ROTOR FOR ELECTRIC ROTARY MACHINE AND ELECTRIC ROTARY MACHINE

Abstract

Rotor for an electric rotary machine, comprising the following: a rotor core (21); a plurality of permanent magnets (22) which are provided on an outer peripheral area of ​​the rotor core (21) and are arranged apart from each other in the circumferential direction; a conductive element (23) that surrounds the rotor core (21) and the plurality of permanent magnets (22) as a whole; and a retaining element (24) that surrounds the rotor core (21), the plurality of permanent magnets (22) and the conductive element (23) as a whole, wherein the conductivity of the conductive element (23) is higher than the conductivity of the permanent magnet (22), the conductive element (23) has first and second opposing regions (231, 232) which are opposite each other across a gap in the circumferential direction, and An axially extending region (26) between the opposing areas, which exists between the first and second opposing areas (231, 232), is arranged within a circumferential direction area of ​​a region (25) between the magnets, which exists between permanent magnets (22) that are adjacent to each other in the circumferential direction and is arranged where there are no permanent magnets, and if a radial direction thickness of the conductive element (23) is specified as t, the resistivity of the conductive element (23) is specified as ρ, the permeability of the conductive element (23) as µ and the carrier angular frequency of the inverter used to drive the electric rotary machine (1) as ω c Given that the penetration depth of the conductive element (23) is specified as d, then d is defined as follows: d = 2 ρ ω c μ , and a ratio that fulfills the following: 0 < td ≤ 2 is obtained between t and d.

Description

Technical area

[0001] The invention relates to a rotor for an electric rotary machine in which permanent magnets are formed on an outer peripheral region of a rotor core of the rotor, and to an electric rotary machine. State of the art

[0002] In a conventional rotor for an electric rotating machine, in order to prevent a permanent magnet from detaching from the rotor core due to centrifugal force generated when the rotor rotates, the permanent magnet is formed at an outer peripheral portion of the rotor core, and the rotor core and the permanent magnet are covered as a whole with a fiber-reinforced plastic holding member from an outer side of the permanent magnet (see, for example, PTL 1).

[0003] Furthermore, when PWM (pulse width modulation) control using an inverter is implemented on a rotating electric machine used for high-speed rotation, harmonic magnetic flux is generated by a carrier frequency component, generating eddy currents in the rotor core and the permanent magnet. As a result, the motor generates heat. When the rotor generates heat, the temperature of the permanent magnet rises, resulting in demagnetization in the permanent magnet.

[0004] In a conventional rotor for an electric rotary machine proposed in the prior art, heat generation by the rotor is suppressed by interposing a high-conductivity cylindrical member having a higher conductivity than other constituent members such as a permanent magnet and a shaft between the permanent magnet and a holding member.

[0005] In this conventional rotor for an electric rotating machine, eddy currents are generated in the high-conductivity element, and the magnetic flux generated by the eddy currents cancels the harmonic magnetic flux of the carrier frequency component. Consequently, eddy current generation in the permanent magnet and the rotor core is prevented, and demagnetization of the permanent magnet is prevented (see, for example, PTL 2).

[0006] In another rotor for an electric rotary machine proposed in the prior art, manufacturing is simplified by dividing a cylindrical member with high conductivity arranged between a shaft and a permanent magnet into a plurality of conductive regions arranged in a circumferential direction (see, for example, PTL 3). BibliographyPatent literature [PTL 1] Japanese Patent Application Publication JP H10- 243 586 A [PTL 2] Japanese Patent Application Publication JP 2001- 78 378 A [PTL 3] Japanese Patent Application Publication JP 2011- 125 106 A.

[0007] Further prior art can be found in DE 11 2015 006 260 T5 and JP 2000- 60 042 A. Summary of the inventionTechnical problem

[0008] In a conventional rotor for a rotary electric machine disclosed in PTL 2, the cylindrical high-conductivity member must be manufactured with a reduced thickness in order to suppress an increase in the diameter of the rotary electric machine, and therefore, the manufacturing of the high-conductivity member is laborious.

[0009] Furthermore, in the conventional rotor for an electric rotary machine disclosed in PTL 3, the high-conductivity member is divided into a plurality of conductive regions, and therefore, the harmonic magnetic flux of the carrier frequency component passes through gaps between adjacent conductive regions to reach the permanent magnet and the shaft, with the result that the permanent magnet is demagnetized.

[0010] When adjacent conductive regions are brought into contact with each other to prevent the harmonic magnetic flux of the carrier frequency component from reaching the permanent magnet and the shaft, the contact resistance at the boundary between the respective conductive regions increases, so that heat is generated at the boundary between the conductive regions, and the heat from the boundary between the conductive regions is transferred to the permanent magnet, with the result that the permanent magnet is demagnetized.

[0011] This invention was conceived to solve the problems described above. It is therefore an object of the invention to provide a rotor for an electric rotary machine and an electric rotary machine that can be manufactured easily while preventing demagnetization of the permanent magnet. Solution to the problem

[0012] A rotor for a rotary electric machine according to the invention comprises: a rotor core; a plurality of permanent magnets formed at an outer peripheral portion of the rotor core and arranged apart from each other in the circumferential direction; a conductive member surrounding the rotor core and the plurality of permanent magnets as a whole;and a holding member surrounding the rotor core, the plurality of permanent magnets, and the conductive member as a whole, wherein the conductivity of the conductive member is higher than the conductivity of the permanent magnet, the conductive member has first and second opposing regions that oppose each other across a gap in the circumferential direction, and wherein a region between the opposing regions that exists between the first and second opposing regions is located only within a circumferential direction range of a region between the magnets that are adjacent to each other in the circumferential direction; Advantageous effects of the invention

[0013] In the rotor for a rotary electric machine and the rotary electric machine according to the invention, the conductive element can be incorporated into the rotor simply by winding the conductive element around the rotor core and the plurality of permanent magnets as a whole, and therefore the rotor can be easily manufactured. Furthermore, by coupling the harmonic magnetic flux generated by a stator to the conductive element, the value of the harmonic magnetic flux reaching the permanent magnets can be reduced.

[0014] By ensuring that the harmonic magnetic flux passing through the region between the opposing areas passes through the region between the magnets, the probability of the harmonic magnetic flux being coupled to the permanent magnet can be reduced. As a result, demagnetization of the permanent magnets can be prevented. Short description of the drawings Fig. 1 is a sectional view showing an electric rotary machine according to a first embodiment of the invention. Fig. 2 is a sectional view along the line II-II in Fig. 1. Fig. 3 is an enlarged view showing a part of a Fig. 1, wherein a region exists between the opposing areas. Fig. 4 is an enlarged view showing part of the Fig. 1 where a conductive element overlaps an outer peripheral surface of a permanent magnet. Fig. 5 is a partially enlarged view showing a rotor according to a first comparative example. Fig. 6 is a partially enlarged view showing a rotor according to a second comparative example. Fig. 7 is a sectional view showing another example of the rotor for a rotary electric machine according to the first embodiment of the invention. Fig. 8 is a perspective view showing another example of the rotor for a rotary electric machine according to the first embodiment of the invention, with a holding member omitted. Fig. 9 is an enlarged sectional view showing main parts of a rotor for a rotary electric machine according to a second embodiment of the invention. Fig. Figure 10 is a graph showing the relationship between a stress concentration factor for stresses present in a Fig. 9, and a circumferential extension of a region between the opposing areas. Fig. 11 is an enlarged sectional view showing main parts of a rotor for a rotary electric machine according to a third embodiment of the invention. Fig. 12 is an enlarged sectional view showing main parts of a rotor for a rotary electric machine according to a fourth embodiment of the invention. Fig. 13 is an enlarged sectional view showing main parts of a rotor for a rotary electric machine according to a fifth embodiment of the invention. Fig. 14 is a sectional view showing an electric rotary machine according to a sixth embodiment of the invention. Fig. 15 is a graph showing the relationship between a radial direction thickness of a conductive member according to a seventh embodiment of the invention and the losses occurring in the rotor when an inverter is driven. Fig. 16 is a view showing another example of the rotor for a rotary electric machine according to the first embodiment of the invention. Description of the embodiments

[0015] Preferred embodiments of the invention are described below with reference to the figures. First embodiment

[0016] Fig. Fig. 1 is a sectional view showing an electric rotary machine according to a first embodiment of the invention, and Fig. 2 is a sectional view along the line II-II in Fig. 1.According to the drawings, an electric rotary machine 1 comprises a rotor 2 and a cylindrical stator 3 which surrounds the rotor 2 via a gap in the radial direction. The rotor 2 and the stator 3 are arranged coaxially. Accordingly, the rotor 2 and the stator 3 have a common axis A. Furthermore, in this example, as shown in Fig. 2, the respective configurations of the rotor 2 and the stator 3 are symmetrical about an orthogonal line B which is orthogonal to the axis A at an axial direction center position of a stator core 4.

