Magnetic core, rotary electric machine, and brushless motor

Abstract

This magnetic core is used for a rotary electric machine and comprises: a core back portion; and a teeth portion including a teeth body extending in a first direction from the core back portion and a teeth tip provided on a tip of the teeth body in the first direction. When a magnetic core is mounted in a rotary electric machine, the position of the geometric center of the teeth portion is different from the position of the geometric center of the core back portion in a second direction, which is a direction along a rotational shaft of the rotary electric machine.

Description

Magnetic core, rotating electrical machine and brushless motor

[0001] The present invention relates to a magnetic core used in a rotating electric machine, a rotating electric machine equipped with a magnetic core, and a brushless motor equipped with a magnetic core.

[0002] A known example of a conventional invention related to a magnetic core is the magnetic core described in Patent Document 1. The magnetic core described in Patent Document 1 includes teeth extending from the inner peripheral surface of a cylindrical yoke extending in a direction along the rotation axis in a direction opposite to the radial direction of the yoke, or teeth extending from the outer peripheral surface of a cylindrical yoke extending in a direction along the rotation axis in a radial direction of the yoke. Here, the rotation axis is the rotation axis of a rotating electric machine when the magnetic core is incorporated into the rotating electric machine. The teeth have tooth main bodies around which coils are wound and tooth tip portions that protrude from the tooth main bodies in a direction along the rotation axis and in a circumferential direction of the yoke.

[0003] JP 2017-060395 A

[0004] However, there is a demand for the magnetic core described in Patent Document 1 to generate a thrust force in a direction along the rotation axis.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a magnetic core, a rotating electric machine, and a brushless motor that are capable of generating a thrust force in a direction along the rotation axis.

[0006] A magnetic core according to one embodiment of the present invention is a magnetic core used in a rotating electric machine, and comprises: a core back portion; a teeth portion including a tooth main body portion extending in a first direction from the core back portion; and a tooth tip portion provided at the tip of the tooth main body portion in the first direction; and when the magnetic core is incorporated into the rotating electric machine, the position of the geometric center of the teeth portion differs from the position of the geometric center of the core back portion in a second direction that is a direction along the rotation axis of the rotating electric machine.

[0007] According to the present invention, it is possible to provide a magnetic core, a rotating electric machine, and a brushless motor that are capable of generating a thrust force in a direction along the rotation axis.

[0008] FIG. 1 is a perspective view of the magnetic core 1. FIG. 2 is a cross-sectional view of the magnetic core 1 viewed in the fourth direction DIR4. FIG. 3 is a perspective view of the exterior of a brushless motor 100 using the magnetic core 1. FIG. 4 is an exploded perspective schematic view of the brushless motor 100 using the magnetic core 1. FIG. 5 is a cross-sectional view of a magnetic core 6 according to a comparative example viewed in the fourth direction DIR4. FIG. 6 is a cross-sectional view of an example of magnetic forces F1 and F2 generated between the magnetic core 6 according to the comparative example and a rotor member 22 when the rotor 20 is rotating, viewed in the fourth direction DIR4. FIG. 7 is a cross-sectional view of an example of magnetic forces F1 and F2 generated between the magnetic core 1 and a rotor member 22 when the rotor 20 is rotating, viewed in the fourth direction DIR4. FIG. 8 is a cross-sectional view of the magnetic core 1a viewed in the fourth direction DIR4. FIG. 9 is a perspective view of the magnetic core 1b. FIG. 10 is a cross-sectional view of the magnetic core 1b viewed in the fourth direction DIR4. Fig. 11 is a cross-sectional view of the magnetic core 1b and the bus bar 40 when viewed in the fourth direction DIR4. Fig. 12 is a perspective view of the magnetic core 1c. Fig. 13 is a cross-sectional view of the magnetic core 1c when viewed in the fourth direction DIR4.

[0009] [First embodiment] (Configuration of magnetic core 1) Hereinafter, the configuration of a magnetic core 1 according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view of the magnetic core 1. Fig. 2 is a cross-sectional view of the magnetic core 1 as viewed in a fourth direction DIR4.

[0010] In this specification, directions are defined as follows. The direction in which the tooth main body portion 31 extends is defined as the first direction DIR1. The direction along the rotation axis of the brushless motor 100 when the magnetic core 1 is incorporated into the brushless motor 100 is defined as the second direction DIR2. The orthogonal projection of the first direction DIR1 onto a plane perpendicular to the second direction DIR2 is defined as the third direction DIR3. In this embodiment, the third direction DIR3 is equal to the first direction DIR1. Furthermore, the direction perpendicular to the second direction DIR2 and the third direction DIR3 is defined as the fourth direction DIR4. Note that in this embodiment, the fourth direction DIR4 is also perpendicular to the first direction DIR1 because the third direction DIR3 is equal to the first direction DIR1. However, the first direction DIR1, the second direction DIR2, the third direction DIR3, and the fourth direction DIR4 are directions defined for the purpose of explanation. Therefore, the first direction DIR1, the second direction DIR2, the third direction DIR3, and the fourth direction DIR4 during actual use of the magnetic core 1 do not necessarily have to coincide with the first direction DIR1, the second direction DIR2, the third direction DIR3, and the fourth direction DIR4 in this embodiment.

[0011] The magnetic core 1 is used in a brushless motor 100. The brushless motor 100 is an example of the "rotating electric machine" of the present invention.

[0012] As shown in Fig. 1, the magnetic core 1 includes a core back portion 2 and teeth portions 3. The magnetic core 1 is made of a soft magnetic material. When an external magnetic field is applied to the soft magnetic material, the soft magnetic material is magnetized. When the application of the magnetic field is then stopped, the soft magnetic material loses its magnetization. An example of a material for such a soft magnetic material is iron.

