Rotating electric machine

Abstract

This rotating electric machine (100) comprises: a stator (2) provided with a cylindrical stator outer peripheral part (21); and a flow path forming body (4). The flow path forming body (4) is provided so as to be in contact with a stator outer peripheral surface (21A) of the stator outer peripheral part (21). A heat medium flow path (4R) is formed inside the flow path forming body (4). The flow path forming body (4) is provided with: an inner cylindrical part (41) in contact with the stator outer peripheral surface (21A); and an outer cylindrical part (42) fitted to the inner cylindrical part (41) from the outside in the radial direction (R). The outer cylindrical part (42) has a lower thermal conductivity than the inner cylindrical part (41).

Description

Rotating electric machines

[0001] The present invention relates to a rotating electric machine that transfers heat between itself and a heat medium.

[0002] An example of such a rotating electric machine is disclosed in the following Patent Document 1. In the following description of this background art, reference numerals and names in Patent Document 1 will be cited in parentheses.

[0003] Patent Document 1 discloses a rotating electric machine (1) having a structure (cooling structure) for transferring heat between the rotating electric machine (1) and a heat medium (cooling water). The structure (cooling structure) includes a flow path forming body (flow path forming member 90). The flow path forming body (flow path forming member 90) forms a flow path (refrigerant flow path 300) through which the heat medium (cooling water) flows around the rotating electric machine (1).

[0004] International Patent Publication No. 2024 / 075613

[0005] Here, the flow path forming body (flow path forming member 90) is often formed from a material with good thermal conductivity in order to transfer heat generated in the rotating electric machine (1) to the heat medium (coolant). However, if the thermal conductivity of the flow path forming body (flow path forming member 90) is increased, the heat of the flow path forming body and the heat medium (coolant) is easily transferred to components around the flow path forming body (flow path forming member 90) and other heat-transferable media, leaving room for improvement in terms of effective use of the heat of the heat medium.

[0006] Therefore, it is desirable to realize a rotating electrical machine that can easily and effectively utilize the generated heat.

[0007] The rotating electric machine according to the present disclosure is a rotating electric machine comprising: a stator having a cylindrical outer periphery of the stator; and a flow path forming body arranged in contact with the outer periphery of the stator and having a flow path for a heat medium formed therein, wherein the direction perpendicular to the axis of the stator is the radial direction, and the flow path forming body comprises a cylindrical inner cylindrical portion in contact with the outer periphery of the stator, and a cylindrical outer cylindrical portion fitted to the inner cylindrical portion from the outside in the radial direction, and the outer cylindrical portion has a lower thermal conductivity than the inner cylindrical portion.

[0008] This configuration minimizes heat transfer between the inner and outer cylindrical portions, making it difficult for the heat of the stator to be transferred to components located radially outside the outer cylindrical portion or other heat-transferable mediums. This allows the heat of the stator to be efficiently transferred to the heat medium, making it easier to effectively utilize the heat of the stator.

[0009] FIG. 2 is a schematic diagram illustrating a rotating electric machine according to an embodiment; FIG. 3 is a cross-sectional view taken along line II-II of the rotating electric machine shown in FIG. 1; and FIG. 4 is a cross-sectional view illustrating another example of the rotating electric machine according to an embodiment.

[0010] A rotating electric machine 100 according to an embodiment will be described with reference to Figures 1 and 2. In this application, the rotating electric machine 100 is used as a concept that includes a motor (electric motor), a generator (electric power generator), and a motor-generator that functions as both a motor and a generator as needed. The rotating electric machine 100 according to this embodiment is a motor-generator used as a driving power source for vehicles such as hybrid vehicles and electric vehicles.

[0011] 1, the rotating electric machine 100 includes a rotor 1, a stator 2, a case 3 that houses the stator 2, and a flow path formation body 4 that has formed therein a flow path 4R through which a heat medium flows to transfer heat between the rotor 1 and the stator 2. The rotating electric machine 100 of this embodiment is an inner rotor type. Therefore, the rotating electric machine 100 illustrated in FIG. 1 has a structure in which the rotor 1 is housed in a cylindrical stator 2 that extends in the direction of the axis Z, and the stator 2 is housed in the case 3.

