Patent Publication Number: US-2022216772-A1

Title: Motor rotor, motor, and vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Chinese Patent Application No. 202011566748.X, filed on Dec. 25, 2020, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     Embodiments of this application relate to the field of drive motor technologies, and in particular, to a motor rotor, a motor, and a vehicle. 
     BACKGROUND 
     A main part of an electric vehicle is an electric drive system, and a power source of the electric drive system is a motor. The motor converts electric energy into mechanical energy, to drive wheels of the electric vehicle to rotate, so as to drive the electric vehicle to travel. In a process in which the motor converts the electric energy into the mechanical energy, a shaft current is generated on a motor rotor. When the shaft current is discharged to a main bearing sleeved on an outer periphery of the motor rotor, the main bearing is electrically corroded. This affects a service life of the main bearing. 
     To resolve the foregoing problem, a conductive bearing and a conductive spring are disposed on a conventional motor rotor. The conductive bearing is disposed in a shaft hole of the motor rotor, and an outer ring of the conductive bearing abuts on an inner wall of the shaft hole. In addition, a conductive spring is pressed against an inner ring of the conductive bearing, and the other end of the conductive spring is grounded. In this way, the shaft current on the motor rotor is transmitted and discharged by using the conductive bearing and the conductive spring, and a strength of currents discharged to the main bearing is reduced, so that the main bearing is prevented from being electrically corroded by the shaft current. 
     However, in a high-speed running process of the motor rotor, because the conductive bearing moves axially and radially with the motor rotor, the conductive spring cannot be in stable contact with the inner ring of the conductive bearing. As a result, the conductive bearing cannot be stably grounded, and consequently the conductive bearing and the main bearing are both electrically corroded by the shaft current. 
     SUMMARY 
     Embodiments of this application provide a motor rotor, a motor, and a vehicle, to resolve a problem that a conductive bearing in a conventional motor rotor and a main bearing are both electrically corroded by a shaft current because the conductive bearing cannot be stably grounded, and another potential problem. 
     An embodiment of this application provides a motor rotor, including a rotor body, a conductive bearing, and a conductive pillar. 
     The rotor body has a shaft hole extending in an axis direction, the conductive bearing is built in the shaft hole, an outer ring of the conductive bearing interference fits with an inner wall of the shaft hole, the conductive pillar internally passes through the conductive bearing, and an inner ring of the conductive bearing interference fits with an outer wall of the conductive pillar. 
     An end of the conductive pillar is grounded. 
     According to the motor rotor provided in this embodiment of this application, the conductive pillar passes through the inner ring of the conductive bearing, the outer wall of the conductive pillar interference fits with the inner ring of the conductive bearing, and an end of the conductive pillar is grounded. In this way, it is ensured that a shaft current on the rotor body is transmitted and discharged by using the conductive bearing and the conductive pillar, to prevent a main bearing of the motor rotor from being electrically corroded by the shaft current. In addition, the conductive bearing is sleeved on the grounded conductive pillar, so that the inner ring of the conductive bearing can interference fit with the outer wall of the conductive pillar, to enable the inner ring of the conductive bearing to be closely attached to the outer wall of the conductive pillar, and avoid the following case: In a high-speed rotation process of the rotor body, the conductive bearing is in unstable contact with the conductive pillar because the rotor body drives the conductive bearing to move axially and radially, and consequently the shaft current cannot be discharged. In addition, the outer ring of the conductive bearing interference fits with an inner ring of the shaft hole. This also further improves closeness of contact between the conductive bearing and the rotor body, and ensures that the shaft current on the rotor body can be stably transmitted to the conductive bearing. In other words, the motor rotor in this embodiment of this application can ensure that the rotor body, the conductive bearing, and the conductive pillar are always electrically connected in a running process of the motor rotor, to ensure that the shaft current on the rotor body is successfully discharged by using the conductive bearing and the conductive pillar. In addition, compared with a conventional technology in which a spring is pressed against the inner ring of the conductive bearing, in this embodiment of this application, the outer wall of the conductive pillar circumferentially abuts on the inner ring of the conductive bearing evenly, so that force is evenly exerted on the conductive bearing, and no offset loading force occurs. Therefore, the conductive bearing is prevented from being damaged due to concentrated stress, and the conductive bearing is prevented from being abnormally worn due to the offset loading force, to prevent conductive grease from overflowing because sealing rings on the conductive bearing are worn, and prolong a service life of the conductive bearing. 
     In an embodiment, the motor rotor further includes a grounding bracket. 
     The grounding bracket is located at an end of the rotor body, one end of the grounding bracket is electrically connected to the conductive pillar, and the other end of the grounding bracket is used to connect to a motor housing of a motor. 
     In actual application, the motor housing may be used as reference ground whose potential is zero, or may be in contact with a chassis of a vehicle to be indirectly connected to ground. In this embodiment of this application, an end of the conductive pillar is electrically connected to the grounding bracket, and the grounding bracket is connected to the motor housing of the motor. In this way, the conductive pillar may be connected to the motor housing by using the grounding bracket. Therefore, it is ensured that the shaft current on the conductive pillar can be discharged to the motor housing by using the grounding bracket or discharged to the ground by using the motor housing, and a grounding process of the conductive pillar is simplified, to improve assembling efficiency of the motor rotor. 
     In an embodiment, the motor rotor further includes an elastic conductive member. 
     An end of the conductive pillar is electrically connected to the grounding bracket by using the elastic conductive member. 
     In this embodiment of this application, the elastic conductive member is disposed between the conductive pillar and the grounding bracket. When an electrical connection between the conductive pillar and the grounding bracket is implemented, because the elastic conductive member has a length used for cushioning, when the rotor body drives the conductive bearing and the conductive pillar to move axially and radially in the high-speed rotation process, the length of the elastic conductive member is adaptively adjusted with movement of the conductive pillar, and the elastic conductive member is not torn. Therefore, it is ensured that the electrical connection between the conductive pillar and the grounding bracket is stable. 
     In an embodiment, the grounding bracket has a positioning hole, and an end of the conductive pillar extends out of the end of the rotor body and internally passes through the positioning hole. 
     The outer wall of the conductive pillar clearance fits with an inner wall of the positioning hole. 
     In this embodiment of this application, the positioning hole is disposed on the grounding bracket, and an end of the conductive pillar internally passes through the positioning hole of the grounding bracket, so that radial movement of the conductive pillar in the rotor body is limited, to improve radial stability of the conductive pillar. In addition, the outer wall of the conductive pillar clearance fits with the inner wall of the positioning hole. Therefore, in the high-speed rotation process, the rotor body can drive the conductive bearing and the conductive pillar to move freely. This effectively prevents a rigid connection between the conductive pillar and the grounding bracket from hampering movement of the inner ring of the conductive bearing, to ensure that a structure of the conductive bearing is not damaged. 
     In an embodiment, a limiting structure is disposed between the conductive pillar and the positioning hole, and the limiting structure is used to limit rotation of the conductive pillar around an axis in the positioning hole, to ensure circumferential stability of the conductive pillar. In this way, stability of contact between the conductive pillar and the inner ring of the conductive bearing is ensured, and stability of the electrical connection between the conductive pillar and the grounding bracket is ensured. 
     In an embodiment, at least a partial outer wall of the conductive pillar that is located inside the positioning hole forms a first plane, and correspondingly, at least a partial inner wall of the positioning hole forms a second plane corresponding to the first plane. 
     The limiting structure includes the first plane and the second plane. 
     In this embodiment of this application, the limiting structure is set as a plane on a partial side wall of the conductive pillar that is located inside the positioning hole, and a plane on at least a partial inner wall of the positioning hole. This effectively prevents the conductive pillar from rotating circumferentially in the positioning hole, and also simplifies the limiting structure. Therefore, manufacturing and assembling efficiency of the entire motor rotor are improved. 
     In an embodiment, the grounding bracket includes a body part and a connection part. 
     The positioning hole is formed on the body part, one end of the connection part is connected to the body part, the other end of the connection part extends in a direction away from an axis of the positioning hole, and the other end of the connection part is used to connect to the motor housing. 
     In this embodiment of this application, the connection part is disposed on the grounding bracket, and the grounding bracket and the motor housing are stably connected to each other by using the connection part. This improves strength of a connection between the grounding bracket and the motor housing. In addition, the positioning hole is disposed on the body part connected to an end of the connection part. Therefore, a limiting effect on the conductive pillar is implemented, and structural strength of the grounding bracket is ensured, so that a service life of the grounding bracket is prolonged. 