[0013] The magnetic core 1 is a molded body made of soft magnetic powder. That is, each of the core back portion 2 and the teeth portion 3 is a molded body made of soft magnetic powder. The material of the soft magnetic powder includes, for example, iron and a binder. The binder is, for example, a resin. The soft magnetic powder is, for example, a mixture of iron powder and epoxy resin, which is an example of a binder. Such a magnetic core 1 is produced, for example, by press molding. Furthermore, the outer surface of the magnetic core 1 is subjected to an insulating treatment.

[0014] As shown in FIGS. 1 and 2 , the core back portion 2 has a first main surface S1 and a second main surface S2 aligned in the third direction DIR3. The second main surface S2 is positioned further in the third direction DIR3 than the first main surface S1. As shown in FIG. 1 , each of the first main surface S1 and the second main surface S2 has a rectangular shape when viewed in the third direction DIR3. As shown in FIG. 2 , the core back portion 2 has a geometric center GC2. The geometric center GC2 is the position of the arithmetic mean of all points belonging to the core back portion 2. The core back portion 2 has a shape that is plane-symmetric with respect to a plane perpendicular to the second direction DIR2.

[0015] As shown in FIG. 1 , the tooth portion 3 includes a tooth main body portion 31 and a tooth tip portion 32. As shown in FIG. 2 , the tooth portion 3 has a geometric center GC3. The geometric center GC3 is the position of the arithmetic mean taken over all points belonging to the tooth portion 3. The tooth main body portion 31 extends from the core back portion 2 in the first direction DIR1. More specifically, the tooth main body portion 31 extends from the second principal surface S2 in the first direction DIR1. In this embodiment, the first direction DIR1 is perpendicular to the second direction DIR2. Therefore, the third direction DIR3 is equal to the first direction DIR1. The tooth main body portion 31 has a rectangular parallelepiped shape. The tooth main body portion 31 has a geometric center GC31. The geometric center GC31 is the position of the arithmetic mean taken over all points belonging to the tooth main body portion 31. The tooth main body portion 31 has a shape that is plane-symmetrical with respect to a plane perpendicular to the second direction DIR2.

[0016] 1, the tooth main body portion 31 has a first end E1 and a second end E2, which are opposite ends in the second direction DIR2. The first end E1 is positioned further in the second direction DIR2 than the second end E2. The second direction DIR2 is a direction along the rotation axis of the brushless motor 100 when the magnetic core 1 is incorporated into the brushless motor 100, as shown in FIGS.

[0017] As shown in FIGS. 1 and 2 , the tooth tip portions 32 have a third principal surface S3 and a fourth principal surface S4 aligned in the third direction DIR3. The fourth principal surface S4 is located further in the third direction DIR3 than the third principal surface S3. As shown in FIG. 1 , each of the third principal surface S3 and the fourth principal surface S4 has a rectangular shape when viewed in the third direction DIR3. As shown in FIG. 2 , the tooth tip portions 32 have a geometric center GC32. The geometric center GC32 is the position of the arithmetic mean of all points belonging to the tooth tip portions 32. Furthermore, the tooth tip portions 32 have a shape that is plane-symmetric with respect to a plane perpendicular to the second direction DIR2.

[0018] 1, each tooth tip portion 32 has a third end E3 and a fourth end E4, which are opposite ends in the second direction DIR2. The third end E3 is located further in the second direction DIR2 than the fourth end E4. As shown in FIG. 1, each tooth tip portion 32 is provided at the tip of the tooth main body 31 in the first direction DIR1.

[0019] 1, the outer edge O2 of the core back portion 2 as viewed in the third direction DIR3 surrounds the outer edge O31 of the tooth main body portion 31 as viewed in the third direction DIR3. Furthermore, the outer edge O32 of the tooth tip portion 32 as viewed in the third direction DIR3 surrounds the outer edge O31 of the tooth main body portion 31 as viewed in the third direction DIR3. Furthermore, the length of the tooth main body portion 31 in the second direction DIR2 is uniform in the third direction DIR3 as shown in FIG.

[0020] 2 , the distance D1 in the second direction DIR2 between the first end E1 of the tooth main body 31 and the geometric center GC2 of the core back portion 2 is equal to the distance D2 in the second direction DIR2 between the second end E2 of the tooth main body 31 and the geometric center GC2 of the core back portion 2. Accordingly, the position PGC31 of the geometric center GC31 of the tooth main body 31 in the second direction DIR2 is equal to the position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2.

[0021] 2 , the distance D3 in the second direction DIR2 between the third ends E3 of the tooth tip portions 32 and the geometric center GC2 of the core back portion 2 is smaller than the distance D4 in the second direction DIR2 between the fourth ends E4 of the tooth tip portions 32 and the geometric center GC2 of the core back portion 2. Accordingly, the geometric center GC2 of the core back portion 2 is located further in the second direction DIR2 than the geometric center GC32 of the tooth tip portions 32. That is, the position PGC32 of the geometric center GC32 of the tooth tip portions 32 in the second direction DIR2 is different from the position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2. As a result, the geometric center GC2 of the core back portion 2 is located further in the second direction DIR2 than the geometric center GC3 of the tooth portion 3. That is, in the second direction DIR2, the position PGC3 of the geometric center GC3 of the tooth portion 3 is different from the position PGC2 of the geometric center GC2 of the core back portion 2. More specifically, the geometric center GC2 of the core back portion 2 is located further in the second direction DIR2 than the geometric center GC3 of the tooth portion 3. Therefore, the magnetic core 1 does not have a plane-symmetrical shape with respect to a plane perpendicular to the second direction DIR2. Note that the magnetic core 1 has a plane-symmetrical shape with respect to a plane perpendicular to the fourth direction DIR4.

