JPH09322450A - Rotor for electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor which can strengthen the fixing of a magnet by using conductive fiber with the generation of heat caused by an eddy current being prevented and can improve the performance and rotation of an electric motor. SOLUTION: A magnet 14 is bonded around a rotor core 11 which is constituted by laminating a hollow disc 24, a filament winding layer 16 is formed on the external circumferential surface of the magnet 14, and the magnet 14 is fixed. The filament winding layer 16 is constituted by winding glass fiber bundles 20 and carbon fiber bundles 22 alternately. Therefore, carbon fiber bundles 22 which include conductivity are insulated to each other by the glass fiber bundles 20, and an eddy current can be prevented from flowing through the filament winding layer 16 in its axial direction during rotation of a rotor 10. It is thus possible to suppress heat generation caused by the eddy current during rotation of the rotor 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor rotor, and more particularly to an electric motor rotor used at high speed.

[0002]

2. Description of the Related Art In an electric motor, in order to minimize the distance between a magnet on the rotor side and a stator arranged around the rotor, the magnet is fixed on the surface of the rotor. In this case, as a method of fixing the magnet to the rotor surface, a method of adhering the magnet to the rotor surface with an adhesive is generally used in a small motor having a low rotation speed. Also, in a motor with a high rotation speed, if the magnet is only fixed to the rotor surface with an adhesive, the magnet may peel off during rotation. The method of fixing to the rotor surface is adopted. Japanese Patent Application Laid-Open No. 61-1246 discloses a technique for fixing a magnet on the surface of a rotor with a fiber for fixing the magnet.

FIG. 6 shows a magnet fixing method disclosed in the above-mentioned conventional example. In FIG. 6, a plurality of permanent magnets 103 are arranged on the outer periphery of the cylindrical rotor core 102 fixed to the shaft 100. This permanent magnet 103
The adhesive 104 bonds the permanent magnet 103 and the cylindrical rotor core 102 and the permanent magnets 103 to each other. Glass fibers 105 impregnated with a thermosetting resin are wound around the outer peripheral surface of the permanent magnet 103, and the permanent magnet 103 is heated and hardened so that the permanent magnet 103 is fixed to the rotor core 102.
It is fixed on the outer circumference of. In this conventional example, the glass fiber 105 is wound in two layers.

In the above-mentioned conventional example, glass fiber is used as a material for the fiber wound around the outer circumference of the permanent magnet 103 in order to prevent generation of eddy current. When the permanent magnet 103 is wound with a conductive fiber, an eddy current is generated in the fiber layer, and the heat generated from the permanent magnet demagnetizes the permanent magnet, or an adhesive or a thermosetting resin impregnated in the fiber. Cause heat deterioration. Therefore, the permanent magnet 1
It was necessary to use non-conductive glass fiber as the material of the fiber wound around the outer periphery of 03.

[0005]

However, the electric motor,
Especially for electric motors used in electric vehicles,
High rotation speed exceeding 10,000 rpm is required. Therefore, as a fiber used to wind and fix the outer periphery of the permanent magnet 103, the glass fiber 105 has a problem of insufficient strength.

Therefore, in order to cope with the high rotation of the electric motor, it is necessary to use a fiber having a higher strength and a higher elasticity than the glass fiber, but generally, a fiber material satisfying such a condition is not electrically conductive. Have For example, carbon fiber is a material having very high strength and elastic modulus as compared with glass fiber, but very good conductivity.

Conventionally, such a highly conductive fiber material cannot be used for fixing the permanent magnet 103 because eddy current is generated.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to prevent the heat generation due to an eddy current and to firmly fix a magnet by using a conductive fiber, thereby improving the performance of an electric motor. It is to provide a rotor of an electric motor that enables higher speed and higher rotation speed.

[0009]

In order to achieve the above object, the present invention is an electric motor in which a magnet is arranged on the outer circumference of a rotor core, and a fiber for fixing the magnet is wound around the outer peripheral surface of the magnet to fix the magnet. A motor rotor, characterized in that glass fibers and conductive fibers having higher strength and elasticity than glass fibers are used as fibers for fixing a magnet, and these fibers are alternately wound.

