Powertrain and electric vehicle

Abstract

The application provides a power assembly and an electric vehicle, and relates to the technical field of electric vehicles. The power assembly is used for driving the wheels of the electric vehicle. The inner ring of the bearing of the power assembly is used for fixedly connecting the rotating shaft of the power assembly. The cage and the plurality of balls of the bearing are distributed between the inner ring and the outer ring of the bearing. The plurality of pockets of the cage are used for accommodating at least part of the plurality of balls. The ratio of the difference between the length of the pocket along the circumference of the bearing and the diameter of the ball to the diameter of the ball is greater than or equal to 3%. The application adjusts the size relationship between the pocket and the ball, which is beneficial to reducing the risk of the bearing being stuck and worn, and improving the safety performance and service life of the bearing.

Description

Technical Field

[0001] This application relates to the field of electric vehicle technology, and in particular to a powertrain and an electric vehicle. Background Technology

[0002] In electric vehicles, the powertrain transmits power through the cooperation of multiple shafts between the drive motor and the reducer to drive the wheels. Bearings provide stable rotational support for the shafts, ensuring the reliability of the drive motor and reducer, and are an indispensable part of the powertrain. However, due to factors such as bearing installation precision and the complexity of operating conditions, the bearing balls and cages are prone to interference and collision, causing bearing jamming and wear, and shortening the bearing's service life. Summary of the Invention

[0003] This application provides a powertrain and electric vehicle that can improve the service life of bearings.

[0004] In a first aspect, embodiments of this application provide a powertrain for driving the wheels of an electric vehicle. The inner ring of a bearing in the powertrain is used to securely connect to the shaft of the powertrain. A cage and a plurality of balls are distributed between the inner and outer rings of the bearing, and a plurality of pockets in the cage are used to accommodate at least a portion of the plurality of balls.

[0005] Among them, the ratio of the difference between the length of a pocket along the circumference of the bearing and the diameter of a ball to the diameter of a ball is greater than or equal to 3%.

[0006] In this embodiment, the powertrain bearing is used to connect the powertrain's rotating shaft. The bearing allows the rotating shaft to rotate relative to the powertrain's housing, providing stable rotational support for the shaft. The bearing can transfer the load on the rotating shaft to a fixed structure such as the housing.

[0007] In this embodiment, a cage is used to separate a plurality of balls and to guide each ball to revolve at a stable speed. The cage includes a plurality of pockets spaced apart circumferentially along the bearing, each pocket for receiving at least a portion of a ball. The plurality of pockets are used to evenly distribute the plurality of balls between the inner and outer rings of the bearing.

[0008] During bearing operation, the leading and lagging motion of the balls relative to the pockets leads to frictional collisions between the balls and the pockets, deteriorating lubrication and increasing the coefficient of friction during bearing rolling. The repeated tensile forces exerted on the cage by the advancing and lagging sides of the balls may exceed fatigue strength, causing cage failure. This problem becomes increasingly severe as powertrain speeds increase. Bearing installation accuracy is one factor contributing to the imbalance between ball and cage speeds. When bearing misalignment results in a large relative tilt between the inner and outer rings, the balls experience additional forces as they revolve around the cage, causing them to impact and push against the cage, or be pushed by the cage. This can easily lead to bearing jamming and wear, ultimately damaging the cage. Adopting more meticulous and precise alignment control methods can improve bearing installation accuracy, preventing bearing failure due to cage or ball jamming. However, improvements to the bearing assembly process require the introduction of new tools and stricter control processes, increasing assembly costs.

[0009] This application embodiment reduces the risk of interference between the ball and the pocket by improving the bearing pocket without interfering with bearing assembly. Taking a single pocket as an example, the pocket is used to accommodate at least a portion of a ball. The ratio of the difference between the length of the pocket along the circumference of the bearing and the diameter of the ball to the diameter of the ball is greater than or equal to 3%.

