JPH02246755A - Electric motor - Google Patents

Abstract

PURPOSE:To reduce eddy current by molding a stator from a composite material, in which a matrix such as resin is mixed with a plurality of magnetic particles. CONSTITUTION:A stator 13 is molded into a hollow disc from a composite material, in which thermoplastic resin as matrix is mixed with a plurality of magnetic particles 14, and swelling isosceles triangular cores 13a with vertexes directed to the shaft center are formed at equal spaces circumferentially on one plane. Said particles 14 are formed long and narrow from, e.g. malleable iron. In this case, magnetic field is applied axially to the stator 13 so that the longitudinally direction of each particle 14 coincides with the axial direction. Thus, eddy current generated in the stator 13 can be suppressed between the particles 14 and controlled to a small value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electric motor in which a stator is provided facing a flat surface of a disk-shaped rotor.

BACKGROUND ART As this type of electric motor, for example, an axial gap type electric motor as shown in FIG. 5 is known. This electric motor includes a disc-shaped rotor l in which different magnetic poles are arranged alternately in the circumferential direction on a flat part 1a, and this rotor 1.
The stator 2 is provided with a thin plate-shaped stator 2 facing the flat part 1a of the rotor l, and the stator 2 has a plurality of cores 2a for winding the coils 3 facing the flat part 1a of the rotor l. It is prominent. In addition, the code|symbol 4 is a housing which covers the rotor l, the stator 2, etc.

The electric motor configured as described above has a disc-shaped rotor 1 and a thin plate-shaped stator 2 facing each other, so that the electric motor itself can be formed thin.

However, when the stator 2 is integrally formed from a material such as iron, the magnetic field passing through the stator 2 changes due to the rotation of the rotor l, and this generates eddy currents within the stator 2, so that the electric motor The disadvantage is that the efficiency of the method decreases. However, the stator 5 used in a normal electric motor as shown in FIG. 6 has iron plates 6 layered in the axial direction to prevent the generation of eddy currents. Since the direction of the magnetic field is different, the stator 5 cannot be applied as is.

For this reason, stators molded using Fe-3i powder metallurgy, for example, have been developed as stators that can suppress the generation of eddy currents to some extent.

[Problem to be solved by the invention] However, when forming the stator using the above powder metallurgy,
There is a problem that sintering after compression molding takes a lot of effort and time, and the dimensions change considerably due to sintering.

For this reason, it has been desired to develop an electric motor having a stator that reduces eddy currents and can be easily molded.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a stator made of a composite material in which a plurality of magnetic particles are mixed in a matrix of resin or the like.

[Function] In the present invention, a stator in which a plurality of particles are uniformly distributed can be molded using, for example, an injection molding machine. Thus, a stator with excellent dimensional accuracy can be provided simply and in a short time. Since magnetic particles are uniformly distributed within the stator,
By passing current through the coils, a magnetic field can be generated in the stator. Furthermore, even if the magnetic field emitted from the rotor and passing through the stator changes due to the rotation of the rotor, the eddy current generated in the stator can be blocked between particles, and the generation of the eddy current can be prevented. Can be kept extremely small.

Furthermore, as the above-mentioned particles, Fe and Fe-8i metal powders are basically used, but M nZ nF eto 4
Of course, soft magnetic material powder such as ferrite powder such as 1N iZ nF eto 4 may also be used.

[Embodiment] Hereinafter, an embodiment in which the present invention is applied to an axial gap type electric motor will be described in detail with reference to FIGS. 1 to 4. However, elements common to those shown in FIG. 7 are denoted by the same reference numerals, and the explanation thereof will be simplified.

In FIG. 3, ■ is a rotor formed into a disk shape, and an output shaft 11 is connected to the axis of the rotor l. The output shaft 11 is rotatably supported by a housing 12.12 provided so as to sandwich and cover the rotor l from both sides.

Each housing 12 has a recess 12a arranged annularly around the output shaft 11 on the surface facing the flat part 1a of the rotor l, and a stator 1 is provided in the recess 12a.
3 is fixed with adhesive or bolts.

