Rotor and motor

Abstract

The present invention provides a rotor and a motor that can suppress cogging torque and heat generation when the motor operates. The rotor includes: a sleeve fixed to the radially outer side of a rotating shaft; a plurality of magnets disposed on the radially outer side of the sleeve; and a reinforcing member in a cylindrical shape, the reinforcing member surrounding the plurality of magnets in a manner of abutting against the outer surfaces of the plurality of magnets, and sandwiching the plurality of magnets between the reinforcing member and the sleeve. Each of the plurality of magnets has: a central portion in the circumferential direction that abuts against the sleeve; and an end portion in the circumferential direction that has a thickness smaller than that of the central portion, and a gap is formed between the end portion and the sleeve.

Description

Technical Field

[0001] The present invention relates to a rotor of an electric motor and an electric motor including the rotor. Background Art

[0002] There is known an electric motor in which a magnet is sandwiched between a sleeve and a reinforcing member (for example, Japanese Patent Application Laid-Open No. 2017-195751).

[0003] Conventionally, there has been a demand for a technique for suppressing cogging torque and heat generation during operation of an electric motor. Summary of the Invention

[0004] In one aspect of the present disclosure, a rotor of an electric motor includes: a sleeve fixed to the radially outer side of a rotating shaft; a plurality of magnets disposed on the radially outer side of the sleeve; and a reinforcing member having a cylindrical shape that surrounds the plurality of magnets in contact with the outer surfaces of the plurality of magnets, and sandwiches the plurality of magnets between the reinforcing member and the sleeve. Each of the plurality of magnets has: a central portion in the circumferential direction that contacts the sleeve; and an end portion in the circumferential direction having a thickness smaller than that of the central portion, and a gap is formed between the end portion and the sleeve.

[0005] According to the present disclosure, it is possible to simultaneously suppress cogging torque and heat generation during operation of the electric motor, apply the electric motor to high-speed rotation, simplify the manufacturing process of the rotor, and prevent the disappearance of the gap due to deformation of the magnet. Brief Description of the Drawings

[0006] Figure 1 is a cross-sectional view of an electric motor according to an embodiment taken along a plane parallel to the rotation axis of the rotor.

[0007] Figure 2 is a cross-sectional view taken along a plane orthogonal to the rotation axis Figure 1 of the rotor shown.

[0008] Figure 3 is Figure 2 an enlarged view of region III in

[0009] Figure 4 is a view of a rotor according to another embodiment, which is a cross-sectional view corresponding to Figure 3 the one shown.

[0010] Figure 5 is a view of a rotor according to still another embodiment, which is a cross-sectional view corresponding to Figure 3 the one shown.

[0011] Figure 6 is a view of a rotor according to still another embodiment, which is a cross-sectional view corresponding to Figure 3 the one shown.

[0012] Figure 7 is a cross-sectional view taken along line VII-VII in Figure 6 .

[0013] Figure 8 is a view of a rotor of another embodiment and is a cross-sectional view corresponding to Figure 2 .

[0014] Figure 9 is an enlarged view of region IX in Figure 8 .

[0015] Figure 10 is a view of a rotor of another embodiment and is a cross-sectional view corresponding to Figure 2 .

[0016] Figure 11 is a view of a rotor of another embodiment and is a cross-sectional view corresponding to Figure 4 .

[0017] Figure 12 is a view of a rotor of another embodiment and is a cross-sectional view corresponding to Figure 4 .

[0018] Figure 13 is a view of a rotor of another embodiment and is a cross-sectional view corresponding to Figure 3 . DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, in the various embodiments described below, the same reference numerals are assigned to the same elements, and redundant descriptions are omitted. Further, in the following description, the axial direction represents the direction along the rotation axis A of the rotor 12, the radial direction represents the radial direction of a circle centered on the rotation axis A, and the circumferential direction represents the circumferential direction of the circle. Further, for convenience, the direction indicated by the arrow B in Figure 1 is defined as the front in the axial direction, the direction indicated by the arrow C in Figure 2 is defined as one direction in the circumferential direction, and the direction opposite to the arrow C is defined as the other direction in the circumferential direction.

