Rotating electric machine

Abstract

This rotating electric machine comprises: a rotor including a magnetized hard magnetic body; and a magnetic body core including a tooth portion. The tooth portion has: a tooth body portion which extends inward toward the rotational axis of the rotor or reversely extends outward and around which a coil is wound; and a tooth end portion which is formed at the end of the tooth body portion and faces the hard magnetic body. The tooth end portion includes a first projection portion that projects from the tooth body portion in the axial direction along the rotational axis, wherein the projection amount of the first projection portion from the tooth body portion is less than three times the width of a gap formed when the hard magnetic body and the tooth end portion face each other.

Description

rotating electrical machines

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

[0002] A known example of a conventional invention relating to a rotating electric machine is the motor described in Patent Document 1. The motor described in Patent Document 1 includes a shaft that serves as the center of rotation when a rotor rotates relative to a stator, a magnet attached to the rotor and magnetized with alternating polarities in the circumferential direction around the axis, an iron core attached to the stator and facing the magnet in the radial direction around the axis, a coil wound around the iron core, and a magnetic shielding member. The magnetic shielding member shields leakage magnetic flux from the magnet to the coil.

[0003] Japanese Patent Application Laid-Open No. 2008-245427

[0004] In the motor described in Patent Document 1, there is a demand for increasing the counter electromotive force generated between both ends of the coil by increasing the counter electromotive force constant while reducing the magnetic shielding member.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a rotating electric machine that can increase the back electromotive force constant while reducing the number of magnetic shielding members.

[0006] A rotating electric machine according to one embodiment of the present invention is a rotating electric machine comprising: a rotor including a magnetized hard magnetic material; and a magnetic core including tooth portions, wherein the tooth portions have: tooth main body portions extending inward toward the rotation axis of the rotor or outward in the opposite direction, and around which coils are wound; and tooth tip portions formed at the tips of the tooth main body portions and facing the hard magnetic material, wherein the tooth tip portions include first protrusions protruding from the tooth main body portion in the axial direction along the rotation axis, and the amount of protrusion of the first protrusions from the tooth main body portions is less than three times the gap width when the hard magnetic material and the tooth tip portions face each other.

[0007] According to the present invention, it is possible to provide a rotating electric machine that can increase the back electromotive force constant while reducing the number of magnetic shielding members.

[0008] FIG. 1 is an external perspective view of the brushless motor 100. FIG. 2 is an exploded perspective schematic view of the brushless motor 100. FIG. 3 is a perspective view of the magnetic core 1. FIG. 4 is a cross-sectional view of the hard magnetic material 24 and one magnetic core 1 viewed in a direction perpendicular to the first direction DIR1 and the third direction DIR3. FIG. 5 is a cross-sectional view of the hard magnetic material 24 and one comparative magnetic core 6 viewed in a direction perpendicular to the first direction DIR1 and the third direction DIR3. FIG. 6 is a diagram showing calculation locations of magnetic flux density. FIG. 7 is a diagram showing an example of changes in magnetic flux density 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. FIG. 8 is a diagram showing an example of changes in magnetic flux density 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 is a graph showing an example of how the counter 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. 10 is a graph showing an example of how the counter 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.

[0009] [Embodiment] The configuration of a brushless motor 100 according to an embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is an external perspective view of the brushless motor 100. Fig. 2 is an exploded perspective schematic view of the brushless motor 100. Fig. 3 is a perspective view of a magnetic core 1.

[0010] Furthermore, in this specification, directions are defined as follows. Among the axial directions along the rotation axis of the rotor 20, the direction in which the shaft 21 protrudes from the opening OP to the outside of the housing 12 is defined as a first direction DIR1. The opposite direction of the first direction DIR1 is defined as a second direction DIR2. One of the radial directions centered on the rotation axis of the rotor 20, which is the direction from the geometric center of the tooth tip portions 32 toward the rotation axis of the rotor 20 as viewed in the first direction DIR1, is defined as a third direction DIR3. Among the circumferential directions centered on the rotation axis of the rotor 20, the counterclockwise direction with respect to the rotation axis of the rotor 20 as viewed in the second direction DIR2 is defined as a fourth direction DIR4. Note that the definitions of directions in this specification are merely examples.

