CN114421678A

CN114421678A - Rotor assembly, motor and vehicle

Info

Publication number: CN114421678A
Application number: CN202210044473.6A
Authority: CN
Inventors: 倪良军; 林霄喆; 谭艳军; 方亮; 张胜川; 韩韬; 于海生; 王瑞平; 肖逸阁
Original assignee: Zhejiang Geely Holding Group Co Ltd; Ningbo Geely Royal Engine Components Co Ltd; Aurobay Technology Co Ltd
Current assignee: Wuxi Xingqu Power Technology Co ltd; Wuxi Xingqu Technology Co ltd
Priority date: 2022-01-14
Filing date: 2022-01-14
Publication date: 2022-04-29

Abstract

A rotor assembly, an electric machine and a vehicle are provided herein. The rotor assembly comprises a rotor core and a rotor shaft, and the rotor core is sleeved on the periphery of the rotor shaft; the rotor shaft includes: the shaft body and the oil passing groove; the axis body includes oil feed section and cooperation section, the oil feed section is equipped with along the oil feed passageway of axial extension, the rotor core cover is located cooperation section periphery side, the cooperation section has the oil feed inner chamber, the oil feed passageway with oil feed inner chamber intercommunication, cross the oil groove set up in on the lateral wall of cooperation section, cross the oil groove with oil feed inner chamber intercommunication, cross the oil groove and run through the lateral wall of cooperation section, at least part the internal surface of rotor core exposes in cross the oil groove, make the process the cooling lubricating oil of rotor shaft can pass through cross the oil groove water conservancy diversion and arrive the internal surface of rotor core to show the cooling and lubrication efficiency who improves the rotor assembly.

Description

Rotor assembly, motor and vehicle

Technical Field

This paper relates to but not the vehicle technical field, especially relates to a rotor assembly, motor and vehicle.

Background

The motor is one of the core parts of the power output of the electric automobile, and is required to have high power density, high torque density, high system efficiency, light weight, low cost, better mass production manufacturability and the like so as to meet the requirements of users on high performance, low cost and the like of electric and hybrid automobiles.

Cooling lubrication is very important for electric machines, especially for high performance electric machines. The high-performance motor generates more heat and needs to reduce the working temperature to a range which can be borne by motor parts through cooling and lubricating. Taking an ac asynchronous motor as an example, the main heating elements in the motor are a stator winding, a stator core, a rotor core and a permanent magnet. At present, in the cooling and lubricating technology of the motor for the automobile, three cooling modes of air cooling, water cooling and oil cooling are mainly adopted, wherein the oil cooling is the main cooling and lubricating mode of the high-performance motor. At present, in the industry, a plurality of cooling and lubricating schemes for the motor stator assembly are adopted, the cooling and lubricating scheme is relatively mature, the cooling and lubricating scheme for the motor rotor assembly is less, and particularly, the cooling and lubricating scheme is efficient.

At present, the mainstream scheme of cooling and lubricating a motor rotor assembly is that cooling lubricating oil is guided into a hollow rotor shaft through an oil pump, enters oil holes in pressing plates at two ends through an oil hole of the hollow rotor shaft and then flows into an oil hole of a rotor core so as to cool and lubricate the rotor core, and then splashes to a winding at the end part of a stator through the oil hole of the pressing plate under the action of centrifugal force so as to cool and lubricate the winding. The cooling and lubricating scheme mainly has the problem that the cooling and lubricating efficiency is low and the requirement of a high-performance motor cannot be met.

The above description is included in the technical recognition scope of the inventors, and does not necessarily constitute the prior art.

Disclosure of Invention

The application aims to provide a rotor assembly, a motor and a vehicle so as to remarkably improve the cooling and lubricating efficiency of the rotor assembly.