[0017] The stator 3 has the cylindrical stator core 4 formed of a magnetic material and stator coils 5 formed on the stator core 4.

[0018] The stator core 4 includes a cylindrical rear yoke 41 and a plurality of teeth 42 projecting toward a radially inner side from an inner peripheral portion of the rear yoke 41. The teeth 42 are arranged at intervals in the circumferential direction of the rotary electric machine 1. Grooves 43 are formed between the teeth 42 as spaces open toward the radially inner side of the stator 3.

[0019] The stator coils 5 are each arranged in the slots 43. As in Fig. As shown in Figure 2, the stator coils 5 have coil ends 5a that protrude from the stator core 4 in the axial direction, or in other words, in the direction along axis A. Current is supplied to the stator coils 5 by means of PWM control using an inverter. When power is supplied to the stator coils 5, a rotating magnetic field is generated in the stator 3.

[0020] The rotor 2 is capable of rotating about the axis A. Further, the rotor 2 includes: a shaft 21 serving as a rotor core, a plurality of permanent magnets 22 formed on an outer peripheral portion of the shaft 21, a plate-shaped conductive member 23 surrounding the shaft 21 and the plurality of permanent magnets 22 as a whole, and a sheet-like support member 24 surrounding the shaft 21, the plurality of permanent magnets 22, and the conductive member 23 as a whole.

[0021] The shaft 21 is a columnar member whose central axis is the axis A. Furthermore, the shaft 21 is formed of a magnetic material.

[0022] A plurality of permanent magnets 22 are formed at intervals in the circumferential direction of the rotor 2. In this example, four permanent magnets 22 are arranged at equal intervals in the circumferential direction of the rotor 2. The permanent magnets 22 are segment magnets that have an arcuate cross-section so that they extend around an outer peripheral surface of the shaft 21. An inter-magnet region 25 exists as a space between the permanent magnets 22 that are adjacent to each other in the circumferential direction. Rare earth magnets, far-earth magnets, or the like are used, for example, as the permanent magnets 22.

[0023] The conductive member 23 covers the permanent magnets 22 and the regions 25 between the magnets to overlap the respective outer peripheral surfaces of the permanent magnets 22. In other words, the conductive member 23 is arranged at a position closer to the stator 3 than the shaft 21 and the permanent magnets 22. As a result, the conductive member 23 is arranged between the support member 24 and the respective permanent magnets 22 and the regions 25 between the magnets. The conductivity of the conductive member 23 is set to be higher than the conductivity of the permanent magnet 22. For example, copper, aluminum, or the like can be used as the material for forming the conductive member 23.

[0024] Further, the conductive member 23 includes a first opposing portion 231 and a second opposing portion 232 that oppose each other across a gap in the circumferential direction of the rotor 2. A region 26 between the opposing portions exists as a space between the first opposing portion 231 and the second opposing portion 232. In this example, the region 26 between the opposing portions exists only at one location of the conductive member 23 in the circumferential direction of the rotor 2. Further, in this example, the region 26 between the opposing portions in the conductive member 23 is formed to extend along the axis A.

[0025] The support member 24 covers the shaft 21, the plurality of permanent magnets 22, and the conductive member 23 over the entire circumferential periphery of the rotor 2, overlapping an outer peripheral surface of the conductive member 23. As a result, the rotor 2 is reinforced, so that when the rotor 2 rotates at high speed, the permanent magnets 22 are not thrown off the shaft 21 due to centrifugal force. The support member 24 is formed of a non-magnetic material. For example, carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), titanium, stainless steel, or the like is used as the material for forming the support member 24.

[0026] As in Fig. 2, in this case the relation Lm = La = Lk = Ls results, where Lm denotes the axial direction extension of the permanent magnet 22, La denotes the axial direction extension of the conductive element 23, Lk denotes the axial direction extension of the holding element 24, and Ls denotes the axial direction extension of the stator 4.

[0027] Fig. 3 is an enlarged view showing a part of the rotor 2 shown in Fig. 1, the region 26 is formed between the opposing portions. The circumferential dimension d1 of the region 26 between the opposing portions is smaller than the circumferential dimension d2 of the region 25 between the magnets. Furthermore, the region 26 between the opposing portions is located only within a circumferential region of the region 25 between the magnets. In this example, the region 26 between the opposing portions is located at a circumferential center position of the region 25 between the magnets.

[0028] Next, procedures for assembling the rotor 2 will be described. After the plurality of permanent magnets 22 are mounted on the outer peripheral portion of the shaft 21, the plate-shaped conductive member 23 is wound around the shaft 21 and the plurality of permanent magnets 22 as a whole. As a result, the outer periphery of the plurality of permanent magnets 22 is covered by the conductive member 23. At this time, the respective end portions of the conductive member 23 are opposed across a gap in the circumferential direction, thus forming the first opposing portion 231 and the second opposing portion 232.

[0029] As a result, a gap serving as the region 26 is formed between the first opposing region 231 and the second opposing region 232. Next, the sheet-like holding member 24 is wound around the shaft 21, the plurality of permanent magnets 22, and the conductive member 23 as a whole, from the radially outer side of the conductive member 23. As a result, the outer periphery of the conductive member 23 is covered with the holding member 24, so that the rotor 2 is completed.

[0030] Next, the operation is described. When current is supplied to the stator coils 5 from the inverter using PWM control, a rotating magnetic field is generated in the stator 3. When the rotating magnetic field is generated in the stator 3, the rotor 2 rotates around the axis A.

[0031] The current supplied to the stator coils 5 by PWM control has a harmonic carrier component derived from a carrier frequency. When the current having the harmonic carrier component is supplied to the stator coils 5, a harmonic magnetic flux caused by the harmonic carrier component is generated by the stator 3, in addition to the fundamental magnetic flux, which contributes to the torque.

[0032] Fig. 4 is an enlarged view showing part of the Fig. 1 shows where the conductive element 23 overlaps the outer peripheral surface of the permanent magnet 22. When the harmonic magnetic flux P1 generated by the stator 3 is coupled to the conductive element 23, eddy currents C are generated in the conductive element 23. When the eddy currents C are generated in the conductive element 23, the magnetic flux P2 is generated in a direction to cancel the harmonic magnetic flux P1.

[0033] As a result, the value of the harmonic magnetic flux P1 coupled to the shaft 21 and the permanent magnets 22 is reduced, resulting in a reduction in the value of heat generated by the shaft 21 and the permanent magnets 22. The conductive element 23 generates heat when the eddy currents C are generated therein, but since the conductivity of the conductive element 23 is higher than the conductivity of the permanent magnet 22, the value of heat generated by the conductive element 23 is smaller than the value of heat that would be generated by the permanent magnet 22 if the harmonic magnetic flux were coupled to the permanent magnet 22.

