WO2023233538A1

WO2023233538A1 - Core of electric motor

Info

Publication number: WO2023233538A1
Application number: PCT/JP2022/022184
Authority: WO
Inventors: 大暉梶田
Original assignee: ファナック株式会社
Priority date: 2022-05-31
Filing date: 2022-05-31
Publication date: 2023-12-07

Abstract

A plurality of pin holes (12) are formed in an end surface of a core (10) of this electric motor. The core includes a plurality of pins (20) inserted into the respective plurality of pin holes. At least one of the pins includes a curved portion (21) at least partly curved relative to an axial direction of the pin. The pin hole into which said at least one pin is inserted is formed in such a manner as to conform to the curved portion.

Description

electric motor core

Embodiments of the present invention relate to a core of an electric motor.

A core of an electric motor includes a stator and a rotor that rotates with respect to the stator (for example, Japanese Patent Application Publication No. 2010-259256). The core of such a motor may be a laminate formed by laminating a plurality of magnetic plates, such as iron plates, carbon steel plates, and electromagnetic steel plates, in the axial direction of the core.

Japanese Patent Application Publication No. 2010-259256

A plurality of through holes are formed in each of the plurality of magnetic plates. In the core as a laminate, a plurality of through holes in adjacent magnetic plates are aligned with each other to form a plurality of pin holes. Therefore, inside the core, a plurality of pin holes extend in the stacking direction of the core (in the axial direction of the core). Then, a plurality of pins are press-fitted into the plurality of pin holes from the end face of the core, thereby bonding the plurality of magnetic plates to each other and forming a strong core.

A relatively large force is required to insert the pin into the pin hole. For this reason, there is a need for an electric motor core in which a pin can be easily press-fitted into a pin hole and a plurality of magnetic plates can be firmly connected.

According to a first aspect of the present disclosure, in the core of an electric motor, a plurality of pin holes are formed in an end surface of the core, and further includes a plurality of pins inserted into each of the plurality of pin holes. At least one of the plurality of pins includes a curved portion that is at least partially curved with respect to the axial direction of the at least one pin, and the at least one pin is inserted into the plurality of pins. A core is provided, wherein at least one of the pin holes is configured to fit the curved portion of the at least one pin.

The objects, features, and advantages of the present invention will become more apparent from the following description of the embodiments in conjunction with the accompanying drawings.

FIG. 1 is a sectional view of an electric motor according to a first embodiment of the present invention. 2 is a radial cross-sectional view of the rotor shown in FIG. 1; FIG. FIG. 2B is a partial axial cross-sectional view of the rotor taken along line A-A' in FIG. 2A; It is a figure which shows the first modification of a pin hole. It is a figure which shows the second modification of a pin hole. It is a figure which shows the third modification of a pin hole. It is a figure which shows the fourth modification of a pin hole. FIG. 3 is a perspective view of a pin having a C-shaped cross section and a pin having an annular cross section. FIG. 3 is a partial radial cross-sectional view of a rotor according to a second embodiment of the invention. FIG. 7 is a partial radial cross-sectional view of a rotor according to a third embodiment of the invention. FIG. 7 is a partial radial cross-sectional view of a rotor according to a fourth embodiment of the present invention. FIG. 7 is a partial radial cross-sectional view of a rotor based on another modification of the fourth embodiment. FIG. 7 is a partial radial cross-sectional view of a rotor based on yet another modification of the fourth embodiment. FIG. 7 is a partial radial cross-sectional view of a rotor according to a fifth embodiment of the invention. FIG. 7 is another partial radial cross-sectional view of a rotor according to a fifth embodiment of the invention; FIG. 7 is a partial axial cross-sectional view of a rotor according to a fifth embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings. Corresponding components are given common reference numerals throughout the drawings.
FIG. 1 is a sectional view of an electric motor according to a first embodiment of the present invention. As shown in FIG. 1, the electric motor 1 includes a stator 9 and a rotor 10 rotatably supported by the stator 9. A first bearing 7 and a second bearing 8 are arranged on the inner peripheral surface of the stator 9. A shaft portion 5 passing through the rotor 9 is rotatably supported by the stator 9 by a first bearing 7 and a second bearing 8. Note that a detector 6 is attached to one end of the stator 9 to detect the rotational speed of the shaft portion 5 and the like.

The rotor 10 of the electric motor 1 will be used as the "core of the electric motor" in this specification. However, it should be noted that the "core of the motor" includes the stator 9 of the motor 1 and that the following description also applies to the core as stator 9.

