JPS6237423Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a permanent magnet DC motor using permanent magnets as field magnetic poles.

Conventionally, in a DC motor, it was not possible to fix magnetic pole pieces made of magnetic material to the inner surface of a cylindrical ferrite magnet to concentrate magnetic flux in the air gap.
It is publicly known as described in Japanese Patent No. 7792.
Due to the manufacturing method, cylindrical ferrite magnets are limited to isotropic magnetic materials (magnetic flux density of about 2 kilogauss).
We use ferrite magnets with a bow-shaped cross section that can be made from anisotropic magnetic material (magnetic flux density of about 3.5 kilogauss).
By constricting the magnetic flux with magnetic pole pieces, something with extremely high performance can be obtained. Furthermore, since surface loss occurs on the inner surface of the magnetic pole piece when the magnetic pole piece is made of a mild steel ingot, it is also known to use a magnetic pole piece in which a large number of magnetic pole pieces are laminated in the axial direction. However, in conventional laminated magnetic pole pieces, magnetic bolts or rivets were inserted into the fastening holes provided in these and fastened in the axial direction of the DC motor. However, the disadvantage was that the armature reaction was large. especially,
In devices such as servo motors, which accelerate and decelerate by passing large currents, the decrease in response due to armature reaction cannot be ignored, and improving performance by using magnetic pole pieces can reduce the increase in armature reaction. This resulted in a practical difficulty.

The object of this invention is to provide a permanent magnet DC motor that can eliminate the above-mentioned drawbacks of the conventional motor by using bolts or rivets made of non-magnetic material to fasten the laminated magnetic pole pieces in the axial direction.

Hereinafter, embodiments of this invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of this invention. In the figure, 1 is a cylindrical yoke made of a magnetic material, 2 is a magnet made of anisotropic ferrite magnetic material and has a bow-shaped cross section (arc shape), and the magnet 2 has a number of poles on the inner surface of the yoke 1. In the case of the one in FIG. 1, a number equal to 4) are closely fixed at equal intervals. Reference numeral 3 denotes a magnetic pole piece in which mild steel plates or silicon steel plates are laminated in the axial direction of the DC motor, and the magnetic pole piece 3 is closely fixed to the inner surface of the magnet 2. 4 is a plurality of fastening holes formed in the magnetic pole piece 3 by punching, 6 is an armature core that rotates together with the shaft 5, 7 is an armature slot provided in the armature core 6, and 8 is an armature slot. These are the armature coils housed in the armature 7, and the armature 9 is constituted by these.
10 is a gap formed between the outer surface of the armature core 6 and the inner surface of the magnetic pole piece 3. 11 is a non-magnetic bolt inserted into the fastening hole 4; one bolt 11;
One magnetic pole piece 3 is fastened in the axial direction to prevent it from coming apart. The shape of the magnetic pole piece 3 is
The area facing the air gap 10 is smaller than the area facing the magnet 2, and as can be seen from the main magnetic flux Φm shown in FIG. A high magnetic flux density is obtained in the air gap 10.

Next, the operation of this embodiment will be explained. When a current flows through the armature coil 8, the first
Armature reaction magnetic flux is generated in the direction shown by Φr in the figure, but since the non-magnetic bolt 11 passes through the magnetic pole piece 3, the path of the armature reaction magnetic flux Φr becomes narrower, increasing the magnetic resistance. . Therefore, the armature reaction is suppressed to be smaller than that using magnetic bolts.

Although the above embodiment describes the case of a four-pole ferrite magnet, this invention can also be applied to magnets with other numbers of poles and other magnet materials, and the same effects as in the above embodiment can be obtained in these cases as well.

Moreover, FIGS. 2A, B, and C show other embodiments of this invention. In FIG. 2A, a part of the fastening hole 4 is opened on the inner surface of the magnetic pole piece 3 to further increase the magnetic resistance to the armature reaction magnetic flux Φr. Second
In Figure B, the fastening hole 4 is a square hole, and a bolt 11 having a square cross section is used, so that the bolt 11 can be easily prevented from rotating when fastened. In FIG. 2C, a part of the fastening hole 4 is opened on the outer surface of the magnetic pole piece 3,
This increases the magnetic resistance to the armature reaction magnetic flux Φr. Note that the opening of the fastening hole 4 in FIG. 2C is closed by the magnet 2. In addition, the shape and number of the fastening holes 4 of this invention can be changed as appropriate, rivets may be used in place of the bolts 11, and the shape of the bolts or rivets can be modified in various ways.

As explained above, according to this invention, a magnetic pole piece made of laminated magnetic plates is attached to the inner surface of the magnet, and the area where the magnetic pole piece faces the air gap with the armature is made smaller than the area where the magnetic pole piece faces the magnet. In the formed one, a fastening hole is provided in the magnetic pole piece, a bolt or rivet made of a non-magnetic material is inserted into the fastening hole,
Since the magnetic pole pieces are fastened in the axial direction of the DC motor, armature reaction can be reduced, and a high-performance permanent magnet type DC motor can be provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a permanent magnet type DC motor according to one embodiment of this invention, and FIGS. 2A, B, and C are partial cross-sectional views showing main parts of other mutually different embodiments of this invention. It is. 1... Yoke, 2... Magnet, 3... Magnetic pole piece, 4...
... fastening hole, 5 ... shaft, 6 ... armature core, 7 ... armature slot, 8 ... armature coil, 9 ... armature, 10 ... gap, 11 ... bolt. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] (1) A magnetic pole piece 3 made of laminated magnetic plates is attached to the inner surface of the magnet 2, and the air gap 10 between the magnetic pole piece 3 and the armature 9 is larger than the area where the magnetic pole piece 3 faces the magnet 2. In a permanent magnet DC motor having a small area facing the magnetic pole piece 3, a fastening hole 4 is provided in the magnetic pole piece 3, a bolt 11 or a rivet made of a non-magnetic material is inserted into the fastening hole 4, and the magnetic pole piece 3 is connected to the DC motor. A permanent magnet DC motor characterized by being fastened in the axial direction. (2) The permanent magnet DC motor according to claim 1, in which the magnet 2 is made of an anisotropic ferrite magnetic material having an arcuate cross section. (3) A permanent magnet DC motor according to claim 1 or 2 of the utility model registration claim, in which a bolt 11 or a rivet with a square cross section is inserted into the fastening hole 4, which is a square hole.