rotor

Abstract

This invention relates to a rotor. The rotor comprises: a rotor shaft extending axially; and a rotor core fixed to the outer peripheral surface of the rotor shaft, having a plurality of magnet holes extending axially. Cooling pipes and at least one magnet are respectively disposed in the plurality of magnet holes. The cooling pipes extend axially and have internal paths for refrigerant flow.

Description

Technical Field

[0001] The technology disclosed in this specification relates to the rotor of an electric motor. Background Technology

[0002] Japanese Patent No. 5120538 describes a rotor for an electric motor. This rotor includes a rotor shaft extending axially and a rotor core fixed to the outer circumferential surface of the rotor shaft. The rotor core has multiple magnet holes, each containing a magnet. Furthermore, for each of the multiple magnet holes, a space is formed axially to allow refrigerant to flow along the magnet.

[0003] As described above, in order for the refrigerant to flow through the magnet hole, a space needs to be provided inside the magnet hole to serve as a path for the refrigerant. However, if there is space inside the magnet hole, there is a problem that the fixing strength of the magnet relative to the magnet hole will be reduced. Summary of the Invention

[0004] This specification provides the following techniques for securely fixing a magnet to a magnet hole and allowing refrigerant to flow inside the magnet hole.

[0005] The technology disclosed in this specification is specifically embodied in the rotor of an electric motor. In this first embodiment, the rotor includes: a rotor shaft extending axially; and a rotor core fixed to the outer peripheral surface of the rotor shaft, and having a plurality of magnet holes extending axially. Cooling pipes and at least one magnet are respectively disposed in the plurality of magnet holes. The cooling pipes extend axially and have internal paths for refrigerant flow.

[0006] In the above configuration, a cooling pipe is disposed inside the magnet hole, and a path for refrigerant to flow is formed inside the cooling pipe. With this configuration, since the cooling pipe has a certain rigidity, even if a space is formed inside it, the decrease in the fixing strength of the magnet relative to the magnet hole can be prevented.

[0007] In the second embodiment, according to the first embodiment described above, at least one magnet and the cooling pipe can be fixed to the magnet hole by a filler material filled within the magnet hole. With this configuration, at least one magnet and the cooling pipe can be securely fixed to the magnet hole.

[0008] In the third approach, based on the second approach described above, the filler material may also be composed of resin. Resin has electrical insulation properties and excellent formability.

[0009] In the fourth embodiment, according to any of the first to third embodiments described above, the at least one magnet may include a first magnet and a second magnet. In this case, the cooling pipe may extend along the axial direction between the first magnet and the second magnet. With this configuration, the first magnet and the second magnet disposed in the same magnet hole can be effectively cooled.

[0010] In the fifth embodiment, based on the fourth embodiment described above, the cooling pipes can also be in direct contact with both the first magnet and the second magnet. With this configuration, the first magnet and the second magnet can be cooled more effectively.

[0011] In the sixth embodiment, according to any of the first to fifth embodiments described above, the cooling pipe may be made of a material with electrical insulation properties. With this configuration, eddy current losses can be avoided in the cooling pipe.

[0012] In the seventh embodiment, according to any of the first to sixth embodiments described above, the rotor core may have a first end face and a second end face, the rotor core extending axially from the first end face to the second end face. In this case, the cooling pipe may extend from the first end face to the second end face of the rotor core. With this configuration, the cooling pipe can cover the entire length of the rotor core to cool the magnet.

[0013] In the eighth embodiment, according to the seventh embodiment described above, the rotor may further include a first end plate fixed to the outer circumferential surface of the rotor shaft and disposed adjacent to the first end face of the rotor in the axial direction. In this case, a refrigerant supply path for supplying refrigerant to the cooling pipe may be provided in the first end plate.

[0014] In the ninth embodiment, according to the eighth embodiment described above, a rotor shaft refrigerant path for supplying refrigerant from the outside may be provided on the rotor shaft. In this case, the refrigerant supply path of the first end plate may connect the rotor shaft refrigerant path to the cooling pipe.

[0015] In the tenth embodiment, according to the ninth embodiment described above, the rotor may further include a second end plate fixed to the outer circumferential surface of the rotor shaft and disposed adjacent to the second end face of the rotor in the axial direction. In this case, the second end plate may also be provided with a refrigerant discharge path for discharging refrigerant from the cooling pipe. Attached Figure Description

[0016] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same symbols denote the same parts.

[0017] Figure 1 This is a cross-sectional view schematically illustrating the structure of the electric motor 2 employing the rotor 10 of the embodiment.

