Rotor shaft, rotor assembly and motor

Abstract

The utility model relates to a rotor shaft, a rotor assembly comprising the rotor shaft and a motor comprising the rotor assembly. The rotor shaft comprises a hollow cylindrical body (1), an oil inlet end (2) located on one axial side of the hollow cylindrical body, a plurality of first oil guide holes (4) and a plurality of second oil guide holes (5). The hollow cylindrical body defines a cavity (11) through which cooling oil flows. The oil inlet end defines an oil supply channel (21) which extends axially and is communicated with the cavity. The first oil guide holes are annularly formed in the first end (12), close to the oil inlet end, of the hollow cylindrical body. And the plurality of second oil guide holes are annularly formed in a second end part (13), far away from the oil inlet end, of the hollow cylindrical body. And the total flow area of the plurality of first oil guide holes is smaller than that of the plurality of second oil guide holes. According to the rotor shaft provided by the utility model, the quantity of cooling oil thrown out from the first oil guide hole and the second oil guide hole at the two ends of the rotor shaft can be uniformly distributed under the condition of specific input flow.

Description

Technical Field

[0001] The utility model relates to the technical field of motors, and more specifically, to a rotor shaft, a rotor assembly comprising the rotor shaft, and a motor comprising the rotor assembly. Background Art

[0002] The main components of the motor include the stator assembly and the rotor assembly. The stator assembly usually includes a stator core and a stator winding, and the rotor assembly usually includes a rotor shaft, a rotor core and a rotor winding or a permanent magnet. When current passes through the stator winding, a rotating magnetic field is generated in the stator core, which induces a rotor magnetic field in the rotor winding and causes the rotor assembly to rotate, thereby converting electrical energy into mechanical energy. The motor generates a lot of heat during operation, and the various components of the motor need to be cooled to ensure the performance and efficiency of the motor.

[0003] It is known in the prior art that oil cooling can be used to cool the motor. For example, during the operation of the motor, cooling oil enters the inner cavity of the rotor shaft from one end of the hollow rotor shaft, and when the rotor shaft rotates, the cooling oil in the inner cavity of the rotor shaft is thrown onto the stator winding or the rotor core through the oil guide hole on the rotor shaft, thereby cooling the stator winding and / or the rotor core. Utility Model Content

[0004] For the aforementioned motor oil cooling structure, since the cooling oil enters the inner cavity of the rotor shaft from one end of the rotor shaft, the pressure at different axial positions in the rotor shaft is different, resulting in different oil output at both ends of the rotor shaft. Specifically, the oil pressure on the side close to the oil inlet end of the rotor shaft is larger, and the amount of oil thrown out through the oil guide hole is larger, while the oil pressure on the side away from the oil inlet end is smaller, and the amount of oil thrown out through the oil guide hole is smaller. Due to the large difference in the oil output through the oil guide hole at both ends of the rotor shaft, the stator winding or the rotor core cannot be evenly cooled, thereby affecting the overall performance of the motor.

[0005] In view of this, the purpose of the utility model is to provide a rotor shaft oil guide hole design scheme that can achieve uniform distribution of oil output.

[0006] To achieve the above-mentioned object, according to one aspect of the utility model, a rotor shaft is provided, the rotor shaft comprising a hollow cylindrical body, an oil inlet end located on one axial side of the hollow cylindrical body, a plurality of first oil guide holes and a plurality of second oil guide holes. The hollow cylindrical body defines a cavity for cooling oil to flow through. The oil inlet end defines an oil supply channel extending axially and communicating with the cavity. The plurality of first oil guide holes are arranged at a first end of the hollow cylindrical body close to the oil inlet end. The plurality of second oil guide holes are arranged at a second end of the hollow cylindrical body away from the oil inlet end. The total flow area of ​​the plurality of first oil guide holes is smaller than the total flow area of ​​the plurality of second oil guide holes.

[0007] According to an embodiment of the present utility model, each of the first oil guide holes and / or each of the second oil guide holes extends in a radial direction of the hollow cylindrical body.

[0008] According to an embodiment of the present utility model, the diameter of the first oil guide hole is smaller than the diameter of the second oil guide hole.

[0009] According to an embodiment of the present utility model, the diameter of the first oil guide hole is 2 mm to 3 mm, and the diameter of the second oil guide hole is 3 mm to 4 mm.

[0010] According to an embodiment of the present utility model, the diameter of the first oil guide hole is 2.5 mm, and the diameter of the second oil guide hole is 3.5 mm.

