Rotary electric machine

Abstract

A rotary electrical machine is provided. A rotary electric machine is provided with: a rotor including a magnetized hard magnetic body; and a magnetic core including a tooth portion, in the rotating electrical machine, the tooth portion includes: a tooth main body portion which extends in an inward direction toward a rotation axis of the rotor or in an outward direction opposite to the inward direction, and on which a coil is wound; and a tooth tip section that is formed at the tip of the tooth body section and faces the hard magnetic body, the tooth tip section including a first protruding section that protrudes from the tooth body section in the axial direction along the rotational axis, and the amount of protrusion of the first protruding section from the tooth body section being less than three times the gap width when the hard magnetic body faces the tooth tip section.

Description

Technical Field

[0001] The present invention relates to rotating electrical machines. Background Art

[0002] As an invention related to a conventional rotating electrical machine, for example, a motor described in Patent Document 1 is known. The motor described in Patent Document 1 includes: a shaft that becomes the rotation center when the rotor is rotated relative to the stator; a magnet that is mounted on the rotor and is magnetized alternately to different poles in the circumferential direction centered on the shaft; an iron core that is mounted on the stator and faces the magnet in the radial direction centered on the shaft; a coil that is wound around the iron core; and a magnetic shielding member. The magnetic shielding member shields leakage magnetic flux leaking from the magnet to the coil.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2008-245427

[0004] In the motor described in Patent Document 1, it is desired to increase the back electromotive force generated between both ends of the coil by reducing the magnetic shielding member and increasing the back electromotive force constant. Summary of the invention

[0005] Therefore, an object of the present invention is to provide a rotating electric machine capable of reducing the number of magnetic shielding members and increasing the back electromotive force constant.

[0006] A rotating electrical machine according to one embodiment of the present invention comprises: a rotor including a magnetized hard magnetic body; and a magnetic core including a tooth portion, wherein the tooth portion comprises: a tooth main body portion extending in an inward direction toward the rotation axis of the rotor or in an outward direction opposite to the inward direction and wound with a coil; and a tooth end portion formed at the end of the tooth main body portion and facing the hard magnetic body, the tooth end portion comprising a first protrusion, the first protrusion protruding from the tooth main body portion in an axial direction along the rotation axis, the protrusion amount of the first protrusion from the tooth main body portion being smaller than three times the gap width when the hard magnetic body and the tooth end portion are facing each other.

[0007] According to the present invention, it is possible to provide a rotating electrical machine that can reduce the number of magnetic shielding members and increase the back electromotive force constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 1 is a perspective view of the appearance of the brushless motor 100 .

[0009] Figure 2 It is an exploded schematic perspective view of the brushless motor 100 .

[0010] Figure 3 It is a three-dimensional diagram of the magnetic core 1.

[0011] Figure 4 This is a cross-sectional view of the hard magnetic body 24 and one magnetic core 1 as viewed in a direction perpendicular to the first direction DIR1 and the third direction DIR3.

[0012] Figure 5 It is a cross-sectional view of a hard magnetic body 24 and a magnetic core 6 according to a comparative example, viewed in a direction perpendicular to the first direction DIR1 and the third direction DIR3.

[0013] Figure 6 It is a diagram showing the calculation location of the magnetic flux density.

[0014] Figure 7 This is a diagram showing an example of how the magnetic flux density changes when the first protrusion amount D1 and the second protrusion amount D2 are changed when the offset amount DO is 0.1 mm and the gap width DA is 0.5 mm.

[0015] Figure 8 This is a diagram showing an example of how the magnetic flux density changes when the first protrusion amount D1 and the second protrusion amount D2 are changed when the offset amount DO is 0.2 mm and the gap width DA is 0.5 mm.

[0016] Fig. 9 This is a diagram showing an example of how the back electromotive force constant KE changes when the first protrusion amount D1 and the second protrusion amount D2 are changed when the offset amount DO is 0.2 mm and the gap width DA is 0.5 mm.

