Electromagnetic device

Abstract

This electric motor comprises a stator in which an outside magnetic field section and an inside magnetic field section are provided to form a magnetic field, and the outside magnetic field section and the inside magnetic field section are formed into substantially tubular shapes by arranging permanent magnets in a circumferential direction, the permanent magnets having magnetization directions that are changed according to the number n of divisions, the number n of divisions being an integer greater than or equal to 3. Further, tubes made from ferromagnetic materials are arranged between the outside magnetic field section and the inside magnetic field section, and a coil is attached to the tubes. With this structure, the electric motor can cool the coil effectively through the tubes.

Description

Technical Field

[0001] The disclosed technology relates to an electromagnetic device in which an armature coil is disposed between a pair of magnet arrays.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2015-027208 discloses an electromagnetic induction device that uses first and second permanent magnet arrays in which a plurality of permanent magnets are each arranged with the magnetic pole direction changing by integer equal divisions of 2π, and an armature coil is disposed between the first permanent magnet array and the second permanent magnet array. These first and second permanent magnet arrays are called Halbach arrays. In a Halbach array, in a plurality of permanent magnets arranged in one direction, by changing the magnetic pole direction by integer equal divisions of 2π, the magnetic field on one side in the direction intersecting the arrangement direction is weakened and the magnetic field on the other side is strengthened.

[0003] By using a so-called dual Halbach array in which the first permanent magnet array and the second permanent magnet array are opposed with the sides where their magnetic fields are strengthened facing each other, the number of magnetic fluxes linked to the armature coil between the first permanent magnet array and the second permanent magnet array can be increased (made larger), and an electromagnetic induction device with a large output can be obtained.

[0004] Further, by making the arrangement direction of the permanent magnets circular in each of the first permanent magnet array and the second permanent magnet array to form each into a substantially annular (cylindrical) shape, and disposing an armature coil between the inner permanent magnet array and the outer permanent magnet array, a rotating electric machine with a large output can be obtained.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, when applying a dual Halbach array to an electric motor, it is common to use the field magnet on the rotor side and the armature on the stator side. For this reason, in the electric motor, the rotor has a double cylindrical structure in which an inner rotor and an outer rotor are integrated.

[0006] However, heat is generated in the coil. Therefore, in a motor with a double cylinder structure, since the coil is arranged inside the rotor (between the inner rotor and the outer rotor), it is difficult to exhaust the heat of the coil, and heat exhaustion becomes a problem in order to increase the output density.

[0007] In view of the above facts, the present disclosure has been made, and an object thereof is to provide an electromagnetic device capable of improving the output density by enabling effective heat exhaustion of the armature.

Means for Solving the Problem

[0008] The electromagnetic device according to the first aspect for achieving the above object includes a moving body having a first magnet array and a second magnet array, each of which has a plurality of permanent magnets arranged along one direction, with the magnetization direction being sequentially changed by an angle obtained by dividing one electrical angle cycle by a division number n, where n is any one of numbers 3 or more. The first magnet array and the second magnet array are separated by a predetermined gap length and are arranged to face each other in a direction that enhances each other's magnetic fields. The electromagnetic device also includes a support body formed of a ferromagnetic material with a predetermined thickness dimension, and the support body is arranged between the first magnet array and the second magnet array such that the gap length between the support body and the first magnet array is the same as the gap length between the support body and the second magnet array. The electromagnetic device further includes a fixed body relative to which the moving body moves, and three-phase armatures each having a hollow core and each being divided into a first magnet array side and a second magnet array side of the support body and arranged on the support body.

[0009] In the electromagnetic device according to the first aspect, the first magnet array and the second magnet array are arranged on the moving body. The first magnet array and the second magnet array are each a Halbach magnet array in which a plurality of permanent magnets are arranged along one direction (a predetermined direction), with the magnetization direction being sequentially changed by an angle obtained by dividing one electrical angle cycle by a division number n, where n is any one of numbers 3 or more. The first magnet array and the second magnet array are separated by a predetermined gap length and are arranged to face each other in a direction that enhances each other's magnetic fields. Thus, a dual Halbach magnet array is formed on the moving body.

[0010] The fixed body relative to which the moving body moves has a support formed of a ferromagnetic material with a predetermined thickness dimension, and the support is disposed between a first magnet array and a second magnet array. Also, the support is such that the gap length between the support and the first magnet array is the same as the gap length between the support and the second magnet array.

[0011] Also, the support supports three-phase armatures each having a hollow core, and the armatures are each divided into a first magnet array side and a second magnet array side of the support and disposed on the support.

[0012] Here, even if the support is disposed between the first magnet array and the second magnet array, since a ferromagnetic material having a permeability higher than that of air or the like is used for the support, the magnetic field formed by the first magnet array and the second magnet array is not disturbed. Also, the ferromagnetic material is a metal or the like having an extremely high thermal conductivity compared to air, and each of the armatures can be cooled by cooling the support.

[0013] Thereby, even if the armature is disposed between the first magnet array and the second magnet array that move relative to the armature, effective cooling of the armature becomes possible, and it is not necessary to suppress the current value flowing through the armature more than necessary to suppress the heat generation of the armature, so that the output density can be improved.

[0014] In the electromagnetic device of the second aspect, in the first aspect, the division number n is any number obtained by adding 2 to a multiple of 3.