[0011] As shown in Fig. 2, brushless motor 100 includes rotor 20 and stator assembly 10. Stator assembly 10 is disposed around rotor 20 when viewed in first direction DIR1. In other words, brushless motor 100 is an inner rotor type. Brushless motor 100 is an example of a rotating electric machine of the present invention.

[0012] As shown in Figure 2, the rotor 20 includes a shaft 21 and a rotor member 22. The shaft 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 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 first direction DIR1 and the second direction DIR2 are each a direction along the Z-axis.

[0013] 2, the rotor member 22 has a soft magnetic material 23 and a hard magnetic material 24. The rotor member 22 is attached to the outer circumferential 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 circumferential surface of the shaft 21 in the radial direction centered on the Z axis. The hard magnetic material 24 is attached to the outer circumferential surface of the soft magnetic material 23 in the radial direction centered on the Z axis.

[0014] The soft magnetic material 23 is a soft magnetic material. The hard magnetic material 24 is a magnetized hard magnetic material. The hard magnetic material is magnetized when an external magnetic field is applied. After that, even if the application of the magnetic field is stopped, the hard magnetic material does not lose its magnetization.

[0015] As shown in FIG. 2 , the stator assembly 10 includes a bearing 11 , a housing 12 , a coil 13 and a magnetic core 1 .

[0016] 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. 2 , 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 has a cylindrical shape extending in the first direction DIR1. 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.

[0017] 2, the second bearing 11b is positioned further in the second direction DIR2 than the first bearing 11a. The first bearing 11a is positioned further in the first direction DIR1 than the rotor member 22. The second bearing 11b is positioned further in the second direction DIR2 than the rotor member 22. The second bearing 11b supports the end of the shaft 21 in the second direction DIR2.

[0018] As shown in FIG. 1, the housing 12 has a first housing 12a and a second housing 12b. As shown in FIGS. 1 and 2, 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 first direction DIR1 than the second housing 12b. The first housing 12a also has an opening OP. This allows the shaft 21 to protrude from the opening OP in the first direction DIR1. In other words, the brushless motor 100 is a single-shaft type.

[0019] The first housing 12a supports the first bearing 11a, the plurality of magnetic 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.

[0020] The number of coils 13 and the number of magnetic cores 1 are each nine. The nine coils 13 and the nine magnetic cores 1 are arranged in the circumferential direction centered on the Z axis. The nine magnetic cores 1 are arranged around the hard magnetic material 24 with a gap therebetween.

[0021] As shown in Fig. 3, the magnetic core 1 has a core back portion 2 and teeth portions 3. The teeth portions 3 have a shape extending from the core back portion 2 in the third direction DIR3. More specifically, the teeth portions 3 have tooth main body portions 31 extending from the core back portion 2 in the third direction DIR3, and tooth tip portions 32 formed at the tips of the tooth main body portions 31. As shown in Fig. 2, the coil 13 is wound around the tooth main body portions 31.

[0022] 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 stopped, the soft magnetic material loses its magnetization. An example of a material for such a soft magnetic material is iron.

[0023] 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, 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, an insulating treatment is applied to the outer surface of the magnetic core 1 that comes into contact with another member.

[0024] As shown in FIG. 3 , the core back portion 2 has a first end face E1 and a second end face E2 aligned in a first direction DIR1, an inner main surface and an outer main surface aligned in a third direction DIR3, and two side surfaces aligned in a fourth direction DIR4. The first end face E1 is positioned further in the first direction DIR1 than the second end face E2. The inner main surface is positioned further in the third direction DIR3 than the outer main surface. In this embodiment, the first end face E1, the second end face E2, and the inner main surface are each flat. The outer main surface and the two side surfaces are each curved.

[0025] FIG. 4 is a cross-sectional view of the hard magnetic material 24 and one magnetic core 1 viewed in a direction perpendicular to the first direction DIR1 and the third direction DIR3. As shown in FIGS. 3 and 4 , the tooth tip portion 32 includes a first protrusion P1 and a second protrusion P2. The first protrusion P1 protrudes from the tooth main body 31 in the first direction DIR1. The amount by which the first protrusion P1 protrudes from the tooth main body 31 in the first direction DIR1 is defined as a first protrusion amount D1. The second protrusion P2 protrudes from the tooth main body 31 in the second direction DIR2. The amount by which the second protrusion P2 protrudes from the tooth main body 31 in the second direction DIR2 is defined as a second protrusion amount D2. The first protrusion P1 is located further in the second direction DIR2 than the first end face E1. The second protrusion P2 is located further in 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.