2A is a radial cross-sectional view of the rotor shown in FIG. 1, and FIG. 2B is a partial axial cross-sectional view of the rotor taken along line A-A' in FIG. 2A. As can be seen from FIG. 2A, the rotor 10 is annular and has a hole formed in its center into which the shaft 5 (not shown in FIG. 2A) is inserted. Further, as can be seen from FIG. 2B, the rotor 10 is formed by laminating a plurality of magnetic plates (core plates) 11 having the same shape, such as iron plates, carbon steel plates, and electromagnetic steel plates in the axial direction of the rotor 10.

In addition, in the first embodiment and some embodiments to be described later, the rotor 10 and the stator 9 do not need to be formed from a plurality of magnetic plates 11, and the rotor 10 and the stator 9 may be made of a ferrite core, a powdered iron core, or the like. It may be an integral member made from a magnetic material.

Referring to FIG. 2A, a plurality of pin holes 12 are formed in the rotor 10 at equal intervals in the circumferential direction. As can be seen with reference to FIG. 2B, each of the plurality of magnetic plates 11 is formed with (a plurality of) through holes. When a plurality of magnetic plates 11 are stacked, the through holes are aligned with each other to form the pin holes 12 described above.

A pin 20 is inserted into each of the plurality of pin holes 12 in the axial direction of the rotor 10. Strictly speaking, the pins 20 are press-fitted into corresponding pin holes 12 for the purpose of fastening adjacent magnetic plates 11 to each other.

As can be seen from FIG. 2B, the pin 20 may have a curved portion 21 that is at least partially curved in its axial direction. Such a curved portion 21 contacts the inner wall of the pin hole 12, and as a result, frictional resistance increases and it may be difficult to press fit the pin 20 into the pin hole 12.

Therefore, in the first embodiment, at least one pin hole 12 among the plurality of pin holes 12 is formed to fit the curved portion 21 of the pin 20. In other words, the pin hole 12 is formed to accommodate the curved portion 21 of the pin 20. For example, such a pin hole 12 has an elliptical cross section in the radial direction of the rotor 10. As can be seen from FIG. 2B, in such a configuration, the contact area between the pin 20 and the rotor 10 is reduced, and the frictional resistance when the pin 20 is press-fitted into the pin hole 12 is reduced. Therefore, the pin 20 can be easily press-fitted into the pin hole 12, and the plurality of magnetic plates 11 can be firmly connected. As a result, the production efficiency of the rotor 10 can be improved.

By the way, FIG. 4 is a perspective view of a pin with a C-shaped cross section and a pin with an annular cross section. A pin 20 with a C-shaped cross section is shown on the left side of FIG. 4, and a pin 20' with an annular cross section is shown on the right side of FIG. In the past, C-shaped pins 20 were often used in order to easily press-fit the pins 20 into the pin holes 12, but the C-shaped pins 20 had the disadvantage of being relatively expensive.

As described above, in the first embodiment, the pin hole 12 is formed to fit the curved portion 21 of the pin 20, so the pin 20 can be press-fitted relatively easily. Therefore, in the first embodiment, it is not necessary to use the relatively expensive C-shaped pin 20, and it is possible to use the relatively inexpensive annular pin 20'. As can be seen, the manufacturing cost of the rotor 10 can therefore be reduced. Note that, as a matter of course, the C-shaped pin 20 may also be used in the first embodiment.

FIGS. 3A to 3D are diagrams showing modified examples of pin holes. FIG. 3A shows a pin hole 12a having an oval cross section, similar to FIG. 2A and the like. In FIG. 3A, regarding the cross section of the pin hole 12a, the longest line segment R1a that connects the center of the cross section and the edge of the cross section with the longest distance, and the shortest line segment that connects the center of the cross section and the edge of the cross section with the shortest distance. R2a can be defined. In FIG. 3A, the longest line segment R1a and the shortest line segment R2a correspond to the long axis and short axis of the ellipse, respectively.

FIG. 3B shows a pin hole 12b with a rectangular cross section. Similarly, regarding the cross section of the pin hole 12b, the longest line segment R1b that connects the center of the cross section and the edge of the cross section with the longest distance, and the shortest line segment R2b that connects the center of the cross section and the edge of the cross section with the shortest distance. can be defined.

Further, FIG. 3C shows a pin hole 12c with an oval cross section, and FIG. 3D shows a pin hole 12d with an elongated hexagonal cross section. Similarly, regarding the cross section of the pin hole 12c, the longest line segment R1c that connects the center of the cross section and the edge of the cross section with the longest distance, and the shortest line segment R2c that connects the center of the cross section and the edge of the cross section with the shortest distance. can be defined. Furthermore, regarding the cross section of the pin hole 12d, the longest line segment R1d that connects the center of the cross section and the edge of the cross section with the longest distance, and the shortest line segment R2d that connects the center of the cross section and the edge of the cross section with the shortest distance. Can be defined.