     In an embodiment, there are N connection parts, N≥3, and the N connection parts are disposed at intervals around the axis of the positioning hole. 
     In actual application, the motor housing has three mounting holes, and at least three connection parts are disposed on the body part of the grounding bracket. In this way, this improves strength of the connection between the grounding bracket and the motor housing, and fully uses a structure of the motor housing. 
     In an embodiment, an avoidance groove is formed on a side of the connection part that faces the rotor body, and the avoidance groove is used to allow an end of the rotor body to enter. 
     In this embodiment of this application, the avoidance groove is disposed on the connection part. In this way, when the rotor body moves axially in a direction of the connection part in the high-speed running process, the rotor body may enter the avoidance groove without directly colliding with a surface of the connection part, to avoid damage to a structure of the grounding bracket. In addition, disposition of the avoidance groove also prevents the grounding bracket from being interfered by the rotor body in a mounting process. 
     In an embodiment, the motor rotor further includes a bearing housing. 
     The bearing housing is disposed in the shaft hole, the conductive bearing is located in the bearing housing, an outer wall of the bearing housing interference fits with the inner wall of the shaft hole, and the outer ring of the conductive bearing interference fits with an inner wall of the bearing housing. 
     In this embodiment of this application, the bearing housing is disposed in the shaft hole, and the conductive bearing is mounted in the bearing housing. This facilitates assembling of the conductive bearing into the shaft hole of the rotor body, and also improves axial stability of the conductive bearing and the conductive pillar in the shaft hole. In addition, the outer wall of the bearing housing interference fits with the inner wall of the shaft hole, and the outer ring of the conductive bearing interference fits with the inner wall of the bearing housing, so that the bearing housing is in closer contact with each of the rotor body and the conductive bearing. Therefore, it is ensured that the shaft current on the rotor body can be successfully transmitted to the bearing housing and the conductive bearing, and assembling stability of the bearing housing in the shaft hole and assembling stability of the conductive bearing in the bearing housing are also improved. 
     In an embodiment, a cooling path is formed between the outer wall of the bearing housing and the inner wall of the shaft hole, the cooling path extends in the axis direction of the rotor body, and two ends of the cooling path in an extension direction both communicate with the shaft hole of the rotor body. 
     The cooling path is used to allow a cooling medium to flow. 
     In this embodiment of this application, the cooling path is formed between the outer wall of the bearing housing and the inner wall of the shaft hole. In this way, the cooling medium that is introduced into the shaft hole may enter the cooling path, to cool the bearing housing, the conductive bearing, and the conductive pillar. Therefore, the following case is avoided: The conductive bearing is heated and expanded in the high-speed running process of the motor rotor, and consequently a steel ball in the conductive bearing cannot rotate normally and a conductivity of the conductive grease decreases. Therefore, it is ensured that the conductive bearing and the conductive grease are stable. 
     In an embodiment, the bearing housing includes a bearing housing body and a base. 
     An outer wall of the bearing housing body interference fits with the inner wall of the shaft hole, and the bearing housing body includes a first end and a second end that are disposed oppositely to each other in an extension direction. 
     The first end faces the grounding bracket, the first end is opened, and the base is disposed at the second end. 
     In this embodiment of this application, an end of the bearing housing that faces the grounding bracket is opened, to facilitate assembling of the conductive bearing and the conductive pillar. In addition, the base of the bearing housing plays a role of positioning the conductive bearing axially. In other words, provided that the conductive bearing is assembled on the base, positioning of the conductive bearing in the bearing housing can be completed. This improves assembling efficiency of the conductive bearing. 
     In an embodiment, an inner wall of the base is recessed in a direction away from the first end of the bearing housing body to form a limiting groove, and an end of the conductive pillar extends into the limiting groove. 
     A step part is formed on a side wall of the conductive pillar, and the step part is located between the grounding bracket of the motor rotor and the base. 
     A distance between the step part and the grounding bracket is a first distance, a distance between an outer peripheral surface of the limiting groove and an end of the conductive pillar that faces the base is a second distance, and the first distance is less than the second distance. In this way, when one end of the conductive pillar moves axially to the grounding bracket in the high-speed running process of the rotor body, the other end of the conductive pillar is still located in the limiting groove and is not separated from the limiting groove. This reduces a distance by which the conductive pillar moves axially, and ensures axial stability of the conductive pillar. 
     In an embodiment, a stop part extends from on the outer wall of the conductive pillar in a direction away from the axis. 
     The conductive bearing is located between the stop part and the base, and a distance between an end of the stop part and the inner wall of the bearing housing is less than a diameter of the steel ball in the conductive bearing, to ensure that the steel ball in the conductive bearing does not drop between the stop part and the inner wall of the bearing housing, and ensure that the steel ball does not drop from the first end of the bearing housing to the outside of the rotor body. 
     In an embodiment, a boss is formed on the inner wall of the shaft hole, and an end of the bearing housing that is away from the grounding bracket abuts on the boss, to further limit axial movement of the bearing housing in the rotor body. In addition, the boss plays a role in quickly positioning assembling of the bearing housing in the shaft hole, namely, provided that the bearing housing is placed downwards to abut on the boss, positioning of the bearing housing in the shaft hole is completed. 
     An embodiment of this application further provides a motor, including a motor housing, a main bearing, and the foregoing motor rotor. The motor housing is sleeved on an outer wall of the motor rotor by using the main bearing. 
     In this embodiment of this application, the foregoing motor rotor is disposed in the motor, to prevent the main bearing of the motor from being electrically corroded by a shaft current. In addition, because no concentrated stress occurs in a conductive bearing of the motor rotor, and the conductive bearing is not subject to offset loading force, the conductive bearing is prevented from being abnormally worn. Therefore, conductive grease is prevented from overflowing because sealing rings on the conductive bearing are worn, a service life of the conductive bearing is prolonged, it is ensured that the shaft current on the motor rotor is discharged by using the conductive bearing, and the main bearing is not electrically corroded, to ensure that the motor runs normally. 
     An embodiment of this application further provides a vehicle, including wheels and the foregoing motor. A motor rotor of the motor is connected to the wheels to drive the wheels to rotate. 
     In this embodiment of this application, the foregoing motor is mounted on the vehicle, so that it is ensured that the motor of the vehicle can work stably, to stably drive the wheels. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a structure of a motor according to an embodiment of this application; 
         FIG. 2  is a partially enlarged view of I in  FIG. 1 ; 
         FIG. 3  is a schematic diagram of a structure of a part in  FIG. 2 ; 
         FIG. 4  is a schematic diagram of a structure of a conductive pillar in  FIG. 3 ; 
         FIG. 5  is a top view of  FIG. 4 ; 
         FIG. 6  is a schematic diagram of a structure of a grounding bracket in  FIG. 3 ; 
         FIG. 7  is a top view of  FIG. 6 ; 
         FIG. 8  is a schematic diagram of a structure of a bearing housing in  FIG. 3 ; and 
         FIG. 9  is a sectional view of  FIG. 8 . 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS 
       100 : motor rotor;  200 : motor housing;  300 : main bearing;  110 : rotor body;  120 : conductive bearing;  130 : conductive pillar;  140 : bearing housing;  150 : grounding bracket;  160 : elastic conductive member;  170 : first fastener;  180 : second fastener;  190 : motor shaft;  111 : shaft hole;  112 : boss;  113 : cooling path;  121 : outer ring;  122 : steel ball;  123 : inner ring;  131 : first plane;  132 : stop part;  133 : step part;  141 : mounting cavity;  142 : bearing housing body;  143 : base;  144 : groove;  151 : positioning hole;  152 : body part;  153 : connection part;  1431 : limiting groove;  1511 : second plane;  1531 : avoidance groove;  1532 : second mounting hole;  1533 : third mounting hole. 
     DESCRIPTION OF EMBODIMENTS 
     Terms used in embodiments of this application are merely used to explain specific embodiments of this application, but are not intended to limit this application. 
       FIG. 1  is a schematic diagram of a structure of a motor according to an embodiment of this application, and  FIG. 2  is a partially enlarged view of I in  FIG. 1 . Refer to  FIG. 1  and  FIG. 2 . In a conventional technology, the motor includes a motor rotor  100  and a stator, the stator is movably sleeved on an outer periphery of the motor rotor  100 , and the motor rotor  100  is connected to loads such as wheels. The motor rotor  100  includes a motor shaft  190 , an iron core and an excitation winding that are sleeved on the motor shaft, and the like. The motor shaft  190  of the motor rotor  100  is connected to loads such as wheels, to drive, when the motor shaft  190  rotates, the wheels to rotate. 
