Magnetic geared rotating machine, power generation system, and drive system

Abstract

To provide a magnetic geared rotary machine that suppress eddy current loss, a power generation system, and a drive system.SOLUTION: A magnetic geared rotary machine includes: a stator; a rotor including a plurality of rotor magnets; and a magnetic pole piece rotor including a plurality of magnetic pole pieces disposed at a radial position between the stator and the rotor. Each magnetic pole piece has a magnetic pole piece end face facing one side in an axial direction. Each rotor magnet has a rotor magnet end face facing one side. At least part of the magnetic pole piece end face is positioned on the other side in the axial direction with respect to the rotor magnet end face. Alternatively, a finger end face facing one side, included in each of the plurality of fingers sandwiching and holding the stator magnet provided on teeth of the stator from both sides in a circumferential direction, is positioned on the other side with respect to the teeth end face facing one side, of the teeth.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a magnetic gear rotating machine, a power generation system, and a drive system.

Background Art

[0002] Conventionally, a magnetic gear rotating machine that converts the rotational speed between two rotors and transmits torque is known. For example, the magnetic gear rotating machine disclosed in Patent Document 1 includes, in order from the radially inner side, an inner rotor that supports a plurality of permanent magnets, an outer rotor that includes a plurality of magnetic pole pieces, and a stator. The stator is provided with a plurality of windings and a plurality of stator magnets. When the inner rotor rotates due to a rotating magnetic field generated in response to a three-phase alternating current flowing through the windings, the magnetic flux generated by the permanent magnets of the inner rotor is modulated by the magnetic pole pieces. The outer rotor rotates due to the modulated magnetic field and the magnetic field of the stator magnets.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order for a magnetic gear rotating machine to operate efficiently, it is preferable to suppress eddy current losses in, for example, the stator and magnetic pole pieces.

[0005] An object of the present disclosure is to provide a magnetic gear rotating machine, a power generation system, and a drive system in which eddy current losses are suppressed.

Means for Solving the Problems

[0006] The magnetic gear rotating machine according to at least one embodiment of the present invention includes a stator, and a rotor including a plurality of rotor magnets, A magnetic pole piece rotor including a plurality of magnetic pole pieces provided at a radial position between the stator and the rotor, each of the magnetic pole pieces has a magnetic pole piece end face facing one side in the axial direction, each of the rotor magnets has a rotor magnet end face facing the one side, at least a part of the magnetic pole piece end face is located on the other side in the axial direction with respect to the rotor magnet end face, or, at least one of the relationships is established, that is, the finger end face facing the one side of each of the plurality of fingers that sandwich and hold the stator magnet provided on the teeth of the stator from both sides in the circumferential direction is located on the other side with respect to the teeth end face facing the one side of the teeth.

[0007] A power generation system according to at least one embodiment of the present invention includes a prime mover, the above magnetic gear rotating machine as a magnetic gear generator configured to be driven by an input from the prime mover to generate electricity, and is provided.

[0008] A drive system according to at least one embodiment of the present invention includes the above magnetic gear rotating machine as a magnetic gear motor configured to output power, and a drive unit configured to be driven by the power output from the magnetic gear rotating machine. is provided.

Advantages of the Invention

[0009] According to the present disclosure, a magnetic gear rotating machine, a power generation system, and a drive system with reduced eddy current loss can be provided.

Brief Description of the Drawings

[0010]

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0012] (Overview of the magnetic gear-driven rotating machine 10) Figures 1A and 1B are schematic diagrams showing examples of magnetic gear rotating machines. Here, in Figures 1A and 1B, the "axial direction" is the direction parallel to the rotational axis of the pole piece rotors 30 and 40 of the magnetic gear rotating machine 10, and the "radial direction" is the direction perpendicular to the rotational axis of the pole piece rotors 30 and 40. In one embodiment, as shown in Figure 1A, the magnetic gear rotating machine 10 is a magnetic gear generator 10A configured to be driven by an input from the prime mover 2 to generate electricity. The magnetic gear generator 10A is configured to supply the generated electric power P to a power supply destination 4, which may be, for example, a power grid. In other embodiments, as shown in Figure 1B, the magnetic gear rotating machine 10 is a magnetic gear motor 10B configured to receive the supply of electric power P from a power supply source 6, which may be, for example, a power grid, and drive the drive unit 8.

[0013] In the embodiment shown in Figure 1A, the magnetic gear generator 10A forms part of a power generation system 1A. The power generation system 1A may be, for example, a renewable energy power generation system such as a wind power generation system or a tidal power generation system. When the power generation system 1A is a wind power generation system, the prime mover 2 is a windmill rotor. When the power generation system 1A is a tidal power generation system, the prime mover 2 is a waterwheel rotor. The magnetic geared generator 10A includes a stator 20 including a plurality of stator magnets 22 and a plurality of stator windings 24, a pole piece rotor 30 including a plurality of pole pieces 31, and a rotor 40 including a plurality of rotor magnets 42. In the example shown in FIG. 1A, the stator 20 is disposed inside a housing 21 that rotatably supports the pole piece rotor 30 and the rotor 40. The pole piece rotor 30 is configured to rotate together with the rotating shaft 3 of the prime mover 2. Each of the plurality of pole pieces 31 provided at the radial position between the stator 20 and the rotor 40 includes a plurality of electromagnetic steel sheets 35 laminated in the axial direction. The pole piece rotor 30 includes end plates 30A respectively provided at both axial ends of the pole pieces 31, and a power transmission shaft 34 for transmitting power between the prime mover 2. The power transmission shaft 34 of this example is connected to the rotating shaft 3 of the prime mover 2 and is also connected to one end plate 30A. The power transmission shaft 34 is rotatably supported by the housing 21 via a bearing B1. When power is transmitted (input) from the rotating shaft 3 of the prime mover 2 to the power transmission shaft 34, the pole piece rotor 30 rotates integrally with the rotating shaft 3. The rotor 40 includes a rotor core 43 provided with a plurality of rotor magnets 42, end plates 44 respectively provided at both axial ends of the rotor core 43, and a rotating shaft 47 extending axially inside the radial direction of the rotor core 43. The rotating shaft 47 is rotatably supported by the housing 21 via a bearing B2. Note that in the embodiment shown in FIG. 1A, the magnetic geared generator 10A has a configuration in which the stator 20, the pole piece rotor 30, and the rotor 40 are arranged in this order toward the inner side in the radial direction. In another embodiment, the magnetic geared generator 10A has a configuration in which the rotor 40, the pole piece rotor 30, and the stator 20 are arranged in this order toward the inner side in the radial direction.

[0014] The above-described magnetic geared generator 10A integrates a magnetic gear and a generator, and converts mechanical input from the prime mover 2 into electric power by utilizing the harmonic magnetic gear principle and electromagnetic induction. For example, power generation in the magnetic gear generator 10A may be performed according to the following principle. The magnetic flux of the stator magnet 22 is modulated by the magnetic pole pieces 31 of the magnetic pole piece rotor (low-speed rotor) 30 that rotates together with the rotating shaft 3 of the prime mover 2, and the rotor magnet 42 receives magnetic force from the modulated magnetic field and the rotor (high-speed rotor) 40 rotates. At this time, the ratio of the rotational speed of the rotor 40 to that of the magnetic pole piece rotor 30 (speed increase ratio) is represented by the ratio of the number of magnetic poles NL of the magnetic pole pieces 31 to the number of pole pairs NH of the rotor magnet 42 (= NL / NH). When the rotor 40 rotates, a current is generated in the stator winding 24 by electromagnetic induction. Note that the number of magnetic poles NL of the magnetic pole pieces 31 is larger than the number of pole pairs NS of the stator magnet 22. During operation of the magnetic gear generator 10A, various magnetic fluxes such as an NH-order magnetic flux (main magnetic flux) and a harmonic magnetic flux higher than the NH-order (for example, an NH + NS-order magnetic flux) can be generated inside the magnetic gear generator 10A. A part of these magnetic fluxes becomes a leakage magnetic flux Lf that passes through the magnetic pole pieces 31 in the axial direction, for example, to avoid the stator magnet 22. When the leakage magnetic flux Lf is generated, eddy currents can be generated in the in-plane direction in each electromagnetic steel sheet 35. Relatively large eddy currents can be generated in the electromagnetic steel sheets 35 at both axial ends of the magnetic pole pieces 31, for example. Also, during operation of the magnetic gear generator 10A, for example, the magnetic flux Lf 0 generated due to the stator magnet 22 can pass through the stator 20 (more specifically, the teeth 26 described later with reference to FIG. 2) in the axial direction. As a result, eddy currents can be generated at both axial ends of the stator 20. Note that the eddy currents generated in the stator 20 may also be generated when magnetic fluxes generated due to the rotor magnet 42 or magnetic fluxes generated due to energization of the stator winding 24 pass through the stator core 23.

