Rotary electric machine

Abstract

This rotary electric machine makes it possible to cool a rotor housed in a case. The rotary electric machine comprises: a first passage formed in a rotor core of the rotor and allowing a first space on one end side of the rotor core and a second space on the other end side inside the rotary electric machine to communicate with each other; and a second passage provided radially outside the first passage and allowing the first space and the second space to communicate with each other. The rotary electric machine comprises a fan that rotates together with the rotor, causes a gas in the first space to flow through the first passage, the second space, and the second passage in this order, and circulates the gas to the first space. The rotary electric machine comprises a guide surface that is provided on a first surface facing one end of the rotor core in the case and guides the gas from the second passage to the first passage. The rotary electric machine comprises fins provided on a second surface of the case that faces the other end of the rotor core, and disposed on a circumference centered on the rotation center axis of the rotor.

Description

rotating electrical machines

[0001] The present invention relates to a rotating electric machine.

[0002] JP2015-012669A discloses a vehicle electric motor equipped with a cooling structure, which cools the internal mechanism by taking in outside air through an air inlet in a casing and releasing it through an exhaust port.

[0003] Such vehicle electric motors take in outside air to cool the internal mechanisms, so there is a risk of moisture entering from the outside, and it has been necessary to strengthen insulation measures.

[0004] The present invention has been made in view of the above problems, and has an object to provide a rotating electric machine capable of cooling the internal mechanism without taking in outside air.

[0005] According to one aspect of the present invention, a rotating electric machine is capable of cooling a rotor housed in a case. The rotating electric machine includes: a first passage formed in a rotor core of the rotor, communicating a first space at one end of the rotor core with a second space at the other end of the rotor core inside the rotating electric machine; and a second passage located radially outward of the first passage, communicating the first space with the second space. The rotating electric machine also includes: a fan that rotates with the rotor and circulates gas from the first space through the first passage, the second space, and the second passage in this order, and back into the first space; and a guide surface provided on a first surface of the case facing the one end of the rotor core, and guiding gas from the second passage to the first passage. The rotating electric machine also includes fins provided on a second surface of the case facing the other end of the rotor core, and arranged circumferentially about the central axis of rotation of the rotor.

[0006] Fig. 1 is a cross-sectional view showing a rotating electric machine according to this embodiment. Fig. 2 is a perspective view showing a wall portion of an inner housing as viewed from a second surface side. Fig. 3 is a perspective view showing a rotor disposed inside a stator. Fig. 4 is a perspective view showing a rotor core as viewed from one end side. Fig. 5 is a perspective view showing a rotor core as viewed from the other end side. Fig. 6 is a view showing a modified example, and is a perspective view showing a wall portion of an inner housing as viewed from a second surface side.

[0007] <Embodiments> Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0008] Fig. 1 is a cross-sectional view showing a rotating electric machine 10 according to this embodiment. Fig. 2 is a perspective view showing a wall portion 70 of an inner housing 52 as viewed from the second surface 44 side. Fig. 3 is a perspective view showing a rotor 14 disposed inside a stator 50. Fig. 4 is a perspective view showing a rotor core 16 as viewed from one end 16A side. Fig. 5 is a perspective view showing a rotor core 16 as viewed from the other end 16B side.

[0009] 1, a rotating electric machine 10 according to this embodiment is mounted on, for example, an electric vehicle as a vehicle. The rotating electric machine 10 constitutes a drive source for driving the vehicle.

[0010] The rotating electric machine 10 functions as an electric motor that supplies driving force during running, moves the vehicle forward when rotating in the forward direction, and also functions as a generator during regenerative braking.

[0011] When the rotating electric machine 10 operates at high speed and high output, copper loss, iron loss, etc. increase. As a result, the rotating electric machine 10 becomes hot and requires cooling. The rotating electric machine 10 is capable of cooling the rotor 14 housed in the case 12.