[0022] Here, the line connecting the geometric centers of the cross sections of the tooth main body 31 perpendicular to the third direction DIR3 is defined as the first line L1. The geometric center of the cross section of the tooth main body 31 perpendicular to the third direction DIR3 is the position of the arithmetic mean taken over all points belonging to the cross section of the tooth main body 31 perpendicular to the third direction DIR3. In this embodiment, the first line L1 is a straight line as shown in FIG. 2 . In addition, in this embodiment, the direction in which the first line L1 extends is parallel to the third direction DIR3 and perpendicular to the second direction DIR2. That is, the position of the first line L1 at the tip of the tooth main body 31 in the first direction DIR1 is equal to the position of the first line L1 at the end of the tooth main body 31 opposite to the tip in the second direction DIR2.

[0023] (Configuration of Brushless Motor 100) The configuration of brushless motor 100 according to the first embodiment of the present invention will be described below with reference to the drawings. Fig. 3 is an external perspective view of brushless motor 100 that uses magnetic core 1. Fig. 4 is an exploded perspective schematic view of brushless motor 100 that uses magnetic core 1. Note that in Fig. 4, reference symbols are assigned only to representative magnetic cores 1, coils 13, and insulating members 14 among the multiple magnetic cores 1, multiple coils 13, and multiple insulating members 14.

[0024] As shown in Fig. 4, brushless motor 100 includes rotor 20 and stator assembly 10. As shown in Fig. 4, stator assembly 10 is disposed around rotor 20 when viewed in second direction DIR2. In other words, brushless motor 100 is an inner rotor type.

[0025] As shown in FIG. 4 , the rotor 20 includes a shaft 21 and a rotor member 22. The shaft 21 has a shape that extends in the second direction DIR2. More specifically, the shaft 21 is cylindrical. The rotor member 22 is cylindrical. The central axes of the shaft 21 and the rotor member 22 are the Z-axis. In other words, the rotation axis of the brushless motor 100 is the Z-axis. Therefore, the second direction DIR2 is a direction along the Z-axis.

[0026] As shown in FIG. 4 , the rotor member 22 includes a soft magnetic material 23 and a hard magnetic material 24. The rotor member 22 is attached to the outer peripheral surface of the shaft 21 in the radial direction centered on the Z axis. More specifically, the soft magnetic material 23 is attached to the outer peripheral surface of the shaft 21 in the radial direction centered on the Z axis. The hard magnetic material 24 is attached to the outer peripheral surface of the soft magnetic material 23 in the radial direction centered on the Z axis. The rotor member 22 is also positioned such that a position PGC22 of the geometric center GC22 of the rotor member 22 in the second direction DIR2 is equal to a position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2. The geometric center GC22 is the position of the arithmetic mean taken over all points belonging to the rotor member 22.

[0027] The soft magnetic body 23 is a soft magnetic body. The hard magnetic body 24 is a hard magnetic body. A hard magnetic body is magnetized when an external magnetic field is applied. Even if the application of the magnetic field is stopped, the hard magnetic body does not lose its magnetization. Such hard magnetic body materials are magnets.

[0028] 4, the stator assembly 10 includes a bearing 11, a housing 12, a plurality of magnetic cores 1, a plurality of coils 13, and a plurality of insulating members 14. That is, the brushless motor 100 includes the magnetic core 1.

[0029] The bearing 11 supports the shaft 21 so that it can rotate in the circumferential direction around the Z-axis. More specifically, as shown in FIG. 4 , the bearing 11 has a first bearing 11a and a second bearing 11b. Each of the first bearing 11a and the second bearing 11b is, for example, a ball bearing. Each of the first bearing 11a and the second bearing 11b is cylindrical. The central axes of the first bearing 11a and the second bearing 11b are aligned with the Z-axis. That is, the central axes of the first bearing 11a and the second bearing 11b coincide with the central axis of the shaft 21.

[0030] 4, the first bearing 11a is positioned further in the second direction DIR2 than the second bearing 11b. The first bearing 11a is positioned further in the second direction DIR2 than the rotor member 22. The second bearing 11b is positioned on the opposite side of the second direction DIR2 than the rotor member 22. The second bearing 11b supports the end of the shaft 21 on the opposite side in the second direction DIR2.

[0031] As shown in Figure 3, the housing 12 has a first housing 12a and a second housing 12b. As shown in Figures 3 and 4, the first housing 12a is cylindrical. The central axis of the first housing 12a is the Z-axis. The first housing 12a is positioned further in the second direction DIR2 than the second housing 12b. The first housing 12a also has an opening OP. As a result, the end of the shaft 21 in the second direction DIR2 protrudes from the opening OP in the second direction DIR2. In other words, the brushless motor 100 is a single-shaft type.

[0032] The first housing 12a supports the first bearing 11a, the plurality of magnetic cores 1, the plurality of coils 13, and the plurality of insulating members 14. The second housing 12b supports the second bearing 11b. The first housing 12a and the second housing 12b are each made of a highly rigid material such as SUS.

[0033] The number of magnetic cores 1, the number of coils 13, and the number of insulating members 14 is nine. Each of the nine coils 13 and each of the nine insulating members 14 is provided corresponding to each of the nine magnetic cores 1. More specifically, if a set includes one magnetic core 1, one coil 13, and one insulating member 14, the nine sets are arranged in the circumferential direction centered on the Z axis. Each set is arranged around the hard magnetic material 24 with a gap therebetween. Note that each set has the same structure. Therefore, a description will be given of one set including one magnetic core 1, one coil 13, and one insulating member 14.