[0015] Also, in the electromagnetic device of the third aspect, in the first or second aspect, the moving body is a rotor in which the permanent magnets are arranged in the circumferential direction with each of the first magnet array and the second magnet array centered on one center point, and the fixed body is a cylindrical stator centered on the center point.

Advantages of the Invention

[0016] According to the electromagnetic device of the present disclosure, even when the armature is disposed between the first magnet array and the second magnet array, it is possible to effectively exhaust the heat generated by the armature using the support, and it is possible to improve the output density.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 7A

Figure 7B

Figure 8A

Figure 8B

Figure 8C

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In this embodiment, a three-phase synchronous motor (hereinafter referred to as motor 10) is applied as an example of an electromagnetic device. In FIG. 1, the main part of the motor 10 is shown in an exploded perspective view, and in FIGS. 2A and 2B, the motor 10 is shown in a schematic cross-sectional view in the axial direction. Note that FIG. 1 is a schematic perspective view seen from an oblique side in the axial direction of the motor 10. Further, FIG. 2A is a schematic cross-sectional view seen from the other side in the axial direction of the motor 10, and FIG. 2B is a schematic cross-sectional view seen from one side in the axial direction of the motor 10.

[0019] As shown in FIGS. 1, 2A, and 2B, the motor 10 includes a rotor 12 as a moving body and a stator 14 as a fixed body, and the rotor 12 and the stator 14 are housed in a casing (housing) not shown.

[0020] A plate 16 is disposed on the rotor 12, and a plate 18 is disposed on the stator 14. The plates 16 and 18 are each in a substantially disk shape with a required diameter, and their center lines are overlapped and opposed to each other. In the following description, a point on the overlapped center line will be described as point P.

[0021] On the rotor 12, a substantially cylindrical outer shell 20 is disposed on the outer peripheral edge of the plate 16. The outer shell 20 has its center line overlapped with point P and is fixed to the surface of the plate 16 on the side of the plate 18. Further, on the plate 16, a field magnet 22 (not shown in FIG. 1) is formed on the inner peripheral side (radially inner side) of the outer shell 20. Furthermore, a shaft 24 as a rotating shaft is disposed on the plate 16. The shaft 24 is disposed through the axial center of the plate 16 and is fixed to be rotatable integrally with the plate 16.

[0022] The plate 18 of the stator 14 has a circular hole 26 formed through the axial center portion, and one end side of the shaft 24 of the rotor 12 is disposed through the circular hole 26 so as to be relatively rotatable. Further, a cylindrical cylinder 28 as a support is disposed on the plate 18, and a ferromagnetic material is used for the cylinder 28. The cylinder 28 is fixed to the plate 16 side of the plate 18 with its center line overlapping the center line of the circular hole 26 (shaft 24).

[0023] The outer peripheral surface and the inner peripheral surface of the cylinder 28 are formed smoothly (without unevenness), and each of the inner peripheral surface and the outer peripheral surface is formed to have a constant radius with respect to the point P. Further, for the cylinder 28, an electromagnetic steel sheet, a metal having no crystal structure (such as amorphous metal), or the like can be used. At this time, the cylinder 28 is preferably structured so that eddy currents do not occur. For example, it may be made thin, or thin materials may be stacked, whereby even when disposed in a magnetic field, disturbance of the magnetic field by eddy currents can be suppressed.

[0024] A plurality of coils (armatures) 30 are disposed in the stator 14, and the coil 30 is an air-core coil using Litz wire having a predetermined cross-sectional area. The coil 30 is divided into a coil 30U for the U phase, a coil 30V for the V phase, and a coil 30W for the W phase in a three-phase AC power supply. The coil 30 is arranged in the circumferential direction of the cylinder 28 with the coils 30U, 30V, and 30W being one set and a plurality of sets of coils 30 being arranged. Note that the arrangement (arrangement order) of the coils 30 (30U, 30V, 30W) of each phase and the relative position with respect to the field magnet 22 (the following permanent magnets 36 and 38) can be an arrangement that enables the motor 10 to be rotationally driven. The number of sets of the coils 30 (30U, 30V, 30W) and the number of sets of the field magnet 22 (the following permanent magnets 36 and 38) are determined according to the combination of the number of magnetic poles and the number of slots of the motor 10 (not shown).

[0025] Each coil 30 (30U, 30V, 30W) is divided into an inner coil 30A and an outer coil 30B. Coils 30U, 30V, 30W of coil 30A are arranged inside the cylindrical body 28, and coils 30U, 30V, 30W of coil 30B are arranged outside the cylindrical body 28. Coils 30U, 30V, 30W are distributed to the inside and outside of the cylindrical body 28 and are grouped together. Coils 30A and 30B are wound such that each of coils 30U, 30V, 30W has a hollow core and the current direction and current value are the same in the same magnetic field. Also, in coils 30A and 30B, coils 30U are connected in series with each other, coils 30V are connected in series with each other, and coils 30W are connected in series with each other.

[0026] In the electric motor 10, the plate 18 of the stator 14 is fixed to the casing, and both axial ends of the shaft 24 protruding from each of the plates 16 and 18 are rotatably attached to the casing via bearings or the like (not shown). Thereby, in the electric motor 10, the field magnet 22 (rotor 12) is relatively rotatable with respect to the stator 14, and the shaft 24 is rotatable.

