Rotating electric machines

Abstract

To provide a rotary electric machine capable of improving each magnetization rate of a first magnet and a second magnet.SOLUTION: A rotary electric machine comprises: a cylinder stator; and a rotor 12 arranged at an inner side or an outer side of the stator. The rotor 12 includes: a cylinder rotor core 21; a plurality of first magnets 22a; and a plurality of second magnets 22b. Each magnetization direction of each first magnet 22a and each second magnet 22b is crossed to a radial direction of the rotor core 21. The magnetization direction of each second magnet 22b is different from the magnetization direction of each first magnet 22a. Each of the first magnets 22a and the second magnets 22b is alternately arranged to a peripheral direction of the rotor core 21. The rotor core 21 includes a first concave part 241 and a second concave part 242 that are concaved to the radial direction of the rotor core 21 from a second surface 21b positioned at the side opposite to a first surface 21a opposite to the stator. The first concave part 241 is arranged to the radial direction of the rotor core 21 only with each first magnet 22a. The second concave part 242 is arranged in the radial direction of the rotor core 21 only with each second magnet 22b.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine. [Background technology]

[0002] Patent Document 1 discloses a motor including a cylindrical stator and a cylindrical rotor disposed inside the stator. The rotor has a cylindrical rotor core, a plurality of first magnets, and a plurality of second magnets. The magnetization direction of the first magnets intersects the radial direction of the rotor core. The magnetization direction of the second magnets intersects the radial direction of the rotor core and is different from the magnetization direction of the first magnets. The first magnets and second magnets are alternately arranged in the circumferential direction of the rotor core. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-217269 Summary of the Invention [Problem to be solved by the invention]

[0004] The first and second magnets are magnetized by a magnetizing device while arranged in the rotor core. When the first and second magnets are magnetized so that their magnetization directions intersect the radial direction of the rotor core, portions of the first and second magnets may be difficult to magnetize, depending on the dimensions of the magnets and the arrangement of the magnets relative to the rotor core. When portions of the first and second magnets are difficult to magnetize, the magnetization rate of the first and second magnets decreases. Therefore, there has been a demand for an improvement in the magnetization rate of the first and second magnets when the first and second magnets are magnetized so that their magnetization directions intersect the radial direction of the rotor core. [Means for solving the problem]

[0005] A rotating electric machine for solving the above problems comprises a cylindrical stator and a cylindrical rotor arranged inside or outside the stator, the rotor having a cylindrical rotor core, a plurality of first magnets, and a plurality of second magnets, the magnetization direction of the first magnets intersects the radial direction of the rotor core, the magnetization direction of the second magnets intersects the radial direction of the rotor core and is different from the magnetization direction of the first magnets, the first magnets and the second magnets are arranged alternately in the circumferential direction of the rotor core, and the rotor core has a first recess and a second recess recessed in the radial direction of the rotor core from a second surface located opposite to a first surface facing the stator, the first recess is aligned radially with only the first magnets, and the second recess is aligned radially with only the second magnets.

[0006] When magnetizing the first magnet and the second magnet, a first magnetizing device is arranged on the first surface side of the rotor core, and a second magnetizing device is arranged on the second surface side of the rotor core. The first magnetizing device and the second magnetizing device each have a plurality of magnetizing teeth aligned in the circumferential direction of the rotor core. The first magnet and the second magnetizing device are magnetized by magnetic flux emitted from the magnetizing teeth passing through the first magnet and the second magnet. More specifically, the magnetic flux emitted from the magnetizing teeth of the first magnetizing device passes through the first surface side portions of the first magnet and the second magnet and returns to the magnetizing teeth of the first magnetizing device adjacent in the circumferential direction of the rotor core. This magnetizes the first surface side portions of the first magnet and the second magnet. The second surface of the rotor core has a first recess and a second recess. The first recess is aligned only with the first magnet in the radial direction of the rotor core. The second recess is aligned only with the second magnet in the radial direction of the rotor core. Therefore, the magnetic resistance of the portion of the rotor core on the second surface side that is radially aligned with only the first magnet is increased by the first recess. This prevents magnetic flux from the magnetizing teeth of the second magnetizing device from passing through the portion of the rotor core on the second surface side that is radially aligned with only the first magnet and returning to the magnetizing teeth of the second magnetizing device that is circumferentially adjacent to the rotor core. Furthermore, the magnetic resistance of the portion of the rotor core on the second surface side that is radially aligned with only the second magnet is increased by the second recess. This prevents magnetic flux from the magnetizing teeth of the second magnetizing device from passing through the portion of the rotor core on the second surface side that is radially aligned with only the second magnet and returning to the magnetizing teeth of the second magnetizing device that is circumferentially adjacent to the rotor core. Therefore, the magnetic flux from the magnetizing teeth of the second magnetizing device passes through the portions of the first magnet and the second magnet on the second surface side. This makes it easier for the portions of the first magnet and the second magnet on the second surface side to be magnetized. As a result, the magnetization efficiency of the first magnet and the second magnet is improved.

[0007] In the above rotating electric machine, the first magnet and the second magnet may each be composed of a pair of magnet components that are aligned circumferentially around the rotor core and that move away from each other in the radial direction of the rotor core from the first surface to the second surface, and the widths of the first recess and the second recess may become smaller in the radial direction of the rotor core from the second surface to the first surface.

[0008] It is preferable that the width of the first recess at the bottom of the first recess is small. If the width of the first recess at the bottom of the first recess is large, the distance from the inner surface defining the first recess to the first magnet becomes short, making it easier for magnetic flux saturation to occur after magnetization. Similarly, it is preferable that the width of the second recess at the bottom of the second recess is small. If the width of the second recess at the bottom of the second recess is large, the distance from the inner surface defining the second recess to the second magnet becomes short, making it easier for magnetic flux saturation to occur after magnetization.