[0034] The magnetic core 1 is magnetized by both the magnetic field generated by the hard magnetic material 24 and the magnetic field generated by the coil 13. As a result, the magnetic core 1 generates a magnetic force that rotates the rotor. Note that, as shown in FIG. 4 , an air gap exists between the magnetic core 1 and the rotor member 22. In this embodiment, the first direction DIR1 is the direction toward the rotation axis of the brushless motor 100 when the magnetic core 1 is incorporated into the brushless motor 100.

[0035] As shown in Fig. 4, the coil 13 is wound around the tooth main body 31 so as to be positioned around the magnetic core 1 when viewed in the radial direction centered on the Z axis. The coil 13 is made of a conductive material such as copper. The coil 13 has a structure in which the surface of a copper wire is covered with an insulating film. The coil 13 generates a magnetic field when a current flows through the coil 13.

[0036] The insulating member 14 is an insulator. As shown in FIG. 4 , the insulating member 14 is disposed between the magnetic core 1 and the coil 13. This electrically insulates the magnetic core 1 and the coil 13. In this embodiment, the insulating member 14 is in the form of a film, but it may also be in the form of a plate. Furthermore, the insulating member 14 may be disposed so that a portion of the insulating member 14 is disposed between the magnetic core 1 and the coil 13. Therefore, the insulating member 14 may be disposed over the entire surface of the coil 13.

[0037] A current is supplied from a power source (not shown) to the coil 13. The rotation of the rotor 20 is controlled by controlling this current.

[0038] [Effect] The magnetic core 1 can generate a thrust force in a direction along the rotation axis. The principle of generating a thrust force in a direction along the rotation axis will be described with reference to the drawings. FIG. 5 is a cross-sectional view of a magnetic core 6 according to a comparative example, viewed in the fourth direction DIR4. FIG. 6 is a cross-sectional view of an example of magnetic forces F1 and F2 generated between the magnetic core 6 according to the comparative example and the rotor member 22 when the rotor 20 is rotating, viewed in the fourth direction DIR4. FIG. 7 is a cross-sectional view of an example of magnetic forces F1 and F2 generated between the magnetic core 1 and the rotor member 22 when the rotor 20 is rotating, viewed in the fourth direction DIR4.

[0039] First, a magnetic core 6 according to a comparative example will be described. Regarding the magnetic core 6 according to the comparative example, only the differences from the magnetic core 1 will be described, and the rest will be omitted. In the magnetic core 6 according to the comparative example, the distance D3 in the second direction DIR2 between the third end E3 of the tooth tip portion 32 and the geometric center GC2 of the core back portion 2 is equal to the distance D4 in the second direction DIR2 between the fourth end E4 of the tooth tip portion 32 and the geometric center GC2 of the core back portion 2, as shown in FIG. 5 . Accordingly, the position PGC32 of the geometric center GC32 of the tooth tip portion 32 in the second direction DIR2 is equal to the position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2. The position PGC31 of the geometric center GC31 of the tooth main body portion 31 and the position PGC32 of the geometric center GC32 of the tooth tip portion 32 in the second direction DIR2 are each equal to the position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2, so the position PGC3 of the geometric center GC3 of the tooth portion 3 in the second direction DIR2 is equal to the position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2. As a result, the position PGC6 of the geometric center GC6 of the magnetic core 6 of the comparative example in the second direction DIR2 is equal to the position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2. The magnetic core 6 of the comparative example also has a shape that is plane-symmetrical with respect to a plane perpendicular to the second direction DIR2.

[0040] When the rotor 20 rotates, magnetic forces F1 and F2 are generated between the magnetic core 6 according to the comparative example and the rotor member 22, as shown in FIG. 6 . The magnetic forces F1 and F2 are Coulomb forces acting between two magnetic charges. When the magnetic poles of the magnetic core 6 according to the comparative example and the magnetic poles of the surface of the rotor member 22 facing the opposite direction to the third direction DIR3 are different from each other, the direction of the magnetic force F1 is the third direction DIR3. On the other hand, when the magnetic poles of the magnetic core 6 according to the comparative example and the magnetic poles of the surface of the rotor member 22 facing the opposite direction to the third direction DIR3 are the same, the direction of the magnetic force F1 is the opposite direction to the third direction DIR3. In either case, the direction of the magnetic force F1 is parallel to the third direction DIR3. That is, the direction of the magnetic force F1 is perpendicular to the second direction DIR2. Therefore, in the magnetic core 6 according to the comparative example, no thrust force is generated along the rotation axis.

[0041] In the magnetic core 1, the position PGC3 of the geometric center GC3 of the teeth portion 3 is different from the position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2. Therefore, the position PGC22 of the geometric center GC22 of the rotor member 22 in the second direction DIR2 is different from the position PGC1 of the geometric center GC1 of the magnetic core 1 in the second direction DIR2. As a result, the directions of the magnetic forces F1 and F2 are not parallel to the third direction DIR3. More specifically, as shown in FIG. 7 , the direction of the magnetic force F1 is parallel to the line connecting the geometric center GC22 of the rotor member 22 and the geometric center GC1 of the magnetic core 1. In this embodiment, the geometric center GC22 of the rotor member 22 is located further in the second direction DIR2 than the geometric center GC1 of the magnetic core 1. As a result, when the magnetic poles of the magnetic core 1 and the surface of the rotor member 22 facing the opposite direction of the third direction DIR3 are different from each other, the magnetic force F1 includes a component in the second direction DIR2. On the other hand, when the magnetic poles of the magnetic core 1 and the surface of the rotor member 22 facing the opposite direction of the third direction DIR3 are the same, the magnetic force F1 includes a component in the opposite direction of the second direction DIR2. In either case, the magnetic force F1 includes a component in the direction along the rotation axis (the second direction DIR2 or the direction opposite to the second direction DIR2). Therefore, the magnetic core 1 can generate a thrust force in the direction along the rotation axis.