[0020] First, a description will be given of a motor 10 according to an embodiment with reference to Figure 1 . The motor 10 includes a rotor 12, a stator 14, and a housing 16. The rotor 12 is disposed radially inside the stator 14 so as to be rotatable about the rotation axis A. The stator 14 is fixed to the housing 16. A coil 18 is wound around the stator 14. The rotor 12 is subjected to a force from the rotating magnetic field generated by the voltage applied to the coil 18 and rotates about the axis A.

[0021] Next, a description will be given with reference to Figures 2 to 4, the rotor 12 will be described. The rotor 12 has a rotating shaft 20, a sleeve 22, a plurality of magnets 24, and a reinforcing member 26. The rotating shaft 20 is a hollow member having a cylindrical outer peripheral surface 20a and extending in the axial direction. The top end (not shown) of the rotating shaft 20 is connected to an external structure such as a drive shaft of a robot or a cutting tool of a machine tool, and outputs a rotational force to the external structure.

[0022] The sleeve 22 is fixed to the outer peripheral surface 20a of the rotating shaft 20. In the present embodiment, the sleeve 22 is cylindrical and has an outer peripheral surface 22a and an inner peripheral surface 22b on the side opposite to the outer peripheral surface 22a. The outer peripheral surface 22a and the inner peripheral surface 22b are cylindrical surfaces. The sleeve 22 is fixed to the outer peripheral surface 20a of the rotating shaft 20 in a non-rotatable manner by, for example, interference fit.

[0023] The magnets 24 are arranged on the radially outer side of the sleeve 22. In the present embodiment, a total of four magnets 24 are arranged at substantially equal intervals in the circumferential direction. Each magnet 24 is made of, for example, ferrite or neodymium and has an arcuate outer surface 28.

[0024] The reinforcing member 26 is cylindrical and surrounds the magnet 24 from the radially outer side in contact with the outer surface 28 of the magnet 24, and the magnet 24 is clamped between the reinforcing member 26 and the sleeve 22. The reinforcing member 26 is made of a reinforcing resin such as glass fiber reinforced resin (GFRP) or carbon fiber reinforced resin (CFRP), for example.

[0025] The inner peripheral surface 26a of the reinforcing member 26 is cylindrical, as Figures 1 to 3 shown, in the state where the rotor 12 is assembled, the inner peripheral surface 26a of the reinforcing member 26 has the same radius of curvature as the outer surface 28 of each magnet 24. That is, in the state where the rotor 12 is assembled, the inner peripheral surface 26a of the reinforcing member 26 and the outer surface 28 of the magnet 24 have the same shape, and substantially the entire area of the outer surface 28 is in surface contact with the inner peripheral surface 26a.

[0026] Next, a method for manufacturing the rotor 12 will be briefly described. First, the manufacturer prepares the sleeve 22, a plurality of magnets 24, and the reinforcing member 26. At this time, the inner peripheral surface 26a of the prepared reinforcing member 26 may also have a radius of curvature smaller than the radius of curvature of the outer surface 28 of the magnet 24. Next, the manufacturer arranges the magnets 24 on the radially outer side of the sleeve 22, and inserts the reinforcing member 26 into the radially outer side of the plurality of magnets 24 so as to surround the plurality of magnets 24. Next, the manufacturer uses an interference fit method such as hot press fit or cold shrink fit to insert the rotating shaft 20 into the inside of the sleeve 22 and fix the sleeve 22 to the outer peripheral surface 20a of the rotating shaft 20.

[0027] At this time, the reinforcing member 26 is elastically deformed by the magnet 24 in a manner of slightly expanding radially outward, and as a reaction force thereof, the magnet 24 is fastened radially inward. The amount of elastic deformation of the reinforcing member 26 radially outward at this time is referred to as the interference amount. In this way, the reinforcing member 26 is elastically deformed with a predetermined interference amount and the magnet 24 is fastened, so that the magnet 24 can be firmly held between the sleeve 22 and the reinforcing member 26.

[0028] As Figure 2 and Figure 3 shown, each magnet 24 has a circumferential central portion 30 and circumferential end portions 32 and 33 provided on both circumferential sides of the central portion 30. The central portion 30 has an inner surface (first inner surface) 30a that abuts against the outer peripheral surface 22a of the sleeve 22. The inner surface 30a is an arc surface that extends along the circumference from an end edge 34 on one circumferential side to an end edge 36 on the other circumferential side, and the entire area thereof is in surface contact with the outer peripheral surface 22a of the sleeve 22.