[0009] On the other hand, it is preferable that the width of the first recess on the second surface of the rotor core be larger. This is because a larger width of the first recess on the second surface of the rotor core increases the magnetic resistance of the portion of the rotor core on the second surface side that is radially aligned with only the first magnet. In this case, the magnetic flux emitted from the magnetizing teeth of the second magnetizing device is more likely to pass through the portion of the rotor core on the second surface side that is radially aligned with only the first magnet and return to the magnetizing teeth of the adjacent second magnetizing device. Similarly, it is preferable that the width of the second recess on the second surface of the rotor core is larger. This is because a larger width of the second recess on the second surface of the rotor core increases the magnetic resistance of the portion of the rotor core on the second surface side that is radially aligned with only the second magnet. In this case, the magnetic flux emitted from the magnetizing teeth of the second magnetizing device is more likely to pass through the portion of the rotor core on the second surface side that is radially aligned with only the second magnet and return to the magnetizing teeth of the adjacent second magnetizing device. Therefore, the portions of the first magnet and the second magnet on the second surface side are more easily magnetized.

[0010] From the above, by reducing the width of the first recess and the second recess in the radial direction of the rotor core from the second surface to the first surface, magnetic flux saturation after magnetization is less likely to occur, and the portions of the first magnet and the second magnet on the second surface side are more easily magnetized.

[0011] In the above rotating electric machine, the first magnet and the second magnet may each be formed by a pair of magnet components that are aligned in the circumferential direction of the rotor core and that move away from each other in the radial direction of the rotor core from the first surface to the second surface, and the bottoms of the first recess and the second recess may be located between one of the magnet components and the other of the magnet components in the circumferential direction of the rotor core.

[0012] Compared to when the bottom of the first recess is not located between a pair of magnet components constituting the first magnet in the circumferential direction of the rotor core, the magnetic flux emitted from the magnetizing yoke of the second magnetizing device is more prevented from passing through the portion of the rotor core on the second surface side that is radially aligned with only the first magnet and returning to the magnetizing yoke of the adjacent second magnetizing device. Similarly, compared to when the bottom of the second recess is not located between a pair of magnet components constituting the second magnet in the circumferential direction of the rotor core, the magnetic flux emitted from the magnetizing yoke of the second magnetizing device is more prevented from passing through the portion of the rotor core on the second surface side that is radially aligned with only the second magnet and returning to the magnetizing yoke of the adjacent second magnetizing device. Therefore, the portions of the first magnet and the second magnet on the second surface side are more easily magnetized. [Effects of the Invention]

[0013] According to the present invention, the magnetization rate of the first magnet and the second magnet can be improved. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a plan view showing a rotating electric machine according to a first embodiment. [Figure 2] FIG. 2 is a partial plan view showing a rotor in the first embodiment. [Figure 3]FIG. 2 is a partial cross-sectional view showing a rotor and a magnetization device according to the first embodiment. [Figure 4] FIG. 10 is a partial plan view showing a rotor in a second embodiment. [Figure 5] FIG. 10 is a partial cross-sectional view showing a rotor and a magnetizing device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] [First embodiment] A first embodiment of a rotating electrical machine will be described below with reference to FIGS. 1 to 3. FIG. <Configuration of rotating electric machine> 1, the rotating electric machine 10 includes a cylindrical stator 11 and a cylindrical rotor 12. In this embodiment, the rotor 12 is disposed inside the stator 11. Therefore, the rotating electric machine 10 of this embodiment is an inner rotor type rotating electric machine.

[0016] The rotor 12 includes a cylindrical rotor core 21, a plurality of first magnets 22a, and a plurality of second magnets 22b. Although not shown, the rotor core 21 is formed by laminating a plurality of disc-shaped electromagnetic steel plates made of a magnetic material. The first magnets 22a and the second magnets 22b are, for example, neodymium magnets.

[0017] The rotor core 21 has a first surface 21a and a second surface 21b. The first surface 21a is a surface facing the stator 11. The second surface 21b is a surface located on the opposite side of the rotor core 21 from the first surface 21a in the radial direction of the rotor core 21. In the case of an inner rotor type rotating electrical machine, the first surface 21a is an outer peripheral surface of the rotor core 21. The second surface 21b is an inner peripheral surface of the rotor core 21.

[0018] 2, the rotor core 21 has a plurality of magnet insertion holes 23. The plurality of magnet insertion holes 23 are aligned in the circumferential direction of the rotor core 21. In this embodiment, the magnet insertion holes 23 penetrate the rotor core 21 in the axial direction.

[0019] In the first embodiment, each magnet insertion hole 23 is defined by a pair of insertion hole constituent portions 230 aligned in the circumferential direction of the rotor core 21. The pair of insertion hole constituent portions 230 are formed so as to move away from each other in the radial direction of the rotor core 21 from the first surface 21a to the second surface 21b. In other words, the magnet insertion holes 23 are formed in a V shape. In the present embodiment, each insertion hole constituent portion 230 opens at the first surface 21a of the rotor core 21.

[0020] The first magnet 22a and the second magnet 22b are each inserted into the magnet insertion hole 23. The first magnets 22a and the second magnets 22b are alternately arranged in the circumferential direction of the rotor core 21. As shown by the arrows in FIG. 2, the magnetization direction of the first magnet 22a and the magnetization direction of the second magnet 22b each intersect with the radial direction of the rotor core 21. The first magnet 22a and the second magnet 22b are arranged so that the same magnetic poles face each other in the circumferential direction of the rotor core 21. In other words, the south pole of the first magnet 22a and the south pole of the second magnet 22b face each other in the circumferential direction of the rotor core 21. The north pole of the first magnet 22a and the north pole of the second magnet 22b face each other in the circumferential direction of the rotor core 21. Therefore, the magnetization direction of the first magnet 22a and the magnetization direction of the second magnet 22b are different. The magnetization direction of first magnet 22a is a first direction in the circumferential direction of rotor core 21. The magnetization direction of second magnet 22b is a second direction that is opposite to the first direction in the circumferential direction of rotor core 21.

