CN221227232U - Rotor punching sheet, motor and vehicle - Google Patents

Abstract

The application discloses a rotor punching sheet, a motor and a vehicle, and aims to solve the technical problems of large overall loss and poor heat dissipation effect of the existing asynchronous motor. According to the application, the weight reducing holes are arranged on the rotor punching sheet, so that the weight of the rotor is optimized, and the power density of the motor is effectively improved. The inner wall of the lightening hole is of a sawtooth structure, so that the convection heat exchange area of the rotor and air is increased, the rotor dissipates heat more fully, and the heat dissipation effect of the motor is improved.

Description

Rotor punching sheet, motor and vehicle

Technical Field

The application belongs to the technical field of rotors, and particularly relates to a rotor punching sheet, a motor and a vehicle.

Background

The aluminum cage rotor asynchronous motor has the advantages of simple structure, low cost, reliable operation and the like, and in recent years, along with the further application of the electric automobile auxiliary motor technology, the asynchronous motor also receives wide attention. The further increase of the rotation speed of the motor for the vehicle has higher and higher requirements on the performance of the motor.

The existing asynchronous motor has solid rotor and large overall loss, and in the actual operation process, the rotor is generally the place with the largest temperature rise change of the asynchronous motor, and the heat dissipation effect is poor.

Disclosure of Invention

The application provides a rotor punching sheet, a motor and a vehicle, which are used for solving the technical problems of large overall loss and poor heat dissipation effect of the existing asynchronous motor.

In a first aspect of the present application, there is provided a rotor punching sheet, the rotor punching sheet is provided with a lightening hole and a mounting hole for a rotor shaft to extend into, the lightening hole is provided with a plurality of lightening holes, the lightening holes are wound around the mounting hole along the circumferential direction of the mounting hole, the lightening holes are arranged at intervals, and the wall of the lightening hole is provided with a recess and/or a protrusion.

In some embodiments, the lightening holes are provided with the recesses and/or protrusions along both the first and second side walls of the rotor sheet in the radial direction.

In some embodiments, the first and second sidewalls are each provided with a protrusion, the protrusion being provided with a groove; the distance between the two grooves arranged along the radial direction of the rotor punching sheet is smaller than the distance between the first side wall and the second side wall.

In some embodiments, the lightening hole is a rectangular hole, and the first side wall and the second side wall are both long sides of the rectangular hole; the protrusions are provided with a plurality of grooves which are distributed at intervals; the grooves are triangular grooves.

In some embodiments, the rotor punching sheet is provided with a plurality of guide holes for the squirrel cage guide bars to extend into, the guide holes are wound at intervals along the circumferential direction of the mounting hole, and the guide holes are positioned on the radial outer side of the lightening hole along the rotor punching sheet.

In a second aspect of the present application, there is provided an electric machine comprising:

The rotor assembly comprises a rotating shaft and a plurality of rotor punching sheets of the first aspect which are stacked in sequence, and the lightening holes of the rotor punching sheets are communicated in one-to-one correspondence; the rotating shaft is arranged in the mounting hole;

and the stator assembly is sleeved outside the rotor punching sheets.

In some embodiments, the rotor assembly further comprises a squirrel cage having two end rings located at axial ends of the plurality of rotor blades, the end rings being located outside the lightening holes along an axial projection of the shaft.

In some embodiments, the rotating shaft is provided with a shaft shoulder, the rotor assembly further comprises a limiting ring connected to the rotating shaft, the rotor punching sheets are located between the shaft shoulder and the limiting ring, and the weight reducing holes are exposed out of the shaft shoulder and the limiting ring.

In some embodiments, the motor further comprises a housing provided with a receiving cavity, the rotor assembly and the stator assembly are both positioned in the receiving cavity, the housing is provided with a cooling flow passage for cooling liquid to circulate, and an inlet and an outlet communicated with the cooling flow passage, and the cooling flow passage is arranged around the rotating shaft and distributed in a serpentine manner along the circumferential direction of the housing.

In a second aspect of the application, there is provided a vehicle comprising the electric machine of the second aspect.

