Rotor of rotary electric machine

Abstract

To provide a rotor of a rotary electric machine capable of relaxing stress due to tightening allowance while cooling a rotor core well and suppressing reduction in the tightening allowance due to centrifugal force during high-speed rotation.SOLUTION: A rotor of a rotary electric machine includes: a plurality of refrigerant holes formed in a shaft at intervals in a circumferential direction so as to communicate with a shaft center hole; a plurality of refrigerant passages formed in a rotor core at intervals in the circumferential direction so as to extend in a shaft direction on a radially outer side of a core center hole; a plurality of communication passages formed in the rotor core at intervals in the circumferential direction so as to communicate with the corresponding refrigerant holes and communicate with the corresponding refrigerant passages at two different positions in the shaft direction; and a plurality of stress relaxation slots formed in the rotor core at intervals in the circumferential direction so as to surround the core center hole on a radially inner side of the plurality of refrigerant passages without interfering with the plurality of communication passages.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a rotor for a rotating electric machine that includes a hollow shaft and an annular rotor core fixed to the shaft by an interference fit. [Background technology]

[0002] A rotor for a rotating electric machine is known, which includes a shaft having a refrigerant passage and a refrigerant supply port, a rotor core formed by stacking steel plates and fixed to the shaft, and magnets housed within the rotor core so as to extend in the axial direction (see, for example, Patent Document 1). The rotor core of this rotor has a first flow passage extending along the magnet near the magnet, and a second flow passage connecting the refrigerant supply port of the shaft to the first flow passage. The second flow passage is formed symmetrically in the radial direction of the rotor core by second slits formed in multiple steel plates that constitute the axial central region of the rotor core. The first and second flow passages merge in the axial central region of the rotor core to form a refrigerant flow passage. This rotor for a rotating electric machine can supply a coolant at a lower temperature to the periphery of the magnet, where the temperature increases, while suppressing a decrease in strength of the steel plates due to the formation of the slits. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-176235 Summary of the Invention [Problem to be solved by the invention]

[0004] In a rotor in which a rotor core including the above-described first and second flow paths is fixed to a hollow shaft by an interference fit, it is necessary to alleviate stress due to interference while suppressing a decrease in interference due to centrifugal force at high rotation speeds. However, Patent Document 1 does not disclose or suggest any measures for alleviating stress due to interference or suppressing a decrease in interference due to centrifugal force at high rotation speeds.

[0005] Therefore, the main object of the present disclosure is to provide a rotor for a rotating electric machine that can effectively cool the rotor core while alleviating stress due to interference and suppressing a reduction in interference due to centrifugal force at high rotation speeds. [Means for solving the problem]

[0006] The rotor of a rotating electric machine disclosed herein includes a hollow shaft and an annular rotor core fixed to the shaft by an interference fit, and includes a plurality of refrigerant holes formed in the shaft at intervals along the circumferential direction so as to each communicate with a shaft center hole of the shaft, a plurality of refrigerant passages formed in the rotor core at intervals along the circumferential direction so as to each extend in the axial direction radially outside the core center hole of the rotor core, a plurality of communicating passages formed in the rotor core at intervals along the circumferential direction so as to each communicate with a corresponding refrigerant hole and to communicate with corresponding refrigerant passages at two different locations along the axial direction, and a plurality of stress relief slots formed in the rotor core at intervals along the circumferential direction so as to surround the core center hole radially inside the plurality of refrigerant passages without interfering with the plurality of communicating passages.

[0007] The rotor for a rotating electric machine disclosed herein includes a hollow shaft and an annular rotor core fixed to the shaft by an interference fit. The rotor core includes a plurality of refrigerant passages, a plurality of communicating passages, and a plurality of stress relief slots. The plurality of refrigerant passages are formed at intervals in the circumferential direction in the rotor core so as to extend axially radially outward of a core center hole of the rotor core. The plurality of communicating passages are formed at intervals in the circumferential direction in the rotor core so as to communicate with corresponding refrigerant holes formed in the shaft and to communicate with corresponding refrigerant passages at two different locations in the axial direction. This allows refrigerant supplied to the shaft center hole of the shaft to be supplied to each refrigerant passage via the plurality of refrigerant holes and the plurality of communicating passages by centrifugal force, thereby efficiently cooling the rotor core. Furthermore, the plurality of stress relief slots are formed at intervals in the circumferential direction in the rotor core so as to surround the core center hole radially inward of the plurality of refrigerant passages without interfering with the plurality of communicating passages. This reduces the stress generated around the rotor core center hole due to the interference fit between the shaft and the rotor core, and also reduces the centrifugal force acting on the radially inner portion of each stress relief slot of the rotating rotor core. As a result, the rotor for a rotating electric machine disclosed herein can effectively cool the rotor core, relieve stress due to interference, and suppress a reduction in interference due to centrifugal force at high rotation speeds.