[0021] In the first embodiment, the first magnet 22a and the second magnet 22b are each formed of a pair of magnet constituent bodies 220. One magnet constituent body 220 is inserted into one of the insertion hole constituent portions 230 that constitute the magnet insertion hole 23, and the other magnet constituent body 220 is inserted into the other insertion hole constituent portion 230 that constitutes the magnet insertion hole 23. Therefore, the pair of magnet constituent bodies 220 are lined up in the circumferential direction of the rotor core 21. Furthermore, the pair of magnet constituent bodies 220 are arranged so as to become more distant from each other in the radial direction of the rotor core 21 from the first surface 21a to the second surface 21b. In other words, the first magnet 22a and the second magnet 22b each form a V shape.

[0022] The pair of magnet constituent bodies 220 are arranged so that different magnetic poles face each other in the circumferential direction of the rotor core 21. In other words, the south pole of one magnet constituent body 220 and the north pole of the other magnet constituent body 220 face each other in the circumferential direction of the rotor core 21.

[0023] The rotor core 21 has a plurality of first recesses 241 and a plurality of second recesses 242. The first recesses 241 and the second recesses 242 are each portions recessed from the second surface 21b of the rotor core 21 in the radial direction of the rotor core 21. In this embodiment, the first recesses 241 and the second recesses 242 each penetrate the rotor core 21 in the axial direction. In other words, the first recesses 241 and the second recesses 242 are each provided continuously in the axial direction of the rotor core 21.

[0024] The first recesses 241 and the second recesses 242 are arranged at equal intervals in the circumferential direction of the rotor core 21. The first recesses 241 and the second recesses 242 are alternately arranged in the circumferential direction of the rotor core 21. The first recesses 241 are aligned only with the first magnets 22a in the radial direction of the rotor core 21. The first recesses 241 are not aligned with the second magnets 22b in the radial direction of the rotor core 21. The second recesses 242 are aligned only with the second magnets 22b in the radial direction of the rotor core 21. The second recesses 242 are not aligned with the first magnets 22a in the radial direction of the rotor core 21.

[0025] In this embodiment, the first recess 241 and the second recess 242 each have a triangular shape when viewed in the axial direction of the rotor core 21. The width W24 of each of the first recess 241 and the second recess 242 gradually decreases from the second surface 21b toward the first surface 21a in the radial direction of the rotor core 21. The bottoms 24a of each of the first recess 241 and the second recess 242 are located at the vertices of the triangle.

[0026] The depth of the first recess 241, i.e., the distance from the second surface 21b of the rotor core 21 to the bottom 24a of the first recess 241, is longer than the distance from the second surface 21b of the rotor core 21 to the first magnet 22a. Therefore, the bottom 24a of the first recess 241 is located between the pair of magnet constituent bodies 220 that constitute the first magnet 22a in the circumferential direction of the rotor core 21. In other words, the bottom 24a of the first recess 241 is located between one magnet constituent body 220 and the other magnet constituent body 220 that constitute the first magnet 22a in the circumferential direction of the rotor core 21.

[0027] The depth of second recess 242, i.e., the distance from second surface 21b of rotor core 21 to bottom 24a of second recess 242, is longer than the distance from second surface 21b of rotor core 21 to second magnet 22b. Therefore, bottom 24a of second recess 242 is located between a pair of magnet components 220 that constitute second magnet 22b in the circumferential direction of rotor core 21. In other words, bottom 24a of second recess 242 is located between one magnet component 220 and the other magnet component 220 that constitute second magnet 22b in the circumferential direction of rotor core 21.

[0028] A distance P between the first recessed portion 241 and the second recessed portion 242 that are adjacent to each other in the circumferential direction of the rotor core 21 on the second surface 21b of the rotor core 21 is larger than a width W55 of the second magnetized teeth 55b, which will be described later.

[0029] <Permanent magnet magnetizing device> As shown in Fig. 3, the permanent magnet magnetizing device 50 includes a first magnetizing device 51 and a second magnetizing device 52. Although Fig. 3 is a cross-sectional view, hatching is omitted.

[0030] The first magnetization device 51 includes a first magnetization core 53 and a first magnetization coil 54. The first magnetization core 53 includes a cylindrical first magnetization yoke 53a and a plurality of first magnetized teeth 53b. The number of first magnetized teeth 53b is equal to the total number of first magnets 22a and second magnets 22b. The first magnetized teeth 53b protrude from the inner circumferential surface of the first magnetization yoke 53a. The plurality of first magnetized teeth 53b are arranged at equal intervals in the circumferential direction of the first magnetization yoke 53a. A first slot S1 is formed between adjacent first magnetized teeth 53b in the circumferential direction of the first magnetization yoke 53a. The first magnetization coil 54 is wound around the first magnetized tooth 53b. A portion of the first magnetization coil 54 passes through the first slot S1.

[0031] The second magnetization device 52 includes a second magnetization core 55 and a second magnetization coil 56. The second magnetization core 55 includes a cylindrical second magnetization yoke 55a and a plurality of second magnetized teeth 55b. The number of the second magnetized teeth 55b is the same as the number of the first magnetized teeth 53b. The second magnetized teeth 55b protrude from the outer circumferential surface of the second magnetization yoke 55a. The plurality of second magnetized teeth 55b are arranged at equal intervals in the circumferential direction of the second magnetization yoke 55a. A second slot S2 is formed between adjacent second magnetized teeth 55b in the circumferential direction of the second magnetization yoke 55a. The second magnetization coil 56 is wound around the second magnetized teeth 55b. A portion of the second magnetization coil 56 passes through the second slot S2.