The technical scheme of the embodiment of the application is as follows:

a rotor assembly comprises a rotor core and a rotor shaft, wherein the rotor core is sleeved on the periphery of the rotor shaft; the rotor shaft includes: the shaft body and the oil passing groove; the axis body includes oil feed section and cooperation section, the oil feed section is equipped with along the oil feed passageway of axial extension, the rotor core cover is located cooperation section periphery side, the cooperation section has the oil feed inner chamber, the oil feed passageway with oil feed inner chamber intercommunication, cross the oil groove set up in on the lateral wall of cooperation section, cross the oil groove with oil feed inner chamber intercommunication, cross the oil groove and run through the lateral wall of cooperation section, at least part the internal surface of rotor core exposes in cross the oil groove, make the process the cooling lubricating oil of rotor shaft can pass through cross the oil groove water conservancy diversion and arrive the internal surface of rotor core.

Through arranging the oil groove of crossing that sets up with rotor core relatively on the cooperation section at rotor shaft for rotor core at least partial internal surface exposes and crosses the oil groove, with the direct water conservancy diversion of the cooling lubricating oil that will flow into from oil feed passageway to rotor core's internal surface on, optimizes the circulation route of cooling lubricating oil on the whole, effectively improves rotor assembly's cooling and lubrication efficiency.

In some exemplary embodiments, a plurality of the oil passing grooves are uniformly arranged at equal intervals along the circumferential direction of the shaft body, the oil passing grooves penetrate through the matching section along the radial direction of the matching section, and the oil passing grooves extend along the axial direction of the shaft body.

It is a plurality of cross the oil groove edge the circumference of axis body is equidistant evenly to be set up, and makes the oil groove along the radial cooperation section that runs through of cooperation section for the cooperation section of axis body presents the design condition of fretwork, reduces the weight of rotor shaft on the one hand, and on the other hand improves the circulation of crossing oil, promotes cooling and lubrication's efficiency.

In some exemplary embodiments, the diameter of the mating section is greater than the diameter of the oil inlet section, the oil inlet section and the mating section form a stepped structure, and the wall thickness of the stepped structure is greater than the wall thickness of the oil inlet section.

The rotor shaft is designed in a segmented and differentiated mode, the overall structure layout is optimized, the weight of the rotor shaft can be reduced, the diameter requirement of the motor on the matching area of the rotor shaft and the rotor core can be met, and the transmission performance is met. Moreover, the oil inlet section and the matching section are designed to be step-shaped, so that the manufacturing process is effectively simplified, and the manufacturing cost is reduced.

In some exemplary embodiments, the shaft body is a unitary structure, the shaft body is a hollow shaft, and the oil passing groove is a hollow structure formed in the shaft body.

Through the optimal design of the overall structure of the oil passing groove and the shaft body, the shaft body can be obtained in an integrated forming mode, the complexity of a manufacturing process is reduced, and the manufacturing precision of the rotor shaft can also be improved.

In some exemplary embodiments, the inner wall of the oil inlet passage is provided with a spiral groove, and the spiral groove rotates in the same direction as the rotation direction of the rotor shaft.

The spiral groove is formed in the inner wall of the oil inlet channel, so that a certain flow guide effect is achieved on cooling lubricating oil, the speed loss of the cooling lubricating oil in the flowing process is reduced, and the cooling lubricating cost is reduced.

In some exemplary embodiments, the rotor shaft further comprises an oil outlet section, the oil outlet section is provided with an oil outlet channel, the oil outlet channel and the oil inlet channel are coaxially arranged, and the oil outlet channel is communicated with the oil inlet channel through the oil inlet inner cavity.

Through setting up the oil outlet channel that is linked together with the oil feed passageway to carry out cooling lubrication to other parts that set up on the rotor shaft, improve cooling lubrication efficiency.

In some exemplary embodiments, more than one first flow guiding grooves extending in the axial direction of the rotor core are formed in the inner wall of the rotor core, the first flow guiding grooves penetrate through two end faces of the rotor core, openings of the first flow guiding grooves face the inner cavity of the rotor core, an overflowing channel is formed at the first flow guiding grooves by the rotor core and the rotor shaft, and the overflowing channel is communicated with the oil inlet inner cavity.