[0012] The rotating electric machine 10 includes a first passage 26 formed in the rotor core 16 of the rotor 14, which connects a first space 20 on one end 16A side of the rotor core 16 to a second space 22 on the other end 16B side of the rotor core 16 inside the rotating electric machine 10. The rotating electric machine 10 also includes a second passage 28 located radially outward of the first passage 26 in the radial direction RD, which connects the first space 20 to the second space 22.

[0013] The rotating electric machine 10 includes a fan 30 (see FIGS. 4 and 5 ) that rotates together with the rotor 14 and circulates the gas in the first space 20 through the first passage 26, the second space 22, and the second passage 28 in this order, back into the first space 20. The gas is composed of air within the case 12, but may also be composed of another gas sealed within the case 12.

[0014] The rotating electric machine 10 includes a guide surface 42 that is provided on a first surface 40 of the case 12 facing one end 16A of the rotor core 16 and that guides gas from the second passage 28 to the first passage 26. The rotating electric machine 10 also includes fins 46 that are provided on a second surface 44 of the case 12 facing the other end 16B of the rotor core 16 and that are arranged circumferentially about the central axis C of rotation of the rotor 14.

[0015] (Case) The case 12 includes an inner housing 52 that surrounds the rotor 14 and the stator 50 that is disposed on the outer periphery of the rotor 14, and an outer housing 54 that is disposed outside the inner housing 52. The case 12 also includes a flow path 56 that is formed between the inner housing 52 and the outer housing 54 and through which a refrigerant flows. The refrigerant is composed of cooling water, but may be composed of other liquids.

[0016] The inner housing 52 has a cylindrical tubular portion 60. A cover 62 that closes the opening of the tubular portion 60 is attached to one end 60A of the tubular portion 60. The inner surface of the cover 62 forms the first surface 40 that faces one end 16A of the rotor core 16. A bearing portion 66 is attached to the other end 60B of the tubular portion 60.

[0017] A wall portion 70 is integrally formed at the other end of the cylindrical portion 60. The wall portion 70 covers the end-side opening of the cylindrical portion 60. The wall portion 70 is disposed at a position that is set back toward the cylindrical portion one end 60A side from the cylindrical portion other end 60B of the cylindrical portion 60. As a result, the cylindrical portion 60 is formed with an extension portion 72 that extends toward the other end side beyond the wall portion 70, and the extension portion 72 is formed to be thicker than the cylindrical portion 60.

[0018] A step 74 recessed toward the cylindrical end 60A is formed in the center of the wall 70. The step 74 of the wall 70 constitutes the second surface 44 described above that faces the other end 16B of the rotor core 16. An insertion hole 76 opens in the center of the step 74 of the wall 70.

[0019] The outer peripheral surface of the cylindrical stator 50 is disposed in close contact with the inner surface of the tubular portion 60. The stator 50 in close contact with the tubular portion 60 is cooled by the refrigerant flowing through the flow passage 56.

[0020] A pair of grooves 80 are formed in a spiral shape on the outer surface of the tubular portion 60. These grooves 80 form the aforementioned communication passage 56 in a spiral shape along the outer peripheral surface of the tubular portion 60 between the inner housing 52 and the outer housing 54.

[0021] The flow path 56 has an outward path 82 through which the refrigerant supplied from upstream flows from the one end 60A side of the tubular portion 60 toward the wall portion 70 on the other end 60B side of the tubular portion 60, and a return path 84 through which the refrigerant flows from the other end 60B side of the tubular portion on the wall portion 70 side toward the one end 60A side of the tubular portion.

[0022] (Bearing Portion) The bearing portion 66 has a protruding portion 90 that protrudes toward the wall portion 70 of the inner housing 52. The protruding portion 90 is fitted into a cylindrical extending portion 72 that is formed on the other end 60B of the cylindrical portion 60 of the inner housing 52. The bearing portion 66 has a cylindrical portion 92 that communicates with the insertion hole 76 of the wall portion 70. The shaft 14A of the rotor 14 that has passed through the insertion hole 76 of the wall portion 70 is inserted into the cylindrical portion 92.