[0015] In the embodiment shown in FIG. 1B, the magnetic gear motor 10B constitutes a part of the drive system 1B. The drive system 1B including the drive unit 8 is driven with the magnetic gear motor 10B as a drive source. As an example, the drive system 1B may be a vehicle that travels with the magnetic gear motor 10B as a power source. In this case, the rotating shaft 9 of the drive unit 8 may be a drive shaft for transmitting power to the wheels. The basic configuration of the magnetic gear motor 10B is common to the magnetic gear generator 10A shown in Fig. 1A. That is, the magnetic gear motor 10B includes a stator 20 including a plurality of stator magnets 22 and a plurality of stator windings 24, a pole piece rotor 30 including a plurality of pole pieces 31, and a rotor 40 including a plurality of rotor magnets 42. In the example shown in Fig. 1B, the stator 20 is fixed inside a housing 21 that rotatably supports the pole piece rotor 30 and the rotor 40. Each of the plurality of pole pieces 31 provided at the radial position between the stator 20 and the rotor 40 includes a plurality of electromagnetic steel sheets 35 laminated in the axial direction. The pole piece rotor 30 includes end plates 30A provided at both axial ends of the pole piece 31, respectively, and a power transmission shaft 34 for transmitting power between the end plates 30A and the drive unit 8. The power transmission shaft 34 of this example is connected to the rotating shaft 9 of the drive unit 8 and is also connected to one of the end plates 30A. The power transmission shaft 34 is rotatably supported by the housing 21 via a bearing B1. The power generated in the magnetic gear motor 10B is transmitted (output) from the power transmission shaft 34 to the rotating shaft 9 of the drive unit 8, so that the shaft 3B rotates and the drive unit 8 operates. The rotor 40 includes a rotor core 43 provided with a plurality of rotor magnets 42, end plates 44 provided at both axial ends of the rotor core 43, respectively, and a rotating shaft 47 extending axially inside the rotor core 43 in the radial direction. The rotating shaft 47 is rotatably supported by the housing 21 via a bearing B2. In the embodiment shown in Fig. 1B, the magnetic gear motor 10B has a configuration in which the stator 20, the pole piece rotor 30, and the rotor 40 are arranged in this order toward the inside in the radial direction. In another embodiment, the magnetic gear motor 10B has a configuration in which the rotor 40, the pole piece rotor 30, and the stator 20 are arranged in this order toward the inside in the radial direction.

[0016] The magnetic geared motor 10B integrates a magnetic gear and a motor, and rotates the rotor (high-speed rotor) 40 by the rotating magnetic field generated by energizing the stator winding 24. The power transmission from the rotor 40 to the pole piece rotor (low-speed rotor) 30 utilizes the principle of the harmonic magnetic gear. The driving unit 8 is driven by transmitting the power output from the operating magnetic geared motor 10B to the rotating shaft 9. During the operation of the magnetic geared motor 10B, similar to the magnetic geared generator 10A, axial leakage magnetic flux Lf may be generated in the pole pieces 31. In this case, eddy currents may be generated in the in-plane direction in each pole piece 31. In the electromagnetic steel sheets 35 at both axial ends of the pole pieces 31, for example, relatively large eddy currents may be generated. Also, during the operation of the magnetic geared motor 10B, for example, the magnetic flux Lf 0 generated due to the stator magnet 22 can pass through the stator 20 (more specifically, the teeth 26 described later) in the axial direction. As a result, eddy currents may be generated at both axial ends of the stator 20. Note that the eddy currents generated in the stator 20 may also be generated when magnetic fluxes such as those generated due to the rotor magnet 42 or the energization of the stator winding 24 pass through the stator 20.

[0017] (Internal Structure of Magnetic Geared Electrical Machine) Subsequently, with reference to FIG. 2, the internal structure of the above-described magnetic geared rotating machine 10 (10A, 10B) will be described. FIG. 2 is a radial cross-sectional view of a magnetic geared rotating machine according to an embodiment. In FIG. 2, for the convenience of viewing the drawing, hatching is applied only to some components of the magnetic geared rotating machine 10. In FIG. 2, the "circumferential direction" is the circumferential direction based on the aforementioned "axial direction" (see FIGS. 1A and 1B).

[0018] As illustrated in FIG. 2, the stator 20 of the magnetic geared rotating machine 10 includes a stator core 23 extending in the circumferential direction, a plurality of teeth 26 protruding from the stator core 23 toward the pole piece rotor 30, and a plurality of stator magnets 22 provided on the tip sides of the plurality of teeth 26. Between every two adjacent ones of the plurality of teeth 26 arranged side by side in the circumferential direction, a plurality of slots 25 extending in the axial direction are provided. Both axial ends of each slot 25 are open, and the above-described stator winding 24 is wound around the slot 25. That is, the plurality of teeth 26 support the stator winding 24. The coil ends of the stator winding 24 that do not fit into the slots 25 may protrude from the stator core 23. Further, the plurality of stator magnets 22 include a plurality of stator magnets 22N, 22S having different poles arranged alternately in the circumferential direction.

[0019] In the example shown in FIG. 2, each stator magnet 22 is an axially long rod-shaped member having a rectangular cross section. FIG. 2 shows a stator 20 having a surface magnet type (SPM; Surface Permanent Magnet) structure in which the stator magnets 22 are attached to the surfaces of the teeth 26. In other embodiments, the stator 20 may have an interior permanent magnet type (IPM; Interior Permanent Magnet) structure in which the stator magnets 22 are embedded in the stator core 23.

[0020] The rotor 40 provided at a position radially displaced from the stator 20 having the above-described configuration includes a plurality of rotor magnets 42 arranged side by side in the circumferential direction. The plurality of rotor magnets 42 are a plurality of permanent magnets having different poles arranged alternately in the circumferential direction. The number of poles of the plurality of rotor magnets 42 is less than the number of poles of the plurality of stator magnets 22. Each rotor magnet 42 may be a long rod member having a rectangular cross section.

[0021] FIG. 2 shows a rotor 40 having a structure of a surface permanent magnet (SPM) type in which a rotor magnet 42 is attached to the surface of a rotor core 43. In other embodiments, the rotor 40 may have a structure of an interior permanent magnet (IPM) type in which the rotor magnet 42 is embedded in the rotor core 43.

[0022] In addition to the rotor magnet 42 and the rotor core 43, the rotor 40 may include the end plates 44 described above with reference to FIGS. 1A and 1B. The end plate 44 is an annular plate extending along the radial direction.

[0023] The pole-piece rotor 30 includes a plurality of pole pieces 31 arranged circumferentially at a radial position between the stator 20 and the rotor 40 having the above-described configuration. Each pole piece 31 includes the plurality of electromagnetic steel sheets 35 (see FIGS. 1A and 1B) laminated in the axial direction. Each pole piece 31 faces the rotor 40 with a first air gap G1 therebetween and faces the stator 20 with a second air gap G2 therebetween. For example, in an embodiment in which both the rotor 40 and the stator 20 have a surface magnet type structure, the pole-piece rotor 30 faces the rotor magnet 42 with the first air gap G1 therebetween and faces the stator magnet 22 with the second air gap G2 therebetween. In another embodiment, the pole-piece rotor 30 may face the stator core 23 and the rotor core 43, respectively. Furthermore, the pole-piece rotor 30 includes a plurality of holders 39 arranged alternately with the plurality of pole pieces 31 in the circumferential direction. Each holder 39 according to one embodiment is formed of a non-magnetic material. In another embodiment, the holder 39 may be formed of a magnetic material. Each pole piece 31 is sandwiched and held by two holders 39 on both circumferential sides. Further, holes 38 (see FIG. 3), which may be circular in the axial direction view, for example, may be formed in the central portions of the plurality of electromagnetic steel sheets 35 constituting the pole piece 31. By inserting a bar (not shown) extending in the axial direction into these holes 38, the plurality of electromagnetic steel sheets 35 may be held. Both axial ends of the above bar may be connected to the pair of end plates 30A (see FIG. 1A) described above, respectively.