After cooling oil comes out from the rotor shaft, through setting up the first water conservancy diversion recess on the rotor core inner wall to flow to rotor core's both ends, increase cooling oil and rotor core's area of contact on the one hand, on the other hand can conveniently cool off and lubricate stator assembly.

In some exemplary embodiments, the rotor assembly further comprises two platens; at least part of the rotor iron core is tightly pressed between the two pressing plates, and the pressing plates are abutted against and fixedly connected with the step structure of the rotor shaft;

the pressing plate is provided with more than one flow guide hole, and the flow guide holes are communicated with the first flow guide grooves.

Through setting up the clamp plate and setting up the water conservancy diversion hole on the clamp plate for the cooling lubricating oil after first water conservancy diversion recess flows according to the route of design, with the energy loss of effectively reducing the flow in-process. The cooling lubricating oil splashes out from the two ends of the rotor assembly after flowing through the diversion holes, and the stator winding of the stator assembly can be cooled and lubricated.

An electric machine comprising a stator assembly and a rotor assembly; the rotor assembly is the rotor assembly of any one of the above embodiments, the stator assembly is located at the periphery of the rotor core, and the rotor assembly further comprises two pressing plates; the two pressing plates are respectively arranged at two ends of the oil passing groove; the pressing plate is provided with more than one flow guide hole, and the flow guide holes are communicated with the first flow guide groove;

wherein the diversion holes are arranged to divert cooling lubricant passing through the rotor assembly to a space in which a stator winding of the stator assembly is located; the diversion holes are arc-shaped holes along the circumferential direction of the rotor shaft.

Set up the water conservancy diversion hole into the arc hole that extends along rotor shaft circumference, suit with the circular motion of rotor assembly for cooling lubricating oil splashes out with great circulation passageway through curved water conservancy diversion hole under the effect of circumference inertia force, carries out the effective cooling of large tracts of land and lubrication to the stator winding of stator assembly with the realization.

A vehicle comprises the motor of the embodiment.

Other aspects will be apparent upon reading and understanding the attached drawings and detailed description.

Drawings

The accompanying drawings are included to provide a further understanding of the embodiments herein and are incorporated in and constitute a part of this specification, illustrate embodiments herein and are not to be construed as limiting the embodiments herein.

Fig. 1 is an exploded view of a motor according to an embodiment of the present disclosure;

FIG. 2 is a first schematic cross-sectional view of a rotor shaft according to an embodiment of the present application;

FIG. 3 is a schematic cross-sectional view of a rotor shaft according to an embodiment of the present application;

fig. 4 is a schematic cross-sectional view of a motor according to an embodiment of the present application.

Reference numerals:

1-a rotor shaft, 11-a shaft body, 11 a-an oil inlet section, 11 b-a matching section, 11 c-an oil outlet section, 11 d-a step structure, 12-an oil passing groove, 13-a spiral groove and 14-a second diversion groove;

2-rotor core, 21-first diversion groove;

3-stator assembly, 31-stator winding, 32-stator core;

4-pressing plate, 41-flow guiding hole.

Detailed Description

The technical scheme is further explained by the specific implementation mode in combination with the attached drawings. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not to be construed as limitations.

In one embodiment of the present application, as shown in fig. 1-4, a rotor assembly is provided. This rotor assembly includes rotor core 2 and rotor shaft 1, and rotor core 2 cover is in the periphery of rotor shaft 1. The rotor shaft 1 includes a shaft body 11 and an oil sump 12 provided in the shaft body 11. An oil inlet channel is arranged on the shaft section of the shaft body 11, and the whole shaft body 11 can be set into a hollow shaft. The shaft body 11 may also be a partially hollow shaft section machined into a partial shaft section of a solid shaft, and a passage in the partially hollow shaft section serves as an oil inlet passage.