[0011] According to an embodiment of the present utility model, the number of the first oil guide holes is less than or equal to the number of the second oil guide holes.

[0012] According to an embodiment of the present utility model, the number of the first oil guide holes and the number of the second oil guide holes are 4 to 8 respectively.

[0013] According to an embodiment of the present utility model, the number of the first oil guide holes and the number of the second oil guide holes are both 4.

[0014] According to an embodiment of the present utility model, the plurality of first oil guide holes and / or the plurality of second oil guide holes are arranged at equal intervals along the circumference of the hollow cylindrical body.

[0015] According to an embodiment of the present utility model, the rotor shaft further includes an oil outlet end located at the other axial side of the hollow cylindrical body.

[0016] According to one embodiment of the utility model, the oil outlet end includes an inner end portion located in the cavity and abutting against the inner circumferential wall of the hollow cylindrical body and an outer end portion extending outside the cavity, wherein the end surface of the inner end portion is located between the second oil guide hole and the other axial side of the hollow cylindrical body and close to the second oil guide hole.

[0017] According to an embodiment of the present invention, the inner end portion and the inner peripheral wall form a step-like structure, and the end surface of the inner end portion extends perpendicularly to the axial direction, so that the step-like structure has a vertical riser surface.

[0018] According to one embodiment of the utility model, the oil outlet end defines an oil outlet channel extending axially and connected to the cavity for cooling oil to flow out of the cavity, and the flow area of ​​the oil outlet channel is larger than the flow area of ​​the oil supply channel.

[0019] According to an embodiment of the present utility model, the bottom of the oil outlet channel is lower than the bottom of the oil supply channel.

[0020] According to an embodiment of the present utility model, the oil inlet end is constructed such that its inner wall includes an extension section extending in a direction parallel to the inner circumferential wall of the hollow cylindrical body near the first oil guide hole.

[0021] According to another aspect of the present invention, a rotor assembly is provided. The rotor assembly includes a rotor and the rotor shaft as described above. The rotor is fixed on the rotor shaft between the first oil guide hole and the second oil guide hole.

[0022] According to another aspect of the utility model, a motor is provided, which includes a stator assembly and a rotor assembly as described above, wherein the stator assembly is arranged around the rotor assembly and includes a stator core and a stator winding installed on the stator core, wherein two axial ends of the stator winding respectively extend out of the stator core, and the first oil guide hole and the second oil guide hole are respectively arranged at positions corresponding to the two axial ends of the stator winding.

[0023] The rotor shaft of the utility model is able to achieve uniform distribution of the amount of cooling oil thrown out through the first oil guide holes and the second oil guide holes at both ends of the rotor shaft under a specific input flow rate by setting the total flow area of ​​the multiple first oil guide holes close to the oil inlet end to be smaller than the total flow area of ​​the multiple second oil guide holes far from the oil inlet end. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The features and advantages of the present invention will be clearly understood through the detailed description provided below with reference to the accompanying drawings. It should be understood that the following drawings are merely schematic and not necessarily drawn to scale, and thus cannot be regarded as limiting the present invention, wherein:

[0025] Figure 1 A cross-sectional view of a rotor shaft according to an exemplary embodiment of the present invention is shown.

[0026] Figure 2 Show Figure 1 A perspective view of the rotor shaft is shown.

[0027] Figure 3 An enlarged view showing the vicinity of the connection between the first end portion of the hollow cylindrical body and the oil inlet end.

[0028] Description of reference numerals:

[0029] 1. Hollow cylindrical body; 11. Cavity; 12. First end; 13. Second end; 14. Inner circumferential wall; 15. Outer circumferential wall; 2. Oil inlet end; 21. Oil supply channel; 22. Extended section; 3. Oil outlet end; 31. Inner end; 32. Outer end; 33. Oil outlet channel; 4. First oil guide hole; 5. Second oil guide hole. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, many specific details are set forth so that those skilled in the art can more fully understand and implement the present invention. However, it is obvious to those skilled in the art that the implementation of the present invention may not have some of these specific details. In addition, it should be understood that the present invention is not limited to the specific embodiments described. On the contrary, any combination of the features and elements described below may be considered to implement the present invention, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims unless clearly stated in the claims.

[0031] In the following, terms such as "first", "second", etc. are used to describe the elements of the present application. These terms are only used to distinguish the various elements, and are not used to limit the nature, order or number of these elements. The terms "including" and "having" are used to express an open-ended inclusive meaning, and mean that there may be additional elements / components in addition to the listed elements / components.

