JPH07231603A - Small motor - Google Patents

Abstract

PURPOSE:To give a sufficient side pressure to a shaft and to surely prevent the shaft from being vibrated axially by a method wherein a second magnetic substance mounted on the inner circumferential face of a casing to pull a first magnetic substance to the outside in a certain radial direction by a magnetic force is provided to face the first magnetic substance. CONSTITUTION:Inside 40 a casting 3, a first magnetic substance 41 attached to a shaft 7 is installed, and a second magnetic substance 42 attached to the inner circumferential face of the casing to face the first magnetic substance 41 is arranged and installed. Then, the second magnetic substance 42 pulls the first magnetic substance 41 by magnetic force to the outside H in a certain radial direction, and it gives a side pressure to the shaft 7. Thereby, the sufficient side pressure is given to the shaft 7, and it is possible to surely prevent the shaft 7 form being vibrated axially.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor, and more particularly to a small motor used in audio / visual equipment such as a CD player (compact disc player).

[0002]

2. Description of the Related Art A disc player such as a CD player is
By rotating a disc in which information is stored at a high density, such as a CD (compact disc), an LD (laser disc), a CD-ROM (compact disc-ROM) or an MD (mini disc), with a small motor,
The information is read and reproduced.

Small motors are widely used in various fields other than the above-mentioned disc reproducing apparatus, and have been advanced in higher performance, smaller size and lighter weight. The small motor has a permanent magnet mounted on the inner surface of the casing, and rotatably supports the rotating shaft of the rotor by two bearings provided at both ends of the casing.

The rotating shaft is in sliding contact with the inner peripheral surface of the bearing,
In order to smoothly rotate the rotating shaft, a minute clearance (gap) is secured between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bearing. Due to this clearance, when the rotor makes a rotary motion, the rotary shaft and the rotor vibrate in a direction (radial direction) at right angles to the central axis direction. When the rotary shaft causes axial vibration, a disk such as a CD mounted on a turntable attached to the rotary shaft also vibrates in the radial direction, and vibration of the entire motor also occurs.

In the disc reproducing apparatus having a structure in which a belt is stretched between a small motor and a turntable to transmit power, the belt always pulls the rotary shaft of the small motor in the radial direction. The shaft vibration as described above is relatively unlikely to occur. On the other hand, there are many so-called direct drive type disc reproducing devices in which a turntable is directly attached to the rotary shaft of a small motor to rotate the disc. In such a disc reproducing apparatus, a small motor is installed in the vertical direction to rotate the disc on the turntable in a horizontal plane.

By the way, since the pitch of the groove of the track of the CD is very small, for example, about 1.6 μm (micrometer), when the CD oscillates in the horizontal direction beyond the dimension of the pitch due to the axial vibration of the rotary shaft, The pickup device could not read the recorded information on the CD, which could cause a reproduction error.

The minimum value of the clearance for smoothly rotating the rotary shaft in the bearing is usually several micrometers (for example, 5 μm). Further, when the small motor is installed vertically, the total weight of the rotor, the turntable and the disk does not act as a side pressure (pressure acting laterally, for example, at right angles to the central axis) on the rotating shaft. Therefore, the shaft vibration is likely to occur, and the reproduction error is likely to occur.

Conventionally, by applying a spring mounted in a housing to a spring bearing of a rotary shaft, a mechanical side pressure is applied to the rotary shaft to reduce axial vibration of the rotary shaft due to a clearance between the rotary shaft and a bearing. Another small motor has been proposed (see Japanese Patent Laid-Open No. 60-200740).

[0009]

However, in the small motor having such a structure, since the lateral pressure is mechanically applied to the rotary shaft, mechanical noise due to mechanical friction at the contact portion between the spring and the spring receiver is generated. Due to the occurrence and wear of the contact portion, the biasing force gradually decreases, the side pressure applied to the rotating shaft also decreases, and there is a problem that the shaft vibration increases.

On the other hand, Japanese Utility Model Laid-Open No. 59-28259 and Japanese Utility Model Laid-Open No. 62-107543 propose a motor having a structure in which a lateral pressure by magnetism is applied to a rotary shaft. Particularly in a disc reproducing apparatus, when a motor is driven, a rotary motion part including a rotor including a rotary shaft, a turntable and a disk rotates, but since the total mass of these rotary motion parts is considerably large, a sufficient lateral pressure is applied. Unless added, it is difficult to prevent shaft vibration of the rotary shaft.

However, since the rotary shaft of the motor of the former publication is attracted by the permanent magnet, the facing area is small and the magnetic force is also small. Therefore, it has been difficult to apply a sufficient lateral pressure to the rotary shaft. Further, in recent years, particularly in a small motor for a disk reproducing device, stainless steel is often used as a material of the rotating shaft in order to smooth the surface of the rotating shaft and reduce the clearance with the bearing. Although this stainless steel rotating shaft is a magnetic material, it is insufficient to attract the rotating shaft with a permanent magnet to exert the required lateral pressure effect.

