Motor

Abstract

To improve output torque.SOLUTION: A motor has a rotor which comprises a yoke, a plurality of first magnets, and a plurality of second magnets. The yoke has a plurality of frames each having an outer circumferential part. Each of the plurality of first magnets is disposed in each of the plurality of frames. In a circumferential direction, each of the second magnets is located between two adjacent ones of the plurality of frames. In the circumferential direction, each of the second magnets has a portion larger than a width between the outer circumferential parts of the two frames.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a motor. [Background technology]

[0002] Halbach-array motors are known, in which multiple magnets with different magnetic flux directions are arranged on the surface of a rotor yoke. For example, in Halbach-array motors with an inner rotor structure, a technique is known in which the magnets are embedded in a magnet holding member to prevent the magnets from popping out due to centrifugal force during rotation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-006545 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-207067 [Patent Document 3] International Publication No. 2014 / 115655 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a Halbach array motor, the amount of magnetic flux flowing from the magnet to the stator may decrease, resulting in a decrease in the motor's output torque.

[0005] One object of the present invention is to provide a motor capable of improving output torque. [Means for solving the problem]

[0006] In one embodiment, a motor includes a rotor having a yoke, a plurality of first magnets, and a second magnet. The yoke includes a plurality of frames having an outer periphery, the plurality of first magnets are disposed within the frames, and the second magnet is located between two adjacent frames in the circumferential direction. The second magnet includes a portion in the circumferential direction that is larger than the width between the outer peripheries of the two frames. The frame has a portion in the circumferential direction that is wider than the width of the outer periphery of the frame, the portion being located radially inward of the outer periphery.

[0007] According to one aspect, the output torque can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an example of a motor according to an embodiment. [Figure 2] FIG. 2 is a partial top view showing an example of a motor according to an embodiment. [Figure 3] FIG. 3 is an enlarged top view showing an example of a motor according to an embodiment. [Figure 4] FIG. 4 is an enlarged top view showing an example of a yoke in the embodiment. [Figure 5] FIG. 5 is an enlarged top view showing an example of a rotor in the first modified example. [Figure 6] FIG. 6 is an enlarged top view showing an example of a rotor in the second modified example. [Figure 7] FIG. 7 is an enlarged top view showing an example of a rotor in the third modified example. [Figure 8] FIG. 8 is an enlarged top view showing an example of a rotor in the fourth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the motor disclosed herein will be described in detail with reference to the drawings. Note that the dimensional relationships and ratios of elements in the drawings may differ from reality. The dimensional relationships and ratios may also differ between the drawings. To facilitate understanding of the description, each drawing may illustrate a coordinate system in which the direction in which the motor's rotation shaft extends is the axial direction.

[0010] [Embodiment] First, a motor according to an embodiment will be described with reference to FIG. 1. FIG. 1 is a perspective view showing an example of a motor according to an embodiment. As shown in FIG. 1, the motor 1 according to the embodiment includes a stator 10 and a rotor 20. The motor 1 according to the embodiment is, for example, a so-called flat motor in which the length in the radial direction of the stator is greater than the length in the axial direction. The motor 1 is, for example, a frameless motor. The motor 1 transmits driving force to the outside via, for example, a rotating shaft (not shown).

[0011] As shown in Fig. 1, the stator 10 includes a stator core 11, an insulator 12, and a coil 13. The stator core 11 is formed by stacking a plurality of plate-shaped metal members, such as silicon steel plates or soft magnetic steel plates such as electromagnetic steel plates, in the axial direction. The insulator 12 is formed of an insulating material, such as resin. The coil 13 is wound around the stator core 11, for example, via the insulator 12.

[0012] As shown in Figures 1 and 2, the rotor 20 is disposed radially inward of the stator 10. That is, the motor 1 in the embodiment is, for example, an inner rotor type motor. Figure 2 is a partial top view showing an example of the motor in the embodiment. Figure 2 is a top view of the portion indicated by frame F1 in Figure 1. Note that in Figure 2 and subsequent figures, the stator 10 may be illustrated in a simplified form. For example, the insulator 12 is not illustrated in Figure 2.