[0029] As Figures 1 to 3 shown, in a state where the rotor 12 is assembled, the inner surface 30a has the same radius of curvature as the outer peripheral surface 22a of the sleeve 22. Here, in the present embodiment, the circumferential width of the central portion 30 is set to be more than 1 / 3 of the entire circumferential width of the magnet 24. However, it is not limited thereto, and the circumferential width of the central portion 30 may also be set to a value smaller than 1 / 3 of the entire circumferential width of the magnet 24.

[0030] The end portion 32 is integrally provided on one circumferential side of the central portion 30 and has a radial thickness smaller than the radial thickness of the central portion 30, so that a gap 38 is formed between the end portion 32 and the sleeve 22. More specifically, the end portion 32 has an inner surface (second inner surface) 32a and an end surface 32b on one circumferential side. The inner surface 32a is connected to the inner surface 30a of the central portion 30 at the end edge 34 and extends from the end edge 34 to the end surface 32b in a manner of forming the gap 38.

[0031] In the present embodiment, the inner surface 32a is a plane that extends in a manner such that the gap 38 widens as it goes from the end edge 34 toward the end surface 32b. The end surface 32b is a plane that defines the circumferential end edge on one circumferential side of the magnet 24. The end portion 32 can be defined as a portion of the magnet 24 on the circumferential side of the end edge 34 (or, a circumferential section of the magnet 24 that is separated from the sleeve 22 by the gap 38).

[0032] The end portion 33 is integrally provided on the other side in the circumferential direction of the central portion 30, and has a thickness in the radial direction smaller than that of the central portion 30, similarly to the end portion 32. As a result, a gap 40 is formed between the end portion 33 and the sleeve 22. The end portion 33 has a shape symmetrical to the end portion 32 with respect to a hypothetical plane passing through the center of the central portion 30 and the axis A and parallel to the axial direction. Specifically, the end portion 33 has an inner surface (second inner surface) 33a and an end face 33b on the other side in the circumferential direction. The inner surface 33a is connected to the inner surface 30a of the central portion 30 at the edge 36, and extends from the edge 36 to the end face 33b so as to form the gap 40.

[0033] In the present embodiment, the inner surface 33a is a plane extending in such a manner that the gap 40 widens as it goes from the edge 36 toward the end face 33b. The end face 33b is a plane, and defines the edge on the other side in the circumferential direction of the magnet 24. The end portion 33 can be defined as the portion of the magnet 24 on the other side in the circumferential direction of the edge 36 (or, the circumferential section of the magnet 24 separated from the sleeve 22 with the gap 40 therebetween).

[0034] The outer surface 28 of the magnet 24 is defined by the outer surface of the central portion 30 and the outer surfaces of the end portion 32 and the end portion 33. In the present embodiment, the end portion 32 and the end portion 33 are separated radially outward from the sleeve 22 over their entire regions. As a result, the gap 38 and the gap 40 are formed over the entire axial regions of the end portion 32 and the end portion 33.

[0035] As described above, in the present embodiment, the end portion 32 and the end portion 33 of the magnet 24 have a thickness in the radial direction smaller than that of the central portion 30, so that the gap 38 and the gap 40 are formed between the end portion 32 and the end portion 33 and the sleeve 22. According to this structure, the magnetic flux generated in the end portion 32 and the end portion 33 is reduced compared to the central portion 30. Thus, when the motor 10 operates, the end portion 32 and the end portion 33 can alleviate the degree of change (partial differential of magnetic flux) of the magnetic flux linked with the coil 18 of the opposing stator 14 when passing through the coil 18. Thereby, the cogging torque generated when the motor 10 operates and the heat generation due to eddy currents can be suppressed.

[0036] On the other hand, the outer surface 28 of the magnet 24 has the same shape as the inner peripheral surface 26a of the reinforcing member 26, and is in surface contact with the inner peripheral surface 26a over substantially the entire region. According to this structure, the interference amount of the reinforcing member 26 can be minimized. Therefore, breakage of the reinforcing member 26 can be prevented, and the magnet 24 can be fastened with an appropriate interference amount by the reinforcing member 26. Thereby, the motor 10 can be advantageously applied to high-speed rotation. In addition, since the interference amount of the reinforcing member 26 can be easily ensured, the manufacturing process of the rotor 12 can be facilitated.

