CN216774412U

CN216774412U - Rotor for motor

Info

Publication number: CN216774412U
Application number: CN202220275253.XU
Authority: CN
Inventors: 那须野喜史
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2022-02-10
Filing date: 2022-02-10
Publication date: 2022-06-17
Anticipated expiration: 2032-02-10

Abstract

The utility model provides a rotor for a motor. The rotor for the motor comprises a rotor core formed by laminating a plurality of steel plates with punched holes, and a shaft fixed in a shaft hole formed by the punched holes on the plurality of steel plates through burning and embedding, wherein the plurality of steel plates forming the rotor core are divided into a first group and a second group by taking the middle position of the rotor core as a boundary in the laminating direction of the steel plates, and each steel plate belonging to the first group is configured in such a way that burrs generated on the periphery of the punched holes are positioned on one side far away from the middle position; each of the steel plates belonging to the second group is configured such that a burr generated on a periphery of the punched hole thereof is located on a side away from the intermediate position. With the above structure, the reduction of the fastening force can be avoided, and the rotor core and the shaft can be firmly combined.

Description

Rotor for motor

Technical Field

The present invention relates to a rotor for a motor.

Background

Conventionally, a rotor for a motor has been widely used in which a shaft is inserted and fixed into a shaft hole of a rotor core by shrink fitting. Fig. 11 is a sectional view showing such a motor rotor.

As shown in fig. 11, the rotor core 52 is formed by laminating a plurality of steel plates 54 each having a punched hole formed by press working, and the shaft hole of the rotor core 52 is formed by the punched hole of each steel plate 54. The punched hole in each steel plate 54 is formed by punching the steel plate 54 from the top down. When the upstream side in the press direction of the punched portion of the steel plate 54 is sheared, the portion is cut from the middle to the lower end. Therefore, the upper portion of the periphery of the punched hole in the steel plate 54 is sheared to generate the sagging 56, and the lower portion of the periphery of the punched hole in the steel plate 54 is cut to generate the burr 57.

In general, the plurality of steel plates 54 constituting the rotor core 52 are divided into an upper group 60 and a lower group 70 with the intermediate position of the rotor core 52 as a boundary in the stacking direction of the steel plates 54. Each steel plate 54 belonging to the upper group 60 is arranged such that a burr 57 generated at the periphery of the punched hole is located on the lower side; each steel plate 54 belonging to the lower group 70 is arranged such that a burr 57 generated on the periphery of the punched hole thereof is located on the upper side.

In such a configuration, as shown in fig. 12, after the shaft 53 is inserted into the shaft hole of the rotor core 52 by shrink fitting, the rotor core 52 applies a fastening force F to the shaft 53. At this time, an elastic deformation force Z1 acting downward is generated on the outer diameter side of each steel plate 54 belonging to the upper group 60, and an elastic deformation force Z2 acting upward is generated on the outer diameter side of each steel plate 54 belonging to the lower group 70. Therefore, the plurality of steel plates 54 belonging to the upper group 60 and the plurality of steel plates 54 belonging to the lower group 70 are inclined away from each other on the inner diameter side. As a result, the fastening force F may be reduced, and the coupling force between the rotor core 52 and the shaft 53 may be weakened.

SUMMERY OF THE UTILITY MODEL

In view of the above circumstances, an object of the present invention is to provide a motor rotor in which a core and a shaft can be firmly coupled.

In order to solve the above-described problems, the present invention provides a rotor for a motor including a rotor core formed by stacking a plurality of steel plates on which punched holes are formed, and a shaft fixed by shrink-fitting into a shaft hole formed by the punched holes of the plurality of steel plates, the rotor comprising: the plurality of steel plates constituting the rotor core are divided into a first group and a second group in a stacking direction of the steel plates, with a middle position of the rotor core as a boundary, and the steel plates belonging to the first group are arranged such that burrs generated at a periphery of the punched holes are located on a side away from the middle position; each of the steel plates belonging to the second group is configured such that a burr generated on a peripheral edge of the punched hole thereof is located on a side away from the intermediate position.

In the rotor for a motor according to the present invention, the fastening force of the steel plates acting on the shaft due to the shrink fit causes the shaft to shrink in the shaft hole, and at this time, the elastic deformation force generated in the outermost steel plate and the elastic deformation force generated in the remaining steel plates in the first group are opposite in direction and cancel each other out; in the second group, the elastic deformation force generated in the outermost steel plate and the elastic deformation force generated in the remaining steel plates are opposite in direction and cancel each other out. As a result, the fastening force can be prevented from being reduced, and the rotor core and the shaft can be firmly coupled to each other.

In the motor rotor according to the present invention, it is preferable that the first group and the second group are further divided into two sub groups in a stacking direction of the steel plates.

