Rotor and rotary electric machine

Abstract

The present invention is able to provide a rotor that suppresses deformation of a rotor core and has higher centrifugal force resistance.　Provided is an annular rotor which has a housing extending in the outer circumferential direction from the vicinity of a rotating shaft and a rotor core fixed to the outer circumferential side end of the housing, and in which slots are continuously provided in the circumferential direction, wherein: the rotor core has a bridge part and a pair of holding parts disposed substantially in line symmetry with respect to a neutral line connecting the center of the rotating shaft and the center of gravity of the rotor core, and a body part positioned on the outer circumferential side of the bridge part; the holding parts are positioned inside the housing when fixed; the bridge part is respectively provided between the holding parts and the body part at positions sandwiched between permanent magnets embedded in the rotor core in the circumferential direction; and the holding parts and the bridge parts are disposed so that the center of gravity of each holding part is positioned substantially on the axis of the center axis of the bridge part that connects the center point of an inner diameter side end section and the center point of an outer circumferential side end section of the bridge part.

Description

Rotor and rotating electric machine

[0001] The present invention relates to a rotor and a rotating electric machine. This invention claims priority from Japanese Patent Application No. 2023-218020, filed on December 25, 2023, and the contents of that application are incorporated by reference into this application in designated states where incorporation by reference of documents is permitted.

[0002] In recent years, the development of ultra-multi-pole motors aimed at achieving high rotation speeds for air mobility and various other devices has progressed. However, as the rotor size and rotation speeds increase due to the ultra-multi-pole motors, ensuring the rotor core's strength to withstand centrifugal force has become an essential issue.

[0003] In addition, Patent Document 1 describes technology related to the rotor of a rotating electric machine as follows: "The rotor of a rotating electric machine has a rotor core formed by stacking a plurality of annular steel plates in the axial direction, a plurality of permanent magnets embedded inside the rotor core at a predetermined distance in the circumferential direction, and a plurality of openings that penetrate the rotor core in the axial direction. The openings are arranged line-symmetrically with respect to the circumferential magnetic pole center of the permanent magnets arranged inside the rotor core, and two or more pillar portions that connect an inner beam portion located on the inner side of the opening and an outer beam portion located on the outer side are arranged line-symmetrically with respect to the circumferential center line of the opening."

[0004] JP 2011-259688 A

[0005] Rotors have rotor cores with various types of structures. For example, in rotors with a structure in which the rotor core is fixed by fitting or pinning to the outer periphery of a housing connected to a rotating shaft, stress generated by centrifugal force can cause deformation of a portion of the rotor core. Specifically, in rotor cores with bridge portions located between magnet holes of permanent magnets embedded in the rotor core and extending from a retaining portion, which is the fitting portion with the housing, toward the outer periphery of the rotor core, bending stress can cause deformation of the bridge portions. Therefore, in such rotors, there is a demand for suppressing deformation of the rotor core by reducing the bending stress acting on the bridge portions.

[0006] Patent Document 1 discloses a structure for ensuring the strength of the outer beam portion so that it does not expand due to centrifugal force when the rotor rotates. However, the technology in this document does not target rotor structures that have a retaining portion that fits into a housing and a bridge portion that extends from the retaining portion toward the outer periphery of the rotor. Therefore, it is difficult to adopt the technology in this document as is.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a rotor that suppresses deformation of the rotor core and has higher centrifugal force resistance strength.

[0008] The present application includes multiple means for resolving at least part of the above-described problems, examples of which are as follows: A rotor according to one aspect of the present invention that resolves the above-described problems is an annular rotor having slots connected in the circumferential direction, the rotor core including a housing extending radially outward from near the rotation axis and a rotor core fixed to the outer peripheral end of the housing, the rotor core having a pair of retaining portions and a bridge portion disposed substantially symmetrically with respect to a neutral line connecting the center of the rotation axis and the center of gravity of the rotor core, and a barrel portion disposed on the outer peripheral side of the bridge portion, the retaining portions being located within the housing when fixed, the bridge portion being provided between the retaining portions and the barrel portion at a position sandwiched between permanent magnets embedded circumferentially within the rotor core, and the retaining portions and bridge portions being disposed so that the center of gravity of the retaining portions is located substantially on a central axis of the bridge portion that connects the center point of the inner diameter end of the bridge portion to the center point of the outer diameter end of the bridge portion.