[0008] Furthermore, the plurality of refrigerant holes may be formed at intervals in the circumferential direction in a central region of the shaft in the axial direction, and the plurality of communicating passages may be formed at intervals in the circumferential direction in the central region of the rotor core in the axial direction, and the communicating passages may include an inner communicating portion communicating with the refrigerant holes, a pair of outer communicating portions formed at intervals in the axial direction so as to communicate with each of the refrigerant passages, and a pair of intermediate communicating portions formed at intervals in the axial direction so as to communicate with a corresponding one of the inner communicating portion and the pair of outer communicating portions, and the plurality of stress relief slots may include a plurality of first slots formed radially outward of the inner communicating portions of the plurality of communicating passages, a plurality of second slots formed circumferentially between the intermediate communicating portions of the plurality of communicating passages, and a plurality of third slots formed radially inward of the outer communicating portions of the plurality of communicating passages.

[0009] This makes it possible to form the multiple communication passages and the multiple stress relief slots in the rotor core without interfering with each other, and to smoothly supply refrigerant to each refrigerant passage via the multiple communication passages.

[0010] Furthermore, the rotor core may include a plurality of core plates stacked in the axial direction, and the plurality of core plates may include a plurality of first core plates including inner slits that define the inner communicating portion and first slits that define the first slots, a plurality of second core plates including intermediate slits that define the intermediate communicating portion and second slits that define the second slots, a plurality of third core plates including outer slits that define the outer communicating portion and third slits that define the third slots, and a fourth core plate including slits that define the refrigerant passages and fourth slits that define the stress relief slots, and the plurality of second core plates may be stacked on both axial sides of the plurality of first core plates, and the plurality of third core plates may be stacked on the plurality of second core plates from both axial sides of the plurality of first core plates, and the plurality of fourth core plates may be stacked on the plurality of third core plates from both axial sides of the plurality of first core plates.

[0011] This makes it possible to form a plurality of refrigerant passages, a plurality of communication passages, and a plurality of stress relief slots in the rotor core while ensuring good assembly of the rotor. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram showing a rotor of a rotating electric machine according to the present disclosure; [Figure 2] 1 is an enlarged cross-sectional view showing a rotor of a rotating electric machine according to the present disclosure; [Figure 3] 2 is a plan view showing a first core plate that forms a rotor core of a rotor of a rotating electric machine according to the present disclosure. FIG. [Figure 4] 3 is a plan view showing a second core plate that forms a rotor core of a rotor of a rotating electric machine according to the present disclosure. FIG. [Figure 5] 4 is a plan view showing a third core plate that forms a rotor core of a rotor of a rotating electric machine according to the present disclosure. FIG. [Figure 6]10 is a plan view showing a fourth core plate that forms a rotor core of a rotor of a rotating electric machine according to the present disclosure. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, embodiments of the present disclosure will be described with reference to the drawings.

[0014] Fig. 1 is a schematic diagram showing a rotor 1 of a rotating electric machine according to the present disclosure, and Fig. 2 is an enlarged cross-sectional view of a main portion of the rotor 1. The rotor 1 shown in these drawings is a so-called interior permanent magnet (IPM) rotor that, together with a stator (not shown), constitutes a rotating electric machine (e.g., a three-phase AC motor). As shown, the rotor 1 includes a rotor shaft 2, a rotor core 3 fixed to the rotor shaft 2 by an interference fit such as shrink fitting or press fitting, and a plurality of permanent magnets 4 embedded in the rotor core 3 so as to form a plurality of magnetic poles.

[0015] The rotor shaft 2 is hollow and made of metal, and is interference-fitted into the core center hole 3h of the rotor core 3 so that an expanded diameter portion 2e, which expands radially outward from the outer circumferential surface, abuts against one end face of the rotor core 3. A cooling medium (e.g., hydraulic oil such as ATF) is supplied to the shaft center hole 2h of the rotor shaft 2 from a pump (not shown). A plurality of refrigerant holes 2r (e.g., eight in this embodiment) are formed in a central region in the longitudinal direction of the rotor shaft 2, spaced apart in the circumferential direction. Each refrigerant hole 2r communicates with the shaft center hole 2h of the rotor shaft 2 and opens at the outer circumferential surface of the rotor shaft 2.