[0034] As a result, the total value of heat generated by the rotor 2 is kept small. It should be noted that in Fig. 4 to Fig. 6 the eddy currents C flowing from the back side to the front side with respect to the paper plane are indicated with a black circle in a white circle, while the eddy currents C flowing from the front side to the back side of the paper plane are indicated with a cross in a white circle.

[0035] The rotor 2 according to the first embodiment will be explained below in comparison with the respective rotors according to a first comparative example and a second comparative example.

[0036] Fig. Fig. 5 is a partially enlarged view showing the rotor according to the first comparative example. It should be noted that Fig. 5 is a view showing a part of the rotor according to the first comparative example, the Fig. 4. In the rotor according to the first comparative example, the conductive member 23 is not provided, and therefore the holding member 24 directly overlaps the outer peripheral surface of the permanent magnet 22. All other configurations of the rotor according to the first comparative example are identical to the first embodiment.

[0037] In the rotor according to the first comparative example, the conductive member 23 does not exist, and therefore the harmonic magnetic flux P1 generated by the stator 3 is coupled to the permanent magnet 22 and the shaft 21 without being reduced by the conductive member 23. Consequently, the eddy currents generated in the permanent magnet 22 and the shaft 21 increase, and as a result, the permanent magnet 22 and the shaft 21 are more likely to generate heat.

[0038] Fig. Fig. 6 is a partially enlarged view showing the rotor according to the second comparative example. It should be noted that Fig. 6 is a view showing a part of the rotor according to the second comparative example, the Fig. 4. In the rotor according to the second comparative example, the conductive element 23 is not arranged on the outer periphery of the permanent magnet 22, and instead, the conductive element 23 is arranged between the outer peripheral surface of the shaft 21 and the permanent magnet 22. All other configurations of the rotor according to the second comparative example are identical to the first embodiment.

[0039] In the rotor according to the second comparative example, the conductive member 23 is arranged at a position farther from the stator 3 than the permanent magnet 22, and therefore the harmonic magnetic flux P1 generated by the stator 3 is coupled to the permanent magnet 22 without being reduced by the conductive member 23. As a result, the eddy currents generated in the permanent magnet 22 increase, and as a result, the permanent magnet 22 is more likely to generate heat.

[0040] It is therefore clear that in the rotors according to both the first and second comparative examples, the harmonic magnetic flux P1 is coupled to the permanent magnet 22 without being reduced by the conductive member 23, and as a result, the permanent magnet 22 is more likely to generate heat than in the rotor 2 according to the first embodiment.

[0041] Further, in the rotor 2 according to the first embodiment, the harmonic magnetic flux P1 generated by the stator 3 passes through the region 26 between the opposing portions of the conductive member 23 as it is. However, since the region 26 between the opposing portions is located within the circumferential direction range of the region 25 between the magnets where the permanent magnet 22 does not exist, the harmonic magnetic flux P1 is unlikely to be coupled to the permanent magnet 22, and therefore, heat generation by the permanent magnet 22 is suppressed.

[0042] In the rotary electric machine 1 and the rotor 2, as described above, the conductive member 23, whose conductivity is higher than that of the permanent magnet 22, surrounds the shaft 21 and the plurality of permanent magnets 22 as a whole, while the first opposing portion 231 and the second opposing portion 232 of the conductive member 23 are separated from each other in the circumferential direction.

[0043] Therefore, the conductive element 23 can be incorporated into the rotor 2 simply by winding the plate-shaped conductive element 23 around the shaft 21 and the respective permanent magnets 22 as a whole. Consequently, the shape of the conductive element 23 can be simplified, and the process of mounting the conductive element 23 to the rotor 2 can be performed easily.

[0044] As a result, the rotor 2 can be manufactured simply. Furthermore, the harmonic magnetic flux P1 generated by the stator 3 can be coupled to the conductive element 23 before reaching the permanent magnets 22, and therefore the harmonic magnetic flux P1 can be reduced. Consequently, the permanent magnets 22 are less likely to generate heat, and demagnetization of the permanent magnets 22 can be prevented.

[0045] Furthermore, the inter-opposing region 26 existing between the first opposing region 231 and the second opposing region 232 of the conductive member 23 is located only within the circumferential direction range of the inter-magnet region 25 located between adjacent permanent magnets 22.

[0046] Therefore, the probability that the harmonic magnetic flux P1 passing through the region 26 between the opposing areas will be coupled to the permanent magnet 22 is reduced. As a result, demagnetization of the permanent magnets 22 can be further prevented.

[0047] Furthermore, the probability that the harmonic magnetic flux P1 passes through the conductive member 23 can also be reduced by bringing the first opposing region 231 and the second opposing region 232 of the conductive member 23 into contact with each other; but this increases the contact resistance at the boundary between the first opposing region 231 and the second opposing region 232.

[0048] In this case, eddy currents flow through the boundary between the first opposing region 231 and the second opposing region 232, resulting in large eddy current losses, and as a result, the effect that the harmonic magnetic flux P1 is reduced by the magnetic flux generated by the eddy currents is deteriorated.

[0049] In addition, in this case, heat is more likely to be generated at the boundary between the first opposing region 231 and the second opposing region 232, and the heat generated at the boundary between the first opposing region 231 and the second opposing region 232 is easily transferred to the permanent magnets 22, resulting in an increase in the probability that the permanent magnets 22 are demagnetized.

[0050] However, in this embodiment, the first opposing portion 231 and the second opposing portion 232 of the conductive member 23 are separated from each other in the circumferential direction, and therefore, no contact resistance arises in the conductive member 23, and no heat is generated due to the contact resistance in the conductive member 23. As a result, in this embodiment, the demagnetization of the permanent magnets 22 can be even further suppressed.

[0051] Furthermore, there is no need to divide the conductive member 23 in the axial direction of the rotor 2, and therefore, a reduction in the length of an eddy current path in the axial direction of the rotor 2 can be prevented. Consequently, a reduction in the eddy currents generated in the conductive member 23 can be prevented, and as a result, a reduction in the effect of reducing the harmonic magnetic flux P1 can be prevented.

[0052] It should be noted that in the example described above, only one region 26 is formed between the opposing areas in the conductive element 23, but as in Fig. As shown in Figure 7, the region 26 between the opposing portions may also be formed in the conductive member 23 in a plurality of circumferentially spaced intervals. In this case, each region 26 between the opposing portions is located only within the circumferential range of the region 25 between the magnets.

[0053] In the case where the region 26 between the opposing portions in the conductive member 23 is formed in a plurality, the conductive member 23 has a plurality of conductive pieces, and the plurality of conductive pieces are spaced from each other in the circumferential direction across the regions 26 between the opposing portions so that the respective end portions of each conductive piece serve as the first opposing portion 231 and the second opposing portion 232.

[0054] In the Fig. 7, four regions 26 between the opposing areas are formed in the conductive member 23, and the regions 26 between the opposing areas are individually arranged within the respective circumferential direction areas of the four regions 25 between the magnets.

[0055] Furthermore, the Fig. In the example shown in Figure 7, four conductive pieces 233 are laminated onto the respective outer peripheral surfaces of the permanent magnets 22, so that the regions 26 exist between the opposing areas between adjacent conductive pieces 233. In this case, the conductive element 23 can be incorporated into the rotor 2 by simply adhering the conductive pieces 233, respectively, to the outer peripheral surfaces of the permanent magnets 22, and as a result, the rotor 2 can be manufactured even more easily.

[0056] Furthermore, in the example described above, the region 26 between the opposing portions is formed continuously over the entire region in the axial direction of the conductive element 23; however, the respective parts of the first opposing portion 231 and the second opposing portion 232 of the conductive element 23 may also be connected to each other via a coupling portion. In this case, the coupling portion has a higher conductivity than the permanent magnet 22.