[0027] Next, the cylindrical body 28 that supports the field magnet 22 and the coil 30 in the electric motor 10 will be described. The field magnet 22 is formed by an outer field magnet portion 32 each having a substantially cylindrical shape (annular shape when viewed in the axial direction) and an inner field magnet portion 34 having an outer diameter smaller than the inner diameter of the outer field magnet portion 32. In the electric motor 10, the outer field magnet portion 32 functions as one of the first magnet array and the second magnet array, and the inner field magnet portion 34 functions as the other of the first magnet array and the second magnet array.

[0028] The field magnet 22 is disposed on the plate 16 such that the center lines of the outer field magnet portion 32 and the inner field magnet portion 34 are overlapped with the center line of the plate 16. A plurality of permanent magnets 36 are arranged in the circumferential direction centered on the center line of the plate 16 in the outer field magnet portion 32, and a plurality of permanent magnets 38 are arranged in the circumferential direction centered on the center line of the plate 16 in the inner field magnet portion 34, forming a substantially cylindrical shape. Thereby, the rotor 12 has a double rotor structure of the outer field magnet portion 32 (outer rotor) and the inner field magnet portion 34 (inner rotor), and the outer field magnet portion 32 and the inner field magnet portion 34 are rotated integrally.

[0029] The cylindrical body 28 in which the coil 30 is disposed is substantially cylindrical as a whole (annular in the axial direction view). The cylindrical body 28 in which the coil 30 is disposed has an inner diameter (the diameter on the inner circumferential side formed by the coil 30A) larger than the outer diameter of the inner field magnet portion 34, and an outer diameter (the diameter on the outer circumferential side formed by the coil 30B) smaller than the inner diameter of the outer field magnet portion 32. Thereby, the stator 14 is inserted and disposed between the outer field magnet portion 32 and the inner field magnet portion 34 of the rotor 12 (field magnet 22) with the cylindrical body 28 and the coil 30 being integrated.

[0030] On the other hand, in the electric motor 10, the Halbach magnet array is applied to each of the arrangements of the permanent magnets 36 in the outer field magnet portion 32 and the permanent magnets 38 in the inner field magnet portion 34.

[0031] FIGS. 6A and 6B schematically show field magnets using a pair of magnet arrays. FIG. 6A shows a field magnet 40, and FIG. 6B shows a field magnet 42 to which a dual Halbach magnet array using a general Halbach magnet array in a pair is applied. FIGS. 7A and 7B schematically show an example of the simulation result of the magnetic flux distribution (magnetic flux density distribution). FIG. 7A shows the magnetic flux distribution in the field magnet 40 of FIG. 6A, and FIG. 7B shows the magnetic flux distribution in the field magnet 42 of FIG. 6B.

[0032] In FIGS. 7A and 7B (the same applies to FIGS. 5A and 5B below), the magnetic flux density of the white part is the lowest, and the color becomes darker as the magnetic flux density increases. Also, in the drawings, the magnetization direction in the permanent magnet is set as the direction from the S pole to the N pole, and the mounting direction is indicated by an arrow. Also, in FIGS. 6B, 7A, and 7B, the illustration of the armature (coil 50 below) is omitted.

[0033] As shown in FIGS. 6B and 7B, for the field magnet 42, a pair of magnet arrays (permanent magnet arrays) 44 are used. In the magnet array 44, an integer (positive number) of 3 or more is used as the division number n, and the angle (divided angle) obtained by dividing one electrical angle cycle (2π = 360°) by the division number n is set as the set angle. In the magnet array 44, when arranging permanent magnets 36 with a rectangular cross-section (it may be a cuboid shape or a cube shape) along one direction, the magnetization direction is changed in order by the set angle each time.

[0034] The division number n may be an integer of 3 or more, but an integer (positive number) obtained by adding 2 to a multiple of 3 among integers (positive numbers) of 3 or more is more preferable. From this, in this embodiment, m = 2 is applied when n = 3·m + 2, and the division number n = 8 (= 3×2 + 2) is set.

[0035] In the magnet array 44, as the permanent magnet 46, permanent magnets 46A to 46H with a set angle of 45° (π / 4) and a magnetization direction shifted by 45° are used, and they are arranged in order along one direction in the order of permanent magnets 46A, 46B, ···, 46H. Thereby, in the magnet array 44, the magnetic field on one side in the direction intersecting with the arrangement direction of the permanent magnet 46 is suppressed (weakened), and the magnetic field on the other side is strengthened compared to the magnetic field on one side, forming a Halbach magnet array. Note that between the two magnet arrays 44, the permanent magnets 46 are arranged in order toward one side in one direction, and the permanent magnets 46 are arranged in order toward the other side in one direction.

[0036] In addition, in the field magnet 42, two magnet arrays 44 are opposed to each other so that the magnetic field between them (in the gap) is strengthened, and the distance dimension between the opposing surfaces (magnetized surfaces) of the two magnet arrays 44 is set as the gap length h. For this reason, in the field magnet 42, the distance between the center line C between the magnet arrays 44 and the magnetized surface (the surface on the center line C side) of each magnet array 44 becomes the same distance h1 (h1 = h / 2).