[0016] As shown in FIG. 2, the rotor core 3 is formed by stacking a plurality of first core plates 31, second core plates 32, third core plates 33, and fourth core plates 34 in the axial direction, and includes a plurality of refrigerant passages 35 and a plurality of communication passages 36. The plurality of refrigerant passages 35 are formed at intervals in the circumferential direction of the rotor core 3 so as to extend axially along the corresponding permanent magnets 4 radially outside the core center hole 3h. Each refrigerant passage 35 extends from a central region of the rotor core 3 in the axial direction toward a corresponding end face of the rotor core 3 and opens at the corresponding end face. The plurality of communication passages 36 are formed at intervals in the circumferential direction in the central region of the rotor core 3 in the axial direction. Each communication passage 36 includes a single inner communication portion 36i, a pair (two) outer communication portions 36o, and a pair (two) middle communication portions 36m, and extends in a stepped manner from the core center hole 3h side of the rotor core 3 toward the outer periphery, as shown in FIGS. 1 and 2.

[0017] The first, second, third, and fourth core plates 31, 32, 33, and 34 are all formed into annular shapes from electromagnetic steel sheets by, for example, press working. As shown in Fig. 2, in this embodiment, a plurality of second core plates 32 are stacked on both axial sides of the plurality of first core plates 31. Furthermore, a plurality of third core plates 33 are stacked on the plurality of second core plates 32 from both axial sides of the plurality of first core plates 31. Then, a plurality of fourth core plates 34 are stacked on the plurality of third core plates 33 from both axial sides of the plurality of first core plates 31.

[0018] As shown in Fig. 3, the first core plate 31 includes a central hole 31h, multiple magnet slits 31a, multiple inner slits 31i, multiple slits 31x, and multiple first stress relief slits 311. The multiple magnet slits 31a are arranged in pairs at predetermined intervals (45° intervals in this embodiment), and two magnet slits 31a forming a pair are formed so as to move away from each other (to form a substantially V-shape) from the center toward the outer periphery of the first core plate 31. The multiple inner slits 31i are arranged at intervals (equally spaced) in the circumferential direction on the inner periphery of the first core plate 31 so as to communicate (open) with the central hole 31h. The multiple slits 31x are arranged at intervals (equally spaced) in the circumferential direction so as to be located radially outward of the corresponding inner slits 31i. The multiple first stress relaxation slits 311 are arranged circumferentially at intervals (equally spaced) between the inner slits 31i and the slits 31x in the radial direction, so that each is located radially outside the portion between the inner slits 31i adjacent to each other in the circumferential direction.

[0019] As shown in FIG. 4, the second core plate 32 includes a central hole 32h, multiple magnet slits 32a, multiple intermediate slits 32m, multiple slits 32y, and multiple second stress relief slits 322. The multiple magnet slits 32a are arranged in pairs at predetermined intervals (45° intervals in this embodiment), and two pairs of magnet slits 32a are formed so that they move away from each other (forming a substantially V-shape) from the center toward the outer periphery of the second core plate 32. The multiple intermediate slits 32m are arranged at regular intervals in the circumferential direction on the inner periphery of the second core plate 32 so as to partially overlap with the corresponding inner slits 31i of the first core plate 31 when viewed in the axial direction, without communicating (opening) with the central hole 32h. The multiple slits 32y are arranged at regular intervals in the circumferential direction radially outward of the multiple intermediate slits 32m. The second stress relaxation slits 322 are arranged radially inward of the slits 32y at intervals (equally spaced) in the circumferential direction so as to be located between the intermediate slits 32m adjacent in the circumferential direction.

[0020] As shown in FIG. 5, the third core plate 33 includes a central hole 33h, multiple magnet slits 33a, multiple outer slits 33o, and multiple third stress relief slits 333. The multiple magnet slits 33a are arranged in pairs at predetermined intervals (45° intervals in this embodiment), and each pair of magnet slits 33a is formed so as to separate from each other (forming a substantially V-shape) as it moves from the center to the outer periphery of the third core plate 33. The multiple outer slits 33o are arranged radially inward of the multiple magnet slits 33a at intervals (equally spaced) in the circumferential direction so as to partially overlap with the corresponding intermediate slits 32m of the third core plate 33 when viewed in the axial direction. The multiple third stress relief slits 333 are arranged radially inward of the portions between adjacent outer slits 33o at intervals (equally spaced) in the circumferential direction along the central hole 33h.