[0010] In this embodiment, the difference between the circumferential length of a pocket and the diameter of a ball represents the size of the circumferential clearance between the pocket and the ball. By increasing the circumferential clearance between the pocket and the ball, even if there is a speed difference between the ball and the pocket, the pocket provides space for the ball to move circumferentially along the bearing, which helps the pocket and the ball to avoid misalignment and reduces frictional losses between them. By controlling the ratio of the difference between the circumferential length of the pocket and the diameter of the ball to the diameter of the ball, the circumferential clearance between the ball and the pocket can be adjusted according to the actual size of the ball, making the bearing suitable for different shafts in the powertrain. Furthermore, the circumferential clearance between the pocket and the ball also allows for lubricating oil flow; increasing this clearance improves the bearing's lubrication conditions.

[0011] The method for extending bearing life in this application embodiment does not depend on the bearing installation precision. Even when using traditional bearing assembly processes, this application embodiment can reduce the risk of interference and collision between the bearing balls and cage without increasing assembly costs, enabling the bearing to adapt to the high speed of the powertrain and improving the bearing's safety performance.

[0012] In one embodiment, the ratio of the difference between the length of a pocket along the circumference of the bearing and the diameter of a ball to the length of a pocket along the circumference of the bearing is greater than or equal to 2.9%.

[0013] In this embodiment, by controlling the ratio of the difference between the circumferential length of a pocket and the diameter of a ball to the circumferential length of a pocket, the circumferential clearance between a ball and a pocket can be adjusted according to the actual size of the pocket, thus avoiding continuous rigid compression between a ball and a pocket during the process of the ball moving ahead or behind the cage.

[0014] In one embodiment, the ratio of the difference between the length of a pocket along the circumference of the bearing and the diameter of a ball to the pitch circle diameter of the bearing is greater than or equal to 0.5%.

[0015] In this embodiment, the pitch circle diameter of the bearing refers to the diameter of the imaginary circle formed by connecting the centers of all the balls in the bearing. The pitch circle diameter is related to the outer diameter of the outer ring and the inner diameter of the inner ring. The pitch circle diameter may vary when the bearing is applied to different shafts. This embodiment provides a range of ratios between the circumferential length of the pocket and the difference between the diameter of a ball and the bearing's pitch circle diameter. This allows adjustment of the circumferential clearance between a pocket and a ball based on the different shafts to which the bearing is applied, thus improving the bearing's adaptability to different shafts.

[0016] In one embodiment, the length of a pocket along the circumferential direction of the bearing is greater than the length of a pocket along the axial direction of the bearing.

[0017] In this embodiment, the relatively large circumferential length of a pocket helps reduce the risk of jamming or wear between the pocket and a ball, thus extending the bearing's service life. The relatively small axial length of a pocket helps reduce the axial space occupied by the cage between the inner and outer rings of the bearing. Reducing the axial length of a pocket also enhances its ability to guide the movement of a single ball, improving the smoothness of bearing operation.

[0018] In one embodiment, the ratio of the difference between the length of each pocket along the circumference of the bearing and the diameter of each ball to the diameter of each ball is greater than or equal to 3%.

[0019] In this embodiment, applying the dimensional relationship between a pocket and a ball to each pocket and each ball of the bearing helps to improve the overall service life of the bearing and avoid fatigue damage to some pockets and balls due to frequent interference and collision. Uniformly adjusting the dimensional relationship between each pocket and each ball also helps to reduce the design and manufacturing difficulty of the bearing.

[0020] In one embodiment, the product of the length of each pocket along the circumference of the bearing and the number of pockets is less than 70% of the pitch circle circumference of the bearing.

[0021] In this embodiment, the pitch circle circumference is the circumference of an imaginary circle formed by connecting the centers of all the balls. The ratio of the product of the number of pockets and their circumferential length to the pitch circle circumference reflects the pocket density. By controlling the upper limit of this ratio, the number of pockets can be constrained. Reducing the number of pockets can reduce the difficulty of extending the circumferential length of multiple pockets.