[0037] As a result, a dual Halbach magnet array is formed in the field magnet 42, and the field magnet 42 can improve the output by further strengthening the magnetic field between the magnet arrays. Also, in the field magnet 42, at the center line C of the gap, the strength of the magnetic field in the electrical angle direction (circumferential direction) changes in a substantially sinusoidal wave shape, thereby achieving torque stabilization (suppression of torque ripple).

[0038] On the other hand, as shown in FIGS. 6A and 7A, in the field magnet 40, the magnet arrays 44 are arranged in pairs, and in the field magnet 40, similar to the field magnet 42, two magnet arrays 44 are opposed to each other so as to strengthen the magnetic field between them. Also, a ferromagnetic member 48 is arranged between the two magnet arrays 44 in the field magnet 40. A ferromagnetic material is used for the ferromagnetic member 48, and the ferromagnetic member 48 is formed in a plate shape with a predetermined thickness (thickness dimension) t. Also, the center in the thickness direction of the ferromagnetic member 48 is overlapped with the center line C between the magnet arrays 44.

[0039] A plurality of coils (armatures) 50 are arranged on this ferromagnetic member 48, and the coil 50 is divided into a coil 50U for the U phase, a coil 50V for the V phase, and a coil 50W for the W phase in a three-phase AC power supply. Each coil 50 (50U, 50V, 50W) is divided into a coil 50A and a coil 50B. The coil 50A is arranged on one surface of the ferromagnetic member 48, and the coil 50B is arranged on the other surface of the ferromagnetic member 48. Further, the coils 50A and 50B are wound so that the current direction and current value are the same in the same magnetic field. Also, the coils 50 (coils 50U, 50V, 50W) are connected in series such that the coils 50U, 50V, 50W on the coil 50A side are connected to the coils 50U, 50V, 50W on the coil 50B side, respectively. Note that the arrangement (arrangement order) of the coils 50 (50U, 50V, 50W) for each phase and the relative position with respect to the permanent magnet 46 may be any required arrangement and relative position. For example, a configuration is applied in which the center position of the coils 50 (50U, 50V, or 50W) of the same phase is overlapped with the center position in the arrangement direction of a set of permanent magnets 46 (46A to 46H) (not shown).

[0040] Here, the mirror image method in the electric field can also be applied (hold) in the magnetic field. At this time, it is assumed that magnetic saturation does not occur in the ferromagnetic member 48 due to the magnetic force of one of the magnet arrays 44. In this case, on the surface of the ferromagnetic member 48 on the side of one of the magnet arrays 44, it seems (appears) that a mirror image (magnetic mirror image) of the one magnet array 44 is generated. The mirror image of the one magnet array 44 reflected on the ferromagnetic member 48 corresponds to the other magnet array 44.

[0041] Further, when magnetic flux concentrated from only one of the magnet arrays 44 is applied to the ferromagnetic member 48, magnetic saturation is likely to occur. In particular, when the thickness t of the ferromagnetic member 48 is thin, magnetic saturation is more likely to occur than when it is thick. When magnetic saturation occurs in the ferromagnetic member 48, the magnetic flux density distribution in the gap is disturbed, resulting in torque ripple and the like.

[0042] In the field magnet 40, two magnet arrays 44 are arranged so as to sandwich a ferromagnetic member 48. The ferromagnetic member 48 has a higher magnetic permeability and a lower magnetic resistance than air or the like. Therefore, inside the ferromagnetic member 48, the magnetic flux generated by one magnet array 44 is canceled out by the magnetic flux generated by the other magnet array 44.

[0043] As a result, in the field magnet 40, it is possible to prevent magnetic saturation from occurring in the ferromagnetic member 48. That is, as shown in FIGS. 7A and 7B, in the field magnet 40, by making the distances between the ferromagnetic member 48 and the magnetization surfaces of the two magnet arrays 44 equal, a magnetic field similar to that of the field magnet 42 can be formed. When the ferromagnetic member 48 is disposed offset to one of the two magnet arrays 44, the magnetic flux inside the ferromagnetic member 48 is not canceled out, and thus the magnetic field between the two magnet arrays 44 is disturbed.

[0044] Here, for the gap length h (h = h1 + h1 = 2×h1) in the field magnet 42, the gap length H in the field magnet 40 is set to H = 2×h1 + t (= h1 + h1 + t = h + t). As a result, in the field magnet 40 in which the ferromagnetic member 48 is disposed between the magnet arrays 44, the same effect as that of the field magnet 42 to which the dual Halbach magnet array is applied can be obtained, and the field magnet 40 has the effect of the dual Halbach magnet array.

[0045] In this way, the field magnet 40 in which the ferromagnetic member 48 is disposed between the two magnet arrays 44 can form a magnetic field similar to that of the field magnet 42 in which the ferromagnetic member 48 is disposed at the center position of the magnet array 44.

[0046] On the other hand, FIGS. 3 and 4 schematically show an example of a magnet array in which permanent magnets are arranged in a substantially cylindrical shape (annular shape in the axial direction view). FIGS. 5A and 5B schematically show an example of the simulation result of the magnetic flux distribution (magnetic flux density distribution), where FIG. 5A corresponds to the magnet array of FIG. 3 and FIG. 5B corresponds to the magnet array of FIG. 4.