[0032] [Operation of this embodiment] The operation of this embodiment will be explained together with the method of magnetizing the first magnet 22a and the second magnet 22b.

[0033] 3, the permanent magnet magnetizing device 50 is disposed relative to the rotor 12 having the first magnet 22a and the second magnet 22b before magnetization. The first magnetizing device 51 is disposed on the first surface 21a side of the rotor core 21, i.e., on the outside of the rotor 12. The second magnetizing device 52 is disposed on the second surface 21b side of the rotor core 21, i.e., on the inside of the rotor 12. The axial direction of the first magnetizing yoke 53a and the axial direction of the second magnetizing yoke 55a each coincide with the axial direction of the rotor core 21.

[0034] The tip surfaces of the first magnetized teeth 53b and the second magnetized teeth 55b face each other with the rotor 12 interposed therebetween. Portions of the magnets 22a and 22b on the second surface 21b side are located between the tip surfaces of the first magnetized teeth 53b and the second magnetized teeth 55b. The first slots S1 and the second slots S2 are aligned in the radial direction of the rotor core 21 with the rotor 12 interposed therebetween. The portion of the first magnet 22a on the first surface 21a side and the first recessed portion 241, or the portion of the second magnet 22b on the first surface 21a side and the second recessed portion 242, are located between the first slots S1 and the second slots S2.

[0035] Electricity is applied to the first magnetizing coil 54 and the second magnetizing coil 56. The direction of the current flowing through the portion of the first magnetizing coil 54 that passes through the first slot S1 is set to alternate between a direction toward one side of the axial direction of the first magnetizing yoke 53a and a direction toward the other side of the axial direction of the first magnetizing yoke 53a for each first slot S1. Similarly, the direction of the current flowing through the portion of the second magnetizing coil 56 that passes through the second slot S2 is set to alternate between a direction toward one side of the axial direction of the second magnetizing yoke 55a and a direction toward the other side of the axial direction of the second magnetizing yoke 55a for each second slot S2. In the first embodiment, the direction of the current flowing through the portion of the first magnetizing coil 54 that passes through the first slot S1 is the same as the direction of the current flowing through the portion of the second magnetizing coil 56 that passes through the second slot S2 that is radially aligned with the first slot S1.

[0036] The magnetic flux emitted from the first magnetized tooth 53b passes through the portions of the magnets 22a, 22b on the first surface 21a side and returns to the adjacent first magnetized tooth 53b in the circumferential direction of the first magnetized yoke 53a, thereby magnetizing the portions of the first magnet 22a and the second magnet 22b on the first surface 21a side.

[0037] Here, we will describe a case where the rotor core 21 does not have the first recess 241 and the second recess 242. In this case, as indicated by the two-dot chain arrow in FIG. 3 , the magnetic flux emitted from the second magnetized tooth 55b passes through a portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the first magnet 22a, and returns to the second magnetized tooth 55b adjacent in the circumferential direction of the second magnetized yoke 55a. The magnetic flux emitted from the second magnetized tooth 55b passes through a portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the second magnet 22b, and returns to the second magnetized tooth 55b adjacent in the circumferential direction of the second magnetized yoke 55a. In other words, the magnetic flux emitted from the second magnetized tooth 55b returns to the adjacent second magnetized tooth 55b without passing through the magnets 22a and 22b. Therefore, the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side are difficult to magnetize.

[0038] In contrast, in this embodiment, the rotor core 21 has a first recess 241 and a second recess 242 recessed from the second surface 21b. The first recess 241 is aligned radially with only the first magnet 22a of the rotor core 21. The second recess 242 is aligned radially with only the second magnet 22b of the rotor core 21. Therefore, the first recess 241 increases the magnetic resistance of the portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the first magnet 22a. This prevents magnetic flux from the second magnetized tooth 55b from passing through the portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the first magnet 22a and returning to the adjacent second magnetized tooth 55b. Furthermore, the second recess 242 increases the magnetic resistance of the portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the second magnet 22b. Therefore, the magnetic flux emitted from the second magnetized tooth 55b is prevented from passing through the portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the second magnet 22b and returning to the adjacent second magnetized tooth 55b.

[0039] In the first embodiment, the magnetic flux emitted from the second magnetized tooth 55b passes through the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side and flows to the first magnetized tooth 53b facing the second magnetized tooth 55b. Therefore, the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side are more easily magnetized than when the rotor core 21 does not have the first recess 241 and the second recess 242.

[0040] [Effects of this embodiment] The effects of this embodiment will be described. (1-1) The rotor core 21 has a first recess 241 and a second recess 242 recessed radially from the second surface 21b. The first recess 241 is aligned radially with only the first magnet 22a. The second recess 242 is aligned radially with only the second magnet 22b. Therefore, the first recess 241 increases the magnetic resistance of the portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the first magnet 22a. As a result, when the first magnet 22a and the second magnet 22b are magnetized, the magnetic flux emitted from the second magnetized tooth 55b is prevented from passing through the portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the first magnet 22a and returning to the second magnetized tooth 55b that is adjacent to the second magnetized yoke 55a in the circumferential direction. Furthermore, the second recess 242 increases the magnetic resistance of the portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the second magnet 22b. This prevents magnetic flux from passing through the portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the second magnet 22b and returning to the second magnetized tooth 55b that is adjacent to the second magnetized yoke 55a in the circumferential direction when the first magnet 22a and the second magnet 22b are magnetized. Therefore, the magnetic flux from the second magnetized tooth 55b passes through the portion of the first magnet 22a and the second magnet 22b on the second surface 21b side. This makes it easier for the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side to be magnetized. As a result, the magnetization rate of the first magnet 22a and the second magnet 22b is improved.