[0021] As shown in FIG. 6, the fourth core plate 34 includes a central hole 34h, multiple magnet slits 34a, multiple slits 34z, and multiple fourth stress relief slits 344. The multiple magnet slits 34a are arranged in pairs at predetermined intervals (45° intervals in this embodiment), and two magnet slits 34a in a pair are formed so as to separate from each other (to form a substantially V-shape) as they move from the center to the outer periphery of the fourth core plate 34. The multiple slits 34z are arranged radially inward of the multiple magnet slits 34a at intervals (equally spaced) in the circumferential direction so as to at least partially overlap with the corresponding outer slits 33o of the third core plate 33 when viewed in the axial direction. The multiple fourth stress relief slits 344 are arranged at intervals (equally spaced) in the circumferential direction along the central hole 34h.

[0022] When the first, second, third, and fourth core plates 31, 32, 33, and 34 are stacked in the axial direction, the center holes 31h, 32h, 33h, and 34h define the core center hole 3h of the rotor core 3. When the first, second, third, and fourth core plates 31, 32, 33, and 34 are stacked in the axial direction, the overlapping magnet slits 31a, 32a, 33a, and 34a define magnet holding portions that hold the permanent magnets 4.

[0023] Furthermore, when a plurality of first core plates 31 are stacked in the axial direction, the overlapping inner slits 31i define inner communicating portions 36i of the communicating passages 36, and the overlapping slits 31x define slots 36x (see FIG. 2) located radially outward of the inner communicating portions 36i. Furthermore, when a plurality of second core plates 32 are stacked in the axial direction, the overlapping intermediate slits 32m define intermediate communicating portions 36m of the communicating passages 36, and the overlapping slits 32y define slots 36y (see FIG. 2) located radially outward of the intermediate communicating portions 36m. Furthermore, when a plurality of third core plates 33 are stacked in the axial direction, the overlapping outer slits 33o define outer communicating portions 36o of the communicating passages 36, and when a plurality of fourth core plates 34 are stacked in the axial direction, the overlapping slits 34z define refrigerant passages 35.

[0024] As shown in FIG. 2 , the inner communication portion 36i of each communication passage 36 communicates with the corresponding refrigerant hole 2r. The pair of outer communication portions 36o of each communication passage 36 communicate with the corresponding refrigerant passage 35. The pair of intermediate communication portions 36m of each communication passage 36 communicate with the inner communication portion 36i and a corresponding one of the pair of outer communication portions 36o. As a result, each communication passage 36 communicates with the corresponding refrigerant hole 2r formed in the rotor shaft 2 and with the corresponding refrigerant passage 35 at two different locations in the axial direction of the rotor shaft 2. The pair of outer communication portions 36o communicate with each other via slots 36x formed radially outward of the inner communication portion 36i and slots 36y formed radially outward of each intermediate communication portion 36m.

[0025] Furthermore, when multiple first core plates 31 are stacked in the axial direction, the overlapping first stress relaxation slits 311 define first stress relaxation slots 301 radially outward from the portions between circumferentially adjacent inner communicating portions 36i and radially inward from the multiple refrigerant passages 35. When multiple second core plates 32 are stacked in the axial direction, the overlapping second stress relaxation slits 322 define second stress relaxation slots 302 between circumferentially adjacent middle communicating portions 36m. When multiple third core plates 33 are stacked in the axial direction, the overlapping third stress relaxation slits 333 define third stress relaxation slots 303 radially inward from the portions between circumferentially adjacent outer communicating portions 36o. Furthermore, when multiple fourth core plates 34 are stacked in the axial direction, the overlapping fourth stress relaxation slits 344 define multiple fourth stress relaxation slots 304 that are aligned circumferentially along the core center hole 3h. As a result, the rotor core 3 is formed with multiple first, second, third, and fourth stress relaxation slots 301-304 spaced apart in the circumferential direction so as to surround the core center hole 3h radially inside the multiple refrigerant passages 35 without interfering with the multiple communicating passages 36.