[0018] Figure 2 This is a cross-sectional view showing the internal structure of the rotor 10 in an embodiment. Figure 2 In the diagram, arrow F schematically represents the flow of refrigerant.

[0019] Figure 3 yes Figure 2 A cross-sectional view at line III-III.

[0020] Figure 4 yes Figure 3 Enlarged view of part IV. Detailed Implementation

[0021] Referring to the accompanying drawings, the rotor 10 of the embodiment and the electric motor 2 using the rotor 10 will be described. The electric motor 2 can be used, for example, as a prime mover to drive the wheels in an electric vehicle. Electric vehicles, as referred to herein, include battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). The electric motor 2 is a three-phase AC motor. Furthermore, the configuration described in this embodiment is not limited to a three-phase AC motor, and other types of electric motors can also be used.

[0022] In this embodiment, a cylindrical coordinate system D1, D2, and D3 is defined with the rotation axis X of the electric motor 2 as the reference. In the accompanying drawings, direction D1 is parallel to the rotation axis X of the electric motor 2, representing the axial direction in this embodiment. Direction D2 is perpendicular to the rotation axis X, representing the radial direction in this embodiment. Furthermore, direction D3 is perpendicular to both directions D1 and D2, representing the circumferential direction in this embodiment.

[0023] like Figure 1 As shown, the electric motor 2 mainly includes a stator 4, a rotor 10, and a housing 100. The housing 100 houses the stator 4 and the rotor 10. The stator 4 is fixed to the housing 100, and the rotor 10 is supported by the housing 100 to be able to rotate.

[0024] First, the structure of the stator 4 will be described. However, the specific structure of the rotor 10 and stator 4 in this embodiment is not particularly limited. The rotor 10 of this embodiment can be used in combination with stators of various other types.

[0025] Although this is just one example, the stator 4 can also have a stator core 6 and stator coils 8. The stator core 6 has a generally cylindrical shape and is configured to surround the rotor 10. The stator core 6 has a first end face 6a and a second end face 6b in the axial direction. The stator core 6 extends axially from the first end face 6a to the second end face 6b. The stator core 6 is configured to have multiple silicon steel plates (also called electromagnetic steel plates) stacked on top of each other. Multiple slits 6d are formed on the inner circumferential surface 6c of the stator core 6. The multiple slits 6d are arranged at equal intervals in the circumferential direction. The multiple slits 6d extend axially from the first end face 6a of the stator core 6 to the second end face 6b, respectively.

[0026] The stator coils 8 are arranged in multiple slits 6d of the stator core 6. The stator coils 8 are constructed, for example, of wires such as coil segments. The stator coils 8 can also have a distributed winding structure, or a concentrated winding structure is also preferred. Three-phase alternating current is supplied to the stator coils 8 from the outside. When three-phase alternating current is supplied to the stator coils 8, a rotating magnetic field is formed in the internal space of the stator core 6 where the rotor 10 is located.

[0027] Next, the configuration of the rotor 10 in the embodiment will be described. Figure 1 , Figure 3 As shown, the rotor 10 includes a rotor shaft 12, a rotor core 14, and a pair of end plates 16 and 18. The rotor shaft 12 extends along the rotation axis X of the electric motor 2. The rotor shaft 12 is supported by the housing 100 around the rotation axis X and is rotatable. That is, the rotation axis X of the electric motor 2 strictly refers to the rotation axis of the rotor 10. The rotor shaft 12 is made of steel, for example, stainless steel. However, the material of the rotor shaft 12 is not particularly limited. A rotor shaft refrigerant path 20 is provided inside the rotor shaft 12. The rotor shaft refrigerant path 20 will be described in detail later.

[0028] The rotor core 14 is fixed to the outer peripheral surface 12a of the rotor shaft 12. Therefore, the rotor core 14 rotates integrally with the rotor shaft 12. The rotor core 14 has a generally cylindrical shape and is arranged to surround the rotor shaft 12. The rotor core 14 has a first end face 14a and a second end face 14b in the axial direction. The rotor core 14 extends axially from the first end face 14a to the second end face 14b. The rotor core 14 is constructed by stacking multiple silicon steel plates 13 (also called electromagnetic steel plates). However, the material constituting the rotor core 14 is not limited to silicon steel and can also be other types of magnetic materials.

[0029] A pair of end plates 16, 18 are fixed to the outer peripheral surface 12a of the rotor shaft 12. The pair of end plates 16, 18 have a first end plate 16 and a second end plate 18. The first end plate 16 is disposed adjacent to the first end face 14a of the rotor core 14. The second end plate 18 is disposed adjacent to the second end face 14b of the rotor core 14. Thus, the rotor core 14 is axially held by the pair of end plates 16, 18. Although this is an example, each end plate 16, 18 is made of a non-magnetic material such as aluminum alloy. Multiple refrigerant supply paths 60 are provided on the first end plate 16, and multiple refrigerant discharge paths 80 are provided on the second end plate 18. The refrigerant supply paths 60 and the refrigerant discharge paths 80 will be described in detail later.