[0057] The coupling portion may be formed by joining the respective parts of the first opposing portion 231 and the second opposing portion 232 directly to each other by welding, or by inserting a joining piece between the first opposing portion 231 and the second opposing portion 232 and joining the joining piece to the first and second opposing portions 231, 232 by welding.

[0058] As in Fig. 8, for example, in the case where the respective parts of the first opposing portion 231 and the second opposing portion 232 of the conductive member 23 are connected to each other via the coupling portion, the first opposing portion 231 and the second opposing portion 232 may be connected to each other via the coupling portions 234 only at the respective axial direction end portions of the conductive member 23, so that the space serving as the region 26 between the opposing portions remains as it is at an axial direction center position of the conductive member 23.

[0059] Thereby, the length of the paths of the eddy currents C passing through the two coupling portions 234 arranged at the respective axial direction end portions of the conductive member 23 can be increased in length, and as a result, the effect of reducing the harmonic magnetic flux P1 from the stator 3 by means of the magnetic flux generated by the eddy currents C can be improved.

[0060] Furthermore, in the above-described example, the axial dimension La of the conductive member 23 is set to be identical to the axial dimension Lm of the permanent magnet 22. Alternatively, the axial dimension La of the conductive member 23 may be made larger than the axial dimension Lm of the permanent magnet 22. This can lengthen the paths of the eddy currents C generated in the conductive member 23, and as a result, the effect of reducing the harmonic magnetic flux P1 can be further enhanced. Second embodiment

[0061] Fig. 9 is an enlarged sectional view showing main parts of a rotor for a rotary electric machine according to a second embodiment of the invention. Fig. Fig. 9 is a view showing a part of the rotor according to the second embodiment, the Fig. 3. The rotor 2 further includes a plurality of interpole elements 31 formed in the regions 25 between the magnets, respectively, and an electrical insulating layer 32 interposed between the conductive element 23 and the respective permanent magnets 22 and interpole elements 31.

[0062] Each of the interpole elements 31 is arranged in the axial direction of the rotor 2. Further, each interpole element 31 is fitted without gaps between the respective side surfaces of two adjacent permanent magnets 22. The region 26 between the opposing regions is located within a circumferential direction range of the interpole element 31. Further, no step is formed at the boundary between the outer peripheral surface of the interpole element 31 and the outer peripheral surface of the permanent magnet 22. In other words, the outer peripheral surface of the interpole element 31 is smoothly connected to the outer peripheral surface of the permanent magnet 22.

[0063] The conductivity of the element 31 between the poles is higher than the conductivity of the permanent magnet 22. The elements 31 between the poles can be formed from the identical material of the conductive element 23 or from a different material.

[0064] When a specific attraction force difference between the interpole member 31 and the permanent magnet 22 is large, shear stresses caused by the centrifugal force of the rotor 2 act on the conductive member 23 at a boundary portion between the interpole member 31 and the permanent magnet 22, and therefore, the specific attraction force difference between the interpole member 31 and the permanent magnet 22 is preferably as small as possible.

[0065] More preferably, the specific attraction force of the element 31 between the poles is equal to the specific attraction force of the permanent magnet 22. In this case, an iron-based alloy such as stainless steel, which has a small specific attraction force difference with the permanent magnet 22, is used as the material of the element 31 between the poles.

[0066] The electrically insulating layer 32 surrounds the shaft 21, the permanent magnets 22, and the interpole elements 31 as a whole, overlapping the respective outer peripheral surfaces of the permanent magnets 22 and the interpole elements 31. The conductive element 23 overlaps an outer peripheral surface of the electrically insulating layer 32. As a result, the conductive element 23 is electrically insulated from the permanent magnets 22 and the interpole elements 31 by the electrically insulating layer 32.

[0067] In this embodiment, when the harmonic magnetic flux P1 is generated by the stator 3, the harmonic magnetic flux P1 passing through the region 26 between the opposing sections is coupled to the interpole element 31. When the harmonic magnetic flux P1 is coupled to the interpole element 31, eddy currents are generated in the interpole element 31, and when the eddy currents are generated, the magnetic flux is generated in a direction that cancels the harmonic magnetic flux P1.

[0068] As a result, the harmonic magnetic flux P1 passing through the region 26 between the opposing sections is reduced before reaching the shaft 21 and the permanent magnets 22. All other configurations and operations are identical to the first embodiment.

[0069] In the rotary electric machine 1 and the rotor 2 constructed as described above, the interpole element 31 is formed in the region 25 between the magnets, and the conductivity of the interpole element 31 is set to be higher than the conductivity of the permanent magnet 22. Therefore, even if the harmonic magnetic flux P1 generated by the stator 3 passes through the region 26 between the opposing regions, the harmonic magnetic flux P1 passing through the region 26 between the opposing regions can be coupled to the interpole element 31, so that eddy currents are generated in the interpole element 31, and as a result, a magnetic flux is generated in a direction in which it cancels the harmonic magnetic flux P1.

[0070] As a result, the harmonic magnetic flux P1 from the element 31 between the poles and the conductive element 23 can be reduced, and as a result, demagnetization of the permanent magnets 22 can be further prevented.

[0071] Furthermore, the electrically insulating layer 32 is interposed between the conductive element 23 and the respective permanent magnets 22 and interpole elements 31. Therefore, the conductive element 23 can be electrically insulated from the interpole elements 31, preventing eddy currents from flowing between the conductive element 23 and the interpole elements 31. Consequently, eddy current losses and heat generation in the rotor 2 can be suppressed, and as a result, demagnetization of the permanent magnets 22 can be further suppressed.

[0072] Specifically, when the conductive element 23 touches the interpole element 31, the contact resistance at the boundary between the conductive element 23 and the interpole element 31 increases. In this case, when eddy currents flow through the boundary between the conductive element 23 and the interpole element 31, large eddy current losses occur, and as a result, the effect of reducing the harmonic magnetic flux P1 due to the magnetic flux generated by the eddy currents deteriorates.

[0073] Furthermore, in this case, heat is more likely to be generated at the boundary between the conductive member 23 and the interpole member 31, and the heat generated at the boundary between the conductive member 23 and the interpole member 31 is easily transferred to the permanent magnet 22, resulting in an increase in the probability of the permanent magnet 22 being demagnetized. However, in this embodiment, the electrically insulating layer 32 prevents eddy currents from flowing between the conductive member 23 and the interpole member 31, and therefore, eddy current loss and heat generation in the rotor 2 can be suppressed. As a result, demagnetization of the permanent magnets 22 can be further suppressed.

[0074] Note that, in the example described above, an adhesive layer for firmly adhering the conductive member 23 to the respective outer peripheral surfaces of the permanent magnets 22 and the interpole elements 31 may be used as the electrically insulating layer 32. An adhesive that offers superior electrical insulation performance, such as an epoxy resin-based adhesive or a silicon resin-based adhesive, is preferably used as the adhesive constituting the adhesive layer, but there are no particular limitations.

[0075] Furthermore, in the example described above, the electrically insulating layer 32 is preferably arranged over the entire area of the conductive element 23 in the axial direction of the rotor 2. More specifically, the axial dimension Li of the electrically insulating layer 32 is preferably equal to the axial dimension La of the conductive element 23, or in other words, it is preferable that the relationship Li = La is satisfied.

[0076] Furthermore, in the example described above, the shear stresses on the retaining element 24 steadily increase as the circumferential extent d1 of the region 26 between the opposing areas increases. Therefore, the circumferential extent d1 of the region 26 between the opposing areas is preferably as small as possible.

[0077] Therefore, to specify a target range for the circumferential extension d1 of the region 26 between the opposing regions, the relationship between a stress concentration factor of the stresses generated in the support member 24 and the circumferential extension d1 of the region 26 between the opposing regions is calculated through analysis. The stress concentration factor is a value obtained by dividing the maximum stress generated in a member by the average stress, and it is used as an index when evaluating fatigue strength.