[0017] Fig.10 This is a diagram showing an example of how the back electromotive force constant KE changes when the first protrusion amount D1 and the second protrusion amount D2 are changed when the offset amount DO is 0.2 mm and the gap width DA is 0.3 mm. DETAILED DESCRIPTION

[0018] [Implementation Method]

[0019] Hereinafter, a structure of a brushless motor 100 according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 1 is a perspective view of the appearance of the brushless motor 100 . Figure 2 It is an exploded schematic perspective view of the brushless motor 100 . Figure 3 It is a three-dimensional diagram of the magnetic core 1.

[0020] In addition, in this specification, directions are defined as follows. The direction in which the shaft body 21 protrudes from the opening OP to the outside of the housing 12 in the axial direction along the rotation axis of the rotor 20 is defined as a first direction DIR1. The opposite direction of the first direction DIR1 is defined as a second direction DIR2. A direction in the radial direction centered on the rotation axis of the rotor 20, that is, a direction from the geometric center of the tooth tip 32 toward the rotation axis of the rotor 20 when viewed in the first direction DIR1, is defined as a third direction DIR3. A direction in the circumferential direction centered on the rotation axis of the rotor 20, which rotates counterclockwise relative to the rotation axis of the rotor 20 when viewed in the second direction DIR2, is defined as a fourth direction DIR4. In addition, the definitions of directions in this specification are examples.

[0021] like Figure 2 As shown, the brushless motor 100 includes a rotor 20 and a stator assembly 10. When viewed in the first direction DIR1, the stator assembly 10 is disposed around the rotor 20. That is, the brushless motor 100 is an inner rotor type. The brushless motor 100 is an example of a rotary electric machine of the present invention.

[0022] like Figure 2 As shown, the rotor 20 includes a shaft body 21 and a rotor member 22. The shaft body 21 is cylindrical and extends in the first direction DIR1. The rotor member 22 is cylindrical and extends in the first direction DIR1. The central axis of each of the shaft body 21 and the rotor member 22 is the Z axis. That is, the rotation axis of the brushless motor 100 is the Z axis. Therefore, the first direction DIR1 and the second direction DIR2 are directions along the Z axis.

[0023] like Figure 2 As shown, the rotor component 22 has a soft magnetic body 23 and a hard magnetic body 24. The rotor component 22 is mounted on the outer peripheral surface of the shaft body 21 in the radial direction centered on the Z axis. More specifically, the soft magnetic body 23 is mounted on the outer peripheral surface of the shaft body 21 in the radial direction centered on the Z axis. The hard magnetic body 24 is mounted on the outer peripheral surface of the soft magnetic body 23 in the radial direction centered on the Z axis.

[0024] The soft magnetic body 23 is a soft magnetic body. The hard magnetic body 24 is a magnetized hard magnetic body. The hard magnetic body is magnetized when a magnetic field is applied from the outside. Thereafter, even if the application of the magnetic field is stopped, the hard magnetic body does not lose its magnetization.

[0025] like Figure 2 As shown, the stator assembly 10 includes a bearing 11 , a housing 12 , a coil 13 and a magnetic core 1 .

[0026] The bearing 11 supports the shaft body 21 so that it can rotate around the Z axis. Figure 2As shown, the bearing 11 includes a first bearing 11a and a second bearing 11b. The first bearing 11a and the second bearing 11b are each, for example, a ball bearing. The first bearing 11a and the second bearing 11b are each cylindrical and extend in the first direction DIR1. The center axis of each of the first bearing 11a and the second bearing 11b is the Z axis. That is, the center axis of each of the first bearing 11a and the second bearing 11b is consistent with the center axis of the shaft body 21.

[0027] like Figure 2 As shown, the second bearing 11b is located closer to the second direction DIR2 than the first bearing 11a. In addition, the first bearing 11a is located closer to the first direction DIR1 than the rotor member 22. The second bearing 11b is located closer to the second direction DIR2 than the rotor member 22. The second bearing 11b supports the end of the shaft body 21 in the second direction DIR2.

