CN219718023U

CN219718023U - Balance disc, driving motor and vehicle

Info

Publication number: CN219718023U
Application number: CN202321280205.0U
Authority: CN
Inventors: 罗旋
Original assignee: Xiaomi Automobile Technology Co Ltd
Current assignee: Xiaomi Automobile Technology Co Ltd
Priority date: 2023-05-24
Filing date: 2023-05-24
Publication date: 2023-09-19
Anticipated expiration: 2033-05-24

Abstract

The present disclosure relates to a balance disc, a driving motor and a vehicle, wherein the balance disc (3) is provided with a first end face and a second end face, the first end face is used for being abutted against a rotor core (21), a convex key (311) is arranged on the first end face, and the convex key (311) protrudes out of the first end face along the axial direction so as to be matched with a limiting hole (200) on the rotor core (21). Through adjusting the setting position of protruding key to on the terminal surface of balance disc, through the cooperation in spacing hole on protruding key and the rotor core, not only can realize the circumference locking of balance disc and rotor core, effectively solve the problem that the balanced disc inner circle stress is concentrated under the high rotational speed operation simultaneously, can guarantee the intensity of rotor silicon steel sheet under the high rotational speed and the intensity of balance disc, effectively realize driving motor rotational speed promotion to further promote current driving motor power density.

Description

Balance disc, driving motor and vehicle

Technical Field

The disclosure relates to the technical field of balance discs, and in particular relates to a balance disc, a driving motor and a vehicle.

Background

The balance disc is an important component in the driving motor, and the performance of the balance disc in various aspects such as self strength, assembly with a rotor core and the like has great influence on the driving motor. In the related art, the balance disc is positioned in the circumferential direction by adopting a convex key designed on the inner ring, the convex key is matched with a key groove on the rotating shaft for positioning, but after the rotating speed is increased, the transition area of the convex key of the inner ring of the balance disc can generate larger stress concentration, and under the action of centrifugal force, the inner ring is easy to tear in the transition area of the convex key, so that the connection failure occurs.

Disclosure of Invention

To overcome the problems in the related art, the present disclosure provides a balance disc, a driving motor, and a vehicle.

According to a first aspect of the embodiments of the present disclosure, there is provided a balance disc, the balance disc has a first end face and a second end face, the first end face is used for abutting against a rotor core, a protruding key is disposed on the first end face, and the protruding key protrudes from the first end face along an axial direction so as to be matched with a limiting hole on the rotor core.

Optionally, the protruding key is in interference fit with the limiting hole.

Optionally, the balancing disc has a central hole through which the rotating shaft passes, the balancing disc is configured in an annular structure having an inner ring and an outer ring, the protruding key is disposed between the inner ring and the outer ring, and the protruding key is a plurality of protruding keys arranged at intervals along the circumferential direction, and has at least two protruding keys arranged in the same radial direction and oppositely arranged.

Optionally, the convex key is configured as a trapezoid structure, and an upper bottom and a lower bottom of the trapezoid structure are respectively arranged perpendicular to the radial direction of the balance disc.

Optionally, the four corners of the trapezoid are configured as rounded corners.

Optionally, the balance disc is provided with a central hole for the rotating shaft to pass through, a stress release groove is arranged on the first end face and positioned on the periphery of the central hole, and the stress release groove is radially and outwards opened by the peripheral wall of the central hole so as to be communicated with the central hole.

Optionally, the stress release grooves are of multi-section arc structures arranged at intervals along the circumferential direction, oil guide grooves are arranged between two adjacent sections of the stress release grooves, and the oil guide grooves extend along the radial direction and are open at one end so as to be communicated with an oil inlet on the rotating shaft.