According to the rotor punching sheet provided by the embodiment of the application, the rotor punching sheet is provided with the lightening holes and the mounting holes for the rotor rotating shaft to extend in, the lightening holes are multiple, the lightening holes are wound outside the mounting holes along the circumferential direction of the mounting holes, the lightening holes are arranged at intervals, and the hole walls of the lightening holes are provided with the concave and/or convex parts.

The rotor punching sheet is provided with a mounting hole, the rotor rotating shaft can be mounted in the mounting hole, and the rotor punching sheet rotates to drive the rotor rotating shaft to rotate so as to transmit power to the rotor rotating shaft, and then the rotor rotating shaft is transmitted to the wheel and other structures.

The rotor punching sheet is provided with the weight reducing holes, so that the weight of the rotor assembly can be reduced, the motor is light, and the power density of the motor is improved. The lightening holes are positioned outside the mounting holes, namely, the lightening holes are distributed on the outer sides of the mounting holes along the radial direction of the rotor punching sheet, and the rotor rotating shaft cannot be interfered to be mounted in the mounting holes of the rotor punching sheet. The lightening holes are arranged at intervals, so that the integral strength of the rotor punching sheet can be ensured; the wall of the lightening hole is provided with the concave and/or convex, so that the part of the lightening hole is provided with a saw tooth structure, the heat dissipation area of the rotor and the air in the lightening hole is increased, the heat transfer between the rotor and the air is promoted, the air in the lightening hole flows when the rotor punching sheet works, the heat of the rotor is taken away, the heat dissipation of the rotor of the motor is optimized, and the further temperature rise of the rotor punching sheet and the rotor rotating shaft is restrained; meanwhile, the sawtooth structure also improves the strength of the rotor punching to a certain extent.

Therefore, the application arranges the lightening holes on the rotor punching sheet, optimizes the weight of the rotor and effectively improves the power density of the motor. The inner wall of the lightening hole is of a sawtooth structure, so that the convection heat exchange area of the rotor and air is increased, the rotor dissipates heat more fully, and the heat dissipation effect of the motor is improved.

Drawings

Fig. 1 shows a schematic structural view of a rotor punching sheet in one or more embodiments of the application.

FIG. 2 illustrates a schematic structural diagram of a rotor assembly in one or more embodiments of the application.

FIG. 3 illustrates a cross-sectional view of the rotor assembly of FIG. 2.

Reference numerals illustrate:

100-rotating shafts, 110-shaft shoulders, 200-limiting rings, 300-compression rings, 400-iron cores, 410-rotor punching sheets, 411-weight reducing holes, 412-first side walls, 413-second side walls, 414-grooves, 415-mounting holes, 416-rotation stopping protrusions, 417-guide holes, 420-weight reducing channels and 500-end rings.

Detailed Description

In order to make the present application more clearly understood by those skilled in the art, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

According to the embodiment of the first aspect of the application, the rotor punching sheet is provided, and the weight reducing holes of the rotor punching sheet have the weight reducing effect, so that the heat radiating area can be increased, and the heat radiating efficiency can be improved.

Referring to fig. 1, in the rotor punching sheet 410 provided by the embodiment of the application, a lightening hole 411 and a mounting hole 415 for the rotor shaft 100 to extend into are provided, the lightening hole 411 is provided with a plurality of lightening holes 411, the lightening holes 411 are wound around the mounting hole 415 along the circumference of the mounting hole 415, the lightening holes 411 are arranged at intervals, and the wall of the lightening hole 411 is provided with a recess and/or a protrusion.

The rotor punching sheet 410 is provided with a mounting hole 415, the rotor rotating shaft 100 can be mounted in the mounting hole 415, and the rotor punching sheet 410 rotates to drive the rotor rotating shaft 100 to rotate, so that power is transmitted to the rotor rotating shaft 100, and then the rotor rotating shaft 100 is transmitted to the wheel and other structures.