[0032] Figure 1 and Figure 2 FIG. 2 shows a rotor shaft according to an embodiment of the present utility model. Figure 1 and Figure 2 As shown, the rotor shaft according to this embodiment includes a hollow cylindrical body 1, an oil inlet end 2, an oil outlet end 3, a plurality of first oil guide holes 4 and a plurality of second oil guide holes 5. The hollow cylindrical body 1 defines a cavity 11 for cooling oil to flow through. The oil inlet end 2 is located at the axial first side ( Figure 1 and Figure 2 The oil inlet end 2 defines an oil supply passage 21. The oil supply passage 21 extends along the axial direction of the hollow cylindrical body 1 and communicates with the cavity 11, so that cooling oil can enter the cavity 11 through the oil supply passage 21. A plurality of first oil guide holes 4 are arranged at intervals along the circumference of the hollow cylindrical body 1 at the first end 12 ( Figure 1 and Figure 2 A plurality of second oil guide holes 5 are arranged at intervals along the circumference of the hollow cylindrical body 1 at the second end 13 of the hollow cylindrical body 1 ( Figure 1 and Figure 2 The right end of the hollow cylindrical body 1 close to the oil outlet end 3, i.e., away from the oil inlet end 2, is shown. When the rotor shaft rotates, the cooling oil flows from one side of the first end 12 to one side of the second end 13, and is thrown out of the hollow cylindrical body 1 through the first oil guide hole 4 and the second oil guide hole 5.

[0033] In this embodiment, the two axial ends of the stator winding (not shown) extend out of the stator core (not shown), respectively, and the rotor (not shown) is fixed to the portion of the rotor shaft corresponding to the first oil guide hole 4 and the second oil guide hole 5 and is arranged corresponding to the stator core. The cooling oil thrown out through the first oil guide hole 4 can cool the first axial end of the stator winding, and the cooling oil thrown out through the second oil guide hole 5 can cool the second axial end of the stator winding. In other embodiments, the cooling oil thrown out through the first oil guide hole 4 and / or the second oil guide hole 5 can also be used to cool the axial end of the rotor core (not shown).

[0034] The pressure of the cooling oil at the first end 12 is greater than that at the second end 13. Therefore, in this embodiment, the total flow area of ​​the plurality of first oil guide holes 4 is designed to be smaller than the total flow area of ​​the plurality of second oil guide holes 5, so that the total amount of cooling oil thrown out through the plurality of first oil guide holes 4 can be substantially the same as the total amount of cooling oil thrown out through the plurality of second oil guide holes 5. Thus, under the condition of a specific input flow rate of cooling oil through the oil supply channel 21, the purpose of evenly distributing the oil output at the first end 12 and the second end 13 of the hollow cylindrical body 1 is achieved.

[0035] Continue to refer Figure 1 The hollow cylindrical body 1 has an inner peripheral wall 14 and an outer peripheral wall 15, and the first oil guide hole 4 and the second oil guide hole 5 are both penetrated from the inner peripheral wall 14 to the outer peripheral wall 15. Depending on the position of the component to be cooled (rotor core or stator winding), the first oil guide hole 4 and the second oil guide hole 5 can also extend from the inner peripheral wall 14 to the outer peripheral wall 15 in an inclined manner toward or away from the oil inlet end 2 or the oil outlet end 3, respectively, but preferably extend in the radial direction of the hollow cylindrical body 1.

[0036] In order to make the total flow area of ​​the plurality of first oil guide holes 4 smaller than the total flow area of ​​the plurality of second oil guide holes 5, according to one embodiment, the aperture of the first oil guide hole 4 close to the oil inlet end can be designed to be smaller than the aperture of the second oil guide hole 5 far from the oil inlet end, which is conducive to making the oil output at each first oil guide hole 4 and the oil output at each second oil guide hole 5 substantially the same, so that the cooling efficiency at the two axial ends of the stator winding is substantially the same. Preferably, the aperture of the first oil guide hole 4 can be 2mm to 3mm, and the aperture of the second oil guide hole 5 can be 3mm to 4mm. Further, the results of the simulation experiment conducted by the inventor show that when the aperture of the first oil guide hole 4 is 2.5mm and the aperture of the second oil guide hole 5 is 3.5mm, the cooling oil is evenly distributed at the first end 12 and the second end 13 of the hollow cylindrical body 1 through the first oil guide hole 4 and the second oil guide hole 5 The effect is best. It can be understood that when the aperture of the first oil guiding holes 4 is smaller than the aperture of the second oil guiding holes 5 , the number of the first oil guiding holes 4 may be equal to the number of the second oil guiding holes 5 .