[0028] like Figure 1 As shown in FIG. 1 , the housing 12 includes a first housing 12a and a second housing 12b. Figure 1 and Figure 2 As shown, the first housing 12a is cylindrical. The central axis of the first housing 12a is the Z axis. The first housing 12a is located closer to the first direction DIR1 than the second housing 12b. In addition, the first housing 12a has an opening OP. Thus, the shaft 21 protrudes from the opening OP in the first direction DIR1. That is, the brushless motor 100 is a single-axis type.

[0029] The first housing 12a supports the first bearing 11a, the plurality of cores 1, and the plurality of coils 13. 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.

[0030] The number of coils 13 and the number of cores 1 are each 9. The 9 coils 13 and the 9 cores 1 are arranged in the circumferential direction around the Z axis. The 9 cores 1 are arranged around the hard magnetic body 24 with a gap therebetween.

[0031] like Figure 3 As shown, the magnetic core 1 has a core back 2 and a tooth 3. The tooth 3 has a shape extending from the core back 2 to the third direction DIR3. More specifically, the tooth 3 has: a tooth body 31 extending from the core back 2 to the third direction DIR3 and a tooth end 32 formed at the end of the tooth body 31. Figure 2 As shown, the coil 13 is wound around the tooth body portion 31 .

[0032] The magnetic core 1 is a soft magnetic body. The soft magnetic body is magnetized when a magnetic field is applied from the outside. Thereafter, when the application of the magnetic field is stopped, the soft magnetic body loses its magnetization. The material of such a soft magnetic body is, for example, iron.

[0033] The magnetic core 1 is a molded body formed of soft magnetic powder. That is, the core back 2 and the tooth portion 3 are each a molded body formed 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 a material obtained by mixing, for example, iron powder and an epoxy resin as an example of a binder. Such a magnetic core 1 is made, for example, by press molding. In addition, an insulation treatment is applied to the outer surface of the magnetic core 1 that contacts other components.

[0034] like Figure 3 As shown, the core back 2 has: a first end face E1 and a second end face E2 arranged in the first direction DIR1, an inner main face and an outer main face arranged in the third direction DIR3, and two side faces arranged in the fourth direction DIR4. The first end face E1 is located closer to the first direction DIR1 than the second end face E2. The inner main face is located closer to the third direction DIR3 than the outer main face. In this embodiment, the first end face E1, the second end face E2, and the inner main face are each a flat surface. The outer main face and the two side faces are each a curved surface.

[0035] Figure 4 2 is a cross-sectional view of a hard magnetic body 24 and a magnetic core 1 observed in a direction perpendicular to the first direction DIR1 and the third direction DIR3. Figure 3 and Figure 4 As shown, the tooth terminal portion 32 includes a first protrusion P1 and a second protrusion P2. The first protrusion P1 protrudes from the tooth body portion 31 in the first direction DIR1. The protrusion amount of the first protrusion P1 from the tooth body portion 31 to the first direction DIR1 is defined as a first protrusion amount D1. The second protrusion P2 protrudes from the tooth body portion 31 to the second direction DIR2. The protrusion amount of the second protrusion P2 from the tooth body portion 31 to the second direction DIR2 is defined as a second protrusion amount D2. The first protrusion P1 is located closer to the second direction DIR2 than the first end face E1. In addition, the second protrusion P2 is located closer to the first direction DIR1 than the second end face E2. That is, the first protrusion P1 and the second protrusion P2 are each located between the first end face E1 and the second end face E2 in the first direction DIR1.