[0013] 1 and 2, the rotor 20 includes a yoke 30, a plurality of first magnets 41, and a plurality of second magnets 42. In the following description, the first magnets 41 and the second magnets 42 may be referred to as magnets 40 when there is no need to distinguish between them.

[0014] The yoke 30 is a yoke made of, for example, iron, and includes an annular portion 36 and a frame 39 surrounding a hole 38. As shown in Fig. 2, the annular portion 36 extends in the circumferential direction, and the multiple frames 39 are formed, for example, aligned at equal intervals in the circumferential direction. In this embodiment, for example, 20 frames 39A to 39T are formed.

[0015] The magnet 40 is a magnet that extends in the axial direction, and may be a sintered magnet such as a ferrite magnet or a neodymium magnet. The axial length of the magnet 40 is, for example, approximately the same as the axial length of the yoke 30. In this case, as shown in FIG. 2, the magnet 40 is arranged so that the axial end face of the magnet 40 and the axial end face of the yoke 30 are approximately flush with each other.

[0016] As shown in Figures 2 to 4, the first magnet 41 is disposed in a hole 38 surrounded by a frame 39, and the second magnet 42 is disposed in a gap 35 sandwiched between adjacent frames 39 in the circumferential direction. Figure 3 is an enlarged top view showing an example of a motor in an embodiment. Figure 4 is an enlarged top view showing an example of a yoke in an embodiment. Figure 3 is an enlarged view of a portion indicated by frame F2 in Figure 2. Figure 4 shows the yoke 30 before the first magnet 41 and second magnet 42 shown in Figure 3 are disposed.

[0017] 4, the frame 39 is formed from an outer peripheral portion 31, a pair of side portions 32 and 33, and an inner peripheral portion 34. For example, the frame 39A is formed from an outer peripheral portion 31A, a pair of side portions 32A and 33A, and the inner peripheral portion 34. In the embodiment, the inner peripheral portion 34 is formed by the outer peripheral portion of the annular portion 36. In this case, the hole 38 is surrounded by the outer peripheral portion 31 and the annular portion 36 in the radial direction, and is surrounded by the pair of side portions 32 and 33 in the circumferential direction.

[0018] As shown in Fig. 4, a gap 35 is sandwiched between two frames 39 adjacent to each other in the circumferential direction. More specifically, a gap 35 is formed in the circumferential direction by a side portion 32 of one frame 39 and a side portion 33 of another frame 39. For example, gap 35A in Fig. 4 is sandwiched between a side portion 32A of frame 39A and a side portion 33T of frame 39T. The yoke 30 in this embodiment has the same number of gaps 35A to 35T as the number of frames 39.

[0019] The side portions 32 and 33 extend radially outward from the annular portion 36. In this embodiment, the side portions 32 and 33 are formed to be inclined relative to the radial direction, as shown by arrows a1 and a2 in FIG. 4. More specifically, the side portions 32 and 33 are inclined outward relative to the hole 38 and inward relative to the gap 35. For example, the side portion 32A is inclined outward (toward the left in the drawing) relative to the hole 38A.

[0020] In this case, the circumferential width of the gap 35 differs between the radially inner and outer sides. Specifically, the circumferential width Dc of the gap 35 on the radially outer side is larger than the circumferential width Dd of the gap 35 on the radially inner side. In the embodiment, the circumferential width of the gap 35 varies linearly with respect to the radial direction, being minimum on the radially outer side and maximum on the radially inner side.

[0021] In the embodiment, the side portions 32 and 33 are formed to have a constant size (width) in the circumferential direction. In this case, the size (width) in the circumferential direction of the hole 38 sandwiched between the side portions 32 and 33 also differs between the radially inner and outer sides. Specifically, the circumferential width Da of the hole 38 on the radially outer side is larger than the radially inner circumferential width Db of the hole 38.