[0047] Figures 4 and 5B show the field magnet 60, and magnet arrays (permanent magnet arrays) 62 and 64 are used for the field magnet 60. For the magnet arrays 62 and 64, a number obtained by adding 2 to a multiple of 3 among integers (positive numbers) of 3 or more as the number of divisions n applied in the Halbach magnet array is applied, and the number of divisions n = 8 is applied to the magnet arrays 62 and 64 in the same way as the magnet array 44 of the field magnets 40 and 42.

[0048] In the magnet array 62, permanent magnets 66 (66A to 66H) based on the number of divisions n = 8 are arranged in order in the circumferential direction at a predetermined diameter centered on the point P. Further, in the magnet array 64, permanent magnets 68 (68A to 68H) based on the number of divisions n = 8 are centered on the point P and are arranged in order in the circumferential direction with a diameter smaller than the diameter in the magnet array 62. Thereby, in the field magnet 60, the magnet array 64 is disposed opposite to the inside of the magnet array 62, and the permanent magnets 66 and 68 are opposed to each other so that the magnet arrays 62 and 64 strengthen the magnetic field between each other.

[0049] Further, the magnet arrays 62 and 64 are each a Halbach magnet array, and the field magnet 60 is formed by arranging the magnet arrays 62 and 64 opposite to each other so that the magnetic fields between them are strengthened, and a dual Halbach magnet array is formed by the magnet arrays 62 and 64.

[0050] Here, the field magnet 60 is formed by isovoluminously deforming the field magnet 42 (see FIGS. 6B and 7B) in which the magnet arrays 44 are arranged in parallel. At this time, in the field magnet 42, the two magnet arrays 44 have the same volume. On the other hand, in the field magnet 60, the volume ratio between the outer magnet array 62 and the inner magnet array 64 is deformed so as to be equal to the ratio between the gap (air gap) volume outside the center line C in FIG. 4 and the inner gap volume. Hereinafter, for the sake of simplicity of explanation, the permanent magnet 46 that is the source of the permanent magnets 66 and 68 is a square cross-section (cube) with a side length (length dimension) lm of the volume.

[0051] As shown in FIG. 4, in the isovolume deformation, the cross-sectional area ratio α of the radial cross-section of the permanent magnet 68 of the inner magnet array 64 to the same part before deformation (the radial cross-section of the permanent magnet 46 of the magnet array 44 corresponding to the magnet array 64) i, the cross-sectional area ratio α of the radial cross-section of the permanent magnet 66 of the outer magnet array 62 and the corresponding part before deformation (the radial cross-section of the permanent magnet 46 of the magnet array 44 corresponding to the magnet array 62) o , let S be half of the total area of the radial cross-sections of the permanent magnets 66 and 68 in the magnet arrays 62 and 64 g , let the ratio of the area of the radial cross-section of the gap to the average cross-sectional area in the radial direction of each of the permanent magnet 68 of the inner magnet array 64 and the permanent magnet 66 of the outer magnet array 62 be a, and let the side length when converted to the permanent magnet 46 with a square cross-section before deformation be lm. Then, the relationships from formula (1) to formula (8) below are satisfied. Here, Nm is the number for one full rotation of the division number n on the center line C.

[0052]

Equation

[0053] From here, lm, R o , R i , R g , R h satisfy the relationships from formula (9) to formula (13) below. Here, R o is the outer diameter of the magnet array 62, R g is the inner diameter of the magnet array 62, R c0 is the radius of the center line C, R i is the outer diameter of the magnet array 64, R h is the inner diameter of the magnet array 64.

[0054]

Equation

[0055] Here, in the motor, the main variables can be R c0 , Nm, and a. At this time, a is a value for the maximum magnetic flux linkage number with respect to the total mass of the permanent magnets 66 and 68, and is determined for each motor. Also, when R c0 , Nm, and a are determined, each value of the motor (especially, R h , R i , R coBy using , the motor 10 to which the field magnet 60 is applied can be obtained.

[0056] Generally, in a set of Halbach magnet arrays (dual Halbach magnet arrays), the pole pitch τ is τ = n·lm / 2, where n is the number of divisions and lm is the length of one side of the permanent magnet 46. Also, from the number of divisions Nm in one revolution and the radius R of the gap center (center line C), the pole pitch τ at the center line C (gap center) is obtained as τ = (n·π·R co ) / Nm. By setting the cross-sectional shape of the permanent magnet 46 as a square with a side length of lm, the length of the cross-sectional perimeter per unit area is minimized, and the overall dimensions of the field magnet 42 are suppressed as much as possible. c0 ) / Nm. By setting the cross-sectional shape of the permanent magnet 46 as a square with a side length of lm, the length of the cross-sectional perimeter per unit area is minimized, and the overall dimensions of the field magnet 42 are suppressed as much as possible.

[0057] In the field magnet 42 (field magnet formed by a dual Halbach magnet array), at the center line C (gap center), the gap length h at which the maximum number of linked magnetic fluxes is obtained is in the range of 0.5 to 2.0 times the pole pitch τ (0.5τ ≤ h ≤ 2.0τ), and the gap length in the field magnet 60 set by the above relational expression is also included in the range of 0.5 to 2.0 times the pole pitch τ.