[0036] like Figure 2 and Figure 4 As shown in FIG. 1 , the tooth end portion 32 faces the hard magnetic body 24. Figure 4 As shown in FIG. 1 , the inner main surface IS32 of the tooth tip portion 32 in the third direction DIR3 faces the outer peripheral surface OS24 of the hard magnetic body 24 in the third direction DIR3. Figure 2 As shown in FIG. 1 , there is a gap (air gap) between the magnetic core 1 and the rotor member 22. In more detail, as shown in FIG. Figure 4 As shown, there is a gap (air gap) between the inner main surface IS32 of the tooth end portion 32 and the outer peripheral surface OS24 of the hard magnetic body 24. The distance between the tooth end portion 32 and the hard magnetic body 24 is defined as a gap width DA. In the present embodiment, the gap width DA is the distance between the inner main surface IS32 and the outer peripheral surface OS24 in the third direction DIR3. In addition, in the present embodiment, the magnetic center C24 of the hard magnetic body 24 is offset from the magnetic center C1 of the magnetic core 1 in the first direction DIR1. In more detail, the magnetic center C24 of the hard magnetic body 24 is located closer to the first direction DIR1 than the magnetic center C1 of the magnetic core 1. The distance between the magnetic center C24 of the hard magnetic body 24 and the magnetic center C1 of the magnetic core 1 in the first direction DIR1 is defined as an offset DO.

[0037] The coil 13 is made of a conductive material such as copper, for example. The coil 13 has a structure in which the surface of the copper wire is covered with an insulating film. The coil 13 is electrically insulated from the magnetic core 1 by having a structure in which the surface of the copper wire is covered with an insulating film.

[0038] A current is supplied from a power source (not shown) to the coil 13. The coil 13 generates a magnetic field by flowing the current through the coil 13. The magnetic core 1 is magnetized by the magnetic field generated by the hard magnetic body 24 and the magnetic field generated by the coil 13. The rotation of the rotor 20 is controlled by controlling the current supplied from the power source (not shown).

[0039] However, the brushless motor 100 has a structure that can reduce the magnetic shielding member and increase the back electromotive force constant KE. This structure will be described below. Figure 5 It is a cross-sectional view of a hard magnetic body 24 and a magnetic core 6 according to a comparative example, viewed in a direction perpendicular to the first direction DIR1 and the third direction DIR3. Figure 6 It is a diagram showing the calculation location of the magnetic flux density. Figure 7 This is a diagram showing an example of how the magnetic flux density changes when the first protrusion amount D1 and the second protrusion amount D2 are changed when the offset amount DO is 0.1 mm and the gap width DA is 0.5 mm. Figure 8 This is a diagram showing an example of how the magnetic flux density changes when the first protrusion amount D1 and the second protrusion amount D2 are changed when the offset amount DO is 0.2 mm and the gap width DA is 0.5 mm. Fig. 9 This is a diagram showing an example of how the back electromotive force constant KE changes when the first protrusion amount D1 and the second protrusion amount D2 are changed when the offset amount DO is 0.2 mm and the gap width DA is 0.5 mm. Fig.101 is a diagram showing an example of how the back electromotive force constant KE changes when the first protrusion amount D1 and the second protrusion amount D2 are changed when the offset amount DO is 0.2 mm and the gap width DA is 0.3 mm. Figure 7 to Figure 10 This is the result of computer simulation. In addition, regarding the magnetic core 6 according to the comparative example, only the parts that are different from the magnetic core 1 will be described, and the rest will be omitted.

[0040] First, the magnetic core 6 according to the comparative example will be described. Figure 5 As shown, the magnetic core 6 according to the comparative example is different from the magnetic core 1 in that the tooth tip portion 32 does not include the first protrusion P1 and the second protrusion P2. That is, the tooth tip portion 32 does not protrude from the tooth body portion 31 in the first direction DIR1. In addition, the tooth tip portion 32 does not protrude from the tooth body portion 31 in the second direction DIR2.