[0041] (1-2) One possible method for improving the magnetization rate of the first magnet 22a and the second magnet 22b is to increase the current flowing through the first magnetizing coil 54. In this case, the magnetic flux emitted from the first magnetized teeth 53b is more likely to reach the portions of the magnets 22a and 22b on the second surface 21b side, making it easier to magnetize the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side. However, this method increases the cost of the magnetizing device 50 and the power consumption of the magnetizing device 50. Furthermore, there is a limit to the power that can be supplied to the first magnetizing coil 54. In contrast, in this embodiment, the rotor core 21 is provided with the first recess 241 and the second recess 242, so that the second magnetizing device 52 can efficiently magnetize the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side. Therefore, the first magnet 22a and the second magnet 22b can be magnetized with less energy.

[0042] (1-3) One possible method for improving the magnetization rate of the first magnet 22a and the second magnet 22b is to provide a hole or the like in a portion of the rotor core 21 on the first surface 21a side, located between the first magnet 22a and the second magnet 22b. In this case, the magnetic flux from the first magnetized teeth 53b can more easily reach the portions of the magnets 22a and 22b on the second surface 21b side, making it easier to magnetize the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side. However, if a hole is provided in the portion of the rotor core 21 on the first surface 21a side, it becomes more difficult for the magnetic flux of the stator 11 to pass through the rotor core 21 during operation of the rotating electric machine 10, resulting in a decrease in torque. In contrast, in this embodiment, the first recess 241 and the second recess 242 are provided on the second surface 21b of the rotor core 21, making it easier to magnetize the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side. This prevents the magnetic flux of stator 11 from becoming difficult to pass through rotor core 21 during operation of rotary electric machine 10. This prevents torque from decreasing.

[0043] (1-4) In this embodiment, the first magnet 22a and the second magnet 22b are each composed of a pair of magnet components 220 that are aligned in the circumferential direction of the rotor core 21 and that are spaced apart from each other in the radial direction of the rotor core 21 from the first surface 21a to the second surface 21b.

[0044] In this case, it is preferable that the width W24 of the first recess 241 at the bottom 24a of the first recess 241 is small. This is because if the width W24 of the first recess 241 at the bottom 24a of the first recess 241 is large, the distance between the inner surface defining the first recess 241 and the first magnet 22a becomes short, making it easier for magnetic flux saturation to occur after magnetization. Similarly, it is preferable that the width W24 of the second recess 242 at the bottom 24a of the second recess 242 is small. This is because if the width W24 of the second recess 242 at the bottom 24a of the second recess 242 is large, the distance between the inner surface defining the second recess 242 and the second magnet 22b becomes short, making it easier for magnetic flux saturation to occur after magnetization.

[0045] On the other hand, it is preferable that the width W24 of the first recess 241 on the second surface 21b of the rotor core 21 be large. This is because a larger width W24 of the first recess 241 on the second surface 21b of the rotor core 21 increases the magnetic resistance in the portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the first magnet 22a. In this case, the magnetic flux emitted from the second magnetized tooth 55b is more likely to pass through the portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the first magnet 22a and return to the adjacent second magnetized tooth 55b. Similarly, it is preferable that the width W24 of the second recess 242 on the second surface 21b of the rotor core 21 be large. This is because a larger width W24 of the second recess 242 on the second surface 21b of the rotor core 21 increases the magnetic resistance in the portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the second magnet 22b. In this case, the magnetic flux emitted from the second magnetized tooth 55b is more likely to be prevented from returning to the adjacent second magnetized tooth 55b through a portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the second magnet 22b. Therefore, the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side are more likely to be magnetized.

[0046] In this embodiment, the width W24 of the first recess 241 and the second recess 242 decreases from the second surface 21b toward the first surface 21a in the radial direction of the rotor core 21. This makes it less likely for magnetic flux saturation to occur after magnetization, and makes it easier for the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side to be magnetized.

[0047] (1-5) The bottom 24a of the first recess 241 is located between the pair of magnet components 220 that make up the first magnet 22a in the circumferential direction of the rotor core 21. Therefore, compared to when the bottom 24a of the first recess 241 is not located between the pair of magnet components 220 that make up the first magnet 22a in the circumferential direction of the rotor core 21, the magnetic flux emitted from the second magnetized tooth 55b is more prevented from passing through a portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the first magnet 22a and returning to the adjacent second magnetized tooth 55b. Similarly, the bottom 24a of the second recess 242 is located between the pair of magnet components 220 that make up the second magnet 22b in the circumferential direction of the rotor core 21. Therefore, compared to when the bottom 24a of the second recess 242 is not positioned between the pair of magnet components 220 that constitute the second magnet 22b in the circumferential direction of the rotor core 21, the magnetic flux emitted from the second magnetized tooth 55b is more likely to be prevented from passing through a portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the second magnet 22b and returning to the adjacent second magnetized tooth 55b. This makes it easier for the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side to be magnetized.

[0048] (1-6) The distance P between the first recess 241 and the second recess 242 on the second surface 21b of the rotor core 21 is larger than the width W55 of the second magnetized tooth 55b. Therefore, the entire tip surface of the second magnetized tooth 55b faces the second surface 21b of the rotor core 21. This makes it easier for magnetic flux emitted from the second magnetized tooth 55b to enter the rotor core 21.

