JPH08163801A - motor - Google Patents

Abstract

(57) [Abstract] [Purpose] In a motor in which a field magnet is provided on either the stator or the rotor and an armature coil is provided on the other, the change in the magnetic field due to the interruption or interruption of the armature coil To reduce the eddy current induced in the field magnet. [Structure] Field magnet 1 provided on rotor 9
4 is divided into a plurality of parts in the axial direction, and a magnetic material plate member 16 coated with an insulating layer is provided between the divided magnets 15.
Insulate by. As a result, the passage of the eddy current flowing in the magnet 14 is narrowed, so that the eddy current can be made small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor in which a field magnet is provided on one of a stator and a rotor and an armature coil is provided on the other, and particularly, eddy current loss of the magnet is reduced. Regarding motors.

[0002]

2. Description of the Related Art For example, in a DC motor having a magnet type rotor, a cylindrical field magnet is attached to an outer peripheral portion of a rotor core, and a plurality of armature coils are attached to a stator. . Then, the rotor is rotated by sequentially controlling the on / off of the armature coil.

[0003]

The strength of the magnetic field of the armature coil changes depending on the current flowing through the armature coil, and the field magnet is indicated by an arrow A in FIG. 10 accordingly. Such an eddy current is induced. In particular, when the magnet is formed of neodymium-iron-boron-based material or samulium-cobalt-based material, the resistivity is as small as 0.00013 Ω · cm in the former and 0.00009 Ω · cm in the latter, so a large eddy current flows. However, the loss becomes non-negligible, resulting in problems such as a decrease in efficiency as a motor and heat generation of a magnet.

The present invention has been made in view of the above circumstances, and an object thereof is to reduce the eddy current induced in the field magnet by energization of the armature coil and reduce the power loss due to the eddy current loss. It is to provide a motor that can.

[0005]

In order to achieve the above object, the present invention provides, as a first means, a field magnet on one of a stator and a rotor and an armature coil on the other. In the motor, the magnet is divided into a plurality of pieces in a direction intersecting the direction in which the magnetic poles are arranged, and the divided magnets are insulated from each other.

In this case, the split magnets can be insulated from each other by an insulating layer coated on the split magnets, or by a magnetic plate material coated with the insulating layer. In order to further reduce the eddy current, a plurality of projections or recesses extending in the direction in which the magnetic poles are arranged are formed on the surface of the split magnet facing the armature coil in a direction intersecting the direction in which the magnetic poles are arranged. Is preferred.

In order to achieve the above object, according to the present invention, as a second means, a convex portion or a concave portion extending along the magnetic pole arranging direction on the surface of the magnet facing the armature coil is arranged in the magnetic pole arranging direction. It is characterized in that a plurality of them are formed in the intersecting direction.

[0008]

According to the first means, since the magnet is divided into a plurality of parts, the passage of the eddy current is narrowed and the electric resistance is increased. Therefore, it is possible to reduce the eddy current induced in the magnet due to the strength change of the magnetic field caused by the electric current passing through the armature coil, and to reduce the power loss due to the eddy current loss.

Further, according to the second means, considering that the eddy current flows to the surface layer, the protrusion or the recess is provided on the circumferential surface of the magnet, so that the passage of the eddy current is the protrusion or the recess. As a result, the eddy current induced in the magnet can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a radial gap type DC motor will be described below with reference to FIGS. In FIG. 1 showing the overall configuration of the motor, inside the motor case 3 consisting of a pair of divided cases 1 and 2,
A plurality of teeth 4a of a stator core 4 made of laminated steel plates are fitted with a stator 6 formed by winding an armature coil 5.