[0030] Next, refer to Figures 2-4 The internal structure of the rotor core 14 will be described. The rotor core 14 has a plurality of magnet holes 40. The plurality of magnet holes 40 are arranged at equal intervals along the circumference. The plurality of magnet holes 40 extend axially from a first end face 14a of the rotor core 14 to a second end face 14b. Here, the number and arrangement of the plurality of magnet holes 40 are not particularly limited. In addition, the shape and size of the cross-section of each magnet hole 40 are not particularly limited.

[0031] A first magnet 42, a second magnet 44, and a cooling pipe 46 are respectively disposed in multiple magnet holes 40. The first magnet 42 and the second magnet 44 are permanent magnets, such as rare earth magnets. The first magnet 42 and the second magnet 44 extend axially from the first end face 14a of the rotor core 14 to the second end face 14b. The cooling pipe 46 also extends axially from the first end face 14a of the rotor core 14 to the second end face 14b. The cooling pipe 46 is located between the first magnet 42 and the second magnet 44 and is in direct contact with the first magnet 42 and the second magnet 44. Here, the number of magnets 42 and 44 is not particularly limited. At least one magnet is disposed in each of the multiple magnet holes 40.

[0032] The first magnet 42, the second magnet 44, and the cooling pipe 46 are fixed to the magnet hole 40 by a filler material 48 filling the magnet hole 40. Although this is just one example, the filler material 48 is made of resin. The filler material 48 completely fills the gap between the outer surface 42a of the first magnet 42 and the inner surface 40a of the magnet hole 40, the gap between the outer surface 44a of the second magnet 44 and the inner surface 40a of the magnet hole 40, and the gap between the cooling pipe 46 and the inner surface 40a of the magnet hole 40. Thus, the two magnets 42, 44 and the cooling pipe 46 are securely fixed to the magnet hole 40. Here, when manufacturing the rotor 10, after the two magnets 42, 44 and the cooling pipe 46 are placed in the magnet hole 40, the filler material 48 can be formed by injecting molten resin into the gap in the magnet hole 40. However, as another method, the filler material 48 can also be formed by placing foaming resin into the gap in the magnet hole 40 and foaming the foaming resin by heating.

[0033] The cooling pipe 46 is a hollow tube. An axially extending space 47 is formed inside the cooling pipe 46. This space 47 extends from the first end face 14a of the rotor core 14 to the second end face 14b. The space 47 within the cooling pipe 46 functions as a path for the refrigerant to circulate. The refrigerant is not particularly limited, but can be an oil such as lubricating oil. By allowing the refrigerant to circulate within the cooling pipe 46, the first magnet 42 and the second magnet 44 adjacent to the cooling pipe 46 are cooled. In particular, in this embodiment, the cooling pipe 46 is located between the first magnet 42 and the second magnet 44, and is in direct contact with both the first magnet 42 and the second magnet 44. Therefore, the refrigerant circulating within the cooling pipe 46 can effectively cool the first magnet 42 and the second magnet 44.

[0034] There is no particular limitation on the method of supplying refrigerant to the cooling pipe 46. Although this is just one example, in the rotor 10 of this embodiment, refrigerant is supplied to the cooling pipe 46 of each magnet hole 40 via the rotor shaft refrigerant path 20 provided on the rotor shaft 12 and multiple refrigerant supply paths 60 provided on the first end plate 16. For example... Figure 2 As shown, the rotor shaft refrigerant path 20 has a main path 22 extending axially and multiple branch paths 24 extending radially from the main path 22. The multiple branch paths 24 extend to the outer peripheral surface 12a of the rotor shaft 12 and open toward the first end plate 16. On the first end plate 16, multiple refrigerant supply paths 60 extend radially. The multiple refrigerant supply paths 60 connect the multiple branch paths 24 of the rotor shaft 12 to the cooling pipes 46 of the multiple magnet holes 40.

[0035] For example, refrigerant is supplied from the outside of rotor 10 to the refrigerant path 20 of rotor shaft 12 via an oil pump (illustration omitted). Figure 2 As indicated by arrow F, the refrigerant supplied to the rotor shaft refrigerant path 20 flows from the main path 22 to multiple branch paths 24 and into multiple refrigerant supply paths 60 of the first end plate 16. Then, the refrigerant is supplied through the multiple refrigerant supply paths 60 to the cooling pipes 46 of the multiple magnet holes 40. The refrigerant supplied to the cooling pipes 46 flows axially toward the second end face 14b of the rotor core 14.