[0037] In order to make the total flow area of ​​the plurality of first oil guide holes 4 smaller than the total flow area of ​​the plurality of second oil guide holes 5, according to another embodiment, the number of the first oil guide holes 4 may be designed to be smaller than the number of the second oil guide holes 5. It is understandable that when the number of the first oil guide holes 4 is smaller than the number of the second oil guide holes 5, the aperture of the first oil guide hole 4 may be equal to the aperture of the second oil guide hole 5.

[0038] According to another embodiment, the aperture of the first oil guide hole 4 may be smaller than the aperture of the second oil guide hole 5, and the number of the first oil guide holes 4 may be smaller than the number of the second oil guide holes 5. For example, when the pressure difference of the cooling oil at the first oil guide hole 4 and the second oil guide hole 5 is small, the flow balance distribution can be achieved only by designing the aperture or the number of the oil guide holes; and when the pressure difference of the cooling oil at the first oil guide hole 4 and the second oil guide hole 5 is large, the flow balance distribution can be achieved by designing both the aperture and the number of the oil guide holes.

[0039] The number of the first oil guide holes 4 and the second oil guide holes 5 can be 4 to 8. That is, 4 to 8 first oil guide holes 4 are arranged at the first end 12 close to the oil inlet end 2, and 4 to 8 second oil guide holes 5 are arranged at the second end 13 away from the oil inlet end 2. When the rotor shaft rotates, a part of the cooling oil supplied from the oil supply channel 21 to the cavity 11 is thrown to the first axial end of the stator winding via the 4 to 8 first oil guide holes 4 to cool it, and another part of the cooling oil continues to flow along the axial direction of the rotor shaft and can be thrown to the second axial end of the stator winding via the 4 to 8 second oil guide holes 5 to cool it. The setting of 4 to 8 first oil guide holes 4 and second oil guide holes 5 reduces the processing cost and difficulty, and improves the strength and life of the rotor shaft. The number of the first oil guide holes 4 and the second oil guide holes 5 can be specifically set according to the size of the stator winding or the rotor core to be cooled. Preferably, the number of the first oil guide holes 4 and the second oil guide holes 5 is 4.

[0040] Further preferably, a plurality of first oil guide holes 4 are arranged at equal intervals along the circumference of the hollow cylindrical body 1, and / or a plurality of second oil guide holes 5 are arranged at equal intervals along the circumference of the hollow cylindrical body 1. Thus, on the one hand, the two axial ends of the rotor core or the stator winding can be cooled more evenly, and on the other hand, the rotor shaft can maintain dynamic balance during rotation to prevent it from deflecting. It is understandable that in some cases, the dynamic balance in the rotor shaft can also be adjusted by arranging the first oil guide holes 4 and / or the second oil guide holes 5 in a non-equally spaced manner.

[0041] In this embodiment, if Figure 1 As shown, the rotor shaft also includes an axial second side ( Figure 1 and Figure 2 The oil outlet end 3 is arranged opposite to the oil inlet end 2. The oil outlet end 3 includes an inner end 31 located in the cavity 11 and abutting against the inner peripheral wall 14 of the hollow cylindrical body 1 and an outer end 32 extending outside the cavity 11. The end surface of the inner end 31 is located between the second oil guide hole 5 and the axial second side of the hollow cylindrical body 1 and close to the second oil guide hole 5. Due to the blocking of the cooling oil by the end surface of the inner end 31, compared with the case where such an end surface is not arranged near the second oil guide hole 5, the amount of cooling oil thrown out of the rotor shaft through the second oil guide hole 5 according to this embodiment can be greater.

[0042] The inner end portion 31 forms a step-like structure with the inner peripheral wall 14 of the hollow cylindrical body 1. The end face of the inner end portion 31 extends perpendicularly to the axial direction, so that the step-like structure has a vertical kick surface. Especially in the case of high speed, a very thin (for example, a few tenths of a millimeter) oil film will be formed along the inner peripheral wall 14 of the hollow cylindrical body 1. At this time, the cooling oil will be blocked by the end face of the inner end portion 31 to form a reflux, which increases the resistance to flow along the inner peripheral wall 14, thereby improving the oil discharge effect of the first oil guide hole 4 and the second oil guide hole 5.