[0009] According to the present invention, it is possible to provide a rotor that suppresses deformation of the rotor core and has higher centrifugal force resistance strength.

[0010] Problems, configurations, effects, and the like other than those described above will become clear from the following description of the embodiments.

[0011] FIG. 1 is an overall view of a rotor. FIG. 2 is an enlarged perspective view of a housing and rotor core for one pole. FIG. 3 is an enlarged sectional view of a rotor core according to a first embodiment. FIG. 4 is a partially enlarged view of a rotor core according to the first embodiment. FIG. 5 is a diagram for explaining the positional relationship between the center of gravity of a retaining portion and the central axis of a bridge portion. FIG. 6 is a graph showing the relationship between the ratio of L1 to L2 and equivalent stress / fatigue limit. FIG. 7 is an enlarged sectional view of a rotor core according to a second embodiment. FIG. 8 is a partially enlarged view of a rotor core according to the second embodiment. FIG. 9 is a diagram for explaining the positional relationship between the center of gravity of a retaining portion and the central axis of a bridge portion.

[0012] The following embodiments are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Furthermore, unless otherwise specified, each component may be singular or plural.

[0013] Furthermore, in order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0014] In addition, when there are multiple components having the same or similar functions, they may be described by using the same reference numeral with different subscripts, or when there is no need to distinguish between these multiple components, the subscripts may be omitted.

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] 1 is an overall view of a rotor 100 according to this embodiment. As shown in the figure, the rotor 100 has a ring-shaped configuration in which a predetermined number of slots (66 slots (corresponding to 66 poles) in the illustrated example) are connected in the circumferential direction, with each slot consisting of a housing 10 extending from an edge H2 of an insertion hole H1 of a shaft (not shown) that serves as a rotating axis toward the outer periphery of the rotor 100 and a rotor core 20 fitted and fixed to the outer periphery end of the housing 10.

[0017] The rotor core 20 corresponds to the magnetic pole portion of the rotor 100, which is formed by laminating a predetermined number of electromagnetic steel plates in the axial direction. Although not shown, a stator (stator) having a stator core (stator core) around which a stator winding (stator coil) is wound is coaxially arranged on the outer circumferential surface of the rotor 100 at a predetermined interval. The rotor 100 and stator constitute a part of a rotating electric machine (motor) used in air mobility and various other devices.

[0018] 2 is an enlarged perspective view of the housing 10 and rotor core 20 for one pole. As shown in the figure, the housing 10 has a vertically elongated portion 11 that is elongated in the axial direction (Y-axis direction) of the rotor 100, and a horizontally elongated portion 12 that is elongated in the horizontal direction (Z-axis direction) that is substantially perpendicular to the axial direction of the rotor 100. The rotor core 20 has a length that extends from the upper end to near the lower end of the vertically elongated portion 11, and is fixed by being fitted into the vertically elongated portion 11.

[0019] Specifically, rotor core 20 has an axial length from the upper end to the lower end and is provided with a convex portion (a retaining portion, described later) that fits into housing 10. Furthermore, vertically elongated portion 11 of housing 10 has an axial length that is at least the same as (or longer than) the axial length of rotor core 20 and is provided with a concave portion that receives the convex portion of rotor core 20. Furthermore, by inserting the convex portion of rotor core 20 into the concave portion of housing 10 in the axial direction, rotor core 20 is fitted and fixed to the outer peripheral surface of housing 10.

[0020] Fig. 3 is an enlarged cross-sectional view of the rotor core according to this embodiment, and Fig. 4 is an enlarged partial view of the rotor core.

[0021] As shown in these figures, the rotor core 20 has a holding portion 21 , a bridge portion 22 , a body portion 23 , and ear portions 24 .