[0078] In the analysis, carbon fiber reinforced plastic was used as the material for the support element 24, copper was used as the material for the conductive element 23, and stainless steel was used as the material for the interpole element 31. Furthermore, in the analysis, the rotational speed of the rotor 2 was set to 30,000 rpm, and the outer diameter of the rotor 2 was specified to approximately 100 mm.

[0079] Fig. Figure 10 is a graph showing the relationship between the stress concentration factor of the stresses generated in the holding element 24, which is Fig. 9, and the circumferential extent d1 of the region 26 between the opposing sections. To ensure sufficient fatigue strength in the retaining element 24, the stress concentration factor is preferably not greater than 1.4.

[0080] In the Fig. 10, the stress concentration factor of the retaining element 24 remains at or below 1.4 when the circumferential dimension d1 of the region 26 between the opposing areas is not greater than 5 mm. Therefore, in the example described above, the circumferential dimension d1 of the region 26 between the opposing areas is preferably not greater than 5 mm.

[0081] Furthermore, in the example described above, the respective side corner portions of the holding member 24 of the first opposing portion 231 and the second opposing portion 232 of the conductive member 23 may be chamfered. This can reduce the shear stresses exerted on the holding member 24 by the conductive member 23, and as a result, the holding member 24 can be prevented from breaking. Third embodiment

[0082] Fig. 11 is an enlarged sectional view showing main parts of a rotor for a rotary electric machine according to a third embodiment of the invention. Fig. 11 is a view showing a part of the rotor according to the third embodiment, the Fig. 3. The rotor 2 further comprises a filling element 45 formed in the region 26 between the opposing areas.

[0083] The filling member 45 is an electrical insulator. Furthermore, the filling member 45 is disposed in the region 26 between the opposing portions without any gaps. In this example, a resin-molded body is filled into the region 26 between the opposing portions as the filling member 45. No step is formed at the boundary between the outer peripheral surface of the filling member 45 and the outer peripheral surface of the conductive member 23. In other words, the outer peripheral surface of the filling member 45 is smoothly bonded to the outer peripheral surface of the conductive member 23. All other configurations and operations are identical to the second embodiment.

[0084] In the rotary electric machine 1 and the rotor 2 constructed as described above, the filler 45 is formed in the region 26 between the opposing portions, and therefore, the holding member 24 can be held by the filler 45 in the region 26 between the opposing portions. Consequently, the shear stresses acting on the holding member 24 at the positions of the first opposing portion 231 and the second opposing portion 232 of the conductive member 23 can be reduced, and as a result, the holding member 24 can be prevented from breaking.

[0085] Furthermore, the filling member 45 is an electrical insulator, and therefore, eddy currents can be more reliably prevented from flowing between the first opposing region 231 and the second opposing region 232. Consequently, eddy current losses in the conductive member 23 can be reduced, and as a result, demagnetization of the permanent magnets 22 can be more reliably prevented.

[0086] Note that there are no particular restrictions on the material of the filler member 45. However, if the specific attraction force difference between the filler member 45 and the conductive member 23 is large, the shear stress acting on the support member 24 may increase due to the difference in centrifugal forces generated when the rotor 2 rotates. Therefore, the specific attraction force difference between the filler member 45 and the conductive member 23 is preferably as small as possible, and more preferably, the specific attraction force of the filler member 45 is equal to the specific attraction force of the conductive member 23.

[0087] Furthermore, in the example described above, the configuration in which the filling member 45 is arranged in the region 26 between the opposing portions is applied to the rotor 2 according to the second embodiment, but the configuration in which the filling member 45 is arranged in the region 26 between the opposing portions can also be applied to the rotor 2 according to the first embodiment. Fourth embodiment

[0088] Fig. 12 is an enlarged sectional view showing main parts of a rotor for a rotary electric machine according to a fourth embodiment of the invention. Fig. 12 is a view showing a part of the rotor according to the fourth embodiment, the Fig. 3. The interpole element 31 formed in the intermagnetic region 25 corresponding to the circumferential position of the interopposed region 26 among the respective intermagnetic regions 25 includes an interpole element main body 311 and a protrusion portion 312 projecting radially outward from the interpole element main body 311 and penetrating the electrically insulating layer 32 to reach the interior of the interopposed region 26.

[0089] The interpole element main body 311 is fitted without a gap between the respective side surfaces of two adjacent permanent magnets 22. No step is formed at the boundary between the outer peripheral surface of the interpole element main body 311 and the outer peripheral surface of the permanent magnet 22. In other words, the outer peripheral surface of the interpole element main body 311 is smoothly connected to the outer peripheral surface of the permanent magnet 22.

[0090] The protrusion extent by which the protrusion portion 312 protrudes from the main body 311 of the interpole element is equal to the sum of the thickness extent of the electrical insulating layer 32 and the thickness extent of the conductive member 23. Further, a protrusion end surface of the protrusion portion 312 is in contact with an inner peripheral surface of the holding member 24.

[0091] Accordingly, the protrusion end surface of the protrusion portion 312 contacts the inner peripheral surface of the support member 24 on a hypothetical circle overlapping the outer peripheral surface of the conductive member 23 that contacts the support member 24. Consequently, the circumferential dimension of the protrusion portion 312—or, in other words, the width dimension d3 of the protrusion portion 312—is smaller than the circumferential dimension d1 of the region 26 between the opposing portions.

[0092] As a result, the protrusion portion 312 is removed from both the first opposing portion 231 and the second opposing portion 232 of the conductive member 23. In other words, small gaps g are formed in the circumferential direction between the protrusion portion 312 and the first opposing portion 231 and the second opposing portion 232, respectively. All other configurations and operations are identical to those of the second embodiment.

[0093] In the rotary electric machine 1 and the rotor 2 constructed as described above, the protrusion portion 312 projecting from the interpole element main body 311 formed in the region 25 between the magnets penetrates the electrically insulating layer 32 to reach the region 26 between the opposing portions and come into contact with the holding member 24. Therefore, the holding member 24 can be held by the protrusion portion 312 between the first protrusion portion 231 and the second protrusion portion 232 of the conductive member 23, enabling a reduction in the shear stresses acting on the holding member 24 from each of the first opposing portion 231 and the second opposing portion 232.

[0094] As a result, the holding member 24 can be prevented from breaking. Furthermore, by disposing the protrusion portion 312 in the region 26 between the opposing portions, the ratio of the harmonic magnetic flux P1 generated by the stator 3 passing through the region 26 between the opposing portions can be further reduced, and as a result, the demagnetization of the permanent magnets 22 can be further suppressed.

[0095] Furthermore, the protrusion portion 312 is spaced apart from both the first opposing portion 231 and the second opposing portion 232 of the conductive element 23, and therefore, eddy currents can be more reliably prevented from flowing between the conductive element 23 and the protrusion portion 312. As a result, eddy current losses in both the conductive element 23 and the element 31 between the poles can be reduced.

[0096] It should be noted that, in the example described above, the shear stresses acting on the holding member 24 from the first and second opposing portions 231, 232 steadily decrease as the circumferential direction extent of each of the gaps g formed between the conductive member 23 and the protrusion portion 312 decreases, but if the gap g is too small, the conductive member 23 and the protrusion portion 312 are more likely to come into contact with each other.

[0097] In order to ensure that the conductive member 23 and the protrusion portion 312 do not contact each other, the extent of the gap g is preferably set to be larger than the extent obtained by adding circumferential direction manufacturing errors of the protrusion portion 312 and circumferential direction manufacturing errors of the conductive member 23 together.

[0098] Furthermore, in the above-described example, the interpole element 31 having the interpole element main body 311 and the protrusion portion 312 is disposed in the intermagnetic region 25 of the rotor 2 according to the second embodiment, but the interpole element 31 having the interpole element main body 311 and the protrusion portion 312 may also be disposed in the intermagnetic region 25 of the rotor 2 according to the first embodiment, which does not have the electrical insulating layer 32.