On the other hand, the motor disclosed in the latter publication has a structure in which a magnetic body is attached to the rotating shaft and the magnetic body is attracted by a magnet provided outside the casing. However, since the magnetic body and the magnet are small and the clearance between them is not taken into consideration, only a small magnetic force is generated, and it is difficult to apply sufficient lateral pressure to the rotating shaft as in the motor of the former publication. It was In addition, since the magnetic body and the magnet are attached to the outside of the casing, there is a problem that the magnetic body and the magnet interfere when the motor is incorporated into the frame of the disc reproducing apparatus.

[0013] Of the disc reproducing apparatuses, portable portable ones are particularly required to be small, thin and lightweight. For example, CD (diameter is about 120m
MD (about 64 mm in diameter), which is about half the size of m)
In the mini-disc system for reproducing a disc, a portable disc reproducing device that fits in a pocket has already been proposed. In such a disc reproducing apparatus, it is required to further shorten the entire length of the small motor mounted in the apparatus to reduce the size, thickness and weight.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a small motor capable of reliably preventing the shaft vibration of the rotary shaft by giving a sufficient lateral pressure to the rotary shaft. And Another object of the present invention is to reduce the motor length by shortening the overall motor length. Furthermore,
Another object of the present invention is to reduce the mass of the rotary motion part to reduce the moment of inertia.

[0015]

In order to achieve the above object, a small motor of the present invention has a rotating shaft rotated by a stator mounted on an inner peripheral surface of a casing and a bearing device mounted on the casing. In a small motor including a rotor that is freely supported and faces the stator, a first magnetic body that is attached to the rotary shaft and is disposed inside the casing, and the first magnetic body. And a second magnetic body that is attached to the inner peripheral surface of the casing so as to face the first magnetic body and pulls the first magnetic body outward in the fixed radial direction by a magnetic force.

[0016] Preferably, the first magnetic body has an outer peripheral edge portion whose entire circumference is thick in the axial direction and an inner plate-like portion which is thin, and has a circular shape as a whole. Further, it is preferable that a plurality of openings be formed in the plate-like portion inward of the outer peripheral edge portion of the first magnetic body.

The stator is formed by two arc segment-shaped permanent magnets for rotation, and the permanent magnets for rotation are integrally extended in parallel with the central axis direction to form extension portions.
The extending portion may be the second magnetic body. Further, the first side pressure applying means constituted by the first and second magnetic bodies is provided on one bearing side, and the second side pressure applying means having the same configuration as the first side pressure applying means is provided on the other side. It is preferably provided on the bearing side.

Further, in the compact motor of the present invention having a preferable structure, the rotating shaft is rotatable by a pair of arc segment-shaped permanent magnets for rotation mounted on the inner peripheral surface of the casing and a bearing device mounted on the casing. A rotor that is supported by the rotor and that is arranged to face the rotating permanent magnet, and that is mounted on the output side of the rotating shaft and is disposed inside the casing and that has a diameter substantially the same as the core of the rotor. A disk made of iron in which a plurality of openings are formed in a plate-like portion which is thicker in the axial direction all around the outer peripheral edge and thinner inward than the outer peripheral edge, and a cylindrical inner peripheral surface with respect to this disk. Are opposed to each other through a minute gap and are attached to the inner peripheral surface of the casing,
An arc segment-shaped permanent pressure applying permanent magnet for pulling the disk outward in a constant radial direction by a magnetic force is provided.

The miniature motor of the present invention is a miniature motor mounted on a frame of a disc reproducing apparatus,
A turntable on which a disc is placed is preferably attached to the output part of the rotary shaft.

[Function] A minute clearance is secured between the inner peripheral surface of the bearing and the outer peripheral surface of the rotary shaft. Even if the rotary shaft that makes a rotary motion tries to axially vibrate in the radial direction because of the clearance, the second magnetic body pulls the first magnetic body outward in the constant radial direction by the magnetic force, and the side pressure is applied to the rotary shaft. Therefore, the rotary shaft is pulled to the second magnetic body side and keeps in contact with a fixed place on the inner peripheral surface of the radial bearing. Therefore, the rotary shaft continues the rotary motion smoothly without vibrating.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. (First Embodiment) FIGS. 1 to 19 are views for explaining a first embodiment of the present invention. FIG. 1 is a front sectional view of a small motor of the present invention, and FIG. 2 is a line II-II of FIG. A sectional view and FIG. 3 are external perspective views of the small motor of FIG.

As shown in FIGS. 1 and 3, the small motor 1 of this embodiment is a direct drive type motor for directly rotating an optical disk 2 such as a CD as a disk, and the small motor 1 is a brush. It shows the case of a DC motor with a switch. The small motor 1 is mounted on a disc reproducing device such as a CD player. For convenience of explanation, the following description will be given with the direction of the rotary shaft output portion where the disc 2 is located as the upward direction.

