Rotor, motor, and electronic apparatus

Abstract

This rotor (2) comprises: a magnetic body (10) having two magnetic pole parts (20), an annular part (30), and protruding parts (50) protruding from the annular part (30); and magnets (60) disposed between the two magnetic pole parts (20) in the circumferential direction. The magnetic body (10) comprises a plurality of magnetic members (100, 200) that are stacked in the axial direction. In the radial direction, the magnets (60) are in contact with the protruding parts (50). In the rotational axis direction, portions (150, 250) of the plurality of magnetic members (100, 200) constituting the protruding parts (50) are engaged with each other directly or via another member.

Description

Rotors, motors and electronic devices

[0001] The present invention relates to a rotor, a motor, and an electronic device.

[0002] Inner rotor motors include so-called Interior Permanent Magnet (IPM) rotors, in which plate-shaped magnets magnetized on both sides of the rotor are arranged in a radial spoke pattern so that two adjacent plate-shaped magnets repel each other.

[0003] JP 2013-529054 A JP 2021-158795 A

[0004] When an IPM rotor is used in a high ambient temperature, it is prone to demagnetization due to high heat on the outer diameter side. Furthermore, increasing the contact area between the magnet and the magnetic material can increase leakage flux to the inner diameter side. Such leakage flux and demagnetization hinder the improvement of motor characteristics.

[0005] In one aspect, an object is to provide a rotor, a motor, and an electronic device that can improve motor characteristics.

[0006] In one aspect, the rotor includes a magnetic body having two magnetic pole portions, an annular portion, and a protrusion protruding from the annular portion, and a magnet located between the two magnetic pole portions in the circumferential direction. The magnetic body includes a plurality of magnetic members stacked in the axial direction. The magnet contacts the protrusion in the radial direction. In the rotation axis direction, portions of the plurality of magnetic members constituting the protrusion engage with each other directly or via other members.

[0007] According to one aspect, the motor characteristics can be improved.

[0008] FIG. 1 is a perspective view showing an example of an electronic device according to an embodiment. FIG. 2 is an exploded perspective view showing an example of a motor according to an embodiment. FIG. 3 is a perspective view showing an example of a rotor core according to an embodiment. FIG. 4 is a cross-sectional view showing an example of a rotor into which a shaft is inserted according to an embodiment. FIG. 5 is an enlarged cross-sectional view showing an example of a rotor according to an embodiment. FIG. 6 is a cross-sectional perspective view showing an example of a rotor into which a shaft is inserted according to an embodiment. FIG. 7 is an enlarged cross-sectional view showing an example of a magnetic member according to an embodiment. FIG. 8 is a cross-sectional view showing an example of engaged magnetic members according to an embodiment. FIG. 9 is a diagram illustrating an example of insertion of an engaging member into a rotor according to a modified example. FIG. 10 is an enlarged cross-sectional view showing an example of a magnetic member according to another modified example.

[0009] Embodiments of a rotor, a motor, and an electronic device disclosed herein will be described in detail below with reference to the drawings. Note that the dimensional relationships and ratios of elements in the drawings may differ from reality. The drawings may also include portions where the dimensional relationships and ratios differ. To facilitate understanding, each drawing may illustrate a coordinate system that includes at least one of the axial direction (the rotational axis direction of the motor 1), radial direction, and circumferential direction of the motor 1, which will be described later. In the following description, the rotational axis direction of the motor 1 may be simply referred to as the "axial direction."

[0010] [First Embodiment] A motor 1 according to an embodiment is housed in, for example, an electronic device 900 as shown in Fig. 1. Fig. 1 is a perspective view showing an example of an electronic device according to an embodiment. Fig. 2 is an exploded perspective view showing an example of a motor according to an embodiment. As shown in Figs. 1 and 2, the motor 1 according to an embodiment includes a rotor 2, a shaft 90, and a stator 80. Note that the motor 1 described in the embodiment is, for example, an inner rotor brushless motor in which the stator 80 is located on the outer periphery of the rotor 2 in the radial direction.