The rotor punching sheet 410 is provided with the weight reducing holes 411, so that the weight of the rotor assembly can be reduced, the motor is light, and the power density of the motor is improved. The weight-reducing holes 411 are provided in plurality, for example, the weight-reducing holes 411 are provided in three, five, ten, etc., and the number of the weight-reducing holes 411 may be determined according to the size of the rotor sheet 410. The lightening holes 411 are located outside the mounting holes 415, that is, the lightening holes 411 are distributed on the outer side of the mounting holes 415 along the radial direction of the rotor punching sheet 410, so that the rotor shaft 100 does not interfere with the mounting holes 415 of the rotor punching sheet 410. The weight reducing holes 411 are arranged at intervals, so that the overall strength of the rotor punching sheet 410 can be ensured, the hole wall of the weight reducing hole 411 is provided with a recess and/or a protrusion, namely, the hole wall of the weight reducing hole 411 is provided with a recess, or the hole wall of the weight reducing hole 411 is provided with a protrusion, or the hole wall of the weight reducing hole 411 is provided with a recess and a protrusion; the hole wall of the lightening hole 411 is provided with a recess and/or a protrusion, so that the part of the lightening hole 411 is provided with saw teeth, the heat dissipation area of the rotor and the air in the lightening hole 411 is increased, the heat transfer between the rotor and the air is promoted, when the rotor punching sheet 410 works, the air in the lightening hole 411 flows to take away the heat of the rotor, the heat dissipation of the rotor of the motor is optimized, and the further temperature rise of the rotor punching sheet 410 and the rotor rotating shaft 100 is restrained.

In some embodiments, the plurality of depressions are provided in a plurality, spaced apart relationship; in some embodiments, the protrusions are provided in a plurality, the plurality of protrusions being spaced apart, and a gap between two adjacent protrusions forming a recess.

In some embodiments, referring still to fig. 1, the weight-reducing holes 411 are provided with recesses and/or protrusions along the radial direction of the rotor sheet 410 on both the first side wall 412 and the second side wall 413, i.e., the first side wall 412 is provided with recesses and/or protrusions and the second side wall 413 is provided with recesses and/or protrusions. No recesses and/or protrusions are provided on both sidewalls of the lightening holes 411 in the circumferential direction of the rotor sheet 410, i.e., no serration is provided on both sidewalls of the lightening holes 411 in the circumferential direction of the rotor sheet 410. Taking the first sidewall 412 being close to the mounting hole 415 and the second sidewall 413 being far from the mounting hole 415 as an example, the effect is as follows: when the rotor punching 410 works, the air in the lightening hole 411 has a tendency to move towards a direction away from the mounting hole 415 under the action of centrifugal force, so that the air distribution in the lightening hole 411 can be slightly changed, wherein the air on the side away from the mounting hole 415 in the lightening hole 411, namely, the second side wall 413 is dense, the air on the side close to the mounting hole 415 in the lightening hole 411, namely, the first side wall 412 is thin, the heat transfer effect on the second side wall 413 is higher than that of the first side wall 412, and therefore, the concave and/or convex arrangement of the first side wall 412 can further improve the heat dissipation effect of the rotor. The second side wall 413 is close to the mounting hole 415, and the recess and/or the protrusion provided on the second side wall 413 can enhance the heat convection area of the rotor sheet 410 and the air.

In other embodiments, the weight-reducing holes 411 also have recesses and/or protrusions along both sidewalls of the rotor sheet 410 in the circumferential direction.

In some embodiments, referring to fig. 1, the first side wall 412 and the second side wall 413 are provided with protrusions, which not only can increase the heat dissipation area, but also can increase the strength of the rotor sheet 410, and the protrusions are provided with grooves 414, that is, the grooves 414 are located at the protrusions, and the grooves 414 form recesses to further increase the heat dissipation area of the rotor sheet 410 in contact with air.

In some embodiments, the spacing of the two grooves 414 disposed along the radial direction of the rotor sheet 410 is less than the spacing of the first sidewall 412 and the second sidewall 413 to increase the strength of the rotor sheet 410 along the radial direction; wherein the pitch of the two grooves 414 disposed in the radial direction of the rotor sheet 410 refers to the pitch between the bottoms of the two grooves 414 disposed in the radial direction of the rotor sheet 410.