[0043] like Figure 1 As shown, the oil outlet end 3 may define an oil outlet channel 33 extending axially and communicating with the cavity 11 for cooling oil to flow out of the cavity 11. The oil outlet channel 33 may include a plurality of sections, the inner diameter of which decreases sequentially from the inner end 31 toward the outer end 32 of the oil outlet end 3. Preferably, the flow area of ​​the oil outlet channel 33 is greater than the flow area of ​​the oil supply channel 21. Further preferably, the bottom of the oil outlet channel 33 is lower than the bottom of the oil supply channel 21.

[0044] At low speeds, the cooling oil is basically unable to be thrown out from the first oil guide hole 4 and the second oil guide hole 5 by centrifugal force. By providing the oil outlet end 3 with an opening, namely the oil outlet channel 33, the cooling oil and gas in the cavity 11 can be discharged at low speeds, and the pressure in the cavity 11 can be kept stable, so that the cooling oil can continue to enter the cavity 11. In addition, by making the flow area of ​​the oil outlet channel 33 larger than the flow area of ​​the oil supply channel 21, especially making the bottom of the oil outlet channel 33 lower than the bottom of the oil supply channel 21, it is more conducive to the outflow of the cooling oil at low speeds.

[0045] It is understandable that, in other embodiments, the oil outlet end 3 may also be a closed solid structure for sealing the hollow cylindrical body 1 so that the cooling oil can only flow out from the first oil guide hole 4 and the second oil guide hole 5 .

[0046] Preferably, the oil inlet end 2 is configured such that its inner wall includes an extension section 22 extending in a direction parallel to the inner peripheral wall 14 of the hollow cylindrical body 1 near the first oil guide hole 4, such as Figure 3 This guides part of the cooling oil into the cavity 11 (not out of the first oil guide hole 4), so that the oil output at both ends of the rotor shaft is more balanced.

[0047] Table 1 below shows the simulation results for an exemplary rotor shaft. The outer diameter of the hollow cylindrical body 1 of the rotor shaft is 61.92 mm, the inner diameter is 49.925 mm, four first oil guide holes 4 with a diameter of 2.5 mm are evenly distributed along the circumference at the first end 12 near the oil inlet end 2, four second oil guide holes 5 with a diameter of 3.5 mm are evenly distributed along the circumference at the first end 13 near the oil outlet end 3, and the axial spacing between the first oil guide holes 4 and the second oil guide holes 5 is 115 mm. The simulation results show that when the mass flow rate (oil inlet amount) at the oil supply channel 21 is 50.14 g / s, the mass flow rate and oil outlet ratio at the first oil guide holes 4 and the second oil guide holes 5 when the rotor shaft speed is 6000 rpm, 12500 rpm, and 16000 rpm respectively.

[0048] Table 1

[0049]

[0050]

[0051] It can be seen from the simulation results shown in Table 1 that by setting the apertures of the oil guide holes at both ends of the rotor shaft to be different and coordinating with other structures of the rotor shaft, it is possible to achieve a basically uniform distribution of the cooling oil at both ends of the rotor shaft (even at high speeds).

[0052] The utility model also provides a rotor assembly including a rotor and the rotor shaft. The rotor can be fixed on the rotor shaft between the first oil guide hole 4 and the second oil guide hole 5. Rotor end plates can be respectively provided at both ends of the rotor, and oil guide groove structures respectively connected to the first oil guide hole 4 and the second oil guide hole 5 can be formed on the rotor end plates to further promote the cooling oil to be directed to the components to be cooled.

[0053] The utility model also provides a motor including a stator assembly and the above-mentioned rotor assembly. The stator assembly can be arranged around the rotor assembly and includes a stator core and a stator winding installed on the stator core. Two axial ends of the stator winding can extend out of the stator core respectively, and the first oil guide hole 4 and the second oil guide hole 5 can be respectively arranged at positions corresponding to the two axial ends of the stator winding.

[0054] For those skilled in the art, various modifications and variations may be made to the embodiments disclosed above without departing from the scope or spirit of the utility model. Other embodiments of the utility model will be apparent to those skilled in the art from the practice of the utility model disclosed in this specification. This specification and the examples disclosed therein should be considered to be illustrative only, and the true scope of the utility model is specified by the appended claims and their equivalents.