The small motor 1 has an inner peripheral surface 4 of the casing 3.
The rotary shaft 7 is rotatably supported by the bearing device 6 mounted on the casing 3, and the rotor 8 faces the stator 5. The casing 3 is formed of a metal material such as a cold rolled steel plate made of mild steel into a hollow cylinder having a bottom and a surface of which is galvanized, and an opening 1 of the housing 9.
It has a disk-shaped bottom plate member 11 formed of the same material as the housing 9.

The housing 9 is integrally formed by press molding or the like, and the circular upper plate 12 is fixed to the frame 13 of the disc reproducing apparatus.
The stator 5 is fixed to the cylindrical inner peripheral surface 4 of the housing 9 and is composed of a pair of rotating permanent magnets 5 formed in an arc segment shape by a magnetic material such as hard ferrite.

The rotor 8 has a rotating shaft 7 extending in the direction of a central axis C, which is the center of rotation, and an armature winding 14 mounted on the rotating shaft 7 and wound around a core 15 in a coil shape to form a permanent magnet 5.
The armature 16 is provided with a rotational force by the above, and a commutator 17 that is assembled into a cylindrical shape and attached to the rotating shaft 7 and that is electrically connected to the armature 16. The rotating shaft 7 is preferably made of a stainless material so that the surface thereof is always smooth and the clearance between the rotating shaft 7 and the radial bearings 31 and 34 described later is small.
The armature 16 has a predetermined size (for example, about 0.
2 mm) and is arranged inward of the gap.

A cylindrical commutator support member 18 is fixed to the rotating shaft 7, and the commutator 17 is fitted on the outer peripheral surface 18a of the commutator support member 18. The commutator 17 is fixed to predetermined positions in the axial direction and the circumferential direction by an annular washer 19 which is press-fitted onto the outer peripheral surface of the commutator. Commutator 17
An oil stop washer 20 is fixed to the rotary shaft 7 at the lower end of the shaft to prevent the oil in the bearing from flowing toward the commutator 17.

On the bottom plate member 11, a plurality of sets (for example, two sets) of brushes 21 made of a conductor material are provided with a commutator 17.
Is provided for sliding engagement with. A plurality of (for example, two) connection terminals 22 electrically connected to each brush 21 are attached to the bottom plate member 11 via a brush holder 23 made of an insulating material such as synthetic resin.

A cylindrical protrusion 30 is formed in the central portion of the housing upper plate 12 by drawing, and the protrusion 3
The upper radial bearing 31 of the bearing device 6 is press-fitted and fixed to the inner peripheral surface of 0. The upper radial bearing 31 rotatably supports the output portion 32 side of the rotary shaft 7 and supports it in the radial direction.

A circular bottomed recess 33 is integrally formed in the central portion of the bottom plate member 11 by drawing. A lower radial bearing 34 is press-fitted and fixed to the inner peripheral surface of the bottomed recess 33, and a lower end portion 35 of the rotary shaft 7 is fixed to the lower radial bearing 3.
4 is rotatably and axially supported in the radial direction. The radial bearings 31 and 34 may be formed of plastic or a general metal material. However, the radial bearings 31 and 34 are formed of iron-copper-based powder-sintered metal or powder-sintered alloy impregnated with lubricating oil. It is preferable because it has good lubricity and is maintenance-free.

A disk-shaped thrust bearing 36 formed of a steel plate or plastic is fixed to the bottom of the bottomed recess 33, and the lower end 35 of the rotary shaft is rotatably abutted on the thrust bearing 36. . As a result, the rotary shaft 7 is supported by the thrust bearing 36 in the thrust direction.
As the thrust bearing 36, it is preferable to use a lubricative plastic from the viewpoint of reducing the frictional resistance with the rotating shaft 7, preventing wear, and preventing noise. In this way, the bearing device 6
Includes an upper radial bearing 31, a lower radial bearing 34, and a thrust bearing 36, and rotatably supports the rotary shaft 7.

A turntable 37 is fixed to the output section 32 of the rotary shaft 7, and the optical disk 2 is placed on the turntable 37. The central position D ₂ of the magnetic force of the rotating permanent magnet 5 is set to the central position D ₁ of the magnetic force of the armature 16.
It is located slightly below. Due to the downward magnetic attraction force and the gravity due to the rotary motion part including the rotor 8, the turntable 37, and the disk 2 mounted on the turntable 37, the rotor 8 is always pulled downward. There is. This pulling force is applied to the thrust bearing 3
It is supported by 6 and prevents the rotary motion part from vibrating in the vertical direction.