[0041] like Figure 5 As shown, the magnetic center C24 of the hard magnetic body 24 is located closer to the first direction DIR1 than the magnetic center C1 of the magnetic core 1. Therefore, the leakage magnetic flux B1 leaked from the hard magnetic body 24 to the area located closer to the first direction DIR1 than the tooth body 31 is greater than the leakage magnetic flux B2 leaked from the hard magnetic body 24 to the area located closer to the second direction DIR2 than the tooth body 31. Due to the difference between the leakage magnetic flux B1 and the leakage magnetic flux B2, the hard magnetic body 24 is subjected to a force in the axial direction along the Z axis. This force generates noise and vibration in the brushless motor having the magnetic core 6 involved in the comparative example.

[0042] Therefore, the inventors of the present application have found that if the tooth end portion 32 includes a first protrusion P1 and a second protrusion P2, the difference between the leakage magnetic flux B1 and the leakage magnetic flux B2 becomes smaller, and the noise and vibration generated in the brushless motor 100 can be reduced. In order to confirm the research results, the inventors of the present application performed the computer simulation shown below. In addition, as mentioned above, the first protrusion amount D1 is the protrusion amount of the first protrusion P1 from the tooth body portion 31 to the first direction DIR1. In addition, as mentioned above, the second protrusion amount D2 is the protrusion amount of the second protrusion P2 from the tooth body portion 31 to the second direction DIR2. In addition, as mentioned above, the gap width DA is the distance between the inner main surface IS32 and the outer peripheral surface OS24 in the third direction DIR3.

[0043] The inventors of the present application calculated how the magnetic flux density changes when the first protrusion amount D1 and the second protrusion amount D2 are changed. The average value of the magnetic flux density in the first region A1 is defined as the first direction side magnetic flux density B1AVE. In addition, the average value of the magnetic flux density in the second region A2 is defined as the second direction side magnetic flux density B2AVE. In addition, the first region A1 and the second region A2 are hypothetical regions that are symmetrical to each other with respect to a plane that is orthogonal to the first direction DIR1 and includes the center of the magnetic core 1. In addition, as Figure 6 As shown, the first region A1 is located closer to the tooth main body portion 31 in the first direction DIR1 . The second region A2 is located closer to the tooth main body portion 31 in the second direction DIR2 .

[0044] In addition, Figure 7 to Figure 10 In the example, when the first protrusion amount D1 and the second protrusion amount D2 are 0 mm, the core is the core 6 according to the comparative example. In the example, when the first protrusion amount D1 and the second protrusion amount D2 are larger than 0 mm, the core is the core 1.

[0045] according to Figure 7 , when the offset DO is 0.1 mm and the gap width DA is 0.5 mm, the larger the first protrusion D1 and the second protrusion D2, the smaller the difference (B1AVE-B2AVE) between the first direction side magnetic flux density B1AVE and the second direction side magnetic flux density B2AVE. Therefore, the larger the first protrusion D1 and the second protrusion D2, the smaller the noise and vibration generated in the brushless motor 100 can be. As a result, according to the brushless motor 100, the noise and vibration generated by the brushless motor can be reduced.

[0046] according to Figure 8 , when the offset DO is 0.2 mm and the gap width DA is 0.5 mm, the larger the first protrusion D1 and the second protrusion D2, the smaller the difference (B1AVE-B2AVE) between the first direction side magnetic flux density B1AVE and the second direction side magnetic flux density B2AVE. Therefore, the larger the first protrusion D1 and the second protrusion D2, the smaller the noise and vibration generated in the brushless motor 100. As a result, according to the brushless motor 100, the noise and vibration generated by the brushless motor can be reduced.

[0047] As described above, brushless motor 100 can reduce noise and vibration generated by the brushless motor without requiring a magnetic shielding member for shielding leakage magnetic flux from hard magnetic body 24 to coil 13 .

[0048] In addition, the inventors of the present application have found that if the tooth end portion 32 includes the first protrusion P1 and the second protrusion P2, the back electromotive force constant KE changes in accordance with the changes in the first protrusion amount D1 and the second protrusion amount D2. The inventors of the present application have calculated the change pattern of the back electromotive force constant KE when the first protrusion amount D1 and the second protrusion amount D2 are changed. In addition, the back electromotive force constant KE is a constant obtained by dividing the back electromotive force generated between the two ends of the coil 13 by the angular velocity of the rotor 20.