[0022] In one embodiment, the bearing is a deep groove ball bearing or an angular contact ball bearing.

[0023] In the embodiments of this application, both the deep groove ball bearing and the angular contact ball bearing are ball bearings, and the rolling elements of the ball bearing are spherical balls, which helps to reduce the difficulty of adjusting the pocket and ball size. The balls of the ball bearing have point contact with the inner and outer rings, resulting in a low coefficient of friction, which helps to reduce energy loss caused by the bearing and improve the transmission efficiency of the powertrain.

[0024] In one embodiment, the powertrain includes a drive motor, the motor shaft of which is used to drive a reducer of the powertrain, and the inner ring of a bearing is used to fix the motor shaft.

[0025] In this embodiment, the powertrain's rotating shaft includes a motor shaft, which typically operates at a high speed. The motor shaft utilizes bearings provided in this embodiment. Due to the optimized reliability and service life of the bearings, they provide stable support for the motor shaft, facilitating its adaptation to the high-speed rotation of the motor shaft and reducing powertrain maintenance costs. Furthermore, the reduced risk of bearing jamming and wear helps control the temperature rise and energy loss of the drive motor, as well as decrease vibration and noise caused by the bearings in the drive motor, thus improving the powertrain's NVH performance.

[0026] In one embodiment, the powertrain includes a drive motor and a reducer, wherein the motor shaft of the drive motor is used to fixably connect to the input shaft of the reducer, and the inner rings of two bearings of the powertrain are used to fixably connect the motor shaft and the input shaft, respectively.

[0027] In this embodiment, the powertrain's rotating shafts include a motor shaft and an input shaft, both of which typically rotate at high speeds. The bearings for the motor shaft and input shaft utilize the bearings provided in this embodiment. Because the reliability and service life of these bearings are optimized, they are better suited to the high-speed rotation of the motor shaft and input shaft, ensuring stable power transmission between the drive motor and the reducer, and reducing powertrain maintenance costs. Furthermore, the reduced risk of bearing jamming and wear helps control temperature rise and energy loss in the drive motor and reducer, as well as decrease vibration and noise caused by the bearings in the drive motor and reducer, thus improving the powertrain's NVH performance.

[0028] In this embodiment, since both the motor shaft bearings and the input shaft bearings employ a strategy of adjusting the pocket and ball bearing dimensions, and the bearings on both shafts are of the same type, it simplifies the bearing adjustment process and reduces the manufacturing difficulty and cost of the bearings. Furthermore, bearings of the same type have similar frictional characteristics. When the motor shaft and input shaft are fixedly connected, their rotational speeds are the same, and torque is directly transmitted between them. Using the same type of bearings on the motor shaft and input shaft helps maintain synchronized vibration characteristics, improving the stability and reliability of the transmission process.

[0029] Secondly, embodiments of this application provide an electric vehicle, which includes a power battery and a powertrain as described in any embodiment of the first aspect, wherein the powertrain is used to receive power from the power battery and to drive the wheels of the electric vehicle.

[0030] In the embodiments of this application, the powertrain from any embodiment of the first aspect is applied to an electric vehicle. Because the dimensions of the powertrain bearings are optimized, the frictional loss of the bearings is reduced, which helps to improve the transmission efficiency of the powertrain and enhance the driving range of the electric vehicle. The service life and reliability of the powertrain bearings are improved, which helps to ensure the normal operation of the powertrain and enhances the safety performance of the electric vehicle. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments of this application will be described below.

[0032] Figure 1 This is a schematic diagram of an electric vehicle provided in an embodiment of this application; Figure 2 This is a schematic diagram of the powertrain provided in an embodiment of this application; Figure 3 This is a schematic diagram of the powertrain provided in an embodiment of this application; Figure 4 This is a schematic diagram of the bearing provided in an embodiment of this application; Figure 5 This is a cross-sectional view of the bearing provided in an embodiment of this application; Figure 6 This is a cross-sectional view of the bearing provided in an embodiment of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0034] For ease of understanding, the English abbreviations used in the embodiments of this application will be explained and described below.