Optionally, a plurality of arc-shaped oil channels are further arranged on the first end face, the outer diameter of the stress relief groove is R1, the outer diameter of the arc-shaped oil channel is R4, wherein,

R1≤R4-a-2d，

a is the width of the arc-shaped oil duct in the radial direction, b is the diameter of the dynamic balance calibration drill bit, D is the residual wall thickness of the dynamic balance calibration area, d=d-b, and D is the wall thickness of the middle part of the balance disc.

Optionally, the second end surface has a middle portion and a weight-reducing portion located at an outer periphery of the middle portion, wherein a dimension of the weight-reducing portion in an axial direction is smaller than a dimension of the middle portion in the axial direction.

Optionally, the weight-reducing portion is provided with a plurality of radial ribs extending radially outwards from the middle portion, the weight-reducing portion is divided into a plurality of weight-reducing areas by the plurality of radial ribs, and an oil outlet groove extending radially is formed in a position, corresponding to the radial ribs, on the first end face so as to avoid the weight-reducing areas.

Optionally, a plurality of arc-shaped oil channels are arranged on the first end face, the outer diameter of the middle part is R2, the outer diameter of the arc-shaped oil channels is R4, wherein,

R2≥R4+H，

and H is the wall thickness of the weight-reducing region in the radial direction.

Optionally, the width of the radial rib is c, and the width of the arc-shaped oil duct is a, wherein c is more than or equal to a+2H.

According to a second aspect of the present disclosure, there is also provided a drive motor including a rotor, a stator, and the balance disc described above.

According to a third aspect of the present disclosure, there is also provided a vehicle including the above-described drive motor.

The technical scheme provided by the embodiment of the disclosure can comprise the following beneficial effects: in the balance disc provided by the disclosure, the setting position of the convex key is adjusted to the end face of the balance disc, through the cooperation of the convex key and the upper limit hole of the rotor core, the circumferential locking of the balance disc and the rotor core can be realized, meanwhile, the problem of stress concentration of the inner ring of the balance disc under high-rotation-speed running is effectively solved, the strength of the rotor silicon steel sheet and the strength of the balance disc under high rotation speed can be ensured, the rotation speed lifting of the driving motor is effectively realized, and the power density of the current driving motor is further improved. In addition, the traditional production process can be adopted, the production is simple, and the process is mature.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

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

Fig. 1 and 2 are schematic diagrams of a balancing disk shown according to an exemplary embodiment.

Fig. 3 and 4 are schematic views of a balance disc shown according to another exemplary embodiment.

Figure 5 is a side view of the balance disc of the embodiment shown in figure 3.

Fig. 6 is a perspective view of the balance disc of the embodiment shown in fig. 3.

Fig. 7 and 8 are front views of the balance disc of the embodiment shown in fig. 3.

Fig. 9 is an exploded view of a rotor in a driving motor according to an exemplary embodiment.

Fig. 10 is a schematic diagram showing a cooling liquid flow path in a driving motor according to an exemplary embodiment.

Description of the reference numerals

21-a rotor core; 200-limiting holes; 210-a receiving groove; 211-flow channel; 22-permanent magnets; 3-balancing discs; 30-a central hole; 31-a first end face; 311-convex bond; 312-stress relief grooves; 32-a second end face; 301-middle; 302-a weight-reduction portion; 3011-radial ribs; 303-an oil guide groove; 304-an oil guide hole; 305-arc oil duct; 306-an oil throwing hole; 307-oil outlet groove; 4-rotating shaft; 41-an oil inlet hole; 5-locking member.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present disclosure as detailed in the accompanying claims.

It should be noted that, all actions of acquiring signals, information or data in the present utility model are performed under the condition of conforming to the corresponding data protection rule policy of the country of the location and obtaining the authorization given by the owner of the corresponding device.

In this disclosure, unless otherwise indicated, terms of orientation such as "axial," "circumferential," "radial" are used to generally refer to definitions relative to the central axis of the balance disc, and "inner," "outer" refer to inner and outer of the corresponding component profile. The use of the terms first, second, etc. are used for the purpose of distinguishing between different elements and not necessarily for the sake of order or importance. Furthermore, in the following description, when referring to the drawings, the same reference numerals in different drawings denote the same or similar elements unless otherwise explained.