The oil passing groove 12 is disposed on a sidewall of the shaft body 11 and penetrates the sidewall of the shaft body 11. The oil sump 12 may be axially centered on the shaft body 11. The cross section of the oil passing groove 12 in the axial direction may be shaped as a rectangular, oblong, kidney-shaped hole, or the like. The oil passing groove 12 is communicated with an oil inlet channel arranged inside the shaft body 11. Oil passing groove 12 is provided near one end of rotor core 2 to serve as an oil outlet.

As shown in fig. 1, the shaft body 11 may be configured to include an oil inlet section 11a and a fitting section 11b, which are sequentially arranged, and diameters of the two shaft sections may be configured to be different. The oil passing groove 12 may be provided on the fitting section 11b, and the fitting section 11b is fitted with the rotor core 2. The axial dimension of the oil passing groove 12 can be designed to be slightly smaller than that of the rotor core 2, so that the cooling lubricating oil is prevented from being splashed arbitrarily to influence the cleanliness in the rotor assembly. An oil inlet passage is provided on the oil inlet section 11 a. An oil inlet inner cavity is arranged in the matching section 11b, and one end of the oil inlet inner cavity is communicated with one end of the oil inlet channel. As shown in fig. 4, the cooling lubricant enters from the other end (left end in the figure) of the oil inlet passage, flows through the oil inlet cavity, and then flows out from the oil passing groove 12, so that the cooling lubricant is guided to a part of or the whole inner surface of the rotor core 2, thereby cooling and lubricating the rotor core 2.

From the design of whole rotor shaft 1, can set up the oil-out of different forms, oil groove 12 can regard as the oil-out to use, along the rotor shaft 1 one end of extending axially, the one end that is opposite to oil feed passageway also can regard as the oil-out to use. The overall layout of the oil outlet is related to the specific structure of the motor, and the adaptability is increased. The oil passing grooves 12 which are arranged opposite to the rotor core 2 are formed in the rotor shaft 1, so that part or all of the cooling lubricating oil is directly guided to the rotor core 2, the circulation path of the cooling lubricating oil is optimized on the whole, and the cooling and lubricating efficiency of the rotor assembly is effectively improved.

In some exemplary embodiments, as shown in fig. 1, a plurality of oil passing grooves 12 may be provided at intervals along the circumference of the fitting section 11 b. The plurality of oil passing grooves 12 may be uniformly disposed at equal intervals and extend in the axial direction of the shaft body 11. The oil passing groove 12 may also penetrate the fitting section 11b in a radial direction of the fitting section 11b, i.e., from one sidewall of the fitting section 11b to the other sidewall of the opposite side in a diameter direction. In the figure, four rectangular oil passing grooves 12 are provided at equal intervals as an example to explain the technical scheme in detail. The oil grooves 12 make a partial shaft section of the shaft body 11 have a hollow design. The hollow structure can reduce the whole weight of the rotor shaft 1 on the one hand, and on the other hand, the oil passing flux of the cooling lubricating oil in unit time can be improved, so that the cooling and lubricating efficiency of the motor is effectively improved, and the high efficiency is realized.

In some exemplary embodiments, as shown in fig. 1, the diameter of the matching section 11b is greater than that of the oil inlet section 11a, that is, as a whole, the shaft body 11 may be in a stepped shaft design, a stepped structure 11d is formed between the oil inlet section 11a and the matching section 11b, a wall thickness H of the stepped structure 11d is greater than a wall thickness H of the oil inlet section 11a, and as shown in fig. 2, on one side (upper side or lower side along the central axis) of the shaft body 11, the thickness of the stepped structure 11d in the up-down direction is greater than that of the oil inlet section 11a, so as to ensure the strength of the matching shaft section between the rotor shaft 1 and the rotor core 2. The oil inlet section 11a and the matching section 11b may be provided as hollow shaft sections of equal wall thickness. The rotor shaft 1 is designed in a segmented and differentiated mode, the overall structure is optimized, the weight of the rotor shaft 1 can be reduced, and the diameter requirement of a motor on the matching area of the rotor shaft 1 and the rotor iron core 2 can be met, so that the transmission performance is met. The shaft body 11 is designed as a stepped shaft, so that the processing complexity can be reduced, and the manufacturing cost of the rotor assembly can be reduced.