[0049] [Second embodiment] A second embodiment of a rotating electrical machine will be described below with reference to Figures 4 and 5. Note that a description of the same configuration as in the first embodiment will be omitted.

[0050] 4, in this embodiment, the magnet insertion holes 23 are formed closer to the first surface 21a than the radial center of the rotor core 21. In this embodiment, the shape of the magnet insertion holes 23 when viewed from the axial direction of the rotor core 21 is rectangular.

[0051] 4, the magnetization directions of the first magnet 22a and the second magnet 22b intersect with the radial direction of the rotor core 21. In the second embodiment, the magnetization directions of the first magnet 22a and the second magnet 22b are substantially perpendicular to the radial direction of the rotor core 21. In this embodiment, the first magnet 22a and the second magnet 22b are inserted into the magnet insertion holes 23, and are thereby disposed closer to the first surface 21a than the center of the rotor core 21 in the radial direction. Therefore, the distance from the first surface 21a of the rotor core 21 to the magnets 22a, 22b in the radial direction of the rotor core 21 is shorter than the distance from the second surface 21b of the rotor core 21 to the magnets 22a, 22b in the radial direction of the rotor core 21.

[0052] In this embodiment, the first recess 241 and the second recess 242 each have a trapezoidal shape when viewed in the axial direction of the rotor core 21. A width W24 of each of the first recess 241 and the second recess 242 gradually increases in the radial direction of the rotor core 21 from the second surface 21b toward the first surface 21a.

[0053] The width W24a of the first recess 241 at the bottom 24a of the first recess 241 is approximately the same as the width W22 of the first magnet 22a. The width W24a of the second recess 242 at the bottom 24a of the second recess 242 is approximately the same as the width W22 of the second magnet 22b.

[0054] The distance P between the first recessed portion 241 and the second recessed portion 242 that are adjacent to each other in the circumferential direction of the rotor core 21 on the second surface 21b of the rotor core 21 is substantially the same as the width W55 of the second magnetized tooth 55b.

[0055] The distance L from the first magnet 22a to the first recess 241 in the radial direction of the rotor core 21 is set to be short within a range that ensures the strength of the rotor core 21. The distance L from the second magnet 22b to the second recess 242 in the radial direction of the rotor core 21 is set to be short within a range that ensures the strength of the rotor core 21.

[0056] [Operation of this embodiment] The operation of this embodiment will be explained together with the method of magnetizing the first magnet 22a and the second magnet 22b.

[0057] As shown in Figure 5, a permanent magnet magnetization device 50 is disposed relative to a rotor 12 having a first magnet 22a and a second magnet 22b before magnetization. The first magnetization device 51 is disposed on the first surface 21a side of the rotor core 21, i.e., on the outside of the rotor 12. The second magnetization device 52 is disposed on the second surface 21b side of the rotor core 21, i.e., on the inside of the rotor 12. The axial direction of the first magnetization yoke 53a and the axial direction of the second magnetization yoke 55a are aligned with the axial direction of the rotor core 21, respectively. Note that although Figure 5 is a cross-sectional view, hatching has been omitted.

[0058] The tip surface of the first magnetized tooth 53b and the tip surface of the second magnetized tooth 55b face each other via the rotor core 21. The first slot S1 and the second slot S2 are aligned in the radial direction of the rotor core 21 via the rotor 12. The first magnet 22a and the first recess 241, or the second magnet 22b and the second recess 242, are positioned between the first slot S1 and the second slot S2.

[0059] Electricity is applied to the first magnetizing coil 54 and the second magnetizing coil 56. In the second embodiment, the direction of the current flowing through the portion of the first magnetizing coil 54 that passes through the first slot S1 is opposite to the direction of the current flowing through the portion of the second magnetizing coil 56 that passes through the second slot S2 that is aligned radially with the first slot S1.

[0060] The magnetic flux emitted from the first magnetized tooth 53b passes through the portions of the magnets 22a, 22b on the first surface 21a side and returns to the adjacent first magnetized tooth 53b in the circumferential direction of the second magnetized yoke 55a, thereby magnetizing the portions of the first magnet 22a and the second magnet 22b on the first surface 21a side.

[0061] Here, we will describe a case where the rotor core 21 does not have the first recess 241 and the second recess 242. In this case, as indicated by the two-dot chain arrow in Fig. 5, the magnetic flux emitted from the second magnetized tooth 55b passes through a portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the first magnet 22a, and returns to the second magnetized tooth 55b adjacent in the circumferential direction of the second magnetized yoke 55a. The magnetic flux emitted from the second magnetized tooth 55b passes through a portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the second magnet 22b, and returns to the second magnetized tooth 55b adjacent in the circumferential direction of the second magnetized yoke 55a. In other words, the magnetic flux emitted from the second magnetized tooth 55b returns to the adjacent second magnetized tooth 55b without passing through the magnets 22a and 22b. Therefore, the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side are difficult to magnetize.

[0062] In contrast, in this embodiment, the rotor core 21 has a first recess 241 and a second recess 242 recessed from the second surface 21b. The first recess 241 is aligned radially with only the first magnet 22a of the rotor core 21. The second recess 242 is aligned radially with only the second magnet 22b of the rotor core 21. Therefore, the first recess 241 increases the magnetic resistance of the portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the first magnet 22a. This prevents magnetic flux from the second magnetized tooth 55b from passing through the portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the first magnet 22a and returning to the adjacent second magnetized tooth 55b. Furthermore, the second recess 242 increases the magnetic resistance of the portion of the rotor core 21 on the second surface 21b side that is aligned radially with only the second magnet 22b. Therefore, the magnetic flux emitted from the second magnetized tooth 55b is prevented from passing through the portion of the rotor core 21 on the second surface 21b side that is radially aligned with only the second magnet 22b and returning to the adjacent second magnetized tooth 55b.