As shown in FIGS. 1 and 2, the casing 3
A first magnetic body 41 attached to the rotating shaft 7 and a second magnetic body 42 attached to the inner peripheral surface of the casing facing the first magnetic body 41 are provided in the interior 40 of the casing. ing.
The second magnetic body 42 pulls the first magnetic body 41 outward in the radial direction (in the direction of arrow H) by a magnetic force to rotate the rotary shaft 7.
The side pressure is applied to the first and second magnetic bodies 4
The first lateral pressure applying means 43 is constituted by 1, 42. The first lateral pressure applying means 43 is arranged close to the upper radial bearing 31 as one bearing.

As the first magnetic body, a disc 41 made of a magnetic material such as iron is used, and the outer diameter of the disc 41 is made substantially the same as the outer diameter of the core 15, so that a strong lateral pressure can be obtained. It is preferable in terms. As the second magnetic body, an arc segment-shaped lateral pressure applying permanent magnet 42 attached to the casing inner peripheral surface 4 is used. This permanent magnet 4
The cylindrical inner peripheral surface 44 of 2 is opposed to the disk 41 via the minute gap G, and the disk 41 is pulled outward by a magnetic force in a constant radial direction (direction of arrow H), and a sufficiently large lateral pressure is applied to the rotating shaft 7. I am trying to give.

By the way, a permanent magnet 5 for rotation, which is optimum for reducing the characteristics of the cogging torque to smoothly rotate the rotor 8, and a permanent permanent magnet for adding side pressure, which has a strong magnetic force optimum for generating sufficient lateral pressure. Since the material and shape of the magnet 42 may be different from each other, it is preferable that the permanent magnets 5 and 42 are separately attached to the casing inner peripheral surface 4 as in the present embodiment. The size of the gap G is disc 4
Considering the manufacturing error and the mounting error of 1 and the permanent magnet 42, about 0.2 mm is the preferable minimum value.

The fan-shaped spread angle θ of the permanent magnet 42 is preferably, for example, about 30 ° to about 180 °, but particularly about 45 ° to about 90 °, because a large lateral pressure can be effectively applied to the rotary shaft 7. Is preferred. In this embodiment, θ = about 60 ° is shown as the optimum angle in that the lateral pressure can be increased.

A hollow cylindrical bush 46 is provided on the upper surface 45 of the disk 41, and the bush 46 is fixed to the rotating shaft 7 and is not in contact with the upper radial bearing 31. The bush 46 restricts the movement of the rotor 8 toward the output section 32.

In the small motor 1 having such a structure, when a current is passed from the connection terminal 22 to the armature winding 14 via the brush 21 and the commutator 17, the magnetic field formed by the pair of rotating permanent magnets 5 is generated. Rotor 8 inside
A rotational force is applied to the rotor 8, and the rotor 8 makes a rotational motion. As a result, the rotary shaft 7 and the turntable 37 rotate,
CD, LD, CD- mounted on the turntable 37
The optical disc 2 such as a ROM or MD rotates, and the optical pickup device 47 reads and reproduces the information recorded on the disc 2.

When the rotary shaft 7 rotates, the disk 41 also makes a rotary motion inside the side pressure-applying permanent magnet 42 while maintaining a predetermined gap G. If a magnet having a strong magnetic force is used as the permanent magnet 42 for adding lateral pressure and the gap G is made minute, the disk 41 has a strong pulling force due to the magnetic force, and is indicated by an arrow H.
Since it is always pulled in the direction, a sufficient amount of lateral pressure can be applied to the rotating shaft 7.

FIG. 4 is an enlarged partial cross-sectional view showing the state of the rotary shaft 7 of FIG. As shown in FIGS. 1 and 2, although there is a minute clearance E between the upper radial bearing 31 and the rotary shaft 7, the disk 41 is the permanent magnet 4 for adding side pressure.
2 is always pulled in the direction of arrow H. Therefore, in a state where lateral pressure is applied to the rotary shaft 7 so that the rotary shaft 7 is always attracted in the direction of the arrow H, the rotary motion is performed while being in contact with the inner peripheral surface 31a on the right side in the figure in the upper radial bearing 31,
The central axis C of the rotary shaft 7 has also moved slightly to the right in FIG.

By the way, since the disk 41 and the permanent magnet 42 for adding lateral pressure are arranged close to the output portion 32 of the rotary shaft 7, the rotary shaft 7 at the position of the upper radial bearing 31.
Although the lateral pressure on the rotary shaft 7 is large, the lateral pressure is small on the lower end portion 35 side of the rotating shaft 7. Therefore, at the position of the lower radial bearing 34, in the state where the lower radial bearing 34 moves in the direction opposite to the arrow H in terms of the overall balance of the rotary motion part including the rotor 8, the disk 41, the turntable 37 and the disk 2 which rotate. The rotary shaft 7 makes a rotary motion in the lower radial bearing 34.

