Electric motor core
By designing pin holes in the electric motor core to fit the shape of the pins, the challenge of high insertion force is overcome, resulting in cost-effective and efficient assembly of magnetic plates for stable motor operation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- FANUC LTD
- Filing Date
- 2022-05-31
- Publication Date
- 2026-05-11
AI Technical Summary
Existing electric motor cores require a large force to press-fit pins into pin holes, making the coupling of magnetic plates difficult and inefficient.
The pin holes in the electric motor core are designed with a curved portion that fits the shape of the pins, reducing frictional resistance and allowing easy press-fitting of pins, thereby facilitating firm coupling of magnetic plates.
This design reduces manufacturing costs and improves production efficiency by enabling easy and secure bonding of magnetic plates, ensuring stable motor operation.
Smart Images
Figure 0007856761000001 
Figure 0007856761000002 
Figure 0007856761000003
Abstract
Description
Technical Field
[0001] Embodiments of the present invention relate to a core of an electric motor.
Background Art
[0002] A core of an electric motor as an electric motor includes a stator and a rotor that rotates with respect to the stator (for example, Japanese Patent Application Laid-Open No. 2010-259256). Such a core of an electric motor may be a laminate formed by laminating a plurality of magnetic plates, for example, an iron plate, a carbon steel plate, and an electromagnetic steel plate in the axial direction of the core.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] A plurality of through holes are formed in each of the plurality of magnetic plates. In the core as a laminate, the plurality of through holes in adjacent magnetic plates are aligned with each other to form a plurality of pin holes. Therefore, inside the core, the plurality of pin holes extend in the stacking direction (axial direction of the core) 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 coupling the plurality of magnetic plates to each other to form a rigid core.
[0005] A relatively large force is required to insert the pin into the pin hole. For this reason, there is a demand for a core of an electric motor that can easily press-fit the pin into the pin hole and firmly couple a plurality of magnetic plates.
Means for Solving the Problems
[0006] According to a first aspect of the present disclosure, in a core of an electric motor, a plurality of pin holes are formed on the end face of the core, and further comprising a plurality of pins into which each of the plurality of pin holes is inserted, wherein 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 at least one of the plurality of pin holes into which the at least one pin is inserted is the curved portion of the at least one pin absorb A core is provided that is formed in such a way.
[0007] The object, features, and advantages of the present invention will become even clearer from the following description of embodiments related to the accompanying drawings. [Brief explanation of the drawing]
[0008] [Figure 1] This is a cross-sectional view of an electric motor according to the first embodiment of the present invention. [Figure 2A] Figure 1 is a radial cross-sectional view of the rotor. [Figure 2B] This is a partial cross-sectional view of the rotor in the axial direction along the line A-A' in Figure 2A. [Figure 3A] This figure shows the first modified example of a pinhole. [Figure 3B] This figure shows a second modified example of a pinhole. [Figure 3C] This figure shows a third modified example of a pinhole. [Figure 3D] This is a diagram showing the fourth type of pinhole torture. [Figure 4] This is a perspective view of a pin with a C-shaped cross-section and a pin with an annular cross-section. [Figure 5A] This is a radial partial cross-sectional view of a rotor according to a second embodiment of the present invention. [Figure 5B] This is a radial partial cross-sectional view of a rotor according to a third embodiment of the present invention. [Figure 6] This is a radial partial cross-sectional view of a rotor according to a fourth embodiment of the present invention. [Figure 7A]This is a radial partial cross-sectional view of the rotor based on another modification in the fourth embodiment. [Figure 7B] This is a radial partial cross-sectional view of a rotor based on yet another modification in the fourth embodiment. [Figure 8A] This is a radial partial cross-sectional view of a rotor according to the fifth embodiment of the present invention. [Figure 8B] This is another radial partial cross-sectional view of a rotor according to the fifth embodiment of the present invention. [Figure 8C] This is a partial axial cross-sectional view of a rotor according to the fifth embodiment of the present invention. [Modes for carrying out the invention]
[0009] Embodiments of the present invention will be described below with reference to the attached drawings. Throughout all drawings, corresponding components are denoted by the same reference numerals. Figure 1 is a cross-sectional view of an electric motor according to a first embodiment of the present invention. As shown in Figure 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 circumferential surface of the stator 9. A shaft portion 5 that passes through the rotor 9 is rotatably supported by the stator 9 by the first bearing 7 and the second bearing 8. A detector 6 for detecting the rotational speed of the shaft portion 5 is attached to one end of the stator 9.
