JP2022184651A - Method of manufacturing pm motor, and pm motor - Google Patents

Abstract

To provide a method of manufacturing a permanent magnet (PM) motor, which prevents damage to a rotor core, and the PM motor.SOLUTION: A method of manufacturing a permanent magnet (PM) motor includes: a coil arrangement step of arranging a coil 4 in a slot 32 of a stator core 3; a resin path formation step of forming resin paths 3a, 3b and 3c on an inside-diameter side surface of the stator core 3 by arranging a mold 100 in a rotor insertion part of the PM motor 1; and a mold resin layer formation step of forming a mold resin layer 5 for coating the inside-diameter side surface of the stator and the coil 4, by hardening a resin after making the resin flow between the coils 4 and through the resin paths 3a, 3b and 3c.SELECTED DRAWING: Figure 1

Description

The present invention relates to a PM (Permanent Magnet) motor manufacturing method and a PM motor.

A PM motor as shown in Patent Document 1 is used for various purposes. For example, in testing automobile parts such as engines and motors, high-speed PM motors with a peripheral speed of about 150 m/s (540 km/h) and a rotation speed of 20000 r/min are used.

JP 2019-132220 A

When using a PM motor, the rotor may be inserted into or pulled out of the stator when replacing bearings or the like. At this time, damage such as scratches may occur in the rotor core.

Bearings are attached to both sides of the PM motor, and if one bearing is removed for replacement of the bearings, the rotor comes into contact with the stator due to its own weight or the attractive force of the permanent magnet. If the lock nut is tightened in this state, the rotor will rotate, and the rotor will be dented and damaged.

A centrifugal force acts on the rotor of a PM motor during operation. Since the centrifugal force (F=mrω ² ) is proportional to the square of the number of revolutions, a higher centrifugal force is generated when the rotor rotates at high speed. Particularly in high-speed PM motors, this centrifugal force may cause cracks to grow starting from damaged portions of the rotor core, resulting in failure of the motor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a PM motor manufacturing method and a PM motor that prevent damage to the rotor core.

A PM motor manufacturing method as a first aspect of the present invention includes a coil placement step of placing a coil in a slot of a stator core, and a mold die placed in a rotor insertion portion of the PM motor to form a mold on the inner diameter side surface of the stator core. a resin path forming step of forming a resin path; and after flowing resin between the coils and in the resin path, curing the resin to form a mold resin layer covering the inner diameter side surface of the stator core and the coil. , and a molding resin layer forming step.

According to one embodiment of the present invention, there is provided a method for manufacturing a PM motor, in which, in the resin path forming step, a resin path is also formed on the outer diameter side surface of the stator core, and the resin path on the outer diameter side surface is formed on the stator core. Preferably, the skew extends helically on the outer diameter side of the .

In the PM motor manufacturing method as one embodiment of the present invention, it is preferable that the resin path is a skew extending spirally on the inner diameter side surface of the stator core.

In the PM motor manufacturing method as one embodiment of the present invention, the PM motor is preferably a high-speed PM motor.

In the PM motor manufacturing method as one embodiment of the present invention, the mold resin layer forming step is preferably performed under low vacuum or normal pressure.

A PM motor as a second aspect of the present invention includes: a stator core having a resin path on an inner diameter side surface; coils arranged in slots of the stator core; and a molded resin layer covering the side surface and the coil.

According to the present invention, it is possible to provide a PM motor manufacturing method and a PM motor that prevent damage to the rotor core.

FIG. 4 is a cross-sectional view taken along a plane passing through the center of the mold when injecting mold resin from the connection side coil end in manufacturing the PM motor; It is a figure which shows the outer diameter side surface of a stator core. 4 is a flow chart showing a method of manufacturing a PM motor according to one embodiment of the present invention; Regarding the finished product of the PM motor according to one embodiment of the present invention, the part above the center axis of the rotor shows a cross section cut along a plane passing through the center axis, and the part below the center axis of the rotor shows the outer shape of the PM motor. FIG. 4 is a diagram showing (frame). FIG. 2 is an enlarged cross-sectional view showing the vicinity of the stator core in a cross section taken along line VV in FIG. 1;

A PM motor according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view taken along a plane passing through the center of the mold when injecting mold resin from the connection side coil end in manufacturing the PM motor. The PM motor 1 includes a stator core 3 , a coil 4 including a connection-side coil end 4 a and an anti-connection-side coil end 4 b , a mold resin layer 5 , a connection portion 6 , and an outer frame 10 . The PM motor 1 is engaged with the mold 100 when the molding resin is injected.

The mold 100 has a columnar shape with a flange. The mold 100 is arranged in the rotor inserting portion into which the rotor 2 (see FIG. 4) is inserted, so that the flange portion is present on the side opposite to the connection side coil end 4b in this embodiment. The injected molding resin flows outside the mold 100 .