[0024] Subsequently, referring to FIG. 3, a more detailed configuration of the stator 20 according to an embodiment is illustrated. FIG. 3 is a schematic diagram of a stator according to an embodiment. The stator 20 may further include a plurality of fingers 29 that sandwich and hold the stator magnets 22 provided at the tips of the teeth 26 from both sides in the circumferential direction. Each finger 29 extending in the axial direction is provided on the surface on the tip side of the tooth 26 and has an integral structure with the tooth 26. The finger 29 may be directly connected to the tooth 26, or at least a part of the finger 29 may be indirectly connected to the tooth 26 via another member such as a holder. In FIG. 3, the length in the circumferential direction at the tip of the tooth 26 (hereinafter also referred to as the tip width of the tooth 26) is indicated by the dimension Lw. Further, the tooth 26 includes a tooth end face 26A facing one side in the axial direction and a tooth opposite face 26B opposite to the tooth end face 26A (see FIG. 4).

[0025] (Positional relationship between the pole piece 32 and the rotor 40 according to the first embodiment) Referring to FIG. 4, the internal structure of the magnetic gear rotating machine 10 will be described in detail. FIG. 4 is a schematic diagram showing the internal configuration of a magnetic gear rotating machine including a pole piece according to the first embodiment.

[0026] The pole piece 32 (31) according to the first embodiment includes a pole piece end face 32A facing one side in the axial direction, and the rotor magnet 42 includes a rotor magnet end face 42A facing one side in the axial direction. In this embodiment, a relationship (hereinafter also referred to as the first positional relationship) is established in which at least a part of the pole piece end face 32A is located on the other side in the axial direction with respect to the rotor magnet end face 42A. Also, a similar positional relationship holds on the other side in the axial direction. Specifically, the pole piece 32 includes a pole piece opposite surface 32B on the side opposite to the pole piece end surface 32A, and the rotor magnet 42 includes a rotor magnet opposite surface 42B on the side opposite to the rotor magnet end surface 42A. And a relationship in which at least a part of the pole piece opposite surface 32B is located on one side in the axial direction with respect to the rotor magnet opposite surface 42B (hereinafter, also referred to as the second positional relationship) holds. Therefore, in the embodiment illustrated in FIG. 4, the pole piece 32 is provided at an axial position between both axial ends of the rotor magnet 42. That is, the pole piece 32 in this example is shorter than the rotor magnet 42 in the axial direction. Also, in the embodiment illustrated in FIG. 4, the plurality of electromagnetic steel sheets 35 constituting the pole piece 32 have the same size as each other. Therefore, only one side surface of the electromagnetic steel sheet 35 located on the outermost one side forms the pole piece end surface 32A, and only one side surface of the electromagnetic steel sheet 35 located on the outermost other side forms the pole piece opposite surface 32B. Note that the pole piece end surface 32A and the pole piece opposite surface 32B may each be formed by one side surface of a plurality of electromagnetic steel sheets 35 (details will be described later with reference to FIG. 5).

[0027] According to the findings of the inventors, by establishing the first positional relationship, the eddy current at one axial end portion of the pole piece 32 is reduced. Similarly, by establishing the second positional relationship, the eddy current at the other axial end portion of the pole piece 32 is reduced. Therefore, according to the above configuration, the magnetic gear-driven rotating machine 10 with reduced eddy current loss can be realized. At least one of the first positional relationship or the second positional relationship may hold even when the third positional relationship described later does not hold. Note that in other embodiments, the second positional relationship may not hold. That is, the pole piece opposite surface 32B may be located at the same axial position as the rotor magnet opposite surface 42B, or may be located on the other side in the axial direction with respect to the rotor magnet opposite surface 42B. Even in this case, by establishing the first positional relationship, the effect of reducing the eddy current loss of the magnetic gear-driven rotating machine 10 can be enjoyed.

[0028] The axial distance (dimension La1) from the end face 32A of the magnetic pole piece to the end face 42A of the rotor magnet will be described in detail. In the present embodiment, the dimension La1 is 0.5% or more and 10% or less of the axial length (dimension Lr) of the rotor magnet 42. The same relationship holds on the other side in the axial direction. Specifically, the axial distance (dimension La2) from the opposite face 32B of the magnetic pole piece to the opposite face 42B of the rotor magnet is 0.5% or more and 10% or less of the axial length of the rotor magnet 42. Note that since FIG. 4 is a schematic diagram, the length relationship and the positional relationship of the components included in the magnetic gear rotating machine 10 are not necessarily faithfully shown. This is the same for the length relationship and the positional relationship described separately later, and the same applies to FIG. 5.

[0029] According to the findings of the inventors, when the axial distance from the end face 32A of the magnetic pole piece to the end face 42A of the rotor magnet is 0.5% or more and 10% or less of the axial length of the rotor magnet 42, the eddy current loss at one axial end of the magnetic pole piece 32 is significantly reduced. Similarly, when the axial distance from the opposite face 32B of the magnetic pole piece to the opposite face 42B of the rotor magnet is 0.5% or more and 10% or less of the axial length of the rotor magnet 42, the eddy current loss at the other axial end of the magnetic pole piece 32 is significantly reduced. Therefore, according to the above configuration, the magnetic gear rotating machine 10 with more effectively reduced eddy current loss is realized. Note that the axial distance (dimension La2) from the opposite face 32B of the magnetic pole piece to the opposite face 42B of the rotor magnet may be less than 0.5% of the axial length (dimension Lr) of the rotor magnet 42, or may exceed 10% of the dimension Lr. Even in this case, by having the above relationship between the dimension La1 and the dimension Lr, the effect of reducing the eddy current loss in the magnetic pole piece 32 can be enjoyed.

[0030] In addition, in the present embodiment, the axial distance (dimension La1) from the end face 32A of the magnetic pole piece to the end face 42A of the rotor magnet is 50% or more and 1200% or less of the facing distance (dimension Ls) between the magnetic pole piece 32 and the rotor 40. The same applies to the other side in the axial direction. Specifically, the axial distance (dimension La2) from the opposite face 32B of the magnetic pole piece to the opposite face 42B of the rotor magnet is 50% or more and 1200% or less of the dimension Ls. In the example of FIG. 4 where the rotor 40 has a surface magnet type structure, the dimension Ls is the radial distance between the magnetic pole piece 32 and the rotor magnet 42. In other examples, the dimension Ls may be the radial distance between the magnetic pole piece 32 and the rotor core 43. Further, the dimension Ls may coincide with the radial dimension of the first air gap G1 described above.

[0031] According to the findings of the inventors, when the axial distance (dimension La1) from the end face 32A of the magnetic pole piece to the end face 42A of the rotor magnet is 50% or more and 1200% or less of the facing distance (dimension Ls) between the magnetic pole piece 32 and the rotor 40, the eddy current loss at one axial end of the magnetic pole piece 32 is significantly reduced. Similarly, when the axial distance (dimension La2) from the opposite face 32B of the magnetic pole piece to the opposite face 42B of the rotor magnet is 50% or more and 1200% or less of the facing distance (dimension Ls) between the magnetic pole piece 32 and the rotor 40, the eddy current loss at the other axial end of the magnetic pole piece 32 is significantly reduced. Therefore, according to the above configuration, the magnetic gear rotating machine 10 with more effectively reduced eddy current loss is realized. The axial distance (dimension La2) from the opposite face 32B of the magnetic pole piece to the opposite face 42B of the rotor magnet may be less than 50% or may exceed 1200% of the facing distance (dimension Ls) between the magnetic pole piece 32 and the rotor 40. Even in this case, by having the relationship between the dimension La1 and the dimension Ls as described above, the effect of reducing the eddy current loss in the magnetic pole piece 32 can be enjoyed.

[0032] (Position relationship between the finger 29 and the tooth 26) In the embodiment illustrated in FIG. 4, the finger 29 includes a finger end face 29A facing one axial side, and the tooth 26 includes a tooth end face 26A facing one axial side. In this example, a relationship in which the finger end face 29A is located on the other axial side relative to the tooth end face 26A (hereinafter, also referred to as a third positional relationship) is established. Also, a similar positional relationship is established on the other axial side. Specifically, the finger 29 includes a finger opposite face 29B on the side opposite to the finger end face 29A, and the tooth 26 includes a tooth opposite face 26B on the side opposite to the tooth end face 26A. And, a relationship in which the finger opposite face 29B is located on one axial side relative to the tooth opposite face 26B (hereinafter, also referred to as a fourth positional relationship) is established.

[0033] According to the findings of the inventors, by establishing the third positional relationship, the eddy current loss at one axial end of the stator 20 is reduced. Similarly, by establishing the fourth positional relationship, the eddy current loss at the other axial end of the stator 20 is reduced. Therefore, according to the above configuration, the magnetic gear rotating machine 10 with reduced eddy current loss can be realized. At least one of the third positional relationship or the fourth positional relationship may be established together with the above-described first positional relationship, or may be established even when the first positional relationship is not established. In addition, in other embodiments, the fourth positional relationship may not be established. That is, the finger opposite face 29B may be located at the same axial position as the tooth opposite face 26B, or may be located on the other axial side relative to the tooth opposite face 26B. Even in this case, by establishing the third positional relationship, the effect of reducing the eddy current loss of the magnetic gear rotating machine 10 can be enjoyed.