[0099] In this case, the interpole element main body 311 is disposed in the region 25 between the magnets such that the protrusion portion 312 projecting from the interpole element main body 311 toward the region 26 between the opposing portions contacts an inner peripheral surface of the holding member 24. Further, in this case, the interpole element 31 is formed of an electrical insulator. Similarly, in this case, the shear stresses acting on the holding member 24 from the first opposing portion 231 and the second opposing portion 232 can be reduced, and as a result, the holding member 24 can be prevented from breaking. Fifth embodiment

[0100] Fig. 13 is an enlarged sectional view showing main parts of a rotor for a rotary electric machine according to a fifth embodiment of the invention. Fig. Fig. 13 is a view showing a part of the rotor according to the fifth embodiment, the Fig. 3. The rotor 2 further comprises a conductive layer 51 interposed between the electrical insulating layer 32 and the respective permanent magnets 22 and elements 31 between the poles.

[0101] The conductive layer 51 surrounds the shaft 21, the permanent magnets 22, and the interpole elements 31 as a whole. Furthermore, the conductive layer 51 overlaps the outer peripheral surfaces of the permanent magnets 22 and the interpole elements 31 over the entire circumferential periphery of the rotor 2. The conductive layer 51 has a higher conductivity than the permanent magnets 22. For example, an aluminum alloy, a copper alloy, or the like is used as a material for forming the conductive layer 51.

[0102] The electrically insulating layer 32 is interposed between the conductive layer 51 and the conductive element 23. As a result, the conductive element 23 is electrically insulated from the conductive layer 51 by the electrically insulating layer 32. The conductivity of the elements 31 between the poles is not particularly limited and can be set to any suitable value.

[0103] In this embodiment, when the harmonic magnetic flux P1 is generated by the stator 3, the harmonic magnetic flux P1 passing through the region 26 between the opposing portions is coupled to the conductive layer 51. When the harmonic magnetic flux P1 is coupled to the conductive layer 51, eddy currents are generated in the conductive layer 51, and when the eddy currents are generated, a magnetic flux is generated in a direction that cancels the harmonic magnetic flux P1.

[0104] As a result, the harmonic magnetic flux P1 passing through the region 26 between the opposing sections is reduced before reaching the shaft 21 and the permanent magnets 22. All other configurations and operations are identical to the second embodiment.

[0105] In the rotary electric machine 1 and the rotor 2 constructed as described above, the conductive layer 51, which has a higher conductivity than the permanent magnets 22, is interposed between the electrically insulating layer 32 and the respective permanent magnets 22 and interpole elements 31. Therefore, even if the harmonic magnetic flux P1 generated by the stator 3 passes through the region 26 between the opposing portions, the harmonic magnetic flux P1 passing through the region 26 between the opposing portions can be coupled to the conductive layer 51, so that a magnetic flux is generated in a direction in which the harmonic magnetic flux P1 is canceled, in response to the eddy currents generated in the conductive layer 51.Accordingly, the harmonic magnetic flux P1 can be reduced by means of the conductive layer and the conductive element 23, and as a result, demagnetization of the permanent magnets 22 can be further prevented.

[0106] Furthermore, the electrically insulating layer 32 is interposed between the conductive layer 51 and the conductive element 23. Therefore, the conductive element 23 can be electrically insulated from the conductive layer 51, preventing eddy currents from flowing between the conductive element 23 and the conductive layer 51. Consequently, eddy current losses and heat generation in the rotor 2 can be suppressed, and as a result, demagnetization of the permanent magnets 22 can be further suppressed.

[0107] It should be noted that in the example described above, if the thickness extension of the conductive layer 51 is excessively large, an enlarged magnetic gap is formed, and as a result, the loss in the stator 3 increases. On the other hand, if the thickness extension of the conductive layer 51 is excessively small, the resistance generated by the conductive layer 51 increases, which makes it difficult for the eddy currents to flow through the conductive layer 51, and as a result, the effect of canceling the harmonic magnetic flux P1 deteriorates.

[0108] When an aluminum alloy is used as the material for the conductive layer 51, a sufficient effect of canceling the harmonic magnetic flux P1 can be achieved without greatly affecting the magnetic gap by setting the thickness extension of the conductive layer 51 within a range of 0.2 mm to 0.5 mm.

[0109] In the example described above, a gap also serves as the region 26 between the opposing areas. However, similar to the third embodiment, the filling element 45 can also be arranged in the region 26 between the opposing areas. Sixth embodiment

[0110] Fig. 14 is a sectional view showing an electric rotary machine according to a sixth embodiment of the invention. The rotor 2 further includes a pair of ring members 61 formed on the respective axial-direction outer sides of the permanent magnets 22. The permanent magnets 22 are sandwiched between the pair of ring members 61 in the axial direction of the rotor 2. One ring member 61 contacts one end surface of each of the permanent magnets 22, and the other ring member 61 contacts the other end surface of each of the permanent magnets 22.

[0111] The pair of ring elements 61 are fitted to the outer peripheral surface of the shaft 21. Furthermore, the respective radial direction thicknesses of the pair of ring elements 61 are identical to the thickness dimension of the permanent magnet 22. The conductivity of each ring element 61 is not particularly limited and can be set to any suitable value.

[0112] The electrically insulating layer 32, the conductive member 23, and the holding member 24 each extend to positions covering the pair of ring members 61 in the axial direction of the rotor 2. Accordingly, at the axial direction position of each ring member 61, an outer peripheral surface of the ring member 61 is covered by the electrically insulating layer 32, the outer peripheral surface of the electrically insulating layer 32 is covered by the conductive member 23, and the outer peripheral surface of the conductive member 23 is covered by the holding member 24.

[0113] In other words, at the axial direction position of each ring element 61, the ring element 61 is arranged between the shaft 21 and the electrical insulating layer 32 in the radial direction of the rotor 2, while the conductive element 23 and the holding element 24 are laminated onto the outer peripheral surface of the electrical insulating layer 32 in succession toward the radial direction outside. Furthermore, in this example, as shown in Fig. 14: The respective configurations of the rotor 2 and the stator 3 are symmetrical about the orthogonal line B, which is orthogonal to the axis A at the axial direction center position of the stator core 4.

[0114] The relations of Lk ≥ La = Li > Lm and La > Ls are formed between the axial direction extent Li of the electrical insulating layer 32, the axial direction extent Lm of the permanent magnet 22, the axial direction extent La of the conductive member 23, the axial direction extent Lk of the holding member 24 and the axial direction extent Ls of the stator core 4.

[0115] When a current is supplied to the stator coils 5 by PWM control, the harmonic magnetic flux P1 derived from the carrier frequency is generated from the stator 3. At this time, a current is also supplied to the coil ends 5a located at the respective axial direction end portions of the stator 3, and therefore the harmonic magnetic flux P1 is also generated outside the axial direction region of the stator core 4.

[0116] Here, the conductive element 23 does not exist outside the axial direction region of the stator core 4, and therefore, when the axial direction dimension Ls of the stator core 4 is equal to the axial direction dimension La of the conductive element 23, or in other words, when Ls = La, the harmonic magnetic flux P1 generated outside the axial direction region of the stator core 4 is coupled to the shaft 21 without being reduced by the conductive element 23. Therefore, when Ls = La, large eddy current losses occur in the shaft 21 outside the axial direction region of the stator core 4.

[0117] However, in this embodiment, the conductive member 23 also exists outside the axial direction region of the stator core 4, and therefore, the harmonic magnetic flux P1 generated outside the axial direction region of the stator core 4 is coupled to the conductive member 23, so that eddy currents are generated in the conductive member 23. Consequently, the magnetic flux is generated in the direction in which the harmonic magnetic flux P1 is canceled, and as a result, the eddy current losses generated in the shaft 21 are reduced. All other configurations and operations are identical to those in the second embodiment.