Claims

1. A rotor shaft, characterized in that: include: A hollow cylindrical body (1), wherein the hollow cylindrical body (1) defines a cavity (11) for cooling oil to flow through; An oil inlet end (2) located on one axial side of the hollow cylindrical body (1), the oil inlet end (2) defining an oil supply passage (21) extending axially and communicating with the cavity (11); A plurality of first oil guide holes (4), the plurality of first oil guide holes (4) being arranged in a ring at a first end portion (12) of the hollow cylindrical body (1) close to the oil inlet end (2); as well as A plurality of second oil guide holes (5), the plurality of second oil guide holes (5) being arranged in a ring at a second end portion (13) of the hollow cylindrical body (1) away from the oil inlet end (2); Wherein, the total flow area of ​​the plurality of first oil guide holes (4) is smaller than the total flow area of ​​the plurality of second oil guide holes (5).

2. The rotor shaft according to claim 1, characterized in that Each of the first oil guide holes (4) and / or each of the second oil guide holes (5) extends in the radial direction of the hollow cylindrical body (1).

3. The rotor shaft according to claim 1 or 2, characterized in that: The diameter of the first oil guide hole (4) is smaller than the diameter of the second oil guide hole (5).

4. The rotor shaft according to claim 3, characterized in that The diameter of the first oil guide hole (4) is 2 mm to 3 mm, and the diameter of the second oil guide hole (5) is 3 mm to 4 mm.

5. The rotor shaft according to claim 3, characterized in that The diameter of the first oil guide hole (4) is 2.5 mm, and the diameter of the second oil guide hole (5) is 3.5 mm.

6. The rotor shaft according to claim 1 or 2, characterized in that: The number of the first oil guide holes (4) is less than or equal to the number of the second oil guide holes (5).

7. The rotor shaft according to claim 1 or 2, characterized in that: The number of the first oil guide holes (4) and the number of the second oil guide holes (5) are respectively 4 to 8.

8. The rotor shaft according to claim 7, characterized in that The number of the first oil guide holes (4) and the number of the second oil guide holes (5) are both four.

9. The rotor shaft according to claim 1 or 2, characterized in that: The plurality of first oil guide holes (4) and / or the plurality of second oil guide holes (5) are arranged at equal intervals along the circumference of the hollow cylindrical body (1).

10. The rotor shaft according to claim 1 or 2, characterized in that The rotor shaft further comprises an oil outlet end (3) located at the other axial side of the hollow cylindrical body (1).

11. The rotor shaft according to claim 10, characterized in that The oil outlet end (3) comprises an inner end portion (31) located in the cavity (11) and abutting against the inner circumferential wall (14) of the hollow cylindrical body (1), and an outer end portion (32) extending outside the cavity (11), wherein an end surface of the inner end portion (31) is located between the second oil guide hole (5) and the other axial side of the hollow cylindrical body (1) and close to the second oil guide hole (5).

12. The rotor shaft according to claim 11, characterized in that The inner end portion (31) and the inner peripheral wall (14) form a step-like structure, and the end surface of the inner end portion (31) extends perpendicularly to the axial direction, so that the step-like structure has a vertical riser surface.

13. The rotor shaft according to claim 10, characterized in that The oil outlet end (3) defines an oil outlet channel (33) extending axially and communicating with the cavity (11) for allowing cooling oil to flow out of the cavity (11); a flow area of ​​the oil outlet channel (33) is greater than a flow area of ​​the oil supply channel (21).

14. The rotor shaft according to claim 13, characterized in that The bottom of the oil outlet channel (33) is lower than the bottom of the oil supply channel (21).

15. The rotor shaft according to claim 1 or 2, characterized in that The oil inlet end (2) is constructed such that its inner wall includes an extended section extending in a direction parallel to the inner peripheral wall (14) of the hollow cylindrical body (1) near the first oil guide hole (4).

16. A rotor assembly, characterized in that: The invention comprises a rotor and a rotor shaft according to any one of claims 1 to 15, wherein the rotor is fixed on the rotor shaft between the first oil guide hole (4) and the second oil guide hole (5).

17. A motor, characterized in that: The invention comprises a stator assembly and a rotor assembly according to claim 16, wherein the stator assembly is arranged around the rotor assembly and comprises a stator core and a stator winding installed on the stator core, wherein two axial ends of the stator winding respectively extend out of the stator core, and the first oil guide hole (4) and the second oil guide hole (5) are respectively arranged at positions corresponding to the two axial ends of the stator winding.

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