[0037] In addition, the reinforcing member 26 can equalize the force for fastening the magnet 24 in the circumferential direction. Therefore, it is possible to prevent the end portions 32 and 33 from being displaced radially inward due to excessive force applied to the end portions 32 and 33 of the magnet 24 from the reinforcing member 26, so that the gaps 38 and 40 disappear. Thus, according to the present embodiment, it is possible to simultaneously achieve suppression of cogging torque and heat generation, application to high-speed rotation, facilitation of manufacturing processes, and prevention of disappearance of the gaps 38 and 40 due to deformation of the magnet 24.

[0038] In addition, in the present embodiment, the inner surface 30a of the central portion 30 of the magnet 24 is an arc surface having the same radius of curvature as the outer peripheral surface 22a of the sleeve 22. According to this structure, the contact area between the inner surface 30a and the outer peripheral surface 22a is increased, and thus, the friction generated between the inner surface 30a and the outer peripheral surface 22a can be increased. As a result, it is possible to effectively prevent the magnet 24 from deviating from the sleeve 22 when the motor 10 operates.

[0039] Moreover, in the present embodiment, the width of the central portion 30 in the circumferential direction is set to be 1 / 3 or more of the entire width of the magnet 24 in the circumferential direction. Thus, when the ratio of the width of the central portion 30 in the circumferential direction and the width of the magnet 24 in the circumferential direction is set, the contact area between the inner surface 30a and the outer peripheral surface 22a can be sufficiently ensured, and thus, it is possible to more effectively prevent the magnet 24 from deviating from the sleeve 22 when the motor 10 operates.

[0040] In addition, the inner surface 32a of the end portion 32 or the inner surface 33a of the end portion 33 is not limited to a flat surface and may be a curved surface. Refer to Figure 4 and Figure 5 to describe such an embodiment. Figure 4 The rotor 50 shown is different from the above-described rotor 12 in terms of the structure of the magnet 52. Specifically, the magnet 52 has a central portion 30, an end portion 54 on one side in the circumferential direction, and an end portion (not shown) on the other side in the circumferential direction.

[0041] The end portion 54 has a thickness in the radial direction smaller than the thickness in the radial direction of the central portion 30. More specifically, the end portion 54 has an end surface 32b on one side in the circumferential direction and an inner surface (second inner surface) 54a. The inner surface 54a extends from the end edge 34 to the end surface 32b so as to form a gap 38. Here, in the present embodiment, the inner surface 54a is a concave curved surface that is recessed toward the inside of the end portion 54 and extends in a curved shape so that the gap 38 widens as it goes from the end edge 34 toward the end surface 32b.

[0042] The inner surface 54a can be, for example, an arc surface having a predetermined radius of curvature, or it can also be an arbitrary curved surface (such as a combination of multiple arc surfaces). Additionally, although the other end portion of the magnet 52 in the circumferential direction is not shown, it has a shape symmetrical to the end portion 54 with respect to a hypothetical plane passing through the center of the central portion 30 and the axis A and parallel to the axial direction, and has an inner surface (second inner surface) that is a concave curved surface similar to the end portion 54.

[0043] In the present embodiment, since the inner surface 54a is a concave curved surface, the thickness of the magnet 52 decreases in an asymptotic line shape as it goes from the edge 34 toward the end face 32b. According to this structure, when the motor 10 operates, the end portion 54 (and the other end portion in the circumferential direction) can further alleviate the degree of change (partial differential of magnetic flux) of the magnetic flux linked with the coil 18 when passing through the coil 18 of the opposing stator 14. Thereby, the cogging torque and heat generation can be more effectively suppressed.

[0044] On the other hand, the outer surface 28 of the magnet 52 is in surface contact with the inner circumferential surface 26a of the reinforcing member 26 in substantially the entire area. Therefore, similar to the above-described embodiment, it is possible to simultaneously achieve suppression of cogging torque and heat generation, application to high-speed rotation, facilitation of the manufacturing process, and prevention of the disappearance of the gaps 38 and 40 due to the deformation of the magnet 52.