[0010] In this specification, the "core of the motor" will be explained using the rotor 10 of the motor 1. However, please note that the "core of the motor" also includes the stator 9 of the motor 1, and the following explanation can also be applied to the core as the stator 9.
[0011] FIG. 2A is a radial cross-sectional view of the rotor shown in FIG. 1, and FIG. 2B is an axial partial cross-sectional view of the rotor taken along line A-A' of FIG. 2A. As can be seen from FIG. 2A, the rotor 10 is annular, and a hole into which a shaft portion 5 (not shown in FIG. 2A) should be inserted is formed at its center. Also, as can be seen from FIG. 2B, the rotor 10 is formed by laminating a plurality of magnetic plates (core plates) 11 of the same shape, for example, iron plates, carbon steel plates, electromagnetic steel plates, in the axial direction of the rotor 10.
[0012] Note that in the first embodiment and some of the embodiments described later, the rotor 10 and the stator 9 do not have to be formed from a plurality of magnetic plates 11, and the rotor 10 and the stator � may be an integral member made of a magnetic material such as ferrite or a compacted iron core.
[0013] 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 by referring to FIG. 2B, (a plurality of) through holes are formed in each of the plurality of magnetic plates 11. When the plurality of magnetic plates 11 are laminated, the through holes are aligned with each other to form the above-described pin holes 12.
[0014] A pin 20 is inserted into each of the plurality of pin holes 12 in the axial direction of the rotor10. Strictly speaking, for the purpose of fastening adjacent magnetic plates 11 to each other, the pin 20 is press-fitted into the corresponding pin hole 12.
[0015] 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, the frictional resistance increases and it may be difficult to press-fit the pin 20 into the pin hole 12.
[0016] Therefore, in the first embodiment, at least one of the multiple 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 absorb the curved portion 21 of the pin 20. Such a pin hole 12 has, for example, an elliptical cross-section in the radial direction of the rotor 10. As can be seen from Figure 2B, in this configuration, the contact area between the pin 20 and the rotor 10 is reduced, and the frictional resistance when pressing the pin 20 into the pin hole 12 is reduced. Therefore, the pin 20 can be easily pressed into the pin hole 12, and the multiple magnetic plates 11 can be firmly bonded together. As a result, the production efficiency of the rotor 10 can be improved.
[0017] By the way, Figure 4 is a perspective view of a pin with a C-shaped cross-section and a pin with an annular cross-section. On the left side of Figure 4, a pin 20 with a C-shaped cross-section is shown, and on the right side of Figure 4, a pin 20' with an annular cross-section is shown. Previously, a C-shaped pin 20 was often used to easily press-fit the pin into the pin hole 12, but a disadvantage of the C-shaped pin 20 is that it is relatively expensive.
[0018] As mentioned 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 pressed in relatively easily. For this reason, in the first embodiment, it is not necessary to use the relatively expensive C-shaped pin 20, and it is possible to use a relatively inexpensive annular pin 20'. As a result, it can be seen that the manufacturing cost of the rotor 10 can be reduced. Of course, the C-shaped pin 20 may also be used in the first embodiment.
[0019] Figures 3A to 3D show modified examples of a pinhole. Figure 3A shows a pinhole 12a with an elliptical cross-section, similar to Figure 2A. In Figure 3A, the longest line segment R1a connects the center of the cross-section to the edge of the cross-section over the longest distance, and the shortest line segment R2a connects the center of the cross-section to the edge of the cross-section over the shortest distance. In Figure 3A, the longest line segment R1a and the shortest line segment R2a correspond to the major axis and minor axis of the ellipse, respectively.