[0012] Hereinafter, for ease of explanation, the direction along the axis Z of the stator 2 will be referred to as the axial direction X. One side in the axial direction X will be referred to as the first axial side X1. The side opposite the first axial side X1 will be referred to as the second axial side X2. The direction going around the axis Z of the stator 2 will be referred to as the circumferential direction C, and the direction perpendicular to the axis Z of the stator 2 will be referred to as the radial direction R. In the radial direction R, with respect to a reference configuration, the side closer to the axis Z of the stator 2 will be referred to as the radial inner side R1, and the side farther from the axis Z of the stator 2 will be referred to as the radial outer side R2.

[0013] In this embodiment, the rotating electric machine 100 is a rotating field type. The rotor 1 is provided with permanent magnets and electromagnets, and the stator 2 is provided with coils.

[0014] The rotor 1 rotates relative to the stator 2. In this embodiment, the rotor 1 is rotatably supported by a case 3, and the stator 2 is fixed to the case 3. The rotor 1 illustrated in FIGS. 1 and 2 includes a rotor core 11 and a rotor shaft 12 connected to the rotor core 11 so as to rotate integrally with the rotor core 11. The rotor core 11 rotates around a rotation axis that overlaps with the axis Z of the stator 2. The rotor shaft 12 is attached to a radially inner portion R1 of the rotor core 11 and is rotatably supported by the case 3 via bearings B. In the example illustrated in FIG. 1 , a pair of bearings B support the rotor shaft 12. One of the pair of bearings B is disposed on a first axial side X1 relative to the rotor core 11, and the other of the pair of bearings B is disposed on a second axial side X2 relative to the rotor core 11.

[0015] The rotor shaft 12 is connected to various mechanical elements (hereinafter referred to as rotating mechanical elements) that utilize rotational force, such as a drive device connected to a wheel. In the example shown in Fig. 1 , the rotor shaft 12 is connected to the rotating mechanical elements at an end on a first axial side X1. Note that the location on the rotor shaft 12 to which the rotating mechanical elements are connected is not limited to the end on the first axial side X1 of the rotor shaft 12. For example, the rotating mechanical elements may be connected to an end on a second axial side X2 of the rotor shaft 12.

[0016] The stator 2 includes a cylindrical stator outer periphery 21. The stator outer periphery 21 is a portion disposed radially outward R2 relative to the rotor core 11, and includes a stator outer periphery surface 21A along the circumferential direction C. In this embodiment, at least the rotor core 11 is housed in a space surrounded by the stator outer periphery 21. Although not shown, the stator 2 includes a cylindrical stator core and a stator coil wound around the stator core. Here, in this embodiment, the stator core constitutes the stator outer periphery 21. In this embodiment, the outer periphery surface of the stator core corresponds to the stator outer periphery surface 21A.

[0017] In this embodiment, the rotor 1 and the stator 2 have the function of generating a rotational force to be transmitted to the rotating mechanical elements and the function of generating electricity using the rotational force transmitted from the rotating mechanical elements. Specifically, the rotor core 11 constituting the rotor 1 rotates by exciting the stator coil. As the rotor core 11 rotates, the rotational force is transmitted to the rotating mechanical elements via the rotor shaft 12. On the other hand, the rotor core 11 may also receive rotational force from the rotating mechanical elements via the rotor shaft 12. As a result, the rotor core 11 rotates, and electric power is generated in the stator 2.

[0018] In both cases where the rotational force transmitted to the rotating machine elements is generated in the rotor 1 and where the rotational force of the rotating machine elements is transmitted to the rotor 1, when the rotor 1 rotates, not only the rotational force and power of the rotor 1 but also heat and vibration are generated in the rotor 1 and the stator 2. The heat generated by the rotation of the rotor 1 is transmitted to components arranged radially outward R2 from the stator 2 and other heat transfer media, which are media for heat transfer. In addition, the vibrations caused by the rotation of the rotor 1 are transmitted to the case 3 and other components through the components in contact with the rotor 1 and stator 2.

[0019] The case 3 includes a cylindrical outer peripheral wall 31 that covers the stator 2 from the radial outside R2. In this embodiment, the outer peripheral wall 31 covers the stator outer peripheral surface 21A from a position spaced apart in the radial direction R. The outer peripheral wall 31 illustrated in FIG. 1 has a dimension in the axial direction X that is larger than the dimensions in the axial direction X of the rotor core 11 and the stator outer peripheral portion 21. Therefore, the rotor core 11 and the stator outer peripheral portion 21 are each entirely contained within a space surrounded by the outer peripheral wall 31.

