Motor rotor, rotor assembly, motor and vehicle

Abstract

The utility model relates to a motor rotor, a rotor assembly, a motor and a vehicle. The motor rotor comprises a rotor core, the rotor core is provided with a rotating shaft mounting hole, the inner wall surface of the rotating shaft mounting hole is provided with a plurality of first oil grooves extending along the axial direction, the plurality of first oil grooves are arranged at intervals along the circumferential direction, and the rotor core is also provided with a plurality of first oil channels extending along the axial direction around the rotating shaft mounting hole. According to the technical scheme, the two layers of cooling oil channels are formed in the rotor, and the design of the two layers of cooling oil channels prolongs the flowing path of cooling oil in the rotor core and prolongs the effective cooling time of the cooling oil in the rotor core, so that the heat dissipation capability of the motor rotor is improved, and the operation reliability of the motor is ensured.

Description

Technical Field

[0001] The present disclosure relates to the technical field of motors, and in particular to a motor rotor, a rotor assembly, a motor and a vehicle. Background Art

[0002] With the continuous development of new energy vehicles and the gradual improvement of their driving capabilities, higher requirements are placed on motor speed, torque density, power density, etc. The higher the motor speed, torque density, and power density, the higher the heat generated. Specifically, when the motor is running at high speed, the motor rotor components generate a lot of heat, which may cause magnetic steel demagnetization and power attenuation in severe cases. Whether it has good heat dissipation performance is crucial for the reliable and stable operation of the motor, so it is necessary to improve the heat dissipation performance of the motor rotor components. Utility Model Content

[0003] In order to overcome the problems existing in the related art, the present disclosure provides a motor rotor, a rotor assembly, a motor and a vehicle.

[0004] According to a first aspect of an embodiment of the present disclosure, a motor rotor is provided, comprising a rotor core, wherein the rotor core is provided with a shaft mounting hole, the inner wall surface of the shaft mounting hole is provided with a plurality of first oil grooves extending axially, the plurality of first oil grooves are arranged at intervals along the circumferential direction, and the rotor core is also provided with a plurality of first oil channels extending axially around the shaft mounting hole.

[0005] Optionally, the rotor core is provided with a plurality of weight-removing holes and magnetic steel holes around the shaft mounting hole, and the weight-removing holes and / or the magnetic steel holes are used as the first oil passages.

[0006] Optionally, a plurality of the first oil grooves are arranged at equal intervals along the circumferential direction.

[0007] Optionally, the inner wall surface of the shaft mounting hole is also provided with a plurality of limit portions at intervals along the circumferential direction, suitable for cooperating with the shaft so that the shaft and the rotor core rotate coaxially, and the plurality of limit portions are staggered with the first oil groove in the circumferential direction.

[0008] According to a second aspect of an embodiment of the present disclosure, a rotor assembly is provided, comprising a rotating shaft and a balancing disk and a motor rotor respectively mounted on the rotating shaft, wherein the motor rotor is any one of the motor rotors described above; the rotating shaft is a hollow rotating shaft and a plurality of oil injection holes are arranged on the circumferential wall; the balancing disk is provided with an oil outlet hole, wherein: a second oil passage is formed between the outer circumferential wall of the rotating shaft and the first oil groove, the oil injection hole is connected to the second oil passage, the second oil passage is connected to the first oil passage, and the first oil passage is connected to the oil outlet hole.

[0009] Optionally, the oil injection hole is arranged at a middle position of the rotating shaft along the axial direction.

[0010] Optionally, the balancing plate is provided with a second oil groove and a third oil groove, wherein the second oil groove is connected to the second oil channel, and the third oil groove is respectively connected to the second oil groove and the first oil channel, and there are multiple oil outlet holes, and the multiple oil outlet holes are arranged around the second oil groove at intervals and staggered with the third oil groove, wherein the two balancing plates arranged at both ends of the motor rotor are configured so that the third oil groove of one of them corresponds to the position of the oil outlet hole of the other one.

[0011] Optionally, the two balancing plates at both ends have the same structure, and the number of the third oil grooves and the oil outlet holes on each balancing plate is equal and is half of the first oil channel.