As shown in FIGS. 1 and 2, the stator 13 is made of a composite material in which a plurality of magnetic particles 14 are mixed into a thermoplastic resin as a matrix, and is formed into a hollow disk shape. On one plane, isosceles triangular cores 13a bulging out with their apexes directed toward the axis are formed at equal intervals in the circumferential direction. The particles 14 are made of pure iron and formed into elongated shapes, and the length thereof is 0.01ia+~
It is formed to 5.00I1m. Here, the length of the particle 14 is set to 0. (111II11 to 5.0001111 was chosen because manufacturing would be difficult if it was less than 0.01 mm, and if it was 5,00 ml or more, for example, when molding with an injection molding machine, the screw for kneading the composite material, etc.) This is because failures such as severe wear and particles 14 clogging the gate through which the resin passes may occur.

The stator 13 is produced by injecting the composite material into a cavity C in the shape of the stator I3, which is created by closing the fixed mold 1 and the movable mold 2, as shown in FIG. A magnetic field is applied in the axial direction of the stator 13 to align the longitudinal direction of each particle 14 with the axial direction.

Further, in FIGS. 1 and 3, reference numeral 3 indicates a fill wound around the core 13a of the stator 13.

In the electric motor configured as described above, by sequentially passing current through each coil 3, the core 13a formed in the stator 13 is sequentially excited, and thereby the rotor 1
rotates. At this time, since the particles 14 are made of pure iron and have an extremely high magnetic permeability, and the elongated direction of the particles 14 is aligned with the axial direction, the core 13
A large magnetic force is generated in the axial direction, that is, in the direction perpendicular to the plane portion 1a of the rotor 1. Furthermore, when the rotor 1 rotates, the magnetic field emitted from the rotor 1 and passing through the stator 13 changes, which causes eddy currents to occur within the stator 13. will be blocked.

In the electric motor configured as described above, by passing current through the coil 3, the core 13 of the stator 13 is
Since it is possible to generate a large magnetic force in the axial direction at a, and to suppress the generation of eddy currents to an extremely low level, the efficiency of the electric motor can be extremely high.

Moreover, since the stator 13 is made of a composite material in which a plurality of particles 14 are mixed with resin, the stator 13 can be molded using, for example, an injection molding machine.

Therefore, even if the core 13a has a complicated shape such that it bulges, it can be manufactured easily and in a short time with excellent dimensional accuracy.

In the above embodiment, the particles 14 are formed into elongated shapes, but they may be formed into spherical or flat shapes.

In addition, although the particles 14 were made of pure iron, silicon steel (Fe-3
i series) as well as M nZ nF e, 04+
It may be formed of ferrite such as N iZ nF e,o or other magnetic materials.

Further, although the stator 13 is fixed to the housing 12 with an adhesive or the like, it may be fixed to the housing 12 during molding by inserting the housing 12 into the mold.

[Effects of the Invention] As explained above, according to the present invention, the stator is molded from a composite material in which a plurality of magnetic particles are mixed in a matrix of resin, etc. , the stator can be molded. Therefore, a stator with excellent dimensional accuracy can be formed easily and in a short time. Furthermore, since the eddy current that exists within the stator can be blocked between particles, the eddy current can be kept extremely small.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 to 4 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a cross-sectional view taken along line 1-1 in FIG. 3, and FIG. 1 is a sectional view taken along the line ■-■, FIG. 3 is a sectional view of the electric motor, FIG. 4 is an explanatory diagram showing a stator manufacturing method, and FIG. 5 is an exploded perspective view of the electric motor shown as a conventional example. FIG. 6 is a perspective view of an ordinary electric motor shown as another conventional example. Fig. 1 Fig. 2 1... Rotor, la... Plane part, 3.
... Coil, 13 ... Stator, 13a
...Core, 14...Particle.

Claims (1)

[Claims] In an electric motor having a disc-shaped rotor in which different magnetic poles are alternately arranged in the circumferential direction on a flat part, and a stator provided facing the flat part of the rotor, the stator is formed in a matrix of resin or the like. An electric motor characterized in that it is molded from a composite material in which a plurality of magnetic particles are mixed.