[0011] The electronic device 900 is a device or a mobile object whose interior experiences a high ambient temperature, such as a hybrid vehicle. As shown in Fig. 1 , the electronic device 900 in this embodiment includes a motor 1 and a housing 940 that houses the motor 1.

[0012] The electronic device 900 may also include a motor 1 and one or more gears 910 and 920. The gear 910 is, for example, a worm gear, and rotates in conjunction with the shaft 90 of the motor 1. The gear 920 is, for example, a helical gear that meshes with the worm gear 910, and rotates in conjunction with the output shaft 930. With this configuration, the driving force of the shaft 90 of the motor 1 is transmitted to the output shaft 930 of the output gear 920.

[0013] As shown in Fig. 2, the stator 80 includes a yoke 81, teeth 82, coils 83, and insulators 84. The yoke 81 is an annular member formed on the outer periphery of the stator 80. The teeth 82 protrude radially inward from the yoke 81. The yoke 81 and the teeth 82 are formed by punching flat plate-like members made of a magnetic material such as a magnetic steel plate into the shape shown in Fig. 2 and stacking a plurality of such members in the axial direction. The coils 83 are wound around the teeth 82, for example, via insulators 84.

[0014] 1 and 2, the rotor 2 is rotatably inserted into the radially inner side of the stator 80. The rotor 2 includes a magnetic body 10 and a plurality of magnets 60.

[0015] As shown in Fig. 3, the magnetic body 10 has two magnetic pole portions 20, an annular portion 30, and a first protruding portion 50 protruding from the annular portion 30. Fig. 3 is a perspective view showing an example of a rotor core in an embodiment. The first protruding portion 50 is an example of a protruding portion.

[0016] The annular portion 30 is disposed on the inside in the radial direction of the magnetic body 10. This annular portion 30 forms the inner circumferential portion of the magnetic body 10. The magnetic pole portion 20 is disposed on the outside in the radial direction of the magnetic body 10. This magnetic pole portion 20 forms the outer circumferential portion of the magnetic body 10. The magnetic body 10 in the embodiment includes two or three or more magnetic pole portions 20. The multiple magnetic pole portions 20 are formed lined up in the circumferential direction.

[0017] Each magnetic pole portion 20 has an end portion (hereinafter referred to as a tip portion) 23 that protrudes radially inward, and an outer peripheral surface 22 that extends circumferentially. This tip portion 23 forms a part of the inner surface of the magnetic pole portion 20, and as shown in Figure 3, a recess 24 is formed between the two tip portions 23, forming another part of the inner surface of the magnetic pole portion 20. The outer peripheral surface 22 of this magnetic pole portion 20 forms the outer periphery of the magnetic body 10. Furthermore, an end portion 26 in the circumferential direction of the outer peripheral surface 21 of the magnetic pole portion 20 has a shape that is continuous in the circumferential or radial direction, and forms a curved surface.

[0018] The magnetic body 10 also includes a connecting portion 40 that connects the magnetic pole portion 20 and the annular portion 30. As shown in Fig. 3, the connecting portion 40 is formed between the magnetic pole portion 20 and the annular portion 30 in the radial direction. The connecting portion 40 is formed between the recesses 24 shown in Fig. 3 in the circumferential direction.

[0019] The magnet 60 in the embodiment is, for example, a plate-shaped magnet extending in the axial direction. As shown in FIG. 4, the magnet 60 is located between two magnetic pole portions 20 in the circumferential direction. FIG. 4 is a cross-sectional view showing an example of a rotor in the embodiment with a shaft inserted therethrough. FIG. 4 shows a cross-section of the rotor 2 in the embodiment with the shaft 90 inserted therethrough, taken along line A-A, as shown in FIG. 4. As shown in FIG. 4, the rotor 2 in the embodiment is a spoke-type IPM rotor, with multiple magnets 60 arranged radially. The outer diameter D0 of the rotor 2 in the embodiment shown in FIG. 4 is, for example, 24.5 mm.