[0020] In this embodiment, the outer peripheral wall 31 has an opening at its end on the first axial side X1 that leads to a space surrounded by the outer peripheral wall 31. The rotor shaft 12 is arranged to straddle the opening. In the example shown in FIG. 1 , the opening is covered by a cover 32 made of a separate member, except for the portion where the rotor shaft 12 is arranged. The cover 32 is fixed to the end of the outer peripheral wall 31 on the first axial side X1 with fastening parts 33 such as bolts. In the example shown in FIG. 1 , the cover 32 is fixed to the outer peripheral wall 31 via a fixing portion 4F, which will be described later. In addition, the cover 32 has a first retaining portion 32A that retains a bearing B that is arranged on the first axial side X1 with respect to the rotor core 11. Meanwhile, in this embodiment, the end of the outer peripheral wall 31 on the second axial side X2 is closed. The case 3 illustrated in FIG. 1 has a closing portion 34 that closes the end of the outer peripheral wall 31 on the second axial side X2. Here, the outer peripheral wall 31 and the closing portion 34 are integrally formed. The blocking portion 34 is disposed at a position spaced from the rotor core 11 and the stator outer periphery 21 toward the second axial side X2. In addition, the blocking portion 34 includes a second retaining portion 34A that retains the bearing B disposed on the second axial side X2 relative to the rotor core 11.

[0021] The flow path forming body 4 is provided in contact with the stator outer peripheral surface 21A, and has a flow path 4R for the heat medium formed therein. The heat medium is a fluid such as cooling water or oil, and is a medium for transferring heat. In this embodiment, the flow path forming body 4 covers the stator outer peripheral surface 21A from the radial outside R2. According to this configuration, heat accumulated in the stator outer peripheral portion 21 due to the rotation of the rotor 1, etc., is transferred from the stator outer peripheral surface 21A via the flow path forming body 4 to the heat medium. Preferably, the flow path forming body 4 covers the entire stator outer peripheral surface 21A.

[0022] In this embodiment, the flow path forming body 4 fixes the stator 2 to the case 3. Therefore, the stator 2 is fixed to the flow path forming body 4. The flow path forming body 4 includes a fixing portion 4F fixed to the case 3. The fixing portion 4F extends from an end portion on the axial first side X1 of the inner cylindrical portion 41 (described later) toward the radially outer side R2. The radial dimension R of the fixing portion 4F is set to be larger than the radial dimension R of the inner circumferential surface 31A of the outer peripheral wall 31. Therefore, the fixing portion 4F abuts against the case 3 from the axial first side X1 and is fixed to the case 3 by the fastening parts 33. As described above, the fixing portion 4F shown in FIG. 1 is sandwiched between the end portion on the axial first side X1 of the outer peripheral wall 31 and the cover 32, and is fixed to the outer peripheral wall 31 together with the cover 32 by the fastening parts 33.

[0023] The flow path formation body 4 includes a cylindrical inner cylindrical portion 41 that contacts the stator outer peripheral surface 21A and a cylindrical outer cylindrical portion 42 that is fitted to the inner cylindrical portion 41 from the outside in the radial direction R. A flow path 4R is formed between the inner cylindrical portion 41 and the outer cylindrical portion 42. In this embodiment, the outer cylindrical portion 42 is a separate structure from the inner cylindrical portion 41. In the example shown in FIGS. 1 and 2 , the outer cylindrical portion 42 is disposed radially outwardly R2 from the inner cylindrical portion 41 so that its inner circumferential surface 42A faces the outer circumferential surface 41A of the inner cylindrical portion 41. The inner circumferential surface 42A of the outer cylindrical portion 42 abuts against the outer circumferential surface 41A of the inner cylindrical portion 41. In addition, although not shown in detail, a seal structure 4S is provided in the gap between the end of the inner cylindrical portion 41 on the second axial side X2 and the end of the outer cylindrical portion 42 on the second axial side X2. The seal structure 4S prevents the heat medium from entering the space on the first axial side X1 beyond the end of the second axial side X2 of the case 3. The outer cylindrical portion 42 is fitted to the inner cylindrical portion 41, for example, by being press-fitted into the inner cylindrical portion 41.