In the rotor of the electric motor,
Carbon fibers are preferably used as the conductive fibers.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a front view and a side view of a rotor of an electric motor according to the present invention. In FIG. 1A, salient poles 12 are formed on the rotor core 11, and a region on the outer circumference of the rotor core 11 sandwiched by the salient poles 12 is
The magnet 14 is arranged and bonded by an adhesive. In this example, four salient poles 12 and four magnets 14 are arranged. A filament winding layer 16 is formed on the outer peripheral surface of the magnet 14 and the outer peripheral surface of the salient pole 12 by winding the fiber for fixing the magnet according to the present invention. The rotor 10 of the present embodiment is formed by the above configuration.

As shown in FIG. 1 (b), the rotor core 11 is fixed to a shaft 18 and is rotated by this. The width L of the rotor core 11 is appropriately selected according to the application. Further, it is preferable that the thickness t of the filament winding layer 16 wound around the outer peripheral surface of the magnet 14 is as small as possible because the distance between the magnet 14 and a stator (not shown) arranged on the outer periphery of the rotor 10 can be reduced. However, it is preferable to set it to 1 mm or less.

FIG. 2 shows how the filament winding layer 16 is formed by winding fibers around the outer peripheral surface of the magnet 14. In FIG. 2, the filament winding layer 16 formed on the outer peripheral surface of the magnet 14 is composed of a fiber bundle made of two different materials. One is a glass fiber bundle 20 and the other is a carbon fiber bundle 22, which are impregnated with epoxy resin which is a thermosetting resin. Each fiber bundle 20, 22
Are bundled with a predetermined number of primary fibers and have approximately the same thickness.

As shown in FIG. 2, the glass fiber bundle 20
The carbon fiber bundles 22 and the carbon fiber bundles 22 are wound so as to be alternately arranged on the outer peripheral surface of the magnet 14. In this case, FIG.
As shown in, the set of the glass fiber bundle 20 and the carbon fiber bundle 22 is wound at the winding pitch p. In addition,
This winding pitch p is appropriately adjusted by the diameter of the glass fiber bundle 20 and the carbon fiber bundle 22 used and the tension applied to both fiber bundles 20, 22.

FIG. 3 shows a partial sectional view of the III-III section of FIG. 1 (a). In FIG. 3, the rotor core 11 is arranged around the shaft 18, the magnet 14 is arranged on the outer periphery of the rotor core 11, and the filament winding layer 16 is formed on the outer peripheral surface of the magnet 14. As described above, the filament winding layer 16 is formed by winding the glass fiber bundles 20 and the carbon fiber bundles 22 alternately. In the example shown in FIG. 3, the glass fiber bundle 20 and the carbon fiber bundle 22 are
It is shown that and are wound three times back and forth.

A feature of the present invention is that the glass fiber bundles 20 and the carbon fiber bundles 22 are alternately arranged. That is, in the rotor 10 shown in FIG. 3, an eddy current is generated in the axial plane by the magnetic field generated by the magnet 14 and the stator (not shown). But,
The carbon fiber bundles 22 having high conductivity are partitioned by the glass fiber bundles 20 having high electric resistance, and eddy currents generated in the axial plane are blocked by the glass fiber bundles 20, so that the generation of eddy currents is suppressed. be able to.

Also in the rotor core 11, the shaft 18
In the structure, a large number of hollow discs 24 having holes are laminated in a portion corresponding to the above. The hollow discs 24 are insulated from each other by forming an insulating coating. Therefore, also in the rotor core 11, the eddy current generated in the axial plane is suppressed.

With the above configuration, even if the rotor 10 rotates during driving of the electric motor, it is possible to suppress the generation of an eddy current in the rotor 10, and the magnet 14 is demagnetized due to the heat generated by the eddy current. It is possible to prevent the thermosetting resin impregnated in both fiber bundles 20 and 22 or the adhesive or the like for bonding the magnet 14 to the rotor 10 from being thermally deteriorated.

Further, in this embodiment, the magnet 14
Since the carbon fiber bundle 22 having high strength and elasticity is used in addition to the glass fiber bundle 20 to fix the
The magnet 14 is more firmly fixed, the strength of the rotor 10 can be increased, and the rotation speed of the rotor 10 can be increased.