[0036] As described above, the second end plate 18 is adjacent to the second end face 14b of the rotor core 14. Furthermore, the second end plate 18 is provided with multiple refrigerant discharge paths 80. These multiple refrigerant discharge paths 80 are respectively connected to cooling pipes 46 of multiple magnet holes 40 at the second end face 14b of the rotor core 14. Thus, refrigerant from the cooling pipes 46 is discharged to the outside of the rotor 10. Although this is just one example, the multiple refrigerant discharge paths 80 each extend to the outer peripheral surface 18a of the second end plate 18. With this configuration, the refrigerant discharged from the multiple refrigerant discharge paths 80 can be supplied to the stator coils 8 to cool them.

[0037] As described above, in the rotor 10 of this embodiment, a cooling pipe 46 is disposed within the magnet hole 40, and a path (space 47) for refrigerant flow is formed inside the cooling pipe 46. This allows for direct cooling of the magnets 42 and 44 disposed in the same magnet hole 40. Conventionally, if a path (space) for refrigerant flow is formed inside the magnet hole 40, there is a problem where the fixing strength of the magnets relative to the magnet hole decreases. Regarding this, in the rotor 10 of this embodiment, the path (space 47) for refrigerant flow is formed through the cooling pipe 46. With this configuration, since the cooling pipe 46 has a certain rigidity, even if a space 47 is formed inside it, the decrease in the fixing strength of the magnets 42 and 44 relative to the magnet hole 40 can be suppressed.

[0038] The material constituting the cooling pipe 46 is not particularly limited. Although it is an example, the cooling pipe 46 in this embodiment is made of resin. Furthermore, it is not limited to resin, and the cooling pipe 46 may also be made of a material with electrical insulation properties. With such a configuration, eddy current losses can be avoided in the cooling pipe 46.

[0039] The above provides a detailed description of specific examples of the technology disclosed in this specification, but these are not limited to the examples and do not limit the scope of the technical solution. The technology described within the scope of the technical solution includes various modifications and alterations to the specific examples described above. The technical elements described in this specification or drawings exert their technical usefulness individually or in various combinations, and are not limited to the combinations described in the technical solution at the time of application. Furthermore, the technology illustrated in this specification or drawings can achieve multiple objectives simultaneously, and it is technically useful by achieving only one of these objectives.

Claims

1. A rotor, specifically a rotor for an electric motor. The rotor is characterized by having: Rotor shaft, which extends axially; and The rotor core is fixed to the outer circumferential surface of the rotor shaft and has a plurality of magnet holes, each extending along the axial direction. Each of the plurality of magnet holes is respectively equipped with a cooling pipe and at least one magnet. The cooling pipe extends along the axial direction and has a path inside it for the refrigerant to flow.

2. The rotor according to claim 1, characterized in that, The at least one magnet and the cooling pipe are fixed to the magnet hole by a filler material filled in the magnet hole.

3. The rotor according to claim 2, characterized in that, The filler material is composed of resin.

4. The rotor according to claim 1, characterized in that, The at least one magnet includes a first magnet and a second magnet. The cooling pipe extends along the axial direction between the first magnet and the second magnet.

5. The rotor according to claim 4, characterized in that, The cooling pipe is in direct contact with the first magnet and the second magnet, respectively.

6. The rotor according to claim 1, characterized in that, The cooling pipe is made of an electrically insulating material.

7. The rotor according to claim 1, characterized in that, The rotor core has a first end face and a second end face, and the rotor core extends from the first end face along the axial direction to the second end face. The cooling pipe extends from the first end face of the rotor core to the second end face.

8. The rotor according to claim 7, characterized in that, It also includes a first end plate, which is fixed to the outer peripheral surface of the rotor shaft and is disposed adjacent to the first end face of the rotor in the axial direction. A refrigerant supply path is provided on the first end plate for supplying refrigerant to the cooling pipe.

9. The rotor according to claim 8, characterized in that, The rotor shaft is provided with a rotor shaft refrigerant path for supplying refrigerant from the outside. The refrigerant supply path of the first end plate connects the refrigerant path of the rotor shaft to the cooling pipe.

10. The rotor according to claim 9, characterized in that, It also includes a second end plate, which is fixed to the outer circumferential surface of the rotor shaft and is disposed adjacent to the second end face of the rotor in the axial direction. The second end plate is provided with a refrigerant discharge path for discharging refrigerant from the cooling pipe.

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