[0063] In the second embodiment, the magnetic flux emitted from the second magnetized tooth 55b passes through the portions of the magnets 22a, 22b on the second surface 21b side and returns to the second magnetized tooth 55b adjacent in the circumferential direction of the second magnetized yoke 55a. Therefore, the portions of the first magnet 22a and the second magnet 22b on the second surface 21b side are more easily magnetized than when the rotor core 21 does not have the first recess 241 and the second recess 242.

[0064] [Effects of this embodiment] In the second embodiment, in addition to the effects (1-1) and (1-2) of the first embodiment, the following effects can be obtained.

[0065] (2-1) For example, if the magnets 22a, 22b are provided at the radial center of the rotor core 21, the distance from the first surface 21a to the magnets 22a, 22b in the radial direction of the rotor core 21 is the same as the distance from the second surface 21b to the magnets 22a, 22b in the radial direction of the rotor core 21. In this case, it is conceivable to provide the first recess 241 and the second recess 242 not only on the second surface 21b of the rotor core 21 but also on the first surface 21a so that the magnetic flux emitted from the first magnetized tooth 53b can easily pass through the portions of the magnets 22a, 22b on the first surface 21a side of the rotor core 21. However, if the first recess 241 and the second recess 242 are provided on the first surface 21a of the rotor core 21, it becomes difficult for the magnetic flux of the stator 11 to pass through the rotor core 21 during operation of the rotating electric machine 10, resulting in a decrease in torque.

[0066] In contrast, in this embodiment, the magnets 22a, 22b are disposed closer to the first surface 21a than the radial center of the rotor core 21. This shortens the radial distance from the first surface 21a to the magnets 22a, 22b of the rotor core 21. This makes it easier for the magnetic flux emitted from the first magnetized teeth 53b to pass through the portions of the magnets 22a, 22b on the first surface 21a side. This allows the portions of the first magnet 22a and the second magnet 22b on the first surface 21a side to be efficiently magnetized without reducing torque.

[0067] Note that the distance from second surface 21b to magnets 22a, 22b in the radial direction of rotor core 21 becomes longer by the amount that the distance from first surface 21a to magnets 22a, 22b in the radial direction of rotor core 21 becomes shorter. However, because first recess 241 and second recess 242 can be provided on second surface 21b of rotor core 21, the portions of first magnet 22a and second magnet 22b on the second surface 21b side can also be magnetized.

[0068] (2-2) For example, if the width W24a of the first recess 241 at the bottom 24a of the first recess 241 is larger than the width W22 of the first magnet 22a, the magnetic flux emitted from the second magnetized tooth 55b is prevented from passing through the first magnet 22a and returning to the adjacent second magnetized tooth 55b. On the other hand, if the width W24a of the first recess 241 at the bottom 24a of the first recess 241 is smaller than the width W22 of the first magnet 22a, the magnetic flux emitted from the N pole of the first magnet 22a is more likely to return to its own S pole. In this embodiment, the width W24 of the first recess 241 at the bottom 24a of the first recess 241 is approximately the same as the width W22 of the first magnet 22a. This prevents the first recess 241 from interfering with the flow of magnetic flux for magnetizing the first magnet 22a. Furthermore, since the magnetic flux emitted from the north pole of the first magnet 22a is less likely to return to its own south pole, part of the magnetic force of the first magnet 22a is less likely to become wasted magnetic force that does not contribute to the operation of the rotating electric machine 10.

[0069] Similarly, if the width W24a of the second recess 242 at the bottom 24a of the second recess 242 is larger than the width W22 of the second magnet 22b, the magnetic flux emitted from the second magnetized tooth 55b is prevented from passing through the second magnet 22b and returning to the adjacent second magnetized tooth 55b. On the other hand, if the width W24a of the second recess 242 at the bottom 24a of the second recess 242 is smaller than the width W22 of the second magnet 22b, the magnetic flux emitted from the N pole of the second magnet 22b is more likely to return to its S pole. In this embodiment, the width W24 of the second recess 242 at the bottom 24a of the second recess 242 is approximately the same as the width W22 of the second magnet 22b. This prevents the second recess 242 from interfering with the flow of magnetic flux for magnetizing the second magnet 22b. Furthermore, since the magnetic flux emitted from the north pole of the second magnet 22b is less likely to return to its own south pole, part of the magnetic force of the second magnet 22b is less likely to become wasted magnetic force that does not contribute to the operation of the rotating electric machine 10.

[0070] (2-3) In the present embodiment, the distance L from the first magnet 22a to the first recess 241 in the radial direction of the rotor core 21 is set to be short within a range that ensures the strength of the rotor core 21. The shorter the distance L, the more difficult it is for the magnetic flux emitted from the N pole of the first magnet 22a to return to its own S pole. Furthermore, the distance L from the second magnet 22b to the second recess 242 in the radial direction of the rotor core 21 is set to be short within a range that ensures the strength of the rotor core 21. The shorter the distance L, the more difficult it is for the magnetic flux emitted from the N pole of the second magnet 22b to return to its own S pole. Therefore, it is less likely that part of the magnetic force of the magnets 22a, 22b will become wasted magnetic force that does not contribute to the operation of the rotating electric machine 10.

[0071] (2-4) The distance P between the first recess 241 and the second recess 242 on the second surface 21b of the rotor core 21 is approximately the same as the width W55 of the second magnetized tooth 55b. Therefore, the entire tip surface of the second magnetized tooth 55b faces the second surface 21b of the rotor core 21. This makes it easier for magnetic flux emitted from the second magnetized tooth 55b to enter the rotor core 21.

