JPH06253516A - Miniature motor - Google Patents

Abstract

PURPOSE:To facilitate manufacture by forming a permanent magnet of a sheet- like flexible rare earth bond magnet and to increase the saturation magnetic flux density by allowing magnetization of unit body. CONSTITUTION:DC pulse current is applied to a magnetization coil 16 with a sheet member 17 being mounted on a lower magnetization yoke 15 to create a parallel field between the magnetization yokes 15 thus magnetizing the sheet member 17 in the direction of thickness. When the sheet member 17 is built in a case 1, the sheet member 17 deforms arcuately to be brought into tight contact with the inner face of the case 1. Since a permanent magnet having deformed sheet member 17 produces flux in the radial direction, effective amount of flux interlinking an armature in the case 1 increases thus enhancing the output from a miniature motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to audio equipment, video equipment,
The present invention relates to a small motor used for precision equipment and the like, and more particularly to a small motor improved so as to obtain a high output by increasing the amount of magnetic flux generated by a permanent magnet as a constituent member.

[0002]

2. Description of the Related Art FIG. 1 is a vertical sectional front view of an essential portion showing an example of a small motor which is the subject of the present invention. In FIG. 1, reference numeral 1 denotes a case, which is formed of a metallic material such as soft iron into a hollow cylindrical shape with a bottom, and has an inner peripheral surface to which a permanent magnet 2 formed in, for example, an arc segment shape is fixed. A rotor 5 including an armature 3 facing the permanent magnet 2 and a commutator 4 can be provided in the case 1. Next, 6 is a case cap, which is made of, for example, synthetic resin or other insulating material so as to be fitted into the opening of the case 1. A brush arm 7 is provided so as to be slidably engaged with the commutator 4, and is provided on the case cap 6 together with an input terminal 8 electrically connected to the brush arm 7. Reference numerals 9 and 10 denote bearings, which are fixed to the bottom portion of the case 1 and the central portion of the case cap 6, respectively, and rotatably support the shaft 11 constituting the rotor 5.

With the above structure, the current is supplied from the input terminal 8 to the armature 3 via the brush arm 7 and the commutator 4 forming the rotor 5, so that the case 1 is fixed to the inner peripheral surface of the case 1. The rotating force is applied to the armature 3 existing in the magnetic field formed by the generated permanent magnet 2, and the rotor 5
Can be rotated, and an external device (not shown) can be driven via the output side shaft 11.

[0004]

In the small motor having the above structure, the permanent magnet 2 fixed to the inner peripheral surface of the case 1 is used.
Is formed of a sheet material containing, for example, rare earth magnet material powder and rubber as main components. Such a structure has an advantage that the permanent magnet 2 can be easily incorporated into the case 1 in a small motor having a small diameter of the case 1, but has a magnetizing means for the permanent magnet 2. Complex or permanent magnet 2
There is a problem that the amount of magnetic flux generated from is insufficient and it is difficult to improve motor characteristics.

First, FIG. 2 is a partial sectional explanatory view showing means for magnetizing the case 1 from the outer surface thereof. In FIG. 2, reference numeral 21 denotes a magnetizing yoke around which a magnetizing coil 22 is wound, and is a sheet material mainly composed of a rare earth magnet material powder and rubber on the inner peripheral surface between the pair of magnetizing yokes 21, 21. With the case 1 to which 23 is fixed positioned, a solid cylindrical inner yoke 24 is interposed in the sheet material 23, and a DC pulse voltage is applied to the magnetizing coil 22 to magnetize the sheet material 23. Of.

However, in the magnetizing means as shown in FIG. 2, since the magnetic field acting on the sheet material 23 is a parallel magnetic field between the magnetizing yokes 21, 21, the sheet material 23 becomes a permanent magnet after magnetization. The magnetic flux generated from the magnetic field is also parallel, and the amount of magnetic flux effectively acting on the armature 3 shown in FIG. 1 is not sufficient. Therefore, there is a problem that the high performance possessed by the rare earth rubber magnet cannot be utilized.

Next, FIG. 3 is a sectional view showing a means for magnetizing the inside of the case 1. In FIG. 3, reference numeral 25 is a magnetizing yoke, which is formed in a solid columnar shape and is provided with a recess 26 in which a magnetizing coil 27 is embedded. Then, for example, a DC pulse voltage is applied to the magnetizing coil 27,
The sheet material 23 fixed in the case 1 is magnetized.

The magnetizing means shown in FIG. 3 has the advantage that the sheet material 23 can be magnetized substantially in the radial direction, and can be magnetized more strongly than by the parallel magnetic field. However, in order to saturate the sheet material 23, it is necessary to apply a large current of 1,600 kA / m or more to the magnetizing coil 27. On the other hand, the magnetizing coil 27 is a magnetizing yoke 25.
Since it is embedded in the narrow recess 26 provided in
The case 1 having a large inner diameter is exceptional, for example, in the case of a small motor having an inner diameter of 25 mm or less, the magnetizing coil 27 generates heat when a large current as described above is applied, And will be transformed,
It has a short life and is difficult to apply for mass production.