[0026] As shown in FIGS. 2 and 4 , the tooth tip portions 32 face the hard magnetic material 24. More specifically, the inner main surfaces IS32 of the tooth tip portions 32 in the third direction DIR3 face the outer peripheral surfaces OS24 of the hard magnetic material 24 in the third direction DIR3, as shown in FIG. 4 . Furthermore, as shown in FIG. 2 , an air gap exists between the magnetic core 1 and the rotor member 22. More specifically, as shown in FIG. 4 , an air gap exists between the inner main surfaces IS32 of the tooth tip portions 32 and the outer peripheral surfaces OS24 of the hard magnetic material 24. The distance between the tooth tip portions 32 and the hard magnetic material 24 is defined as a gap width DA. In this embodiment, the gap width DA is the distance in the third direction DIR3 between the inner main surfaces IS32 and the outer peripheral surfaces OS24. In this embodiment, the magnetic center C24 of the hard magnetic material 24 and the magnetic center C1 of the magnetic core 1 are offset in the first direction DIR1. More specifically, the magnetic center C24 of the hard magnetic material 24 is positioned further in the first direction DIR1 than the magnetic center C1 of the magnetic core 1. The distance in the first direction DIR1 between the magnetic center C24 of the hard magnetic material 24 and the magnetic center C1 of the magnetic core 1 is defined as an offset amount DO.

[0027] The coil 13 is made of a conductive material such as copper, and has a structure in which the surface of a copper wire is covered with an insulating coating, so that the coil 13 and the magnetic core 1 are electrically insulated from each other.

[0028] A current is supplied to the coil 13 from a power supply (not shown). When a current flows through the coil 13, the coil 13 generates a magnetic field. 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. The rotation of the rotor 20 is controlled by controlling the current supplied from the power supply (not shown).

[0029] The brushless motor 100 has a structure that can increase the back electromotive force constant KE while reducing the number of magnetic shielding members. This structure is described below. FIG. 5 is a cross-sectional view of the hard magnetic material 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. FIG. 6 is a diagram showing the locations where magnetic flux density is calculated. FIG. 7 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. FIG. 8 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 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. 10 shows an example of the change in the back electromotive force constant KE 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. Note that FIGS. 7 to 10 are the results of computer simulations. 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.

[0030] First, a magnetic core 6 according to a comparative example will be described. The magnetic core 6 according to the comparative example differs from the magnetic core 1 in that the tooth tip portions 32 do not include the first protrusion P1 and the second protrusion P2, as shown in Fig. 5. That is, the tooth tip portions 32 do not protrude from the tooth main body 31 in the first direction DIR1. Furthermore, the tooth tip portions 32 do not protrude from the tooth main body 31 in the second direction DIR2.

[0031] 5, the magnetic center C24 of the hard magnetic body 24 is located further in the first direction DIR1 than the magnetic center C1 of the magnetic core 1. Therefore, leakage flux B1 from the hard magnetic body 24 to a region located further in the first direction DIR1 than the tooth main body 31 is greater than leakage flux B2 from the hard magnetic body 24 to a region located further in the second direction DIR2 than the tooth main body 31. Due to the difference between the leakage flux B1 and the leakage flux B2, the hard magnetic body 24 receives a force in the axial direction along the Z axis. This force causes noise and vibration in a brushless motor equipped with the magnetic core 6 according to the comparative example.

[0032] Therefore, the inventors of the present application discovered that when tooth tip portion 32 includes first protrusion portion P1 and second protrusion portion P2, the difference between leakage magnetic flux B1 and leakage magnetic flux B2 is reduced, thereby reducing noise and vibration generated by brushless motor 100. To confirm this finding, the inventors performed the following computer simulation. As described above, first protrusion amount D1 is the amount of protrusion of first protrusion portion P1 from tooth main body portion 31 in first direction DIR1. As described above, second protrusion amount D2 is the amount of protrusion of second protrusion portion P2 from tooth main body portion 31 in second direction DIR2. As described above, gap width DA is the distance in third direction DIR3 between inner main surface IS32 and outer peripheral surface OS24.