In some embodiments, referring still to fig. 1, the lightening hole 411 is a rectangular hole, and the first sidewall 412 and the second sidewall 413 are long sides of the rectangular hole, i.e., the long sides of the rectangular hole extend along the circumference of the rotor sheet 410, and the short sides of the rectangular hole extend along the radial direction of the rotor sheet 410. Since the rotor sheet 410 needs to be provided with the guide holes 417 for installing the squirrel cage, the guide holes 417 are located at the outer side of the lightening holes 411 along the radial direction of the rotor sheet 410, so in order to improve the strength of the rotor sheet 410, the radial dimension of the lightening holes 411 along the rotor sheet 410 is limited by the guide holes 417 and the installation holes 415, so that the wide sides of the rectangular holes extend along the radial direction, and the size is smaller so as to meet the arrangement requirements of the lightening holes 411, the installation holes 415 and the guide holes 417. The rectangular hole length extends along the circumferential direction of the rotor punching sheet 410, so that the lightening holes 411 have a larger contact area with air, and the space utilization rate is improved.

In some embodiments, the protrusion is provided with a plurality of grooves 414, the plurality of grooves 414 being spaced apart. The number of the grooves 414 may be two, three, four, etc., and the grooves 414 penetrate in the thickness direction of the rotor sheet 410. When the first side wall 412 and the second side wall 413 are each provided with a protrusion, a plurality of grooves 414 on the protrusions are spaced apart in the circumferential direction of the rotor sheet 410.

In some embodiments, the grooves 414 are rectangular grooves 414. In other embodiments, referring to FIG. 1, the grooves 414 are triangular grooves, which are not prone to dead zones, facilitating convective heat transfer between the air and the rotor.

In some embodiments, referring to fig. 1, the rotor plate 410 is provided with a plurality of guide holes 417 into which the cage bars extend, the plurality of guide holes 417 are circumferentially spaced around the mounting hole 415, and the guide holes 417 are located radially outward of the lightening holes 411 along the rotor plate 410.

In some embodiments, referring to fig. 1, the rotor sheet 410 is provided with a rotation stopping protrusion 416 located on a wall of the mounting hole 415, and the rotating shaft 100 is provided with a rotation stopping groove matched with the rotation stopping protrusion 416, and the rotation stopping protrusion 416 is matched with the rotation stopping groove to prevent the rotor sheet 410 and the rotating shaft 100 from generating relative motion in a circumferential direction.

In a second aspect of the present application, an electric motor is provided, including a rotor assembly and a stator assembly, referring to fig. 2 and 3, the rotor assembly includes a rotating shaft 100 and a plurality of rotor punching sheets 410 of the first aspect stacked in sequence, and weight-reducing holes 411 of the plurality of rotor punching sheets 410 are correspondingly communicated one by one to form a weight-reducing channel 420; the rotating shaft 100 is installed in the installation hole 415; the stator assembly is sleeved outside the plurality of rotor laminations 410.

The rotor assembly includes a plurality of rotor laminations 410 forming a rotor core 400, and the rotor shaft 100 is mounted in the rotor core 400.

The stator assembly includes a stator core 400 and stator windings, which generate a magnetic field when energized, and the rotor assembly rotates under the magnetic field of the stator assembly, thereby converting electrical energy into kinetic energy.

In some embodiments, the rotor assembly further comprises a squirrel cage having two end rings 500 positioned at axial ends of the plurality of rotor laminations 410, the end rings 500 being positioned outside the lightening holes 411 in an axial projection of the shaft 100. The lightening holes 411 are exposed out of the end ring 500, so that the lightening holes 411 are communicated with the motor cavity, and when the rotor assembly works, air in the motor shell and air in the lightening holes 411 generate convection, and heat of the rotor is taken away.

Specifically, after the plurality of rotor sheets 410 are stacked in sequence, the guide holes 417 corresponding to the plurality of rotor sheets 410 are sequentially communicated to form a channel for inserting the guide bars of the squirrel cage, and the two end rings 500 of the squirrel cage are located at two ends of the rotor core 400 in the axial direction.