[0012] Optionally, the second oil groove is configured in an annular shape, and a plurality of the third oil grooves are arranged at intervals along the circumference of the second oil groove, and the plurality of third oil grooves all extend radially outward from the second oil groove.

[0013] According to a third aspect of an embodiment of the present disclosure, there is provided an electric motor comprising a rotor assembly according to any one of the above items.

[0014] According to a fourth aspect of an embodiment of the present disclosure, a vehicle is provided, comprising the above-mentioned motor.

[0015] The technical solution provided by the embodiments of the present disclosure may include the following beneficial effects: the motor rotor provided by the present disclosure is provided with a plurality of first oil grooves extending in the axial direction on the inner wall surface of the shaft mounting hole, and the plurality of first oil grooves are arranged at intervals in the circumferential direction, and a plurality of first oil channels extending in the axial direction are also provided around the shaft mounting hole. After the motor rotor provided by the present disclosure is installed on the shaft, a second oil channel can be formed between the outer peripheral wall of the shaft and the first oil groove, and the second oil channel is connected to the first oil channel, so that the cooling oil entering the motor rotor flows through the second oil channel and the first oil channel in sequence, that is, two layers of cooling oil channels are formed inside the motor rotor. The design of the two layers of cooling oil channels prolongs the flow path and effective cooling time of the cooling oil inside the motor rotor, which is beneficial to improving the heat dissipation capacity of the motor rotor and ensuring the reliability of the motor operation.

[0016] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0018] Figure 1is a schematic structural diagram of an electronic rotor according to an exemplary embodiment.

[0019] Figure 2 It is a schematic structural diagram of a rotor assembly according to an exemplary embodiment.

[0020] Figure 3 is a cross-sectional view of a rotor assembly according to an exemplary embodiment.

[0021] Figure 4 The figure is a schematic structural diagram of a balancing disk shown in an exemplary embodiment.

[0022] Figure 5 is a schematic diagram showing a cooling path according to an exemplary embodiment.

[0023] Description of Reference Numerals

[0024] 1-rotor core, 11-shaft mounting hole, 12-first oil groove, 13-first oil channel, 131-weight removal hole, 132-magnetic steel hole, 14-limiting part, 15-magnetic steel, 16-second oil channel, 2-shaft, 21-oil injection hole, 3-balancing plate, 31-second oil groove, 32-third oil groove, 33-oil outlet hole. DETAILED DESCRIPTION

[0025] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0026] It should be noted that all actions of acquiring signals, information or data in this application are carried out in compliance with the relevant data protection laws and policies of the country where they are located, and with the authorization given by the owner of the corresponding device.

[0027] In the present disclosure, unless otherwise stated, directional terms such as "axial", "circumferential", and "radial" are generally defined relative to the central axis of the balancing disc, and "inner" and "outer" refer to the inner and outer sides of the corresponding component contours. The terms "first", "second", etc. are used to distinguish different components and do not have order and importance. In addition, in the following description, when referring to the drawings, unless otherwise explained, the same reference numerals in different drawings represent the same or similar elements.

[0028] like Figures 1 to 5As shown, the present disclosure exemplarily provides a motor rotor, which includes a rotor core 1. The rotor core 1 is usually formed by a plurality of stacked silicon steel punchings. Specifically, the rotor core 1 is provided with a shaft mounting hole 11 suitable for mounting the shaft 2, and the inner wall surface of the shaft mounting hole 11 is provided with a plurality of first oil grooves 12 extending in the axial direction, and the plurality of first oil grooves 12 are arranged at intervals in the circumferential direction. The rotor core 1 is also provided with a plurality of first oil passages 13 extending in the axial direction around the shaft mounting hole 11.