In some exemplary embodiments, as shown in fig. 1, the shaft body 11 may also be configured to include an oil outlet section 11 c. The oil inlet section 11a, the matching section 11b and the oil outlet section 11c can be communicated in sequence. What set up in the section of producing oil 11c is the passageway of producing oil, and the passageway of producing oil can be with the central axis setting with the oil feed passageway. The oil outlet channel is communicated with the oil inlet channel through the oil inlet inner cavity to form another cooling lubricating oil passage, and an oil outlet can be formed in the end, which is not communicated with the matching section 11b, of the oil outlet section 11 c. The oil outlet section 11c may also be designed in a closed manner to increase the product diversity of the rotor shaft 1. The oil inlet section 11a, the matching section 11b and the oil outlet section 11c can be arranged to be of an integrally formed structure, and the central axis is designed in a collinear mode. By the design, the rotor shaft 1 can be assembled without sectional molding, the complexity of the manufacturing process of the rotor shaft 1 is reduced on the whole, and the manufacturing precision of the rotor shaft 1 can be effectively improved.

In some exemplary embodiments, as shown in fig. 2 and 3, a spiral groove 13 is provided on the inner wall of the oil inlet passage of the rotor shaft 1. The spiral groove 13 may be provided only on the inner wall of the oil feed section 11 a. A spiral groove 13 may be provided on the inner wall of the oil outlet section 11 c. The cross-sectional shape of the spiral groove 13 may be set to be semicircular, triangular, rectangular, or the like. It is also possible to provide two spiral grooves 13 or three spiral grooves 13 on the inner wall of the rotor shaft 1. The rotating direction of the spiral groove 13 is set to be the same as the rotating direction of the rotor shaft 1, so that a certain flow guiding effect is achieved on the cooling lubricating oil, and the cooling lubricating oil is pushed to flow forwards. The spiral groove 13 can reduce the speed loss of the cooling lubricating oil in the flowing process to a certain extent, so that the effect of reducing the cooling lubricating cost is achieved.

In some exemplary embodiments, as shown in fig. 1, one or more first guide grooves 21 are provided on the inner wall of the rotor core 2. The first diversion groove 21 is designed to be through along the thickness direction (axial direction) of the rotor core 2, and an opening of the first diversion groove 21 faces an inner cavity of the rotor core 2. The rotor core 2 and the rotor shaft 1 form a plurality of flow channels along the axial direction of the rotor core 2 at the first flow guide groove 21. The plurality of overflowing passages are communicated with the oil inlet inner cavity. The cross-sectional shape of the first guide groove 21 may be set to be semicircular, arc-shaped, or the like. The plurality of first guide grooves 21 are uniformly arranged in the circumferential direction of the rotor core 2 or are arranged at unequal intervals. As shown by the dashed arrow lines in fig. 4, the cooling lubricant flows out from the oil passing groove 12 of the rotor shaft 1, and a part of the cooling lubricant enters the gap between the rotor shaft 1 and the rotor core 2 and then passes through the first guide groove 21 provided on the inner wall of the rotor core 2 to flow toward the two ends of the rotor core 2. The flow path of the cooling lubricant can increase the contact area of the cooling lubricant and the rotor core 2 on the one hand, and can facilitate the subsequent cooling and lubrication of the stator assembly 3 on the other hand.

In some exemplary embodiments, as shown in fig. 1, a second guide groove 14 may be provided on an outer wall of the fitting section 11b, the second guide groove 14 extending in an axial direction of the fitting section 11 b. The cross-sectional shape of the second guide groove 14 may be set to be the same as the cross-sectional shape of the first guide groove 21. The plurality of second guide grooves 14 may be disposed at equal intervals in a circumferential direction of the fitting section 11 b. The first diversion grooves 21 and the second diversion grooves 14 can be arranged in sequence at intervals.