[0024] In this embodiment, the heat transfer medium flow passage 4R is formed on the outer peripheral surface 41A of the inner cylindrical portion 41. In the example shown in Fig. 1, a plurality of flow passages 4R are formed on the outer peripheral surface 41A of the inner cylindrical portion 41 along the circumferential direction C. The plurality of flow passages 4R may be at least partially connected to one another or may be independent of one another.

[0025] The heat medium is supplied to the flow path 4R, and after heat transfer between the flow path 4R and the stator 2, is discharged from the flow path 4R. For this reason, a supply path 4A for supplying the heat medium to the flow path 4R and a discharge path (not shown) for discharging the heat medium from the flow path 4R are formed in the flow path former 4. The supply path 4A extends in the axial direction X and communicates with the flow path 4R. The supply path 4A illustrated in FIG. 1 is a groove formed in the outer circumferential surface 41A of the inner cylindrical portion 41, and communicates with at least one of the multiple flow paths 4R.

[0026] In this embodiment, the heat medium is supplied from the outside of the case 3 to the flow path 4R and then discharged from the flow path 4R to the outside of the case 3. For this reason, a supply path 4A for supplying the heat medium to the flow path 4R is also formed in the fixed portion 4F. The supply path 4A provided in the fixed portion 4F at least connects the outside and the inside of the case 3. The supply path 4A illustrated in FIG. 1 is a groove formed on the surface of the fixed portion 4F facing the case 3, extending from the end on the radially outer side R2 to the end on the radially inner side R1. When the stator 2 is fixed to the case 3, the supply path 4A is located outside the case 3 and connects the flow path 4R to a supply source (not shown) that supplies the heat medium. Note that, like the supply path 4A, a discharge path (not shown) also connects at least the outside and the inside of the case 3. Like the supply path 4A, the discharge path may be provided in the fixed portion 4F or in a location other than the fixed portion 4F.

[0027] The outer cylindrical portion 42 has a lower thermal conductivity than the inner cylindrical portion 41. This makes it difficult for heat from the inner cylindrical portion 41 and the heat of the heat medium flowing through the flow path 4R to be transferred to the outer cylindrical portion 42. The outer cylindrical portion 42 may be made of a single material or a combination of multiple materials. The outer cylindrical portion 42 has a lower overall thermal conductivity than the inner cylindrical portion 41.

[0028] In the present embodiment, the inner circumferential surface 42A of the outer cylindrical portion 42 is flat. With this configuration, the structure of the outer cylindrical portion 42 is simpler than when the flow path 4R is formed in the outer cylindrical portion 42, and therefore, a material with low thermal conductivity and low formability can be used as the material for the outer cylindrical portion 42.

[0029] In the present embodiment, the outer cylindrical portion 42 has a lower thermal conductivity than both the inner cylindrical portion 41 and the outer peripheral wall 31. This configuration minimizes heat transfer between the inner cylindrical portion 41 and the case 3, making it difficult for heat from the stator 2 to be transferred to the case 3. Therefore, the heat from the stator 2 can be efficiently transferred to the heat medium, making it easier to effectively utilize the heat from the stator 2.

[0030] Preferably, outer cylindrical portion 42 has higher rigidity than inner cylindrical portion 41. According to this configuration, outer cylindrical portion 42 suppresses deformation of inner cylindrical portion 41 toward the radially outward direction R2, thereby effectively reducing vibrations transmitted from stator 2 to case 3.

[0031] Preferably, both the inner cylindrical portion 41 and the outer cylindrical portion 42 are disposed over the entire stator outer peripheral surface existing region A1 in the axial direction X. Here, the stator outer peripheral surface existing region A1 includes the region in the axial direction X where the stator outer peripheral surface 21A exists.

[0032] Furthermore, preferably, the outer peripheral wall 31 is made of metal, the inner cylindrical portion 41 is made of metal, and the outer cylindrical portion 42 is made of fiber-reinforced resin. In this embodiment, the outer peripheral wall 31 and the inner cylindrical portion 41 are made of aluminum, and the outer cylindrical portion 42 is made of carbon fiber-reinforced resin. The fibers and their orientation of the fiber-reinforced resin that makes up the outer cylindrical portion 42 are determined appropriately depending on the required rigidity. Examples of types of fibers in fiber-reinforced resin include glass fiber and aramid fiber. In addition, the resin used as the base material of the fiber-reinforced resin is also determined appropriately depending on the required heat resistance and rigidity.