[0020] As shown in Fig. 5, the magnet 60 has an inner end face (inner face) 61 in the radial direction, an outer end face (outer face) 62 in the radial direction, and side faces 63 and 64 in the circumferential direction. Fig. 5 is an enlarged cross-sectional view showing an example of a rotor in an embodiment. Fig. 5 is an enlarged view of a portion indicated by a frame F1 in Fig. 4. In the embodiment, the width W1 in the circumferential direction of the magnet 60 shown in Fig. 4 is, for example, the outer diameter D0 x 2.22 / 24.5, and the magnet length (length in the radial direction) W1 of the magnet 60 shown in Fig. 5 is, for example, the outer diameter D0 x 3.5 / 24.5.

[0021] In this embodiment, two magnets 60 adjacent to each other in the circumferential direction via a magnetic pole portion 20 are arranged so that the same poles face each other. For example, as shown in Figure 5, two magnets 60 adjacent to each other in the circumferential direction are arranged so that the N poles face each other.

[0022] In the rotor 2 shown in Figure 4, the magnets 60 arranged on the magnetic body 10 may move radially outside the magnetic body 10 or in the positive or negative axial direction due to the repulsive force with other adjacent magnets 60 in the circumferential direction or the centrifugal force generated by the rotation of the rotor 2.

[0023] Therefore, the rotor 2 in this embodiment further includes covers 170 and 180 as shown in Fig. 2. As shown in Fig. 2, the cover 170 is attached to the magnetic body 10 from the positive side in the axial direction, and the cover 180 is attached to the magnetic body 10 from the negative side in the axial direction.

[0024] As shown in FIG. 6, the cover 170 includes a plurality of outer peripheral portions 176, flat portions 175 extending in the radial direction, and an inner peripheral portion 173. FIG. 6 is a cross-sectional perspective view showing an example of a rotor into which a shaft is inserted in an embodiment. FIG. 6 shows a cross section taken along line B-B in FIG. 4. Note that the covers 170 and 180 in the embodiment have the same shape, and the matters described below for the cover 170 also apply to the cover 180 unless otherwise specified. Similarly, the matters described for the cover 180 also apply to the cover 170 unless otherwise specified.

[0025] In this embodiment, the cover 170 is made of a non-magnetic material such as brass. Alternatively, the cover 170 may be made by bending a material that has lower magnetic properties than the magnetic steel plate that constitutes the magnetic body 10, such as austenitic stainless steel.

[0026] As shown in Fig. 6 , each outer circumferential portion 176 protrudes from the flat portion 175 in the negative axial direction, and each outer circumferential portion 186 protrudes from the flat portion 185 in the positive axial direction. The multiple outer circumferential portions 176 and 186 are formed, for example, at equal intervals in the circumferential direction. More specifically, as shown in Figs. 4 and 6 , the outer circumferential portions 186 are formed at positions that contact the outer end faces 62 of the magnets 60 in the radial direction, and the multiple outer circumferential portions 186 are formed in the same number as the number of magnets 60.

[0027] Like the outer circumferential portion 176, the inner circumferential portion 173 protrudes from the flat portion 175 in the negative axial direction, and the inner circumferential portion 183 protrudes from the flat portion 185 in the positive axial direction. The outer diameters (size) of the inner circumferential portions 173 and 183 are, for example, approximately the same as or slightly larger than the inner diameter (size) of the second protrusion 31 formed on the annular portion 30 of the magnetic body 10. The inner diameters of the inner circumferential portions 173 and 183 are, for example, approximately the same as or slightly smaller than the outer diameter (size) of the shaft 90.

[0028] In this configuration, the covers 170 and 180 are inserted and press-fitted into the second protrusions 31 of the magnetic body 10 in the radial direction, for example. Then, the shaft 90 is inserted and press-fitted into the inner circumferential portions 173 and 183. That is, in this embodiment, the covers 170 and 180, the magnetic body 10, and the shaft 90 form a double press-fit structure. In this case, in the cross-sectional view shown in FIG. 4, the outer circumferential portion 186 and the inner circumferential portion 183 of the cover 180 are visible on the negative axial side. With this configuration, the contact area A1 between the covers 170 and 180 and the second protrusions 31 of the magnetic body 10 shown in FIG. 4 is reduced, thereby mitigating the stress applied to the magnetic body 10 from the covers 170 and 180.