Drawings

Fig. 1 is a sectional view showing a motor rotor according to an embodiment of the present invention.

Fig. 2 is a diagram for explaining the directions of the forces and elastic deformations acting on the respective portions in fig. 1.

Fig. 3 is an enlarged view of the region indicated by (3) in fig. 2.

Fig. 4 is an enlarged view of the region indicated by (4) in fig. 2.

Fig. 5 is an enlarged view of the region indicated by (5) in fig. 2.

Fig. 6 is an enlarged view of the region indicated by (6) in fig. 2.

Fig. 7 is a perspective view showing a part of the rotor being cut out.

Fig. 8 is a cross-sectional view showing a motor rotor according to a modification (a) of the present invention.

Fig. 9 is a sectional view showing a rotor for a motor according to a modification (two) of the present invention.

Fig. 10 is a cross-sectional view showing a motor rotor according to a modification (iii) of the present invention.

Fig. 11 is a sectional view showing a rotor for a motor according to the related art.

Fig. 12 is a diagram for explaining a problem in the rotor in fig. 11.

Detailed Description

Hereinafter, a rotor for a motor according to an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 is a sectional view showing a motor rotor according to the present embodiment. As shown in fig. 1, a motor rotor (hereinafter referred to simply as a rotor) 1 includes a rotor core 2 and a shaft 3.

The rotor core 2 is formed by press-working (punching) a steel plate 4 having a predetermined thickness into a predetermined shape having a punched hole, and then laminating a plurality of the steel plates 4 subjected to the press-working. Therefore, the rotor core 2 has a shaft hole 21 (see fig. 7) formed by punching holes in the plurality of steel plates 4 at a central portion thereof. The shaft 3 is inserted and fixed into the shaft hole 21 of the rotor core 2 by shrink fitting.

The punched hole in each steel plate 4 is formed by press working from the top to the bottom, and the portion to be pressed in the steel plate 4 is cut at the upstream side in the press direction, and then the portion is cut from the middle to the lower end. Here, a surface cut by the press working is referred to as a cut surface 41, and a surface cut by the press working is referred to as a cut surface 42.

Due to the shearing, sagging 43 is generated at the upper portion of the periphery of the punched hole in the steel plate 4; due to the above-described breakage, a burr 44 is generated at the lower portion of the peripheral edge of the punched hole in the steel plate 4.

In the present embodiment, as shown in fig. 1, the plurality of steel plates 4 constituting the rotor core 2 are divided into an upper group (first group) 10 and a lower group (second group) 20 with a middle position of the rotor core 2 as a boundary in the stacking direction of the steel plates 4 (here, the stacking direction is defined as the vertical direction), the upper group 10 is located above the middle position, and the lower group 20 is located below the middle position. Each steel plate 4 belonging to the upper group 10 is arranged such that a burr 44 generated at the periphery of the punched hole is located on the upper side (the side away from the intermediate position); each steel plate 4 belonging to the lower group 20 is arranged such that a burr 44 generated at the periphery of the punched hole is positioned on the lower side (the side away from the intermediate position).

Next, a process of coupling the rotor core 2 and the shaft 3 will be described.

First, a plurality of steel plates 4 are laminated. At this time, each steel plate 4 belonging to the upper group 10 is arranged such that its sheared surface 41 is located on the lower side and its fractured surface 42 is located on the upper side; each steel plate 4 belonging to the lower group 20 is arranged such that its sheared surface 41 is located on the upper side and its broken surface 42 is located on the lower side.

Next, the shaft 3 is subjected to shrink fitting. Specifically, the shaft hole 21 of the laminated rotor core 2 is heated to be expanded in diameter, and then the shaft 3 is fitted into the shaft hole 21. Thus, when the temperature of the rotor core 2 is lowered, the rotor core 2 is fixedly coupled to the shaft 3. In this state, the end ring 5 is mounted as shown in fig. 7.

Next, the operation and effect of the rotor 1 having the above-described configuration will be described.

As shown in fig. 2, since the shaft 3 is coupled to the rotor core 2 by shrink fitting, the steel plates 4 apply a fastening force F to the shaft 3, and the portion of the shaft 3 in the shaft hole 21 is reduced in diameter. Thus, in the shaft hole 21, the outer peripheral surfaces of the upper end portion and the lower end portion of the shaft 3 are respectively bent toward the center direction of the shaft hole 21, and the outer peripheral surfaces of the remaining portions of the shaft 3 linearly extend in the longitudinal direction thereof.