     During working, the stator generates a rotating magnetic field in an air gap between the stator and the motor rotor  100 . When a direct current is applied to the excitation winding of the motor rotor  100 , a static magnetic field with constant polarity is generated. Under an action of armature reaction, the motor rotor  100  generates a torque relative to the stator, so that the motor shaft  190  drives loads such as wheels to move. 
     In actual application, the stator of the motor includes at least a motor housing  200 . In this embodiment of this application, the motor housing  200  of the motor is mainly used as the stator of the motor. The following describes a structure of the motor by using the motor housing  200  as the stator. 
     In an embodiment, the motor housing  200  and the motor rotor  100  are movably connected to each other by using a main bearing  300 . For example, an outer ring of the main bearing  300  interference fits with an inner wall of the motor housing  200 , and an inner ring of the main bearing  300  interference fits with an outer wall of the motor rotor  100  such as the motor shaft  190 . Therefore, in a high-speed running process of the motor rotor  100 , the motor housing  200  can maintain static under an action of the main bearing  300 , to ensure that the motor rotor  100  rotates stably around an axis l in the motor housing  200 . 
     It should be noted that, as shown in  FIG. 1 , the axis l may be an axis of the motor rotor  100 . 
     Refer to  FIG. 2 . When a PWM inverter supplies power to the excitation winding of the motor rotor  100 , a high-frequency common-mode voltage is generated. The high-frequency common-mode voltage is coupled to the motor rotor  100  by using parasitic capacitance of the motor, to form a shaft voltage. When the shaft voltage exceeds a breakdown voltage threshold of an oil film on the motor rotor  100 , a shaft current is formed on the motor rotor  100 . When the shaft current is discharged to the main bearing  300  on the outer periphery of the motor rotor  100 , partial discharging is performed between a steel ball and a race of the main bearing  300 , and an electric fusion pit is formed on the race. Consequently, the main bearing  300  is electrically corroded, and a service life of the main bearing  300  is affected. 
     To prevent the main bearing  300  from being electrically corroded by the shaft current, a conductive bearing  120  and a conductive spring (not shown in the figure) are disposed on the conventional motor rotor  100 . The conductive bearing  120  is disposed in a shaft hole  111  of the motor rotor  100 , and the conductive bearing  120  is close to an end of the motor rotor  100 . An outer ring  121  of the conductive bearing  120  abuts on an inner wall of the shaft hole  111 . In addition, a conductive spring is pressed against an inner ring  123  of the conductive bearing  120 , and the other end of the conductive spring is grounded. For example, the other end of the conductive spring may be connected to ground or reference ground (for example, the motor housing  200 ). In this way, a resistance of a conductive loop formed from the motor rotor  100 , the conductive bearing  120 , and the conductive spring to the ground (or the reference ground) is less than a resistance of a conductive loop formed between the motor rotor  100  and the main bearing  300 . Therefore, the shaft current on the motor rotor  100  is mostly transmitted and discharged by using the conductive bearing  120  and the conductive spring, and strength of a current discharged to the main bearing  300  is reduced, so that the main bearing  300  is prevented from being electrically corroded by the shaft current. 
     In actual application, a difference between the conductive bearing  120  and the main bearing  300  lies in that the conductive bearing  120  further includes two sealing rings (not shown in the figure) disposed oppositely to each other between the outer ring  121  and the inner ring  123 . There is a gap between the outer ring  121  and the inner ring  123 , and the two sealing rings each are disposed between two ends of the outer ring  121  and the inner ring  123  in an axis direction (namely, a thickness direction), namely, the two sealing rings each are disposed in gaps on two sides of the conductive bearing  120  in the axis direction (namely, the thickness direction). A steel ball  122  in the conductive bearing  120  is sealed between the two sealing rings, and conductive grease (not shown in the figure) is filled in a gap between the steel ball  122  and each of the outer ring  121  and the inner ring  123 . The shaft current discharged from the motor rotor  100  to the outer ring  121  of the conductive bearing  120  may be transmitted quickly to the inner ring  123  by using the conductive grease and the steel ball  122 , so that a conductive property of the conductive bearing  120  is improved. 
     Under an action of elastic force, a tongue of the conductive spring is pressed against a surface that is of the inner ring  123  of the conductive bearing  120  and that faces away from the outer ring  121 . In this way, the current on the motor rotor  100  is transmitted to the conductive spring sequentially by using the outer ring  121 , the conductive grease, the steel ball  122 , and the inner ring  123  of the conductive bearing  120 , and is finally discharged to the ground or the reference ground by using the conductive spring. 
     However, a surface of the inner ring  123  of the conductive bearing  120  is a curved surface, and a surface of the tongue of the conductive spring is a flat surface. When the tongue of the conductive spring is pressed against the inner ring  123  of the conductive bearing  120 , two ends of the tongue only in a width direction are in contact with the surface of the inner ring  123 , namely, the conductive spring is in linear contact with the inner ring  123  of the conductive bearing  120 . In this case, in the high-speed running process of the motor rotor  100 , the conductive bearing  120  moves axially and radially with the motor rotor  100 , and the conductive spring cannot be in stable contact with the inner ring  123  of the conductive bearing  120 . Consequently, the conductive bearing  120  cannot be stably grounded, and both the conductive bearing  120  and the main bearing  300  are electrically corroded by the shaft current. 
     In addition, because a point at which the conductive spring is pressed against the conductive bearing  120  is not in a diameter direction of the steel ball  122 , namely, force exerted between the conductive spring and the conductive bearing  120  deviates from the diameter direction of the steel ball  122 , the conductive bearing  120  is subject to offset loading force. The offset loading force causes the inner ring  123  of the conductive bearing  120  to be skewed, and consequently the gap between the inner ring  123  and the outer ring  121  is not equal at all circumferential positions. As a result, the inner ring  123 , the steel ball  122 , the outer ring  121 , and the like of the conductive bearing  120  are abnormally worn, and the two sealing rings on the conductive bearing  120  in the thickness direction are also worn due to uneven force. Consequently, the conductive grease in the conductive bearing  120  overflows from the two sides of the conductive bearing  120  to affect a service life and the conductive property of the conductive bearing  120 . 
     The embodiments of this application provide a motor rotor, a motor, and a vehicle. A conductive pillar passes through an inner ring of a conductive bearing, an outer wall of the conductive pillar interference fits with the inner ring of the conductive bearing, and an end of the conductive pillar is grounded. In this way, it is ensured that a shaft current on a rotor body is transmitted and discharged by using the conductive bearing and the conductive pillar, to prevent a main bearing of the motor from being electrically corroded by the shaft current. In addition, the conductive bearing is sleeved on the grounded conductive pillar, so that the inner ring of the conductive bearing can interference fit with the outer wall of the conductive pillar, to enable the inner ring of the conductive bearing to be closely attached to the outer wall of the conductive pillar, and avoid the following case: In a high-speed rotation process of the rotor body, the conductive bearing is in unstable contact with the conductive pillar because the rotor body drives the conductive bearing to move axially and radially, and consequently the shaft current cannot be discharged. In addition, an outer ring of the conductive bearing interference fits with an inner ring of a shaft hole. This also further improves closeness of contact between the conductive bearing and the rotor body, and ensures that the shaft current on the rotor body can be stably transmitted to the conductive bearing. In other words, the motor rotor in the embodiments of this application can ensure that the rotor body, the conductive bearing, and the conductive pillar are always electrically connected in a running process of the motor rotor, to ensure that the shaft current on the rotor body is transmitted and discharged by using the conductive bearing and the conductive pillar. In addition, compared with the conventional technology in which the spring is pressed against the inner ring of the conductive bearing, in the embodiments of this application, the outer wall of the conductive pillar circumferentially abuts on the inner ring of the conductive bearing evenly, so that force is evenly exerted on the conductive bearing, and no offset loading force occurs. Therefore, the conductive bearing is prevented from being damaged due to concentrated stress, and the conductive bearing is prevented from being abnormally worn due to the offset loading force, to prevent the conductive grease from overflowing because the sealing rings on the conductive bearing are worn, and prolong the service life of the conductive bearing. 
     The following describes in detail specific structures of the motor rotor, the motor, and the vehicle that are provided in the embodiments of this application. 