[0020] Figure 3B shows a pinhole 12b with a rectangular cross-section. Similarly, for the cross-section of the pinhole 12b, the longest line segment R1b, which connects the center of the cross-section to the edge of the cross-section by the longest distance, and the shortest line segment R2b, which connects the center of the cross-section to the edge of the cross-section by the shortest distance, can be defined.
[0021] Furthermore, Figure 3C shows a pinhole 12c with an oval cross-section, and Figure 3D shows a pinhole 12d with an elongated hexagonal cross-section. Similarly, for the cross-section of pinhole 12c, the longest line segment R1c connecting the center of the cross-section and the edge of the cross-section by the longest distance, and the shortest line segment R2c connecting the center of the cross-section and the edge of the cross-section by the shortest distance, can be defined. Furthermore, for the cross-section of pinhole 12d, the longest line segment R1d connecting the center of the cross-section and the edge of the cross-section by the longest distance, and the shortest line segment R2d connecting the center of the cross-section and the edge of the cross-section by the shortest distance, can be defined.
[0022] Incidentally, a figure that, when rotated 360 / n degrees around a single point (where n is an integer greater than or equal to 2), completely overlaps the original figure is generally said to possess "n-th symmetry."
[0023] As can be seen from Figures 3A to 3D, when the pin holes 12a to 12d are rotated 180° around the center of each cross-section, they overlap with the original pin holes 12a to 12d. Therefore, the pin holes 12a to 12d have "two-fold symmetry".
[0024] 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, it is preferable to position the pin 20 relative to the pin hole 12 such 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. Then, after or while positioning the pin 20, it is press-fitted into the pin holes 12a to 12d.
[0025] In this case, the curved portion 21 of the pin 20 does not come into contact with the longest line segment R1a to R1d side edge, or hardly comes into contact with it. Therefore, the frictional resistance when pressing the pin 20 into the pin hole 12 is reduced, and the pin 20 can be easily pressed in. For this reason, the same effect as described above can be obtained. Note that the cross-section of the pin hole 12 may also be a shape with twofold symmetry, such as an elongated polygon. In such a case, it can be seen that the manufacturing cost of the rotor 10 can be reduced.
[0026] Figures 5A and 5B are partial radial cross-sectional views of a rotor according to the second and third embodiments of the present invention. In Figures 5A and 5B, only a portion of the rotor 10 is shown when the electric motor 1 into which the rotor 10 is incorporated is being driven. In these drawings, the centrifugal force FC due to the rotation of the rotor 10 acts radially on the rotor 10, and the force FR due to the reaction of the torque acts circumferentially on the rotor 10. A plurality of pin holes 12 having an elliptical cross-section are formed in the rotor 10.
[0027] In the second embodiment shown in Figure 5A, the centrifugal force FC is assumed to be smaller than the reaction force FR. In other words, the electric motor 1 in the second embodiment is, for example, a high-torque motor. In such an electric motor 1, it is preferable to form the pin hole 12 such that the longest line segment R1a of the pin hole 12 (see Figure 3A, etc.) extends in the radial direction of the rotor 10, as shown in Figure 5A.
[0028] 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, potentially resulting in insufficient coupling between the multiple magnetic plates 11. However, in the second embodiment, the pin 20 contacts 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.
[0029] In the third embodiment shown in Figure 5B, the centrifugal force FC is assumed to be greater than the reaction force FR. In other words, the electric motor 1 in the third embodiment is, for example, a high-speed rotating motor. In such an electric motor 1, it is preferable to form the pin hole 12 such that the longest line segment R1a (see Figure 3A, etc.) of the pin hole 12 extends in the circumferential direction of the rotor 10, as shown in Figure 5B.
[0030] If the centrifugal force FC is greater than the reaction force FR, the pin 20 may move radially around the rotor 10 when the motor 1 is driven, potentially resulting in insufficient coupling between the multiple magnetic plates 11. 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 radially even when the motor 1 is driven, and as a result, the motor 1 can be driven stably.