By the way, a figure that has the property of completely overlapping the original figure when it is rotated by 360/n degrees around a single point (n is an integer of 2 or more) has "n-fold symmetry". It is generally said to have.

As can be seen from FIGS. 3A to 3D, the pin holes 12a to 12d overlap the original pin holes 12a to 12d when rotated by 180 degrees around the center of each cross section. Therefore, the pin holes 12a to 12d have "two-fold symmetry."

The diameter of the pin 20 is approximately equal to the shortest line segment R2a to R2d of the pin holes 12a to 12d. Therefore, the pin 20 is arranged so that the curved portion 21 of the pin 20 is directed toward the side edge of the longest line segment R1a to R1d of the pin holes 12a to 12d, or so that the curved portion 21 is located on the longest line segment R1a to R1d. is preferably positioned relative to the pin hole 12. After or while positioning, the pins 20 are press-fitted into the pin holes 12a to 12d.

In this case, the curved portion 21 of the pin 20 does not or hardly contacts the side edges of the longest line segments R1a to R1d. Therefore, the frictional resistance when press-fitting the pin 20 into the pin hole 12 is reduced, and the pin 20 can be press-fitted easily. Therefore, effects similar to those described above can be obtained. Note that the cross section of the pin hole 12 may have another shape having two-fold symmetry, such as an elongated polygon. In such a case, it will be understood that the manufacturing cost of the rotor 10 can be reduced.

FIGS. 5A and 5B are partial radial cross-sectional views of rotors according to the second and third embodiments of the present invention. In FIGS. 5A and 5B, only a portion of the rotor 10 is shown when the electric motor 1 incorporating the rotor 10 is being driven. In these drawings, centrifugal force FC due to rotation of rotor 10 acts in the radial direction of rotor 10, and force FR due to torque reaction acts in the circumferential direction of rotor 10. A plurality of pin holes 12 having an oval cross section are formed in the rotor 10.

In the second embodiment shown in FIG. 5A, it is assumed that the centrifugal force FC is smaller than the reaction force FR. That is, the electric motor 1 in the second embodiment is, for example, a large torque motor. In such an electric motor 1, as shown in FIG. 5A, it is preferable to form the pin hole 12 so that the longest line segment R1a (see FIG. 3A, etc.) of the pin hole 12 extends in the radial direction of the rotor 10. preferable.

If the centrifugal force FC is smaller than the reaction force FR, the pin 20 may move in the circumferential direction of the rotor 10 when the electric motor 1 is driven, and the coupling between the plurality of magnetic plates 11 may become insufficient. be. However, in the second embodiment, the pin 20 comes into contact with the pin hole 12 without any gap in the circumferential direction of the rotor 10. Therefore, in the second embodiment, the pin 20 does not move in the circumferential direction even when the electric motor 1 is driven, and as a result, the electric motor 1 can be driven stably.

In the third embodiment shown in FIG. 5B, the centrifugal force FC is greater than the reaction force FR. That is, the electric motor 1 in the third embodiment is, for example, a high-speed rotation type motor. In such an electric motor 1, as shown in FIG. 5B, it is preferable to form the pin hole 12 so that the longest line segment R1a (see FIG. 3A, etc.) of the pin hole 12 extends in the circumferential direction of the rotor 10. preferable.

If the centrifugal force FC is larger than the reaction force FR, there is a possibility that the pin 20 will move in the radial direction of the rotor 10 when the electric motor 1 is driven, resulting in insufficient coupling between the plurality of magnetic plates 11. be. However, in the third embodiment, the pin 20 contacts the pin hole 12 without any gap in the radial direction of the rotor 10. Therefore, in the third embodiment, the pin 20 does not move in the radial direction even when the electric motor 1 is driven, and as a result, the electric motor 1 can be driven stably.

FIG. 6 is a partial radial cross-sectional view of a rotor according to a fourth embodiment of the present invention, and is a view similar to FIGS. 5A and 5B. In the fourth embodiment, it is assumed that the centrifugal force FC and the reaction force FR are approximately equal to each other. In FIG. 6, a plurality of

pin holes

12e, 12f, 12g, 12h, and 12i are formed at equal intervals in the circumferential direction of the rotor 10. In FIG. 6, the

pin holes

12e, 12g, 12i are inclined clockwise with respect to the radial direction of the rotor 10, and the

pin holes

12f, 12h are inclined counterclockwise with respect to the radial direction of the rotor 10. ing. In other words, in FIG. 6, clockwise

inclined pin holes

12e, 12g, 12i and counterclockwise

inclined pin holes

12f, 12h are arranged alternately.