The present invention solves the above problems existing in the prior art, is easy to manufacture, and generates high magnetic flux.
The object is to provide a small motor with high output.

[0010]

In order to achieve the above object, in the present invention, a case formed of a metal material in a hollow cylindrical shape with a bottom and a permanent magnet fixed to the inner peripheral surface thereof, A rotor including an armature facing the magnet and a commutator, a brush fitted in the opening of the case and slidably engaged with the commutator, and an input terminal electrically connected to the brush. In a small motor comprising a case cap provided with, and rotatably supporting the rotor through a bearing provided on the bottom of the case and the case cap, a permanent magnet is provided via a parallel magnetic field. It is formed by a plurality of flexible sheet rare earth bond magnets magnetized in the thickness direction, and is fixed to the inner surface of the case so that NS magnetic poles appear alternately on the inner surface in the circumferential direction. Technical means to do It was adopted.

In the present invention, the magnetic powder forming the flexible rare earth-based bonded magnet is, for example, Sm-Co-based, N-based.
An intermetallic compound (RM) of a rare earth metal (R) and a transition metal (M) can be used like the d-Fe-B type, but an Nd-Fe-B type having a large magnetic energy product is used. preferable.

On the other hand, as the binding material of the magnetic powder, rubber-based materials such as natural rubber, neoprene rubber, nitrile rubber, butyl rubber, polyisobutylene, and chlorinated polyethylene can be used, and as long as it has flexibility. , Plastic materials can be used.

As the means for producing the above-mentioned rare earth-based bonded magnet, not only extrusion molding and roll rolling but also compression molding and injection molding using a molding die may be used.
Further, a magnetic field molding means for carrying out the molding operation in a magnetic field can also be used.

[0014]

With the above construction, the magnetic flux acting on the armature provided opposite to the permanent magnet made of the sheet-like flexible rare earth-based bonded magnet is in a substantially radial direction, and is interlinked with the armature. The amount of magnetic flux generated increases, and the output of the small motor can be improved.

[0015]

EXAMPLE FIG. 4 is a partial cross-sectional explanatory view showing a magnetizing means for a sheet material in an example of the present invention. In FIG. 4, 1
Reference numeral 5 denotes a magnetizing yoke around which a magnetizing coil 16 is wound. The magnetizing yoke 5 is made of a ferromagnetic material such as soft iron, and a pair of upper and lower parts are arranged to face each other with an appropriate gap. Reference numeral 17 denotes a sheet material, which is formed into a sheet shape by using, for example, a material containing Nd-Fe-B based magnet material powder and neoprene rubber as main components.

In FIG. 4, for example, a DC pulse current is applied to the magnetizing coil 16 with the sheet material 17 placed on the lower magnetizing yoke 15 to form a parallel magnetic field between the magnetizing yokes 15, 15. It is created and the sheet material 17 is magnetized in the thickness direction. FIG. 5 is an enlarged end view showing the sheet material 17 magnetized by the magnetizing means shown in FIG. 4, and the arrow indicates the magnetizing direction.

FIG. 6 is an end view of an essential part showing a state where the magnetized sheet material 17 is incorporated in the case 1. In this case, the width dimension of the sheet material 17 in the direction perpendicular to the magnetizing direction is set to a dimension corresponding to 1/2 of the length of the inner circumference of the case 1, and
It is formed so that N and S magnetic poles appear in the circumferential direction. 18
Is an abutting portion of the two sheet materials 17, 17 and is formed so as to be in close contact with each other without forming a gap.

As is apparent from FIG. 6, when the sheet material 17 is incorporated into the case 1, the sheet material 17 is deformed into an arc shape and closely fixed to the inner peripheral surface of the case 1. In this case, an adhesive may be interposed between the sheet material 17 and the case 1. It can be seen that the sheet material 17 is deformed as described above, so that the magnetization direction becomes the radial direction.
Since the magnetic flux generated from the permanent magnet formed by the sheet material 17 being deformed and fixed in this manner is naturally in the radial direction, the magnetic flux is generated with respect to the armature (see reference numeral 3 in FIG. 1) interposed in the case 1. As a result, the amount of effective magnetic flux interlinking with each other is increased, and the output of the small motor can be improved.

FIG. 7 is an enlarged end view showing a state of being magnetized by the magnetizing means shown in FIG. 2, and the same portions are designated by the same reference numerals as those in FIG. That is, the sheet material 23 formed of the same material as the sheet material 17 in FIG.
Is formed to have a size corresponding to the length of the inner circumference of the case 1, and is assembled into the case 1 through the butting portion 28 and then magnetized. Therefore, the magnetizing directions of the sheet material 23 are parallel as indicated by the arrow. Therefore, the effective magnetic flux amount interlinking with the armature 3 shown in FIG.
It will be smaller than that shown in.