[0029] In some possible application scenarios, the motor rotor provided by the present disclosure can be combined with the rotating shaft 2 and the balancing disk 3 to form a combination as shown in FIG. Figure 2 and Figure 3 In the rotor assembly shown, specifically, the rotor core 1 and the balancing plate 3 can be sleeved on the rotating shaft 2 and coaxially rotate with the rotating shaft 2. Usually, the outer peripheral wall of the rotating shaft 2 is arranged in close contact with the inner wall surface of the rotating shaft mounting hole 11, and since the present disclosure provides a plurality of first oil grooves 12 on the inner wall surface of the rotating shaft mounting hole 11, when the rotor core 1 is sleeved on the rotating shaft 2, a second oil passage 16 can be formed between the outer peripheral wall of the rotating shaft 2 and the first oil groove 12. The second oil passage 16 here is different from the first oil passage 13 provided around the rotating shaft mounting hole 11 on the rotor core 1, and the second oil passage 16 is configured to communicate with the first oil passage 13.

[0030] The rotating shaft 2 can be constructed as a hollow rotating shaft and a plurality of oil injection holes 21 are arranged on the peripheral wall. The cooling medium, such as cooling oil, enters the interior of the rotating shaft 2 through the oil inlet hole arranged at the end of the rotating shaft 2. When the rotating shaft 2 rotates, the cooling oil can be radially thrown outward from the oil injection hole 21 to the second oil passage 16 formed between the outer peripheral wall of the rotating shaft 2 and the first oil groove 12, so as to cool the interior of the rotor core 1. The second oil passage 16 is connected to the first oil passage 13, and the cooling oil in the second oil passage 16 can enter the first oil passage 13, continue to cool the interior of the rotor core 1, and finally be thrown out from the oil outlet hole 33 arranged on the balancing plate 3.

[0031] That is, two layers of cooling oil channels are formed inside the motor rotor, which is mainly different from the related art that uses cooling on the outside of the motor rotor or only forms one layer of cooling oil channels inside the motor rotor. The present application uses the first oil groove 12 set on the inner wall of the shaft mounting hole 11 and the outer peripheral wall of the shaft 2 to form the second oil channel 16, thereby adding a layer of cooling oil channels, that is, including at least two layers of cooling oil channels, the first oil channel 13 and the second oil channel 16. The two-layer oil channel design disclosed in the present invention prolongs the flow path and effective cooling time of the cooling oil inside the rotor core 1, and can cool more parts of the rotor core 1, which is conducive to improving the heat exchange efficiency of the rotor core 1, thereby improving the heat dissipation capacity of the motor rotor and ensuring the reliability of the motor operation. It should be noted that the number of layers of oil channels referred to here is different from the number of oil channels. Specifically, the rotor core 1 is provided with a plurality of first oil channels 13 around the shaft mounting hole 11, and the geometric centers of at least some of the first oil channels 13 are located on the same circle. The first oil channels 13 of this part are called the same layer of cooling oil channels.

[0032] The technical solution provided by the embodiment of the present disclosure may include the following beneficial effects: the motor rotor provided by the present disclosure is provided with a plurality of first oil grooves 12 extending in the axial direction on the inner wall surface of the shaft mounting hole 11, and the plurality of first oil grooves 12 are arranged at intervals in the circumferential direction, and a plurality of first oil passages extending in the axial direction are also arranged around the shaft mounting hole. After the motor rotor provided by the present disclosure is installed on the shaft 2, a second oil passage 16 can be formed between the outer peripheral wall of the shaft 2 and the first oil groove 12, and the second oil passage 16 is connected to the first oil passage 13, so that the cooling oil entering the motor rotor flows through the second oil passage 16 and the first oil passage 13 in sequence, that is, two layers of cooling oil passages are formed inside the motor rotor. The design of the two layers of cooling oil passages prolongs the flow path and effective cooling time of the cooling oil inside the rotor core 1, which is beneficial to improving the heat dissipation capacity of the motor rotor and ensuring the reliability of the motor operation.

[0033] Other embodiments of the motor rotor provided by the present disclosure are introduced below.