[0023] A coolant passage 100 is formed on the outer periphery of the cylindrical portion 92 by a space formed between the wall portion 70 and the protruding portion 90 of the bearing portion 66 .

[0024] The refrigerant passage 100 communicates with the outward passage 82 and the return passage 84 that constitute the communication passage 56 via a pair of communication passages 102 formed in the inner housing 52 .

[0025] The coolant is supplied to the coolant path 100 from the outgoing path 82 through one of the communication paths 102. The coolant that has passed through the coolant path 100 is discharged to the return path 84 through the other of the communication paths 102. The coolant discharged from the return path 84 is sent to a radiator (not shown) by a pump (not shown). The coolant in the radiator cools an inverter (not shown) that controls the rotating electric machine 10, and then is sent to the outgoing path 82 that constitutes the communication path 56.

[0026] A coolant flows through the coolant passage 100 to cool an inverter (not shown) and also to cool the stator 50 when flowing through the flow passage 56. The case 12 includes the coolant passage 100 through which the coolant for cooling the rotating electrical machine 10 flows.

[0027] (Fins) The fins 46 described above are integrally formed on the second surface 44 of the stepped portion 74 of the wall portion 70 on the rotor core 16 side, and the refrigerant passage 100 is located on the back side of the second surface 44 on which the fins 46 are provided.

[0028] 2 , the fins 46 include intermittent fins 110 and continuous fins 112 that are formed continuously on concentric circles centered on the central axis of rotation C. The continuous fins 112 are arranged on the outer periphery of the intermittent fins 110.

[0029] The intermittent fin 110 is composed of a first intermittent fin 120, a second intermittent fin 122, and a third intermittent fin 124, which are formed on three concentric circles with different radii. The first intermittent fin 120 is arranged closer to the central axis than the second intermittent fin 122. The second intermittent fin 122 is arranged closer to the central axis than the third intermittent fin 124.

[0030] In two adjacent intermittent fins (120, 124, 126) in the radial direction RD, the gaps (120B, 122B) between the fin pieces (120A, 122A) constituting the intermittent fin (120, 122) located on the inner diameter side and the gaps (122B, 124B) between the fin pieces (122A, 124A) constituting the intermittent fin (122, 124) located on the outer diameter side are positioned with a shift in position in the circumferential direction CD.

[0031] Specifically, the first gaps 120B between the first fin pieces 120A constituting the first interrupted fin 120 on the inner diameter side and the second gaps 122B between the second fin pieces 122A constituting the second interrupted fin 122 on the outer diameter side are positioned at positions offset in the circumferential direction CD. Also, the second gaps 122B between the second fin pieces 122A constituting the second interrupted fin 122 on the inner diameter side and the third gaps 124B between the third fin pieces 124A constituting the third interrupted fin 124 on the outer diameter side are positioned at positions offset in the circumferential direction CD.

[0032] As a result, the flow path length of the gas flowing from the inner diameter side to the outer diameter side along the second surface 44 is longer than when the gaps 120B, 122B, 124B of each intermittent fin 120, 122, 124 are arranged side by side in the radial direction RD.

[0033] The circumferential length of the third fin piece 124A is longer than the circumferential length of the second fin piece 122A, and the circumferential length of the second fin piece 122A is longer than the circumferential length of the first fin piece 120A.

[0034] This continuous fin 112 is disposed outside the third intermittent fin 124. The heights of the fins 112, 120, 122, and 124 are all the same, but the fins positioned radially outward may be higher.

[0035] 1, the cover 62 has a protrusion 134 disposed inside a coil end 132 that protrudes axially from the coil 130 of the stator 50. A through hole 136 that penetrates the cover 62 is formed in the center of the protrusion 134. The shaft 14A of the rotor 14 is inserted into the through hole 136.

[0036] The surface of the protrusion 134 facing the rotor 14 constitutes the first surface 40 described above, which faces one end 16A of the rotor core 16. A U-shaped groove 140 having a U-shaped cross section is formed in the first surface 40. The U-shaped groove 140 is formed in a ring shape that surrounds the through hole 136.