Table 1 shows the results of measuring the magnetic flux of the permanent magnet formed by the magnetizing mode shown in FIGS. 6 and 7 for a small motor having the same specifications. The amount of magnetic flux in the table is the sheet material 17 in FIG. 6 and FIG.
23 shows the value in the state of being magnetized to the saturation magnetization. The magnetizing means is according to the present invention shown in FIG. 4 and the comparative example is shown in FIG. 2, and the permanent magnets are magnetized in the directions shown in FIGS. It is in the state shown in. As the sheet materials 17 and 23 forming the permanent magnet, Nd-Fe-B type materials having a maximum magnetic energy product of 48 kJ / m ³ were used.

[0021]

[Table 1]

As is apparent from Table 1, the magnetic flux amount of the present invention is increased by 10% or more than that of the comparative example. FIG. 8 is a diagram showing the relationship between the magnetizing magnetic field and the amount of magnetic flux, which is the result of measurement for the motor (b) shown in Table 1. In FIG. 8, curves a and b respectively correspond to those of the present invention and those of the comparative example. As is clear from FIG.
In a region where the magnitude of the magnetizing magnetic field is small, the curve b of the comparative example has a larger amount of magnetic flux, but in a region where the magnetizing magnetic field is large, the curve of the present invention is used. The magnetic flux amount is larger in a. That is, it can be seen that the present invention has a larger saturation magnetic flux amount.

FIG. 9 is a diagram showing the relationship between the angle in the circumferential direction and the surface magnetic flux density, which is the result of measurement for the motor (b) shown in Table 1. In FIG. 9, curves a and b respectively correspond to those of the present invention and those of the comparative example, as in FIG. As is clear from FIG. 9, the curve a of the present invention has a wider range of higher surface magnetic flux density than the curve b of the comparative example. Since the amount of magnetic flux is proportional to the area surrounded by the curve, it is clear that the present invention has a larger output, and therefore the output as a small motor is also larger in the present invention.

In the present invention, the example in which the permanent magnet 2 is formed by the two sheet materials 17, 17 has been described. However, the permanent magnet 2 is formed by four or more sheet materials and is alternately arranged on the inner circumferential surface in the circumferential direction. Of course, it may be fixed to the inner peripheral surface of the case 1 so that the magnetic pole appears.

[0025]

EFFECTS OF THE INVENTION Since the present invention has the structure and operation as described above, the following effects can be obtained. (1) Since the permanent magnet is formed of a sheet-shaped flexible rare earth-based bonded magnet, it is easy to manufacture, and it can be magnetized as a single unit, and the saturation magnetic flux density can be increased. (2) A sheet-shaped flexible rare earth bonded magnet magnetized by a parallel magnetic field is fixed to the inner peripheral surface of the case to obtain a permanent magnet in a substantially radially magnetized state, and as a result, a magnetic flux interlinking with the armature. The amount is increased, and a small motor with high output can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional front view of essential parts showing an example of a small-sized motor which is an object of the present invention.

FIG. 2 is a partial cross-sectional explanatory view showing means for magnetizing from the outer surface of the case 1.

FIG. 3 is a cross-sectional view showing a means for magnetizing from the inner surface of the case 1.

FIG. 4 is a partial cross-sectional explanatory view showing a magnetizing means for a sheet material in the embodiment of the present invention.

5 is an enlarged end view showing the sheet material 17 magnetized by the magnetizing means shown in FIG.

FIG. 6 is an enlarged end view showing a state where the magnetized sheet material 17 is incorporated into the case 1.

7 is an enlarged end view showing a state of being magnetized by the magnetizing means shown in FIG.

FIG. 8 is a diagram showing a relationship between a magnetizing magnetic field and a magnetic flux amount.

FIG. 9 is a diagram showing a relationship between a circumferential angle and a surface magnetic flux density.

[Explanation of symbols]

 1 Case 2 Permanent magnet 17 Sheet material

Claims (1)

[Claims] 1. A case (1) formed of a metallic material in the shape of a hollow cylinder with a bottom and having a permanent magnet (2) fixed to its inner peripheral surface, and an armature (3) facing the permanent magnet (2). )
And a commutator (4), a brush fitted in the opening of the case (1) and slidably engaged with the commutator (4), and electrically connected to the brush. A case cap (6) provided with an input terminal (8) connected to it
In the small motor, the rotor (5) is rotatably supported via bearings (9) and (10) provided on the bottom of the case (1) and the case cap (6). The permanent magnet (2) is formed by a plurality of sheet-like flexible rare earth-based bonded magnets magnetized in the thickness direction via a parallel magnetic field, and NS magnetic poles are alternately arranged on the inner circumferential surface in the circumferential direction. A small motor which is fixed to the inner peripheral surface of the case (1) so that