In the related art, the rotor core 21 is formed of a plurality of silicon steel sheets arranged in a stacked manner, the strength of the silicon steel sheets at high speed is a main bottleneck in the current main stream high-speed driving motor rotating speed section, the stress level of the balance disc can be satisfied by using a common die-casting material, and the heat dissipation of the permanent magnet 22 can be solved through a lightening hole or through lightening hole oil passing.

In the related embodiments of the present disclosure, in terms of strength of the silicon steel sheet, the stress level of the silicon steel sheet at high speed is generally reduced by optimizing or applying a protective sleeve, and the stress optimization scheme is mostly based on performing local stress optimization on the silicon steel sheet of the motor rotor, including performing rounded smooth transition on a region with a larger part of stress, performing weight reduction on a part of region to reduce centrifugal force, and the like, where the current mainstream rotor design performs local stress optimization. However, the local stress optimization can only realize the tiny increase of the rotating speed, and can not greatly increase the rotating speed of the motor, and the technical scheme can not be calculated as an effective solution of the high-speed motor.

In addition, the rotor rotation speed is improved by wrapping carbon fibers on the outer ring of the motor rotor, which is common to high-speed motor rotors such as a turbo compressor, and the integrity of the internal structure of the rotor 2 at high speed is protected by wrapping carbon fibers on the outer edge of the motor rotor. However, the carbon fiber wrapping scheme can increase the air gap between the stator and the rotor 2, so that part of motor performance is lost, the carbon fiber production beat is slow, the price is high, and the production equipment is complex.

Based on the above, if it is desired to further increase the motor rotation speed, not only the strength of the silicon steel sheet but also the balance disc strength is required to be paid attention, and the heat dissipation of the permanent magnet 22 is required to be further enhanced. Thus, a complete solution for the architecture is needed.

To solve the above-mentioned problem, as shown in fig. 1 to 10, the present disclosure provides a driving motor, which includes a stator 1, a rotor 2, a balance disc 3 and a rotating shaft 4, wherein the stator 1 is sleeved on the periphery of the rotor 2, the rotor 2 includes a rotor core 21 and a permanent magnet 22 disposed in the rotor core 21, the rotor core 21 has a first end face and a second end face, the balance disc is two and is respectively abutted to the first end face and the second end face, and the first balance disc, the rotor core 21 and the second balance disc are sequentially sleeved on the rotating shaft 4 along the axial direction and are fixed by a locking member 5 at the end part. Here, it should be noted that the driving motor may be a permanent magnet synchronous motor, and may be applied to devices in different industries such as vehicles, metallurgy, environmental protection, etc., which is not limited in this disclosure. The locking piece 5 can be a nut, a rivet pressing ring, a clamp spring, an interference ring and the like, and is matched with a stop shoulder of the rotating shaft 4 to realize axial fixing and locking of the balance disc and the rotor core 21, the first balance disc and the second balance disc can be of the same structure or different, and can be made of steel, stainless steel, aluminum alloy and the like.

In the high-speed driving motor provided by the disclosure, the following improvements are mainly made, the stress of the balance disc 3 is reduced, the permanent magnet 22 is directly radiated, the problems of the strength of the rotor core 21, the strength of the balance disc 3, the radiation of the permanent magnet 22 and the like at high rotation speed are solved, and the three aspects are respectively described in detail below to form a complete and systematic complete solution.