Next, a method of manufacturing the rotor 10 according to this embodiment will be described. FIG. 4 shows a manufacturing process of the rotor 10 of the electric motor according to the present embodiment. In FIG. 4, the glass fiber bobbin 2 around which the glass fiber bundle 20 is wound
6 and the carbon fiber bobbin 28 around which the carbon fiber bundle 22 is wound, both fiber bundles 20 and 22 are drawn out and passed through a resin impregnation bath 30 filled with epoxy resin to impregnate the epoxy resin. The fiber bundles 20 and 22 impregnated with the epoxy resin are arranged side by side via a guide roller 32 and wound around the outer peripheral surface of the magnet 14 adhered to the outer periphery of the rotor core 11 of the rotor 10 with an adhesive. At this time, the glass fiber bundles 20 and the carbon fiber bundles 22 are alternately wound in parallel as described above, and thus are formed on the outer peripheral surface of the magnet 14 as shown in FIGS. 2 and 3. The filament winding layers 16 are alternately arranged.

The rotor 10 in which the glass fiber bundle 20 and the carbon fiber bundle 22 are wound is heat-treated to form the fiber bundle 2
The epoxy resin in 0 and 22 is hardened and the magnet 14 is fixed to the outer periphery of the rotor core 11.

Through the above steps, the magnet 14 is fixed to the rotor core 11 and the rotor 10 is formed.

As the glass fiber bundle 20 and the carbon fiber bundle 22 used in the above steps, for example, those shown in Table 1 can be used.

[0025]

[Table 1] The glass fiber bundle 20 and the carbon fiber bundle 22 used in this embodiment are bundles of a predetermined number of the glass fibers and the carbon fibers shown in Table 1 above.

Although carbon fibers are used as the conductive fibers in the above-mentioned embodiments, the carbon fibers are not particularly limited as long as they have higher strength and higher elasticity than glass fibers. Although an epoxy resin is used as the thermosetting resin, the thermosetting resin is not limited to the epoxy resin.

Next, an example of the rotor of the electric motor according to this embodiment manufactured as described above will be shown together with a comparative example.

Embodiment. The magnet 14 was arranged on the rotor core 11 having a width L = 50 mm shown in FIG. 1, and the fiber bundles 20 and 22 were alternately arranged and wound three times back and forth over the entire width by the process shown in FIG. The rotor 10 thus configured was heated to 150 ° C. and held for 2 hours to cure the epoxy resin. Tension was applied to each fiber bundle so that the winding pitch p at this time was 5 mm for each set of the glass fiber bundle 20 and the carbon fiber bundle 22. As a result of three reciprocal windings, the thickness t of the filament winding layer 16 was 0.85 mm.

At this time, the total content of glass fiber and carbon fiber in the filament winding layer 16 shown in FIG. 3 was 67% by volume, and the remaining 33% by volume was the epoxy resin. The volume ratio of carbon fiber to glass fiber in the filament winding layer 16 was 55:45.

The magnet 14 was adhered to the outer peripheral surface of the rotor core 11 with an epoxy adhesive before forming the filament winding layer 16 on the outer periphery thereof.

Comparative Example 1 The filament winding layer 16 was formed on the outer peripheral surface of the magnet 14 in the same manner as in the example by using only glass fibers without using carbon fibers. On this occasion,
The winding pitch p was 2.24 mm, and three reciprocating windings were performed. The content of glass fibers in the filament winding layer 16 was 67% by volume, and the remaining 33% by volume was the epoxy resin.

Thereafter, similarly to the embodiment, the rotor 1 was heated to 150 ° C. and held for 2 hours to cure the epoxy resin.
Formed 0.

Comparative Example 2 The filament winding layer 16 was formed on the outer periphery of the magnet 14 using only carbon fibers without using glass fibers. The winding pitch p at this time was 2.79 mm, and three reciprocating windings were performed. After that, 150 ° C
The temperature was raised to and held for 2 hours to form the rotor 10. Also in this comparative example, the carbon fiber content in the filament winding layer 16 was 67% by volume.

Comparative Example 3. The filament winding layer 16 was not formed on the outer peripheral surface of the magnet 14, and the magnet 14 was bonded to the rotor core 11 only by the adhesive.

Each of the rotors 10 constructed as in the above Examples and Comparative Examples 1, 2 and 3 was assembled into a motor and the rotational speed was gradually increased. The rotation speed of the motor when it was destroyed was measured. The surface temperature of the magnet 14 at that time was also measured. These results are shown in FIG.

In FIG. 5, the vertical axis shows the rotation speed of the motor when the magnet 14 is peeled off as the limit rotation speed (rpm). In addition, Examples and Comparative Examples 1, 2, and 3 are shown side by side.

