JP3633949B2 - Micro motor - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a micromotor suitable for OA equipment such as CD-ROM, AV equipment, in-vehicle electrical equipment, and the like.
[0002]
[Prior art]
A conventional micromotor is configured, for example, as shown in FIG. That is, a shaft e is rotatably supported through bearing bearings c and d on a covered cylindrical metallic case a and a bush b provided in a lid shape on the lower surface opening of the case a. An annular rotor magnet f is fixed to the inner periphery 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 periphery of the rotor magnet f, and 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 integrally.
[0003]
[Problems to be solved by the invention]
In such a conventional structure, the resin spacer i is filled between the shaft e and the rotor magnet f in order to integrate the shaft e and the rotor magnet f, but the configuration is complicated. In addition, manufacturing and assembly were very difficult and there was a problem in terms of cost. In addition, since the amount of filling of the spacer i between the shaft e and the rotor magnet f is large, the rotor portion becomes very heavy, smooth start-up of the micromotor or stable high-speed rotation cannot be obtained, and power consumption increases. There's a problem.
[0004]
The present invention has been made in consideration of such problems of the prior art, and an object of the present invention is to provide a micromotor that has a simple structure and can easily start a rotor. is there.
[0005]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, a micromotor according to the present invention has a rotatable shaft disposed in the axial center portion of an annular stator, and an inner diameter thereof is arranged in a circumferential direction larger than an outer diameter of the shaft. In a micromotor in which a cylindrical rotor magnet is fixed using a fixing means, the fixing means includes an outer cylinder portion having an outer diameter slightly larger than the inner diameter of the rotor magnet, and an inner diameter substantially equal to the outer diameter of the shaft. The formed inner cylinder part, an annular connecting plate connecting the outer cylinder part and the inner cylinder part, and a plurality of radial slits extending from a part of the outer cylinder part through the connecting plate to the entire inner cylinder part. The outer cylinder part is press-fitted inside the rotor magnet, and the inner cylinder part is elastically pressed against the shaft .
[0006]
In this case, it is desirable that the fixing means is disposed at both ends of the rotor magnet, and the annular back yoke disposed inside the rotor magnet is sandwiched between the both fixing means.
[0007]
[Action]
In the micro motor of the present invention described above, in order to integrate the shaft and the rotor magnet, the outer cylinder part and the inner cylinder part, and the annular connecting plate for connecting the outer cylinder part and the inner cylinder part are provided. Use fixing means. The fixing means is provided with a plurality of radial slits through the inner cylinder part, the connecting plate and the outer cylinder part, and with the shaft inserted inside the inner cylinder part, the outer cylinder part is arranged inside the rotor magnet. When press-fitted, the outer cylinder part is deformed inwardly, the fixing means is securely fixed inside the rotor magnet, and the inner cylinder part is also inwardly contracted 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 integrated and fixed via the fixing means.
[0008]
【Example】
Hereinafter, the present invention will be described based on illustrated embodiments.
[0009]
FIG. 1 shows the overall configuration of an embodiment of a micromotor according to the present invention, and FIG. 2 shows fixing means.
[0010]
In FIG. 1, the lower surface opening of the covered cylindrical metallic case 1 is covered with a disc-shaped bush 2 made of resin or metal such as Duracon, and inside the bearing holder 3 fitted in the center of the bush 2. A shaft 6 is rotatably supported via bearings 4 and 5 held respectively at the center of the lid portion of the case 1.
[0011]
Inside the peripheral wall of the case 1, a single-phase coil 8 that is single-winded or concentratedly wound around an annular coil bobbin 7 is disposed, and its thickness-to-height ratio in the radial direction is lowered. Therefore, a rotor magnet having a large radius and height can be used, and the shaft torque can be increased. An upper magnetic pole plate 9 and a lower magnetic pole plate 10 are disposed on the upper and lower surfaces of the coil bobbin 7, respectively. The coil bobbin 7 is made of, for example, a resin such as Duracon, and is divided into two parts. The upper and lower magnetic pole plates 9 and 10 are made of a pressed material made of a silicon steel plate containing pure iron containing about 1 to 2% silicon (Si).
[0012]
On the inner circumference of the upper and lower magnetic pole plates 9 and 10, a plurality of upper and lower magnetic pole teeth 11 and 12 positioned inside the coil bobbin 7 are formed by bending, for example, respectively. The lower magnetic poles 12 and 12 are alternately arranged along the inner peripheral surface of the coil bobbin 7 to constitute a stator magnetic pole. An annular stator 26 is constituted by those indicated by reference numerals 7 to 12.
[0013]
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, the upper magnetic pole teeth 11, and the lower magnetic pole plates 12 are magnetized. Accordingly, an attractive force and a repulsive force act on both the magnetic poles of the rotor magnet, which will be described later, facing the surfaces of the upper and lower magnetic pole teeth 11 and 12, and a rotational force is generated in the rotor magnet.
[0014]
A cylindrical yoke 13 is disposed 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 silicon steel plate and is longer in the axial direction than the coil bobbin 7. The upright molds 4, 15 formed on the outer peripheral portions of the upper and lower magnetic pole plates 9, 10 are yokes. 13 are in contact with the inner surfaces of the upper and lower end portions and are magnetically connected.