[0035] NVH: An abbreviation for Noise, Vibration, and Harshness, referring to noise, vibration, and acoustic roughness, respectively, used to measure the design and manufacturing quality of vehicles.

[0036] Currently, powertrain bearings face the problem of easy wear of the cage and balls. To improve bearing life, this application provides a powertrain used to drive the wheels of an electric vehicle. The inner ring of the powertrain bearing is used to fix the powertrain shaft. The bearing cage and multiple balls are distributed between the inner and outer rings of the bearing, and multiple pockets of the cage are used to accommodate at least a portion of the balls. The ratio of the difference between the length of one pocket along the circumference of the bearing and the diameter of one ball to the diameter of one ball is greater than or equal to 3%. By adjusting the dimensional relationship between the pockets and the balls, this application reduces the risk of interference between the pockets and the balls, improving the safety performance and lifespan of the bearing. The powertrain provided in this application can be applied to electric vehicles.

[0037] Please see Figure 1 , Figure 1 This is a schematic diagram of the electric vehicle 1 provided in an embodiment of this application.

[0038] The electric vehicle 1 in this embodiment includes a powertrain 10 and a power battery 20. In this embodiment, the electric vehicle 1 refers to a wheeled device driven or towed by a power unit. The power battery 20 is used to supply power to the powertrain 10; the power battery 20 can also be referred to as a battery pack. The powertrain 10 is the power source of the electric vehicle 1 and is used to drive the wheels 30 of the electric vehicle 1.

[0039] In one embodiment, the electric vehicle 1 further includes a frame 40 for mounting the powertrain 10 and the power battery 20. The frame 40 serves as the structural skeleton of the electric vehicle 1, capable of withstanding environmental loads from both inside and outside the electric vehicle 1.

[0040] It should be noted that, Figure 1 The electric vehicle 1 is shown schematically only, including the powertrain 10, power battery 20, wheels 30 and frame 40, and does not represent the specific structure, size and positional relationship of the powertrain 10, power battery 20, wheels 30 and frame 40.

[0041] Please see Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the powertrain 10 provided in an embodiment of this application. Figure 3 This is a schematic diagram of the powertrain 10 provided in the embodiments of this application.

[0042] The powertrain 10 in this embodiment includes a drive motor 300 and a reducer 400, wherein the drive motor 300 drives the wheels via the reducer 400. It should be noted that... Figure 2 and Figure 3 This does not represent the specific structure and dimensions of the drive motor 300 and the reducer 400.

[0043] The drive motor 300 is used to convert electrical energy into mechanical energy to generate driving torque. In one embodiment, the drive motor 300 includes a motor shaft 310, a motor rotor, and a motor stator. The motor shaft 310 is used to fixably connect to the inner circumferential surface of the motor rotor. The windings of the motor stator are used to receive alternating current. After receiving alternating current, the motor stator drives the motor rotor to rotate, thereby driving the motor shaft 310 to rotate.

[0044] The reducer 400 is used to transmit the power output from the drive motor 300 to the wheels. The reducer 400 reduces the speed of the power output from the drive motor 300, increasing the output torque. Depending on the different architectures used, the reducer 400 can be divided into parallel shaft reducers and planetary reducers. In a parallel shaft reducer, the input and output ends are arranged radially spaced, and the input shaft 410 is typically fixedly connected to the motor shaft 310. In a planetary reducer, the input and output ends are arranged coaxially.

[0045] In one embodiment, the powertrain 10 further includes a motor controller for controlling at least one of the drive motor 300 and the planetary gearbox 400. In one embodiment, the motor controller is used to convert between direct current (DC) and alternating current (AC). Exemplarily, the motor controller can convert DC power supplied by the power battery into AC power and then transmit the AC power to the drive motor 300.