[0034] The details of the axial distance (dimension Lt1) from the finger end face 29A to the tooth end face 26A will be described. In this embodiment, the dimension Lt1 is 0.5% or more and 4% or less of the axial length (dimension Le) of the tooth 26. A similar relationship holds on the other side in the axial direction. Specifically, the axial distance (dimension Lt2) from the finger opposite surface 29B to the tooth opposite surface 26B is 0.5% or more and 4% or less of the axial length of the teeth 26.

[0035] According to the inventors' findings, when the axial distance from the finger end surface 29A to the tooth end surface 26A is 0.5% or more and 4% or less of the axial length of the teeth 26, the eddy current loss at one axial end of the stator 20 is significantly reduced. Similarly, when the axial distance from the finger opposite surface 29B to the tooth opposite surface 26B is 0.5% or more and 4% or less of the axial length of the teeth 26, the eddy current loss at the other axial end of the stator 20 is significantly reduced. Therefore, according to the above configuration, the magnetic gear rotating machine 10 with more effectively reduced eddy current loss is realized. Note that the axial distance (dimension Lt2) from the finger opposite surface 29B to the tooth opposite surface 26B may be less than 0.5% of the axial length (dimension Le) of the teeth 26, or may exceed 4% of the dimension Le. Even in this case, by having the relationship between the dimension Lt1 and the dimension Le as described above, the effect of reducing the eddy current loss in the stator 20 can be enjoyed.

[0036] Also, in the embodiment illustrated in FIG. 4, the axial distance (dimension Lt1) from the finger end surface 29A to the tooth end surface 26A is 3% or more and 25% or less of the tip width of the teeth 26 (dimension Lw in FIG. 3). Also, the axial distance (dimension Lt2) from the finger opposite surface 29B to the tooth opposite surface 26B is also 3% or more and 25% or less of the tip width of the teeth 26.

[0037] According to the inventors' findings, when the axial distance from the finger end face 29A to the tooth end face 26A is 3% or more and 25% or less of the tip width of the tooth 26, the eddy current loss at one axial end of the stator 20 is significantly reduced. Similarly, when the axial distance from the finger opposite face 29B to the tooth opposite face 26B is 3% or more and 25% or less of the tip width of the tooth 26, the eddy current loss at the other axial end of the stator 20 is significantly reduced. Therefore, according to the above configuration, the magnetic gear rotating machine 10 with more effectively reduced eddy current loss is realized. In other embodiments, the axial distance (dimension Lt2) from the finger opposite face 29B to the tooth opposite face 26B may be less than 3% of the tip width (dimension Lw in FIG. 3) of the tooth 26, or may exceed 25% of the dimension Lw. Even in this case, by having the relationship between the dimension Lt1 and the dimension Lw as described above, the effect of reducing the eddy current loss in the stator 20 can be enjoyed.

[0038] (Positional relationship among the stator magnet 22, the rotor magnet 42, and the pole piece 32) In the embodiment illustrated in FIG. 4, the stator magnet 22 has a stator magnet end face 22A facing one side in the axial direction and a stator magnet opposite face 22B opposite to the stator magnet end face 22A. The stator magnet end face 22A is located on the other side in the axial direction than the rotor magnet end face 42A. Also, the stator magnet opposite face 22B is located on one side in the axial direction than the rotor magnet opposite face 42B. Therefore, the stator magnet 22 is shorter than the rotor magnet 42 in the axial direction. In FIG. 4, for the convenience of viewing the drawing, the stator magnet 22 having a shorter radial length than the finger 29 is schematically illustrated, but the stator magnet 22 may have the same radial length as the finger 29, or may be longer in the radial direction than the finger 29.

[0039] According to the inventors' findings, by positioning the end face 22A of the stator magnet on the other side in the axial direction than the end face 42A of the rotor magnet, the eddy current loss on one side in the axial direction of the magnetic pole piece 32 can be reduced. Also, the axial length of the stator magnet 22 can be reduced. Further, by positioning the opposite face 22B of the stator magnet on one side in the axial direction than the opposite face 42B of the rotor magnet, the eddy current loss on the other side in the axial direction of each of the magnetic pole piece 32 and the stator 20 can be reduced, and the axial length of the stator 20 can be reduced. Therefore, according to the above configuration, it is possible to realize the magnetic gear rotating machine 10 that achieves both reduction of eddy current loss and cost reduction. Note that the opposite face 22B of the stator magnet may be located at the same axial position as the opposite face 42B of the rotor magnet, or on the other side in the axial direction than the opposite face 42B of the rotor magnet. Even in this case, since the end face 22A of the stator magnet is located on the other side in the axial direction than the end face 42A of the rotor magnet, it is possible to reduce the eddy current loss and reduce the cost of the magnetic gear rotating machine 10.

[0040] In the embodiment illustrated in FIG. 4, the end face 22A of the stator magnet is provided at the same axial position as the end face 32A of the magnetic pole piece, or at an axial position between the end face 32A of the magnetic pole piece and the end face 42A of the rotor magnet. Similarly, on the other side in the axial direction, the opposite face 22B of the stator magnet is provided at the same axial position as the opposite face 32B of the magnetic pole piece, or at an axial position between the opposite face 32B of the magnetic pole piece and the opposite face 42B of the rotor magnet.

[0041] According to the inventors' findings, the portion of the stator magnet 22 on one side than the end face 32A of the magnetic pole piece hardly contributes to the generation of the magnetic transmission torque in the magnetic gear rotating machine 10. Therefore, according to the above configuration, the extra stator magnet 22 can be reduced, and the cost of the magnetic gear rotating machine 10 can be reduced. Note that the opposite face 22B of the stator magnet may be located on the other side in the axial direction than the opposite face 32B of the magnetic pole piece. Even in this case, if the positional relationship between the end face 22A of the stator magnet and the end face 32A of the magnetic pole piece is as described above, the cost reduction of the magnetic gear rotating machine 10 can be achieved.

[0042] (Positional relationship between the magnetic pole piece 33 and the rotor 40 according to the second embodiment) FIG. 5 is a schematic diagram showing the internal configuration of a magnetic gear rotating machine including a magnetic pole piece according to a second embodiment. The magnetic pole piece 33(31) according to the second embodiment has a first magnetic pole piece end portion 331 which is an end portion on one side in the axial direction, and a second magnetic pole piece end portion 332 which is on the side opposite to the first magnetic pole piece end portion 331. On the first magnetic pole piece end portion 331, a magnetic pole piece end face 33A which is an end face of the magnetic pole piece 33 facing one side in the axial direction is formed, and on the second magnetic pole piece end portion 332, a magnetic pole piece opposite face 33B which is an end face opposite to the magnetic pole piece end face 33A is formed.

[0043] And in each of the first magnetic pole piece end portion 331 and the second magnetic pole piece end portion 332, the plurality of electromagnetic steel sheets 35 constituting the magnetic pole piece 33 include a first electromagnetic steel sheet 35A, a second electromagnetic steel sheet 35B, and a third electromagnetic steel sheet 35C in order from the axial center side of the magnetic pole piece 33. The radial length of these electromagnetic steel sheets 35 is shorter for the electromagnetic steel sheets 35 located on the outer side in the axial direction. Also, the end portions 355A, 355B, 355C on the stator 20 side of each of the first electromagnetic steel sheet 35A, the second electromagnetic steel sheet 35B, and the third electromagnetic steel sheet 35C have the same radial position. That is, these electromagnetic steel sheets 35 are laminated so that the radial positions of the end portions on the stator 20 side are aligned. In the above-mentioned first magnetic pole piece end portion 331, one side of each of the first electromagnetic steel sheet 35A, the second electromagnetic steel sheet 35B, and the third electromagnetic steel sheet 35C forms the magnetic pole piece end face 33A. Similarly, in the second magnetic pole piece end portion 332, one side of each of the first electromagnetic steel sheet 35A, the second electromagnetic steel sheet 35B, and the third electromagnetic steel sheet 35C forms the magnetic pole piece opposite face 33B. Among the holes 38 (see FIG. 3) formed in the electromagnetic steel sheet 35, the holes 38 formed in the first electromagnetic steel sheet 35A are circular in the axial view. On the other hand, the holes 38 formed in each of the second electromagnetic steel sheet 35B and the third electromagnetic steel sheet 35C are semi-circular. For example, the holes 38 formed in the third electromagnetic steel sheet 35C preferably surround more than half of the peripheral surface of a bar (not shown) in the axial view. Thereby, a configuration in which the third electromagnetic steel sheet 35C is difficult to come off radially outward with respect to the bar is realized.