As described above, the first position is provided near the disc 2.
Since the lateral pressure applying means 43 is provided to apply a sufficiently large lateral pressure to the rotary shaft 7, it is possible to reliably prevent the shaft vibration of the rotary shaft 7 even when the total mass of the rotary motion portion is large. Even if the clearance E in the upper radial bearing 31 is about several micrometers (for example, 5 μm), the rotary shaft 7 does not vibrate, so the disk 2 hardly vibrates in the radial direction. Therefore, the vibration of a disc such as a CD is affected by the pitch of the track (for example, about 1.6).
.mu.m) or less, the optical pickup device 47 can accurately read the information on the disc 2, and a reproduction error unlike the conventional case does not occur.

Further, since the first side pressure applying means 43 is provided inside the casing 3 rather than outside the motor, when the small motor 1 is attached to the frame 13 of the disc reproducing apparatus, the side pressure applying means 43 interferes with the attachment. Never be. When the rotating shaft 7 is made of stainless steel, the magnetic force acting on the rotating shaft 7 is small, but the disk 41 made of iron attached to the rotating shaft 7 is used.
Since a strong magnetic force acts on the rotary shaft 7, sufficient lateral pressure can be applied to the rotary shaft 7 via the disc 41.

Further, in the case of the conventional motor which mechanically applies the lateral pressure by using the spring, the lateral pressure is reduced due to the generation of mechanical noise and abrasion, but according to the present invention, the magnetic force is used to non-contact. Since the lateral pressure is applied to the rotary shaft 7, no mechanical noise or wear occurs and the lateral pressure does not decrease.

5 to 8 are views for explaining the principle of the present invention. FIG. 5 is a plan view of the lateral pressure applying means 43 of the present invention.
6 is a vertical cross-sectional view of FIG. 5, FIG. 7 is a plan view of the rotary shaft pulled by magnetic force, and FIG. 8 is a vertical cross-sectional view of FIG. 7.

As shown in FIGS. 5 and 6, in this embodiment, the permanent magnet 42 for adding side pressure, which faces the outer peripheral edge portion 48 of the disk 41, has an arc spread at an angle of 60 ° with respect to the central axis C. It has a segment shape. For example, when the outer diameter of the disc 41 is 12 mm and the thickness thereof is 3 mm, the facing area S ₁ between the permanent magnet 42 and the disc 41 is calculated by the following equation (1). S ₁ = 12 × π × 3 × 60 ° / 360 ° = 18.85 mm ² ……… (1)

On the other hand, as shown in FIGS. 7 and 8, the rotary shaft 5 having the same dimensions as the rotary shaft 7 and made of a magnetic material such as iron.
Consider a case where 0 is attracted by an arc segment-shaped permanent magnet 51 having a spread angle of 60 °. This configuration is similar to the configuration in the above-mentioned publication in which the lateral pressure is applied to the rotary shaft in the conventional motor. For example, the diameter of the rotating shaft 50 is 1.5 mm, and the thickness of the permanent magnet 51 is the disk 41 of FIG.
If 3 mm is used, the rotary shaft 50 and the permanent magnet 51
The facing area S ₂ with respect to is calculated by the following equation (2). S ₂ = 1.5 × π × 3 × 60 ° / 360 ° = 2.36 mm ² ……… (2)

Such arc segment-shaped permanent magnet 51
Even if the spread angle is set to 180 ° which is the maximum limit angle at which the magnetic attraction force is effectively generated, the facing area S ₂ is given by the following expression (3). S ₂ = 1.5 × π × 3 × 180 ° / 360 ° = 7.07 mm ² ……… (3)

It can be seen that in both cases, the facing area S ₂ is extremely smaller than the facing area S ₁ in the present invention. As described above, according to the lateral pressure applying means 43 of the present invention, the facing area S ₁ can be made larger than in the conventional case, so that the rotary shaft 7 can be pulled together with the disc 41 by a strong magnetic force, and a sufficient lateral pressure can be applied. Can be given to.

According to an experiment conducted by the present inventor, when the spread angles of the permanent magnets 42 and 51 are 60 ° as shown in FIGS. 5 to 8 and the gap G is equal, the lateral pressure of the conventional structure is P. _{While 2} = 5 gf, the lateral pressure according to the present invention was P ₁ = 46 gf, which was a large value. As described above, according to the present invention, an extremely large lateral pressure can be obtained as compared with the conventional method in which the rotary shaft is attracted by magnetic force.

9 to 18 are views showing a modified example of the disk of the present invention, FIG. 9 is a plan view of the modified example of the disk, and FIG. 10 is FIG.
FIG. The first magnetic body is the outer peripheral edge portion 48a.
It is preferable that the entire circumference is thick in the axial direction and the inner plate-like portion 52 is thin, and that the plate-like portion 52 has a circular shape as a whole because a strong magnetic force can be obtained and the mass can be reduced. Therefore, as shown in the figure, the length L ₁ of the outer peripheral edge portion 48a of the disk 41a as the first magnetic body in the direction of the central axis C is increased to thicken the entire outer peripheral edge portion 48a, and Thickness L of plate portion 52
₂ is thinly formed. The entire disc 41a is integrally molded.