In the first aspect, in the technical scheme of reducing the stress of the balance disc 3, the strength of the balance disc still meets the requirement in the current main current driving rotation speed stage, but the strength of the balance disc becomes a constraint factor along with the further improvement of the rotation speed. In the related embodiment of the disclosure, the positioning mode of the rotating shaft 4 and the balance disc 3 in the circumferential direction adopts that convex keys are arranged on the inner ring of the balance disc 3, key grooves are formed in the peripheral wall of the rotating shaft 4, and the balance disc 3 and the rotating shaft 4 are locked in the circumferential direction through the cooperation of the convex keys and the key grooves. After the rotating speed is increased, larger stress concentration can be generated in the key groove transition area of the inner ring of the balance disc, and the inner ring is easy to tear in the key groove transition area under the action of centrifugal force, so that failure occurs. In order to solve the problem, in the related embodiment, the balance disc and the rotating shaft 4 are in interference fit for circumferential positioning, however, especially when the balance disc is made of steel or stainless steel, due to high material density, the self structural strength is difficult to meet the scene under high speed due to the action of centrifugal force at high speed, and the inner ring is greatly increased in tendency to expand outwards due to the high density, so that the interference is required to be large, the strength of the enlarged interference becomes a bottleneck, and the high-speed scene is difficult to meet due to the combination.

In order to solve the defects of the circumferential limit structure of the balance disc and the outer circumferential surface of the rotating shaft 4, as shown in fig. 1 and 2, the present disclosure provides a balance disc 3, the balance disc 3 has a first end surface 31 and a second end surface 32, the first end surface 31 is used for being abutted against the rotor core 21, a convex key 311 is arranged on the first end surface 31, the convex key 311 protrudes out of the first end surface along the axial direction so as to be matched with a limit hole 200 on the rotor core 21, that is, in the balance disc 3 provided by the present disclosure, the setting position of the convex key 311 is adjusted, through the matching of the convex key 311 and the limit hole 200, not only circumferential locking of the balance disc and the rotor core 21 can be realized, but also the problem of stress concentration of the inner ring of the balance disc under high-rotation operation can be effectively avoided, the strength of the rotor silicon steel sheet under high-rotation-speed can be ensured, the rotation speed of the driving motor is effectively improved, and the current driving motor power density is further improved. In addition, the traditional production process can be adopted, the production is simple, and the process is mature.

The protruding key 311 and the limiting hole 200 may have any suitable structure. The protruding key 311 is disposed on the first end surface 31 of the balance disc 3 facing the rotor core 21, and the limiting hole 200 is opened on the end surface of the rotor core 21. Through the cooperation of protruding key 311 and spacing hole 200, can realize that balance plate 3 and rotor core 21's circumference is fixed, a plurality of spacing holes 200 can be seted up to rotor core 21's terminal surface, and partial spacing hole 200 can be used as the lightening hole, and spacing hole 200 and lightening hole can adopt the same shape, also can design alone.

In the present disclosure, the protruding key 311 and the limiting hole 200 may adopt an interference fit manner, so that relative movement between the balance disc 3 and the rotor core 21 in the circumferential direction and the axial direction can be prevented when the balance disc 3 and the rotor core 21 rotate, in addition, since the rotor core 21 and the rotating shaft 4 adopt an interference fit manner, the two may be fixed in a large interference or key slot fit manner, and accordingly, circumferential fixation of the balance disc 3 and the shaft can also be realized. The balance disc 3 has a central hole 30 through which the rotation shaft 4 passes, the balance disc 3 may be configured as an annular structure, the protruding keys 311 may be disposed between an inner ring and an outer ring of the annular structure, and the protruding keys 311 may be a plurality of arranged at intervals in the circumferential direction, and at least have two arranged in the same radial direction and opposite to each other, i.e., the protruding keys 311 are symmetrically arranged with respect to the axis, preferably, the number is 2, 180 ° arranged, of course, a plurality of, more than 2, uniformly arranged in the circumferential direction to perform a better circumferential fixing effect, of course, the protruding keys 311 and the limiting holes 200 may take any suitable shape, as shown in fig. 1, the protruding keys 311 may be a plurality of arranged at intervals in the circumferential direction, and the protruding keys 311 may be a trapezoid structure, and the upper bottom and the lower bottom of the trapezoid structure are respectively arranged perpendicular to the radial direction of the balance disc 3, and the limiting holes 200 may be trapezoid holes accordingly. In other embodiments, the protruding key 311 may have a cylindrical, square, or other structure, which is not limited by the present disclosure. In addition, in order to facilitate assembly, the four corners of the trapezoid structure are designed as fillets, so that the protruding key 311 and the limiting hole 200 are convenient to install.