The stator core 3 has a cylindrical shape and is arranged to surround the mold 100 . In addition, as shown in FIG. 5, the stator core 3 has a plurality of teeth 31 protruding radially inward and arranged at equal intervals in the circumferential direction on its inner diameter side surface.

A resin path 3a is formed on the inner diameter side surface of the stator core 3 (the gap between the stator core 3 and the mold 100). Further, in this embodiment, a resin path 3c is also formed on the outer diameter side surface of the stator core 3. As shown in FIG. FIG. 2 is a diagram showing the outer diameter side surface of the stator core 3. As shown in FIG. A resin passage 3 c is formed on the outer side surface of the stator core 3 and spirally extends on the outer diameter side surface of the stator core 3 around the rotation axis of the stator core 3 . The resin path 3c is skewed to reduce torque ripple. As will be described later, the resin path 3c is a welding groove that is welded to form the stator core 3 by laminating and integrating the thin plates.

The slots 32 are skewed to reduce torque ripple. That is, the slots 32 extend spirally around the rotation axis of the stator core 3 . As shown in FIG. 5 , the slots 32 are provided with coils 4 that are wound around the stator core 3 . Current flows from a terminal box 14 (FIG. 4), which will be described later, to the connection portion 6 to energize the coil 4, thereby rotating the rotor around its central axis.

As shown in FIG. 5 , resin paths 3 b are formed between the strands of the coil 4 in the slots 32 of the stator core 3 . Resin paths 3 b are formed between coils 4 wound around stator core 3 .

The connection-side coil end 4 a and the opposite connection-side coil end 4 b come out from one of the slots 32 of the stator core 3 and are connected to the coil of the next slot 32 .

As shown in FIG. 1, the mold resin layer 5 is formed on the inner diameter side surface and the welding groove 3c of the outer diameter side surface of the stator core 3 to cover and seal the inner diameter side surface and the outer diameter side surface of the stator core 3 . In this embodiment, as shown in FIG. 5 , the mold resin layer 5 is formed between the strands of the coil 4 inside the teeth 31 of the stator core 3 and completely covers the coil 4 . The mold resin layer 5 is formed by flowing resin between the coils 4 and along the resin paths 3a, 3b, and 3c, as will be described later. In this embodiment, the mold resin layer 5 has insulating properties.

Referring to FIG. 5, air layer 7 exists between rotor 2 and mold resin layer 5 on the inner diameter side surface of stator core 3 . By making the outer diameter of the mold 100 (FIG. 1) larger than the outer diameter of the rotor 2 (FIG. 4), a mold resin layer 5 and an air layer 7 are formed between the stator core 3 and the rotor 2 as shown in FIG. are formed when the motor is completed.

The outer frame 10 is a frame forming the surface of the PM motor 1 .

The effects of the PM motor 1 of this embodiment will be described below with reference to FIG.

The presence of the mold resin layer 5 between the rotor 2 and the stator core 3 prevents direct contact between the rotor 2 and the stator core 3, thereby preventing damage to the rotor core 2c. In addition, when the PM motor 1 operates, the coil 4 reaches a high temperature of about 200° C. However, by covering the coil 4 with the mold resin layer 5, the lubricating oil of the bearing 13 is prevented from being ignited by the high temperature coil 4. be able to. In addition, by covering the coil 4 with the mold resin layer 5 , it is possible to prevent sparks from occurring in the coil 4 . From these points of view, it is preferable that the mold resin layer 5 completely covers the coil 4 inside the tooth portion 31 of the stator core 3 .

The presence of air pockets in the mold resin layer 5 causes heat spots. However, since the mold resin layer 5 of this embodiment is formed by flowing resin through the resin paths 3a, 3b, and 3c, it is difficult for air to accumulate as described later.

A method of manufacturing a PM motor according to one embodiment of the present invention will be described below with reference to the drawings.

First, in the resin path forming step, the mold 100 is arranged at the rotor insertion portion of the stator core 3 so that the resin path 3a is formed on the inner diameter side of the stator core 3 . Moreover, in this embodiment, the stator core 3 is formed by laminating and welding a plurality of plates such that the resin paths 3c are formed. A laser, for example, can be used for welding.

Next, a method for manufacturing the PM motor 1 will be described with reference to FIG. In step S<b>101 , the coil 4 is arranged in the slot 32 of the stator core 3 by winding the coil 4 around the stator core 3 in the slot 32 between the teeth 31 on the inner diameter side of the stator core 3 . In this embodiment, the coil 4 is distributed over a plurality of slots 32 and wound, and the method of winding the coil 4 in this embodiment is called distributed winding. A resin path 3 b is now formed between the coils 4 .

After that, in step S102, as shown in FIG. 1, resin is poured from the mold inlet 8 above the connection side coil end 4a.