[0046] In one embodiment, the powertrain 10 also includes a differential, or the reducer 400 of the powertrain 10 has a differential function. When the electric vehicle is turning or traveling on uneven surfaces, the differential or the reducer 400 with a differential function can cause the wheels on different sides to rotate at different speeds.

[0047] Bearing 100 is a crucial support component for the drive motor 300 and the reducer 400. It supports the rotational movement of the shaft 200 in both the drive motor 300 and the reducer 400, ensuring stable power transmission. The service life of bearing 100 directly affects the performance of the powertrain 10. This embodiment of the application improves the bearing 100 of the powertrain 10, thereby mitigating bearing wear and enhancing the transmission efficiency and safety of the powertrain 10. It should be noted that... Figure 2 and Figure 3 This does not represent the specific structure and dimensions of bearing 100.

[0048] The powertrain 10 of the embodiments of this application is described in detail below.

[0049] Please continue reading. Figure 2 and Figure 3 The bearing 100 of the powertrain 10 is used to connect the shaft 200 of the powertrain 10. The bearing 100 allows the shaft 200 to rotate relative to the housing of the powertrain 10, providing stable rotational support for the shaft 200. In one embodiment, the shaft 200 of the powertrain 10 may refer to at least one of the motor shaft 310 of the drive motor 300 or the input shaft 410 of the reducer 400.

[0050] Please see Figures 4 to 6 , Figure 4 This is a schematic diagram of the bearing 100 provided in an embodiment of this application. Figure 5 This is a cross-sectional view of the bearing 100 provided in an embodiment of this application. Figure 6 This is a cross-sectional view of the bearing 100 provided in the embodiment of this application.

[0051] The bearing 100 includes an inner ring 130, an outer ring 140, a cage 110, and a plurality of balls 120. The cage 110 and the plurality of balls 120 surround the outer periphery of the inner ring 130 and the inner periphery of the outer ring 140. The inner ring 130 is used to securely connect the shaft 200 of the powertrain 10. In one embodiment, the outer ring 140 is used to securely connect the housing of the powertrain 10. The bearing 100 can transfer the load borne by the shaft 200 to a fixed structure such as the housing.

[0052] The cage 110 is used to separate the plurality of balls 120 and guide each ball 120 to revolve at a stable speed. The cage 110 includes a plurality of pockets 111 spaced apart along the circumferential direction C of the bearing 100, each pocket 111 accommodating at least a portion of a ball 120. The plurality of pockets 111 are used to evenly distribute the plurality of balls 120 between the inner ring 130 and the outer ring 140 of the bearing 100. In one embodiment, the cage may be a split structure, with two separate substructures of the cage being detachably connected by riveting or other means. In one embodiment, the cage may also be a one-piece structure, and the cage may be a crown-shaped cage. In one embodiment, the cage may be made of steel or plastic.

[0053] During the operation of bearing 100, the leading and lagging motion of the balls 120 relative to the pocket 111 causes frictional collisions between the balls 120 and the pocket 111, resulting in deterioration of the lubrication condition and thus increasing the coefficient of friction when bearing 100 rolls. The repeated tensile forces exerted on the cage 110 by the advancing and lagging sides of the balls 120 may exceed the fatigue strength, leading to cage 110 failure. In particular, as the speed of powertrain 10 continues to increase, the interference problem between balls 120 and pocket 111 becomes increasingly serious. The installation accuracy of bearing 100 is one of the factors causing the imbalance in the rotational speeds of balls 120 and cage 110. When bearing 100 is misaligned, resulting in a large relative tilt between the inner ring 130 and the outer ring 140, the balls 120 will experience additional forces during their revolution with the cage 110. This can cause the balls 120 to impact and push the cage 110, or be pushed by the cage 110, easily leading to jamming and wear of the bearing 100, and ultimately damage to the cage 110. By employing more meticulous and precise alignment control methods, the installation accuracy of bearing 100 can be improved, thus avoiding bearing 100 failure due to jamming of the cage 110 or balls 120. However, improvements to the bearing 100 assembly process require the introduction of new tools and stricter control processes, increasing the assembly cost of bearing 100.