[0022] The rotor core 20 has a structure that is approximately plane-symmetrical with respect to a neutral plane that is defined in the axial direction (the Y-axis direction shown in the figure) along a straight line connecting the center A of the rotation axis and the center of gravity G1 of the rotor core 20. In other words, the rotor core 20 has a pair of retaining portions 21, bridge portions 22, and ear portions 24 that are arranged approximately line-symmetrically with respect to a neutral line C1, which is a straight line that defines the neutral plane, and a body portion 23. Note that the pair of retaining portions 21 and bridge portions 22 are each spaced a predetermined distance from the neutral line C1, and one retaining portion 21 and bridge portion 22 and the other retaining portion 21 and bridge portion 22 are formed independently from each other in the inner circumferential direction from the body portion 23.

[0023] The retaining portion 21 is a convex portion that is located inside the housing 10 when the rotor core 20 is fitted into the housing 10. Specifically, the retaining portion 21 is substantially triangular in shape and has contact surfaces 21a, 21b, and 21c that come into contact with the housing 10. Furthermore, the contact surfaces 21b and 21c narrow at an acute angle from both ends of the contact surface 21a toward the outer periphery. Therefore, even if a load acts in the outer periphery direction due to centrifugal force, the retaining portion 21 catches on the inner surface of the concave portion of the housing 10, preventing the rotor core 20 from coming off the housing 10.

[0024] The bridge portion 22 is located between the outer peripheral end of the holding portion 21 and the body portion 23, and is provided at a position where it is sandwiched between the first permanent magnet M1 and the second permanent magnet M2 when these magnets M1 and M2 are embedded in the circumferential direction in a Halbach array in the rotor core 20. The width of the bridge portion 22 in the circumferential direction is formed to be narrower than the width of the abutment surface 21 a.

[0025] The body portion 23 is a portion located between the outer peripheral end of the bridge portion 22 and the outer peripheral surface of the rotor 100. The body portion 23 also has protruding ear portions 24 on both ends in the circumferential direction.

[0026] The first permanent magnet M1 and the second permanent magnet M2 embedded in the rotor core 20 are fixed by being sandwiched between the bridge portion 22, the body portion 23, and the housing 10. Specifically, the first permanent magnet M1 is fixed by being sandwiched between the outer periphery of the housing 10, the inner side of the bridge portion 22, and one side of the body portion 23 in the inner diameter direction of the rotor 100. The second permanent magnet M2 is fixed by being sandwiched between two adjacent slots. Specifically, the second permanent magnet M2 is fixed by being sandwiched between the outer periphery of the housing 10, the outer side of the bridge portion 22, and the ears 24 in one slot, and the bridge portion 22, the body portion 23, and the ears 24 of the rotor core 20 in the other adjacent slot.

[0027] The first permanent magnet M1 and the second permanent magnet M2 are embedded in the circumferential direction in a Halbach array, and the first permanent magnet M1 has a generally rectangular shape that is longer in the circumferential direction than the length of the rotor 100 in the circumferential direction. The second permanent magnet M2 also has a generally rectangular shape that is longer in the circumferential direction than the length of the rotor 100 in the circumferential direction.

[0028] Next, the positional relationship between the center of gravity of the holding portion 21 and the central axis of the bridge portion 22 will be described with reference to FIGS.

[0029] 5 is a diagram illustrating the positional relationship between the center of gravity of the holding portion and the central axis of the bridge portion 22. The central axis C2 of the bridge portion 22 is defined by a straight line connecting the center point B1 of the inner diameter end of the rotor 100 to the center point B2 of the outer diameter end.

[0030] In order to explain the distance L1 between the center of gravity 21g of the holding portion 21 and the central axis C2 of the bridge portion 22, FIG. 5 shows an example in which the positions of the two are shifted.