[0033] Preferably, the rotating electric machine 100 further includes a foamed resin 5. The foamed resin 5 has at least heat resistance such that it is not significantly deteriorated by the heat of the stator 2. Examples of the foamed resin 5 include urethane foam and phenol foam, which have a high degree of molding flexibility and are easy to manufacture. The foamed resin 5 is disposed in the gap between the outer peripheral surface 42B of the outer tubular portion 42 and the inner peripheral surface 31A of the outer peripheral wall 31. Preferably, the foamed resin 5 is disposed in the gap between the outer tubular portion 42 and the outer peripheral wall 31 so as to compress the outer tubular portion 42 from the radially outer side R2. With this configuration, the foamed resin 5 can increase the rigidity of the outer tubular portion 42. The foamed resin 5 is filled into the gap between the outer tubular portion 42 and the outer peripheral wall 31 by, for example, heat foaming. The foamed resin 5 illustrated in FIGS. 1 and 2 is disposed throughout the stator outer peripheral surface area A1 and the circumferential direction C. Therefore, heat transfer from the outer cylindrical portion 42 to the heat transfer medium present on the radially outer side R2 of the outer cylindrical portion 42 can be kept low.

[0034] Preferably, as shown in FIG. 3 , the foamed resin 5 is disposed in a portion of the entire outer peripheral surface 42B of the outer cylindrical portion 42, and in the remaining portion, a gap 5A is formed between the outer peripheral surface 42B of the outer cylindrical portion 42 and the inner peripheral surface 31A of the outer peripheral wall 31. In this case, the foamed resin 5 is set so as to reduce the magnitude of stress in a portion where stress is relatively high in each natural vibration mode of the stator 2 determined by the rotation characteristics of the rotor 1 and the shape and rigidity of the stator 2. In the example shown in FIG. 3 , the foamed resin 5 is disposed at intervals in the circumferential direction C. This facilitates reducing vibration transmitted from the stator 2 to the case 3 when the stator 2 vibrates in a natural vibration mode in which the stator 2 deforms in-plane. In the example shown in FIG. 3 , the foamed resin 5 is filled at equal intervals in four locations in the circumferential direction C. The length along the circumferential direction C of each foamed resin 5 disposed at intervals in the circumferential direction C is longer than the length along the circumferential direction C of a gap 5A disposed between two foamed resin 5 adjacent to each other in the circumferential direction C.

[0035] Other Embodiments Next, other embodiments of the rotating electrical machine 100 will be described.

[0036] (1) In the above embodiment, the inner cylindrical portion 41 is provided with the heat medium flow passage 4R on its outer peripheral surface, and the inner peripheral surface 42A of the outer cylindrical portion 42 is flat. However, the outer peripheral surface 41A of the inner cylindrical portion 41 may be flat, and the outer cylindrical portion 42 may be provided with the heat medium flow passage 4R on its inner peripheral surface 42A. Alternatively, both the outer peripheral surface 41A of the inner cylindrical portion 41 and the inner peripheral surface 42A of the outer cylindrical portion 42 may be provided with the heat medium flow passage 4R.

[0037] (2) In the above embodiment, the outer peripheral wall 31 has been described as having an opening at one end along the axial direction X and a closed other end. However, the outer peripheral wall 31 may be configured to have openings at both ends along the axial direction X. In this case, each of the openings at both ends of the outer peripheral wall 31 along the axial direction X is covered by a cover.

[0038] (3) In the above embodiment, the stator outer periphery 21 corresponds to the stator core. However, the stator outer periphery 21 is not limited to the stator core, and may have a structure including a surface of the stator 2 facing the radially outer side R2.

[0039] (4) In the above embodiment, the bearing B arranged on the first axial side X1 with respect to the rotor core 11 is held by the first holding portion 32A, and the bearing B arranged on the second axial side X2 with respect to the rotor core 11 is held by the second holding portion 34A. However, the bearing B may be held by a component other than the cover 32 or the closing portion 34, as long as the rotor 1 rotates relative to the stator 2.

[0040] (5) In the above embodiment, the flow path forming body 4 is described as fixing the stator 2 to the case 3. However, the flow path forming body 4 does not necessarily have to include the fixing portion 4F for fixing the stator 2 to the case 3, and the stator 2 may be fixed to the case 3 directly or via a separate part. Also, in the above embodiment, the supply path 4A is described as being formed in the fixing portion 4F. However, the supply path 4A may be formed somewhere other than the fixing portion 4F as long as it can communicate between the outside and the inside of the case 3. For example, the supply path 4A that communicates between the inside and the outside of the case 3 may be a through-hole that penetrates the outer peripheral wall 31 of the case 3 in the radial direction R.