[0044] At the end portion 331 of the first magnetic pole piece, the magnetic pole piece end face 33A formed by one side of the third electromagnetic steel sheet 35C is in the same axial position as the rotor magnet end face 42A, but the above-described first positional relationship holds. This is because the magnetic pole piece end face 33A formed by one side of each of the first electromagnetic steel sheet 35A and the second electromagnetic steel sheet 35B is located on the other axial side with respect to the rotor magnet end face 42A. Similarly, also at the second magnetic pole piece end portion 332, since one side of each of the first electromagnetic steel sheet 35A and the second electromagnetic steel sheet 35B that forms the opposite magnetic pole piece face 33B is located on one axial side with respect to the opposite rotor magnet face 42B, the second positional relationship holds. According to the findings of the inventors, even when the first positional relationship in which only a part of the magnetic pole piece end face 33A is located on the other axial side with respect to the rotor magnet end face 42A holds, the eddy current loss at one axial end of the magnetic pole piece 33 is reduced. Similarly, even when the second positional relationship in which only a part of the opposite magnetic pole piece face 33B is located on one axial side with respect to the opposite rotor magnet face 42B holds, the eddy current loss at the other axial end of the magnetic pole piece 33 is reduced. Therefore, the eddy current loss of the magnetic gear rotating machine 10 can be reduced.

[0045] In the embodiment illustrated in FIG. 5, the axial distance between the magnetic pole piece end face 33A and the rotor magnet end face 42A is the axial distance between the end portion of the magnetic pole piece end face 33A on the rotor 40 side (that is, the magnetic pole piece end face 33A formed by the first electromagnetic steel sheet 35A) and the rotor magnet end face 42A, and corresponds to the dimension Lb1 in FIG. 5. For example, if the dimension Lb1 is 0.5% or more of the axial length of the rotor magnet 42 and 10% or less of the axial length of the rotor magnet 42, a remarkable reduction effect of the eddy current loss on one axial side of the magnetic pole piece 33 can be enjoyed. Further, if the dimension Lb1 is 50% or more and 1200% or less of the facing distance between the magnetic pole piece 33 and the rotor 40 (rotor magnet 42 in FIG. 5), a remarkable reduction effect of the eddy current loss on one axial side of the magnetic pole piece 33 can be enjoyed.

[0046] In the embodiment illustrated in FIG. 5, the magnetic pole piece 33 has a stator-side facing surface 36 facing the stator 20 (stator magnet 22 in the example of FIG. 5) and a rotor-side facing surface 37 facing the rotor 40 (rotor magnet 42 in the example of FIG. 5). Both the stator-side facing surface 36 and the rotor-side facing surface 37 extend in the axial direction. In the example of FIG. 5, the end portions 355A, 355B, and 355C of each of the first electromagnetic steel plate 35A, the second electromagnetic steel plate 35B, and the third electromagnetic steel plate 35C constitute a part of the stator-side facing surface 36. On the other hand, only the end portion of the first electromagnetic steel plate 35A on the rotor 40 side among these electromagnetic steel plates 35 constitutes a part of the rotor-side facing surface 37, and the second electromagnetic steel plate 35B and the third electromagnetic steel plate 35C are provided at a radial position closer to the stator 20 than the rotor-side facing surface 37. Therefore, the stator-side facing surface 36 is longer in the axial direction than the rotor-side facing surface 37.

[0047] The magnetic transmission torque during the operation of the magnetic gear rotating machine 10 (more specifically, the magnetic torque transmitted between the magnetic pole piece rotor 30 and the rotor 40) tends to increase as the axial length of the stator-side facing surface 36 becomes longer. According to the above configuration, since the stator-side facing surface 36 is longer than the rotor-side facing surface 37, at least a part of the magnetic pole piece end surface 32A can be positioned on the other axial side of the rotor magnet end surface 42A while ensuring the axial length of the stator-side facing surface 36. Therefore, a magnetic gear rotating machine 10 that can reduce eddy current loss and ensure magnetic transmission torque is realized. In addition, the configuration in which the stator-side facing surface 36 is longer in the axial direction than the rotor-side facing surface 37 can be realized by a simple configuration in which the first electromagnetic steel plate 35A, the second electromagnetic steel plate 35B, and the third electromagnetic steel plate 35C having different radial lengths are laminated. Therefore, by a simple configuration in which a plurality of electromagnetic steel plates 35 having different radial lengths are laminated, it is possible to achieve both reduction of eddy current loss and ensuring of magnetic transmission torque in the magnetic gear rotating machine 10.

[0048] In the embodiment of FIG. 5, the end face 22A of the stator magnet is provided at the same axial position as the end 366A on one axial side of the stator-side facing surface 36, or at an axial position between the end 366A of the stator-side facing surface 36 and the end 377A on one side of the rotor-side facing surface 37. Further, the opposite face 22B of the stator magnet is provided at the same position as the end 366B on the other axial side of the stator-side facing surface 36, or at an axial position between the end 366B of the stator-side facing surface 36 and the end 377B on the other side of the rotor-side facing surface 37. As described above, the portion of the stator magnet 22 located axially outside the pole piece 33 hardly contributes to the generation of the magnetic transmission torque of the magnetic gear rotating machine 10. According to the above configuration, the portion of the stator magnet 22 that hardly contributes to the magnetic transmission torque can be reduced, so that the cost reduction of the magnetic gear rotating machine 10 can be realized. Note that the opposite face 22B of the stator magnet may be located on the other axial side of the end 366B of the stator-side facing surface 36. Even in this case, for example, if the end face 22A of the stator magnet is at the same axial position as the end 366A of the stator-side facing surface 36, the cost reduction of the magnetic gear rotating machine 10 can be realized.

[0049] (Example 1) With reference to FIGS. 6 and 7, the relationship between the axial positional relationship of the components of the magnetic gear rotating machine 10 and the effect of reducing eddy current loss will be described. FIG. 6 shows various magnetic gear rotating machines prepared to verify the effect of reducing eddy current loss. FIG. 7 shows the eddy current loss when the axial positions of the components of the magnetic gear rotating machine are changed.

[0050] The inventors specified by simulation the effect of reducing eddy current loss by changing the axial positions of the components for the magnetic gear rotating machine 10 including the pole piece 32 according to the first embodiment. More specifically, the axial positions of the components shown in the following (A) to (D) were changed, and the eddy current loss obtained by analysis was compared. (A) Pole piece end face 32A (B) Stator magnet end face 22A (C) Finger end face 29A (D) Tooth end face 26A

[0051] More detailed analysis conditions will be described. Based on the magnetic gear rotating machine 10 with the axial positions of (A) to (D) above aligned (No. 1), magnetic gear rotating machines 10 in which any of the components are displaced to the other side in the axial direction (the axial length of the component is shortened) are assumed as Nos. 2 to No. 6. For example, as shown in FIGS. 6 and 7, in the magnetic gear rotating machine 10 of No. 2, the end face 32A of the pole piece is displaced to the other side in the axial direction from the reference. Also, in the magnetic gear rotating machine 10 of No. 3, the end face 32A of the pole piece and the end face 22A of the stator magnet are displaced to the other side in the axial direction from the reference. And the results of specifying the eddy current loss when each of the magnetic gear rotating machines 10 of Nos. 1 to No. 6 functions as the magnetic gear generator 10A by simulation are shown in the upper graph of FIG. 7. The eddy current loss shown in the graph is the sum of the eddy current loss on one side in the axial direction of the pole piece 32 and the eddy current loss on one side in the axial direction of the stator 20. Note that "PP" in the table at the lower part of FIG. 7 is an abbreviation of "Pole Piece" and indicates the end face 32A of the pole piece. "HSR Mag" is an abbreviation of "High Speed Rotor Magnet" and indicates the end face 42A of the rotor magnet (in this analysis, the axial position of the end face 42A of the rotor magnet is not changed). "ST Mag" is an abbreviation of "Stator Magnet" and indicates the end face 22A of the stator magnet. "ST Finger" is an abbreviation of "Stator Finger" and indicates the end face 29A of the finger. "ST Teeth" is an abbreviation of "Stator Teeth" and indicates the end face 26A of the teeth. The amount by which the components shown in Nos. 2 to No. 6 are displaced to the other side in the axial direction with respect to the reference is the same value (constant value).