[0031] In the rotor core 20 of the rotor 100 according to this embodiment, when the distance from the center of gravity 21g of the holding portion 21 to the central axis C2 of the bridge portion 22 is defined as L1, the holding portion 21 and the bridge portion 22 are provided so that the distance L1 is a value closer to 0 (zero). That is, as shown in FIG. 4 , the center of gravity 21g of the holding portion 21 is disposed so as to be positioned substantially on the central axis C2 of the bridge portion 22.

[0032] In this way, by arranging the center of gravity 21g of the holding portion 21 so as to be positioned substantially on the central axis C2 of the bridge portion 22, it is possible to reduce the bending moment (bending stress) acting on the bridge portion 22 when the rotor 100 rotates. As a result, it is possible to suppress deformation of the bridge portion 22 that would otherwise bulge in the circumferential direction due to the action of the bending moment.

[0033] It is most preferable that L1 is approximately 0 (zero), that is, that the center of gravity 21g of the retaining portion 21 is located on the central axis C2 of the bridge portion 22. However, if the distance from the neutral line C1 that passes through the center of gravity G1 of the rotor core 20 and divides the rotor core 20 into approximately two equal parts to the center of gravity 21g of the retaining portion 21 is defined as L2, then the position of the center of gravity 21g of the retaining portion 21 relative to the central axis C2 of the bridge portion 22 may be set within a range that satisfies the condition L1 / L2<0.2. The condition of less than 0.2 is based on a value derived from the relationship between equivalent stress / fatigue limit and L1 / L2 (the ratio of L1 to L2).

[0034] 6 is a graph showing the relationship between the ratio of L1 to L2 and the equivalent stress / fatigue limit. As shown in the figure, the vertical axis of the graph represents the equivalent stress / fatigue limit, and the horizontal axis represents the distance L1 / L2. Simply put, a value of 1.0 or more for the equivalent stress / fatigue limit indicates that the rotor core 20 will break (deform) or will break (deform) after a predetermined load period.

[0035] As shown in Fig. 6, the closer L1 / L2 is to 0 (zero), the lower the value of the equivalent stress / fatigue limit. In other words, Fig. 6 shows that the closer L1 is to 0 (zero) by positioning the center of gravity 21g of the retaining portion 21 substantially on the central axis C2 of the bridge portion 22, the more difficult it is for the rotor core 20 to deform.

[0036] The structure of the rotor core of the rotor according to the first embodiment has been described above. With such a rotor, deformation of the rotor core is suppressed, and a rotor with higher centrifugal force resistance strength can be provided.

[0037] In particular, it is most preferable that the center of gravity of the holding part is located on the central axis of the bridge part, but by setting the position of the center of gravity of the holding part relative to the central axis of the bridge part within a range that satisfies the condition L1 / L2 < 0.2, deformation of the rotor core can be suppressed even when a load due to centrifugal force is applied.

[0038] In addition, although the holding portions 21 in the first embodiment have been shown as a pair of structures that are substantially symmetrical about the neutral line C1, for example, the pair of holding portions 21 may be connected to each other and integrated, or a set of holding portions formed by a plurality of holding portions 21 with different shapes may be used.

[0039] Second Embodiment A rotor 100 according to this embodiment has a configuration in which a rotor core 30 is fixed to an outer peripheral end of a housing 10 by pinning.

[0040] Fig. 7 is an enlarged cross-sectional view of a rotor core according to a second embodiment. Fig. 8 is an enlarged partial view of a rotor core according to a second embodiment.

[0041] As shown in these figures, the rotor core 30 has a retaining portion 31, pin holes 32, bridge portions 33, magnet holes 34, a body portion 35, and ear portions 36. Note that the same components and objects as those of the rotor 100 shown in the first embodiment, such as the neutral plane and neutral line, are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0042] As in the first embodiment, the rotor core 30 has a structure that is approximately plane-symmetric (line-symmetric) with respect to a neutral plane (neutral line C3) defined in the axial direction (the Y-axis direction shown) along a straight line connecting the center A of the rotation axis and the center of gravity G2 of the rotor core 30.