[0058] On the other hand, the field magnet 22 of the motor 10 includes an outer field magnet portion 32 and an inner field magnet portion 34, each of which is cylindrical, and a cylindrical body 28 is disposed between the outer field magnet portion 32 and the inner field magnet portion 34. From this, the field magnet 22 corresponds to FIGS. 3 and 5A.

[0059] That is, as shown in FIGS. 3 and 5A, in the field magnet 22, the permanent magnets 36A to 36H to which the number of divisions n = 8 is applied are arranged in order along the circumferential direction (toward one side in the circumferential direction) at a predetermined radius centered on the point P, and the outer field magnet portion 32 is formed. Also, in the field magnet 22, the permanent magnets 38A to 38H to which the number of divisions n = 8 is applied are centered on the point P and are arranged in order along the circumferential direction (toward the other side in the circumferential direction) at a radius smaller than the radius of the outer field magnet portion 32, and the inner field magnet portion 34 is formed. Also, a cylindrical body 28 made of a ferromagnetic material is disposed between the outer field magnet portion 32 and the inner field magnet portion 34.

[0060] Here, with point P as the center in the field magnet 22, let the outer diameter of the outer field magnet portion 32 be RO, the inner diameter of the outer field magnet portion 32 be RG, the outer diameter of the inner field magnet portion 34 be RI, and the inner diameter of the inner field magnet portion 34 be RH. Also, for the field magnet 22, the radius RC of the center line C is the same as the radius R of the center line C in the field magnet 60. cO Similarly. Further, when the field magnet 22 has the same dual Halbach magnet array as the field magnet 60, it is assumed that the relationship of H = h + t can be obtained between the field magnet 22 and the field magnet 60, similar to the relationship between the field magnet 40 and the field magnet 42.

[0061] Thereby, in the field magnet 22, when RO, RG, RC, RI, and RH respectively satisfy the relationships shown in equations (14) to (18), the field magnet 22 can obtain the same effect as the field magnet 60. Note that the arrangement (arrangement order) of the coils 30 (30U, 30V, 30W) of each phase and the relative positions with respect to the permanent magnets 36 and 38 may be any required arrangement and relative positions. For example, a configuration is applied where the center positions of the coils 30 (30U, 30V, or 30W) of the same phase are overlapped with the center positions in the arrangement direction of a set of permanent magnets 36 (36A to 36H), 38 (38A to 38H) (for example, the center position of the permanent magnet 36E and the center position of the permanent magnet 38E) (not shown in the figure).

[0062]

Equation

[0063] In the motor 10 configured in this way, three-phase coils 30 (30U, 30V, 30W) provided on the stator 14 are arranged between the outer field magnet portion 32 and the inner field magnet portion 34 that form the field magnet 22 in the rotor 12, and the outer field magnet portion 32 and the inner field magnet portion 34 are rotatable as a pair with respect to the coil 30. Thereby, in the motor 10, when three-phase AC power is supplied to the coil 30 (30U, 30V, 30W), the outer field magnet portion 32 and the inner field magnet portion 34 are integrally rotated and the shaft 24 is rotated.

[0064] Here, in the electric motor 10, since the coil 30 is an air-core coil, the inductance of the coil 30 can be reduced, and the counter electromotive force generated in the coil 30 can be suppressed. Therefore, in the electric motor 10, the rated rotational speed can be increased. Moreover, in the electric motor 10, by using the air-core coil for the coil 30, the generation of cogging torque can be prevented.

[0065] Further, in the electric motor 10, a Halbach magnet array is applied to each of the outer field magnet portion 32 and the inner field magnet portion 34 of the field magnet 22, and the field magnet 22 is a dual Halbach magnet array. As a result, in the electric motor 10, it is possible to improve the output density as compared with the case where the field magnet 22 is not applied.

[0066] By the way, generally in an electric motor, heat is generated in the coil (armature) by passing an electric current through the coil. At this time, if the coil has to be cooled only by the air in the gap, a large cooling effect cannot be obtained, so the electric current flowing through the coil has to be suppressed. For this reason, in an electric motor, when the electric current flowing through the coil is low (the current value is small), it is difficult to increase the output and increase the output density.

[0067] Here, in the electric motor 10 of the present disclosure, a cylindrical body 28 is provided on the stator 14, and the coil 30 is attached to the cylindrical body 28. This cylindrical body 28 is made of a ferromagnetic material that is a metal, and the cylindrical body 28 has an extremely high thermal conductivity as compared with the air or resin material in the gap between the outer field magnet portion 32 and the inner field magnet portion 34.

[0068] Therefore, in the electric motor 10, by cooling the cylindrical body 28, the heat exhausted from the coil 30 can be effectively discharged. As a result, in the electric motor 10, the electric current flowing through the coil 30 can be increased to increase the output. Further, the increase in the radial dimension of the electric motor 10 is only by the thickness of the cylindrical body 28, so in the electric motor 10, the output density can be improved (increased).

[0069] For cooling such a cylindrical body 28, various methods can be applied, such as a method of cooling the cylindrical body 28 by cooling the plate 18 of the stator 14, or a method of providing the end portion of the cylindrical body 28 on the side opposite to the coil 30 so as to protrude from the plate 18 and cooling the cylindrical body 28 from the protruding portion from the plate 18. Therefore, in the motor 10, the cylindrical body 28 can be easily cooled. Moreover, in the motor 10, since the temperature rise of the coil 30 can be effectively suppressed via the cylindrical body 28, for example, there is no need to increase the cross-sectional area of the electric wire (Litz wire) used for the coil 30 in order to reduce the heat generation (heat generation amount) with respect to the current.