[0029] Furthermore, the flat surface 175 of the cover 170 faces (or contacts) the magnet 60 from the positive axial direction, and the flat surface 185 of the cover 180 faces (or contacts) the magnet 60 from the negative axial direction. Furthermore, of the radially outer end face 62 of the magnet 60, a portion on the positive axial direction side faces (or contacts) the outer circumferential portion 176 of the cover 170 in the radial direction, and another portion on the negative direction side faces (or contacts) the outer circumferential portion 186 of the cover 180 in the radial direction. With this configuration, movement of the magnet 60 in the axial or radial direction is suppressed.

[0030] When the outer diameter D0 is small, as in the rotor 2 of the embodiment, it is difficult to form a structure in the covers 170 and 180 that holds the magnet 60 from the inside in the radial direction. For example, as shown in Figure 6, the inner end face 61 of the magnet 60 is located outside the inner circumferential portion 173 of the cover 170 and the inner circumferential portion 183 of the cover 180, and is located away from the inner circumferential portion 173 of the cover 170 and the inner circumferential portion 183 of the cover 180. Therefore, in the rotor 2 of the embodiment, the first protrusion 50 supports the inner surface 61 of the magnet 60 from the inside in the radial direction.

[0031] 5, the first protrusion 50 of the magnetic body 10 protrudes radially outward (toward the magnet 60) from the annular portion 30. At this time, the magnet 60 is in contact with the protrusion 50 in the radial direction. Specifically, a portion (contact portion 56) of the inner end surface 61 of the magnet 60 is in contact with the first protrusion 50 in the radial direction.

[0032] As shown in FIG. 7 , in the embodiment, the magnetic body 10 includes a plurality of magnetic members 100 and 200 stacked in the axial direction. FIG. 7 is an enlarged cross-sectional view showing an example of a magnetic member in the embodiment. As shown in FIG. 7 , the magnetic member 100 is stacked on another magnetic member 200 having the same shape as the magnetic member 100, from the positive side in the axial direction. Note that although FIG. 7 illustrates two magnetic members 100 and 200, the number of magnetic members stacked is not limited to this. Furthermore, in the following, the description of the magnetic member 100 also applies to the magnetic member 200 and other magnetic members.

[0033] 7, magnetic member 100 includes a first portion (hereinafter referred to as a magnetic pole portion constituent portion) 120 that constitutes the magnetic pole portion, a protruding portion 150, a second portion (hereinafter referred to as a connection portion constituent portion) 140 that constitutes the connection portion, and a third portion (hereinafter referred to as an annular portion constituent portion) 130 that constitutes the annular portion. Note that protruding portion 150 is an example of a portion of the multiple magnetic members that constitute the protruding portion.

[0034] In the embodiment, the magnetic pole portion constituent portion 120 of the magnetic member 100 engages with the magnetic pole portion constituent portion 220 of another magnetic member 200. For example, second engagement portions 127 and 227 are formed on portions of the magnetic members 100 and 200 constituting the magnetic pole portion 20. In this case, the magnetic pole portion constituent portions 120 and 220 are engaged with each other by crimping the second engagement portion 127 formed on the magnetic pole portion constituent portion 120 to the second engagement portion 227 formed on the magnetic pole portion constituent portion 220. That is, portions of the multiple magnetic members constituting the magnetic pole portion include the second engagement portions 127 and 227. For example, the second engagement portions 127 and 227 are located on the connecting portion 40 side in the radial direction. Furthermore, as described later, the magnetic pole portion constituent portions 120 and 220 may be engaged with each other by other members. That is, portions of the multiple magnetic members constituting the magnetic pole portion are engaged with the connecting portion side portions of the magnetic pole portions in the rotational axis direction, directly or via other members.

[0035] As shown in Fig. 8, the second engaging portion 127 of the magnetic member 100 and the second engaging portion 227 of another magnetic member 200 are crimped together to form the second connecting portion 28 shown in Fig. 4 in the magnetic pole portion 20 of the magnetic body 10. Fig. 8 is a cross-sectional view showing an example of engaged magnetic members in the embodiment. Note that the second connecting portion 28 is an example of a plurality of second engaging portions stacked in the rotation axis direction.