On the other hand, bearings 7 and 8 made of ball bearings are mounted at the centers of the end faces of the divided cases 1 and 2, and a shaft 10 of a rotor 9 is rotatably supported by the bearings 7 and 8. . A rotor body 12 is attached to the shaft 10 via a hub 11. The rotor body 12 has a magnet 14 attached to a bottomed cylindrical rotor yoke 13 made of a magnetic material such as iron. Consists of

The magnet 14 is constructed by stacking a plurality of ring-shaped split magnets 15 in the axial direction.
The split magnets 15 are, for example, neodymium-iron-
It is made of a boron-based material or a samarium-cobalt-based material, and is magnetized so that N poles and S poles are alternately arranged in the circumferential direction. Therefore, the magnet 14 is divided into a plurality of pieces in the direction intersecting the direction in which the magnetic poles are arranged, that is, in the axial direction. A relatively thin ring-shaped plate member 16 made of a magnetic material such as a silicon steel plate having a surface coated with an insulating layer 16a such as a resin layer is sandwiched between the divided magnets 15 as shown in FIG. The insulating layer 16a of the plate member 16 electrically insulates the split magnets 15 from each other.

In the above structure, the plurality of armature coils 5 are sequentially controlled to be turned on and off during operation of the motor. Since the strength of the magnetic field of the armature coil 5 changes due to the interruption of the electric current of the armature coil 5, an eddy current is generated in the magnet 14 under the influence thereof. In this case, in the conventional case where the magnet is composed of a single magnet, the eddy current flows as a passage in the entire axial direction of the magnet M as shown by an arrow A in FIG. Since the static resistance is small, the current value becomes large.

However, according to this embodiment, the magnet 14 is divided into a plurality of divided magnets 15 in the direction intersecting with the direction in which the magnetic poles are arranged, that is, in the radial gap type motor, the eddy current is divided. Flows into each of the divided magnets 15 as indicated by an arrow B in FIG. 3, so that the passage of the eddy current becomes narrow, and as a result,
Even if the split magnet 15 is made of a material having a low electric resistance such as neodymium-iron-boron type or samarium-cobalt type, the electric resistance of the eddy current passage becomes large and only a small eddy current flows. Therefore,
Eddy current loss is reduced and motor efficiency is increased.

Here, the eddy current loss We is generally We =
It is represented by σe · t ² · f ² · B ² . Σe is a constant determined by the material, t is the thickness, f is the frequency of the alternating magnetic field, and B is the maximum magnetic flux density. Therefore, the magnet 14
It is understood that the eddy current loss can be reduced by dividing the thickness into smaller thickness (axial length).

By the way, since the eddy current flows in the surface layer, it is conceivable to fit a cylindrical body made of laminated steel plates to the outer peripheral portion of the magnet in order to reduce the eddy current. Since the distance between the stator core and the magnet is increased, the effective magnetic flux density is reduced and the motor efficiency is reduced. However, in this embodiment, since the eddy current can be reduced without providing the tubular body made of laminated steel plates, the distance between the stator core 4 and the magnet 14 can be shortened and the efficiency reduction can be avoided. It is a thing.

Further, in this embodiment, the split magnet 15 is used.
Since the mutual insulation is performed by the plate member 16 made of a magnetic material coated with the insulating layer 16a, the plate member 16 is also magnetized and a force for attracting the split magnets 16 on both sides is generated. When the S and N poles are fixed to the rotor yoke 13 so that they are at the same position in the circumferential direction, the repulsive force acting between the divided magnets 15 can be reduced, and the fixing work becomes easier.

FIG. 4 shows a second embodiment of the present invention. The difference from the first embodiment is that the split magnet 15 is used.
An insulating layer 15a made of a resin layer is coated on the above, and the insulating layers 15a insulate the divided magnets 15 from each other. In such a configuration, the split magnets 15 can be stacked without a gap, so that they are magnetically equivalent to the conventional single magnet, and the motor efficiency is further improved.

FIG. 5 shows a third embodiment of the present invention. The difference from the first embodiment is that each split magnet 1
5, the split magnet 1 extends on the outer peripheral surface, which is the surface facing the armature coil 5, in the circumferential direction in which the magnetic poles are arranged.
5, a plurality of recesses, which in this embodiment are narrow grooves 17, are formed in parallel with each other in the axial direction.