[0037] The tip of the outer peripheral side surface of the U-shaped groove 140 is located at a position corresponding to the outer edge of the second passage 28. The tip of the inner peripheral side surface of the U-shaped groove 140 is located at a position corresponding to the edge of the first passage 26 on the side of the central axis C of rotation. As a result, the surface of the U-shaped groove 140 forms the above-mentioned guide surface 42 that guides the gas from the second passage 28 to the first passage 26.

[0038] 3, the stator 50 is formed in a cylindrical shape. The stator 50 is formed with a plurality of teeth 150 extending toward the central axis of rotation C. A coil 130 is wound around each tooth 150.

[0039] (Rotor) The rotor core 16 of the rotor 14 is formed in a cylindrical shape and is disposed within the stator 50. A gap (air gap) is formed between an outer peripheral surface 160 of the rotor core 16 and an inner peripheral surface 162 of the stator 50, and this gap serves as the second passage 28 described above.

[0040] A shaft insertion hole 166, through which the shaft 14A (see FIG. 1) is inserted, is formed in the center of the rotor core 16. A plurality of openings penetrating in the axial direction AD are formed on the outer periphery of the shaft insertion hole 166, and these openings constitute the first passage 26 described above.

[0041] A plurality of accommodating holes 168 are formed radially outward of each first passage 26 and on the periphery of the rotor core 16. A permanent magnet is disposed in each accommodating hole 168. The permanent magnet housed in each accommodating hole 168 receives magnetic force from the excitation-controlled teeth 150, causing the rotor 14 to rotate.

[0042] 4, a first fan 170 that constitutes part of the fan 30 is provided at one end 16A of the rotor core 16. The first fan 170 is fixed to the shaft 14A and rotates together with the rotor core 16.

[0043] The first fan 170 is formed in a disk shape with approximately the same diameter as the rotor core 16. A first ring-shaped opening 172 formed in the first fan 170 has a plurality of first blades 174 arranged in the circumferential direction CD. The first fan 170 is a mixed flow fan in which the first blades 174 are inclined so as to guide the gas in the first space 20 (see FIG. 1 ) to the first passage 26 (see FIG. 1 ) when the rotor core 16 rotates in the forward rotation direction CW.

[0044] 5, a second fan 180 that constitutes part of the fan 30 is provided at the other end 16B of the rotor core 16. The second fan 180 is fixed to the shaft 14A and rotates together with the rotor core 16.

[0045] The second fan 180 is formed in a disk shape with approximately the same diameter as the rotor core 16. A second ring-shaped opening 182 formed in the second fan 180 has a plurality of second blades 184 arranged in the circumferential direction CD. The second fan 180 is a mixed flow fan that discharges gas from the first passage 26 (see FIG. 1 ) into the second space 22 (see FIG. 1 ) when the rotor core 16 rotates in the forward rotation direction CW.

[0046] Furthermore, the second fan 180 blows the gas discharged from the first passage 26 (see FIG. 1) to the second space 22 (see FIG. 1) when the rotor core 16 rotates in the forward rotation direction CW, toward the fins 46 formed integrally with the stepped portion 74 (see FIG. 1) of the wall portion 70 (see FIG. 1). The gas from the second fan 180 is blown toward the inside of the first intermittent fins 120.

[0047] In this embodiment, the fan 30 is described as being composed of the first fan 170 and the second fan 180, but the fan 30 is not limited to this configuration. The fan 30 may be composed of, for example, only the first fan 170 or only the second fan 180.

[0048] The gas blown onto the inside of the first intermittent fin 120 is sent through the first gap 120B to the inner periphery of the second intermittent fin 122. The gas sent to the inner periphery of the second intermittent fin 122 is sent through the second gap 122B to the inner periphery of the third intermittent fin 124. The gas sent to the inner periphery of the third intermittent fin 124 is sent through the third gap 124B to the inner periphery of the continuous fin 112. The gas sent to the inner periphery of the continuous fin 112 is prevented from spreading outward and is sent to the second passage 28 (see FIG. 1 ).