[0033] The inventors of the present application calculated the change in magnetic flux density when the first protrusion amount D1 and the second protrusion amount D2 were changed. The average value of the magnetic flux density in the first region A1 was defined as the first direction magnetic flux density B1AVE. The average value of the magnetic flux density in the second region A2 was defined as the second direction magnetic flux density B2AVE. The first region A1 and the second region A2 are imaginary regions that are perpendicular to the first direction DIR1 and symmetrical to each other with respect to a plane including the center of the magnetic core 1. As shown in FIG. 6 , the first region A1 is located further in the first direction DIR1 than the tooth main body portion 31. The second region A2 is located further in the second direction DIR2 than the tooth main body portion 31.

[0034] 7 to 10, when the first protrusion amount D1 and the second protrusion amount D2 are 0 mm, the magnetic core is the magnetic core 6 according to the comparative example. When the first protrusion amount D1 and the second protrusion amount D2 are greater than 0 mm, the magnetic core is the magnetic core 1.

[0035] 7, when the offset amount DO is 0.1 mm and the gap width DA is 0.5 mm, the greater the first protrusion amount D1 and the second protrusion amount 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 greater the first protrusion amount D1 and the second protrusion amount D2, the smaller the noise and vibration generated by brushless motor 100. As a result, brushless motor 100 can reduce the noise and vibration generated by the brushless motor.

[0036] 8, even when the offset amount DO is 0.2 mm and the gap width DA is 0.5 mm, the greater the first protrusion amount D1 and the second protrusion amount 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 greater the first protrusion amount D1 and the second protrusion amount D2, the smaller the noise and vibration generated by brushless motor 100. As a result, brushless motor 100 can reduce the noise and vibration generated by the brushless motor.

[0037] As described above, the brushless motor 100 does not require a magnetic shielding member for shielding leakage magnetic flux from the hard magnetic body 24 to the coil 13, and can reduce noise and vibration generated by the brushless motor.

[0038] The inventors also discovered that when the tooth tip portions 32 include the first protrusion P1 and the second protrusion P2, the back electromotive force constant KE changes in response to changes in the first protrusion amount D1 and the second protrusion amount D2. The inventors calculated the change in the back electromotive force constant KE when the first protrusion amount D1 and the second protrusion amount D2 are changed. The back electromotive force constant KE is a constant obtained by dividing the back electromotive force generated between both ends of the coil 13 by the angular velocity of the rotor 20.

[0039] 9, when the offset DO is 0.2 mm and the gap width DA is 0.5 mm, the back electromotive force constant KE increases as the first protrusion amount D1 and the second protrusion amount D2 increase in the range of 0 mm≦first protrusion amount D1 and the second protrusion amount D2≦0.6 mm. Furthermore, in the range of 0.6 mm<first protrusion amount D1 and the second protrusion amount D2≦2 mm, the back electromotive force constant KE decreases as the first protrusion amount D1 and the second protrusion amount D2 increase. Furthermore, the back electromotive force constant KE in the range of 0 mm<first protrusion amount D1 and the second protrusion amount D2<1.5 mm (= three times the gap width DA) is greater than the back electromotive force constant KE when the first protrusion amount D1 and the second protrusion amount D2 are 0 mm (in the case of a brushless motor including a magnetic core 6 according to the comparative example). Therefore, if the first protrusion amount D1 and the second protrusion amount D2 are less than three times the gap width DA, the back electromotive force constant KE can be increased.

[0040] 10 , when the offset DO is 0.2 mm and the gap width DA is 0.3 mm, the back electromotive force constant KE increases as the first protrusion amount D1 and the second protrusion amount D2 increase in the range of 0 mm≦first protrusion amount D1 and the second protrusion amount D2≦0.4 mm. Furthermore, in the range of 0.4 mm<first protrusion amount D1 and the second protrusion amount D2≦0.8 mm, the back electromotive force constant KE decreases as the first protrusion amount D1 and the second protrusion amount D2 increase. Furthermore, the back electromotive force constant KE in the range of 0 mm<first protrusion amount D1 and the second protrusion amount D2<0.9 mm (= three times the gap width DA) is greater than the back electromotive force constant KE when the first protrusion amount D1 and the second protrusion amount D2 are 0 mm (in the case of a brushless motor including a magnetic core 6 according to the comparative example). Therefore, if the first protrusion amount D1 and the second protrusion amount D2 are less than three times the gap width DA, the back electromotive force constant KE can be increased.