In the present embodiment, the plurality of steel plates 4 constituting the rotor core 2 are divided into the upper group 10 and the lower group 20 at the intermediate position in the stacking direction as a boundary, and the burr 44 generated at the periphery of the punched hole in each steel plate 4 belonging to the upper group 10 is located on the upper side, and the burr 44 generated at the periphery of the punched hole in each steel plate 4 belonging to the lower group 20 is located on the lower side. Therefore, after the shaft 3 is partially reduced in diameter in the shaft hole 21, the uppermost steel plate 4 in the upper group 10 generates an elastic deformation force X1 (see fig. 2) acting downward when receiving a rotational force R1, because the upper end of the punched periphery of the steel plate is close to the shaft 3 and the lower end is far from the shaft 3, as shown in fig. 3; on the contrary, in the steel plates 4 other than the uppermost steel plate 4 in the upper group 10, as shown in fig. 4, the upper end of the punched hole periphery is far from the shaft 3 and the lower end is close to the shaft 3, so that an elastic deformation force X2 (see fig. 2) acting upward is generated when receiving a rotating force R2; further, as shown in fig. 5, the lowermost steel plate 4 in the lower group 20 has a punched hole whose upper end is distant from the shaft 3 and whose lower end is close to the shaft 3, and thus receives a rotational force R3 to generate an elastic deformation force Y1 (see fig. 2) acting upward; in contrast, as shown in fig. 6, the steel plates 4 in the lower group 20 except the steel plate 4 at the lowermost layer have punched holes whose upper ends are close to the shaft 3 and lower ends are distant from the shaft 3, and thus a downward elastic deformation force Y2 (see fig. 2) is generated when receiving a rotational force R4.

Thereby, in the upper group 10, the elastic deformation force X1 and the elastic deformation force X2 cancel each other; in the lower group 20, the elastic deformation force Y1 and the elastic deformation force Y2 cancel each other out. Therefore, the plurality of steel plates 4 of the upper group 10 and the plurality of steel plates 4 of the lower group 20 are not inclined apart from each other. As a result, the fastening force F can be prevented from decreasing, and the rotor core 2 and the shaft 3 can be firmly coupled to each other.

Therefore, when the motor (not shown) is manufactured by combining the rotor 1 having the above-described structure with the stator (not shown), the assembly accuracy between the rotor 1 and the stator can be improved.

The present invention is not limited to the description of the above embodiments, and various applications and modifications can be made without departing from the spirit thereof.

For example, fig. 8 shows a modification (one) of the present invention. This modification (a) is different from the above-described embodiment in that the upper group 10 and the lower group 20 of the rotor core 2 are further divided into two sub groups in the respective lamination directions.

Specifically, the upper half of the upper group 10 is the 1 st subgroup 10A, and the lower half of the upper group 10 is the 2 nd subgroup 10B; the upper half of the lower group 20 is the 1 st subgroup 20A and the lower half of the lower group 20 is the 2 nd subgroup 20B.

The other structure of the modification (a) is the same as that of the above embodiment, and therefore, the description thereof is omitted. The same operation and effect as those of the above embodiment can be obtained by the present modification (one).

Fig. 9 shows a modification (two) of the present invention. This modification (two) is different from the modification (one) shown in fig. 8 in that the number of steel plates 4 in the 1 st group 10A of the upper group 10 is greater than the number of steel plates 4 in the 2 nd group 10B, and the number of steel plates 4 in the 1 st group 20A of the lower group 20 is less than the number of steel plates 4 in the 2 nd group 20B.

The other structure of this modification (ii) is the same as that of the above embodiment, and therefore, the description thereof is omitted. The same operation and effect as those of the above embodiment can be obtained also by the present modification (ii).

Fig. 10 shows a modification (iii) of the present invention. This modification (three) is different from the modification (one) shown in fig. 8 in that the number of steel plates 4 in the 1 st group 10A of the upper group 10 is larger than the number of steel plates 4 in the 2 nd group 10B, and the number of steel plates 4 in the 1 st group 20A of the lower group 20 is larger than the number of steel plates 4 in the 2 nd group 20B.

The other configurations of this modification (iii) are the same as those of the above embodiment, and therefore, the description thereof is omitted. The same operation and effect as those of the above embodiment can be obtained also by the present modification (iii).

Claims

1. A rotor for a motor, comprising a rotor core formed by laminating a plurality of steel plates on which punched holes are formed, and a shaft fixed by shrink-fitting into a shaft hole formed by the punched holes in the plurality of steel plates, wherein:

the plurality of steel plates constituting the rotor core are divided into a first group and a second group with a middle position of the rotor core as a boundary in a stacking direction of the steel plates,

each of the steel plates belonging to the first group is configured such that a burr generated on a peripheral edge of the punched hole thereof is located on a side away from the intermediate position; each of the steel plates belonging to the second group is configured such that a burr generated on a peripheral edge of the punched hole thereof is located on a side away from the intermediate position.

2. A rotor for a motor according to claim 1, wherein:

the first group and the second group are further divided into two subgroups in the stacking direction of the steel sheets, respectively.