[0041] (6) In the above embodiment, the outer tubular portion 42 is described as being fitted to the inner tubular portion 41 by being press-fitted into the inner tubular portion 41. However, the inner tubular portion 41 and the outer tubular portion 42 may be configured to have a clearance fit so that the outer tubular portion 42 can be fitted to the inner tubular portion 41 without being press-fitted. In this case, an adhesive may be filled in the gap between the inner tubular portion 41 and the outer tubular portion 42. Furthermore, when the outer tubular portion 42 is made of fiber-reinforced resin, fibers may be wound around the outer peripheral surface 41A of the inner tubular portion 41, and then the fibers wound around the outer peripheral surface 41A of the inner tubular portion 41 may be impregnated with resin.

[0042] (7) In the above embodiment, the foamed resin 5 is described as being disposed in the gap between the outer peripheral surface 42B of the outer cylindrical portion 42 and the inner peripheral surface 31A of the outer peripheral wall 31. However, instead of disposing the foamed resin 5 in the gap between the outer peripheral surface 42B of the outer cylindrical portion 42 and the inner peripheral surface 31A of the outer peripheral wall 31, air may be sealed in the gap. Furthermore, argon gas, krypton gas, or other gases may be sealed in the gap instead of the foamed resin 5. This is because these gases have lower thermal conductivity than air and a higher specific gravity than air, making convection less likely to occur and making it easier to improve thermal insulation performance. Furthermore, glass wool, rock wool, or other fibrous materials may be disposed in the gap instead of the foamed resin 5. This is because such fibrous materials not only have high heat resistance but also excellent sound absorption properties, making it possible to reduce vibration and noise transmitted from the stator 2 to the case 3. A combination of foamed resin 5, air, gas, and fibrous materials may be disposed in the gap.

[0043] (8) In the above embodiment, the outer cylindrical portion 42 is described as being made of fiber-reinforced resin. However, the outer cylindrical portion 42 may be an iron pipe.

[0044] (9) The configurations disclosed in the above-described embodiments can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Regarding other configurations, the embodiments disclosed in this specification are merely examples in all respects. Therefore, various modifications can be made as appropriate within the scope of the present disclosure.

[0045] Summary of the Present Embodiment The following provides a summary of the above-described embodiment of the rotating electric machine (100).

[0046] The rotating electric machine (100) comprises: a stator (2) having a cylindrical stator outer peripheral portion (21); and a flow path forming body (4) provided in contact with a stator outer peripheral surface (21A) of the stator outer peripheral portion (21), and having a flow path (4R) for a heat medium formed therein, wherein a direction perpendicular to the axis of the stator (2) is defined as a radial direction (R), and the flow path forming body (4) comprises a cylindrical inner cylindrical portion (41) in contact with the stator outer peripheral surface (21A), and a cylindrical outer cylindrical portion (42) fitted to the inner cylindrical portion (41) from the outside in the radial direction (R), and the outer cylindrical portion (42) has a lower thermal conductivity than the inner cylindrical portion (41).

[0047] According to this configuration, heat transfer between the inner cylindrical portion (41) and the outer cylindrical portion (42) can be suppressed to a minimum, and heat from the stator (2) is less likely to be transferred to components or other heat-transferable media arranged radially outward (R2) from the outer cylindrical portion (42). Therefore, heat from the stator (2) can be efficiently transferred to the heat medium, making it easier to effectively utilize the heat from the stator (2).

[0048] Here, it is preferable that the rotating electric machine (100) further comprises a case (3) that houses the stator (2), the case (3) comprises a cylindrical outer wall (31) that covers the stator (2) from the outside in the radial direction (R), and a foamed resin (5) is arranged in the gap between the outer peripheral surface (42B) of the outer cylindrical portion (42) and the inner peripheral surface (31A) of the outer peripheral wall (31).

[0049] According to this configuration, the foamed resin (5) absorbs vibrations of the stator (2), reducing vibrations transmitted from the stator (2) to the case (3). This facilitates reducing vibrations and noise transmitted from the case (3) to the outside. Furthermore, this configuration utilizes the insulating properties of the foamed resin (5), minimizing heat transfer between the inner cylindrical portion (41) and the case (3).