[0034] like Figure 1As shown, the rotor core 1 is provided with a plurality of weight-removing holes 131 and magnetic steel holes 132 for installing magnetic steel 15 around the rotating shaft mounting hole 11, and the weight-removing holes 131 and / or magnetic steel holes 132 are used as the first oil passages 13. Specifically, the plurality of first oil passages 13 provided on the rotor core 1 can be formed by utilizing the existing channels or mounting groove structures of the rotor core 1. Among them, according to actual needs, the weight-removing holes 131 can be utilized as the first oil passages 13, or the magnetic steel holes 132 can be utilized as the first oil passages 13, or the weight-removing holes 131 and the magnetic steel holes 132 can be utilized as the first oil passages 13 at the same time. This method of making full use of the existing structure of the rotor core 1 as the first oil passages 13 is conducive to saving design costs, without the need to redesign the oil passage position, and without the need to increase the volume of the rotor core 1 in order to add additional oil passages. Usually, after the magnetic steel holes 132 are installed, demagnetization gaps are left on both sides thereof, and the demagnetization gaps can be used as the first oil passages 13. It should be understood that the additional hole structure provided on the basis of the existing deweighting hole 131 and the magnetic steel hole 15 is still a possible implementation method of the first oil channel 13 disclosed in the present invention, which will not be described in detail here.

[0035] The plurality of first oil grooves 12 can be arranged at equal intervals along the circumferential direction. This arrangement of the first oil grooves 12 at equal intervals along the circumferential direction allows the cooling oil to be evenly distributed in the rotor core 1, which is conducive to achieving uniform heat dissipation of the motor rotor. Figure 1 As shown, six deweighting holes 131 are arranged at equal intervals around the shaft mounting hole 11, which is beneficial to evenly balancing the weight of the rotor core 1. The first oil channel 13 is also provided with six deweighting holes 131 at positions corresponding to the deweighting holes 131. The cooling oil in the second oil channel 16 can flow into the corresponding deweighting holes 131.

[0036] In order to facilitate the installation of the motor rotor, the inner wall surface of the shaft mounting hole 11 is also provided with a plurality of stoppers 14 at intervals along the circumferential direction. The stoppers 14 are adapted to cooperate with the shaft 2 so that the shaft 2 and the rotor core 1 rotate coaxially. The plurality of stoppers 14 are staggered with the first oil groove 12 in the circumferential direction. Figure 1 In the embodiment, the limiting portion 14 is configured as a convex key protruding toward the inside of the shaft mounting hole 11. Correspondingly, a keyway that cooperates with the convex key is provided on the outer peripheral wall of the shaft 2. The convex key cooperates with the keyway to achieve circumferential limiting of the rotor core 1, so that the rotor core 1 can be driven to rotate coaxially when the shaft 2 rotates. In addition, in order to enable the balancing disk 3 to rotate coaxially with the shaft 2, the balancing disk 3 can also be provided with a limiting portion similar to the convex key.

[0037] According to a second aspect of an embodiment of the present disclosure, a rotor assembly is provided, such as Figures 2 to 4As shown, the rotor assembly includes a rotating shaft 2, a balancing disc 3 and a motor rotor respectively mounted on the rotating shaft 2, and the motor rotor is any one of the motor rotors described above. The rotating shaft 2 is a hollow rotating shaft and has a plurality of oil injection holes 21 arranged on the peripheral wall, and the balancing disc 3 is arranged at both ends of the motor rotor along the axial direction and has an oil outlet hole 33. Among them: a second oil passage 16 is formed between the outer peripheral wall of the rotating shaft 2 and the first oil groove 12, the oil injection hole 21 is connected to the second oil passage 16, the second oil passage 16 is connected to the first oil passage 13, and the first oil passage 13 is connected to the oil outlet hole 33.

[0038] Under the design concept of the two-layer cooling oil channel, the flow path of the cooling oil is: the cooling oil enters the inside of the hollow shaft 2 from the oil inlet at one end, and when the shaft 2 rotates, the cooling oil can be thrown out from the oil injection hole 21 to the second oil channel 16 formed between the outer peripheral wall of the shaft 2 and the first oil groove 12, that is, enter the first layer of cooling oil channel, and as the motor rotor rotates and the cooling oil is continuously introduced, the cooling oil in the second oil channel 16 enters the first oil channel 13, that is, enters the second layer of cooling oil channel, and finally throws out the rotor assembly from the oil outlet 33. This design of two layers of cooling oil channels prolongs the flow path and effective cooling time of the cooling oil inside the rotor core 1, which is beneficial to improving the heat dissipation capacity of the motor rotor and ensuring the reliability of the motor operation.