[0042] The magnetic core 1 can increase the thrust force in the direction along the rotation axis. More specifically, the Coulomb force is inversely proportional to the square of the distance between two magnetic charges. Furthermore, the magnetic forces F1 and F2 are each a composite of the Coulomb force acting between the rotor member 22 and the tooth tip portions 32, the Coulomb force acting between the rotor member 22 and the tooth main body portion 31, and the Coulomb force acting between the rotor member 22 and the core back portion 2. When the magnetic core 1 is incorporated into the brushless motor 100, of the core back portion 2, the tooth main body portion 31, and the tooth tip portions 32, the tooth tip portions 32 are positioned closest to the rotor member 22. Therefore, with the magnetic core 1, the position PGC32 of the geometric center GC32 of the tooth tip portions 32 in the second direction DIR2 differs from the position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2. As a result, the magnetic core 1 can increase the thrust force in the direction along the rotation axis.

[0043] The magnetic core 1 can ensure regions that overlap with the tooth tip portions 32 in the second direction DIR2 and are located further in the second direction DIR2 than the tooth tip portions 32. More specifically, a distance D3 in the second direction DIR2 between the third ends E3 of the tooth tip portions 32 and the geometric center GC2 of the core back portion 2 is smaller than a distance D4 in the second direction DIR2 between the fourth ends E4 of the tooth tip portions 32 and the geometric center GC2 of the core back portion 2. Therefore, the regions that overlap with the tooth tip portions 32 in the second direction DIR2 and are located further in the second direction DIR2 than the tooth tip portions 32 can be larger than the regions that overlap with the tooth tip portions 32 in the second direction DIR2 and are located in the opposite direction from the tooth tip portions 32 in the second direction DIR2. As a result, with the magnetic core 1, it is possible to secure an area that overlaps with the tooth tip portion 32 when viewed in the second direction DIR2 and is located further in the second direction DIR2 than the tooth tip portion 32.

[0044] The magnetic core 1 makes it easy to wind the coil 13 around the tooth main body 31. More specifically, the position of the first line L1 at the tip of the tooth main body 31 in the first direction DIR1 is equal to the position of the first line L1 at the end of the tooth main body 31 opposite the tip in the second direction DIR2. In other words, the direction in which the first line L1 extends is perpendicular to the second direction DIR2, which is the direction along the rotation axis of the brushless motor 100. Therefore, the magnetic core 1 makes it easy to wind the coil 13 around the tooth main body 31.

[0045] The magnetic core 1 makes it easier to form the magnetic core 1. More specifically, the core back portion 2, the tooth main body portion 31, and the tooth tip portion 32 each have a shape that is plane-symmetrical with respect to a plane perpendicular to the second direction DIR2. Therefore, for example, when manufacturing the magnetic core 1 by press molding, the magnetic core 1 can be manufactured using a die and a punch that each have a shape that is plane-symmetrical with respect to a plane perpendicular to the second direction DIR2. As a result, the magnetic core 1 makes it easier to form the magnetic core 1.

[0046] [Second embodiment] A magnetic core 1a according to a second embodiment of the present invention will be described below with reference to the drawings. Fig. 8 is a cross-sectional view of the magnetic core 1a as viewed in the fourth direction DIR4. Note that, for the magnetic core 1a according to the second embodiment, only the differences from the magnetic core 1 according to the first embodiment will be described, and the rest will be omitted.

[0047] As shown in Figure 8, magnetic core 1a differs from magnetic core 1 in that the position PGC32 in the second direction DIR2 of the geometric center GC32 of the tooth tip portion 32 is equal to the position PGC2 in the second direction DIR2 of the geometric center GC2 of the core back portion 2, and that the position PGC31 in the second direction DIR2 of the geometric center GC31 of the tooth main body portion 31 is different from the position PGC2 in the second direction DIR2 of the geometric center GC2 of the core back portion 2.

[0048] 8 , the distance D3 in the second direction DIR2 between the third ends E3 of the tooth tip portions 32 and the geometric center GC2 of the core back portion 2 is equal to the distance D4 in the second direction DIR2 between the fourth ends E4 of the tooth tip portions 32 and the geometric center GC2 of the core back portion 2. Accordingly, the position PGC32 of the geometric center GC32 of the tooth tip portions 32 in the second direction DIR2 is equal to the position PGC2 of the geometric center GC2 of the core back portion 2 in the second direction DIR2.

[0049] 8 , the distance D1 in the second direction DIR2 between the first end E1 of the tooth main body 31 and the geometric center GC2 of the core back portion 2 is smaller than the distance D2 in the second direction DIR2 between the second end E2 of the tooth main body 31 and the geometric center GC2 of the core back portion 2. Accordingly, the geometric center GC2 of the core back portion 2 is located further in the second direction DIR2 than the geometric center GC31 of the tooth main body 31. As a result, the geometric center GC2 of the core back portion 2 is located further in the second direction DIR2 than the geometric center GC3 of the tooth portion 3. In other words, in the second direction DIR2, the position PGC3 of the geometric center GC3 of the tooth portion 3 is different from the position PGC2 of the geometric center GC2 of the core back portion 2.