[0054] This embodiment of the application reduces the risk of interference between the ball 120 and the pocket 111 by improving the pocket 111 of the bearing 100 without interfering with the assembly of the bearing 100. Taking the pocket 111a as an example, the pocket 111a is used to accommodate at least a portion of the ball 120a. The ratio of the difference between the length D1 of the pocket 111a along the circumferential direction of the bearing 100 and the diameter D2 of the ball 120a to the diameter D2 of the ball 120a is greater than or equal to 3%.

[0055] In this embodiment, the difference between D1 and D2 represents the size of the circumferential clearance between the pocket 111a and the ball 120a. By increasing the circumferential clearance between the pocket 111a and the ball 120a, even if there is a speed difference between the ball 120a and the pocket 111a, the pocket 111a provides space for the ball 120a to move circumferentially along the bearing 100, which helps the pocket 111a and the ball 120a to avoid misalignment and reduces frictional loss between them. By controlling the ratio of the difference between D1 and D2 to D2, the circumferential clearance between the ball 120a and the pocket 111a can be adjusted according to the actual size of the ball 120a, making the bearing 100 suitable for different shafts 200 of the powertrain 10. In addition, the circumferential clearance between the pocket 111a and the ball 120a allows lubricating oil to flow, and increasing the circumferential clearance between the pocket 111a and the ball 120a is beneficial to improving the lubrication conditions of the bearing 100.

[0056] The method for improving the service life of bearing 100 in this application embodiment does not depend on the installation accuracy of bearing 100. Even if the traditional bearing 100 assembly process is used, this application embodiment can reduce the risk of interference and collision between the balls 120 and cage 110 of bearing 100 without increasing assembly costs, so that bearing 100 can adapt to the high speed of powertrain 10 and improve the safety performance of bearing 100.

[0057] It should be noted that, Figure 4 The bearing 100 is shown schematically only and does not represent the specific number of balls 120.

[0058] In one embodiment, to control the ratio of the difference between D1 and D2 to D2, D1 can be increased only, D2 can be decreased only, or both D1 and D2 can be increased simultaneously. When only the circumferential length D1 of the pocket 111a is increased, since the diameter D2 of the ball 120a and the radial length of the pocket 111a remain unchanged, modifications to the structure and dimensions of the inner ring 130 and outer ring 140 of the bearing 100 can be avoided.

[0059] Please continue reading. Figure 6 In one embodiment, the ratio of the difference between the length D1 of the pocket 111a along the circumferential direction of the bearing 100 and the diameter D2 of the ball 120a to the length D1 of the pocket 111a along the circumferential direction of the bearing 100 is greater than or equal to 2.9%.

[0060] In this embodiment of the application, by controlling the ratio of the difference between D1 and D2 to D1, the circumferential gap between the ball 120a and the pocket 111a can be adjusted according to the actual size of the pocket 111a, so as to avoid continuous rigid compression between the ball 120a and the pocket 111a during the process of the ball 120a moving ahead or behind the cage 110.

[0061] Please continue reading. Figure 6 In one embodiment, the ratio of the diameter D2 of the ball 120a to the length D1 of the pocket 111a along the circumferential direction of the bearing 100 is less than 98%.

[0062] In this embodiment of the application, by adjusting the upper limit of the ratio of D2 to D1, it is beneficial to provide clearance space for the ball 120a in the pocket 111a, and avoid mutual wear between the ball 120a and the pocket 111a due to the imbalance of the rotational speed between the ball 120a and the cage 110.

[0063] Please continue reading. Figure 6 In one embodiment, the ratio of the diameter D2 of the ball 120a to the length D1 of the pocket 111a along the circumferential direction of the bearing 100 is greater than or equal to 90%.