[0026] As described above, the rotor 1 of the rotating electric machine includes the hollow rotor shaft 2 and the annular rotor core 3 fixed to the rotor shaft 2 by interference fit. The rotor core 3 includes a plurality of refrigerant passages 35 and a plurality of communicating passages 36. The plurality of refrigerant passages 35 are formed at intervals in the circumferential direction in the rotor core 3 so as to extend in the axial direction radially outside the core center hole 3h of the rotor core 3. The plurality of communicating passages 36 are also formed at intervals in the circumferential direction in the rotor core 3 so as to communicate with corresponding refrigerant holes 2r formed in the rotor shaft 2 and to communicate with corresponding refrigerant passages 35 at two different locations in the axial direction.

[0027] As a result, when the rotor 1 rotates, the cooling medium supplied to the shaft center hole 2h of the rotor shaft 2 flows through the multiple refrigerant holes 2r into the inner communicating portions 36i of each communicating passage 36. The lubricating cooling medium that flows into each inner communicating portion 36i flows into the corresponding refrigerant passage 35 and slots 36x, 36y via a pair of intermediate communicating portions 36m and a pair of outer communicating portions 36o. As a result, the cooling medium flowing through the multiple refrigerant passages 35 effectively cools each permanent magnet 4 and the entire rotor core 3. The cooling medium absorbs heat from the rotor core 3, flows out through the openings of each refrigerant passage 35 formed on the end face of the rotor core 3, and is scattered radially outward by centrifugal force. The cooling medium that has scattered outside the rotor core 3 is collected within the case of the rotating electrical machine and cooled in a cooler (not shown) before being supplied again to the rotor core 3 by the pump.

[0028] Furthermore, the rotor core 3 includes a plurality of first, second, third, and fourth stress relief slots 301-304. The first, second, third, and fourth stress relief slots 301-304 are spaced apart circumferentially so as to surround the core center hole 3h radially inward of the plurality of refrigerant passages 35 without interfering with the plurality of communicating passages 36. This reduces stress generated around the core center hole 3h of the rotor core 3 due to the interference fit between the rotor shaft 2 and the rotor core 3, and also reduces centrifugal force acting on the portions of the rotating rotor core 3 radially inward of the first, second, third, and fourth stress relief slots 301-304. As a result, the rotor 1 can effectively cool the rotor core 3, relieve stress due to interference, and suppress a reduction in interference due to centrifugal force at high rotation speeds.

[0029] In the rotor 1, the refrigerant holes 2r are formed at intervals in the circumferential direction in an axial central region of the rotor shaft 2, and the communicating passages 36 are formed at intervals in the axial central region of the rotor core 3. Each communicating passage 36 includes an inner communicating portion 36i communicating with the corresponding refrigerant hole 2r, a pair of outer communicating portions 36o formed at an axial interval so as to communicate with the corresponding refrigerant passage 35, and a pair of middle communicating portions 36m formed at an axial interval so as to communicate with the corresponding one of the inner communicating portion 36i and the pair of outer communicating portions 36o. The first stress relaxation slots 301 are formed radially outward of the inner communicating portions 36i of the communicating passages 36, the second stress relaxation slots 302 are formed circumferentially between the middle communicating portions 36m of the communicating passages 36, and the third stress relaxation slots 303 are formed radially inward of the outer communicating portions 36o of the communicating passages 36. This makes it possible to form the multiple communicating passages 36 and the first, second, and third stress relief slots 301-303 in the rotor core 3 without interfering with each other, and to smoothly supply refrigerant to each refrigerant passage 35 via the multiple communicating passages 36.

[0030] Furthermore, the rotor core 3 is formed by stacking a plurality of first core plates 31, second core plates 32, third core plates 33, and fourth core plates 34 in the axial direction. That is, a plurality of second core plates 32 are stacked on both axial sides of the plurality of first core plates 31, and a plurality of third core plates 33 are stacked on the plurality of second core plates 32 from both axial sides of the plurality of first core plates 31. Furthermore, a plurality of fourth core plates 34 are stacked on the plurality of third core plates 33 from both axial sides of the plurality of first core plates 31. Furthermore, the first core plate 31 includes inner slits 31i that define the inner communicating portion 36i and first stress relaxation slits 311 that define the first stress relaxation slots 301, and the second core plate 32 includes intermediate slits 32m that define the intermediate communicating portion 36m and second stress relaxation slits 322 that define the second stress relaxation slots 302. Furthermore, the third core plate 33 includes an outer slit 33o that defines the outer communicating portion 36o and a third stress relaxation slit 333 that defines the third stress relaxation slot 303, and the fourth core plate 34 includes a slit 34z that defines the refrigerant passage 35 and a fourth stress relaxation slit 344 that defines the fourth stress relaxation slot 304. This makes it possible to form the multiple refrigerant passages 35, the multiple communicating passages 36, and the multiple first, second, third, and fourth stress relaxation slots 301-304 in the rotor core 3 while ensuring good assembly of the rotor 1.