Further, in order to further alleviate the centrifugal tearing effect of the inner ring of the balancing disc 3 at high speed, as shown in fig. 3 and 4, in the present disclosure, the balancing disc 3 has a central hole 30 through which the rotating shaft 4 passes, a stress release groove 312 is disposed on the first end surface 31 and located at the outer periphery of the central hole 30, and the stress release groove 312 is opened radially outwards from the peripheral wall of the central hole 30 to be communicated with the central hole 30, so that the stress at high rotation speed can be effectively released while ensuring the connection stability with the rotating shaft 4.

The stress release grooves 312 may be multi-segment arc structures arranged at intervals along the circumferential direction, preferably three stress release grooves 312 are shown in the figure, an oil guiding groove 303 is arranged between two adjacent stress release grooves 312, and the oil guiding groove 303 extends along the radial direction and is open at one end so as to be communicated with the oil inlet hole 41 on the rotating shaft 4. Regarding the oil guide groove 303, and the oil guide hole 304, the arc-shaped oil passage 305, the oil discharge groove 307, and the oil slinger hole 306, which will be described later, all relate to the flow path of the cooling liquid, and their functions will be described later in detail. The oil guide groove 303, the arc-shaped oil duct 305 and the oil outlet groove 307 can be designed to have the same width a, and can be designed according to the flow of the cooling liquid, for example, a can be 2-6mm, and of course, different width designs can also be adopted.

As shown in fig. 7 and 8, the first end surface 31 is provided with a plurality of arc-shaped oil passages 305, the outer diameter of the stress relief groove 312 is R1, the outer diameter of the arc-shaped oil passage 305 is R4, wherein,

R1≤R4-a-2d，

a is the width of the arc-shaped oil duct 305 in the radial direction, b is the dynamic balance calibration drill diameter, D is the residual wall thickness of the dynamic balance calibration area, d=d-b, as shown in fig. 5, D is the wall thickness of the middle part 301 of the balance disc, preferably r1=r4-a-2D, and the dynamic balance calibration of the balance disc adopts a weight-removing method, and through the calibration balance and the above-mentioned size design, the rotation balance of the balance disc can be ensured and the problems of stress concentration and the like can be solved.

After the convex key 311 and the limiting hole 200 are arranged on the end face, the stress concentration degree of the inner ring of the balance disc can be improved, however, as the balance disc of the oil cooling motor is further provided with the oil passage groove (which is explained in detail when the permanent magnet 22 is directly cooled), larger stress still exists at the position close to the inner ring oil passage groove at high rotation speed, further, the balance disc is subjected to weight reduction treatment, as shown in fig. 2, the second end face of the balance disc is provided with the middle part 301 and the weight reduction part 302 positioned at the periphery of the middle part 301, and the dimension of the weight reduction part 302 in the axial direction is smaller than that of the middle part 301. The stress level of the balance disc 3 close to the groove of the inner ring can be greatly improved by adopting the balance disc outer ring weight reduction structure.

In another embodiment of the present disclosure, as shown in fig. 4 and 6, the weight-reducing portion 302 is provided with a plurality of radial ribs 3011 extending radially outward from the middle portion 301, the plurality of radial ribs 3011 divide the weight-reducing portion 302 into a plurality of weight-reducing regions, and oil outlet grooves 307 extending radially are formed on the first end surface 31 at positions corresponding to the radial ribs 3011 so as to avoid the weight-reducing regions. The more the balancing disk 3 is reduced in weight, the more the stress level at high speeds can be reduced. The weight is reduced while the structural strength is ensured, and the stress level of the balance disc can be improved. In addition, the end of the radial rib 3011 is provided with an oil slinger 306 which communicates with the oil outlet groove 307.