[0050] The magnetic core 1a described above also achieves the same effects as the magnetic core 1. Furthermore, with the magnetic core 1a, it is possible to ensure regions that overlap with the tooth main body portions 31 as viewed in the second direction DIR2 but are located further in the second direction DIR2 than the tooth main body portions 31. More specifically, the distance D1 in the second direction DIR2 between the first end E1 of the tooth main body portions 31 and the geometric center GC2 of the core back portion 2 is smaller than the distance D2 in the second direction DIR2 between the second end E2 of the tooth main body portions 31 and the geometric center GC2 of the core back portion 2. Therefore, the regions that overlap with the tooth main body portions 31 as viewed in the second direction DIR2 but are located further in the second direction DIR2 than the tooth main body portions 31 can be larger than the regions that overlap with the tooth main body portions 31 as viewed in the second direction DIR2 but are located in the opposite direction from the tooth main body portions 31 in the second direction DIR2. As a result, with the magnetic core 1a, it is possible to secure an area that overlaps with the tooth main body portion 31 when viewed in the second direction DIR2 and is located further in the second direction DIR2 than the tooth main body portion 31.

[0051] [Third Embodiment] A magnetic core 1b according to a third embodiment of the present invention will be described below with reference to the drawings. Fig. 9 is a perspective view of the magnetic core 1b. Fig. 10 is a cross-sectional view of the magnetic core 1b as viewed in the fourth direction DIR4. Fig. 11 is a cross-sectional view of the magnetic core 1b and the bus bar 40 as viewed in the fourth direction DIR4. Note that with regard to the magnetic core 1b according to the third embodiment, only the differences from the magnetic core 1 according to the first embodiment will be described, and the rest will be omitted.

[0052] 9 and 10, the magnetic core 1b differs from the magnetic core 1 in that the first direction DIR1 is not orthogonal to the second direction DIR2. That is, in this embodiment, the third direction DIR3 is different from the first direction DIR1.

[0053] As shown in FIG. 10 , the position of the first line L1 at the tip of the tooth main body 31 in the first direction DIR1 is offset in the second direction DIR2 from the position of the first line L1 at the end of the tooth main body 31 opposite the tip. Therefore, the tooth main body 31 has a rectangular prism shape. More specifically, in this embodiment, the first line L1 at the tip of the tooth main body 31 in the first direction DIR1 is located in the opposite direction in the second direction DIR2 from the first line L1 at the end of the tooth main body 31 opposite the tip of the tooth main body 31 in the first direction DIR1. Therefore, in this embodiment, the tooth main body 31 does not have a plane-symmetrical shape with respect to a plane perpendicular to the second direction DIR2.

[0054] The magnetic core 1b as described above also achieves the same effect as the magnetic core 1. Furthermore, with the magnetic core 1b, it is possible to secure a region that overlaps with the tip end of the tooth main body portion 31 in the first direction DIR1 as viewed in the second direction DIR2, but is located in the second direction DIR2 or in the opposite direction of the second direction DIR2 from the tip end of the tooth main body portion 31 in the first direction DIR1. More specifically, the position of the first line L1 at the tip of the tooth main body portion 31 in the first direction DIR1 is shifted in the second direction DIR2 from the position of the first line L1 at the end of the tooth main body portion 31 opposite the tip end. In this embodiment, the first line L1 at the tip of the tooth main body portion 31 in the first direction DIR1 is located in the opposite direction of the second direction DIR2 from the first line L1 at the end of the tooth main body portion 31 opposite the tip end of the tooth main body portion 31 in the first direction DIR1. As a result, magnetic core 1b can secure a region that overlaps with the tip ends of tooth main body portions 31 in the first direction DIR1 as viewed in the second direction DIR2 and is located further in the second direction DIR2 than tooth main body portions 31 in the first direction DIR1. As a result, for example, as shown in Fig. 11, wiring members such as busbar 40 can be arranged in a region that overlaps with the tip ends of tooth main body portions 31 in the first direction DIR1 as viewed in the second direction DIR2 and is located further in the second direction DIR2 than the tip ends of tooth main body portions 31 in the first direction DIR1. This allows the length of brushless motor 100 in the second direction DIR2 to be shortened, thereby enabling brushless motor 100 to be made thinner and more compact.

[0055] [First Modification] A magnetic core 1c according to a first modification of the present invention will be described below with reference to the drawings. Fig. 12 is a perspective view of the magnetic core 1c. Fig. 13 is a cross-sectional view of the magnetic core 1c as viewed in the fourth direction DIR4. Note that for the magnetic core 1c according to the first modification, only the differences from the magnetic core 1b according to the third embodiment will be described, and the rest will be omitted.

[0056] As shown in FIGS. 12 and 13, the magnetic core 1c differs from the magnetic core 1b in that the first line L1 is a polygonal line.

[0057] The magnetic core 1c as described above also has the same effect as the magnetic core 1b.

[0058] Other Embodiments The magnetic core according to the present invention is not limited to the magnetic cores 1, 1a to 1c, and can be modified within the scope of the invention. In addition, the structures of the magnetic cores 1, 1a to 1c may be combined arbitrarily.

[0059] The first direction DIR1 may or may not be orthogonal to the second direction DIR2.

[0060] The rotating electric machine may have a structure in which the rotor is rotated by electricity or a structure in which electricity is generated by the rotation of the rotor. In this case, the rotating electric machine may include at least one of the magnetic cores 1, 1a to 1c, and may also include brushes.

[0061] The magnetic cores 1, 1a to 1c may be made by laminating electromagnetic steel sheets, and may be made of any soft magnetic material.

[0062] The outer surfaces of the magnetic cores 1, 1a to 1c do not need to be subjected to an insulating treatment.

[0063] Each of the first main surface S1 and the second main surface S2 of the core back portion 2 does not have to have a rectangular shape when viewed in the third direction DIR3.

[0064] The core back portion 2 does not have to have a shape that is plane-symmetrical with respect to a plane perpendicular to the second direction DIR2.