The outer peripheral edge portion 48a is formed to have a predetermined thickness because the tensile force of the magnetic force increases as the thickness T ₁ of the outer peripheral portion 48a increases to some extent. The larger the length L ₁ of the outer peripheral edge portion 48a is, the larger the tensile force due to the magnetic force is. Therefore, the optimum dimension is determined in relation to the axial length of the lateral pressure applying permanent magnet 42. Since the plate-like portion 52 does not affect the tensile force due to the magnetic force, the plate thickness L ₂ of this portion is thin.

By constructing the disc 41a in this way, the pulling force of the permanent magnet 42 for adding side pressure can be increased, and the weight of the disc 41a itself can be reduced to reduce the moment of inertia. Also,
Since the hollow portion formed by thinning the plate-shaped portion 52 becomes a space 54, by disposing the bush 46 and a part of the armature 16 in this space portion 54, for example, the entire motor length of the small motor 1 ( The size of the motor can be reduced by shortening the axial dimension).

FIG. 11 is an elevational sectional view showing another modified example of the disk, and its plane shape is the same as that of FIG. The disc 41b as the first magnetic body is formed by integrally bending a plate member by press molding or the like, and the entire outer peripheral edge portion 48b is thickened in the axial direction (length). L ₁ ).
By doing so, the thickness L ₂ of the plate-shaped portion 52b becomes relatively smaller than the length L ₁ of the outer peripheral edge portion 48b, and the same operational effect as that of the disc 41a is obtained. Further, the disc 41b can be easily manufactured by press molding or the like.

FIG. 12 is an elevational sectional view showing another modification of the disk, and the shape of the plane is the same as that of FIG. The disc 41c as the first magnetic body has a configuration in which two discs 41b of FIG. 11 are attached back to back. The entire outer peripheral edge portion 48c is thick in the axial direction, and the plate-like portion 52c on the inner side thereof is thick.
Has a thin circular shape. This is preferable because the length L ₁ of the outer peripheral edge portion 48c can be increased and the tensile force due to the magnetic force increases.

FIG. 13 is a plan view showing another modified example of the disk.
FIG. 14 is an elevational sectional view of FIG. As shown,
A plurality of circular openings 53 are formed in the plate-like portion 52d that is inside the outer peripheral edge portion 48d of the disc 41d as the first magnetic body. By doing so, the weight of the disc 41d itself is significantly reduced, and the moment of inertia can be reduced. The shape of the opening 53 is not limited to a circular shape, but a circular shape is preferable from the viewpoint of ease of forming work. Further, it is preferable from the viewpoint of overall balance that the plurality of openings 53 having the same shape are evenly arranged in the circumferential direction, and in this embodiment, four circular openings 53 are equally arranged in the circumferential direction by 90 °. ing.

By the way, there are cases where control is performed to change the rotation speed of a small motor, but in order to change the rotation speed quickly, it is necessary to reduce the weight of the rotary motion part including the rotor to reduce the moment of inertia. is there. Therefore, if the plate-shaped portion of the disc is thinned or the opening 53 is formed as described above, the weight of the disc is reduced, the moment of inertia is reduced, and the rotation speed can be changed quickly. Also, the efficiency of the motor is improved.

FIG. 15 is a plan view showing another modification of the disc.
FIG. 16 is an elevation sectional view of FIG. The disc 41e as the first magnetic body has a configuration in which the disc 41a and the disc 41d are combined. That is, the entire circumference of the outer peripheral edge portion 48e is thick in the axial direction, and the inner plate-shaped portion 52e is thin,
It has a circular shape as a whole, and moreover, a plurality of openings 53 are formed in the plate-like portion 52e and are evenly arranged in the circumferential direction. In this way, a strong tensile force due to the magnetic force can be obtained, and the weight can be reduced to reduce the moment of inertia, and the total length of the motor can be shortened to reduce the thickness.

FIG. 17 is a plan view showing another modification of the disk,
FIG. 18 is a sectional view taken along line XVIII-XVIII in FIG. As shown in the figure, the disk 41f serving as the first magnetic body has an outer peripheral edge portion 48 larger than the opening 53 of the disk 41e.
A fan-shaped wide opening 53f is formed so as to follow f. The entire outer peripheral edge portion 48f is thick in the axial direction and the plate portion 52f is thin. As a result, the disc 41f
The weight of is further reduced, the moment of inertia is reduced, and the total length of the motor can be shortened to make the motor thinner.

FIG. 19 shows a second unit attached to the casing 3.
FIG. 8 is a partial elevational cross-sectional view of a small motor showing a modification of the magnetic body of FIG. When the rotating permanent magnet and the lateral pressure applying permanent magnet have the same optimum material, shape, and the like, as shown in the drawing, two arc segment-shaped rotating permanent magnets 5 are provided on the stator.
5a are used to face each other, and one of the rotating permanent magnets 5a is integrally extended in parallel with the direction of the central axis C to form an extending portion 60, and the extending portion 60 serves as a second magnetic body. This eliminates the need to separately prepare the second magnetic body, reduces the number of parts, and facilitates the assembly of the motor.