[0049] according to Fig. 9 , when the offset DO is 0.2 mm and the gap width DA is 0.5 mm, within the range of 0 mm ≤ the first protrusion D1 and the second protrusion D2 ≤ 0.6 mm, the larger the first protrusion D1 and the second protrusion D2 are, the larger the back electromotive force constant KE is. In addition, within the range of 0.6 mm < the first protrusion D1 and the second protrusion D2 ≤ 2 mm, the larger the first protrusion D1 and the second protrusion D2 are, the smaller the back electromotive force constant KE is. In addition, the back electromotive force constant KE within the range of 0 mm < the first protrusion D1 and the second protrusion D2 < 1.5 mm (= 3 times the gap width DA) is greater than the back electromotive force constant KE in the case where the first protrusion D1 and the second protrusion D2 are 0 mm (in the case of the brushless motor with the magnetic core 6 involved in the comparative example). Therefore, if the first protrusion D1 and the second protrusion D2 are smaller than 3 times the gap width DA, the back electromotive force constant KE can be increased.

[0050] according to Fig.10 , when the offset DO is 0.2 mm and the gap width DA is 0.3 mm, within the range of 0 mm ≤ the first protrusion D1 and the second protrusion D2 ≤ 0.4 mm, the larger the first protrusion D1 and the second protrusion D2 are, the larger the back electromotive force constant KE is. In addition, within the range of 0.4 mm < the first protrusion D1 and the second protrusion D2 ≤ 0.8 mm, the larger the first protrusion D1 and the second protrusion D2 are, the smaller the back electromotive force constant KE is. In addition, the back electromotive force constant KE within the range of 0 mm < the first protrusion D1 and the second protrusion D2 < 0.9 mm (= 3 times the gap width DA) is greater than the back electromotive force constant KE in the case where the first protrusion D1 and the second protrusion D2 are 0 mm (in the case of the brushless motor with the magnetic core 6 involved in the comparative example). Therefore, if the first protrusion D1 and the second protrusion D2 are smaller than 3 times the gap width DA, the back electromotive force constant KE can be increased.

[0051] The reason why the back electromotive force constant KE changes in accordance with changes in the first protrusion amount D1 and the second protrusion amount D2 will be described.

[0052] If the first protrusion amount D1 and the second protrusion amount D2 are increased from 0, the magnetic flux generated by the hard magnetic body 24, which is taken from the tooth end portion 32 to the magnetic core 1, increases. In the case where 0mm<the first protrusion amount D1 and the second protrusion amount D2≤the gap width DA, most of the increased magnetic flux passes through the tooth body portion 31, so the back electromotive force constant KE becomes larger. On the other hand, in the case where the gap width DA<the first protrusion amount D1 and the second protrusion amount D2, a part of the increased magnetic flux is directed to the end of the tooth end portion 32 in the first direction DIR1 or the end of the tooth end portion 32 in the second direction DIR2, and surrounds the inside and outside of the tooth end portion 32 near these ends, and does not pass through the tooth body portion 31, so the back electromotive force constant KE becomes smaller.

[0053] [Other embodiments]

[0054] The rotary electric machine according to the present invention is not limited to the brushless motor 100 , and can be modified within the scope of the gist of the present invention.

[0055] In addition, the rotating electrical machine only needs to have a structure that rotates the rotor by electricity or a structure that generates electricity by the rotation of the rotor. The rotating electrical machine includes a brushless motor, a permanent magnet synchronous motor, a permanent magnet synchronous generator, etc. In this case, the rotating electrical machine may also be brushed.