Regarding the dimensional proportion of the weight-reduction portion 302, as shown in fig. 7 and 8, a plurality of arc-shaped oil passages 305 are provided on the first end surface 31, the outer diameter of the intermediate portion 301 is R2, the outer diameter of the arc-shaped oil passage 305 is R4, wherein,

R2≥R4+H，

as shown in fig. 5, H is the wall thickness of the weight-reduction region in the radial direction. Here, H is preferably die cast with an optimal casting thickness, for example, 2-4mm, to determine the weight reduction ratio according to the position of the arc-shaped oil passage 305 and the wall thickness of the weight reduction region.

Radial ribs 3011 may be of any suitable configuration. As shown in FIG. 8, radial ribs 3011 have a width c and arcuate oil gallery 305 has a width a, where c is equal to or greater than a+2H. The radial ribs 3011 may be configured to gradually decrease in width from inside to outside, where the width c is the minimum width, so that the overall rigidity of the balance disc can be ensured.

In the technical scheme of directly cooling the permanent magnet 22, in the process of rotating the rotor 2 at a high speed, the permanent magnet 22 generates serious heat, and the permanent magnet is demagnetized due to overhigh temperature, and if the rotating speed of the driving motor needs to be greatly increased, the heat dissipation of the permanent magnet 22 becomes a limiting condition for designing the high-speed driving motor. To solve this problem, as shown in fig. 7, the rotor core 21 is provided with a receiving groove 210 for fixing the permanent magnet 22, the inner wall of the receiving groove 210 is provided with a fixing portion for fixing the permanent magnet 22, and a flow passage 211 for flowing a cooling liquid is formed between the inner wall of the receiving groove 210 and the permanent magnet 22. Here, the cooling liquid may be water-cooled or oil-cooled, or may be other cooling medium, and an oil-cooled motor will be described in detail herein.

As shown in fig. 9, the rotating shaft 4 is provided with a plurality of oil inlet holes 41, the two balancing discs 3 are respectively provided with an oil guiding groove 303 and an arc oil duct 305, the rotor core 21 may be provided with an oil guiding hole 304, the balancing discs may also be provided with oil guiding holes 304, the arc oil duct 305 is used for communicating the flow channels 211 of the two adjacent accommodating grooves 210, and the positions of the oil guiding holes 304 and the arc oil duct 305 correspond. In this way, the flow path of the oil for cooling the permanent magnet 22 is that the hollow rotating shaft 4 is filled with cooling oil, the cooling oil is driven to rotate along the inner wall of the rotating shaft 4 along with the rotation of the rotor 2, under the centrifugal force and the oil pressure of the cooling oil, the cooling oil enters an oil guiding groove 303 formed by the balance disc and the rotor core 21 through an oil inlet hole 41, as shown in fig. 10, the cooling oil flows into an oil guiding hole 304 through the oil guiding groove 303, enters the other end (for example, flows from the first end face to the second end face) of the rotor core 21, enters the flow channel 211 through an arc-shaped oil duct 305, cools the permanent magnet 22, returns to the first end face of the rotor core 21 through the flow channel 211, passes through an oil outlet groove 307, and finally is sprayed to the end winding of the stator 1 through an oil throwing hole 306 in an oblique direction. Here, there may be various sources of cooling oil in the convection passage 211 and flow paths of the oil passage, not limited to the embodiments provided in the present disclosure.