[0065] The tooth main body 31 does not have to be shaped like a rectangular parallelepiped or a square prism.

[0066] Note that each of the third main surface S3 and the fourth main surface S4 of the tooth tip portion 32 does not have to have a rectangular shape when viewed in the third direction DIR3.

[0067] Note that tooth tip portions 32 do not necessarily have a shape that is plane-symmetrical with respect to a plane perpendicular to second direction DIR2.

[0068] The outer edge O2 of the core back portion 2 as viewed in the third direction DIR3 does not have to surround the outer edge O31 of the tooth main body portion 31 as viewed in the third direction DIR3. Furthermore, the outer edge O32 of the tooth tip portion 32 as viewed in the third direction DIR3 does not have to surround the outer edge O31 of the tooth main body portion 31 as viewed in the third direction DIR3.

[0069] The length of the tooth main body portion 31 in the second direction DIR2 as viewed in the fourth direction DIR4 does not have to be uniform in the third direction DIR3.

[0070] In the magnetic core 1, the distance D1 in the second direction DIR2 between the first end E1 of the tooth main body 31 and the geometric center GC2 of the core back portion 2 may be different from the distance D2 in the second direction DIR2 between the second end E2 of the tooth main body 31 and the geometric center GC2 of the core back portion 2. In addition, in the magnetic core 1, the position PGC31 in the second direction DIR2 of the geometric center GC31 of the tooth main body 31 may be different from the position PGC2 in the second direction DIR2 of the geometric center GC2 of the core back portion 2.

[0071] In the magnetic core 1a, a distance D3 in the second direction DIR2 between the third ends E3 of the tooth tip portions 32 and the geometric center GC2 of the core back portion 2 may be different from a distance D4 in the second direction DIR2 between the fourth ends E4 of the tooth tip portions 32 and the geometric center GC2 of the core back portion 2. In addition, in the magnetic core 1a, a position PGC32 in the second direction DIR2 of the geometric center GC32 of the tooth tip portions 32 may be different from a position PGC2 in the second direction DIR2 of the geometric center GC2 of the core back portion 2.

[0072] The magnetic core 1 does not have to have a shape that is plane-symmetric with respect to a plane orthogonal to the fourth direction DIR4.

[0073] The first line L1 is not limited to a straight line or a polygonal line, but may be a curved line. Furthermore, the first line L1 may include a straight line or a curved line.

[0074] In the magnetic core 1b, the first line L1 at the tip of the tooth main body 31 in the first direction DIR1 may be positioned in the second direction DIR2 further than the first line L1 at the end of the tooth main body 31 on the opposite side to the tip of the tooth main body 31 in the first direction DIR1. In this case, it is possible to secure a region that overlaps with the tip of the tooth main body 31 in the first direction DIR1 as viewed in the second direction DIR2 and is positioned in the opposite direction of the second direction DIR2 from the tooth main body 31 in the first direction DIR1.

[0075] The brushless motor 100 may be an outer rotor type. In this case, the first direction DIR1 is opposite to the direction toward the rotation axis of the brushless motor 100 when the magnetic core 1 is incorporated into the brushless motor 100.

[0076] The brushless motor 100 is not limited to a single-shaft type, but may be, for example, a double-shaft type.

[0077] In the brushless motor 100, the first bearing 11a and the second bearing 11b may each be pressurized by a thrust force generated in a direction along the rotation axis.

[0078] It should be noted that the first bearing 11a and the second bearing 11b are not limited to ball bearings.

[0079] The first housing 12a and the second housing 12b may be made of any material as long as it has high rigidity.

[0080] The number of each of the magnetic cores 1, the coils 13, and the insulating members 14 is not limited to 9. It is sufficient that each of the coils 13 and each of the insulating members 14 is provided corresponding to each of the magnetic cores 1.

[0081] The present invention has the following configuration.

[0082] (1) A magnetic core used in a rotating electric machine, comprising: a core back portion; and a teeth portion including a tooth main body portion extending in a first direction from the core back portion and a tooth tip portion provided at the tip of the tooth main body portion in the first direction, wherein the position of the geometric center of the teeth portion differs from the position of the geometric center of the core back portion in a second direction that is a direction along the rotation axis of the rotating electric machine when the magnetic core is incorporated into the rotating electric machine.

[0083] (2) The magnetic core according to (1), wherein a position of a geometric center of the tooth main body portion in the second direction is different from a position of a geometric center of the core back portion in the second direction.

[0084] (3) The magnetic core according to (1) or (2), wherein a position of a geometric center of the tooth tip portion in the second direction is different from a position of a geometric center of the core back portion in the second direction.

[0085] (4) A magnetic core according to any one of (1) to (3), wherein the tooth main body portion has a first end and a second end which are opposite ends in the second direction, and the distance in the second direction between the first end and the geometric center of the core back portion is smaller than the distance in the second direction between the second end and the geometric center of the core back portion.

[0086] (5) A magnetic core according to any one of (1) to (4), wherein the tooth tip has a third end and a fourth end which are opposite ends in the second direction, and the distance in the second direction between the third end and the geometric center of the core back portion is smaller than the distance in the second direction between the fourth end and the geometric center of the core back portion.

[0087] (6) A magnetic core described in any of (1) to (5), wherein the orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction, a line connecting the geometric centers of cross sections of the tooth main body portion perpendicular to the third direction is defined as a first line, the first line is a straight line, and the position of the first line at the tip of the tooth main body portion and the position of the first line at the end of the tooth main body portion opposite the tip are equal in the second direction.