[0050] It is also preferable that the foamed resin (5) is arranged in a partial area of ​​the entire area of ​​the outer peripheral surface (42B) of the outer tubular portion (42), and that a gap (5A) is formed in the remaining area between the outer peripheral surface (42B) of the outer tubular portion (42) and the inner peripheral surface (31A) of the outer peripheral wall (31).

[0051] According to this configuration, by adjusting the positional relationship and ratio between the area where the foamed resin (5) is arranged and the area where the void (5A) is formed, the dynamic deformation characteristics of the stator (2), flow path forming body (4), and case (3) can be adjusted, making it easier to reduce vibrations and noise transmitted from the case (3) to the outside.

[0052] Furthermore, it is preferable that the direction along the axis of the stator (2) is defined as an axial direction (X), the region in the axial direction (X) where the stator outer peripheral surface (21A) exists is defined as a stator outer peripheral surface existing region (A1), and both the inner cylindrical portion (41) and the outer cylindrical portion (42) are arranged over the entire area of ​​the stator outer peripheral surface existing region (A1) in the axial direction (X).

[0053] According to this configuration, heat transfer between the inner cylindrical portion (41) and the outer cylindrical portion (42) can be suppressed to a minimum, and heat from the stator (2) is less likely to be transferred to components or other heat-transferable media arranged radially outward (R2) from the outer cylindrical portion (42). Therefore, heat from the stator (2) can be efficiently transferred to the heat medium.

[0054] It is also preferable that the outer peripheral wall (31) is made of metal, the inner cylindrical portion (41) is made of metal, and the outer cylindrical portion (42) is made of fiber-reinforced resin.

[0055] According to this configuration, since the outer cylindrical portion (42) is made of fiber-reinforced resin, heat transfer between the inner cylindrical portion (41) and the case (3) can be reduced, and the rigidity of the flow path forming body (4) can be ensured.

[0056] It is also preferable that the outer cylindrical portion (42) has higher rigidity than the inner cylindrical portion (41).

[0057] According to this configuration, it is possible to reduce vibrations transmitted from the stator (2) to the case (3).

[0058] The technology according to the present disclosure can be used in a rotating electric machine that transfers heat to a heat medium.

[0059] 100: rotating electric machine, 2: stator, 3: case, 4: flow path forming body, 4R: flow path, 5: foamed resin, 5A: gap, 21: stator outer periphery, 21A: stator outer periphery surface, 31: outer periphery wall, 31A: inner periphery surface, 41: inner cylindrical portion, 41A: outer periphery surface, 42: outer cylindrical portion, 42A: inner periphery surface, 42B: outer periphery surface, A1: stator outer periphery surface presence area, R: radial direction, X: axial direction

Claims

1. A rotating electric machine comprising: a stator having a cylindrical outer periphery; and a flow path former provided in contact with the outer periphery of the stator and having a flow path for a heat medium formed therein, wherein the flow path former comprises a cylindrical inner cylindrical portion in contact with the outer periphery of the stator and a cylindrical outer cylindrical portion fitted onto the inner cylindrical portion from the outside in the radial direction, with a direction perpendicular to the axis of the stator being the radial direction; and wherein the outer cylindrical portion has a lower thermal conductivity than the inner cylindrical portion.

2. A rotating electric machine as described in claim 1, further comprising a case for accommodating the stator, the case having a cylindrical outer wall that covers the stator from the outside in the radial direction, and foamed resin disposed in the gap between the outer peripheral surface of the outer cylindrical portion and the inner peripheral surface of the outer peripheral wall.

3. A rotating electric machine as described in claim 2, wherein the foamed resin is arranged in a partial area of ​​the entire area of ​​the outer peripheral surface of the outer cylindrical portion, and in the remaining area, a gap is formed between the outer peripheral surface of the outer cylindrical portion and the inner peripheral surface of the outer peripheral wall.

4. A rotating electric machine as described in claim 1 or 2, wherein the direction along the axis of the stator is defined as the axial direction, the axial region in which the stator outer surface exists is defined as the stator outer surface existing region, and both the inner cylindrical portion and the outer cylindrical portion are arranged across the entire stator outer surface existing region in the axial direction.

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