The following table shows that the temperature of the permanent magnet 22 can be obviously reduced by directly feeding the oil to the permanent magnet 22, and the problems of demagnetization and the like caused by overhigh temperature of the permanent magnet 22 can be avoided by comparing the temperature of the permanent magnet 22 in the three schemes of directly feeding the oil to the permanent magnet 22, feeding the oil to the rotor core 21 and feeding the oil to the rotating shaft 4.

Through designing the positions and the sizes of the oil guide groove 303, the arc-shaped oil duct 305 and the oil outlet groove 307 on the balance disc, the flow of cooling liquid can be ensured, meanwhile, the rotation balance of the balance disc can be ensured, the weight reduction design is realized, and the integral stress level of the balance disc is improved.

According to another aspect of the present disclosure, there is further provided a vehicle, the vehicle includes the driving motor described above, the driving motor may be applied to a new energy automobile, high-rotation-speed driving may be achieved, and power density of the driving motor is improved.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure. This application is intended to cover any adaptations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

It is to be understood that the present disclosure is not limited to the precise arrangements and instrumentalities shown in the drawings, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. The balance disc is characterized by comprising a first end face and a second end face, wherein the first end face is used for being abutted against the rotor core, a convex key is arranged on the first end face and protrudes out of the first end face along the axial direction so as to be matched with a limiting hole on the rotor core.

2. The balance disc of claim 1, wherein the male key is an interference fit with the limiting aperture.

3. The balance disc according to claim 1, wherein the balance disc has a center hole through which the rotation shaft passes, the balance disc is configured as an annular structure having an inner ring and an outer ring, the protruding key is provided between the inner ring and the outer ring, and the protruding key is provided in plurality at intervals in a circumferential direction, and has at least two arranged in the same radial direction and oppositely arranged.

4. The balance disc of claim 1, wherein the male key is configured in a trapezoidal structure, and an upper base and a lower base of the trapezoidal structure are respectively arranged perpendicularly to a radial direction of the balance disc.

5. The balance disk of claim 4 wherein four corners of the trapezoid are configured as rounded corners.

6. The balance disc of claim 1, wherein the balance disc has a central hole through which the rotating shaft passes, and wherein the first end face is provided with a stress relief groove on the outer periphery of the central hole, the stress relief groove being opened radially outward from the peripheral wall of the central hole so as to communicate with the central hole.

7. The balance disc of claim 6, wherein the stress relief grooves are of a multi-segment arc-shaped structure arranged at intervals along the circumferential direction, and oil guide grooves are arranged between two adjacent segments of the stress relief grooves, extend along the radial direction and are open at one end so as to be communicated with oil inlet holes in the rotating shaft.

8. The balance disc of claim 6, wherein the first end face is further provided with a plurality of arcuate oil channels, the stress relief groove having an outer diameter R1 and the arcuate oil channels having an outer diameter R4, wherein,

R1≤R4-a-2d，

9. The balance disc of any of claims 1-8, wherein the second end face has a middle portion and a weight-reduction portion located at an outer periphery of the middle portion, wherein a dimension of the weight-reduction portion in an axial direction is smaller than a dimension of the middle portion in an axial direction.

10. The balance disc of claim 9, wherein the weight-reducing portion is provided with a plurality of radial ribs extending radially outward from the intermediate portion, the plurality of radial ribs dividing the weight-reducing portion into a plurality of weight-reducing regions, and oil outlet grooves extending radially are formed in positions on the first end face corresponding to the radial ribs so as to avoid the weight-reducing regions.

11. The balance disc of claim 10, wherein the first end face is provided with a plurality of arc-shaped oil channels, the outer diameter of the middle part is R2, the outer diameter of the arc-shaped oil channels is R4, wherein R2 is equal to or greater than R4+H,

12. The balance disc of claim 11 wherein the radial ribs have a width c and the arcuate oil passages have a width a, wherein c is greater than or equal to a+2h.

13. A drive motor comprising a rotor, a stator and a balancing disk according to any one of claims 1-12.

14. A vehicle comprising the drive motor of claim 13.