[0070] On the other hand, when a member other than the hollow coil 30 is arranged between the outer field magnet portion 32 and the inner field magnet portion 34, the magnetic field between the outer field magnet portion 32 and the inner field magnet portion 34 is disturbed, resulting in a decrease in the output density and a cogging torque that causes vibration.

[0071] In contrast, in the motor 10, a ferromagnetic cylindrical body 28 having a constant thickness t is arranged such that the center line of the cylindrical body 28 overlaps with the center line C of the outer field magnet portion 32 and the inner field magnet portion 34, and the gap length between the outer peripheral surface of the cylindrical body 28 and the field magnet surface of the outer field magnet portion 32, and the gap length between the inner peripheral surface of the cylindrical body 28 and the field magnet surface of the inner field magnet portion 34 are made the same.

[0072] As a result, as shown in FIGS. 5A and 5B (see also FIGS. 7A and 7B), since a ferromagnetic material having a high magnetic permeability is used and the thickness t is made constant, even if the cylindrical body 28 is provided, the magnetic field between the outer field magnet portion 32 and the inner field magnet portion 34 is not disturbed.

[0073] In FIGS. 8A to 8C, the change in the magnetic flux density with respect to the electrical angle is shown in a diagram. Note that FIG. 8A shows the change in the magnetic flux density along the center line C in the field magnet 60, FIG. 8B shows the change in the magnetic flux density in the vicinity of the surface (closest) on the outer field magnet portion 32 side of the cylindrical body 28 in the field magnet 22, and FIG. 8C shows the change in the magnetic flux density in the vicinity of the surface (closest) on the inner field magnet portion 34 side of the cylindrical body 28 in the field magnet 22. Also, the positive and negative signs in the magnetic flux density in FIGS. 8A to 8C indicate the direction of the magnetic field.

[0074] As shown in FIG. 8A, in the field magnet 60 to which the dual Halbach magnet array is applied, the magnetic flux density on the center line C changes in a sine wave shape according to the electrical angle. For this reason, the field magnet 60 has the effect of the dual Halbach magnet array that suppresses the generation of torque ripple.

[0075] Further, as shown in FIGS. 8B and 8C, in the field magnet 22, on the surfaces of each of the outer field magnet portion 32 and the inner field magnet portion 34 of the cylindrical body 28, the magnetic flux density changes in a sine wave shape according to the electrical angle, which is the same as the change on the center line C of the field magnet 60. Therefore, even in the field magnet 22 provided with the cylindrical body 28, it has the same effect as the field magnet 60. In the motor 10 provided with the field magnet 22, the output density can be improved, and the occurrence of vibrations and the like due to an increase in torque ripple can be suppressed.

[0076] On the other hand, in the motor 10, the number of divisions for determining the setting angle of the magnetization direction of the permanent magnets 36 and 38 in the outer field magnet portion 32 and the inner field magnet portion 34 is set as an integer obtained by adding 2 to a multiple of 3.

[0077] Generally, in a three-phase synchronous motor (three-phase synchronous motor), among the space harmonic components included in the magnetic flux density per one cycle of the electrical angle, it is known that torque ripple caused by the space harmonic components of the orders that are multiples of 3 (third order, sixth order, ···) does not occur (is suppressed). Further, since the amplitude of the space harmonic component affects the torque ripple and the amplitude of the lower-order space harmonic component among the space harmonic components is larger than the amplitude of the higher-order space harmonic component, in particular, the lower-order space harmonic component affects the torque ripple.

[0078] In the electric motor 10, by bringing the coil 30 close to the magnetizing surfaces of the outer field magnet portion 32 and the inner field magnet portion 34, the number of magnetic flux linkages with the coil 30 can be increased (see FIGS. 5A, 5B, 7A, and 7B). As a result, the output torque of the electric motor 10 can also be increased. However, in the vicinity of the surfaces (magnetizing surfaces) of the outer field magnet portion 32 and the inner field magnet portion 34, the space harmonic components are large, and torque ripple caused by the space harmonic components is likely to occur.

[0079] Here, in the electric motor 10, since the division number n is an integer obtained by adding 2 to a multiple of 3, the space harmonic components in the vicinity of the magnetizing surfaces of each of the outer field magnet portion 32 and the inner field magnet portion 34 can be suppressed, so that torque ripple can be more effectively suppressed.

[0080] Also, in the electric motor 10, the coil 30B is disposed on the outer field magnet portion 32 side of the cylindrical body 28, and the coil 30B is disposed on the inner field magnet portion 34 side of the cylindrical body 28. In the electric motor 10, the coil 30B is distributed to the outer field magnet portion 32 side of the cylindrical body 28, and the coil 30A is distributed to the inner field magnet portion 34 side. In the electric motor 10, either one of the coil 30A or the coil 30B may be disposed on the cylindrical body 28, but by distributing the coils 30A and 30B to both sides of the cylindrical body 28, the magnetic field formed by the outer field magnet portion 32 and the inner field magnet portion 34 can be effectively used.