[0039] The oil injection hole 21 can be set at the middle position of the rotating shaft 2 in the axial direction. In this way, the cooling oil thrown out from the oil injection hole 21 to the second oil channel 16 can flow symmetrically to both ends of the rotor assembly. This method of making the cooling oil flow symmetrically to both ends is less affected by the cooling oil flow rate and the motor rotor speed than the position where the oil injection hole 21 is set at the end of the rotating shaft 2, so that the cooling oil can be distributed more evenly.

[0040] like Figure 4 As described above, the balancing disk 3 may be provided with a second oil groove 31 and a third oil groove 32, wherein the second oil groove 31 is connected to the second oil channel 16, and the third oil groove 32 is connected to the second oil groove 31 and the first oil channel 13, respectively. There are a plurality of oil outlet holes 33, and the plurality of oil outlet holes 33 are arranged at intervals around the second oil groove 31 and staggered with the third oil groove 32. Among them, the two balancing disks 3 arranged at both ends of the motor rotor are configured so that the third oil groove 32 of one of them corresponds to the position of the oil outlet hole 33 of the other one, so as to achieve the effect of a tortuous flow of the cooling oil inside the motor rotor, for example, flowing in an S-shaped path, which is beneficial to improving the heat exchange efficiency. Optionally, the two balancing disks 3 at both ends adopt the same structure, and the number of the third oil grooves 32 and the oil outlet holes 33 on each balancing disk 3 is equal and is half of the first oil channel 13. Also refer to Figure 1 and Figure 4 Taking the deweighting hole 131 as the first oil passage 13 as an example, the number of the third oil grooves 32 and the number of the oil outlet holes 33 are both 3, and correspondingly, the number of the first oil passages 13 is 6.

[0041] In some embodiments, Figure 4 As shown, the second oil groove 31 is constructed in an annular shape, and a plurality of third oil grooves 32 are arranged at intervals along the circumference of the second oil groove 31, and the plurality of third oil grooves 32 all extend radially outward from the second oil groove 31. The annular second oil groove 31 has the function of buffering and collecting cooling oil, and evenly distributes the cooling oil to the third oil groove 32. The third oil groove 32 can be figuratively regarded as a plurality of branches drawn from the second oil groove 31, which are used to introduce the distributed cooling oil into the first oil channel 13.

[0042] Combine the following Figure 5 The path and effect of the above-mentioned zigzag flow of cooling oil will be described in detail.

[0043] The cooling oil enters the interior of the hollow shaft 2 from the oil inlet hole on the right side of the figure. When the shaft 2 rotates, the cooling oil can be radially thrown out from the oil injection hole 21 to the second oil channel 16 formed between the outer wall of the shaft 2 and the first oil groove 12, that is, the cooling oil enters the first layer of cooling oil channel. Since the oil injection hole 21 is opened in the middle position of the shaft 2 in the axial direction, the cooling oil entered into the second oil channel 16 flows symmetrically to the left and right ends respectively.

[0044] As the motor rotor rotates and the cooling oil is continuously introduced, taking the flow of cooling oil in the upper part of the rotating shaft 2 as an example, the cooling oil in the second oil channel 16 first flows to the left to between the end face of the rotating shaft 2 and the balancing plate 3, and then enters the first oil channel 13 through the second oil groove 31 and the third oil groove 32 in sequence, that is, the cooling oil enters the second layer of cooling oil channel. Among them, at the left end of the rotor assembly, the oil outlet 33 is closed due to the offset position with the first oil channel 13, and the cooling oil cannot be directly thrown out of the rotor assembly. At this time, the oil outlet 33 of the right end balancing plate 3 is opened because the position corresponds to the first oil channel 13, and the cooling oil flows to the right to the oil outlet 33, and then throws out the rotor assembly, thereby realizing a tortuous flow path similar to an S shape.

[0045] In other flow paths, such as the cooling oil flow path of the lower half of the rotating shaft 2, the cooling oil first flows to the right in the second oil channel 16, then enters the first oil channel 13 through the second oil groove 31 and the third oil groove 32 in sequence, and then flows to the left to the oil outlet 33 of the left end balancing plate 3 and is thrown out. On this path, the oil outlet 33 on the right end balancing plate 3 is staggered with the first oil channel 13, and the oil outlet 33 on the left end balancing plate 3 is open.