[0031] Figure 6 is a radial section cross-sectional view of a rotor according to a fourth embodiment of the present invention, and is similar to Figures 5A and 5B. In the fourth embodiment, the centrifugal force FC and the reaction force FR are assumed to be approximately equal to each other. In Figure 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 Figure 6, the pin holes 12e, 12g, and 12i are inclined clockwise with respect to the radial direction of the rotor 10, and the pin holes 12f and 12h are inclined counterclockwise with respect to the radial direction of the rotor 10. In other words, in Figure 6, the clockwise inclined pin holes 12e, 12g, and 12i and the counterclockwise inclined pin holes 12f and 12h are arranged alternately.
[0032] In this configuration, when the electric motor 1 is driven, the pin 20 does not move in either the radial or circumferential direction of the rotor 10, and as a result, the electric motor 1 can be driven stably.
[0033] Furthermore, in Figure 6, it is preferable that 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. The same applies to the counterclockwise or clockwise inclination angles of the other pin holes. In this case, the electric motor 1 can be driven even more stably.
[0034] Furthermore, Figure 7A is a radial partial cross-sectional view of the rotor based on another modification of the fourth embodiment, and Figure 7B is a radial partial cross-sectional view of the rotor based on yet another modification of the fourth embodiment. Figures 7A and 7B are similar to Figures 5A and 5B, and in these drawings as well, the centrifugal force FC and the reaction force FR are assumed to be approximately equal to each other.
[0035] In Figure 7A, multiple pin holes 12j, 12k, 12l, 12m, 12n, 12o, and 12p are formed at equal intervals in the circumferential direction of the rotor 10. As shown in the figure, 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, the counterclockwise inclined pin holes 12k, 12l, 12o, and 12p and the clockwise inclined pin holes 12j, 12m, and 12n are arranged every two. It is clear that even in this case, the same effect as described above can be obtained. Alternatively, the counterclockwise inclined pin holes and the clockwise inclined pin holes may be arranged every multiple (three or more) of each other.
[0036] In Figure 7B, multiple pin holes 12q, 12r, 12s, 12t, 12u, 12v, and 12w are formed at equal intervals in the circumferential direction of the rotor 10. As shown in the figure, pin holes 12s and 12w are inclined clockwise with respect to the radial direction of the rotor 10. Furthermore, pin holes 12q, 12r, 12t, 12u, and 12v are inclined counterclockwise with respect to the radial direction of the rotor 10. Therefore, pin holes 12q, 12r, 12t, 12u, and 12v that are inclined counterclockwise and pin holes 12s and 12w that are inclined clockwise are arranged randomly. In other words, some of the pin holes are inclined counterclockwise, and the remaining pin holes are inclined clockwise. Preferably, the number of pin holes inclined counterclockwise and the number of pin holes inclined clockwise are approximately equal. It is clear that the same effects as described above can be obtained with such a configuration.
[0037] Figure 8A is a radial partial cross-sectional view of a rotor according to the fifth embodiment of the present invention, Figure 8B is another radial partial cross-sectional view of a rotor according to the fifth embodiment of the present invention, and Figure 8C is an axial partial cross-sectional view of a rotor according to the fifth embodiment of the present invention.
[0038] In Figure 8A, multiple pinholes 12 are formed at equal intervals in the circumferential direction of the magnetic plate 11A. In Figure 8B, multiple pinholes 12' are also formed at equal intervals in the circumferential direction of the magnetic plate 11B. However, the multiple pinholes 12' in Figure 8B are positioned radially outward compared to the multiple pinholes 12 shown in Figure 8A. Note that the cross-section of the pinholes 12 in the fifth embodiment does not need to have twofold symmetry; the cross-section of the pinholes 12 in the fifth embodiment may be circular.
[0039] As shown in Figure 8C, multiple magnetic plates 11B are arranged above and below the rotor 10. Multiple magnetic plates 11A are arranged between the multiple magnetic plates 11B on the upper side and the multiple magnetic plates 11B on the lower side. As a result, pin holes 12x with stepped inner surfaces are formed.
[0040] As shown in Figure 8C, when the pin 20 is curved in a roughly C-shape, the curved portion 21 of the pin 20 conforms to the stepped portion of the pin hole 12x. In other words, in the fifth embodiment, the positions of the multiple through holes in the magnetic plates 11A and 11B are different from each other according to the curved portion 21 of the pin 20. With this configuration, the frictional resistance when pressing the pin 20 into the pin hole 12x is reduced, and the pin 20 can be easily pressed in. For this reason, the same effects as described above can be obtained.