[0081] Note that in the above-described embodiment, the electric motor 10 has been described as an example. However, the disclosed electromagnetic device may be applied to a generator (three-phase generator), and the electromagnetic device may be a rotating electric machine such as an electric motor or a generator.

[0082] In addition, the disclosed electromagnetic device only needs to have a configuration in which a three-phase armature is disposed between Halbach magnet arrays. The electromagnetic device may be a linear motor or the like including a first magnet array and a second magnet array each formed by arranging a plurality of permanent magnets in a substantially straight line, with the armature disposed between the first magnet array and the second magnet array. Examples of such a linear motor include a cylindrical three-phase linear synchronous motor. The linear motor only needs to have a configuration in which the first magnet array and the second magnet array are paired with respect to the armature and relatively moved with respect to the armature. Overall, the configuration may be such that the armature moves between the first magnet array and the second magnet array.

[0083] The cylindrical three-phase linear synchronous motor to which the present disclosure is applied includes a moving body having a double-cylindrical structure formed by a first magnet array and a second magnet array each formed in a substantially cylindrical shape and disposed on one side in the radial direction of the other, and a three-phase armature (coil) formed in a substantially cylindrical shape and disposed between the first magnet array and the second magnet array, and a fixed body relative to which the moving body is relatively moved. The fixed body has a plurality of sets of three-phase coils each wound in an annular shape arranged in the axial direction. Further, the first and second magnet arrays each have permanent magnets formed in a substantially annular shape arranged in the axial direction, and in the radial cross-section (cross-section including the central axis), the magnetization direction is changed in order by an angle obtained by dividing one electrical angle cycle by the number of divisions n, where n is any one of 3 or more numbers. Thereby, a dual Halbach magnet array is formed in the moving body, and the moving body can be relatively moved along the arrangement direction of the permanent magnets with respect to the fixed body.

[0084] Here, in the three-phase linear synchronous motor, a support body formed in a cylindrical shape using a ferromagnetic material is used, and the armature is attached to and supported by the support body. Further, the support body is arranged such that the central position in the thickness direction overlaps with the central positions of the first magnet array and the second magnet array. Thereby, also in the three-phase linear synchronous motor, while maintaining the effect of the dual Halbach magnet array formed by the first magnet array and the second magnet array, effective heat dissipation of the armature can be achieved through the support body, and the output density can be improved.

[0085] Furthermore, for the two rows of permanent magnets (permanent magnets 46) and the three-phase armature (coils 50) in the field magnet 40 shown in FIG. 6A, a flat linear motor is configured by giving each a required length along the arrangement direction of the permanent magnets. There is no problem in applying the present disclosure to such a flat linear motor.

[0086] As described above, the disclosure includes the following aspects. <1> A moving body having a first magnet array and a second magnet array in which a plurality of permanent magnets are arranged along one direction with the magnetization direction being sequentially changed by an angle obtained by dividing one electrical angle cycle by a division number n, where n is any one of numbers of 3 or more, and the first magnet array and the second magnet array are separated by a predetermined gap length and are arranged to face each other in a direction that enhances each other's magnetic fields, A fixed body having a support formed of a ferromagnetic material with a predetermined thickness dimension, the support being arranged such that the gap length between the support and the first magnet array and the gap length between the support and the second magnet array are the same between the first magnet array and the second magnet array, and the moving body being relatively moved, Three-phase armatures each having a hollow core and each being divided into the first magnet array side and the second magnet array side of the support and arranged on the support, An electromagnetic device comprising.

[0087] <2> The electromagnetic device according to <1>, wherein the division number n is any number obtained by adding 2 to a multiple of 3. <3> The moving body is a rotor in which the permanent magnets are arranged in the circumferential direction around one center point for each of the first magnet array and the second magnet array, The fixed body is the stator of the cylindrical shape centered on the center point <1> or <2> electromagnetic device.

[0088] Also, the disclosure of Japanese Patent Application No. 2022-003866 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described in this specification are hereby incorporated by reference into this specification to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. Each has a first magnet array and a second magnet array in which a plurality of permanent magnets are arranged along one direction with the magnetization direction being sequentially changed by an angle obtained by dividing one electrical angle cycle by a division number n, where the division number n is any one of numbers of 3 or more. The first magnet array and the second magnet array are separated by a predetermined gap length, and the first magnet array and the second magnet array are arranged to face each other in a direction that strengthens each other's magnetic fields, a moving body; It has a support made of a ferromagnetic material and formed with a constant thickness dimension. The support is arranged such that the gap length between the support and the first magnet array and the gap length between the support and the second magnet array are the same between the first magnet array and the second magnet array. A fixed body relative to which the moving body is relatively moved; Each of them has a hollow core, and each is a three-phase armature divided into the first magnet array side and the second magnet array side of the support and arranged on the support; An electromagnetic device comprising:

2. The electromagnetic device according to claim 1, wherein the division number n is any one of numbers obtained by adding 2 to a multiple of 3.

3. The moving body is a rotor in which the permanent magnets are arranged in the circumferential direction around one center point in each of the first magnet array and the second magnet array, The electromagnetic device according to claim 1 or claim 2, wherein the fixed body is a cylindrical stator with the support centered around the center point.

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