[0045] Figure 5 The shown rotor 60 is different from the above-described rotor 50 in terms of the inner surface (second inner surface) 64a of the end portion 64 of the magnet 62. Specifically, the inner surface 64a is a convex curved surface bulging outward from the end portion 64, and extends in such a way that the gap 38 widens as it goes from the edge 34 toward the end face 32b. Due to this gap 38, the end portion 64 has a radial thickness smaller than the radial thickness of the central portion 30. The inner surface 64a can be, for example, an arc surface having a predetermined radius of curvature, or it can also be an arbitrary curved surface.

[0046] Additionally, although the other end portion of the magnet 62 in the circumferential direction is not shown, it has a shape symmetrical to the end portion 64 with respect to a hypothetical plane passing through the center of the central portion 30 and the axis A and parallel to the axial direction, and has an inner surface (second inner surface) that is a convex curved surface similar to the end portion 64. According to the present embodiment, since it has the convex curved surface inner surface 64a, Figure 3 and Figure 4 compared with the embodiment shown, it is possible to locally increase the radial thickness of the end portion 64, and thereby improve the strength of the end portion 64.

[0047] In addition, in the above-described embodiment, the case where the circumferential end portions 32, 33, 54, 64 of the magnets 24, 52, 62 are separated from the sleeve 22 over their entire regions has been described. However, it is also possible that a part of the circumferential end portion of the magnet abuts against the sleeve 22. Refer to Figure 6 and Figure 7 such an embodiment will be described.

[0048] Figure 6 and Figure 7 The rotor 70 shown is different from the above-described rotor 12 in terms of the magnet 72. Specifically, the magnet 72 has a circumferential central portion 30, a circumferentially one-side end portion 74, and a circumferentially other-side end portion (not shown). The end portion 74 has a circumferentially one-side end face 32b and an inner surface (second inner surface) 76 that extends from the end edge 34 to the end face 32b. The inner surface 76 includes a radial surface 76a that extends radially outward from the end edge 34 and a circumferential surface 76b that extends circumferentially one side from the radially outer end edge of the radial surface 76a. A gap 78 is formed between the circumferential surface 76b and the outer peripheral surface 22a of the sleeve 22.

[0049] Here, in the present embodiment, a protrusion 77 that extends radially inward from the circumferential surface 76b is formed on the circumferential surface 76b of the end portion 74. The protrusion 77 extends circumferentially from the radial surface 76a to the end face 32b, and its radially inner end face 77a abuts against the outer peripheral surface 22a of the sleeve 22. By means of this protrusion 77, the gap 78 is divided in the front and rear in the axial direction.

[0050] Thus, the end portion 74 has a radially smaller thickness than the radially thickness of the central portion 30 in the axial interval where the gap 78 is formed (in other words, the axial interval other than the protrusion 77). In addition, although the circumferentially other-side end portion of the magnet 72 is not shown, it has a shape that is symmetric to the end portion 74 with respect to a hypothetical plane passing through the center of the central portion 30 and the axis A and parallel to the axial direction, and has an inner surface and a protrusion corresponding to the inner surface 76 and the protrusion 77.

[0051] In the present embodiment, since the end portion 74 (and the circumferentially other-side end portion) has a radially smaller thickness than the radially thickness of the central portion 30 in the portion where the gap 78 is formed, similarly to the above-described embodiment, when the end portion 74 (and the circumferentially other-side end portion) passes through the coil 18 of the opposing stator 14, the degree of change (partial differential of magnetic flux) of the magnetic flux linked with the coil 18 can be alleviated. Thereby, the cogging torque and heat generation can be more effectively suppressed.

[0052] On the other hand, the outer surface 28 of the magnet 72 is in surface contact with the inner peripheral surface 26a of the reinforcing member 26 over substantially the entire area. Therefore, as in the above-described embodiment, it is possible to simultaneously suppress cogging torque and heat generation, apply it to high-speed rotation, facilitate the manufacturing process, and prevent the disappearance of the gap 78 due to deformation of the magnet 72.

[0053] Moreover, the protrusion 77 abuts against the sleeve 22. Therefore, compared with the case where the protrusion 77 is not formed, the contact area between the magnet 72 and the sleeve 22 can be increased, and thereby, the friction between the magnet 72 and the sleeve 22 can be increased. As a result, it is possible to effectively prevent the magnet 72 from deviating from the sleeve 22 when the motor 10 operates. In addition, the gap 78 is reliably ensured by the protrusion 77, and therefore, it is possible to more reliably prevent the disappearance of the gap 78 due to deformation of the magnet 72.