[0064] In this embodiment, the circumferential length of the pocket 111a cannot be increased indefinitely. The circumferential clearance between the pocket 111a and the ball 120a is used to compensate for the speed difference between the ball 120a and the cage 110, preventing the ball 120a from jamming. However, if the circumferential length of the pocket 111a is too large, the cage 110 will have difficulty effectively guiding the ball 120a. An excessively large circumferential clearance between the pocket 111a and the ball 120a provides excessive relative motion freedom for the ball 120a, which will amplify the small speed fluctuations of the ball 120a into high-intensity impact loads. In this embodiment, adjusting the lower limit of the ratio of D2 to D1 is beneficial to improving the smoothness of the rotation of the ball 120. In addition, controlling the size of the ratio of D2 to D1 can also prevent the pocket 111a from occupying too much circumferential space in the bearing 100, reducing the difficulty of arranging multiple balls 120 between the inner ring 130 and the outer ring 140.

[0065] Please continue reading. Figure 5 and Figure 6 In one embodiment, the ratio of the difference between the length D1 of the pocket 111a along the circumferential direction of the bearing 100 and the diameter D2 of the ball 120a to the pitch circle diameter P of the bearing 100 is greater than or equal to 0.5%.

[0066] In this embodiment, the pitch circle diameter P of the bearing 100 refers to the diameter of the imaginary circle formed by connecting the centers of all the balls 120 in the bearing 100. The pitch circle diameter P of the bearing 100 is related to the outer diameter of the outer ring 140 and the inner diameter of the inner ring 130 of the bearing 100. When the bearing 100 is applied to different shafts 200, the pitch circle diameter P of the bearing 100 may change. This embodiment provides a range of ratios of the difference between D1 and D2 to P, which allows adjustment of the circumferential clearance between the pocket 111a and the balls 120a based on different shafts 200 to which the bearing 100 is applied, thereby improving the adaptability of the bearing 100 to different shafts 200.

[0067] In one embodiment, the length D1 of the pocket 111a along the circumferential direction of the bearing 100 is greater than the length of the pocket 111a along the axial direction O of the bearing 100.

[0068] In this embodiment, the circumferential length of the pocket 111a is relatively large, which helps reduce the risk of jamming or wear between the pocket 111a and the ball 120a, thus extending the service life of the bearing 100. The axial length of the pocket 111a is relatively small, which helps reduce the axial space occupied by the cage 110 between the inner ring 130 and the outer ring 140 of the bearing 100. Reducing the axial length of the pocket 111a also helps enhance its ability to guide the movement of the ball 120a, improving the smoothness of the bearing 100's operation.

[0069] In one embodiment, the ratio of the difference between the length D1 of each pocket 111 along the circumferential direction of the bearing 100 and the diameter D2 of each ball 120 to the diameter D2 of each ball 120 is greater than or equal to 3%.

[0070] In one embodiment, the ratio of the difference between the length D1 of each pocket 111 along the circumferential direction of the bearing 100 and the diameter D2 of each ball 120 to the length D1 of each pocket 111 along the circumferential direction of the bearing 100 is greater than or equal to 2.9%.

[0071] In one embodiment, the ratio of the diameter D2 of each ball 120 to the length D1 of each pocket 111 along the circumference of the bearing 100 is less than 98%.

[0072] In one embodiment, the ratio of the diameter D2 of each ball 120 to the length D1 of each pocket 111 along the circumference of the bearing 100 is greater than or equal to 90%.

[0073] In one embodiment, the ratio of the difference between the length D1 of each pocket 111 along the circumferential direction of the bearing 100 and the diameter D2 of each ball 120 to the pitch circle diameter P of the bearing 100 is greater than or equal to 0.5%.

[0074] In one embodiment, the length D1 of each pocket 111 along the circumferential direction of the bearing 100 is greater than the length of each pocket 111 along the axial direction O of the bearing 100.

