JPH07212996A - Micromotor - Google Patents

Abstract

PURPOSE:To simply integrate and assemble a shaft and a rotor magnet by anchoring an outer cylinder whose outside diameter is slightly larger than the inside diameter of the rotor magnet and an inner cylinder whose inside diameter is almost equal to the outside diameter of the shaft to each other using ring- shaped coupling plates, and forming a plurality of slits in a radial pattern between the outer and inner cylinders. CONSTITUTION:The outside diameter of an outer cylinder is slightly larger than the inside diameter of a rotor magnet 17. The inside diameter of an inner cylinder is almost equal to the outside diameter of a shaft 6. The outer and inner cylinders are anchored to each other using anchoring means 18 composed of ring-shaped coupling plates. A plurality of slits are formed in a radial pattern at an equal anglar interval between the outer and inner cylinders to form a rotor, which is supported between bearings 4, 5 in a way that it is freely rotatable. A single-phase coil 8 is formed on a ring-shaped coil bobbin 7, and is placed on the inside surface of a cylindrical metal case 1 to obtain a stator with a reduced size in the radial direction. Magnetic pole plates 9, 10 are placed on the top and bottom surfaces of the coil bobbin 7. This facilitates the assembly of a micromotor and reduces the cost therefor.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an OA such as a CD-ROM.
The present invention relates to a micromotor suitable for equipment, AV equipment, in-vehicle electrical equipment, and the like.

[0002]

2. Description of the Related Art A conventional micromotor is constructed, for example, as shown in FIG. That is, a shaft e is rotatably supported by a cylindrical metallic case a with a lid and a bush b provided in a lid-like shape at the lower surface opening of the case a via bearings c and d, respectively. An annular rotor magnet f is fixed to the inner peripheral surface of the case a, and an annular stator g is disposed on the inner peripheral surface of the case a so as to face the rotor magnet f. An annular back yoke h is press-fitted and fixed to the inner circumference of the rotor magnet f, a spacer i made of resin such as Duracon is filled between the back yoke h and the shaft e, and the rotor magnet f is connected to the shaft e. It is configured to rotate as a unit.

[0003]

In such a conventional structure, in order to integrate the shaft e and the rotor magnet f, a resin spacer i is filled between the shaft e and the rotor magnet f. However, the structure is complicated, manufacturing and assembling are very difficult, and there is a cost problem. In addition, since the amount of the spacer i between the shaft e and the rotor magnet f is large, the rotor portion becomes very heavy, smooth start of the micromotor or stable high-speed rotation cannot be obtained, and power consumption also increases. There's a problem.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a micromotor having a simple structure and easy starting of a rotor. To do.

[0005]

In order to achieve the above-mentioned object, a micromotor according to the present invention has a rotatable shaft arranged at an axial center portion of an annular stator, the inner diameter of which is outside of the shaft. In a micromotor in which cylindrical rotor magnets arranged in a circumferential direction larger than a diameter are fixed by using fixing means, the fixing means includes an outer cylinder portion whose outer diameter is slightly larger than the inner diameter of the rotor magnet, An inner cylinder part whose inner diameter is formed to be approximately equal to the outer diameter of the shaft, an annular connecting plate which connects the outer cylinder part and the inner cylinder part, and a part of the outer cylinder part to the entire inner cylinder part through the connecting plate. And a plurality of radial slits extending therethrough, the outer cylinder portion is press-fitted inside the rotor magnet, and the shaft is press-fitted inside the inner cylinder portion.

In this case, it is desirable that the fixing means be arranged at both ends of the rotor magnet, and that the annular back yoke arranged inside the rotor magnet be sandwiched by both fixing means.

[0007]

In the above-described micromotor of the present invention,
In order to integrate the shaft and the rotor magnet, a fixing means having an outer tubular portion, an inner tubular portion, and an annular connecting plate that connects the outer tubular portion and the inner tubular portion is used. The fixing means includes
A plurality of radial slits are provided through the inner cylinder part, the connecting plate, and the outer cylinder part, and when the outer cylinder part is press-fitted inside the rotor magnet with the shaft inserted inside the inner cylinder part, the outer cylinder part Contracts and deforms inwardly, the fixing means is securely fixed to the inside of the rotor magnet, and the inner cylindrical portion also contracts inwardly via the connecting plate. As a result, the shaft is completely fixed to the contracted inner cylinder portion, so that the shaft and the rotor magnet are integrally fixed by the fixing means.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments.