[0056] In addition, the brushless motor 100 may also be an outer rotor type. In this case, the tooth body portion 31 extends from the core back 2 in the opposite direction of the third direction DIR3. In this case, the tooth end portion 32 is also formed at the end of the tooth body portion 31. The back electromotive force constant KE is a constant obtained by dividing the back electromotive force generated between the two ends of the coil 13 by the angular velocity of the rotor 20. Therefore, it can be inferred that even in the case where the brushless motor 100 is an outer rotor type, the back electromotive force constant KE can be increased by making the first protrusion amount D1 and the second protrusion amount D2 smaller than 3 times the gap width DA, as in the aforementioned embodiment. Therefore, in the case where the brushless motor 100 is an outer rotor type, the brushless motor 100 also has the same effect as the inner rotor type.

[0057] Furthermore, when the brushless motor 100 is an outer rotor type, the gap width DA may be the distance between the outer main surface of the tooth tip portion 32 and the outer peripheral surface OS24 of the hard magnetic body 24 in the third direction DIR3 .

[0058] In addition, when the brushless motor 100 is an inner rotor type, the tooth body 31 may not extend from the core back 2 in the third direction DIR3. In this case, the tooth body 31 may extend in the inward direction toward the rotation axis of the rotor 20. The back electromotive force constant KE is a constant obtained by dividing the back electromotive force generated between the two ends of the coil 13 by the angular velocity of the rotor 20. Therefore, it can be inferred that when the brushless motor 100 is an inner rotor type, if the tooth body 31 extends in the inward direction toward the rotation axis of the rotor 20, the back electromotive force constant KE can be increased by making the first protrusion amount D1 and the second protrusion amount D2 smaller than 3 times the gap width DA, as in the above-mentioned embodiment. Therefore, when the brushless motor 100 is an inner rotor type, when the tooth body 31 extends in the inward direction toward the rotation axis of the rotor 20, the same effect as when the tooth body 31 extends from the core back 2 in the third direction DIR3 is achieved.

[0059] In addition, when the brushless motor 100 is an outer rotor type, the tooth body 31 may not extend from the core back 2 in the opposite direction to the third direction DIR3. In this case, the tooth body 31 only needs to extend in the outward direction (the opposite direction to the inward direction of the rotation axis of the rotor 20). The back electromotive force constant KE is a constant obtained by dividing the back electromotive force generated between the two ends of the coil 13 by the angular velocity of the rotor 20. Therefore, it can be inferred that when the brushless motor 100 is an outer rotor type, if the tooth body 31 extends in the outward direction, the back electromotive force constant KE can be increased by making the first protrusion amount D1 and the second protrusion amount D2 smaller than 3 times the gap width DA, as in the above-mentioned embodiment. Therefore, when the brushless motor 100 is an outer rotor type, when the tooth body 31 extends in the outward direction, the same effect as when the tooth body 31 extends from the core back 2 in the third direction DIR3 is achieved.

[0060] In addition, the brushless motor 100 is not limited to a single-shaft type, and the brushless motor 100 may be a dual-shaft type, for example.

[0061] In addition, each of the first bearing 11 a and the second bearing 11 b is not limited to a ball bearing.

[0062] In addition, the material of each of the first housing 12a and the second housing 12b may be a material having high rigidity.

[0063] In addition, the number of coils 13 and the number of magnetic cores 1 are not limited to nine, respectively.

[0064] Alternatively, the magnetic core 1 may be manufactured by laminating electromagnetic steel sheets.

[0065] In addition, both end faces and the inner main face of the core back 2 may be curved surfaces. In addition, both outer main faces and the two side faces of the core back 2 may be flat surfaces.

[0066] In the first direction DIR1, the magnetic center C24 of the hard magnetic body 24 may coincide with the magnetic center C1 of the magnetic core 1. In this case, the offset DO is zero. In this case, the same effect as that of the brushless motor 100 is achieved.

[0067] In addition, the tooth tip portion 32 may include at least one of the first protrusion P1 and the second protrusion P2 .

[0068] In addition, the back electromotive force constant KE may also be an induced voltage constant, a power generation constant, or a torque constant.