       FIG. 3  is a schematic diagram of a structure of a part in  FIG. 2 . Refer to  FIG. 1  to  FIG. 3 . A motor rotor  100  in an embodiment of this application includes a rotor body  110 , a conductive bearing  120 , and a conductive pillar  130 . 
     Refer to  FIG. 1 . In actual application, the rotor body  110  includes a motor shaft  190 , an iron core and an excitation winding that are sleeved on the motor shaft  190 , and the like. A component such as the iron core and the excitation winding is sleeved on a partial outer wall of the motor shaft  190 . For example, two ends of the motor shaft  190  in an axis direction extend out of two end faces of the iron core. In this way, the component such as the iron core and the excitation winding does not exist on partial outer walls of the motor shaft  190  that are close to the two ends. 
     Refer to  FIG. 1  and  FIG. 2 . The rotor body  110  in this embodiment of this application has shaft hole  111  extending in an axis direction. The shaft hole  111  is disposed on an axis l of the rotor body  110 , and two ends of the shaft hole  111  penetrate through two end faces of the rotor body  110  in the axis direction. For example, the shaft hole  111  is disposed in the motor shaft  190  of the rotor body  110 , and the shaft hole  111  extends to two end faces of the motor shaft  190  along the axis l of the motor shaft  190 . The conductive bearing  120  is built in the shaft hole  111 . 
     For ease of description, two ends of the rotor body  110  that are disposed oppositely to each other in an extension direction may be respectively used as a first end of the rotor body  110  and a second end of the rotor body  110 . 
     It may be understood that there may be one or two conductive bearings  120  in this embodiment of this application. When there is one conductive bearing  120 , the conductive bearing  120  may be built in the shaft hole  111 , and the conductive bearing  120  is close to one of the ports of the rotor body  110 . For example, the conductive bearing  120  is close to the first end of the rotor body  110 , namely, the conductive bearing  120  is located in a part of the motor shaft  190  that extends out of the iron core. 
     When there are two conductive bearings  120 , the two conductive bearings  120  are respectively built in the rotor body  110 , and are close to the two ports of the rotor body  110 . For example, one of the conductive bearings  120  is close to the first end of the rotor body  110 , and the other conductive bearing  120  is close to the second end of the rotor body  110 , namely, the two conductive bearings  120  are respectively built in two ends of the motor shaft  190  that extend into the iron core. 
     In this embodiment of this application, a quantity of conductive bearings  120  is not limiting, and may be adjusted based on an actual requirement. 
     Refer to  FIG. 3 . In actual application, the conductive bearing  120  includes an inner ring  123 , a steel ball  122 , an outer ring  121 , two sealing rings (not shown in the figure), and conductive grease (not shown in the figure). The outer ring  121  is sleeved on an outer periphery of the inner ring  123 , the steel ball  122  and the conductive grease are located in a gap (which may also be referred to as a race) between the outer ring  121  and the inner ring  123 , and the two sealing rings each are disposed between two ends of the outer ring  121  and the inner ring  123  in an axis direction (namely, a thickness direction), so that the steel ball  122  and the conductive grease of the conductive bearing  120  are sealed between the two sealing rings. A shaft current discharged from the motor rotor  100  to the outer ring  121  of the conductive bearing  120  may be quickly transmitted to the inner ring  123  by using the conductive grease and the steel ball  122 , to improve a conductive property of the conductive bearing  120 . 
     For a specific structure of the conductive bearing  120 , refer to a conventional technology directly. Details are not described herein again. 
     Still refer to  FIG. 3 . The outer ring  121  of the conductive bearing  120  interference fits with an inner wall of the shaft hole  111 , the conductive pillar  130  internally passes through the conductive bearing  120 , and the inner ring  123  of the conductive bearing  120  interference fits with an outer wall of the conductive pillar  130 . The inner wall of the shaft hole  111  may be understood as an inner wall of the rotor body  110 . 
     It may be understood that, in an embodiment, the outer ring  121  of the conductive bearing  120  directly interference fits with the inner wall of the shaft hole  111 , namely, the outer ring  121  of the conductive bearing  120  is in direct contact with the inner wall of the shaft hole  111 . 
     In another embodiment, the outer ring  121  of the conductive bearing  120  indirectly interference fits with the inner wall of the shaft hole  111 , namely, the outer ring  121  of the conductive bearing  120  is in indirect contact with the inner wall of the shaft hole  111  (as shown in  FIG. 3 , for details, refer to a manner that is mentioned below and in which interference fitting between the outer ring  121  of the conductive bearing  120  and the inner wall of the shaft hole  111  is implemented by using a side wall of a bearing housing  140 ). 
     The following first describes a structure in which the outer ring  121  of the conductive bearing  120  directly interference fits with the inner wall of the shaft hole  111 . 
     The rotor body  110  in this embodiment of this application and the outer ring  121  of the conductive bearing  120  are static relative to each other. For example, in a process in which the rotor body  110  rotates around the axis at a high speed, the outer ring  121  of the conductive bearing  120  rotates synchronously with the rotor body  110 . In addition, the inner ring  123  of the conductive bearing  120  and the conductive pillar  130  are static relative to each other. 
       FIG. 4  is a schematic diagram of a structure of a conductive pillar in  FIG. 3 , and  FIG. 5  is a top view of  FIG. 4 . Refer to  FIG. 3  to  FIG. 5 . The conductive pillar  130  is columnar, and the conductive pillar  130  is conductive. For example, the conductive pillar  130  may be made of conductive metal such as iron, copper, or steel. In addition, the conductive pillar  130  may be of a hollow structure, for example, a through hole is disposed on an axis of the conductive pillar  130 , to reduce a weight of the conductive pillar  130 , and facilitate mounting and removal of the conductive pillar  130 . 
     It may be understood that, after the conductive pillar  130  is assembled on the rotor body  110 , the axis of the conductive pillar  130  overlaps the axis l of the rotor body  110 . 
     An end of the conductive pillar  130  in this embodiment of this application is grounded. It should be noted that “being grounded” herein may be connected to reference ground or ground. 
     For example, an end of the conductive pillar  130  penetrates through one of the ports of the rotor body  110 , and is connected to a motor housing  200  of the motor by using a conductive member such as a conductor. In actual application, when the motor in this embodiment of this application is applied to a vehicle, the motor housing  200  of the motor is in contact with a chassis of the vehicle, and the vehicle is on a road, the chassis of the vehicle is in contact with the ground. In this case, an end of the conductive pillar  130  is connected to the motor housing  200  by using a conductive member such as a conductor, so that the conductive pillar  130  is grounded. 
     When the motor housing  200  is not in contact with the chassis of the vehicle, namely, when the motor housing  200  and the chassis of the vehicle are spaced apart, because the motor housing  200  is not live, the motor housing  200  may be used as the reference ground. In this way, an end of the conductive pillar  130  is connected to the motor housing  200  of the motor by using a conductive member such as a conductor, to ensure that the conductive pillar  130  accesses the reference ground whose potential is zero. 
     When a shaft current is generated on the motor rotor  100 , the shaft current is first discharged to the outer ring  121  of the conductive bearing  120  by using the rotor body  110 , then flows to the conductive pillar  130  sequentially by using the steel ball  122 , the conductive grease, and the inner ring  123  of the conductive bearing  120 , and is finally discharged by using the conductive pillar  130 . Because the conductive pillar  130  is grounded, a resistance of a conductive loop formed from the rotor body  110 , the conductive bearing  120 , and the conductive pillar  130  to the ground (or the reference ground) is less than a resistance of a conductive loop formed between the rotor body  110  and a main bearing  300 . Therefore, the current on the rotor body  110  is mostly transmitted and discharged by using the conductive bearing  120  and the conductive pillar  130 , and strength of a current flowing to the main bearing  300  is reduced, so that the main bearing  300  of the motor  100  is prevented from being electrically corroded by the shaft current. 
     In this embodiment of this application, the conductive bearing  120  is sleeved on the grounded conductive pillar  130 , so that the inner ring  123  of the conductive bearing  120  can interference fit with the outer wall of the conductive pillar  130 , to enable the inner ring  123  of the conductive bearing  120  to be closely attached to the outer wall of the conductive pillar  130 , and avoid the following case: In the high-speed rotation process of the rotor body  110 , the conductive bearing  120  is in unstable contact with the conductive pillar  130  because the rotor body  110  drives the conductive bearing  120  to move axially and radially, and consequently the shaft current cannot be discharged. 