[0041] The reason why the counter electromotive force constant KE changes in response to changes in the first protrusion amount D1 and the second protrusion amount D2 will be explained.

[0042] As the first protrusion amount D1 and the second protrusion amount D2 are increased from 0, the magnetic flux generated by the hard magnetic material 24 increases, and the magnetic flux that is taken into the magnetic core 1 from the tooth tip portion 32 increases. When 0 mm < 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 main body portion 31, and the back electromotive force constant KE increases. On the other hand, when the gap width DA < the first protrusion amount D1 and the second protrusion amount D2, part of the increased magnetic flux heads toward the tip of the tooth tip portion 32 in the first direction DIR1 or the tip of the tooth tip portion 32 in the second direction DIR2, and circulates inside and outside the tooth tip portion 32 near these tips, without passing through the tooth main body portion 31, and the back electromotive force constant KE decreases.

[0043] Other Embodiments The rotating 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 thereof.

[0044] The rotating electric machine may have a structure in which a rotor is rotated by electricity or a structure in which electricity is generated by the rotation of the rotor. Examples of the rotating electric machine include a brushless motor, a permanent magnet synchronous motor, and a permanent magnet synchronous generator. In this case, the rotating electric machine may be equipped with brushes.

[0045] Note that brushless motor 100 may be an outer rotor type. In this case, tooth main body portion 31 extends from core back portion 2 in the direction opposite to third direction DIR3. Even in this case, tooth tip portion 32 is formed at the tip of tooth main body portion 31. Because back electromotive force constant KE is a constant obtained by dividing the back electromotive force generated between both ends of coil 13 by the angular velocity of rotor 20, even when brushless motor 100 is an outer rotor type, it can be inferred that back electromotive force constant KE can be increased by making first protrusion amount D1 and second protrusion amount D2 less than three times gap width DA, as in the above-described embodiment. Therefore, even when brushless motor 100 is an outer rotor type, the same effect as when brushless motor 100 is an inner rotor type can be achieved.

[0046] In addition, if the brushless motor 100 is an outer rotor type, the gap width DA may be the distance in the third direction DIR3 between the outer main surface of the tooth tip portion 32 and the outer peripheral surface OS24 of the hard magnetic body 24.

[0047] Note that, when brushless motor 100 is an inner rotor type, tooth main body portions 31 do not have to extend in the third direction DIR3 from core back portion 2. In this case, tooth main body portions 31 only need to extend inward toward the rotational axis of rotor 20. Because back electromotive force constant KE is a constant obtained by dividing the back electromotive force generated between both ends of coil 13 by the angular velocity of rotor 20, when brushless motor 100 is an inner rotor type, if tooth main body portions 31 extend inward toward the rotational axis of rotor 20, it can be inferred that, as in the above-described embodiment, back electromotive force constant KE can be increased by making first protrusion amount D1 and second protrusion amount D2 less than three times gap width DA. Therefore, when brushless motor 100 is an inner rotor type, even when tooth main body portions 31 extend inward toward the rotational axis of rotor 20, the same effect as when tooth main body portions 31 extend in the third direction DIR3 from core back portion 2 can be achieved.

[0048] Note that, when brushless motor 100 is an outer rotor type, tooth main body portions 31 do not have to extend from core back portion 2 in the direction opposite to third direction DIR3. In this case, tooth main body portions 31 only need to extend outward (opposite to the inward direction toward the rotation axis of rotor 20). Because back electromotive force constant KE is a constant obtained by dividing the back electromotive force generated between both ends of coil 13 by the angular velocity of rotor 20, when brushless motor 100 is an outer rotor type, if tooth main body portions 31 extend outward, it can be inferred that, as in the above-described embodiment, back electromotive force constant KE can be increased by making first protrusion amount D1 and second protrusion amount D2 less than three times gap width DA. Therefore, when brushless motor 100 is an outer rotor type and tooth main body portions 31 extend outward, the same effect can be achieved as when brushless motor 100 is an inner rotor type and tooth main body portions 31 extend in third direction DIR3 from core back portion 2.

[0049] The brushless motor 100 is not limited to a single-shaft type, but may be, for example, a double-shaft type.

[0050] It should be noted that the first bearing 11a and the second bearing 11b are not limited to ball bearings.