[0022] The first magnet 41 is inserted, for example, axially into the hole 38 surrounded by the frame 39. The second magnet 42 is inserted axially into the gap 35. In this case, the size (height) H2 of the second magnet 42 in the radial direction is larger than the size (height) H1 of the first magnet 41 in the radial direction. Note that the outer peripheral surface 45 of the second magnet 42 is formed, for example, to be substantially flush with the outer peripheral portion 31 of the frame 39, as shown in FIG. 3. In other words, the distance from the center of the rotor 20 to the outer peripheral surface 45 of the second magnet 42 and the distance from the center of the rotor 20 to the outer peripheral portion 31 of the frame 39 are formed to be the same in the radial direction.

[0023] In the embodiment, the outer peripheral surface 45 of the second magnet 42 directly faces the stator 10 in the radial direction. On the other hand, the first magnet 41 faces the stator 10 in the radial direction via the outer peripheral portion 31 of the frame 39. In this case, the distance D2 in the radial direction between the outer peripheral surface 45 of the second magnet 42 and the stator 10 is smaller than the distance D1 in the radial direction between the first magnet 41 and the stator 10.

[0024] The size (width) Wp of the maximum portion in the circumferential direction of the second magnet 42 is larger than the size (width) Dc of the minimum portion in the circumferential direction of the gap 35. In the embodiment, the circumferential width of the second magnet 42 is maximum, for example, near the inner circumferential surface 46. This prevents the second magnet 42 from protruding radially outward from the gap 35.

[0025] As described above, the motor 1 in this embodiment includes a rotor 20 having a yoke 30, a plurality of first magnets 41, and a second magnet 42. The yoke 30 includes a plurality of frames 39 each having an outer periphery 31. The plurality of first magnets 41 are disposed within each of the frames 39. The second magnet 42 is located in a gap 35 between two adjacent frames 39 in the circumferential direction. The second magnet 42 includes a portion 46 in the circumferential direction that is larger than the width Dc of the outer peripheries of the two frames 39. This configuration increases the magnetic flux flowing from the magnet 40 to the stator 10, thereby improving the output torque.

[0026] [Variations] Although the configuration of the embodiment has been described above, the embodiment is not limited thereto. For example, the frame 39 of the yoke 30 and the number of gaps 35 formed in the yoke 30 are not limited to those shown in the embodiment. Furthermore, the circumferentially protruding portions of the frame 39 of the yoke 30 are not limited to the side portions 32 and 33 formed at an angle relative to the radial direction. For example, the circumferentially protruding portions may be formed integrally with the annular portion 36 as in the configuration of the embodiment, or a separate member may be formed as an engaging portion and disposed radially outside the annular portion 36. Note that the side portions 32 and 33 are engaging portions that engage with the first magnet 41 and the second magnet 42. Furthermore, the material of the yoke is not limited to iron, but may be other magnetic materials.

[0027] Furthermore, it is sufficient that the magnet 40 does not protrude further in the axial direction than the yoke 30. In this case, the axial length of the magnet 40 may be, for example, shorter than the axial length of the yoke 30. Furthermore, although the motor 1 in the embodiment is an inner rotor type flat motor, this is not limiting and the motor may be, for example, an outer rotor type motor, and the axial length of the motor may be longer than the radial length.

[0028] Furthermore, magnet 40 is not limited to a molded magnet such as a sintered magnet. For example, a bonded magnet or the like may be molded into any shape in gap 35 and hole 38 using an injection molding machine or the like. That is, instead of a configuration in which molded magnet 40 is fitted axially into hole 38 of yoke 30 and gap 35, magnet 40 may be molded directly in gap 35 and hole 38.

[0029] Furthermore, the portion of the gap with the smallest circumferential width (hereinafter, sometimes referred to as the minimum portion of the gap) may be formed in a portion other than the portion facing the outer peripheral portion 31 of the frame 39, as shown in FIG. 5. Furthermore, the portion of the second magnet with the largest circumferential width (hereinafter, sometimes referred to as the maximum portion of the second magnet) may also be formed in a portion other than the radially inner side, as shown in FIG. 6. Furthermore, the size of the gap in the circumferential direction may change nonlinearly. FIG. 5 is an enlarged top view showing an example of a rotor in a first modified example. FIG. 6 is an enlarged top view showing an example of a rotor in a second modified example. Note that in the following modified examples, parts that are the same as those shown in the previously described drawings are denoted by the same reference numerals, and redundant description will be omitted. Furthermore, the rotor 21 in the first modified example has a second magnet 42, while the rotor 22 in the second modified example has a second magnet 72 formed in a shape approximately similar to the gap 65. The first magnet 49 in the first modified example and the first magnet 71 in the second modified example have shapes that are approximately similar to the holes 58 and 68, respectively.