     In addition, the outer ring  121  of the conductive bearing  120  interference fits with the inner wall of the shaft hole  111 . This also further improves closeness of contact between the conductive bearing  120  and the rotor body  110 , and ensures that the shaft current on the rotor body  110  can be stably transmitted to the conductive bearing  120 . In other words, the motor rotor  100  in this embodiment of this application can ensure that the rotor body  110 , the conductive bearing  120 , and the conductive pillar  130  are always electrically connected in a running process of the motor rotor  100 , to ensure that the shaft current on the rotor body  110  is successfully discharged by using the conductive bearing  120  and the conductive pillar  130 . 
     In addition, compared with the conventional technology in which the conductive spring is pressed against the inner ring  123  of the conductive bearing  120 , in this embodiment of this application, the outer wall of the conductive pillar  130  circumferentially abuts on the inner ring  123  of the conductive bearing  120  evenly, so that force is evenly exerted on the conductive bearing  120 , and no offset loading force occurs. Therefore, the conductive bearing  120  is prevented from being damaged due to concentrated stress, and the conductive bearing  120  is prevented from being abnormally worn due to the offset loading force, to prevent the conductive grease from overflowing because the sealing rings on the conductive bearing  120  are worn, and prolong a service life of the conductive bearing  120 . 
       FIG. 6  is a schematic diagram of a structure of a grounding bracket in  FIG. 3 . Refer to  FIG. 3  and  FIG. 6 . To facilitate grounding of an end of the conductive pillar  130 , the motor rotor  100  in this embodiment of this application may further include a grounding bracket  150 . The grounding bracket  150  is located at an end of the rotor body  110 , one end of the grounding bracket  150  is electrically connected to the conductive pillar  130 , and the other end of the grounding bracket  150  is connected to the motor housing  200  of the motor. 
     The grounding bracket  150  in this embodiment of this application is close to an end of the rotor body  110  that is provided with the conductive bearing  120 , and the grounding bracket  150  is located outside the rotor body  110 . For example, when the conductive bearing  120  is adjacent to the first end of the rotor body  110 , the grounding bracket  150  is located outside the first end of the rotor body  110 . Correspondingly, when the conductive bearing  120  is adjacent to the second end of the rotor body  110 , the grounding bracket  150  is located outside the second end of the rotor body  110 . 
     During specific disposition, one end of the conductive pillar  130  extends into the shaft hole  111  of the rotor body  110  and fits with the conductive bearing  120 , and the other end of the conductive pillar  130  may extend out of the end of the rotor body  110  and is electrically connected to the grounding bracket  150 . For example, when the conductive bearing  120  is adjacent to the first end of the rotor body  110 , an end of the conductive pillar  130  extends out of the first end of the rotor body  110  and is electrically connected to the grounding bracket  150  outside the first end of the rotor body  110 . 
     It may be learned from the foregoing that, when the motor in this embodiment of this application is applied to a vehicle such as an electric vehicle, and the motor housing  200  of the motor is always connected to a chassis of the vehicle, if an end of the conductive pillar  130  is electrically connected to the grounding bracket  150 , and the grounding bracket  150  is connected to the motor housing  200  of the motor, the conductive pillar  130  may be electrically connected to the ground by using the grounding bracket  150  and the motor housing  200 . When the motor housing  200  and the chassis of the vehicle are spaced apart, the motor housing  200  may be directly used as the reference ground whose potential is zero. In this way, the conductive pillar  130  may be electrically connected, by using the grounding bracket  150 , to the reference ground whose potential is zero. Therefore, it is ensured that the shaft current on the conductive pillar  130  can be discharged by using the grounding bracket  150  and the motor housing  200 , and a grounding process of the conductive pillar  130  is simplified, to improve assembling efficiency of the motor rotor  100 . 
     The conductive pillar  130  and the grounding bracket  150  may be electrically connected to each other by using a conductive member. The conductive member may be a conductor. 
     Refer to  FIG. 3 . In some examples, the motor rotor  100  may further include an elastic conductive member  160 . The elastic conductive member  160  may be used as a conductive member. One end of the elastic conductive member  160  is electrically connected to the conductive pillar  130 , and the other end of the elastic conductive member  160  is electrically connected to the grounding bracket  150 . 
     During specific connection, one end of the elastic conductive member  160  may be fastened to the conductive pillar  130  through bonding, clamping, screw connection, or the like, and the other end of the elastic conductive member  160  may also be fastened to the grounding bracket  150  through bonding, clamping, screw connection, or the like. 
     It should be noted that, when the elastic conductive member  160  is bonded to the conductive pillar  130 , adhesive used to bond the elastic conductive member  160  to the conductive pillar  130  needs to be conductive adhesive, to ensure that a current path is formed between the conductive pillar  130  and the elastic conductive member  160 . For example, a composition material of the conductive adhesive may include but is not limited to one or more of an epoxy resin, an acrylic resin, and polyurethane. 
     An example in which the elastic conductive member  160  is electrically connected to the grounding bracket  150  is used. Refer to  FIG. 3  and  FIG. 6 . A first mounting hole (not shown in the figure) may be disposed on the elastic conductive member  160 , a second mounting hole  1532  that matches the first mounting hole is disposed on the grounding bracket  150 , and the elastic conductive member  160  is fastened to the grounding bracket  150  by using a first fastener  170  that passes through the first mounting hole and the second mounting hole  1532 . It may be understood that the first fastener  170  is a conductive connector. For example, the fastener may be a screw, a rivet, or a bolt, to implement an electrical connection between the elastic conductive member  160  and the grounding bracket  150 . 
     The elastic conductive member  160  may include but is not limited to any one of a rubber member and a silicone member. For example, the elastic conductive member  160  may be another elastic conductive member such as a metal spring. 
     In addition, the grounding bracket  150  may also be fastened to the motor housing  200  through bonding, clamping, screw connection, or the like. For example, as shown in  FIG. 3  and  FIG. 6 , a third mounting hole  1533  may be disposed on the grounding bracket  150 . Correspondingly, a fourth mounting hole (not shown in the figure) that matches the third mounting hole  1533  is disposed on the motor housing  200 . The grounding bracket  150  is fastened to the motor housing  200  by using a second fastener  180  that passes through the third mounting hole  1533  and the fourth mounting hole. In this way, stability of a connection between the grounding bracket  150  and the motor housing  200  is ensured, and an assembling structure between the grounding bracket  150  and the motor housing  200  is simplified, to improve assembling efficiency of the motor. 
     The second fastener  180  may include but is not limited to a conductive fastener such as a bolt, a screw, or a rivet. 
     It should be noted that, when the grounding bracket  150  is bonded to the motor housing  200 , adhesive used to bond the grounding bracket  150  to the motor housing  200  needs to be conductive adhesive, to ensure that a current path is formed between the grounding bracket  150  and the motor housing  200 . 
     In this embodiment of this application, the elastic conductive member  160  is disposed between the conductive pillar  130  and the grounding bracket  150 . When an electrical connection between the conductive pillar  130  and the grounding bracket  150  is implemented, because the elastic conductive member  160  has a length used for cushioning, when the rotor body  110  drives the conductive bearing  120  and the conductive pillar  130  to move axially and radially in the high-speed rotation process, the length of the elastic conductive member  160  is adaptively adjusted with movement of the conductive pillar  130 , and the elastic conductive member  160  is not torn. Therefore, it is ensured that the electrical connection between the conductive pillar  130  and the grounding bracket  150  is stable. 
     Still refer to  FIG. 3  and  FIG. 6 . The grounding bracket  150  in this embodiment of this application has a positioning hole  151 . An end of the conductive pillar  130  may extend out of the end of the rotor body  110  and pass through the positioning hole  151 , so that radial movement of the conductive pillar  130  in the rotor body  110  is limited, to improve radial stability of the conductive pillar  130 . It should be noted that a radial direction of the rotor body  110  is consistent with a radial direction of the conductive pillar  130 . In this case, when the conductive pillar  130  internally passes through the positioning hole  151  of the grounding bracket  150 , radial movement of the conductive pillar  130  relative to the conductive pillar  130  is also correspondingly limited, to prevent the conductive pillar  130  from shaking from side to side or deviating. 
     The outer wall of the conductive pillar  130  may clearance fit with an inner wall of the positioning hole  151 . Therefore, in the high-speed rotation process, the rotor body  110  can drive the conductive bearing  120  and the conductive pillar  130  to move freely. This effectively prevents a rigid connection between the conductive pillar  130  and the grounding bracket  150  from hampering movement of the inner ring  123  of the conductive bearing  120 , to ensure that a structure of the conductive bearing  120  is not damaged. 