(Second Embodiment) FIG. 20 is an external perspective view of a small motor showing a second embodiment of the present invention, and FIG. 21 is a plan sectional view of the small motor of FIG. Small motor 1 of this embodiment
a, a pair of parallel flat portions 61 are formed on both sides of the housing 9a, and a pair of arc segment-shaped permanent magnets 5 as a stator are formed on the cylindrical inner peripheral surface 4a.
Although b is attached, the other structure is the same as that of the first embodiment. By forming the flat portion 61, the width dimension of the motor can be reduced, and the installation space of the motor 1a in the disc reproducing device or the like can be reduced.

(Third Embodiment) FIG. 22 is a front sectional view of a small motor showing a third embodiment of the present invention. As shown in the figure, in the small-sized motor 1b of the present embodiment, the first lateral pressure applying means 43 constituted by the first magnetic body 41 and the second magnetic body 42 is provided in the same manner as in the first embodiment. It is provided on the side of the upper radial bearing 31 which is the bearing. Also, the first
The second lateral pressure applying means 43a having the same configuration as the lateral pressure applying means 43 is provided on the side of the lower radial bearing 34 which is the other bearing.

That is, the side pressure-applying permanent magnet 42a, which is the second magnetic body, is disposed below the rotating permanent magnet 5 and attached to the casing inner peripheral surface 4. Further, the lateral pressure applying permanent magnets 42, 42a are arranged 180 ° apart from each other. A disk 41g made of iron or the like, which is a first magnetic body, is attached to the rotary shaft 7 so as to face the permanent magnet 42a. Although the disc 41g is fixed to the outer peripheral surface of the commutator support member 18 in this embodiment, it may be directly attached to the rotary shaft 7.

According to this embodiment, the output unit 32 of the rotary shaft 7
On the side, side pressure is applied in the direction of arrow H by the first side pressure application means 43, and on the side of the lower end portion 35 of the rotary shaft 7, the direction opposite to the arrow H is indicated by the second side pressure application means 43a. Lateral pressure is applied in the H ₁ direction). As a result, the pulling force on the lower end 35 side of the rotating shaft is increased, and the shaft vibration can be prevented even better.

The side pressure applying permanent magnet 42a of the second side pressure applying means 43a does not necessarily have to be provided on the opposite side of the first side pressure applying means 43 away from the permanent magnet 42 by 180 °, and the housing 9 It may be attached at any position in the circumferential direction of.

FIG. 23 is a partial front sectional view showing a modification of the second magnetic body mounted on the casing 3 side in the small motor shown in FIG. If the rotating permanent magnet and the lateral pressure applying permanent magnet have the same optimum material and shape,
As shown in the figure, the stator is formed by two arc segment-shaped permanent magnets 5a and 5c for rotation, and the permanent magnets 5a and 5c are integrally extended in parallel with the central axis C direction to form an extension portion 60. The extension portion 60 is a permanent magnet for adding lateral pressure as the second magnetic body of the first and second lateral pressure applying means 43, 43a. By doing so, it is not necessary to provide separate second magnetic bodies to the first and second lateral pressure imparting means 43 and 43a, respectively, so that the number of parts is reduced and the assembly is facilitated.

In the first to third embodiments, the motor is used in the vertical type, that is, the output portion 32 side of the rotary shaft 7 is directed upward, but the portable type disc is portable. The playback apparatus is often used in a posture other than the vertical type, and the present invention can be applied to small motors used in various postures. When used in various postures as described above, the magnetic forces of the first and second magnetic bodies are made sufficiently large so that the side pressure that overcomes the weight of the rotary motion part including the rotor etc. 7 is preferable.

In addition to the DC motor with a brush as described above, the present invention can be applied to other small motors such as a brushless motor, a stepping motor and an AC motor. The disk rotated by the small motor may be an optical disk, a magnetic disk such as an FD (flexible disk) or a hard disk, or another disk. In each of the above-described embodiments, the first magnetic body is a disk made of iron and the second magnetic body is a permanent magnet. However, the first magnetic body may be formed of a permanent magnet. In this case, the second magnetic body may be a magnetic material such as iron or a permanent magnet. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0067]

Since the small motor according to the present invention is configured as described above, it is possible to surely prevent the shaft vibration of the rotating shaft by giving a sufficient side pressure to the rotating shaft.

[Brief description of drawings]

1 to 19 are views for explaining a first embodiment of the present invention, and FIG. 1 is a front sectional view of a small motor of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

3 is an external perspective view of the small motor of FIG. 1. FIG.

FIG. 4 is a partial cross-sectional view showing an enlarged state of a rotary shaft in FIG.

5 to 8 are views for explaining the principle of the present invention, and FIG. 5 is a plan view of a lateral pressure applying means of the present invention.