[0049] <Modification> A modification of the present embodiment will be described with reference to Fig. 6 etc. Fig. 6 is a perspective view showing the modification, illustrating the wall portion 70 of the inner housing 52 as viewed from the second surface 44 side.

[0050] The rotating electric machine 10 according to the modified example differs from the embodiment in the fin pieces (196, 198) of the interrupted fins 110. In this modified example, the same or equivalent parts as those in the embodiment are denoted by the same reference numerals and description thereof will be omitted, and only the parts that differ from the embodiment will be described.

[0051] As shown in Figure 6, the fins 46 of the rotating electric machine 10 according to the modified example include intermittent fins 110 formed intermittently and continuous fins 112 formed continuously on a concentric circle centered on the central axis of rotation C, and the continuous fins 112 are arranged on the outer periphery of the intermittent fins 110.

[0052] The intermittent fins 110 are composed of inner intermittent fins 190 arranged on the inner diameter side and outer intermittent fins 192 arranged on the outer diameter side.

[0053] The fin pieces 196 constituting the inner discontinuous fin 190 extend outward in the forward rotation direction CW of the rotor 14 (see FIG. 1 ) as viewed in the axial direction. The fin pieces 198 constituting the outer discontinuous fin 192 extend outward in the forward rotation direction CW as viewed in the axial direction.

[0054] Furthermore, the gaps 200 between the fin pieces 196 of the inner intermittent fin 190 and the gaps 202 between the fin pieces 198 of the outer intermittent fin 192 may be arranged with a shift in position in the circumferential direction CD.

[0055] (Operations and Effects) The rotating electric machine 10 of this embodiment is capable of cooling the rotor 14 housed in the case 12. The rotating electric machine 10 includes a first passage 26 formed in the rotor core 16 of the rotor 14, communicating a first space 20 on one end 16A of the rotor core 16 with a second space 22 on the other end 16B of the rotor core 16 inside the rotating electric machine 10. The rotating electric machine 10 includes a second passage 28 located radially outward of the first passage 26 and communicating the first space 20 with the second space 22. The rotating electric machine 10 includes a fan 30 that rotates together with the rotor 14 and circulates gas in the first space 20 through the first passage 26, the second space 22, and the second passage 28 in this order, into the first space 20. The rotating electric machine 10 includes a guide surface 42 that is located on a first surface 40 of the case 12 facing the one end 16A of the rotor core 16 and that guides gas from the second passage 28 to the first passage 26. The rotating electric machine 10 includes fins 46 provided on a second surface 44 of the case 12 facing the other end 16B of the rotor core 16 and arranged on a circumference centered on the central axis C of rotation of the rotor 14 .

[0056] In this configuration, gas inside the case 12 is circulated in the following order: first passage 26 of rotor core 16, second space 22 on the other end 16B side of rotor core 16, second passage 28 radially outward of first passage 26 in the radial direction RD, and first space 20 on the one end 16A side of rotor core 16. In this circulation path, movement of gas from second passage 28 to first passage 26 is promoted by guide surface 42 provided on first surface 40.

[0057] The gas circulating inside the case 12 comes into contact with the fins 46 provided on the second surface 44 in the second space 22. Heat is then exchanged between the gas and the fins 46, and the heat of the gas is absorbed by the fins 46. The heat absorbed by the fins 46 is released to the case 12 side through the second surface 44.

[0058] Furthermore, by circulating the gas cooled in the second space 22 within the case 12, the rotating electric machine 10 is able to efficiently cool the internal mechanisms of the case 12, such as the rotor 14, without taking in outside air.

[0059] Furthermore, in the rotating electric machine 10, the second passage 28 is provided radially outward of the first passage 26, and the gas cooled in the second space 22 first passes through the second passage 28. This allows the gas cooled in the second space 22 to more efficiently cool the permanent magnets arranged on the outer edge of the rotor core 16. This allows the rotating electric machine 10 to effectively suppress the effect of heat on the permanent magnets.