[0036] Stress remains in the second connecting portion 28 when the second engaging portions 127 and 227 are crimped together. This causes the magnetic permeability of the second connecting portion 28 to be lower than that of the other portions of the magnetic pole portion 20. In this case, the second connecting portion 28 forms a flux barrier in the magnetic body 10.

[0037] In the embodiment, the protruding portion 150 of the magnetic member 100 engages with the protruding portion 250 of another magnetic member 200. For example, as shown in FIG. 7 , the protruding portions 150 and 250 engage with each other by crimping the first engaging portion 157 formed on the protruding portion 150 with the first engaging portion 257 formed on the protruding portion 250. That is, each of the portions of the multiple magnetic members constituting the protruding portion includes a first engaging portion. As will be described later, the protruding portions 150 and 250 may be engaged with each other by other members. That is, in the rotational axis direction, the protruding portions 150 and 250 engage with each other directly or via other members. The connecting portion forming portion 140 is connected to the first engaging portion 157 of the magnetic member. The connecting portion forming portion 140 is an example of a portion of the magnetic member constituting the connecting portion.

[0038] 7 is crimped to the first engaging portion 157 of the magnetic member 100 and the first engaging portion 257 of the other magnetic member 200, whereby the first connecting portion 58 shown in Fig. 5 is formed on the first protruding portion 50 of the magnetic body 10. The first connecting portion 58 is an example of a first engaging portion stacked in the rotation axis direction.

[0039] The first connecting portion 58 has a lower magnetic permeability than the other portions of the first protruding portion 50 due to the stress remaining in the first connecting portion 58 when the first engaging portions 157 and 257 are crimped together. In this case, the first connecting portion 58 forms a flux barrier in the magnetic body 10.

[0040] 5, with this configuration, the magnetic paths M51 and M52 extending from the first protrusion 50 toward the annular portion 30 are narrowed by the first connecting portion 58. This makes it easier for magnetic saturation to occur in the magnetic paths M51 and M52, thereby preventing magnetic flux from leaking radially inward from the inner end face 61 of the magnet 60 via the magnetic paths M51 or M52.

[0041] Furthermore, as shown by the arrows in Figure 5, magnetic flux flows from the side surfaces 63 and 64 in the circumferential direction of the magnet 60 toward the outer peripheral surface 22 of the magnetic pole portion 20 via the tip portion 23 of the magnetic pole portion 20. At this time, since the end portion 26 of the outer peripheral surface 21 of the magnetic pole portion 20 has a shape (or a wide area) that widens toward the adjacent magnet 60 via the magnetic pole portion 20, a wide magnetic path M26 is formed in the magnetic pole portion 20. Furthermore, since the recessed portion 24 formed in the magnetic pole portion 20 acts as a flux barrier, leakage of magnetic flux to the inside in the radial direction is suppressed, and the magnetic flux flowing from the magnet 60 toward the stator 80 can be increased. Furthermore, when Id = 0 is controlled, the gap (air gap) between the rotor and the magnetic pole portion of the stator is narrowed when Id = 0 and the current amplitude is maximum, and the rotor is more strongly attracted to the stator, thereby improving torque.

[0042] Furthermore, in the radial direction, the outer end face 62 of the magnet 60 is located inside the magnetic body 10 from the outer peripheral surface 22 of the magnetic pole portion 20, so a space U is formed between two adjacent magnetic pole portions 20 in the circumferential direction. The outer peripheral portion 176 or 186 of the cover 170 or 180 is disposed in this space U. This space U becomes a gap G1 formed between two adjacent magnetic pole portions 20 in the circumferential direction. That is, the portion of the outer end face 62 of the magnet 60 exposed from the cover 170 or 180 is exposed to the stator 80 in the radial direction and directly faces the stator 80 shown in FIG. 2 without the magnetic body 10 in between. In this configuration, the gap G1 and the outer peripheral portions 176 and 186 act as flux barriers, so that magnetic flux from the outside of the magnet 60 in the radial direction also flows toward the magnetic path M26 of the magnetic pole portion 20 of the magnetic body 10, as shown by the arrows in FIG. 5 .