[0052] By comparing No.1 and No.2 in Fig. 7, it is understood that if the end face 32A of the magnetic pole piece is located on the other side in the axial direction than the end face 42A of the rotor magnet, the eddy current loss (especially the eddy current loss in the magnetic pole piece 32) decreases. That is, when the first positional relationship is established, it is understood that the eddy current loss of the magnetic gear rotating machine 10 decreases. And regardless of whether the above-described components (B) to (D) are displaced to the other side in the axial direction, if the first positional relationship is established, it is understood by comparing No.1 with No.3, No.5, and No.6 that the eddy current loss (especially the eddy current loss in the magnetic pole piece 32) decreases. According to the findings of the inventors, the reason for the decrease in the eddy current loss of the magnetic pole piece 32 is as follows. The leakage magnetic flux Lf generated in the magnetic pole piece 32 passes through the magnetic pole piece 32 in the axial direction and flows to one side in the axial direction from the end face 42A of the rotor magnet (No.1 in Fig. 6). In this regard, since the end face 32A of the magnetic pole piece is located on the other side in the axial direction than the end face 42A of the rotor magnet, as a result, it becomes difficult for the magnetic flux to flow from the end face 32A of the magnetic pole piece to one side in the axial direction from the end face 42A of the rotor magnet, so the leakage magnetic flux Lf generated in the magnetic pole piece 32 is suppressed, and the eddy current loss of the magnetic pole piece 32 decreases. Based on the above reasons, it can be concluded that even when the second positional relationship is established, the eddy current loss at the other end in the axial direction of the magnetic pole piece 32 decreases. Also, it can be concluded that even if a configuration is adopted in which the stator-side facing surface 36 of the magnetic pole piece 32 is longer than the rotor-side facing surface 37, the effect of reducing the eddy current loss can be enjoyed due to the establishment of the first positional relationship. Furthermore, it can be concluded that even when the magnetic gear rotating machine 10 functions as the magnetic gear motor 10B, the same eddy current loss effect can be enjoyed.

[0053] Also, by comparing No.1 and No.4 in Fig. 7, it is understood that if the finger end face 29A is located on the other axial side with respect to the tooth end face 26A, the eddy current loss (especially the eddy current loss in the stator 20) will decrease. That is, when the third positional relationship is established, it is understood that the eddy current loss of the magnetic gear rotating machine 10 will decrease. And even if the above-mentioned components (A) and (C) are displaced to the other axial side, if the third positional relationship is established, it is understood by comparing No.1 and No.5 that the eddy current loss (especially the eddy current loss in the pole piece 32) will decrease. According to the findings of the inventors, the reason for the reduction of the eddy current loss of the teeth 26 is as follows. One of the causes of the eddy current loss in the stator 20 is that the magnetic flux flowing along the axial direction between the fingers 29 flows into the teeth 26 from one axial side (No.1 in Fig. 6). The above magnetic flux flowing between the fingers 29 includes at least one of the magnetic flux Lf 0 (No.1 in Fig. 6), the magnetic flux caused by the rotor magnet 42, or the magnetic flux caused by the energization of the stator winding 24. In this regard, when the finger end face 29A is located on the other axial side than the tooth end face 26A, the above magnetic flux flowing between the fingers 29 can flow in various directions on one axial side rather than the tooth end face 26A. As a result, the magnetic flux flowing into the tooth end face 26A from one axial side is suppressed, and the eddy current flowing through the teeth 26 decreases. Thereby, at least the eddy current loss in the teeth 26 among the eddy current losses in the stator 20 decreases. Based on the above reasons, it can be concluded that when the finger opposite face 29B is located on one axial side than the tooth opposite face 26B (when the fourth positional relationship is established), the effect of reducing the eddy current loss can be enjoyed. Furthermore, it can be concluded that even when the magnetic gear rotating machine 10 functions as the magnetic gear motor 10B, the same eddy current loss effect can be enjoyed.

[0054] Also, by comparing No.1 in Fig. 7 with No.3, No.5, and No.6, it was found that when the end face 22A of the stator magnet is located on the other side in the axial direction than the end face 42A of the rotor magnet, the eddy current loss in the pole piece 32 is reduced. Furthermore, according to the above analysis results, it was found that the magnetic gear rotating machine 10 shown by No.5, in which the end face 32A of the pole piece, the finger end face 29A, and the end face 22A of the stator magnet are displaced to the other side in the axial direction with respect to the end face 42A of the rotor magnet and the tooth end face 26A, exhibits the highest reduction effect of eddy current loss. Also, it was found that the magnetic gear rotating machine 10 shown by No.6, in which the end face 32A of the pole piece, the end face 22A of the stator magnet, the finger end face 29A, and the tooth end face 26A are displaced to the other side in the axial direction than the end face 42A of the rotor magnet, also exhibits a high reduction effect of eddy current loss.

[0055] (Example 2) With reference to Figs. 8 and 9, the reduction effect of the eddy current loss in the pole piece 31 according to the axial distance between the end face 32A of the pole piece and the end face 42A of the rotor magnet will be described. Fig. 8 is a first graph showing the eddy current loss according to the axial distance between the end face of the pole piece and the end face of the rotor magnet. Fig. 9 is a second graph showing the eddy current loss according to the axial distance between the end face of the pole piece and the end face of the rotor magnet.

[0056] The inventors specified the relationship between the dimension La1 of the magnetic gear rotating machine 10 shown by No.2 in Fig. 6 and the eddy current loss in the pole piece 32 shown by No.2 by simulation. The horizontal axis of the graph in Fig. 8 indicates the ratio of dimension La1 to the axial length of the rotor magnet 42 (dimension Lr in Fig. 4). The vertical axis of the same graph indicates the ratio of the eddy current loss in the pole piece 32 shown as No. 2 to the eddy current loss in the pole piece 32 shown as No. 1 in Fig. 7 (the same applies to the vertical axis in Fig. 9). That is, the smaller the value on the vertical axis, the higher the reduction effect of the eddy current loss in the pole piece 32 is exerted. The horizontal axis of the graph in Fig. 9 indicates the ratio of dimension La1 to the opposing distance between the pole piece 31 and the rotor 40 (dimension Ls in Fig. 6). In this analysis, the axial length of the pole piece 32 is changed by the amount of change in dimension La1. Also, the plotted points in the graphs of Figs. 8 and 9 are the eddy current losses obtained by simulation (the same applies to the graphs in Figs. 10 and 11 described later).

[0057] As shown in the graph of Fig. 8, when the ratio of dimension La1 to the axial length of the rotor magnet 42 is 0.5% or more, the eddy current loss becomes approximately 80% or less, and a remarkable reduction effect of the eddy current loss is confirmed. Also, it was found that even when the above ratio exceeds 10%, the reduction effect of the eddy current loss does not improve. Therefore, it was found that when the ratio of dimension La1 to the axial length of the rotor magnet 42 is 0.5% or more and 10% or less, a remarkable reduction effect of the eddy current loss is exerted.

[0058] Next, as shown in the graph of Fig. 9, when the ratio of dimension La1 to the opposing distance between the pole piece 31 and the rotor 40 is 50% or more, the eddy current loss becomes approximately 80% or less, and a remarkable reduction effect of the eddy current loss is confirmed. Also, it was found that even when the above ratio exceeds 1200%, the reduction effect of the eddy current loss does not improve. Therefore, it was found that when the ratio of dimension La1 to the opposing distance between the pole piece 31 and the rotor 40 is 50% or more and 1200% or less, a remarkable reduction effect of the eddy current loss is exerted.

[0059] (Example 3) Referring to FIGS. 10 and 11, the reduction effect of the eddy current loss of the teeth 26 according to the axial distance from the finger end face 29A to the tooth end face 26A will be described. FIG. 10 is a first graph showing the eddy current loss according to the axial distance from the finger end face to the tooth end face. FIG. 11 is a second graph showing the eddy current loss according to the axial distance from the finger end face to the tooth end face.

[0060] The inventors specified the relationship between the dimension Lt1 of the magnetic gear rotating machine 10 shown in No. 4 of FIG. 6 and the eddy current loss in the stator 20 shown in No. 4 by simulation. The horizontal axis of the graph in FIG. 10 shows the ratio of the dimension Lt1 to the axial length (dimension Le in FIG. 4) of the teeth 26. The vertical axis of the graph shows the ratio of the eddy current loss in the stator 20 shown in No. 4 to the eddy current loss in the stator 20 shown in No. 1 of FIG. 6 (the same applies to the vertical axis of FIG. 11). That is, the smaller the value on the vertical axis, the higher the reduction effect of the eddy current loss in the stator 20 is exerted. The horizontal axis of the graph in FIG. 11 shows the ratio of the dimension Lw to the opposing distance (dimension Ls in FIG. 6) between the pole piece 31 and the rotor 40. In this analysis, the axial length of the finger 29 is changed by the amount of change in the dimension Lt.