[0043] The retaining portion 31 is a portion that is located within the housing 10 when the rotor core 30 is pinned to the housing 10. Specifically, the retaining portion 31 has an arc-shaped inner diameter end portion and a pin hole 32 located approximately in the center. Furthermore, magnet holes 34 in which first permanent magnets M1 are embedded are provided at predetermined intervals on the outer circumferential direction of the retaining portion 31. Regarding the retaining portion 31, if a portion located in the inner diameter direction of the rotor 100 is defined as the front portion and a portion located in the outer circumferential direction is defined as the rear portion, based on a partition line D2 that passes through the center point D1 of the pin hole 32 and is approximately perpendicular to the neutral line C3, one retaining portion 31 and the other retaining portion 31 are arranged approximately symmetrically with respect to the neutral line C3, and their front and rear portions are connected to each other.

[0044] The pin holes 32 are through holes into which pins (not shown) are inserted to fix the rotor core 30 to the housing 10. The pin holes 32 are provided so that their centers are located approximately on a neutral line C3 that passes through the center of gravity G2 of the rotor core 30 and divides the rotor core 30 into approximately two equal parts. The diameter of the pin holes 32 is set to an arbitrary diameter depending on the size of the pins to be inserted. By being pinned to the housing 10, the rotor core 30 is structured so that it will not come off the housing 10 even when a load acts in the outer circumferential direction due to centrifugal force.

[0045] The bridge portion 33 is a portion located between the outer peripheral end of the holding portion 31 and the body portion 35, and is positioned so as to be sandwiched between the first permanent magnet M1 and the second permanent magnet M2 embedded in the rotor core 30.

[0046] The body portion 35 is a portion located between the outer peripheral end of the bridge portion 33 and the outer peripheral surface of the rotor 100. The body portion 35 also has protruding ears 36 on both ends in the circumferential direction.

[0047] The rotor core 30 also has magnet holes 34 in which the first permanent magnets M1 are embedded between the retaining portion 31 and the body portion 35. The position of the second permanent magnets M2 is the same as in the first embodiment, so a detailed description thereof will be omitted. The first permanent magnets M1 and the second permanent magnets M2 are embedded in the rotor core 30 in a Halbach array, as in the first embodiment.

[0048] Next, the positional relationship between the center of gravity of the holding portion 31 and the central axis of the bridge portion 33 will be described with reference to FIGS.

[0049] 9 is a diagram illustrating the positional relationship between the center of gravity of the holding portion and the central axis of the bridge portion 33. The central axis C4 of the bridge portion 33 is defined by a straight line connecting the center point B3 of the inner diameter end of the rotor 100 to the center point B4 of the outer diameter end.

[0050] In order to explain the distance L1 between the center of gravity 31g of the holding portion 31 and the central axis C4 of the bridge portion 33, FIG. 9 shows an example in which the positions of the two do not coincide.

[0051] In the rotor core 30 of the rotor 100 according to this embodiment, when the distance from the center of gravity 31g of the holding portion 31 to the central axis C4 of the bridge portion 33 is defined as L1, the holding portion 31 and the bridge portion 33 are provided so that the distance L1 is a value closer to 0 (zero). In other words, the center of gravity 31g of the holding portion 31 is disposed so as to be positioned substantially on the central axis C4 of the bridge portion 33.

[0052] As in the first embodiment, if the distance from the neutral line C3 that passes through the center of gravity G2 of the rotor core 30 and divides the rotor core 30 approximately in half to the center of gravity 31g of the retaining portion 31 is L2, the position of the center of gravity 31g of the retaining portion 31 relative to the central axis C4 of the bridge portion 33 can be set within the range where L1 / L2 < 0.2.

[0053] In this way, by setting the position of the center of gravity 31g of the holding portion 31 relative to the central axis C4 of the bridge portion 33 within the range where L1 / L2 is at least less than 0.2, the bending moment (bending stress) acting on the bridge portion 33 when the rotor 100 rotates can be reduced, and a rotor 100 with higher centrifugal force resistance can be provided.

[0054] In addition, in the second embodiment, one pin hole 32 is provided in the rotor core 30, but this is not limited to this, and for example, the rotor core 30 may be provided with multiple pin holes for fixing to the housing.