[0015]
An annular rotor magnet 17 in which a back yoke 16 is press-fitted and fixed in an annular shape on the inner periphery and an N pole and an S pole are alternately arranged on the outer periphery is integrally provided on the shaft 6 by a fixing means 18. .
[0016]
A circuit board 19 is disposed on the bottom of the case 1, that is, on the upper surface of the bush 2, and the coil 8 is connected to a terminal portion of the circuit board 19, and the magnetic field of the rotor magnet 16 is detected on the circuit board 19. A sensor 20 such as a Hall element and a driving IC (not shown) are attached.
[0017]
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.
[0018]
As shown in FIGS. 1 and 2 (a) and 2 (b), the fixing means 18 has an outer portion having a flange portion 22a formed with an outer diameter slightly larger than the inner diameter of the rotor magnet 17 and projecting outward at the upper end. A cylindrical portion 22, an inner cylindrical portion 23 having an inner diameter substantially equal to the outer diameter of the shaft 6, and an annular connecting plate 24 that connects the outer cylindrical portion 22 and the inner cylindrical portion 23, are provided. A plurality of radial slits 25 extending from a part (for example, all except the flange portion 22a) to the entire inner cylinder portion 23 through the connecting plate 24 are formed. The fixing means 18 can be easily formed only by pressing a flat plate.
[0019]
Then, with the shaft 6 having an outer diameter substantially equal to the inner diameter of the inner cylindrical portion 23 inserted into the inner cylindrical portion 23, the outer cylindrical portion 22 having an outer diameter formed slightly larger than the inner diameter of the rotor magnet 17, When the inner portion of the rotor magnet 17 is press-fitted, the outer cylindrical portion 22 is elastically contracted inward using the elasticity formed in the cylindrical portion of the outer cylindrical portion 22 by the plurality of slits 25, and at the same time, the inner portion passes through the connecting plate 24. An inward contracting force is generated in the cylindrical portion 23. Therefore, the inner cylinder portion 23 is elastically pressed against the shaft 6 inserted inside the inner cylinder portion 23, and the shaft 6 is fixed in the inner cylinder portion 23. As a result, the rotor magnet 17 is securely fixed to the shaft 6 via the fixing means 18.
[0020]
The fixing means 18 is disposed at both ends of the rotor magnet 17, that is, above and below the shaft 6, respectively.
[0021]
Further, an annular back yoke 16 is disposed inside the rotor magnet 17 and is sandwiched between both fixing means 18 disposed at both ends of the rotor magnet 17 so as to be fixed for the back yoke 16. This back yoke 16 can be reliably fixed inside the rotor magnet 17 without requiring any means.
[0022]
As mentioned above, although the Example of the micromotor according to this invention was described, this invention is not limited to this Example, A various change is possible without deviating from the scope of the present invention.
[0023]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained. An outer cylinder part having an outer shape 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 enter the inner cylinder part 23. Since the shaft 6 is fixed 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 6 is inserted into the inner cylinder portion 23. In this state, a simple operation of press-fitting the outer cylinder portion 22 into the rotor magnet 17 is sufficient, the assembly is simplified, and the cost including the material cost can be reduced as compared with the conventional case. In addition, since the rotor magnet 17 can be fixed to the shaft 6 only by the fixing means 18, the entire rotor can be reduced in weight, the start-up can be facilitated, and the power consumption can be greatly reduced.
[0024]
Further, if the annular back yoke 16 disposed inside the rotor magnet 17 is sandwiched between the fixing means 18 disposed at both ends of the rotor magnet 17, means for fixing the back yoke 16 is provided. The back yoke 16 can be reliably fixed to the rotor magnet 17 without any particular requirement.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a micromotor of the present invention.
2 shows the fixing means of FIG. 1, wherein (a) is a front view and (b) is a plan view. FIG.
FIG. 3 is a cross-sectional view of a micromotor showing a conventional example.
[Explanation of symbols]
6 Shaft 16 Back yoke 17 Rotor magnet 18 Fixing means 22 Outer cylinder part 23 Inner cylinder part 24 Connecting plate 25 Slit 26 Stator

Claims (3)

A rotatable shaft is disposed at the axial center of the annular stator, and a cylindrical rotor magnet having an inner diameter larger than the outer diameter of the shaft and alternately arranged in the circumferential direction is fixed to the shaft. In a micromotor that is fixed by
The fixing means includes an outer cylinder part having an outer diameter slightly larger than an inner diameter of the rotor magnet, an inner cylinder part having an inner diameter substantially equal to the outer diameter of the shaft, the outer cylinder part, and the inner cylinder. An annular connecting plate connecting the parts, and a plurality of radial slits from a part of the outer cylinder part through the connecting plate to the entire inner cylinder part,
The micro motor according to claim 1, wherein the outer cylinder portion is press-fitted inside the rotor magnet, and the inner cylinder portion presses the shaft with elasticity . The micromotor according to claim 1, wherein the fixing means is disposed at both ends of the rotor magnet. The micro motor according to claim 2, wherein an annular back yoke is disposed inside the rotor magnet, and the back yoke is sandwiched between fixing means respectively disposed at both ends of the rotor magnet.

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