[0061] As shown in the graph of FIG. 10, when the ratio of the dimension Lt1 to the axial length of the teeth 26 is 0.5% or more, the eddy current loss becomes 90% or less, and a remarkable reduction effect of the eddy current loss is confirmed. It was also found that even when the above ratio exceeds 4%, the reduction effect of the eddy current loss does not improve. Therefore, it was found that when the ratio of the dimension Lt1 to the axial length of the teeth 26 is 0.5% or more and 4% or less, a remarkable reduction effect of the eddy current loss in the stator 20 is exerted.

[0062] Next, as shown in the graph of FIG. 11, when the ratio of the dimension Lw to the facing distance between the pole piece 32 and the rotor 40 becomes 3% or more, the eddy current loss becomes 90% or less, and a remarkable reduction effect of the eddy current loss was confirmed. Also, it was found that even when the above ratio exceeds 25%, the reduction effect of the eddy current loss does not improve. Therefore, it was found that when the ratio of the dimension Lw to the facing distance between the pole piece 31 and the rotor 40 is 3% or more and 25% or less, a remarkable reduction effect of the eddy current loss in the stator 20 is exhibited.

[0063] (Summary) Hereinafter, an overview of the magnetic gear rotating machine 10, the power generation system 1A, and the drive system 1B according to several embodiments will be described.

[0064] 1) The magnetic gear rotating machine (10) according to at least one embodiment of the present disclosure is a stator (20), a rotor (40) including a plurality of rotor magnets (42), and a pole piece rotor (30) including a plurality of pole pieces (31) provided at a radial position between the stator (20) and the rotor (40). Each of the pole pieces (31) has a pole piece end face (32A, 33A) facing one side in the axial direction. Each of the rotor magnets (42) has a rotor magnet end face (42A) facing the one side. At least a part of the pole piece end faces (32A, 33A) is located on the other side in the axial direction with respect to the rotor magnet end face (42A), or the finger end face (29A) facing the one side of each of the plurality of fingers (29) that hold the stator magnet (22) provided on the teeth (26) of the stator (20) from both circumferential sides is located on the other side with respect to the tooth end face (26A) facing the one side of the teeth (26).

[0065] According to the inventors' findings, by positioning the end faces (32A, 33A) of the magnetic pole pieces on the other axial side with respect to the end face (42A) of the rotor magnet, the eddy current loss on one axial side of the magnetic pole piece (31) is reduced. Also, by positioning the finger end face (29A) on the other axial side with respect to the tooth end face (26A), the eddy current loss on one axial side of the stator (20) is reduced. Therefore, according to the configuration of 1) above, a magnetic gear rotating machine (10) with reduced eddy current loss can be realized.

[0066] 2) In some embodiments, the magnetic gear rotating machine (10) described in 1) above, the stator (20) includes a plurality of the stator magnets (22), each of the stator magnets (22) has a stator magnet end face (22A) facing the one side, the stator magnet end face (22A) is located on the other side with respect to the rotor magnet end face (42A).

[0067] According to the inventors' findings, by positioning the stator magnet end face (22A) on the other axial side with respect to the rotor magnet end face (42A), the eddy current loss in the magnetic pole piece (31) can be reduced. Also, the axial length of the stator magnet (22) can be reduced, thus realizing cost reduction. Therefore, according to the configuration of 2) above, a magnetic gear rotating machine (10) that achieves both reduction of eddy current loss and cost reduction can be realized.

[0068] 3) In some embodiments, the magnetic gear rotating machine (10) described in 2) above, the stator magnet end face (22A) is provided at the same axial position as the magnetic pole piece end faces (32A, 33A), or at an axial position between the magnetic pole piece end faces (32A, 33A) and the rotor magnet end face (42A).

[0069] According to the findings of the inventors, the portion of the stator magnet (22) on one side of the end faces of the magnetic pole pieces (32A, 33A) contributes little to the generation of magnetic transmission torque in the magnetic gear rotating machine (10). Therefore, according to the configuration of 3) above, it is possible to reduce the extra stator magnet (22) that contributes little to the generation of magnetic transmission torque, and the cost of the magnetic gear rotating machine (10) can be reduced.

[0070] 4) In some embodiments, it is the magnetic gear rotating machine (10) described in 1) above, At least a part of the end faces of the magnetic pole pieces (32A, 33A) is located on the other side with respect to the end face of the rotor magnet (42A), The magnetic pole piece (31) extends in the axial direction and includes a stator-side facing surface (36, 360) facing the stator (20), extends in the axial direction and includes a rotor-side facing surface (37, 370) facing the rotor (40), The stator-side facing surface (36, 360) is longer in the axial direction than the rotor-side facing surface (37, 370).

[0071] According to the configuration of 4) above, since the stator-side facing surface (36, 360) is longer in the axial direction than the rotor-side facing surface (37, 370), while at least a part of the end faces of the magnetic pole pieces (32A, 33A) is located on the other side in the axial direction with respect to the end face of the rotor magnet (42A), the axial length of the stator-side facing surface (36, 360) can be increased. Therefore, while suppressing the eddy current loss in the magnetic pole piece (31), it is possible to suppress a decrease in the transmission torque in the magnetic gear rotating machine (10). Thus, a magnetic gear rotating machine (10) that can reduce the eddy current loss and ensure the magnetic transmission torque is realized.

[0072] 5) In some embodiments, it is the magnetic gear rotating machine (10) described in 4) above, Each of the magnetic pole pieces (31) includes a first magnetic pole piece end portion (331) that is the end portion on the one side, The end portion (331) of the first magnetic pole piece has a plurality of electromagnetic steel sheets (35) laminated so that the radial positions of the end portions (355A, 355B) on the stator (20) side are aligned. The plurality of electromagnetic steel sheets (35) include a first electromagnetic steel sheet (35A) forming a part of the rotor-side facing surfaces (37, 370), and a second electromagnetic steel sheet (35B) provided at a radial position on the stator (20) side rather than the rotor-side facing surfaces (37, 370).

[0073] According to the configuration of 5) above, it is possible to achieve both reduction of eddy current loss and securing of magnetic transmission torque with a simple configuration in which a plurality of electromagnetic steel sheets (35) having different radial lengths are laminated.

[0074] 6) In some embodiments, there is provided the magnetic gear rotating machine (10) according to 4) or 5) above, wherein the stator (20) includes a plurality of the stator magnets (22), each of the stator magnets (22) has a stator magnet end face (22A) facing the one side, and the stator magnet end face (22A) is provided at the same axial position as the end (366A) on the one side of the stator-side facing surface (36, 360), or at an axial position between the end (366A) on the one side of the stator-side facing surface (36, 360) and the end (377A) on the one side of the rotor-side facing surface (37, 370).

[0075] According to the configuration of 6) above, it is possible to reduce the portion of the stator magnet (22) that hardly contributes to the magnetic transmission torque, and thus to realize cost reduction of the magnetic gear rotating machine (10).

[0076] 7) In some embodiments, there is provided the magnetic gear rotating machine (10) according to any one of 1) to 6) above, wherein at least a part of the magnetic pole piece end faces (32A, 33A) is located on the other side with respect to the rotor magnet end face (42A). The axial distances (dimensions La1 and Lb1) from the end faces (32A, 33A) of the magnetic pole pieces to the end face (42A) of the rotor magnet are 0.5% or more and 10% or less of the axial length (dimension Lr) of the rotor magnet (42).

[0077] According to the findings of the inventors, when the axial distances (dimensions La1 and Lb1) from the end faces (32A, 33A) of the magnetic pole pieces to the end face (42A) of the rotor magnet are 0.5% or more and 10% or less of the axial length (dimension Lr) of the rotor magnet (42), the effect of reducing the eddy current loss in the magnetic pole piece (31) can be improved. Therefore, according to the configuration of 7) above, a magnetic gear-driven rotating machine (10) with more effectively reduced eddy current loss is realized.

[0078] 8) In some embodiments, the magnetic gear-driven rotating machine (10) according to any one of 1) to 7) above, At least a part of the end faces (32A, 33A) of the magnetic pole pieces is located on the other side in the axial direction with respect to the end face (42A) of the rotor magnet, Each of the magnetic pole pieces (31) faces the rotor (40) with an air gap (second air gap G2) therebetween, The axial distances (dimensions La1 and Lb1) from the end faces (32A, 33A) of the magnetic pole pieces to the end face (42A) of the rotor magnet are 50% or more and 1200% or less of the facing distance (dimension Ls) between the magnetic pole piece (31) and the rotor (40).