[0030] The yoke 50 in the first modification includes an outer peripheral portion 51 and side portions 52 and 53 surrounding a hole 58, and an annular portion 36. As shown in FIG. 5, the side portions 52 and 53 of the yoke 50 are bent at intermediate portions between the inner and outer sides in the radial direction.

[0031] 5, the smallest part of the gap is not located opposite the outer peripheral surface 45 of the second magnet 42, but is located near the midpoint between the outer peripheral surface 45 and the inner peripheral surface 46. The width De of the gap 55 in the circumferential direction at the portion facing the outer peripheral surface 45 is greater than the maximum width Wp of the second magnet. Even in this case, the size Dy of the smallest part of the gap is smaller than the size Wp of the second magnet 42 in the circumferential direction near the inner peripheral surface 46, and therefore the second magnet 42 is prevented from protruding radially outward.

[0032] Moreover, yoke 60 in the second modified example includes outer peripheral portion 61 and side portions 62 and 63 surrounding hole 69, and annular portion 36. As shown in Fig. 6, side portions 62 and 63 of yoke 60 are bent in the opposite direction to side portions 52 and 53 shown in Fig. 5 at the intermediate portion between the inner and outer sides in the radial direction.

[0033] 6, the maximum portion of the second magnet is formed near the midpoint between the outer peripheral surface 75 and the inner peripheral surface 76, rather than near the inner peripheral surface 76 of the second magnet 72. Furthermore, the circumferential size Df of the gap 65 at the radially outer side is smaller than the circumferential size Wr of the second magnet 72 near the inner peripheral surface 76. Even in this case, the size Wq of the maximum portion of the second magnet is larger than the smallest portion Df of the gap 65 in the circumferential direction, and therefore the second magnet 72 is prevented from protruding radially outward.

[0034] As shown in each of the above-described modified examples, it is sufficient that the portion of the second magnet that is wider than the minimum gap portion is formed radially inward relative to the minimum gap portion, or that the portion of the gap that is narrower than the maximum gap portion of the second magnet is formed radially outward relative to the maximum gap portion of the second magnet. However, to prevent the second magnet from protruding radially outward and coming into contact with the stator 10, it is desirable that the distance between the minimum gap portion and the portion of the second magnet that is wider than the minimum gap portion, or between the portion of the gap that is narrower than the maximum gap portion of the second magnet and the maximum gap portion of the second magnet, is sufficiently small. Specifically, it is preferable that the radial distance between the minimum gap portion and the portion of the second magnet that is wider than the minimum gap portion, or the distance between the portion of the gap that is narrower than the maximum gap portion of the second magnet and the maximum gap portion of the second magnet, is smaller than the distance D2 between the second magnet and the stator 10 shown in FIG. 3. Furthermore, it is desirable that the width of the side portion in the circumferential direction is constant even when bending, as shown in Figure 5, but the width of the gap in the circumferential direction may be changed by changing the width of the side portion in the circumferential direction.

[0035] The rotor 23 of the third modification may further include a third magnet having a magnetic flux direction different from that of the first magnet and the second magnet. Fig. 7 is an enlarged top view showing an example of a rotor in the third modification. As shown in Fig. 7, the rotor 23 of the third modification includes a second magnet 82 and a third magnet 83 instead of the second magnet 42.

[0036] In the third modified example, the second magnet 82 and the third magnet 83 have substantially the same shape but have different magnetic flux directions. The second magnet 82 and the third magnet 83 are arranged symmetrically and in contact with each other in the circumferential direction.