[0060] The fan 30 also includes a first fan 170 that is provided at one end 16A of the rotor core 16 and that guides the gas in the first space 20 to the first passage 26. The fan 30 also includes a second fan 180 that is provided at the other end 16B of the rotor core 16 and that exhausts the gas in the first passage 26 to the second space 22.

[0061] In this configuration, the rotating electric machine 10 can guide the gas in the first space 20 to the first passage 26 by the first fan 170 provided at one end 16A of the rotor core 16. In addition, the rotating electric machine 10 can exhaust the gas in the first passage 26 to the second space 22 by the second fan 180 provided at the other end 16B of the rotor core 16.

[0062] Therefore, the rotating electric machine 10 can improve the gas circulation efficiency compared to a case where the rotating electric machine 10 is configured only with the first fan 170 that guides the gas in the first space 20 to the first passage 26, or only with the second fan 180 that exhausts the gas in the first passage 26 to the second space 22.

[0063] The case 12 also includes a coolant passage 100 through which a coolant flows to cool the stator 50 of the rotating electrical machine 10, and the coolant passage 100 is located on the rear side of the second surface 44 on which the fins 46 are provided.

[0064] With this configuration, the heat of the gas transferred to the fins 46 can be cooled by the refrigerant flowing through the refrigerant path 100. Therefore, the rotating electric machine 10 can effectively use the refrigerant that cools the stator 50 to dissipate the heat stored in the fins 46.

[0065] The fins 46 also include intermittent fins 110 formed intermittently and continuous fins 112 formed continuously on a concentric circle centered on the central axis of rotation C, and the continuous fins 112 are arranged on the outer periphery of the intermittent fins 110.

[0066] In this configuration, the gas sent from the first passage 26 formed in the rotor core 16 to the second space 22 spreads to the outer periphery through the gaps (120B, 122B, 124B) of the intermittent fins 110. The intermittent fins 110 through which the gas passes have an increased surface area due to their intermittent formation. This allows the rotating electric machine 10 to increase the efficiency of heat exchange between the gas and the intermittent fins 110.

[0067] The gas that passes through the gaps (120B, 122B, 124B) of the intermittent fins 110 is prevented from spreading further outward by the continuous fins 112, and is guided to the second passage 28 located radially outward from the first passage 26.

[0068] The fin 46 also includes a plurality of interrupted fins (120, 122, 124), which are formed to form concentric circles with different radii. In two adjacent interrupted fins (120, 122, 124) in the radial direction RD, the gaps (120B, 122B) between the fin pieces (120A, 122A) constituting the interrupted fin (120, 122) located on the inner diameter side and the gaps (122B, 124B) between the fin pieces (122A, 124A) constituting the interrupted fin (122, 124) located on the outer diameter side are positioned with a shift in position in the circumferential direction CD.

[0069] In such a configuration, the flow path length of the gas flowing from the inner diameter side to the outer diameter side is longer than when the gaps (120B, 122B, 124B) of each intermittent fin (120, 122, 124) are arranged side by side in the radial direction RD.

[0070] Therefore, in the rotating electric machine 10, the time it takes for the gas to pass through each of the intermittent fins (120, 122, 124) is longer, and heat exchange between the gas and each of the intermittent fins (120, 122, 124) can be carried out over a longer period of time.

[0071] The case 12 also includes an inner housing 52 that surrounds the rotor 14 and a stator 50 that is disposed on the outer periphery of the rotor 14, and an outer housing 54 that is disposed outside the inner housing 52. The case 12 also includes a flow passage 56 that is formed between the inner housing 52 and the outer housing 54 and through which a refrigerant flows. The flow passage 56 communicates with a refrigerant passage 100.

[0072] In this configuration, the rotating electric machine 10 can cool the stator 50 arranged inside the inner housing 52 from its outer periphery by the refrigerant in the flow passage 56 formed between the inner housing 52 and the outer housing 54.