[0079] According to the findings of the inventors, when the axial distances (dimensions La1 and Lb1) from the end faces (32A, 33A) of the magnetic pole pieces to the end face (42A) of the rotor magnet are 50% or more and 1200% or less of the facing distance (dimension Ls) between the magnetic pole piece (31) and the rotor (40), the effect of reducing the eddy current loss in the magnetic pole piece (31) can be improved. Therefore, according to the configuration of 8) above, a magnetic gear-driven rotating machine (10) with more effectively reduced eddy current loss is realized.

[0080] 9) In some embodiments, there is provided a magnetic gear-driven rotating machine (10) according to any one of 1) to 8) above, wherein the finger end face (29A) is located on the other side with respect to the tooth end face (26A), and the axial distance (dimension Lt1) from the finger end face (29A) to the tooth end face (26A) is 0.5% or more and 4% or less of the axial length (dimension Le) of the tooth (26).

[0081] According to the findings of the inventors, when the axial distance (dimension Lt1) from the finger end face (29A) to the tooth end face (26A) is 0.5% or more and 4% or less of the axial length (dimension Le) of the tooth (26), eddy current loss in the stator (20) can be reduced. Therefore, according to the configuration of 9) above, a magnetic gear-driven rotating machine (10) with more effectively reduced eddy current loss is realized.

[0082] 10) In some embodiments, there is provided a magnetic gear-driven rotating machine (10) according to any one of 1) to 9) above, wherein the finger end face (29A) is located on the other side with respect to the tooth end face (26A), and the axial distance (dimension Lt1) from the finger end face (29A) to the tooth end face (26A) is 3% or more and 25% or less of the circumferential length (dimension Lw) of the tip of the tooth (26).

[0083] According to the findings of the inventors, when the axial distance (dimension Lt1) from the finger end face (29A) to the tooth end face (26A) is 3% or more and 25% or less of the circumferential length (dimension Lw) of the tip of the tooth (26), eddy current loss in the stator (20) can be reduced. Therefore, according to the configuration of 10) above, a magnetic gear-driven rotating machine (10) with more effectively reduced eddy current loss is realized.

[0084] 11) A power generation system (1A) according to at least one embodiment of the present disclosure is a prime mover (2) and, any one of the magnetic gear rotating machines (10) from 1) to 10) above, as a magnetic gear generator (10A) configured to be driven by an input from the prime mover (2) to generate electricity, and comprises.

[0085] According to the configuration of 11) above, for the same reason as in 1) above, a power generation system (1A) with reduced eddy current loss can be realized.

[0086] 12) A drive system (1B) according to at least one embodiment of the present disclosure includes any one of the magnetic gear rotating machines (10) from 1) to 10) above, as a magnetic gear motor (10B) configured to output power, and a drive unit (8) configured to be driven by the power output from the magnetic gear rotating machine (10), and comprises.

[0087] According to the configuration of 12) above, for the same reason as in 1) above, a drive system (1B) with reduced eddy current loss can be realized.

[0088] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and also includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.

[0089] In this specification, expressions representing relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent a state of being relatively displaced with a tolerance or an angle or distance that allows the same function to be obtained. For example, expressions representing that things such as "identical", "equal", and "homogeneous" are in an equal state not only strictly represent an equal state, but also represent a state in which there is a tolerance or a difference that allows the same function to be obtained. In addition, in this specification, expressions representing shapes such as a rectangular shape or a cylindrical shape represent not only the shapes such as a rectangular shape or a cylindrical shape in a geometrically strict sense, but also shapes including concave and convex portions, chamfered portions, etc. within the range where the same effects can be obtained. In addition, in this specification, the expressions "comprises", "includes", or "has" for one component are not exclusive expressions excluding the existence of other components.

Description of Reference Numerals

[0090] 1A: Power generation system 1B: Drive system 2: Prime mover 8: Drive unit 10: Magnetic gear rotating machine 10A: Magnetic gear generator 10B: Magnetic gear motor 20: Stator 22: Stator magnet 22A: Stator magnet end face 26: Teeth 26A: Teeth end face 29: Fingers 29A: Fingers end face 30: Pole piece rotor 31: Pole piece 32A, 33A: Pole piece end faces 35: Electromagnetic steel sheet 35A: First electromagnetic steel sheet 35B: Second electromagnetic steel sheet 36, 360: Stator side opposing surfaces 37, 370: Rotor side opposing surfaces 40: Rotor 42: Rotor magnet 42A: Rotor magnet end face 331: First pole piece end 355A, 355B: Ends 377A, 377B: Ends G2: Second air gap

Claims

1. A stator; a rotor including a plurality of rotor magnets; a pole piece rotor including a plurality of pole pieces disposed radially between the stator and the rotor; Each of the pole pieces has a pole piece end face facing one side in the axial direction, Each of the rotor magnets has a rotor magnet end face facing the one side, At least a part of the pole piece end face is located on the other side in the axial direction with respect to the rotor magnet end face, or a finger end surface facing the one side of each of a plurality of fingers that sandwich and hold the stator magnets provided on the teeth of the stator from both sides in the circumferential direction is located on the other side of a tooth end surface facing the one side of the teeth. Magnetic geared rotating machinery.

2. the stator includes a plurality of the stator magnets, Each of the stator magnets has a stator magnet end face facing the one side, The stator magnet end face is located on the other side of the rotor magnet end face.

2. The magnetic-geared rotating machine according to claim 1.

3. The stator magnet end faces are located at the same axial position as the pole piece end faces or at an axial position between the pole piece end faces and the rotor magnet end faces.

3. The magnetic-geared rotating machine according to claim 2.

4. At least a portion of the pole piece end face is located on the other side with respect to the rotor magnet end face, The pole piece is a stator-side facing surface extending in the axial direction and facing the stator; a rotor-side facing surface extending in the axial direction and facing the rotor, The stator-side facing surface is longer in the axial direction than the rotor-side facing surface.

2. The magnetic-geared rotating machine according to claim 1.

5. Each of the pole pieces includes a first pole piece end that is an end on one side, The first pole piece end portion has a plurality of electromagnetic steel plates laminated so that the radial positions of the ends of the stator side are aligned, The plurality of electromagnetic steel sheets include A first electromagnetic steel sheet forming a part of the rotor side facing surface; a second electromagnetic steel plate provided at a radial position closer to the stator than the rotor-side opposing surface; 5. The magnetic-geared rotating machine according to claim 4.

6. the stator includes a plurality of the stator magnets, Each of the stator magnets has a stator magnet end face facing the one side, The stator magnet end surface is provided at the same axial position as the end of the one side of the stator side facing surface, or at an axial position between the end of the one side of the stator side facing surface and the end of the one side of the rotor side facing surface.

6. The magnetic-geared rotating machine according to claim 4 or 5.

7. At least a portion of the pole piece end face is located on the other side with respect to the rotor magnet end face, The axial distance from the pole piece end face to the rotor magnet end face is 0.5% or more of the axial length of the rotor magnet and 10% or less of the axial length of the rotor magnet.

7. A magnetic-geared rotating machine according to claim 1.

8. At least a portion of the pole piece end face is located on the other side with respect to the rotor magnet end face, Each of the pole pieces faces the rotor across an air gap; The axial distance from the end face of the pole piece to the end face of the rotor magnet is 50% or more and 1200% or less of the opposing distance between the pole piece and the rotor.

8. A magnetic-geared rotating machine according to any one of claims 1 to 7.

9. the finger end surface is located on the other side with respect to the teeth end surface, An axial distance from the finger end face to the tooth end face is 0.5% or more of an axial length of the tooth and 4% or less of the axial length of the tooth.

9. A magnetic-geared rotating machine according to any one of claims 1 to 8.

10. the finger end surface is located on the other side with respect to the teeth end surface, The axial distance from the finger end face to the tooth end face is 3% or more of the circumferential length of the tip of the tooth and 25% or less of the circumferential length.

10. A magnetic-geared rotating machine according to any one of claims 1 to 9.

11. The prime mover, A magnetic-geared rotating machine according to any one of claims 1 to 10, as a magnetic-geared generator configured to be driven by an input from the prime mover to generate electricity; A power generation system comprising:

12. A magnetic-geared rotating machine according to any one of claims 1 to 10 as a magnetic-geared motor configured to output power; a drive unit configured to be driven by the power output from the magnetic-geared rotating machine; A drive system comprising:

Images