The glass fiber used has a resistivity of 10 ¹⁵ Ωc.
m, and the resistivity of the carbon fiber is 2 × 10 ⁻³ Ωcm. Therefore, in the case of Comparative Example 1 in which the filament winding layer 16 was formed of only glass fibers, the resistivity of the filament winding layer 16 in the width direction of the rotor 10 exceeded 10 ¹⁵ Ωcm. Further, in the case of the example, glass fibers and carbon fibers were alternately arranged, and the resistivity thereof was 10 ¹³ Ωcm. Therefore,
It is considered that the generation of the eddy current is greatly suppressed in both the examples and the comparative example 1, and the heat generation due to the eddy current is suppressed to be small. In Comparative Example 1, the surface temperature of the magnet 14 increased to 88 ° C. as a result of the heat generated by the stator coil being transferred to the magnet 14.

As shown in FIG. 5, in Comparative Example 1, the magnet 14 peels off at about 10,000 rpm. On the other hand, in the example, the limit rotational speed could be increased to about 13000 rpm. This is considered to be a result of the fact that the strength of the filament winding layer 16 was significantly improved by using the carbon fiber having a higher strength than that of Comparative Example 1 together with the glass fiber. In addition, in the example, the surface temperature of the magnet 14 is 103 ° C. at 13000 rpm.
The surface temperature of the magnet 14 was 92 ° C. at 000 rpm. As described above, considering the heat transfer from the coils of the stator, it is considered that the heat generation amounts of the example and the comparative example 1 are almost the same.

From the above, in the case of this example, as compared with the comparative example 1, it was possible to improve the strength of the rotor 10 in comparison with the glass fiber alone while suppressing the heat generation due to the eddy current.

Further, in Comparative Example 2, the filament winding layer 16 was formed only of carbon fibers, but in this case, the resistivity of the rotor 10 in the width direction was 10 ^-1 Ωcm. Therefore, an eddy current is generated in the filament winding layer 16 to generate heat, and the epoxy resin of the thermosetting resin is thermally deteriorated, and the magnet 14 is peeled off at about 9000 rpm. At this time, the surface temperature of the magnet was 280 ° C.

From the evaluation results of this comparative example, it was found that even if the carbon fiber having high strength is used, the strength of the rotor 10 becomes lower than the case where the glass fiber is used due to the heat generation by the eddy current.

In Comparative Example 3, the magnet 14 was adhered and fixed to the rotor core 11 only with the adhesive, but the strength was extremely insufficient and the magnet 14 peeled off at 4000 rpm.

From the above evaluation results, it was found that the rotor of the electric motor according to this embodiment has higher strength than conventional rotors.

[0044]

As described above, according to the present invention,
The conductive fiber with high strength and elastic modulus is used to firmly fix the magnet, and both sides of this conductive fiber are insulated by the non-conductive fiber to suppress the generation of eddy current and generate heat. Can be suppressed.

Therefore, since fibers having high strength and high elastic modulus can be used while preventing the generation of eddy currents, a rotor having a firmly fixed magnet can be obtained, and the electric motor has high performance and high rotation. It is possible to deal with

[Brief description of drawings]

FIG. 1 is a front view and a side view of a rotor of an electric motor according to the present invention.

FIG. 2 is an explanatory diagram showing how a filament winding layer is formed on the outer peripheral surface of a magnet.

FIG. 3 is a partial cross-sectional view taken along the line III-III in FIG.

FIG. 4 is an explanatory diagram of a manufacturing process of the rotor of the electric motor according to the present invention.

FIG. 5 is a graph showing performance evaluation results of a rotor of an electric motor according to the present invention and a comparative example.

FIG. 6 is a sectional view of a rotor of a conventional electric motor.

[Explanation of symbols]

10 rotor, 11 rotor core, 12 salient pole, 14
Magnet, 16 filament winding layer, 18
Shaft, 20 glass fiber bundle, 22 carbon fiber bundle, 24
Hollow disk, 26 glass fiber bobbin, 28 carbon fiber bobbin, 30 resin impregnation bath, 32 guide roller.

Claims (2)

[Claims] 1. A rotor for an electric motor in which a magnet is arranged on the outer periphery of a rotor core, and a fiber for fixing the magnet is wound around the outer peripheral surface of the magnet to fix the magnet, wherein the fiber for fixing the magnet is used. A rotor for an electric motor, characterized in that glass fibers and conductive fibers having higher strength and elasticity than glass fibers are used and these fibers are alternately wound. 2. The rotor for an electric motor according to claim 1, wherein carbon fibers are used as the conductive fibers.