In some exemplary embodiments, as shown in fig. 1 and 4, the rotor assembly further includes two platens 4. The two pressing plates 4 are respectively positioned at the left and right ends of the fitting section 11 b. A part or the whole of the rotor core 2 is compressed between the two pressing plates 4. The pressure plate 4 may be in contact with and fixed, for example optionally bolted, to the stepped structure of the rotor shaft 1. After the motor is assembled in place, the stator winding 31 in the stator assembly 3 is fixed on the stator core 32 in a winding mode. Both the left and right ends of the stator winding 31 extend a length beyond the stator core 32.

One or more guiding holes 41 are provided in the pressure plate 4. Wherein, the whole or partial flow area of the diversion hole 41 is communicated with the first diversion groove 21, or communicated with the second diversion groove 14, etc. In an actual working state, as shown in fig. 4, cooling lubricant is introduced into the oil inlet channel of the rotor shaft 1 from the oil pool through an oil pipe or an oil passage by a device such as an electronic oil pump, and a centripetal force generated in the rotation process of the oil inlet channel and the rotor shaft 1 is decomposed into an axial force along the axial direction of the rotor shaft 1, and the axial force pushes the cooling lubricant to flow forward, so that the flow rate of the cooling lubricant is further increased, and the lubricating effect is improved. A part of the cooling lubricant flows to the rotor core 2 through the oil groove 12, and then flows through the guide holes 41 after passing through the first guide groove 21, so that the cooling lubricant splashes from the two ends of the rotor assembly, and the stator winding 31 is cooled and lubricated.

In some exemplary embodiments, as shown in fig. 1, the two pressing plates 4 may be configured to be identical to reduce the number of parts and the management cost of parts. In the actual assembly into a motor, the pressure plate 4 can be brought to different rotation angles for fitting onto the rotor shaft 1. The guide holes 41 of the left-hand press plate 4 can be arranged to communicate with a part of the first guide grooves 21 of the rotor core 2. The guiding holes 41 of the pressing plate 4 on the right side can be arranged to be communicated with the remaining first guiding grooves 21 on the rotor core 2. The number of the first flow guiding grooves 21 communicated with the flow guiding holes 41 positioned on the left side is the same as that of the first flow guiding grooves 21 communicated with the flow guiding holes 41 positioned on the right side, so that the uniformity of flow guiding to the two ends of the stator winding 31 is increased, and the reliability of the motor is improved.

In some exemplary embodiments, as shown in fig. 1, the pilot holes 41 may be provided as arc-shaped holes extending in the circumferential direction of the rotor shaft 1. The arc-shaped hole is matched with the circular motion of the rotor assembly, and the center of the arc-shaped hole and the central axis of the rotor shaft 1 can be arranged to be collinear, so that the cooling lubricating oil splashes out through the arc-shaped flow guide hole 41 by a larger flow passage under the action of the circumferential inertia force, and is used for guiding the cooling lubricating oil passing through the rotor assembly to the space where the stator winding 31 of the stator assembly 3 is located, as shown in fig. 4.

In another embodiment of the present application, as shown in fig. 1 and 4, a motor is further provided. The machine comprises a stator assembly 3 and a rotor assembly. The rotor assembly is configured as the rotor assembly according to any of the embodiments, so that all the advantages of the rotor assembly are achieved, and further description is omitted here.

In yet another embodiment of the present application, a vehicle is also provided. The vehicle comprises the motor according to the above embodiment. Therefore, the vehicle has all the beneficial effects of the motor, and the description is omitted.

In the description herein, the terms "upper", "lower", "one side", "the other side", "one end", "the other end", "side", "opposite", "four corners", "periphery", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing embodiments of the present application and simplifying the description, but do not indicate or imply that the structures referred to have particular orientations, are constructed and operated in particular orientations, and thus, are not to be construed as limiting the present disclosure.