[0073] Furthermore, the rotating electrical machine 10 can cool the internal mechanism of the case 12 by utilizing the refrigerant in the flow passage 56 that cools the stator 50 from the outer periphery.

[0074] The second passage 28 is a gap formed between the outer peripheral surface 160 of the rotor core 16 and the inner peripheral surface 162 of the stator 50 .

[0075] In this configuration, the rotating electric machine 10 can arrange the second passage 28 radially outward from the first passage 26 without forming an additional passage consisting of an opening in the rotor core 16.

[0076] In a modification of this embodiment, the rotating electric machine 10 constitutes a drive source that rotates forward to move the vehicle forward. The fin pieces (196, 198) that constitute the intermittent fin 110 extend outward as they move in the forward rotation direction CW, which is the direction in which the rotor 14 rotates forward, as viewed in the axial direction.

[0077] In this configuration, the fin pieces (196, 198) of the discontinuous fins 110 extend outward in the forward rotation direction CW. Therefore, during forward driving when the thermal load is large, the rotating electric machine 10 can improve the flow of air from the inner discontinuous fins 190 serving as the inner diameter side discontinuous fins to the outer diameter side discontinuous fins 192 serving as the outer diameter side discontinuous fins.

[0078] This makes it possible to improve the efficiency of gas circulation.

[0079] The above describes the embodiments and various modifications of the present invention, but the above embodiments merely illustrate some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0080] In the above-described embodiment, the rotating electric machine 10 is used in an electric vehicle, but the application of the rotating electric machine 10 is not limited to this. The rotating electric machine 10 may be used for other purposes.

Claims

1. A rotating electric machine capable of cooling a rotor housed in a case, comprising: a first passage formed in a rotor core of the rotor, communicating a first space on one end side of the rotor core and a second space on the other end side inside the rotating electric machine; a second passage provided radially outward of the first passage, communicating the first space and the second space; a fan that rotates with the rotor, and circulates gas from the first space through the first passage, the second space, and the second passage in that order, into the first space; a guide surface provided on a first surface of the case facing one end of the rotor core, and guiding gas from the second passage to the first passage; and fins provided on a second surface of the case facing the other end of the rotor core, and arranged on a circumference centered on the central axis of rotation of the rotor.

2. A rotating electric machine according to claim 1, wherein the fans include a first fan provided at one end of the rotor core and directing gas in the first space to the first passage, and a second fan provided at the other end of the rotor core and discharging gas in the first passage to the second space.

3. A rotating electric machine according to claim 2, wherein the case is provided with a coolant passage through which a coolant flows to cool the stator of the rotating electric machine, and the coolant passage is located on the back side of the second surface on which the fins are provided.

4. A rotating electric machine according to claim 3, wherein the fins include intermittent fins formed intermittently and continuous fins formed continuously on concentric circles centered on the central axis of rotation, and the continuous fins are arranged on the outer periphery of the intermittent fins.

5. A rotating electric machine according to claim 4, wherein the rotating electric machine constitutes a drive source that rotates in the normal direction to move a vehicle forward, and the fin pieces that constitute the intermittent fins extend outward as the rotor moves in the normal direction when viewed in the axial direction.

6. A rotating electric machine according to claim 4, wherein the fins include a plurality of the interrupted fins, which are formed to form concentric circles of different radii, and in two of the interrupted fins that are adjacent in the radial direction, the gap between the fin pieces that make up the interrupted fin located on the inner diameter side and the gap between the fin pieces that make up the interrupted fin located on the outer diameter side are positioned so as to be offset in the circumferential direction.

7. A rotating electric machine according to claim 3, wherein the case comprises an inner housing surrounding the rotor and the stator arranged on the outer periphery of the rotor, an outer housing arranged outside the inner housing, and a flow passage formed between the inner housing and the outer housing through which the refrigerant flows, the flow passage communicating with the refrigerant passage.

8. A rotating electric machine according to claim 7, wherein the second passage is a gap formed between the outer peripheral surface of the rotor core and the inner peripheral surface of the stator.

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