[0046] Despite Figure 5What is shown is the flow path of the upper part of the shaft 2 first to the left and then to the right, and the flow path of the lower part of the shaft 2 first to the right and then to the left. However, it should be understood that the upper part of the shaft 2 also has a flow path first to the right and then to the left, and the lower part of the shaft 2 also has a flow path first to the left and then to the right. For the sake of clarity, not all of them are shown in the figure.

[0047] According to the third aspect of the embodiment of the present disclosure, there is provided a motor, comprising the above-mentioned rotor assembly and having all its beneficial effects, which will not be repeated here. The motor can be either a generator motor or a drive motor, or a motor having both generator and drive functions.

[0048] According to a fourth aspect of an embodiment of the present disclosure, a vehicle is provided, comprising the above-mentioned motor.

[0049] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the present disclosure. This application is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary technical means in the art that are not disclosed in the present disclosure. The specification and examples are to be considered as exemplary only, and the true scope and spirit of the present disclosure are indicated by the following claims.

[0050] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A motor rotor, characterized in that: It includes a rotor core, which is provided with a shaft mounting hole. The inner wall surface of the shaft mounting hole is provided with a plurality of first oil grooves extending along the axial direction. The plurality of first oil grooves are arranged at intervals along the circumferential direction. The rotor core is also provided with a plurality of first oil channels extending along the axial direction around the shaft mounting hole.

2. The motor rotor according to claim 1, characterized in that: The rotor core is provided with a plurality of weight-removing holes and magnetic steel holes around the rotating shaft mounting hole, and the weight-removing holes and / or the magnetic steel holes are used as the first oil passages.

3. The motor rotor according to claim 1, characterized in that: The plurality of first oil grooves are arranged at equal intervals along the circumferential direction.

4. The motor rotor according to claim 1, characterized in that: The inner wall surface of the shaft mounting hole is also provided with a plurality of limit portions at intervals along the circumferential direction, which are suitable for cooperating with the shaft so that the shaft and the rotor core rotate coaxially, and the plurality of limit portions are staggered with the first oil groove in the circumferential direction.

5. A rotor assembly, characterized in that: It includes a rotating shaft and a balancing disk and a motor rotor respectively mounted on the rotating shaft, wherein the motor rotor is the motor rotor according to any one of claims 1 to 4; the rotating shaft is a hollow rotating shaft and a plurality of oil injection holes are arranged on the peripheral wall; the balancing disk is provided with an oil outlet hole, wherein: a second oil passage is formed between the outer peripheral wall of the rotating shaft and the first oil groove, the oil injection hole is connected to the second oil passage, the second oil passage is connected to the first oil passage, and the first oil passage is connected to the oil outlet hole.

6. The rotor assembly according to claim 5, characterized in that The oil injection hole is arranged at the middle position of the rotating shaft along the axial direction.

7. The rotor assembly according to claim 6, characterized in that The balancing plate is provided with a second oil groove and a third oil groove, wherein the second oil groove is communicated with the second oil channel, and the third oil groove is communicated with the second oil groove and the first oil channel respectively, and there are multiple oil outlet holes, and the multiple oil outlet holes are arranged around the second oil groove at intervals and staggered with the third oil groove, wherein the two balancing plates arranged at both ends of the motor rotor are configured so that the third oil groove of one of them corresponds to the position of the oil outlet hole of the other one.

8. The rotor assembly according to claim 7, characterized in that The two balancing plates at both ends have the same structure, and the number of the third oil grooves and the oil outlet holes on each balancing plate is equal and is half of the first oil passage.

9. The rotor assembly according to claim 7, characterized in that: The second oil groove is configured in an annular shape, and a plurality of the third oil grooves are arranged at intervals along the circumferential direction of the second oil groove, and the plurality of third oil grooves all extend radially outward from the second oil groove.

10. A motor, characterized in that: A rotor assembly comprising any one of claims 5-9.

11. A vehicle, characterized in that: The motor comprising the motor described in claim 10.

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