[0054] In addition, in the above-described embodiment, the case where the sleeve 22 has a cylindrical shape has been described. However, the sleeve may have a polygonal outer shape, for example. Refer to Figure 8 and Figure 9 such an embodiment will be described. Figure 8 and Figure 9 The rotor 80 shown has a rotating shaft 20, a sleeve 82, a plurality of magnets 84, and a reinforcing member 26.

[0055] The sleeve 82 is tubular and has a cylindrical inner peripheral surface 88 and a hexagonal (e.g., regular hexagonal) outer peripheral surface 90. The outer peripheral surface 90 is formed by being divided by a total of six flat surfaces 90a corresponding to the respective sides of the hexagon. The magnets 84 are arranged on the radially outer side of the sleeve 82. In the present embodiment, a total of six magnets 84 are arranged on the respective flat surfaces 90a so as to be substantially equally spaced in the circumferential direction. Each magnet 84 has an arcuate outer surface 28. The reinforcing member 26 surrounds the magnet 84 such that its inner peripheral surface 26a abuts against the outer surface 28 of each magnet 84, and the magnet 84 is clamped between the reinforcing member 26 and the sleeve 82.

[0056] As Figure 9 shown, the magnet 84 has a central portion 96 in the circumferential direction and circumferential end portions 98 and 100 provided on both circumferential sides of the central portion 96. The central portion 96 has an inner surface (first inner surface) 96a that abuts against the flat surface 90a of the sleeve 82. The inner surface 96a is a flat surface that extends in the circumferential direction from an end edge 102 on one circumferential side to an end edge 104 on the other circumferential side, and its entire area is in surface contact with the flat surface 90a of the sleeve 82.

[0057] Here, in the circumferential direction of the central portion 96 (or, Figure 9The width in the left - right direction of the paper surface is set to be more than 1 / 3 of the entire width in the circumferential direction of the magnet 84. However, it is not limited to this, and the width in the circumferential direction of the central portion 96 may also be set to a value smaller than 1 / 3 of the entire width in the circumferential direction of the magnet 84.

[0058] The end portion 98 is integrally provided on one side in the circumferential direction of the central portion 96 and has a thickness in the radial direction smaller than the thickness in the radial direction of the central portion 96. Thus, a gap 106 is formed between the end portion 98 and the sleeve 82. More specifically, the end portion 98 has an inner surface (second inner surface) 98a and an end surface 98b on one side in the circumferential direction. The inner surface 98a is connected to the inner surface 96a of the central portion 96 at the end edge 102 and extends from the end edge 102 to the end surface 98b in such a manner as to form the gap 106.

[0059] In the present embodiment, the inner surface 98a is a plane inclined with respect to the plane 90a and the plane 96a such that the gap 106 widens as it goes from the end edge 102 toward the end surface 98b. The end surface 98b is a plane substantially orthogonal to the plane 90a and the plane 96a and demarcates the end edge on one side in the circumferential direction of the magnet 84. The end portion 98 can be defined as the portion of the magnet 84 on the one side in the circumferential direction of the end edge 102 (that is, Figure 9 the left side of the paper surface in the figure) (or, the circumferential section of the magnet 84 separated from the sleeve 82 across the gap 106).

[0060] The end portion 100 is integrally provided on the other side in the circumferential direction of the central portion 96 and, similarly to the end portion 98, has a thickness in the radial direction smaller than the thickness in the radial direction of the central portion 96. Thus, a gap 108 is formed between the end portion 100 and the sleeve 82. The end portion 100 has a shape symmetric to the end portion 98 with respect to an imaginary plane passing through the center of the central portion 96 and the axis A and parallel to the axial direction.

[0061] Specifically, the end portion 100 has an end surface 100b that demarcates the end edge on the other side in the circumferential direction of the magnet 84 and an inner surface (second inner surface) 100a that is a plane extending from the end edge 104 to the end surface 100b in such a manner as to form the gap 108. The outer surface 28 of the magnet 84 is demarcated by the outer surface of the central portion 96 and the outer surfaces of the end portion 98 and the end portion 100.