[0043] Furthermore, magnetic paths M21 and M22 from the magnet 60 toward the connecting portion 40 via the magnetic pole portion 20 are also narrowed by the second connecting portion 28 and the recess 24, making magnetic saturation more likely to occur. This further suppresses leakage of magnetic flux from the magnet 60, via the magnetic pole portion 20 and the connecting portion 40, to the annular portion 30 located radially inward.

[0044] 5 , in the embodiment, the connection portion 40 includes a plurality of branched branches (hereinafter referred to as branch portions 41 and 42). The connection portion 40 is connected to the annular portion 30 at its radially inner side via the branch portions 41 and 42. That is, the connection portion 40 includes the branch portions 41 and 42, which are a plurality of portions branched toward the annular portion 30. The branch portions 41 and 42 are connected to the annular portion 30.

[0045] In this case, a gap 43 is formed in a portion surrounded by the branched portions 41 and 42 of the connecting portion 40 and the annular portion 30. The gap 43 is disposed radially outside the second protruding portion 31, and the annular portion 30 and the gap 43 are adjacent to each other in the radial direction. That is, a gap is formed between the branched portions 41 and 42 in the circumferential direction.

[0046] The gap 43 also serves as a flux barrier, narrowing the magnetic paths M41 and M42 that pass through the branch portions 41 and 42 from the connection portion 40 toward the annular portion 30. This configuration also suppresses leakage of magnetic flux to the annular portion 30 located radially inward.

[0047] In the embodiment, the second protruding portion 31 and the magnetic pole portion 20 face each other in the radial direction via the gap 43 and the connection portion 40. In this case, the stress applied to the second protruding portion 31 in the radial direction when the shaft 90 is press-fitted is alleviated by the presence of the gap 43. In other words, when stress is transmitted to the outer circumferential surface 22 of the magnetic pole portion 20, deformation of the magnetic body 10 and deterioration of roundness are suppressed.

[0048] The motor 1 in this embodiment is required to generate high torque at high ambient temperatures, for example, at ambient temperatures of 120° C. to 150° C. In this case, in addition to demagnetization due to heat, the torque is suppressed by a demagnetizing field caused by the ampere turns of the coil 83.

[0049] It is known that magnets with a high dysprosium (Dy) content can be used to suppress demagnetization, but increasing the proportion of dysprosium in the magnet increases manufacturing costs and reduces residual magnetic flux density (Br).

[0050] Therefore, in this embodiment, as shown in FIG. 4, the magnet 60 is disposed radially inside the rotor 2. For example, the outer diameter D1 of the outer end face 62 of the magnet 60 is 22.6 mm. With this configuration, by ensuring a sufficient distance between the coil 83 of the stator 80, which is positioned radially outward, and the outer end face 62 of the magnet 60, the demagnetization rate of the magnet 60 due to heat and ampere turns can be kept low, for example, to a maximum of approximately 2%. This allows for high stall torque. Furthermore, a magnet with a low dysprosium content, such as one with Hcj = 1500 to 1600 KA / m, can be used for the magnet 60.

[0051] Furthermore, in a spoke-type IPM, if the magnets 60 are magnetized first, a reaction force will occur, making assembly difficult, so it is preferable to magnetize the magnets 60 after they are inserted into the magnetic body 10 (attached after magnetization).

[0052] On the other hand, magnetization may become impossible if the outer end face 62 of the magnet 60 becomes too close to the annular portion 30 in the radial direction. Also, if the radial length of the magnet 60 becomes too large, it may become difficult to apply a magnetic field to the entire magnet 60 during magnetization, so it is necessary to shorten the radial length of the magnet 60.

[0053] Therefore, in this embodiment, the radial length L1 of the magnet 60 (hereinafter referred to as the magnet length) shown in Figure 7 is shortened. For example, by setting the magnet length L1 to the outer diameter D of the rotor 2 × 3.5 / 24.5, the magnetization rate can be made 90% or higher.