[0118] In this rotary electric machine 1, the ring members 61 formed on the axial direction outer surfaces of the permanent magnets 22 are interposed between the shaft 21 and the electrically insulating layer 32, while the axial direction dimension Li of the electrically insulating layer 32, the axial direction dimension Lm of the permanent magnet 22, the axial direction dimension La of the conductive member 23, the axial direction dimension Lk of the holding member 24, and the axial direction dimension Ls of the stator core 4 are set to satisfy the following relations Lk ≥ La = Li > Lm and La > Ls.

[0119] Therefore, the harmonic magnetic flux P1 generated outside the axial direction region of the stator core 4 can be coupled to the conductive member 23. Consequently, the harmonic magnetic flux P1 can be reduced before reaching the shaft 21, even outside the axial direction region of the stator core 4, and therefore, the eddy current losses in the shaft 21 can be reduced. Consequently, heat generation by the rotor 2 can be further suppressed, and as a result, demagnetization of the permanent magnets 22 can be further suppressed.

[0120] In addition, when a gap is formed between the shaft 21 and the electrical insulating layer 32, the shear stress generated in the electrical insulating layer 32 and the conductive member 23 increases at the position where the axial direction end portions of the permanent magnets 22 contact the electrical insulating layer 32 due to the centrifugal force generated when the rotor 2 rotates. However, in this embodiment, the ring members 61 are interposed between the outer peripheral surface of the shaft 21 and the electrical insulating layer 32 outside the axial direction region of the stator core 4, and therefore, the shear stress generated in the electrical insulating layer 32 and the conductive member 23 can be reduced.

[0121] It should be noted that, in the example described above, the shear stresses generated in the electrically insulating layer 32 and the conductive element 23 steadily decrease as the specific attraction force difference between the ring element 61 and the permanent magnet 22 decreases. Therefore, the specific attraction force difference between the ring element 61 and the permanent magnet 22 is preferably as small as possible, and more preferably, the specific attraction force of the ring element 61 is equal to the specific attraction force of the permanent magnet 22.

[0122] Furthermore, the ring member may be formed by laminating a plurality of ring-shaped thin plates.

[0123] Furthermore, in the above-described example, the configuration in which the pair of ring members 61 are formed on the axial direction outer sides of the permanent magnets 22 is applied to the rotor 2 according to the second embodiment, but the configuration in which the pair of ring members 61 are formed on the axial direction outer sides of the permanent magnets 22 can also be applied to the rotors 2 according to the third to fifth embodiments. Seventh embodiment

[0124] Fig. 15 is a graph showing the relationship between the radial direction thickness of the conductive member 23 according to a seventh embodiment of the invention and the losses occurring in the rotor 2 when the inverter is operating. The rotor 2 according to this embodiment is configured identically to the rotor 2 according to the first embodiment, except that a setting range of the radial direction thickness t of the conductive member 23 is specified.

[0125] If the resistivity of the conductive element 23 is given as ρ, the permeability of the conductive element 23 as µ and the carrier angular frequency of the inverter for driving the electric rotary machine as ω c, then the penetration depth d of the conductive member 23 when the eddy currents generated in response to the harmonic magnetic flux of the carrier flow through the conductive member 23 is defined as shown in formula (1) below. [Math. 1] d=2ρωcμ

[0126] Fig. 15 shows the respective degrees of dependence on the radial direction thickness t of the conductive member 23 of the losses caused by the eddy currents generated in the conductive member 23, the losses caused by the eddy currents generated in the permanent magnets 22 and the shaft 21, that is, the elements on the inner peripheral side of the conductive member 23, and the losses of the rotor 2, that is, the sum of the above losses.

[0127] Here, it is assumed that the distance from the front surface of the teeth 42 of the stator 3 to the outer peripheral surface of the permanent magnets 22 is constant. Furthermore, in Fig. 15, the abscissa shows normalized values (t / d) obtained by normalizing the radial direction thickness t of the conductive element 23 with the penetration depth d, and the ordinate shows normalized values obtained by setting the losses of the rotor 2 in a case where the conductive element 23 does not exist (t = 0) to 1.

[0128] As in Fig. As shown in Figure 15, the losses in the parts on the inner peripheral side of the conductive element 23 steadily decrease as the radial direction thickness of the conductive element 23 increases. This is because as the radial direction thickness of the conductive element 23 increases, the cross-sectional area of the conductive element 23 increases, resulting in a decrease in its resistance. Consequently, the eddy currents flowing through the conductive element 23 become larger, and as a result, the harmonic magnetic flux of the carrier is canceled, so that the magnetic flux coupled to the elements on the inner peripheral side of the conductive element 23 decreases.

[0129] As from Fig. 15, the following applies. When t / d has a value of 0.1, the losses in the elements on the inner peripheral side of the conductive element 23 are not greater than half of the losses that occur when the conductive element 23 is omitted, and when t / d reaches a value of 1, the losses in the elements on the inner peripheral side of the conductive element 23 decrease to a value that is not greater than 1% of the losses that occur when the conductive element 23 is omitted.

[0130] However, as the radial thickness t of the conductive element 23 increases, the eddy currents through the conductive element 23 also increase, resulting in a corresponding increase in losses in the conductive element 23. However, as the radial thickness t of the conductive element 23 increases, the resistance of the conductive element 23 decreases, and therefore the losses of the conductive element 23 transition to a decreasing direction, approximately at the point where t / d exceeds a value of 0.15.

[0131] As the radial direction thickness t of the conductive member 23 further increases, the distance from the surface of the conductive member 23 to the teeth 42 of the stator 3 decreases, resulting in an increase in the variation of the magnetic flux density caused by a pulsation of the magnetic resistance, and as a result, the losses of the conductive member 23 gradually increase.

[0132] When t / d reaches a value of 2, the losses of the rotor 2 become identical to the losses that occur when the conductive element does not exist (t = 0), and when t / d exceeds the value of 2, the losses of the rotor 2 exceed the losses that occur when the conductive element does not exist (t = 0). Consequently, the losses of the rotor 2, that is, the sum of the losses of the conductive element 23 and the losses of the elements on the inner peripheral side of the conductive element 23, reach their minimum at t / d ≤ 1. In other words, the losses of the rotor 2 reach their minimum when the radial direction thickness t of the conductive element 23 is in a range of t / d ≤ 1.

[0133] The thickness t of the conductive member 23 according to this embodiment is set to satisfy the formula (2) shown below. [Math. 2] 0 <td≤2

[0134] In this embodiment, the thickness t of the conductive member 23 is set to satisfy formula (2), and therefore, the losses of the rotor 2 can be reduced compared to the case where the conductive member 23 does not exist. As a result, demagnetization of the permanent magnets 22 can be prevented.

[0135] Note that in this example, the radial direction thickness t of the conductive member 23 is set to satisfy the formula (2), but the range of the radial direction thickness t of the conductive member 23 can be further restricted by setting the radial direction thickness t of the conductive member 23 to satisfy the formula (3) shown below. [Math. 3] 0.1≤td≤1

[0136] By setting the radial direction thickness t of the conductive member 23 to satisfy the formula (3), the upper limit of t / d can be set to 1, and therefore, the losses of the rotor 2 can be reduced even compared to the case where the radial direction thickness t of the conductive member 23 is set to t / d ≤ 2, with the result that demagnetization of the permanent magnets 22 can be suppressed.

[0137] By setting the thickness t of the conductive element 23 to satisfy formula (3), the lower limit of t / d can be set to 0.1, and therefore, the losses of the elements on the inner peripheral side of the conductive element 23 can be reduced to no more than half of the losses that occur when the conductive element 23 does not exist. Consequently, the eddy current losses in the permanent magnets 22 can be reduced, and as a result, demagnetization of the permanent magnets 22 can be prevented.