[0062] In the present embodiment, the end portions 98 and 100 of the magnet 84 have a thickness in the radial direction that is smaller than the thickness in the radial direction of the central portion 96, thereby forming a gap 106 and a gap 108 between the end portions 98 and 100 and the sleeve 82. According to this structure, similarly to the above-described embodiment, when the motor 10 operates, the end portions 98 and 100 can alleviate the degree of change (partial differential of magnetic flux) of the magnetic flux linked to the coil 18 of the opposing stator 14 when passing through the coil 18. Thereby, cogging torque and heat generation can be suppressed.

[0063] On the other hand, the outer surface 28 of the magnet 84 is in surface contact with the inner peripheral surface 26a of the reinforcing member 26 over substantially the entire region thereof. Therefore, similarly to the above-described embodiment, it is possible to simultaneously achieve suppression of cogging torque and heat generation, application to high-speed rotation, facilitation of the manufacturing process, and prevention of disappearance of the gaps 106 and 108 due to deformation of the magnet 84.

[0064] In addition, in the above-described embodiment, the case where the sleeves 22 and 82 are cylindrical has been described. However, the sleeve may be divided into a plurality of segments in the circumferential direction. Figure 10 An embodiment showing this is presented. Figure 10 The rotor 110 shown is different from the above-described rotor 12 in terms of the sleeve 112.

[0065] The sleeve 112 has a plurality of sleeve segments 114 divided in the circumferential direction. In the present embodiment, a total of four sleeve segments 114 are arranged at substantially equal intervals in the circumferential direction. Each sleeve segment 114 has an inner surface 114a that abuts against the outer peripheral surface 20a of the rotating shaft 20 and an outer surface 114b on the side opposite to the inner surface 114a. The inner surface 114a and the outer surface 114b are arc surfaces that are substantially parallel to each other.

[0066] Magnets 24 are arranged one-to-one on the outer surface 114b of the sleeve segment 114. A gap 38 and a gap 40 are formed between the end portions 32 and 33 of the magnet 24 and the outer surface 114b. According to the present embodiment, similarly to the above-described embodiment, it is possible to simultaneously achieve suppression of cogging torque and heat generation, application to high-speed rotation, facilitation of the manufacturing process, and prevention of disappearance of the gaps 38 and 40 due to deformation of the magnet 24.

[0067] In addition, it is also possible that the connecting portions between the inner surfaces 30a, 96a of the central portions 30, 96 and the inner surfaces 32a, 33a, 54a, 64a, 76, 98a, 100a of the end portions 32, 33, 54, 64, 74, 98, 100 have chamfered portions or rounded corners. Refer to Figure 11 and Figure 12 for an explanation of such a form.

[0068] Figure 11 The rotor 50' shown is a modified example of the above-mentioned rotor 50. In this rotor 50', a chamfered portion 116 is formed at the connecting portion between the inner surface 54a of the end portion 54 of the magnet 52' and the inner surface 30a of the central portion 30. Thereby, it is possible to prevent a sharp corner portion from being formed at the connecting portion between the inner surface 54a and the inner surface 30a, and the inner surface 54a and the inner surface 30a can be connected relatively smoothly.

[0069] On the other hand, in Figure 12 In the rotor 50'' shown, a rounded corner portion 118 (so-called rounded corner) is formed at the connecting portion between the inner surface 54a of the end portion 54 of the magnet 52'' and the inner surface 30a of the central portion 30. Thereby, it is possible to prevent a sharp corner portion from being formed at the connecting portion between the inner surface 54a and the inner surface 30a, and the inner surface 54a and the inner surface 30a can be connected smoothly.

[0070] As Figure 11 and Figure 12 shown, the inner surface 54a and the inner surface 30a are connected smoothly. Thus, when the motor 10 operates, when the end portion 54 passes through the coil 18 of the opposing stator 14, it is possible to more effectively mitigate the degree of change (partial differential of magnetic flux) of the magnetic flux linked to the coil 18, and it is possible to prevent stress concentration from occurring at the connecting portion between the inner surface 54a and the inner surface 30a. In addition, it can be understood that Figure 11 the chamfered portion 116 shown or Figure 12 the rounded corner portion 118 shown can be applied to the above-mentioned rotors 12, 60, 70, 80, or 110.

[0071] In addition, in the above-described embodiment, the case where the entire region of the outer surface 28 of the magnets 24, 52, 52', 52'', 62, 72, 84 is in surface contact with the inner peripheral surface 26a of the reinforcing member 26 has been described. However, it is also possible that the outer surface of the magnet is separated from the inner peripheral surface of the reinforcing member at its circumferential end. Refer to Figure 13 to describe such an embodiment.