[0054] Furthermore, in a motor equipped with an IPM rotor, it is known that, ignoring the leakage flux coefficient, increasing the surface area of ​​the magnet in contact with the magnetic pole portion 20 increases the torque constant. However, if the magnet 60 is extended radially close to the annular portion 30, the leakage coefficient increases, posing a problem that the magnet 60 and torque characteristics are no longer proportional. In particular, when the magnetic body 10 is formed with the first protrusion 50 that supports the inner end face 62 of the magnet 60 from the inside in the radial direction, as in the embodiment, magnetic flux is likely to leak into the annular portion 30 via the contact portion 56 between the magnet 60 and the first protrusion 50.

[0055] In this embodiment, by shortening the radial length (magnet length) L1 of the magnet 60, the magnet 60 is arranged so as not to be too close in the radial direction to the annular portion 30. For example, the inner diameter D2 of the inner end face 61 of the magnet 60 is equal to or greater than ½ of the outer diameter D0 of the rotor 2, and preferably equal to or greater than ⅔.

[0056] Furthermore, the motor 1 in the embodiment is a small-diameter motor, for example, with a rotor 2 having a diameter of 24.5 mm or less. When the outer diameter (size) of the rotor 2 is small, it may be difficult to manufacture the recess 24 with a fine shape. For example, it may be difficult to make the inner diameter R of the recess 24 0.25 mm or less.

[0057] In the magnetic body 10 of the embodiment, by forming the recess 24, it is possible to ensure a predetermined size of contact area between the magnetic pole portion 20 and the magnet 60 without extending the magnet 60 radially up to the annular portion 30. Furthermore, by enlarging the recess 24, it is possible to reduce the weight of the magnetic pole portion 20, thereby reducing the inertia of the rotating body.

[0058] As described above, the rotor 2 in this embodiment includes a magnetic body having two magnetic pole portions 20, an annular portion 30, and a protruding portion 50 protruding from the annular portion 30, and a magnet 60 located between the two magnetic pole portions 20 in the circumferential direction. The magnetic body 10 includes multiple magnetic members 100, 200 stacked in the axial direction. The magnet 60 contacts the protruding portion 50 in the radial direction. In the rotation axis direction, portions 150, 250 of the multiple magnetic members constituting the protruding portion 50 engage with each other directly or via other members. This configuration can suppress leakage of magnetic flux radially inward via the protruding portion 50, thereby improving motor characteristics.

[0059] Furthermore, with this configuration, the plurality of magnetic members 100 and 200 can be formed in the same shape, thereby improving the manufacturability of the rotor 2.

[0060] [Modifications] While the configuration of the embodiment has been described above, the embodiment is not limited to this. For example, the rotor 2 may be configured such that only one of the portions of the magnetic members constituting the protrusions and the portions of the magnetic pole portions on the connection side are engaged with each other as shown in Figure 5. In the following modifications, the same parts as those shown in the previously described drawings are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0061] Furthermore, the radial position of the outer end face 62 of the magnet 60 may be changed depending on, for example, the outer diameter of the rotor 2 and the thickness of the covers 170 and 180 .

[0062] Furthermore, the magnetic members 100 and 200 may be engaged with each other via other engaging members, such as screws 330 and 340 shown in Fig. 9. Fig. 9 is a diagram illustrating an example of inserting engaging members into a rotor in a modified example. The screws 330 and 340 are an example of other members.

[0063] The magnetic body 310 in this modified example is also formed by stacking a plurality of magnetic members. In the magnetic body 310 in this modified example, a through hole 329 is formed in the magnetic pole portion 20, and a screw 359 is formed in the connecting portion 40. A screw 330 is inserted into the through hole 329, and a screw 340 is inserted into the through hole 359. The screws 330 and 340 shown in FIG. 9 are formed from a material with a lower magnetic permeability than an electromagnetic steel sheet, such as stainless steel, for example. In other words, the plurality of magnetic members in this modified example are engaged with each other via the screws 330 and 340, which are other members.