[0072] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0073] The rotor 12 may be disposed outside the stator 11. That is, the rotating electric machine 10 may be an outer rotor type rotating electric machine. In this case, the inner peripheral surface of the rotor core 21 is the first surface 21a facing the stator 11. The outer peripheral surface of the rotor core 21 is the second surface 21b located opposite the first surface 21a. Therefore, the first recess 241 and the second recess 242 are provided on the outer peripheral surface of the rotor core 21.

[0074] In the first embodiment, the insertion hole forming portion 230 does not have to be open on the first surface 21 a of the rotor core 21 . In the first and second embodiments, the shapes of the recesses 241 and 242 may be changed as appropriate.

[0075] For example, the shape of the recesses 241, 242 may be rectangular when viewed in the axial direction of the rotor core 21. That is, the width W24 of the recesses 241, 242 may be constant in the radial direction of the rotor core 21.

[0076] For example, the width W24 of the recesses 241, 242 does not have to gradually change in the radial direction of the rotor core 21. The width W24 of the recesses 241, 242 may change in multiple steps in the radial direction of the rotor core 21.

[0077] For example, the recesses 241, 242 may have a semicircular shape when viewed in the axial direction of the rotor core 21. In other words, the inner surfaces defining the recesses 241, 242 may extend in an arc shape.

[0078] In the first embodiment, the depth of the first recess 241, i.e., the distance from the second surface 21b of the rotor core 21 to the bottom 24a of the first recess 241, may be shorter than the distance from the second surface 21b of the rotor core 21 to the first magnet 22a. In this case, the bottom 24a of the first recess 241 is not located between the pair of magnet components 220 that constitute the first magnet 22a in the circumferential direction of the rotor core 21.

[0079] Similarly, the depth of second recess 242, i.e., the distance from second surface 21b of rotor core 21 to bottom 24a of second recess 242, may be shorter than the distance from second surface 21b of rotor core 21 to second magnet 22b. In this case, bottom 24a of second recess 242 is not located between the pair of magnet components 220 that constitute second magnet 22b in the circumferential direction of rotor core 21.

[0080] In the first embodiment, the distance P between the first recess 241 and the second recess 242 on the second surface 21b of the rotor core 21 may be equal to or less than the width W55 of the second magnetized tooth 55b. In the second embodiment, the width W24a of the recesses 241, 242 at the bottoms 24a of the recesses 241, 242 may be greater than or less than the width W22 of the magnets 22a, 22b. Furthermore, the distance P between the first recess 241 and the second recess 242 on the second surface 21b of the rotor core 21 may be greater than or less than the width W55 of the second magnetized tooth 55b. Depending on the width W22 of the magnets 22a, 22b and the width W55 of the second magnetized tooth 55b, the shape of the recesses 241, 242 as viewed in the axial direction of the rotor core 21 may be a trapezoid in which the width W24 gradually decreases from the second surface 21b toward the first surface 21a in the radial direction of the rotor core 21.

[0081] When rotor core 21 is formed by stacking multiple electromagnetic steel sheets as in the first and second embodiments, recesses 241, 242 are formed by stacking multiple electromagnetic steel sheets each having a recess-forming portion recessed from the outer circumferential surface. In this case, all of the electromagnetic steel sheets forming rotor core 21 may have the recess-forming portion, or only some of the multiple electromagnetic steel sheets forming rotor core 21 may have the recess-forming portion.

[0082] When all of the electromagnetic steel sheets forming the rotor core 21 have recess-forming portions, as in the first and second embodiments, the recesses 241, 242 are provided continuously in the axial direction of the rotor core 21. On the other hand, when some of the electromagnetic steel sheets have recess-forming portions, the recesses 241, 242 may be provided discontinuously in the axial direction of the rotor core 21, for example, by alternately stacking electromagnetic steel sheets having recess-forming portions and electromagnetic steel sheets not having recess-forming portions. In this case, the strength of the rotor core 21 is increased compared to when all of the electromagnetic steel sheets have recess-forming portions. [Explanation of symbols]

[0083] 10...rotating electric machine, 11...stator, 12...rotor, 21...rotor core, 21a...first surface, 21b...second surface, 22a...first magnet, 22b...second magnet, 24a...bottom, 220...magnet component, 241...first recess, 242...second recess.

Claims

1. a cylindrical stator and a cylindrical rotor disposed inside or outside the stator; the rotor has a cylindrical rotor core, a plurality of first magnets, and a plurality of second magnets; the magnetization direction of the first magnet intersects with the radial direction of the rotor core, the magnetization direction of the second magnet intersects with the radial direction of the rotor core and is different from the magnetization direction of the first magnet, the first magnets and the second magnets are alternately arranged in a circumferential direction of the rotor core, the rotor core has a first recess and a second recess recessed in a radial direction of the rotor core from a second surface located on the opposite side to a first surface facing the stator, the first recess is aligned with only the first magnet in the radial direction of the rotor core, and the second recess is aligned with only the second magnet in the radial direction of the rotor core, the first magnet and the second magnet are each configured by a pair of magnet components that are aligned in the circumferential direction of the rotor core and that are spaced apart from each other in the radial direction of the rotor core from the first surface toward the second surface, bottoms of the first recess and the second recess are located between one of the magnet constituent bodies and the other of the magnet constituent bodies in the circumferential direction of the rotor core, a distance from the second surface of the rotor core to a bottom of the first recess is longer than a distance from the second surface of the rotor core to the first magnet; a distance from the second surface of the rotor core to a bottom of the second recess is longer than a distance from the second surface of the rotor core to the second magnet.

2. A rotating electric motor as described in Claim 1, wherein the widths of the first recess and the second recess become smaller in the radial direction of the rotor core from the second surface toward the first surface.

Images