In the case of such a configuration, considering that the eddy current flows in the surface layer of the split magnets 15, it is equivalent to that each split magnet 15 is further divided in the axial direction with respect to the passage of the eddy current. Therefore, the passage is further narrowed, and the eddy current can be further reduced.

FIG. 6 shows a fourth embodiment of the present invention. The difference from the first embodiment is that each split magnet 1
5, the split magnet 1 extends on the outer peripheral surface, which is the surface facing the armature coil 5, in the circumferential direction in which the magnetic poles are arranged.
5, a plurality of protrusions 18 that go around 5 are formed in parallel in the axial direction. Here, the axial width dimension of the convex portion 18 is set to be equal to the portion (the portion indicated by reference numeral 19) which becomes the concave portion by forming the projecting portion 18. Even with such a configuration, since each split magnet 15 is equivalent to the passage of the eddy current being further divided in the axial direction, the passage is further narrowed, and the eddy current can be further reduced. In addition, as the convex portion 18,
It may have a narrow lower width similar to the groove 17.

FIG. 7 shows a fifth embodiment of the present invention. The difference from the first embodiment is that the field magnet is composed of a single magnet 20 without being divided, Of the magnet 20, the armature coil 5
A narrow groove 21 as a recess that extends along the circumferential direction, which is the direction in which the magnetic poles are arranged, and goes around the magnet 20, is formed on the outer peripheral surface that is opposite to the magnetic poles in the axial direction that intersects the direction in which the magnetic poles are arranged. It is in the place where multiple pieces were formed.

In such a structure, considering that the eddy current flows in the surface layer of the magnet 20 as described above, the passage of the eddy current is the same as in the case where the magnet 20 is composed of a plurality of divided magnets. Is equivalent to the axial division, the passage is narrowed, and the eddy current can be reduced.

FIG. 8 shows a sixth embodiment of the present invention in which a field magnet is a single magnet 22.
The structure of the magnet 22 is the same as that of the fifth embodiment, but the magnet 22 extends on the outer peripheral surface of the magnet 22 facing the armature coil 5 along the circumferential direction in which the magnetic poles are arranged. A plurality of convex portions 23 that make a circle are formed in parallel with each other in the axial direction, which is the direction intersecting the direction in which the magnetic poles are arranged. Here, the vertical width of the convex portion 23 is a portion that becomes a concave portion by forming the convex portion 23 (reference numeral 2).
(Portion indicated by 4).

Even with this structure, since the eddy current flows in the surface layer of the magnet 22, it is equivalent to the magnet 22 being divided in the axial direction with respect to the passage of the eddy current, so that the passage is narrowed. Eddy current can be reduced. Further, since the magnet 22 is single and not divided, no assembly work for combining the divided magnets is required, which is advantageous in terms of cost. The convex portion 23
As the groove 21, the lower width may be the same as that of the groove 21.

FIG. 9 shows a seventh embodiment of the present invention. This embodiment is applied to an axial gap type motor in which a field magnet 25 and an armature coil (not shown) are arranged so as to face each other in the axial direction. The armature coil constitutes, for example, a stator yoke. The magnets 25 are circularly arranged on the surface of the steel plate with an insulating member interposed therebetween, and the magnets 25 are formed in a disk shape, and are attached to a disk-shaped rotor yoke so as to face the armature coil in the axial direction.

The magnet 25 is divided into a plurality of pieces in the radial direction, that is, in the direction intersecting the circumferential direction in which the N and S magnetic poles are arranged, and the divided magnets 26 are arranged concentrically. ing. Although not shown, the split magnets 26 are electrically insulated from each other by a ring-shaped steel plate coated with an insulating layer, an insulating layer coated on the split magnets 26, and the like. Even with this structure, the eddy current flows in the magnet 25 in the radial direction, but since the magnet 25 is divided into a plurality of parts in the radial direction, the passage of the eddy current is narrowed and the eddy current can be reduced.