[0051] The first housing 12a and the second housing 12b may be made of any material as long as it has high rigidity.

[0052] The number of coils 13 and the number of magnetic cores 1 are not limited to nine.

[0053] The magnetic core 1 may be made by laminating electromagnetic steel sheets.

[0054] The two end faces and the inner main surface of the core back portion 2 may each be curved. The outer main surface and the two side surfaces of the core back portion 2 may each be flat.

[0055] The magnetic center C24 of the hard magnetic material 24 and the magnetic center C1 of the magnetic core 1 may coincide in the first direction DIR1. In this case, the offset amount DO is zero. In this case, the same effect as that of the brushless motor 100 is achieved.

[0056] The tooth tip portion 32 may include at least one of the first protrusion P1 and the second protrusion P2.

[0057] The counter electromotive force constant KE may be an induced voltage constant, a power generation constant, or a torque constant.

[0058] The present invention has the following configuration.

[0059] (1) A rotating electric machine comprising a rotor including a magnetized hard magnetic material and a magnetic core including teeth, wherein the teeth have: a tooth main body portion extending inward toward the rotation axis of the rotor or outward in the opposite direction, around which a coil is wound; and a tooth tip portion formed at the tip of the tooth main body portion and facing the hard magnetic material, wherein the tooth tip portion includes a first protrusion protruding from the tooth main body portion in the axial direction along the rotation axis, and the protrusion amount of the first protrusion from the tooth main body portion is less than three times the gap width when the hard magnetic material and the tooth tip portion face each other.

[0060] (2) The rotating electric machine described in (1), wherein the tooth tip includes a second protrusion protruding from the tooth main body in an opposite direction to the first protrusion in an axial direction along the rotation axis, and the protrusion amount of the second protrusion from the tooth main body is less than three times the gap width.

[0061] (3) The rotating electric machine according to (1) or (2), wherein the magnetic center of the hard magnetic body and the magnetic center of the magnetic core are misaligned in the axial direction along the rotation axis.

[0062] (4) The rotating electric machine according to (1) or (2), wherein the position of the magnetic center of the hard magnetic body and the magnetic center of the magnetic core coincide in the axial direction along the rotation axis.

[0063] (5) The rotating electric machine according to any one of (1) to (4), wherein the magnetic core is a compact formed from soft magnetic powder.

[0064] 1: Magnetic core 2: Core back portion 3: Teeth portion 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 material 24: Hard magnetic material 31: Teeth main body portion 32: Teeth tip portion 100: Brushless motor A1: First region A2: Second region B1, B2: Magnetic flux B1AVE: First direction magnetic flux density B2AVE: Second direction magnetic flux density C1, C24: Magnetic center D1: First protrusion amount D2: Second protrusion amount DA: Gap width DIR1: First direction DIR2: Second direction DIR3: Third direction DIR4: Fourth direction DO: Offset amount E1: First end face E2: Second end face IS32: Inner principal surface KE: Back electromotive force constant

Claims

1. A rotating electrical machine comprising a rotor including a magnetized hard magnetic material and a magnetic core including teeth, wherein the teeth extend inwardly or outwardly in a direction opposite thereto toward the rotation axis of the rotor, and include a tooth main body portion around which a coil is wound, and a tooth tip portion formed at the tip of the tooth main body portion and facing the hard magnetic material, and having the tooth tip portion includes a first protruding portion protruding from the tooth main body portion in the axial direction along the rotation axis, the position of the magnetic center of the hard magnetic material and the magnetic center of the magnetic core are displaced in the axial direction along the rotation axis, and the protruding amount of the first protruding portion from the tooth main body portion is smaller than three times the gap width when the hard magnetic material and the tooth tip portion face each other, a rotating electrical machine.

2. the tooth tip portion includes a second protruding portion protruding from the tooth main body portion in a direction opposite to the first protruding portion in the axial direction along the rotation axis, and the protruding amount of the second protruding portion from the tooth main body portion is smaller than three times the gap width, the rotating electrical machine according to Claim 1.

3. the magnetic core is a molded body formed from soft magnetic powder, the rotating electrical machine according to Claim 1 or Claim 2.

4. The entire magnetic core including the first protruding portion is an integrally molded body, the rotating electrical machine according to Claim 1 or Claim 2.