[0055] Furthermore, the present invention is not limited to the above-described embodiments and modifications, and includes various modifications within the scope of the same technical concept. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0056] 100: rotor, 10: housing, 20: rotor core according to first embodiment, 21: retaining portion, 22: bridge portion, 23: trunk portion, 24: ear portion, C1: neutral line, C2: central axis of bridge portion, G1: center of gravity of rotor core, 21G: center of gravity of retaining portion, 30: rotor core according to second embodiment, 31: retaining portion, 32: pin hole, 33: bridge portion, 34: magnet hole, 35: trunk portion, 36: ear portion, C3: neutral line, C4: central axis of bridge portion, G2: center of gravity of rotor core, 31G: center of gravity of retaining portion, L1: distance from center of gravity of retaining portion to central axis of bridge portion, L2: distance from center of gravity of retaining portion to neutral line

Claims

1. A rotor having an annular shape in which slots are connected in the circumferential direction, the rotor being configured to include a housing extending in the outer circumferential direction from near the rotation axis and a rotor core fixed to the outer circumferential side end of the housing, wherein the rotor core includes a pair of holding portions and bridge portions arranged substantially line-symmetrically with respect to a neutral line connecting the center of the rotation axis and the center of gravity of the rotor core, and a body portion located on the outer circumferential side of the bridge portion, the holding portion is located within the housing when fixed, the bridge portion is provided between the holding portion and the body portion and is sandwiched between permanent magnets embedded in the circumferential direction within the rotor core, and the holding portion and the bridge portion are arranged such that the center of gravity of the holding portion is located substantially on the central axis of the bridge portion connecting the center point of the inner diameter side end portion to the center point of the outer circumferential side end portion of the bridge portion. A rotor characterized by the above.

2. The rotor according to claim 1, wherein when the distance from the center of gravity of the holding portion to the central axis of the bridge portion is L1 and the distance from the center of gravity of the holding portion to the neutral line is L2, the center of gravity of the holding portion and the central axis of the bridge portion are set such that the relationship L1 / L2 < 0.2 holds. A rotor characterized by the above.

3. The rotor according to claim 1, wherein the pair of holding portions and bridge portions are separated from each other by a predetermined distance from the neutral line and are independently formed in the inner diameter direction from the body portion, and the holding portion is fitted and fixed to the housing. A rotor characterized by the above.

4. The rotor according to claim 1, wherein the pair of holding portions have an integrated structure connected to each other. A rotor characterized by the above.

5. The rotor according to claim 1, wherein the holding portion is provided with a pin hole, and in the outer circumferential direction of the holding portion, magnet holes for embedding magnets at a predetermined interval are provided. The holding portion has a front portion located in the inner diameter direction and a rear portion located in the outer circumferential direction with reference to a partition line passing through the substantially center point of the pin hole and substantially orthogonal to the neutral line, and the front portions and the rear portions of one holding portion and the other holding portion arranged substantially line-symmetrically with respect to the neutral line are connected to each other, and the rotor is fixed to the housing by pinning. A rotor characterized by the above.

6. A rotating electrical machine comprising an annular rotor in which slots having a housing extending in the outer peripheral direction from near the rotation axis and a rotor core fixed to the outer peripheral side end of the housing are connected in the circumferential direction, wherein the rotor core of the rotor has a pair of holding portions and bridge portions arranged substantially line-symmetrically with respect to a neutral line connecting the center of the rotation axis and the center of gravity of the rotor core, a body portion located on the outer peripheral side of the bridge portion, the holding portion is located in the housing when fixed, the bridge portion is provided between the holding portion and the body portion and is sandwiched between permanent magnets embedded in the circumferential direction in the rotor core, the holding portion and the bridge portion are arranged such that the center of gravity of the holding portion is located substantially on the central axis of the bridge portion connecting the center point of the inner diameter side end portion to the center point of the outer diameter side end portion of the bridge portion. A rotating electrical machine characterized by this.

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