It will be seen that in such a configuration, when the electric motor 1 is driven, the pin 20 does not move in either the radial direction or the circumferential direction of the rotor 10, and as a result, the electric motor 1 can be driven stably. .

Further, in FIG. 6, the angle A1 at which the pin hole 12h is inclined counterclockwise with respect to the radial direction of the rotor 10 is approximately equal to the angle A2 at which the pin hole 12i is inclined clockwise with respect to the radial direction of the rotor 10. preferable. The same applies to the counterclockwise or clockwise inclined angles of other pin holes. In this case, the electric motor 1 can be driven more stably.

Furthermore, FIG. 7A is a partial radial sectional view of a rotor based on another modification of the fourth embodiment, and FIG. 7B is a partial radial sectional view of a rotor based on still another modification of the fourth embodiment. It is. 7A and 7B are similar to FIGS. 5A and 5B, and in these drawings as well, it is assumed that the centrifugal force FC and the reaction force FR are approximately equal to each other.

In FIG. 7A, a plurality of

pin holes

12j, 12k, 12l, 12m, 12n, 12o, and 12p are formed at equal intervals in the circumferential direction of the rotor 10. As illustrated, the

pin holes

12j, 12m, and 12n are inclined clockwise with respect to the radial direction of the rotor 10. Furthermore, the pin holes 12k, 12l, 12o, and 12p are inclined counterclockwise with respect to the radial direction of the rotor 10. Therefore, every

second pin hole

12k, 12l, 12o, 12p tilted counterclockwise and

pin hole

12j, 12m, 12n tilted clockwise are arranged. It is clear that even in such a case, the same effects as described above can be obtained. Further, a counterclockwise inclined pin hole and a clockwise inclined pin hole may be arranged every plurality (three or more).

In FIG. 7B, a plurality of

pin holes

12q, 12r, 12s, 12t, 12u, 12v, and 12w are formed at equal intervals in the circumferential direction of the rotor 10. As illustrated, the pin holes 12s and 12w are inclined clockwise with respect to the radial direction of the rotor 10. Furthermore, the pin holes 12q, 12r, 12t, 12u, and 12v are inclined counterclockwise with respect to the radial direction of the rotor 10. Therefore, the counterclockwise

inclined pin holes

12q, 12r, 12t, 12u, and 12v and the clockwise inclined pin holes 12s and 12w are randomly arranged. In other words, some of the pin holes are tilted counterclockwise, and the remaining pin holes are tilted clockwise. Preferably, the number of pin holes tilted counterclockwise and the number of pin holes tilted clockwise are approximately equal to each other. It is obvious that the same effects as described above can be obtained with such a configuration as well.

8A is a partial radial cross-sectional view of a rotor according to a fifth embodiment of the present invention, FIG. 8B is another partial radial cross-sectional view of a rotor according to a fifth embodiment of the present invention, and FIG. 8C is a partial radial cross-sectional view of a rotor according to a fifth embodiment of the present invention. FIG. 3 is a partial axial sectional view of a rotor according to a fifth embodiment of the present invention.

In FIG. 8A, a plurality of pin holes 12 are formed at equal intervals in the circumferential direction of the magnetic plate 11A. Also in FIG. 8B, a plurality of pin holes 12' are formed at equal intervals in the circumferential direction of the magnetic plate 11B. However, the plurality of pin holes 12' in FIG. 8B are arranged radially outward than the plurality of pin holes 12 shown in FIG. 8A. Note that the cross section of the pin hole 12 in the fifth embodiment does not need to have two-fold symmetry, and the cross section of the pin hole 12 in the fifth embodiment may be circular.

As shown in FIG. 8C, a plurality of magnetic plates 11B are arranged above and below the rotor 10. The plurality of magnetic plates 11A are arranged between the plurality of upper magnetic plates 11B and the plurality of lower magnetic plates 11B. As a result, a pin hole 12x having a stepped inner surface is formed.

If the pin 20 is curved in a substantially C-shape as shown in FIG. 8C, the curved portion 21 of the pin 20 will fit along the stepped portion of the pin hole 12x. That is, in the fifth embodiment, the positions of the plurality of through holes in each of the

magnetic plates

11A and 11B are made different from each other depending on the curved portion 21 of the pin 20. With such a configuration, the frictional resistance when press-fitting the pin 20 into the pin hole 12x is reduced, and the pin 20 can be press-fitted easily. Therefore, effects similar to those described above can be obtained.

