversely increase the thickness of the motor, so as mentioned above, the dimension of this step should be approximately 0.05 to 0.3 mm. Preferably, the dimensions are the same. Furthermore,
The range of this step (40b) may be any range that includes the entire bearing mounting area.

[Effects of the Invention] As described above, the electric motor of the present invention includes a rotatably supported rotating shaft, a rotor that rotates integrally with the rotating shaft, and a stator located outside the rotor. An external member comprising an external member having a step of a predetermined size and a protective film member stretched over the step, to which a rotor that rotates integrally with a rotating shaft and a stator located outside the rotor are attached. The outer surface of the rotor bearing attachment part of the member has a step of a predetermined size near the rotor, and a protective film member with approximately the same thickness as the step is stretched over this step.This simple structure allows rotation. The end face of the child bearing mounting part, the end of the bearing, and the rotating shaft are protected by the protective film member without being exposed from the external member, and foreign matter can be prevented from entering from the outside, improving reliability and safety. However, since the outer surface of the external member is substantially flat, the thickness of the motor does not increase, which contributes to making the motor thinner.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an electric motor according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional electric 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 40: frame 40a: outer surface 40b = step 46: thin film. In the drawings, the same reference numerals and the same symbols indicate the same or equivalent parts. Agent: Patent attorney Masuo Oono and 2 others

Claims (1)

[Scope of Claims] A rotating shaft rotatably supported; a rotor that rotates integrally with the rotating shaft and is provided with a ring-shaped driving magnet that generates a magnetic field on its outer periphery; and the rotor. a stator located on the outside of the rotor and having a plurality of coils wound around the stator core; the stator and the rotor being attached; What is claimed is: 1. An electric motor comprising: an external member having: a protective film member extending over a stepped portion of the external member and having substantially the same thickness as the stepped portion.