     To further improve stability of the conductive pillar  130 , a limiting structure may be further disposed between the conductive pillar  130  and the positioning hole  151  in this embodiment of this application. The limiting structure is used to limit rotation of the conductive pillar  130  around the axis in the positioning hole  151 , to ensure circumferential stability of the conductive pillar  130 . In this way, stability of contact between the conductive pillar  130  and the inner ring  123  of the conductive bearing  120  is ensured, and stability of the electrical connection between the conductive pillar  130  and the grounding bracket  150  is ensured, to avoid the following case: When the conductive pillar  130  rotates around the axis of the conductive pillar  130 , an end of a conductive member such as the elastic conductive member  160  or a conductor is separated from the conductive pillar  130 . 
     In an embodiment, a positioning protrusion (not shown in the figure) may be disposed on a side wall of the conductive pillar  130 . Correspondingly, a positioning groove (not shown in the figure) that matches the positioning protrusion is disposed on the inner wall of the positioning hole  151 . After an end of the conductive pillar  130  internally passes through the positioning hole  151 , the positioning protrusion extends into the positioning groove. In this example, the positioning protrusion and the positioning groove are used as the limiting structure to limit rotation of the conductive pillar  130  around the axis of the conductive pillar  130  in the positioning hole  151 . 
       FIG. 7  is a top view of  FIG. 6 . Refer to  FIG. 3 ,  FIG. 4 , and  FIG. 7 . In another embodiment, at least a partial outer wall of the conductive pillar  130  that is located inside the positioning hole  151  forms a first plane  131  (as shown in  FIG. 4 ), and correspondingly, at least a partial inner wall of the positioning hole  151  forms a second plane  1511  (as shown in  FIG. 7 ) corresponding to the first plane  131 . The limiting structure includes the first plane  131  and the second plane  1511 . 
     In this embodiment of this application, the limiting structure is set as a plane on a partial side wall of the conductive pillar  130  that is located inside the positioning hole  151 , and a plane on at least a partial inner wall of the positioning hole  151 . This effectively prevents the conductive pillar  130  from rotating around the axis l in the positioning hole  151 , and also simplifies the limiting structure. Therefore, manufacturing and assembling efficiency of the entire motor rotor  100  are improved. 
     Refer to  FIG. 5 . A plurality of first planes  131  may be formed on the side wall of the conductive pillar  130 , and the plurality of first planes  131  are disposed at intervals around the axis of the conductive pillar  130 . Correspondingly, as shown in  FIG. 7 , a plurality of second planes  1511  are formed on the inner wall of the positioning hole  151 , the plurality of second planes  1511  are disposed at intervals around an axis of the positioning hole  151 , and the plurality of first planes  131  are respectively opposite to the corresponding second planes  1511 , to ensure that the conductive pillar  130  does not rotate in the positioning hole  151 . 
     For example, as shown in  FIG. 5 , two first planes  131  may be formed on the side wall of the conductive pillar  130 , and the two first planes  131  are disposed oppositely to each other on two sides of the axis of the conductive pillar  130 . Correspondingly, as shown in  FIG. 7 , two second planes  1511  are formed on the inner wall of the positioning hole  151 , and the two second planes  1511  are disposed oppositely to each other on two sides of the axis of the positioning hole  151 . An end of the conductive pillar  130  penetrates into the positioning hole  151  of the grounding bracket  150 , and one first plane  131  of the conductive pillar  130  fits with one second plane  1511  of the grounding bracket  150 , and the other first plane  131  of the conductive pillar  130  fits with the other second plane  1511  of the grounding bracket  150 . This further improves a limiting effect of the limiting structure on rotation of the conductive pillar  130 , and ensures that the conductive pillar  130  does not rotate around the axis during high-speed rotation of the rotor body  110 , namely, ensures that the conductive pillar  130  is static in the running process of the motor rotor  100 . Therefore, stability of the electrical connection between the conductive pillar  130  and each of the conductive bearing  120  and the grounding bracket  150  is further improved. 
     Refer to  FIG. 6  and  FIG. 7 . During specific disposition, the grounding bracket  150  may include a body part  152  and a connection part  153 , the positioning hole  151  is formed on the body part  152 , and an end of the conductive pillar  130  penetrates into the positioning hole  151  on the body part  152 , to limit radial movement of the conductive pillar  130  in the rotor body  110 . One end of the connection part  153  is connected to the body part  152 , and the other end of the connection part  153  is connected to the motor housing  200 . 
     There may be one or more connection parts  153 , and the plurality of connection parts  153  are disposed at intervals around an outer periphery of the positioning hole  151 . For example, there are N connection parts  153 , and N≥3, namely, there may be at least three connection parts  153 . The at least three connection parts  153  are disposed at intervals around the outer periphery of the positioning hole  151 , one end of each connection part  153  is connected to the body part  152 , the other end of each connection part  153  extends in a direction away from the axis of the positioning hole  151 , and the other end of each connection part  153  is used to connect to the motor housing  200 . 
     An example in which there are three connection parts  153  is used. The three connection parts  153  may be distributed at intervals on an outer periphery of the body part  152  around the axis of the positioning hole  151 , so that lines between points at which the grounding bracket  150  is connected to the motor housing  200  form a triangle, to improve stability of the connection between the grounding bracket  150  and the motor housing  200 . 
     The three connection parts  153  may be evenly distributed on the outer periphery of the body part  152 , namely, an angle between two adjacent connection parts  153  is 120°, to facilitate manufacturing of the grounding bracket  150 . 
     In actual application, the motor housing  200  has three mounting holes. In this way, three connection parts  153  are disposed on an end of the body part  152 . This improves strength of the connection between the grounding bracket  150  and the motor housing  200 , and fully uses a structure of the motor housing  200 . 
     In this embodiment of this application, the grounding bracket  150  is set as the body part  152  and the connection part  153  connected to an end of the body part  152 , and the grounding bracket  150  and the motor housing  200  are stably connected to each other by using the connection part  153 . This improves strength of the connection between the grounding bracket  150  and the motor housing  200 . In addition, the positioning hole  151  is disposed on the body part  152  connected to an end of the connection part  153 . Therefore, a limiting effect on the conductive pillar  130  is implemented, and structural strength of the grounding bracket  150  is ensured, so that a service life of the grounding bracket  150  is prolonged. 
     In some examples, the third mounting hole  1533  may be disposed at an end of each connection part  153 . Correspondingly, three fourth mounting holes respectively corresponding to the third mounting holes  1533  are disposed on the motor housing  200 . In this way, the second fastener  180  may pass through each pair of third mounting hole  1533  and fourth mounting hole that is coaxial with the third mounting hole  1533 , to further improve strength of the connection between the grounding bracket  150  and the motor housing  200 . 
     In addition, an end of the elastic conductive member  160  may be connected to any connection part  153 , to improve assembling flexibility of the elastic conductive member  160 . For example, the second mounting hole  1532  may be disposed on each of the three connection parts  153  of the grounding bracket  150 , and the first mounting hole on the elastic conductive member  160  may fit with any second mounting hole  1532 . In this way, the first fastener  170  passes through the first mounting hole of the elastic conductive member  160  and the second mounting hole  1532 , to fasten an end of the elastic conductive member  160  to the connection part  153 . 
     It should be noted that the grounding bracket  150  may be an integrally formed member, namely, the main part  152  and the at least three connection parts  153  are integrally injection molded, to improve structural strength of the grounding bracket  150  and simplify an assembling process of the grounding bracket  150 . 
     In actual application, in the high-speed running process, the rotor body  110  is prone to move axially. When an end of the rotor body  110  moves in a direction close to the grounding bracket  150 , the rotor body  110  inevitably collides with the connection part  153  of the grounding bracket  150  repeatedly, to cause damage to a structure of the grounding bracket  150 . Based on this, as shown in  FIG. 6  and  FIG. 7 , an avoidance groove  1531  may be formed on a side of each connection part  153  that faces the rotor body  110 , and the avoidance groove  1531  is used to allow an end of the rotor body  110  to enter. In this way, when the rotor body  110  moves axially in a direction of the connection part  153  in the high-speed running process, the rotor body  110  may enter the avoidance groove  1531  without directly colliding with a surface of the connection part  153 , to avoid damage to the structure of the grounding bracket  150 . 
     In addition, disposition of the avoidance groove  1531  also prevents the grounding bracket  150  from being interfered by the rotor body  110  in a mounting process. 
     The following describes a structure in which the outer ring  121  of the conductive bearing  120  indirectly interference fits with the inner wall of the shaft hole  111 . 