As shown in FIG. 1, consider a case where resin flows only through resin paths 3b formed between coils 4 wound around a stator core 3. FIG. In this case, since the coil 4 is arranged, the resin is less likely to flow to the coil end 4b on the opposite side of the mold inlet 8 in the longitudinal direction. In contrast, in this embodiment, the resin path 3a is formed on the inner diameter side surface of the stator core 3, and the welding groove 3c is formed on the outer diameter side surface of the stator core 3. It becomes easy to flow to the anti-connection side coil end 4b on the opposite side in the longitudinal direction. In addition, by pouring the resin from the mold injection port 8, the coil ends 4a and 4b of the enameled wire are entirely filled with the resin, and the bearing lubricating oil does not adhere.

Thus, in this embodiment, in addition to the resin path 3b, the resin path 3a and the welding groove 3c on the outer diameter side surface of the stator core 3 are provided, so that the resin can easily flow from the mold inlet 8 to the coil end 4b on the opposite side. This makes it easier to remove air pockets.

In this embodiment, the resin flows over the resin path 3b and the welding groove 3c on the outer diameter side surface of the stator core 3, thereby generating a swirling flow at the exit of the stator core 3 surrounded by the dotted line in FIG. Thereby, the fluidity of the resin can be enhanced. From the viewpoint of further enhancing the fluidity, it is preferable that the resin path 3b and the welding groove 3c are skewed so as to spirally extend around the rotation axis of the stator core 3 as in this embodiment.

Although the resin is injected from the connection side coil end 4a in this embodiment, the same effect can be obtained by injecting the resin from the opposite connection side coil end 4b.

After the resin flows on the inner diameter side surface of the stator core 3, on the welding grooves 3c on the outer diameter side surface, and around the coil 4, in step S103, the resin is cured by heating or the like, and the inner diameter side surface and the outer diameter side surface of the stator core 3 are hardened. A mold resin layer 5 covering the welding groove 3c and the coil 4 is formed. In the conventional technique, air pockets tend to occur especially when the coil is distributed winding, but in this embodiment, step S102 can be performed under low vacuum or normal pressure. This eliminates the need for large-scale equipment and processes for creating a high-vacuum environment, making it possible to reduce the manufacturing cost of the PM motor 1 . The required vacuum environment is considered to change depending on the viscosity of the mold resin used.

FIG. 4 is a cross-sectional view of the finished PM motor 1 according to one embodiment of the present invention, taken along a plane passing through the central axis of the rotor 2. As shown in FIG. The PM motor 1 includes a rotor 2 including a rotor core 2c and magnets 2m, a stator core 3, a coil 4 including a connection side coil end 4a and an anti-connection side coil end 4b, a mold resin layer 5, a connection portion 6, an outer A frame 10, a shaft 11, a lock nut 12, a bearing 13 and a terminal box 14 are provided. Descriptions of the constituent elements described above with reference to FIG. 1 will be omitted below.

The rotor 2 has a cylindrical shape. The rotor 2 is fixed to the shaft 11 and rotates together with the shaft 11 . As shown in FIG. 5 , permanent magnets 2 m are provided radially outward of the rotor 2 along the circumferential direction of the rotor 2 .

The lock nut 12 tightens the bearing 13 supporting the rotor 2 and the shaft 11 from the outside while the rotor 2 is inserted inside the stator core 3 .

The terminal box 14 is provided with a connecting portion to the motor cable and the power cable routed from the connecting portion 6 . The connection is covered with an insulator. A voltage is applied to the connection portion 6 via the terminal box 14 to cause a current to flow through the connection portion 6 .

1 PM motor 2 rotor 2c rotor core 2m magnet 3 stator core 31 stator core tooth 32 stator core slot 3a stator core resin path 3b stator core resin path 3c stator core resin path (welding groove)
4 coil 5 mold resin layer 6 connection part 7 air layer 8 mold inlet 10 outer frame 11 shaft 12 lock nut 13 bearing 14 terminal box 100 mold

Claims (5)

A method for manufacturing a PM motor,
a coil placement step of placing the coils in the slots of the stator core;
a resin path forming step of placing a mold in the rotor insertion portion of the PM motor to form a resin path on the inner diameter side surface of the stator core;
a mold resin layer forming step of forming a mold resin layer covering the inner diameter side surface of the stator core and the coil by flowing the resin between the coils and the resin path, and then curing the resin;
A method of manufacturing a PM motor, comprising: 3. The resin path forming step also forms a resin path on the outer diameter side surface of the stator core, and the resin path on the outer diameter side surface is a skew extending spirally on the outer diameter side surface of the stator core. 2. A method for manufacturing a PM motor according to 1. 2. The method of manufacturing a PM motor according to claim 1, wherein said PM motor is a high speed PM motor. 2. The method of manufacturing a PM motor according to claim 1, wherein said mold resin layer forming step is performed under low vacuum or normal pressure. a stator core having a resin path on the inner diameter side surface;
coils disposed in slots of the stator core;
a mold resin layer provided between the coils and on the resin path and covering the inner diameter side surface of the stator core and the coil;
PM motor.

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