[0088] (7) A magnetic core described in any of (1) to (5), wherein the orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction, a line connecting the geometric centers of cross sections of the tooth main body portion perpendicular to the third direction is defined as a first line, the first line is a straight line, and the position of the first line at the tip of the tooth main body portion and the position of the first line at the end of the tooth main body portion opposite the tip are shifted in the second direction.

[0089] (8) A magnetic core described in any of (1) to (5), wherein the orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction, a line connecting the geometric centers of cross sections of the tooth main body portion perpendicular to the third direction is defined as a first line, the first line is a broken line, and the position of the first line at the tip of the tooth main body portion and the position of the first line at the end of the tooth main body portion opposite the tip are shifted in the second direction.

[0090] (9) A magnetic core described in any of (1) to (6), wherein the orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction, the core back portion has a shape that is plane-symmetrical with respect to the plane perpendicular to the second direction, the tooth main body portion has a shape that is plane-symmetrical with respect to the plane perpendicular to the second direction, and the tooth tip portion has a shape that is plane-symmetrical with respect to the plane perpendicular to the second direction.

[0091] (10) A magnetic core according to any one of (1) to (9), wherein an orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction, and the length of the tooth main body portion in the second direction is uniform in the third direction.

[0092] (11) The magnetic core according to any one of (1) to (10), wherein the core back portion and the teeth portion are each a molded body formed from soft magnetic powder.

[0093] (12) The magnetic core according to (11), wherein the material of the soft magnetic powder contains iron and resin.

[0094] (13) A rotating electric machine comprising the magnetic core according to any one of (1) to (12).

[0095] (14) A brushless motor including the magnetic core according to any one of (1) to (12).

[0096] DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c, 6: Magnetic core 2: Core back portion 3: Teeth portion 10: Stator assembly 11: Bearing 11a: First bearing 11b: Second bearing 12: Housing 12a: First housing 12b: Second housing 13: Coil 14: Insulating member 20: Rotor 21: Shaft 22: Rotor member 23: Soft magnetic material 24: Hard magnetic material 31: Teeth main body portion 32: Teeth tip portion 40: Bus bar 100: Brushless motor D1, D2, D3, D4: Distance DIR1: First direction DIR2: Second direction DIR3: Third direction DIR4: Fourth direction E1: First end E2: Second end E3: Third end E4: Fourth end GC1, GC2, GC3, GC6, GC22, GC31, GC32: Geometric center L1: First line O2, O31, O32: Outer edge OP: Opening S1: First principal surface S2: Second principal surface S3: Third principal surface S4: Fourth principal surface

Claims

1. A magnetic core for use in a rotating electrical machine, comprising: A core back portion, a teeth portion including a teeth main body portion extending in a first direction from the core back portion and a teeth tip portion provided at a tip of the teeth main body portion in the first direction; It is equipped with a position of a geometric center of the teeth portion is different from a position of a geometric center of the core back portion in a second direction that is a direction along a rotation axis of the rotating electric machine when the magnetic core is assembled in the rotating electric machine; Magnetic core.

2. A position of a geometric center of the tooth main body portion in the second direction is different from a position of a geometric center of the core back portion in the second direction. The magnetic core according to claim 1 .

3. A position of a geometric center of the tooth tip portion in the second direction is different from a position of a geometric center of the core back portion in the second direction. The magnetic core according to claim 1 or 2.

4. The teeth main body portion has a first end and a second end which are opposite ends in the second direction, a distance in the second direction between the first end and the geometric center of the core back portion is smaller than a distance in the second direction between the second end and the geometric center of the core back portion; The magnetic core according to claim 1 or 2.

5. The tooth tip portion has a third end and a fourth end which are opposite ends in the second direction, a distance in the second direction between the third end and a geometric center of the core back portion is smaller than a distance in the second direction between the fourth end and a geometric center of the core back portion; The magnetic core according to claim 1 or 2.

6. An orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction; A line connecting geometric centers of cross sections of the teeth main body portions perpendicular to the third direction is defined as a first line, the first line is a straight line, a position of the first line at the tip of the tooth main body portion and a position of the first line at an end of the tooth main body portion opposite to the tip are equal in the second direction; The magnetic core according to claim 1 or 2.

7. An orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction; A line connecting geometric centers of cross sections of the teeth main body portions perpendicular to the third direction is defined as a first line, the first line is a straight line, a position of the first line at the tip of the tooth main body portion and a position of the first line at an end of the tooth main body portion opposite to the tip are shifted in the second direction. The magnetic core according to claim 1 or 2.

8. An orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction; A line connecting geometric centers of cross sections of the teeth main body portions perpendicular to the third direction is defined as a first line, the first line is a broken line, a position of the first line at the tip of the tooth main body portion and a position of the first line at an end of the tooth main body portion opposite to the tip are shifted in the second direction. The magnetic core according to claim 1 or 2.

9. An orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction; The core back portion has a shape that is plane-symmetrical with respect to a plane perpendicular to the second direction, The tooth main body portion has a shape that is plane-symmetric with respect to a plane perpendicular to the second direction, The tip end portion of the teeth has a shape that is plane-symmetrical with respect to a plane perpendicular to the second direction. The magnetic core according to claim 1 or 2.

10. An orthogonal projection of the first direction onto a plane perpendicular to the second direction is defined as a third direction; The length of the tooth main body portion in the second direction is uniform in the third direction. The magnetic core according to claim 1 or 2.

11. Each of the core back portion and the teeth portion is a molded body formed from soft magnetic powder. The magnetic core according to claim 1 or 2.

12. The material of the soft magnetic powder includes iron and resin; The magnetic core according to claim 11.

13. The magnetic core according to claim 1 or 2 is provided. Rotating electrical machines.

14. The magnetic core according to claim 1 or 2 is provided. Brushless motor.