       FIG. 8  is a schematic diagram of a structure of a bearing housing in  FIG. 3 , and  FIG. 9  is a sectional view of  FIG. 8 . Refer to  FIG. 3 ,  FIG. 8 , and  FIG. 9 . The motor rotor  100  in this embodiment of this application may further include a bearing housing  140 . The bearing housing  140  is disposed in the shaft hole  111 , and the conductive bearing  120  is located in a mounting cavity  141  of the bearing housing  140 . An outer wall of the bearing housing  140  interference fits with the inner wall of the shaft hole  111 , and the outer ring  121  of the conductive bearing  120  interference fits with an inner wall of the bearing housing  140 . 
     In other words, the conductive bearing  120  is fastened in the shaft hole  111  of the rotor body  110  by using the bearing housing  140 , and the outer ring  121  of the conductive bearing  120  interference fits with the inner wall of the shaft hole  111  by using a side wall of the bearing housing  140 . In this way, the bearing housing  140 , the rotor body  110 , and the outer ring  121  of the conductive bearing  120  are static relative to each other. For example, in the process in which the rotor body  110  rotates around the axis at a high speed, the bearing housing  140  and the outer ring  121  of the conductive bearing  120  rotate synchronously with the rotor body  110 . 
     In this embodiment of this application, the bearing housing  140  is disposed in the shaft hole  111 , and the conductive bearing  120  is mounted in the bearing housing  140 . This facilitates assembling of the conductive bearing  120  in the shaft hole  111  of the rotor body  110 , and also improves axial stability of the conductive bearing  120  and the conductive pillar  130  in the shaft hole  111 . 
     In addition, the outer wall of the bearing housing  140  interference fits with the inner wall of the shaft hole  111 , and the outer ring  121  of the conductive bearing  120  interference fits with the inner wall of the bearing housing  140 , so that the bearing housing  140  is in closer contact with each of the rotor body  110  and the conductive bearing  120 . Therefore, it is ensured that the shaft current on the rotor body  110  can be successfully transmitted to the bearing housing  140  and the conductive bearing  120 , and assembling stability of the bearing housing  140  in the shaft hole  111  and assembling stability of the conductive bearing  120  in the bearing housing  140  are also improved. 
     Refer to  FIG. 3  and  FIG. 8 . Further, a cooling path  113  is formed between the outer wall of the bearing housing  140  and the inner wall of the shaft hole  111  in this embodiment of this application. The cooling path  113  extends in the axis direction of the rotor body  110 , and two ends of the cooling path  113  in an extension direction both communicate with the shaft hole  111  of the rotor body  110 . The cooling path  113  is used to allow a cooling medium to flow. It may be understood that the cooling medium may be oil or cooling water. 
     For example, a groove  144  is disposed on the outer wall of the bearing housing  140 , and two ends of the groove  144  run through two ends of the bearing housing  140  in an extension direction. In this way, an inner wall of the groove  144  and the inner wall of the shaft hole  111  jointly surround the cooling path  113 . The extension direction of the bearing housing  140  is consistent with the axis direction of the rotor body  110 . 
     It may be understood that the groove  144  may be a structure integrally injection molded when the bearing housing  140  is manufactured. Certainly, in some examples, cutting may be performed on the outer wall of the manufactured bearing housing  140  to form the groove  144  on a partial side wall. 
     In actual application, because the outer wall of the bearing housing  140  is a curved surface, a partial outer wall of the bearing housing  140  may be cut into a flat surface, and the flat surface may be considered as the groove  144  with a relatively shallow depth. Two sides of the flat surface in a circumferential direction of the bearing housing  140  abut on the inner wall of the shaft hole  111 , so that the flat surface and the inner wall of the shaft hole  111  surround the cooling path  113 . 
     When heat of the motor rotor  100  needs to be dissipated, the cooling medium such as oil may be introduced into the shaft hole  111  of the rotor body  110 . The oil flows from the first end of the rotor body  110  to the shaft hole  111 . When the oil flows to the bearing housing  140 , the oil may enter the cooling path  113  from one end of the cooling path  113  to perform heat exchange with the outer wall of the bearing housing  140 , is drained from the other end of the cooling path  113  to the shaft hole  111 , and is finally drained from the second end of the rotor body  110 . 
     It may be understood that the conductive bearing  120  and the conductive pillar  130  inside the bearing housing  140  transmit heat to the outer wall of the bearing housing  140  by using the inner wall of the bearing housing  140 . In this way, after heat exchange is performed between the oil in the cooling path  113  and the outer wall of the bearing housing  140 , heat of the bearing housing  140  and the conductive bearing  120  and the conductive pillar  130  inside the bearing housing  140  may be removed, to dissipate heat for the bearing housing  140 , the conductive bearing  120 , and the conductive pillar  130 . 
     In this embodiment of this application, the cooling path  113  is formed between the outer wall of the bearing housing  140  and the inner wall of the shaft hole  111 . In this way, the cooling medium that is introduced into the shaft hole  111  may enter the cooling path  113 , to cool the bearing housing  140 , the conductive bearing  120 , and the conductive pillar  130 . Therefore, the following case is avoided: The conductive bearing  120  is heated and expanded in the high-speed running process of the motor rotor  100 , and consequently the steel ball  122  in the conductive bearing  120  cannot rotate normally and a conductivity of the conductive grease decreases. Therefore, it is ensured that the conductive bearing  120  and the conductive grease are stable. 
     Still refer to  FIG. 3  and  FIG. 8 . The bearing housing  140  may include a bearing housing body  142  and a base  143 . An outer wall of the bearing housing body  142  interference fits with the inner wall of the shaft hole  111 . The bearing housing body  142  includes a first end and a second end that are disposed oppositely to each other in an extension direction. The first end of the bearing housing body  142  faces the grounding bracket  150 , and the first end is opened. The base  143  of the bearing housing  140  is disposed at the second end of the bearing housing body  142 . In other words, a first end of the bearing housing  140  is opened and faces the grounding bracket  150 , and a second end of the bearing housing  140  has the base  143 . The bearing housing body  142  and the base  143  jointly surround the mounting cavity  141  of the bearing housing  140 , and the conductive bearing  120  is located in the mounting cavity  141 . 
     It should be noted that the first end and the second end of the bearing housing body  142  may also be considered as the first end and the second end of the bearing housing  140 . 
     During specific assembling, the conductive bearing  120  may be mounted in the bearing housing  140  from an opening of the first end of the bearing housing  140 , and an end of the conductive pillar  130  extends into the mounting cavity  141  of the bearing housing  140  through the opening of the first end of the bearing housing  140 , and further interference fits with the inner ring  123  of the conductive bearing  120 . 
     In this embodiment of this application, an end of the bearing housing  140  that faces the grounding bracket  150  is opened, to facilitate assembling of the conductive bearing  120  and the conductive pillar  130 . In addition, the base  143  of the bearing housing  140  plays a role of positioning the conductive bearing  120  axially. In other words, provided that the conductive bearing  120  is assembled on the base  143 , positioning of the conductive bearing  120  in the bearing housing  140  can be completed. This improves assembling efficiency of the conductive bearing  120 . 
     An auxiliary hole (not shown in the figure) may be disposed on a side wall of the bearing housing body  142  that is close to the first end. The auxiliary hole is used to assist a mounting tool in grasping the bearing housing  140 . For example, when the bearing housing  140  needs to be mounted in the shaft hole  111  of the rotor body  110 , the mounting tool may extend into the auxiliary hole to exert force on the bearing housing  140 , so as to build the bearing housing  140  into a corresponding position in the shaft hole  111 . When the bearing housing  140  needs to be removed from the shaft hole  111  of the rotor body  110 , the mounting tool also extends into the auxiliary hole to grasp the bearing housing  140 , so as to quickly pull the bearing housing  140  out of the shaft hole  111 . 
     The bearing housing  140  in this embodiment of this application may be an integrally formed member, namely, the bearing housing body  142  and the base  143  of the bearing housing  140  are integrally injection molded, to improve structural strength of the bearing housing  140 . Certainly, in this embodiment of this application, that the bearing housing body  142  and the base  143  are disposed separately is not ruled out. For example, the base  143  may be fastened to the second end of the bearing housing body  142  through screw connection, clamping, or the like. 