[0041] The number of magnetic plates 11B above and below the rotor 10, as well as the number of multiple magnetic plates 11A, shall be appropriately changed according to the shape of the curved portion 21 of the pin 20. Furthermore, the number of magnetic plates 11B above or below the rotor 10 may be zero. Additionally, using three or more types of magnetic plates with different through-hole positions to form multiple steps is included within the scope of the fifth embodiment.
[0042] Thus, in all embodiments of the present invention, the pinhole 12 has a shape that fits the curved portion 21 of the pin 20 / a shape that absorbs the curved portion 21. Therefore, because of the pinhole 12, when the pin 20 is press-fitted into the pinhole 12, the contact area between the pin 20 and the rotor 10 can be reduced, thereby lowering the frictional resistance. Consequently, the pin 20 can be easily press-fitted into the pinhole 12, and the multiple magnetic plates 11 can be firmly bonded together. As a result, the production efficiency of the rotor 10 can be improved.
[0043] Furthermore, the core in the above-described embodiment may be applied to electromagnetic devices other than electric motors, such as reactors or transformers, and even in such cases, it is still within the scope of the present invention.
[0044] While embodiments of this disclosure have been described in detail, this disclosure is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, or partially deleted in various ways, without departing from the spirit of the invention or the idea and intent of the invention derived from the claims and their equivalents. For example, the order of operations and processes in the embodiments described above are provided as examples only and are not limited thereto. [Explanation of symbols]
[0045] 1 electric motor 5. Shaft section 7, 8 Bearings 9 Stator (core) 10 rotors (cores) 11, 11A, 11B Magnetic plates (core plates) 12, 12a~12x pin holes 20, 20' pin 21 Curved section R1a~R1d Longest line segment Shortest line segment from R2a to R2d
Claims
1. In the core of an electric motor, Multiple pin holes are formed on the end face of the core. Furthermore, it comprises a plurality of pins to be 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, A core in which at least one of the plurality of pin holes into which the at least one pin is inserted is formed to accommodate the curved portion of the at least one pin.
2. The core according to claim 1, wherein the cross-section of the at least one pin hole in the radial direction of the core has twofold symmetry.
3. The core according to claim 2, wherein the cross-section is selected from elliptical, oblong, rectangular, or elongated hexagonal.
4. The core according to claim 1, wherein the cross-section of each of the plurality of pins is annular.
5. The core according to claim 2, wherein, if the centrifugal force acting on the core is smaller than the reaction force of the torque acting on the core, the longest line segment connecting the center of the cross-section of at least one pin hole and the edge of the cross-section over the longest distance is positioned in the radial direction of the core.
6. The core according to claim 2, wherein, if the centrifugal force acting on the core is greater than the reaction force of the torque acting on the core, the longest line segment connecting the center of the cross-section of at least one pin hole and the edge of the cross-section over the longest distance is arranged in the circumferential direction of the core.
7. The core according to claim 2, wherein, when the centrifugal force acting on the core is equal to the reaction force of the torque acting on the core, the longest line segment connecting the center of the cross-section of some of the pin holes of the at least one pin hole to the edge of the cross-section over the longest distance is arranged to be inclined clockwise with respect to the radial direction of the core, and the longest portion of the remaining pin hole of the at least one pin hole is arranged to be inclined counterclockwise with respect to the radial direction of the core.
8. The core according to claim 7, wherein the angle of inclination of the longest line segment of the cross-section of some of the pin holes in a clockwise direction relative to the radial direction of the core is equal to the angle of inclination of the longest line segment of the remaining pin holes in a counterclockwise direction relative to the radial direction of the core.
9. The core according to claim 7 or 8, wherein the aforementioned pin holes and the remaining pin holes are arranged every other pin hole or every other pin hole.
10. The aforementioned core is formed by stacking multiple core plates, Each of the aforementioned multiple core plates has a plurality of through holes corresponding to the plurality of pin holes, The multiple through holes in the multiple core plates are aligned with each other to form the multiple 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 according to the curved portion of at least one pin.