The rotating shaft 100 is provided with a rotation stopping groove extending along the axial direction of the rotating shaft, the rotation stopping protrusions 416 of the rotor punching sheets 410 are corresponding in position, the rotation stopping protrusions 416 corresponding to the positions form a rotation stopping structure matched with the supporting groove, namely the iron core 400 is provided with a rotation stopping structure, and the rotation stopping structure is positioned in the rotation stopping groove so as to limit relative movement between the rotating shaft 100 and the iron core 400 along the circumferential direction. The rotation stopping structure of the iron core 400 may be provided with a plurality of rotation stopping structures, the rotation stopping grooves of the corresponding rotating shaft 100 are the same as the rotation stopping structures in number, and the rotation stopping grooves are in one-to-one correspondence with the rotation stopping structures.

In some embodiments, the shaft 100 is provided with a shoulder 110, the rotor assembly further includes a stop collar 200 connected to the shaft 100, a plurality of rotor punching sheets 410 are located between the shoulder 110 and the stop collar 200, and the weight reducing holes 411 are exposed from the shoulder 110 and the stop collar 200. Through the shaft shoulder 110 and the limiting rings 200, the two axial ends of the rotor core 400 are limited, and the rotor core 400 and the rotating shaft 100 are prevented from generating relative motion along the axial direction. The rotor core 400 is in clearance fit with the rotating shaft 100, so that the rotor core 400 is sleeved outside the rotating shaft 100, and the limiting ring 200 can be a pressing ring or a pressing ring, and the pressing ring or the pressing ring is in interference fit with the rotating shaft 100.

In some embodiments, the rotor assembly further includes two compression rings 300, where the two compression rings 300 are respectively located at two ends of the rotor core 400 along the axial direction, and the two compression rings 300 are located between the shaft shoulder 110 and the limiting ring 200. The axial projections of the shaft shoulder 110, the compression ring 300 and the limiting ring 200 along the rotating shaft 100 are all located outside the lightening hole 411.

In some embodiments, the motor further includes a housing having a receiving cavity, the rotor assembly and the stator assembly are both disposed within the receiving cavity, the housing having cooling channels for circulating cooling fluid and inlets and outlets communicating with the cooling channels, the cooling channels being disposed about the rotor shaft 100 and serpentine in a circumferential direction of the housing. When the motor works, heat generated by the stator assembly is transferred to the shell; and meanwhile, convection air in the motor cavity can be in contact with the cavity wall of the accommodating cavity so as to transfer heat to the shell, the shell transfers the heat to a cooling medium in the cooling liquid flow channel, and the cooling medium takes away the heat.

The cooling flow passage is arranged in a serpentine manner, so that the contact area between the cooling flow passage and the shell can be sufficiently increased, and the heat dissipation effect is improved.

In some embodiments, the shell comprises an inner shell and an outer shell, the inner shell comprises a column section and annular protrusions connected to two ends of the column section in the axial direction, a plurality of protrusions arranged at intervals are arranged on the outer peripheral surface of the column section, the inner shell is sleeved on the outer shell, and the column section, the annular protrusions, the protrusions and the inner shell frame encircle to form the cooling flow channel.

In some embodiments, the motor further comprises two end caps, the two end caps are respectively connected to two ends of the housing in the axial direction, and the rotor assembly, the stator assembly, the housing and the two end caps enclose a motor cavity.

In some embodiments, the two ends of the rotating shaft are connected with bearings, the two end covers are provided with bearing mounting holes, and the two bearings are respectively mounted in the two bearing mounting holes.

In a second aspect of the application, an embodiment is provided of a vehicle comprising the electric machine of the second aspect.

The vehicle further comprises a reducer, to which the rotating shaft 100 of the motor is force-fitted a reduction shaft.

In some embodiments, one end cap of the motor is the housing of the reducer.