[0031] It goes without saying that the cross-sectional shapes of the inner slits 31i and first stress relaxation slits 311 of the first core plate 31, the intermediate slits 32m and second stress relaxation slits 322 of the second core plate 32, the outer slits 33o and third stress relaxation slits 333 of the third core plate 33, and the slits 34z and fourth stress relaxation slits 344 of the fourth core plate 34 are not limited to those shown in Figures 3 to 6, and any cross-sectional shape can be adopted depending on the specifications of the rotor core 3, etc.

[0032] Furthermore, the invention of the present disclosure is not limited to the above-described embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment is merely one specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0033] The presently disclosed invention can be used in the manufacturing industry of rotating electrical machines, etc. [Explanation of symbols]

[0034] 1 rotor, 2 rotor shaft, 2h shaft center hole, 2r refrigerant hole, 3 rotor core, 3h core center hole, 301 first stress relief slot, 302 second stress relief slot, 303 third stress relief slot, 304 fourth stress relief slot, 31 first core plate, 31h center hole, 31i inner slit, 31x slit, 311 first stress relief slit, 32 second core plate, 32h center hole, 32m intermediate slit, 32y slit, 322 second stress relief slit, 33 third core plate, 33h center hole, 33o outer slit, 333 third stress relief slit, 34 fourth core plate, 34h center hole, 34z slit, 344 fourth stress relief slit, 35 refrigerant passage, 36 communication passage, 36i inner communication portion, 36m intermediate communication portion, 36o Outer communication part, 36x, 36y slot.

Claims

1. A rotor for a rotating electric machine includes a hollow shaft and an annular rotor core fixed to the shaft by interference fit, a plurality of refrigerant holes formed at intervals in the circumferential direction of the shaft so as to communicate with a shaft center hole of the shaft; a plurality of refrigerant passages formed in the rotor core at intervals in the circumferential direction so as to extend in the axial direction radially outward from a core center hole of the rotor core; a plurality of communication passages formed in the rotor core at intervals in the circumferential direction, each of which communicates with a corresponding one of the refrigerant holes and communicates with a corresponding one of the refrigerant passages at two different positions in the axial direction; a plurality of stress relief slots formed at intervals in the circumferential direction in the rotor core so as to surround the core center hole radially inward of the plurality of refrigerant passages without interfering with the plurality of communication passages; A rotor for a rotating electric machine comprising:

2. 2. The rotor for a rotating electric machine according to claim 1, the plurality of refrigerant holes are formed at intervals in a circumferential direction in a central region in an axial direction of the shaft, the plurality of communication passages are formed at intervals in the circumferential direction in a central region in the axial direction of the rotor core, the communication passage includes an inner communication portion communicating with the refrigerant hole, a pair of outer communication portions formed at intervals in the axial direction so as to communicate with the refrigerant passages, respectively, and a pair of intermediate communication portions formed at intervals in the axial direction so as to communicate with a corresponding one of the inner communication portion and the pair of outer communication portions, The plurality of stress relief slots include a plurality of first slots formed radially outside the inner communicating portions of the plurality of communicating passages, a plurality of second slots formed circumferentially between the intermediate communicating portions of the plurality of communicating passages, a plurality of third slots formed radially inside the outer communicating portions of the plurality of communicating passages, and a plurality of fourth slots formed so as to be aligned circumferentially along the core center hole outside the central region of the rotor core.

3. 3. The rotor for a rotating electric machine according to claim 2, the rotor core includes a plurality of core plates stacked in the axial direction, The plurality of core plates are a plurality of first core plates including inner slits defining the inner communication portions and first slits defining the first slots; a plurality of second core plates including intermediate slits that define the intermediate communicating portions and second slits that define the second slots; a plurality of third core plates including outer slits that define the outer communicating portions and third slits that define the third slots; a fourth core plate including a slit defining the refrigerant passage and a fourth slit defining the fourth slot; The plurality of second core plates are stacked on both sides of the plurality of first core plates in the axial direction, The third core plates are stacked on the second core plates from both axial sides of the first core plates, A rotor for a rotating electric machine, in which the plurality of fourth core plates are stacked on the plurality of third core plates from both axial sides of the plurality of first core plates.

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