The present invention is not limited to the embodiments described above and shown in the drawings, but the following modifications and extensions are possible. On the surface of the split magnet 26 facing the armature coil, a plurality of convex portions or concave portions extending in the circumferential direction may be formed in the radial direction, and the magnet 25 is composed of a single magnet. A plurality of convex portions or concave portions may be formed concentrically on the surface opposite to.
The electric insulation between the divided magnets 15 and 26 may be performed by a gap. The armature coil may be provided on the rotor side and the field magnet may be provided on the stator side.

[0029]

As described above, according to the present invention, the following effects can be obtained. In the motor according to claim 1, the magnet is divided into a plurality of portions in a direction intersecting the direction in which the magnetic poles are arranged, and the divided magnets are electrically insulated from each other, so that an eddy current (eddy current loss) flowing through the magnet is reduced. Can be done and efficiency is increased.

In the motor according to the second aspect, since the split magnets are electrically insulated from each other by the insulating layer coated on the split magnets, the split magnets can be coupled without a gap and can be magnetically isolated. It can be as good as one magnet.

In the motor according to the third aspect of the present invention, the divided magnets are electrically insulated from each other by a plate material made of a magnetic material coated with an insulating layer. Since the repulsive force acting on can be reduced, workability is improved.

According to another aspect of the motor of the present invention, a plurality of protrusions or recesses extending in the direction in which the magnetic poles are arranged are formed on the surface of the split magnet facing the armature coil in a direction intersecting with the direction in which the magnetic poles are arranged. As a result, the eddy current can be further reduced.

According to another aspect of the motor of the present invention, a plurality of protrusions or recesses extending along the direction of arrangement of the magnetic poles are formed on the surface of the magnet facing the armature coil in a direction intersecting the direction of arrangement of the magnetic poles. Thus, it is possible to configure the magnet with a single magnet without dividing the magnet into a plurality of parts, which is excellent in workability.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a first embodiment of the present invention.

FIG. 2 is a partial vertical sectional view of a field magnet.

FIG. 3 is a partially developed view of a field magnet.

FIG. 4 is a view corresponding to FIG. 2 showing a second embodiment of the present invention.

FIG. 5 is a diagram corresponding to FIG. 2 showing a third embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 2 showing a fourth embodiment of the present invention.

FIG. 7 is a vertical cross-sectional view of a field magnet showing a fifth embodiment of the present invention.

FIG. 8 is a vertical sectional view of a field magnet showing a sixth embodiment of the present invention.

FIG. 9 is a plan view of a field magnet showing a seventh embodiment of the present invention.

FIG. 10 is a view corresponding to FIG. 3 showing a conventional field magnet.

[Explanation of Codes] 3 is a motor case, 5 is an armature coil, 6 is a stator,
9 is a rotor, 14 is a field magnet, 15 is a split magnet, 15a is an insulating layer, 16 is a plate material, 16a is an insulating layer, 17 is a groove (recess), 18 is a convex part, 20 is a magnet, 21 is a groove (Concave part), 22 is a magnet, 23 is a convex part, 25 is a magnet, and 26 is a split magnet.

Claims (5)

[Claims] 1. A motor in which a magnet for field is provided on one of a stator and a rotor and an armature coil is provided on the other, and the magnet is divided into a plurality in a direction intersecting a direction in which magnetic poles are arranged. A motor characterized in that the split magnets are electrically insulated from each other. 2. The motor as claimed in claim 1, wherein the split magnets are electrically insulated from each other by an insulating layer coated on the split magnets. 3. The motor according to claim 1, wherein electrical insulation between the split magnets is performed by a plate made of a magnetic material coated with an insulating layer. 4. The split magnet, wherein a plurality of convex portions or concave portions extending in the direction in which the magnetic poles are arranged are formed on the surface facing the armature coil in a direction intersecting with the direction in which the magnetic poles are arranged. The motor according to any one of 1. 5. A motor having a field magnet provided on one of a stator and a rotor, and an armature coil provided on the other, in a surface of the magnet facing the armature coil, along a direction in which magnetic poles are arranged. A motor having a plurality of convex portions or concave portions extending in a direction intersecting a direction in which magnetic poles are arranged.