Temperature rise simulation analysis is performed on motors formed by rotor punching plates without lightening holes (scheme 1), rotor punching plates with lightening holes but without saw tooth structures (scheme 2) and rotor punching plate structures (scheme 3) provided by the embodiment of the application respectively, and the results are shown in table 1:

TABLE 1

As can be seen from table 1, the rotor core was 186 ℃, the cage was 186 ℃, the shaft was 185 ℃ and the bearing was 127 ℃ in the scheme that no lightening holes were provided in the rotor punching. For the scheme that the rotor punching sheet is only provided with a lightening hole but has no saw tooth structure, the rotor iron core is 168 ℃, the squirrel cage is 168 ℃, the rotating shaft is 165 ℃, and the bearing is 116 ℃. For the motor formed by the rotor punching sheet provided by the embodiment of the application, the rotor core is 162 ℃, the squirrel cage is 159 ℃, the rotating shaft is 159 ℃, and the bearing is 113 ℃, so that the saw tooth structure is arranged in the lightening hole on the basis of the scheme 2, the heat convection area is increased, the heat dissipation is enhanced, and the temperatures of the rotating shaft, the rotor core, the squirrel cage and the bearing are reduced.

The rotor punching sheet 410, the motor and the vehicle provided by the application have at least the following advantages:

(1) Weight reducing holes 411 are formed in the rotor punching sheet 410, so that the weight of the rotor is optimized, and the power density of the motor is effectively improved.

(2) The inner wall of the lightening hole 411 is of a sawtooth structure, so that the convection heat exchange area of the rotor and air is increased, and the heat dissipation of the rotor is more sufficient.

(3) The shoulder 110 and the limiting ring 200 of the rotor assembly are not covered with the lightening holes 411, so that the lightening holes 411 of the rotor punching sheet 410 can exchange heat with air convection in the motor cavity, and the heat dissipation effect is ensured.

In the present application, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" indicate orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application.

In the present application, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more features. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the application, the scope of which is defined by the claims and their equivalents.

Claims (10)

1. The rotor punching sheet is characterized in that the rotor punching sheet is provided with a lightening hole and a mounting hole for a rotor rotating shaft to extend in, the lightening hole is provided with a plurality of lightening holes, the lightening holes are wound outside the mounting hole along the circumferential direction of the mounting hole, the lightening holes are arranged at intervals, and the hole wall of the lightening hole is provided with a recess and/or a protrusion.

2. A rotor punching according to claim 1, characterized in that the weight-reducing holes are provided with the recesses and/or protrusions in both the first and second side walls in the radial direction of the rotor punching.

3. The rotor punching of claim 2, wherein the first and second side walls are each provided with the projection, the projection being provided with a groove; the distance between the two grooves arranged along the radial direction of the rotor punching sheet is smaller than the distance between the first side wall and the second side wall.

4. The rotor punching of claim 2, wherein the lightening holes are rectangular holes and the first and second side walls are each a long side of the rectangular holes; the bulge is provided with a plurality of grooves, and the grooves are distributed at intervals; the grooves are triangular grooves.

5. A rotor according to any one of claims 1-4, characterized in that the rotor is provided with a plurality of guide holes into which cage bars extend, a plurality of said guide holes being circumferentially spaced around the mounting hole, said guide holes being located radially outside the lightening hole in the rotor.

6. An electric machine, comprising:

The rotor assembly comprises a rotating shaft and a plurality of rotor punching sheets according to any one of claims 1-5 which are stacked in sequence, wherein the weight reducing holes of the rotor punching sheets are communicated in one-to-one correspondence; the rotating shaft is arranged in the mounting hole;

and the stator assembly is sleeved outside the rotor punching sheets.

7. The motor of claim 6, wherein the rotor assembly further comprises a squirrel cage having two end rings located at axial ends of the plurality of rotor laminations, the end rings being located outside the lightening holes in an axial projection of the shaft.

8. The motor of claim 7, wherein the shaft is provided with a shoulder, the rotor assembly further comprises a stop collar coupled to the shaft, the plurality of rotor laminations are positioned between the shoulder and the stop collar, and the lightening holes are exposed to the shoulder and the stop collar.

9. The electric machine of claim 6, further comprising a housing having a receiving cavity, wherein the rotor assembly and the stator assembly are both positioned within the receiving cavity, wherein the housing has cooling channels for circulation of cooling fluid and inlet and outlet ports in communication with the cooling channels, wherein the cooling channels are disposed about the axis of rotation and are serpentine in a circumferential direction of the housing.

10. A vehicle comprising an electric machine as claimed in any one of claims 6 to 9.