FIG. 6 is a sectional elevation view of FIG.

FIG. 7 is a plan view when a rotating shaft is pulled by magnetic force.

FIG. 8 is a sectional elevation view of FIG.

9 to 18 are views showing a modified example of the disk of the present invention, and FIG. 9 is a plan view of the modified example of the disk.

10 is a sectional elevation view of FIG.

FIG. 11 is an elevational sectional view showing another modified example of the disk.

FIG. 12 is an elevation sectional view showing another modified example of the disk.

FIG. 13 is a plan view showing another modified example of the disk.

14 is a sectional elevation view of FIG.

FIG. 15 is a plan view showing another modified example of the disk.

16 is a sectional elevation view of FIG.

FIG. 17 is a plan view showing another modification of the disc.

18 is a sectional view taken along line XVIII-XVIII in FIG.

FIG. 19 is a partial elevational sectional view of a small motor showing a modified example of the second magnetic body attached to the casing.

FIG. 20 is an external perspective view of a small motor showing a second embodiment of the present invention.

FIG. 21 is a plan sectional view of the small motor shown in FIG. 20.

FIG. 22 is a front sectional view of a small motor showing a third embodiment of the present invention.

FIG. 23 is a partial front cross-sectional view showing a modified example of the second magnetic body in the small motor of FIG. 22.

[Explanation of symbols]

 1, 1a, 1b Small motor 2 Optical disk 3 Casing 4, 4a Inner peripheral surface 5, 5a to 5c Rotating permanent magnet (stator) 6 Bearing device 7 Rotating shaft 8 Rotor 13 Frame 15 Core 31 Upper part Radial bearing (one bearing) 32 Output section 34 Lower radial bearing (other bearing) 37 Turntable 40 Inner casing 41, 41a to 41g Disk (first magnetic body) 42, 42a Side pressure applying permanent magnet (second) 43) First lateral pressure applying means 43a Second lateral pressure applying means 44 Cylindrical inner peripheral surface 48, 48a to 48f Outer peripheral edge portion 52, 52b to 52f Plate portion 53, 53f Opening portion 60 Extension portion ( Second magnetic material) C Central axis G Gap

Claims (7)

[Claims] 1. An inner peripheral surface (4, 4a) of a casing (3)
A rotor (8) that is rotatably supported by a stator (5, 5a to 5c) attached to the casing and a bearing device (6) attached to the casing so that the rotating shaft (7) faces the stator. A small motor having a rotary shaft attached to the inside of the casing (4
0) the first magnetic body (41, 41a to 41)
g) and a second magnetic body (42, 42a, 42a, 42a, 42a, 42a, 42a, 60)
And a small motor. 2. The first magnetic body has an outer peripheral edge portion (48,
48a to 48f) The small motor according to claim 1, wherein the entire circumference is thick in the axial direction, and the plate-like portions (52, 52b to 52f) on the inner side are thin, and the overall shape is circular. 3. The small motor according to claim 1 or 2, wherein a plurality of openings (53, 53f) are formed in a plate-like portion inside the outer peripheral edge portion of the first magnetic body. 4. The stator is formed of two arc segment-shaped permanent magnets for rotation (5a to 5c), and the permanent magnets for rotation are integrally extended in parallel with the central axis (C) direction and extended. The small motor according to any one of claims 1 to 3, wherein the extension portion (60) is formed, and the extension portion is formed of the second magnetic body. 5. A first lateral pressure imparting means (43) composed of the first and second magnetic bodies is provided on one bearing (31) side, and has a configuration similar to that of the first lateral pressure imparting means. The small motor according to any one of claims 1 to 4, wherein the second lateral pressure applying means (43a) is provided on the other bearing (34) side. 6. A rotating shaft is rotatably supported by a pair of arc segment-shaped rotating permanent magnets mounted on the inner peripheral surface of the casing, and a bearing device mounted on the casing so that the rotating permanent magnets are supported by the rotating permanent magnets. A rotor disposed opposite to the rotor, mounted on the output part (32) side of the rotary shaft and disposed inside the casing, and having a diameter substantially the same as the core (15) of the rotor, and an outer peripheral edge A disk made of iron having a plurality of openings formed in a plate-like portion whose inner circumference is thick in the axial direction and which is thinner inward than the outer peripheral edge, and a cylindrical inner peripheral surface (44) with respect to the disk. And an arc segment-shaped permanent magnet for applying a lateral pressure, which is opposed to each other via a minute gap (G), is attached to the inner peripheral surface of the casing, and pulls the disk outward in the constant radial direction by a magnetic force. A small motor that does. 7. A small motor mounted on a frame (13) of a disc reproducing apparatus, wherein a turntable (37) for mounting a disc (2) is mounted on an output part (32) of the rotary shaft (7). The small motor according to any one of claims 1 to 6, wherein the small motor is provided.