FIG. 1 shows the overall construction of an embodiment of a micromotor according to the present invention, and FIG. 2 shows a fixing means.

In FIG. 1, a lower surface opening of a metallic case 1 having a cylindrical shape with a lid is covered with a disk-shaped bush 2 made of a resin such as Duracon or a metal, and a bearing holder fitted in the central portion of the bush 2. A shaft 6 is rotatably supported via bearings 4 and 5 which are held in the inside of the casing 3 and in the center of the lid of the case 1.

Inside the peripheral wall of the case 1, there is provided a single-phase coil 8 which is wound around an annular coil bobbin 7 in a single winding, that is, concentrated winding, and its thickness-to-height ratio in the radial direction is lowered. There is. Therefore, a rotor magnet having a large radius and a large height can be used, and the axial torque can be increased. An upper magnetic pole plate 9 and a lower magnetic pole plate 10 are arranged on the upper surface and the lower surface of the coil bobbin 7, respectively. The coil bobbin 7 is made of resin such as Duracon, and has a two-part configuration. Further, the upper and lower magnetic pole plates 9 and 10 are made of pure iron by about 1 to
% Of silicon (Si).

On the inner circumferences of the upper and lower magnetic pole plates 9 and 10, a plurality of upper and lower magnetic pole teeth 11 and 12 located inside the coil bobbin 7 are formed by bending, respectively, and the upper magnetic pole plate 9 has an upper magnetic pole 11 and a lower magnetic pole. The lower magnetic poles 12 of the plate 10 are alternately arranged along the inner peripheral surface of the coil bobbin 7 to form a stator magnetic pole. An annular stator 26 is constituted by those indicated by the reference numerals 7 to 12.

When the coil 8 is excited, a magnetic field is generated on the outer periphery of the coil 8, and the upper magnetic pole plate 9, the lower magnetic pole plate 10 or the upper magnetic pole teeth 11 and the lower magnetic pole plates 12 are magnetized. Therefore, an attractive force and a repulsive force act on both magnetic poles of the rotor magnet, which will be described later, that face the surfaces of the upper and lower magnetic pole teeth 11 and 12, and a rotational force is generated in the rotor magnet.

A cylindrical yoke 13 is arranged between the inner surface of the peripheral wall of the case 1 and the outer periphery of the coil bobbin 7.
The yoke 13 is made of a pressed material of a silicon steel plate and is formed to be longer than the coil bobbin 7 in the axial direction.
Vertical rise molds 4 and 15 formed on the outer peripheral portions of 10 are in contact with the inner surfaces of the upper and lower end portions of the yoke 13 and are magnetically connected.

An annular rotor magnet 17 in which an annular back yoke 16 is press-fitted and fixed to the inner circumference and N poles and S poles are alternately arranged on the outer circumference is integrally provided on the shaft 6 by fixing means 18. Has been.

A circuit board 19 is arranged on the bottom of the case 1, that is, on the upper surface of the bush 2. The coil 8 is connected to the terminal portion of the circuit board 19, and the magnetic field of the rotor magnet 16 is placed on the circuit board 19. A sensor 20 such as a Hall element for detecting the sensor and a driving IC (not shown) are attached.

A screw hole 21 for attaching the motor to an electronic device or the like is formed at an appropriate position on the outer periphery of the lid portion of the case 1.

The fixing means 18 is shown in FIGS. 1 and 2 (a),
As shown in (b), the outer cylindrical portion 22 has an outer diameter slightly larger than the inner diameter of the rotor magnet 17 and has a flange portion 22a protruding outward at the upper end, and the inner diameter is substantially equal to the outer diameter of the shaft 6. An inner cylinder portion 23 formed and an annular connecting plate 24 that connects the outer cylinder portion 22 and the inner cylinder portion 23 are provided, and a part of the outer cylinder portion 22 (for example, all except the collar portion 22a) is a connecting plate. Radial slits 2 extending through 24 to reach the entire inner cylindrical portion 23
A plurality of 5 are formed. The fixing means 18 can be easily formed only by pressing a flat plate.