[0064] Alternatively, instead of using screws, as shown in FIG. 10 , among the stacked magnetic members, two overlapping magnetic members 500 and 600 may be formed. One magnetic member 500 may have an engaging portion 527 such as a dowel on its surface facing the other magnetic member 600, and the other magnetic member 600 may have an engaged portion 629 such as a recess on its surface facing the first magnetic member 500. FIG. 10 is an enlarged cross-sectional view showing an example of a magnetic member in another modified example. The other magnetic member 600 may have a through-hole or the like as an engaged portion instead of a recess. The engaging portion 527 and the engaged portion 629 engage with each other to engage the two overlapping magnetic members 500 and 600. As in the embodiment, the two magnetic members 500 and 600 may have the same shape. In this case, as shown in FIG. 10 , one magnetic member 500 has a recess 529 on its surface opposite the other magnetic member 600.

[0065] The screws 330 and 340 may be inserted from the negative axial direction. Also, the engaging member may be inserted into only one of the through holes 329 and 359.

[0066] The material of the covers 170 and 180 may be any non-magnetic or low-magnetic material and is not limited to that described in the embodiment. Furthermore, the method of fixing the covers 170 and 180 to the magnetic body 10 may be shrink fitting, cold fitting, or other methods.

[0067] While the present invention has been described above based on the embodiments and modifications, it goes without saying that the present invention is not limited to the embodiments and modifications, and various modifications are possible without departing from the spirit of the present invention. Such modifications without departing from the spirit of the present invention are also included in the technical scope of the present invention, and this will be clear to those skilled in the art from the description of the claims.

[0068] 1 Motor, 2 Rotor, 10, 310 Magnetic body, 20 Magnetic pole portion, 28 Second connecting portion, 329 Through hole, 30 Annular portion, 31 Second protruding portion, 40 Connection portion, 41, 42 Branch portion, 43 Air gap, 50 First protruding portion, 58 First connecting portion, 359 Through hole, 60 Magnet, 61 Inner end surface, 62 Outer end surface, 63, 64 Side surface, 80 Stator, 90 Shaft, 100, 200 Magnetic member, 127 Second engaging portion, 157 First engaging portion, 170, 180 Cover, 330, 340 Screw, 900 Electronic device, 910 Worm, 920 Output gear, 930 Output shaft, 940 Housing

Claims

1. a magnetic body having two magnetic pole portions, an annular portion, and a protrusion protruding from the annular portion; a magnet located between the two magnetic pole portions in the circumferential direction; Equipped with the magnetic body includes a plurality of magnetic members stacked in an axial direction; The magnet is in contact with the protrusion in the radial direction, In the rotation axis direction, portions of the plurality of magnetic members constituting the protrusion are engaged with each other directly or via other members. Rotor.

2. The rotor according to claim 1 , wherein each of the plurality of magnetic members constituting the protrusion includes a first engagement portion.

3. The rotor according to claim 2 , wherein the plurality of first engagement portions stacked in the rotation axis direction form a flux barrier in the magnetic body.

4. the magnetic body includes a connection portion that connects the magnetic pole portion and the annular portion, a portion of the magnetic member constituting the connecting portion is connected to the first engaging portion of the magnetic member; The rotor of claim 2 .

5. the connecting portion includes a plurality of portions branching toward the annular portion, the branched portions are connected to the annular portion; A gap is formed between the branched portions in the circumferential direction. The rotor according to claim 4 .

6. 5. The rotor according to claim 4, wherein a portion of the plurality of magnetic members constituting the magnetic pole portions is engaged with a portion of the magnetic pole portion on the connection portion side in the direction of the rotation axis, directly or via another member.

7. a portion of the magnetic member constituting the magnetic pole portion includes a second engaging portion, The rotor according to claim 6 , wherein the second engagement portion is located on the connecting portion side.

8. The rotor according to claim 7 , wherein the plurality of second engagement portions stacked in the rotation axis direction form a flux barrier in the magnetic body.

9. A rotor according to any one of claims 1 to 8; A shaft, a stator; A motor comprising:

10. An electronic device comprising: the motor according to claim 9; and a housing that houses the motor.

11. An electronic device comprising the motor according to claim 9 and one or more gears.