In the description of the embodiments of the present application, unless otherwise explicitly stated or limited, the terms "connected," "directly connected," "indirectly connected," "fixedly connected," "mounted," and "assembled" are to be construed broadly and, for example, may be fixedly connected, detachably connected, or integrally connected; the terms "mounted," "connected," and "fixedly connected" may be directly connected or indirectly connected through intervening media, or may be connected through two elements. The specific meaning of the above terms herein can be understood in a specific context to one of ordinary skill in the art.

Although the embodiments disclosed herein are described above, the descriptions are only for the convenience of understanding the embodiments and are not intended to limit the disclosure. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure, and that the scope of the disclosure herein is to be limited only by the appended claims.

Claims

1. The utility model provides a rotor assembly, includes rotor core and rotor shaft, the rotor core cover is located the rotor shaft periphery, its characterized in that, the rotor shaft includes: the shaft body and the oil passing groove; the axis body includes oil feed section and cooperation section, the oil feed section is equipped with along the oil feed passageway of axial extension, the rotor core cover is located cooperation section periphery side, the cooperation section has the oil feed inner chamber, the oil feed passageway with oil feed inner chamber intercommunication, cross the oil groove set up in on the lateral wall of cooperation section, cross the oil groove with oil feed inner chamber intercommunication, cross the oil groove and run through the lateral wall of cooperation section, at least part the internal surface of rotor core exposes in cross the oil groove, make the process the cooling lubricating oil of rotor shaft can pass through cross the oil groove water conservancy diversion and arrive the internal surface of rotor core.

2. The rotor assembly according to claim 1, wherein a plurality of the oil passing grooves are uniformly arranged at equal intervals in a circumferential direction of the shaft body, the oil passing grooves penetrate the engagement section in a radial direction of the engagement section, and the oil passing grooves extend in an axial direction of the shaft body.

3. The rotor assembly of claim 2, wherein the diameter of the mating section is greater than the diameter of the oil inlet section, the oil inlet section and the mating section forming a stepped structure having a wall thickness greater than a wall thickness of the oil inlet section.

4. The rotor assembly of claim 3, wherein the shaft body is a unitary structure, the shaft body is a hollow shaft, and the oil-passing groove is a hollowed-out structure formed in the shaft body.

5. A rotor assembly according to any one of claims 1 to 4, wherein the inner wall of the oil inlet passage is provided with a helical groove, the direction of rotation of the helical groove being the same as the direction of rotation of the rotor shaft.

6. The rotor assembly of claim 5, wherein the rotor shaft further includes an oil outlet section, the oil outlet section having an oil outlet passage, the oil outlet passage being disposed coaxially with the oil inlet passage, the oil outlet passage being in communication with the oil inlet passage through the oil inlet inner cavity.

7. The rotor assembly according to claim 5, wherein the inner wall of the rotor core is provided with at least one first flow guiding groove extending along the axial direction of the rotor core, the first flow guiding groove penetrates through two end faces of the rotor core, an opening of the first flow guiding groove faces the inner cavity of the rotor core, the rotor core and the rotor shaft form an overflowing channel at the first flow guiding groove, and the overflowing channel is communicated with the oil inlet inner cavity.

8. The rotor assembly of claim 7, further comprising two platens; at least part of the rotor iron core is tightly pressed between the two pressing plates, and the pressing plates are abutted against and fixedly connected with the step structure of the rotor shaft;

9. An electric machine comprising a stator assembly and a rotor assembly; the rotor assembly is the rotor assembly of any one of claims 1-7, the stator assembly is located on the periphery of the rotor core, and the rotor assembly further comprises two pressing plates; the two pressing plates are respectively arranged at two ends of the oil passing groove; the pressing plate is provided with more than one flow guide hole, and the flow guide holes are communicated with the first flow guide groove;

10. A vehicle comprising the electric machine of claim 9.