Then, with the shaft 6 having an outer diameter substantially equal to the inner diameter of the inner tubular portion 23 inserted into the inner tubular portion 23,
When the outer cylinder portion 22 having an outer diameter slightly larger than the inner diameter of the rotor magnet 17 is press-fitted inside the rotor magnet 17, the elasticity formed in the cylindrical portion of the outer cylinder portion 22 by the plurality of slits 25 is utilized. As a result, the outer cylindrical portion 22 elastically contracts inward, and at the same time, an inward contracting force is generated in the inner cylindrical portion 23 via the connecting plate 24. Therefore, the inner tubular portion 23 elastically presses against the shaft 6 inserted inside the inner tubular portion 23, and the shaft 6 is press-fitted into the inner tubular portion 23. As a result, the rotor magnet 17 is securely fixed to the shaft 6 via the fixing means 18.

The fixing means 18 is the rotor magnet 1
7 are arranged at both ends, that is, above and below the shaft 6, respectively.

Inside the rotor magnet 17,
An annular back yoke 16 is arranged and sandwiched between both fixing means 18 arranged at both ends of the rotor magnet 17, so that the back yoke 16 is not particularly required. Can be securely fixed inside the rotor magnet 17.

Although the embodiment of the micromotor according to the present invention has been described above, the present invention is not limited to such an embodiment, and various modifications can be made without departing from the scope of the present invention.

[0023]

Since the present invention is constructed as described above, it has the following effects. The outer cylinder part having an outer diameter slightly larger than the inner diameter of the rotor magnet 17 is press-fitted into the rotor magnet 17, and the inner cylinder part 23 having an inner diameter substantially equal to the outer diameter of the shaft 6 is contracted inward to make the inner cylinder part 2
Since the shaft 6 is press-fitted into the shaft 3 and the rotor magnet 17 is fixed to the shaft 6, the shaft 6 and the rotor magnet 17 can be integrated with a simple structure, and the shaft can be housed in the inner cylindrical portion 23. With a simple operation of press-fitting the outer cylinder portion 22 into the rotor magnet 17 with 6 inserted, the assembly becomes simple and the material cost and the cost can be reduced as compared with the conventional case. Moreover, since the rotor magnet 17 can be fixed to the shaft 6 only by the fixing means 18, the weight of the entire rotor can be reduced, the starting thereof can be facilitated, and the power consumption can be greatly reduced.

If the annular back yoke 16 arranged inside the rotor magnet 17 is sandwiched between fixing means 18 arranged at both ends of the rotor magnet 17, the back yoke 16 is fixed. The back yoke 16 can be securely fixed to the rotor magnet 17 without particularly requiring the above means.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a micromotor of the present invention.

2 shows the fixing means of FIG. 1, (a) is a front view, (b)
Is a plan view.

FIG. 3 is a sectional view of a conventional micromotor.

[Explanation of symbols]

 6 Shaft 16 Back Yoke 17 Rotor Magnet 18 Fixing Means 22 Outer Cylinder 23 Inner Cylinder 24 Connecting Plate 25 Slit 26 Stator

Claims (3)

[Claims] 1. A cylindrical rotor magnet in which a rotatable shaft is arranged at an axial center of an annular stator, and an inner diameter is larger than an outer diameter of the shaft and different poles are alternately arranged in a circumferential direction on the shaft. In the micromotor in which the fixing means is fixed by using a fixing means, the fixing means is formed with an outer cylindrical portion having an outer diameter slightly larger than an inner diameter of the rotor magnet, and an inner diameter substantially equal to an outer diameter of the shaft. An inner tubular part, an annular connecting plate that connects the outer tubular part and the inner tubular part, and a plurality of radial slits extending from a part of the outer tubular part to the entire inner tubular part through the connecting plate. And the outer cylinder portion is press-fitted inside the rotor magnet,
A micromotor, wherein the shaft is press-fitted inside the inner tubular portion. 2. The micromotor according to claim 1, wherein the fixing means is arranged at both ends of the rotor magnet. 3. The micro yoke according to claim 2, wherein an annular back yoke is provided inside the rotor magnet, and the back yoke is sandwiched between fixing means arranged at both ends of the rotor magnet. motor.