[0072] Figure 13 The rotor 12' shown is a modified example of the above-mentioned rotor 12, and is different from the rotor 12 in terms of the end portion 32'. Specifically, the end portion 32' has an outer surface 32c in addition to the inner surface 32a and the end surface 32b. The outer surface 32c extends from the circumferentially upper end edge 120 of the outer surface 30b of the central portion 30 to form a gap 122 to the end surface 32b.

[0073] Thus, in the present embodiment, the end portion 32' is separated from the inner peripheral surface 26a of the reinforcing member 26. On the other hand, the entire region of the outer surface 30b of the central portion 30 is in surface contact with the inner peripheral surface 26a of the reinforcing member 26. In addition, although not shown, the end portion 33' on the other side in the circumferential direction of the magnet 24' may also have an outer surface corresponding to the outer surface 32c. Further, it can be understood that the outer surface 32c of the end portion 32' of the present embodiment and the gap 122 formed by the outer surface 32c can be applied to the forms shown in the above-described rotors 50, 50', 50", 60, 70, 80, or 110.

[0074] In addition, the number of the magnets 24, 24', 52, 52', 52", 62, 72, 84 is not limited to the above-described form and can be any number. Further, the end portions 33, 100 on the other side in the circumferential direction of the magnets 24, 24', 52, 52', 52", 62, 72, 84 may be omitted so that only the end portions 32, 32', 54, 64, 74, 98 on one side in the circumferential direction of the magnets 24, 24', 52, 52', 52", 62, 72, 84 are separated from the sleeves 22, 82, 112 in a manner of forming the gaps 38, 78, 106. That is, in this case, the end portions of the magnets on the other side in their circumferential direction are in contact with the sleeves. Further, the features of the above-described various embodiments can be combined. For example, the rib portion 77 shown in Figure 6 can be applied to the embodiment shown in Figures 3 to 5 .

[0075] As described above, the present disclosure has been described by way of embodiments, but the above-described embodiments are not intended to limit the invention of the claims.

Claims

1. A rotor, which is a rotor of an electric motor, wherein, the rotor includes: a sleeve fixed to the radially outer side of the rotating shaft; a plurality of magnets disposed on the radially outer side of the sleeve; and a reinforcing member in a cylindrical shape, which surrounds the plurality of magnets in a manner of abutting against the outer surfaces of the plurality of magnets, and clamps the plurality of magnets between the reinforcing member and the sleeve, each of the plurality of magnets has: a central portion in the circumferential direction, which abuts against the sleeve; and an end portion in the circumferential direction, which has a thickness smaller than that of the central portion, and a gap is formed between the end portion and the sleeve, wherein the end portion of the magnet has: a second inner surface extending to form the gap; and a rib portion extending radially inward from the second inner surface to abut against the sleeve.

2. The rotor according to claim 1, wherein, the central portion of the magnet has a first inner surface abutting against the sleeve, the second inner surface is connected to the first inner surface and extends from the first inner surface to the circumferential edge of the magnet to form the gap.

3. The rotor according to claim 2, wherein, the outer surface of the sleeve is a cylindrical surface, the first inner surface is an arc surface having the same radius of curvature as the outer surface of the sleeve.

4. The rotor according to claim 2 or 3, wherein, the second inner surface extends in a plane or a curved surface such that the gap widens as it goes from the first inner surface toward the edge.

5. The rotor according to claim 4, wherein, the curved surface is a concave curved surface.

6. The rotor according to claim 2 or 3, wherein, a chamfered portion or a rounded corner is provided at the connecting portion between the first inner surface and the second inner surface.

7. The rotor according to any one of claims 1 to 3, wherein, a second gap is formed between the end portion of the magnet and the reinforcing member.

8. The rotor according to any one of claims 1 to 3, wherein, the inner surface of the reinforcing member is a cylindrical surface, the outer surface of the magnet is an arc surface having the same radius of curvature as the inner surface of the reinforcing member.

9. The rotor according to any one of claims 1 to 3, wherein, the width of the central portion of the magnet in the circumferential direction is 1 / 3 or more of the entire width of the magnet in the circumferential direction.

10. An electric motor, wherein, the electric motor includes the rotor according to any one of claims 1 to 9.

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