[0069] The present invention has the following structure.

[0070] (1) A rotating electrical machine comprising: a rotor including a magnetized hard magnetic body; and a magnetic core including a tooth portion, wherein the tooth portion comprises: a tooth body portion extending in an inward direction toward the rotation axis of the rotor or in an outward direction opposite to the inward direction and wound with a coil; and a tooth tip portion formed at the tip of the tooth body portion and facing the hard magnetic body, the tooth tip portion comprising a first protrusion, the first protrusion protruding from the tooth body portion in an axial direction along the rotation axis, the protrusion amount of the first protrusion from the tooth body portion being smaller than three times the gap width when the hard magnetic body and the tooth tip portion are facing each other.

[0071] (2) In the rotating electrical machinery described in (1), the tooth tip portion includes a second protrusion, which protrudes from the tooth body portion in the axial direction along the rotation axis in the opposite direction to the first protrusion, and the protrusion amount of the second protrusion from the tooth body portion is smaller than 3 times the gap width.

[0072] (3) In the rotating electrical machine described in (1) or (2), the position of the magnetic center of the hard magnetic body is offset from the magnetic center of the magnetic core in the axial direction along the rotation axis.

[0073] (4) In the rotating electrical machine described in (1) or (2), the position of the magnetic center of the hard magnetic body coincides with the magnetic center of the magnetic core in the axial direction along the rotation axis.

[0074] (5) In the rotating electrical machine described in any one of (1) to (4), the magnetic core is a molded body formed of soft magnetic powder.

[0075] Description of Reference Numerals

[0076] 1...magnetic core; 2...back of the core; 3...tooth; 6...magnetic core; 10...stator assembly; 11...bearing; 11a...first bearing; 11b...second bearing; 12...housing; 12a...first housing; 12b...second housing; 13...coil; 20...rotor; 21...shaft; 22...rotor member; 23...soft magnetic body; 24...hard magnetic body; 31...tooth main body; 32...tooth end; 100...brushless motor; A1...first region; A2... The second region; B1, B2...magnetic flux; B1AVE...magnetic flux density on the first direction side; B2AVE...magnetic flux density on the second direction side; C1, C24...magnetic center; D1...first protrusion; D2...second protrusion; DA...gap width; DIR1...first direction; DIR2...second direction; DIR3...third direction; DIR4...fourth direction; DO...offset; E1...first end face; E2...second end face; IS32...inner main surface; KE...back electromotive force constant.

Claims

1. A rotary electric machine comprising: a rotor including a magnetized hard magnetic body; and a magnetic core including a tooth portion, wherein the rotary electric machine is characterized in that: The tooth portion has: a tooth body portion extending in an inward direction toward a rotation axis of the rotor or in an outward direction opposite to the inward direction and having a coil wound therearound; and a tooth terminal portion formed at the terminal end of the tooth main body portion and facing the hard magnetic body, The tooth tip portion includes a first protrusion that protrudes from the tooth body portion in an axial direction along the rotation axis. The amount of protrusion of the first protrusion from the tooth body is smaller than three times the width of a gap when the hard magnetic body and the tooth tip end portion face each other.

2. The rotating electrical machine according to claim 1, characterized in that: The tooth tip portion includes a second protrusion that protrudes from the tooth body portion in an axial direction along the rotation axis in a direction opposite to the first protrusion. The amount of protrusion of the second protrusion from the tooth body is smaller than three times the gap width.

3. The rotating electrical machine according to claim 1 or 2, characterized in that: The position of the magnetic center of the hard magnetic body is offset from the magnetic center of the magnetic core in the axial direction along the rotation axis.

4. The rotating electrical machine according to claim 1 or 2, characterized in that: The position of the magnetic center of the hard magnetic body coincides with the magnetic center of the magnetic core in the axial direction along the rotation axis.

5. The rotating electrical machine according to any one of claims 1 to 4, characterized in that: The magnetic core is a molded body formed of soft magnetic powder.

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