[0037] 7, in the third modified example as well, the sum of the circumferential width Ws of the second magnet 82 and the circumferential width Wt of the third magnet 83 on the radially inner side is greater than the width Dc on the radially outer side of the gap 35. This prevents the second magnet 82 and the third magnet 83 from protruding radially outward.

[0038] Furthermore, in the embodiment, the configuration has been described in which the shape of the second magnet 42 is substantially the same as the shape of the gap 35, but the embodiment is not limited to this. Fig. 8 is an enlarged top view showing an example of a rotor in a fourth modified example. As shown in Fig. 8, the rotor 24 in the fourth modified example includes a first magnet 91 that has a different shape from the first magnet 41, and a second magnet 92 that has a different shape from the second magnet 42.

[0039] The second magnet 92 is formed so that a portion 96 that faces the annular portion 36 of the yoke 30 in the radial direction has a curved shape. In addition, in the second magnet 92, the slope a3 of the portion that faces the side portion 32 is different from the slope a1 of the side portion 32, and the slope a4 of the portion that faces the side portion 33 is different from the slope of the side portion 33.

[0040] As described above, the second magnet 92 may have a curved shape in its upper surface, and may not be formed substantially parallel to the side portions. The same applies to the first magnet 91, as shown in FIG. 8 . Furthermore, the side portions of the first and second magnets may have a curved shape in their upper surface, and may not be formed substantially parallel to the annular portion of the yoke. Even in this configuration, the circumferential width Wu of the second magnet 92 near the radially inner side is greater than the circumferential width Dc of the second magnet 92 near the radially outer side of the gap 35, and therefore protrusion radially outward is suppressed.

[0041] The rotor or stator described in the embodiment and each modified example of the present invention may be mounted on an actuator, electronic device, etc. Specifically, the rotor or stator described in the embodiment and each modified example of the present invention may be housed in a frame, housing, body, etc. of an actuator or electronic device, and used as a driving element for the actuator or electronic device.

[0042] 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. [Explanation of symbols]

[0043] 1 motor, 10 stator, 11 stator core, 12 insulator, 13 coil, 20, 21, 22, 23, 24 rotor, 30, 50, 60 yoke, 31, 51, 61 outer periphery, 32, 33, 52, 53, 62, 63 side, 34 inner periphery, 35 gap, 36 annular portion, 38 hole, 39 frame, 41, 49, 71, 91 first magnet, 42, 72, 82, 92 second magnet, 83 third magnet

Claims

1. a rotor having a yoke, a plurality of first magnets, and a second magnet; the yoke includes a plurality of frames having an outer periphery; the first magnets are respectively disposed within the frames, The second magnet is located between two adjacent frames among the plurality of frames in the circumferential direction, the second magnet has a portion in a circumferential direction that is larger than the width between the outer peripheries of the two frames, The frame has a portion in a circumferential direction that is wider than the width of the outer circumferential portion of the frame, the portion being located radially inward of the outer circumferential portion. Motor.

2. a stator; an outer circumferential portion of the second magnet faces the stator in the radial direction; An outer periphery of the first magnet faces the stator via the frame. The motor according to claim 1 .

3. the frame includes the outer circumferential portion, an inner circumferential portion, and a side portion connecting the outer circumferential portion and the inner circumferential portion, The motor according to claim 1 or 2, wherein the sides of the frame are inclined relative to the radial direction.

4. the yoke further includes an annular portion that forms an inner periphery of the plurality of frames; the frame sides extend radially from the annular portion; 4. The motor according to claim 1.

5. The motor according to claim 1 , wherein the second magnet comprises an outer circumferential portion and a portion whose size in the circumferential direction is greater than the width in the circumferential direction of the outer circumferential portion.

6. a rotor having a yoke, a plurality of first magnets, a second magnet, and a third magnet; the yoke includes a plurality of frames having an outer periphery; the first magnets are respectively disposed within the frames, the second magnet and the third magnet are disposed adjacent to each other between two adjacent frames among the plurality of frames in the circumferential direction, At any position radially inside the outer circumferential portion, the sum of the circumferential length of the second magnet and the circumferential length of the third magnet is greater than the circumferential distance between the two adjacent frames at the outer circumferential portion. Motor.

Images