[0138] It should be noted that in the first embodiment, each region 26 between the opposing portions is arranged only within the circumferential direction range of the region 25 between the magnets. As shown in Fig. 16, however, at least one of a plurality of the regions 26 may be arranged between the opposing areas within the circumferential direction range of the region 25 between the magnets.

[0139] In the case of rotor 2, which is Fig. 16, one of four regions 26 is arranged between the opposing areas within the circumferential direction range of the region 25 between the magnets, while the three remaining regions 26 are arranged between the opposing areas on the permanent magnets 22, rather than in the regions 25 between the magnets.

[0140] When this configuration is used, the harmonic magnetic component of the carrier coupled to the permanent magnets 22 can be canceled by the conductive member 23, unlike the case where all the regions 26 are formed between the opposing areas on the permanent magnets 22, and as a result, demagnetization of the permanent magnets 22 can be suppressed.

[0141] In addition, the configuration in which at least one of a plurality of the regions 26 is arranged between the opposing areas within the circumferential direction range of the region 25 between the magnets can be applied to each of the first to sixth embodiments.

[0142] Furthermore, in the embodiments described above, the respective configurations of the rotor 2 and the stator 3 are symmetrical with respect to the orthogonal line B, but the respective configurations of the rotor 2 and the stator 3 may also be asymmetrical with respect to the orthogonal line B.

[0143] The invention is not limited to the embodiments described above, and it may be subjected to various modifications based on the basic technical scope and teaching of the invention. List of reference symbols 1 electric rotary machine 2 rotors 3 Stator 4 Stator core 5 Stator coil 21 Shaft (rotor core) 22 permanent magnet 23 conductive element 24 Holding element 25 Region between the magnets 26 Region between the opposite areas 31 Element between the poles 32 electrical insulation layer 41 Filling element 51 conductive layer 61 ring element 231 first opposite area 232 second opposite area 311 Main body of the element between the poles 312 projection area

Claims

[1] Rotor for an electric rotary machine, comprising: a rotor core (21); a plurality of permanent magnets (22) provided at an outer peripheral portion of the rotor core (21) and arranged away from each other in the circumferential direction; a conductive element (23) surrounding the rotor core (21) and the plurality of permanent magnets (22) as a whole; and a holding element (24) which surrounds the rotor core (21), the plurality of permanent magnets (22) and the conductive element (23) as a whole, wherein the conductivity of the conductive element (23) is higher than the conductivity of the permanent magnet (22), the conductive element (23) has first and second opposing regions (231, 232) which are opposite to each other across a gap in the circumferential direction, and an axially extending inter-opposing region (26) existing between the first and second opposing regions (231, 232) is arranged within a circumferential direction range of an inter-magnet region (25) existing between permanent magnets (22) adjacent to each other in the circumferential direction and arranged where no permanent magnets are present, and when a radial direction thickness of the conductive element (23) is specified as t, the resistivity of the conductive element (23) is specified as ρ, the permeability of the conductive element (23) is specified as µ and the carrier angular frequency of the inverter used to drive the electric rotary machine (1) is specified as ω c is specified, and a penetration depth of the conductive element (23) is specified as d, then d is defined as follows: d=2ρωcμ , and a relationship that satisfies the following: 0 <td≤2 between t and d. [2] A rotor for an electric rotary machine according to claim 1, further comprising a ratio satisfying: 0.1≤td≤1 between t and d. [3] Rotor for an electric rotary machine, comprising: a rotor core (21); a plurality of permanent magnets (22) provided at an outer peripheral portion of the rotor core (21) and arranged away from each other in the circumferential direction; a conductive element (23) surrounding the rotor core (21) and the plurality of permanent magnets (22) as a whole; and a holding element (24) which surrounds the rotor core (21), the plurality of permanent magnets (22) and the conductive element (23) as a whole, wherein the conductivity of the conductive element (23) is higher than the conductivity of the permanent magnet (22), the conductive element (23) has first and second opposing regions (231, 232) which are opposite to each other across a gap in the circumferential direction, and an axially extending region (26) between the opposing portions, which exists between the first and second opposing portions (231, 232), is arranged within a circumferential direction range of a region (25) between the magnets, which exists between permanent magnets (22) which are adjacent to each other in the circumferential direction and is arranged where there are no permanent magnets (22), the rotor further comprises: an interpole element (31) provided in the region (25) between the magnets; and an electrical insulating layer (32) which is inserted between the conductive element (23) and the plurality of permanent magnets (22) and the element (31) between the poles. [4] A rotor for an electric rotary machine according to claim 3, wherein the interpole element (31) comprises: an interpole element main body (311) provided in the region (25) between the magnets; and a protrusion portion (312) penetrating the electrical insulating layer (32) from the interpole element main body (311) to reach the inside of the region (26) between the opposing portions and contacting the holding member (24). [5] A rotor for an electric rotary machine according to claim 4, wherein the protrusion portion (312) is eliminated from the first and second opposing portions (231, 232) of the conductive member (23). [6] Rotor for an electric rotary machine, comprising: a rotor core (21); a plurality of permanent magnets (22) provided at an outer peripheral portion of the rotor core (21) and arranged away from each other in the circumferential direction; a conductive element (23) surrounding the rotor core (21) and the plurality of permanent magnets (22) as a whole; and a holding element (24) which surrounds the rotor core (21), the plurality of permanent magnets (22) and the conductive element (23) as a whole, wherein the conductivity of the conductive element (23) is higher than the conductivity of the permanent magnet (22), the conductive element (23) has first and second opposing regions (231, 232) which are opposite to each other across a gap in the circumferential direction, and an axially extending region (26) between the opposing portions, which exists between the first and second opposing portions (231, 232), is arranged within a circumferential direction range of a region (25) between the magnets, which exists between permanent magnets (22) which are adjacent to each other in the circumferential direction and is arranged where there are no permanent magnets (22), the rotor further comprises: an interpole element (31) provided in the region (25) between the magnets; and an electrical insulating layer (32) which is inserted between the conductive element (23) and the plurality of permanent magnets (22) and the element (31) between the poles; and a conductive layer (51) which is inserted between the electrical insulating layer (32) and the plurality of permanent magnets and the element (31) between the poles, wherein the conductivity of the conductive layer (51) is higher than the conductivity of the permanent magnet (22). [7] A rotor for an electric rotary machine according to claim 3 or 6, further comprising a filling member (41) provided in the region (26) between the opposing portions, the filling member (41) being an electrical insulator. [8] A rotor for an electric rotary machine according to claim 1 or 2, further comprising an interpole member (31) provided in the region (25) between the magnets, the interpole member (31) comprising: an interpole member main body (311) provided in the region (25) between the magnets; and a protrusion portion (312) protruding from the interpole member main body (311) toward the region (26) between the opposing portions and contacting the holding member (24). [9] Electric rotary machine comprising: the rotor (2) according to one of claims 3 to 7; and a stator (3) which surrounds the rotor (2) via a radial direction gap. wherein the rotor (2) has a ring element (61) provided on an axial direction outer side of the permanent magnets (22), the ring element (61) is joined between the rotor core (21) and the electrical insulating layer (32), the stator (3) has a stator core (4), and a stator coil (5) provided on the stator core (4), the stator coil (5) has a coil end (5a) which protrudes from the stator core (4) in the axial direction, and when an axial dimension of the stator core (4) is specified as Ls, an axial dimension of the permanent magnet (22) is specified as Lm, an axial dimension of the conductive element (23) is specified as La, an axial dimension of the electrical insulating layer (32) is specified as Li, and an axial dimension of the holding element (24) is specified as Lk, the following relationships are obtained: Lk ≥ La = Li > Lm and La > Ls. [10] Electric rotary machine comprising: the rotor (2) according to one of claims 1 to 8; and a stator (3) which surrounds the rotor (2) via a radial direction gap.

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