Note that the number of magnetic plates 11B on the upper and lower sides of the rotor 10 and the number of the plurality of magnetic plates 11A are changed as appropriate depending on the shape of the curved portion 21 of the pin 20. Further, the number of magnetic plates 11B above or below the rotor 10 may be zero. Furthermore, it is within the scope of the fifth embodiment to use three or more types of magnetic plates with different positions of through holes so that a plurality of steps are formed.

Thus, in all embodiments of the invention, the pin hole 12 has a shape that matches/accommodates the curved portion 21 of the pin 20. Therefore, since the pin hole 12 has such a shape, when the pin 20 is press-fitted into the pin hole 12, the contact area between the pin 20 and the rotor 10 can be reduced, and the frictional resistance can be reduced. Therefore, the pin 20 can be easily press-fitted into the pin hole 12, and the plurality of magnetic plates 11 can be firmly connected. As a result, the production efficiency of the rotor 10 can be improved.

Furthermore, the core in the embodiment described above may be applied to an electromagnetic device other than an electric motor, such as a core of a reactor or a transformer, and even such a case is within the scope of the present invention.

Although the embodiments of the present disclosure have been described in detail, the present disclosure is not limited to the individual embodiments described above. These embodiments are subject to various additions, substitutions, and changes without departing from the gist of the invention or the spirit and spirit of the present invention derived from the contents described in the claims and equivalents thereof. , partial deletion, etc. are possible. For example, in the embodiments described above, the order of each operation and the order of each process are shown as examples, and are not limited to these.

1 Electric motor 5 Shaft part 7, 8 Bearing 9 Stator (core)
10 Rotor (core)
11, 11A, 11B Magnetic plate (core plate)
12, 12a to 12x Pin hole 20, 20' Pin 21 Curved portion R1a to R1d Longest line segment R2a to R2d Shortest line segment

Claims

In the core of the electric motor,
A plurality of pin holes are formed in the end surface of the core,
further comprising a plurality of pins inserted into each of the plurality of pin holes,
At least one of the plurality of pins includes a curved portion that is at least partially curved with respect to the axial direction of the at least one pin,
At least one pin hole of the plurality of pin holes into which the at least one pin is inserted is formed to fit the curved portion of the at least one pin.
The core according to claim 1, wherein a cross section of the at least one pin hole in the radial direction of the core has two-fold symmetry.
3. The core of claim 2, wherein the cross section is selected from an ellipse, an oval, a rectangle, or an elongated hexagon.
The core according to claim 1, wherein each of the plurality of pins has an annular cross section.
When the centrifugal force that should act on the core is smaller than the reaction of the torque that should act on the core, the longest line segment connecting the center of the cross section of the at least one pin hole and the edge of the cross section by the longest distance is 3. The core of claim 2, wherein the core is arranged in a radial direction of the core.
When the centrifugal force that should act on the core is larger than the reaction of the torque that should act on the core, the longest line segment connecting the center of the cross section of the at least one pin hole and the edge of the cross section by the longest distance is The core according to claim 2, wherein the core is arranged in a circumferential direction of the core.
When the centrifugal force that should act on the core is equal to the reaction of the torque that should act on the core, the center of the cross section of some of the at least one pin hole and the edge of the cross section. The longest line segment connecting the longest distance is arranged so as to be inclined clockwise in the core with respect to the radial direction of the core, and the longest portion of the remaining pin hole among the at least one pin hole The core according to claim 2, wherein the core is arranged to be inclined counterclockwise with respect to a radial direction of the core.
The inclination angle at which the longest line segment of the cross section of some of the pin holes is inclined in the clockwise direction of the core with respect to the radial direction of the core is such that the longest line segment of the remaining pin holes is inclined in the radial direction of the core. 8. The core of claim 7, wherein the inclination angle of the core is equal to the counterclockwise inclination angle of the core.
The core according to claim 7 or 8, wherein the part of the pin holes and the remaining pin holes are arranged every other pin hole or every other pin hole.
The core is formed by laminating a plurality of core plates,
A plurality of through holes corresponding to the plurality of pin holes are formed in each of the plurality of core plates,
The plurality of through holes of the plurality of core plates are aligned with each other to form the plurality of pin holes,
The core according to claim 1 or 2, wherein the positions of the plurality of through holes in each of the plurality of core plates are different from each other depending on the curved portion of the at least one pin.