     In an embodiment, an inner wall of the base  143  is recessed in a direction away from the first end of the bearing housing body  142  to form a limiting groove  1431 , and an end of the conductive pillar  130  extends into the limiting groove  1431  to limit radial movement of the conductive pillar  130  in the rotor body  110 . An opening size and a shape of the limiting groove  1431  may be respectively consistent with a radial size and a shape of the conductive pillar  130 . In this way, the outer wall of the conductive pillar  130  may be attached to an inner wall of the limiting groove  1431 , to further prevent an end of the conductive pillar  130  that faces the base  143  from shaking radially. 
     One end of the conductive pillar  130  internally passes through the positioning hole  151  of the grounding bracket  150 , and the other end of the conductive pillar  130  extends into the limiting groove  1431  of the bearing housing  140 . This effectively limits radial movement of the conductive pillar  130 , and prevents the conductive pillar  130  from shaking from side to side radially in the high-speed running process of the rotor body  110 . 
     Refer to  FIG. 9 . When the limiting groove  1431  is disposed, a partial region of the base  143  may protrude in a direction away from the first end of the bearing housing body  142 . In this case, a recess part is formed on the inner wall of the base  143 . The recess part may be used as the limiting groove  1431 , and an inner wall of the recess part is the inner wall of the limiting groove  1431 . A protrusion part is formed on an outer wall of the base  143 , and a side wall of the protrusion part may be understood as an outer wall of the limiting groove  1431 . 
     Certainly, in another example, a groove may be directly disposed on the inner wall of the base  143 , and the groove is used as the limiting groove  1431 . 
     It should be noted that the inner wall (an inner surface) of the base  143  is a surface of the base  143  that is located inside the bearing housing  140 , and the outer wall (an outer surface) of the base  143  is a surface of the base  143  that is located outside the bearing housing  140 . 
     Refer to  FIG. 4 . In this embodiment of this application, a step part  133  is formed on the side wall of the conductive pillar  130 , and the step part  133  is located between the grounding bracket  150  and the base  143  of the motor rotor  100 . In other words, after two ends of the conductive pillar  130  are respectively assembled in the grounding bracket  150  and the bearing housing  140 , the step part  133  on the conductive pillar  130  is located on a side of the grounding bracket  150  that faces the bearing housing  140 . A distance between the step part  133  and the grounding bracket  150  is a first distance (shown by h 1  in  FIG. 3 ). A distance between an outer peripheral surface of the limiting groove  1431  and the end of the conductive pillar  130  that faces the base  143  is a second distance (shown by h 2  in  FIG. 3 ). 
     It should be noted that the first distance h 1  is a vertical distance between a step surface (shown by a in  FIG. 4 ) of the step part  133  that faces the grounding bracket  150  and a surface of the body part  152  that faces the step part  133 . The second distance h 2  is a vertical distance between the outer peripheral surface of the limiting groove  1431  (shown by b in  FIG. 3  and  FIG. 9 ) and an end face of the conductive pillar  130  that faces the base  143 . 
     It should be noted that the outer peripheral surface of the limiting groove  1431  is an inner surface of the base  143  that is located outside the limiting groove  1431 . 
     The first distance h 1  is less than the second distance h 2 . In this way, when one end of the conductive pillar  130  moves axially to the grounding bracket  150  in the high-speed running process of the rotor body  110 , the other end of the conductive pillar  130  is still located in the limiting groove  1431  and is not separated from the limiting groove  1431 . This reduces a distance by which the conductive pillar  130  moves axially, and ensures axial stability of the conductive pillar  130 . 
     For example, when the first distance h 1  is zero, namely, when the step part  133  moves and abuts on the body part  152  of the grounding bracket  150 , the second distance h 1  is greater than zero, namely, the end of the conductive pillar  130  that faces the base  143  is still located in the limiting groove  1431  of the base  143 . Therefore, axial stability of the conductive pillar  130  is ensured, and radial stability of the conductive pillar  130  is also ensured. 
     Still refer to  FIG. 4 . A stop part  132  may extend from the outer wall of the conductive pillar  130  in a direction away from the axis. The conductive bearing  120  is located between the stop part  132  and the base  143 , and a distance between an end of the stop part  132  and the inner wall of the bearing housing  140  is less than a diameter of the steel ball  122  in the conductive bearing  120 . 
     It should be noted that the distance between an end of the stopper  132  and the inner wall of the bearing housing  140  is a distance (shown by h 3  in  FIG. 3 ) between an end of the stop part  132  that is away from the axis of the conductive pillar  130  and the inner wall of the bearing housing  140 , where h 3  is less than the diameter of the steel ball  122  in the conductive bearing  120 . In this way, after the steel ball  122  in the conductive bearing  120  drops from the conductive bearing  120 , the steel ball  122  does not drop between the stop part  132  and the inner wall of the bearing housing  140 , to ensure that the steel ball  122  does not drop from the first end of the bearing housing  140  to the outside of the rotor body  110 . 
     Refer to  FIG. 3 . To facilitate assembling of the bearing housing  140 , a boss  112  may be formed on the inner wall of the shaft hole  111 , and an end of the bearing housing  140  that is away from the grounding bracket  150  abuts on the boss  112 . For example, the base  143  of the bearing housing  140  abuts on the boss  112  on the inner wall of the rotor body  110 , to further limit axial movement of the bearing housing  140  in the rotor body  110 . 
     In addition, the boss  112  plays a role in quickly positioning assembling of the bearing housing  140  in the shaft hole  111 , namely, provided that the bearing housing  140  is placed downwards to abut on the boss  112 , positioning of the bearing housing  140  in the shaft hole  111  is completed. 
     Refer to  FIG. 1  and  FIG. 2 . An embodiment of this application further provides a motor, including a motor housing  200 , a main bearing  300 , and the foregoing motor rotor  100 . The motor housing  200  is sleeved on an outer wall of the motor rotor  100  by using the main bearing  300 . 
     In an embodiment, an inner ring of the main bearing  300  may interference fit with the outer wall of the motor rotor  100 , to ensure that the inner ring of the main bearing  300  is in closer contact with the motor rotor  100 , and ensure that the inner ring of the main bearing  300  and the motor rotor  100  are static relative to each other. Correspondingly, an outer ring of the main bearing  300  interference fits with an inner wall of the motor housing  200 , to ensure that the outer ring of the main bearing  300  is in closer contact with the motor housing  200 , and ensure that the outer ring of the main bearing  300  and the motor housing  200  are static relative to each other. 
     In this embodiment of this application, the foregoing motor rotor  100  is disposed in the motor, to prevent the main bearing  300  of the motor rotor  100  from being electrically corroded by a shaft current. In addition, because no concentrated stress occurs in a conductive bearing  120  of the motor rotor  100 , and the conductive bearing  120  is not subject to offset loading force, the conductive bearing  120  is prevented from being abnormally worn. Therefore, conductive grease is prevented from overflowing because sealing rings on the conductive bearing  120  are worn, a service life of the conductive bearing  120  is prolonged, it is ensured that the shaft current on the motor rotor  100  is successfully discharged by using the conductive bearing  120 , and the main bearing  300  is not electrically corroded, to ensure that the motor runs normally. 
     An embodiment of this application further provides a vehicle, including wheels and the foregoing motor. A motor rotor  100  of the motor is connected to the wheels to drive the wheels to rotate. For example, a rotation shaft of the motor rotor  100  may be connected to the wheels by using a transmission component, so that the rotation shaft of the motor rotates to output power, the transmission component transmits the power to the wheels, and therefore the wheels rotate. 
     In this embodiment of this application, the foregoing motor is mounted on the vehicle, so that it is ensured that the motor of the vehicle can work stably, to stably drive the wheels. 
     It should be noted that the vehicle in this embodiment of this application may include but is not limited to any one of an electric vehicle (EV), a battery electric vehicle (PEV/BEV), a hybrid electric vehicle (HEV), a range extended electric vehicle (REEV), a plug-in hybrid electric vehicle (PHEV), or a new energy vehicle (new energy vehicle). 
     In the descriptions of the embodiments of this application, it should be noted that, unless otherwise clearly specified and limited, terms “assemble”, “connected”, and “connection” should be understood in a broad sense. For example, the terms may be used for a fixed connection, an indirect connection through an intermediate medium, an internal connection between two elements, or an interaction relationship between two elements. Persons of ordinary skill in the art may understand specific meanings of the terms in the embodiments of this application based on specific cases. 
     In the specification, claims, and accompanying drawings of the embodiments of this application, the terms “first”, “second”, “third”, “fourth”, and so on (if existent) are intended to distinguish between similar objects but do not necessarily indicate a specific order or sequence.