[0075] In this embodiment, applying the dimensional relationship between the pocket 111a and the ball 120a to each pocket 111 and each ball 120 of the bearing 100 is beneficial to improving the overall service life of the bearing 100 and avoiding fatigue damage to some pockets 111 and balls 120 due to frequent interference and collision. Uniformly adjusting the dimensional relationship between each pocket 111 and each ball 120 also helps to reduce the design and manufacturing difficulty of the bearing 100.

[0076] In one embodiment, the product of the length D1 of each pocket 111 along the circumference of the bearing 100 and the number of pockets 111 is less than 70% of the pitch circle circumference of the bearing 100.

[0077] In this embodiment, the pitch circle circumference is the circumference of the imaginary circle formed by connecting the centers of all the balls 120. The ratio of the product of the number of pockets 111 and their circumferential length to the pitch circle circumference reflects the arrangement density of the pockets 111. By controlling the upper limit of this ratio, the number of pockets 111 can be constrained. Reducing the number of pockets 111 can reduce the difficulty of extending the circumferential length of multiple pockets 111.

[0078] In one embodiment, bearing 100 is a deep groove ball bearing or an angular contact ball bearing.

[0079] In this embodiment, both the deep groove ball bearing and the angular contact ball bearing are ball bearings, and the rolling elements of the ball bearing are spherical balls 120, which helps to reduce the difficulty of adjusting the size of the pocket 111 and the balls 120. The balls 120 of the ball bearing have point contact with the inner ring 130 and the outer ring 140, resulting in a low coefficient of friction, which helps to reduce the energy loss caused by the bearing 100 and improve the transmission efficiency of the powertrain 10.

[0080] Please continue reading. Figure 2 and Figure 3 In one embodiment, the inner ring 130 of a bearing 100 of the powertrain 10 is used to securely connect to the motor shaft 310.

[0081] In this embodiment, the powertrain 10's rotating shaft 200 includes a motor shaft 310, which typically operates at a high speed. The motor shaft 310 utilizes a bearing 100 provided in this embodiment. Because the bearing 100's reliability and service life are optimized, it provides stable support for the motor shaft 310, facilitating its adaptation to the high-speed rotation of the motor shaft and reducing the maintenance costs of the powertrain 10. Furthermore, the reduced risk of bearing jamming and wear helps control the temperature rise and energy loss of the drive motor 300, and decreases vibration and noise caused by the bearing 100 within the drive motor 300, thus improving the NVH performance of the powertrain 10.

[0082] Please continue reading. Figure 2 In one embodiment, the inner rings 130 of the two bearings 100 of the powertrain 10 are used to fix the motor shaft 310 and the input shaft 410, respectively.

[0083] In this embodiment, the powertrain 10's rotating shaft 200 includes a motor shaft 310 and an input shaft 410, both of which typically rotate at high speeds. The bearings 100 of the motor shaft 310 and input shaft 410 are those provided in this embodiment. Because the reliability and service life of the bearings 100 are optimized, they are better suited to the high-speed rotation of the motor shaft 310 and input shaft 410, ensuring stable power transmission between the drive motor 300 and the reducer 400, and reducing the maintenance costs of the powertrain 10. Furthermore, the reduced risk of bearing jamming and wear helps control the temperature rise and energy loss of the drive motor 300 and reducer 400, as well as decrease vibration and noise caused by the bearings 100 in the drive motor 300 and reducer 400, thus improving the NVH performance of the powertrain 10.

[0084] In this embodiment, since both the bearing 100 of the motor shaft 310 and the bearing 100 of the input shaft 410 employ a strategy of adjusting the size of the pocket 111 and the ball 120, the bearings 100 of the two rotating shafts 200 are of the same type. This simplifies the adjustment process of the bearings 100 and reduces the processing difficulty and cost of the bearings 100. Furthermore, bearings of the same type have similar frictional characteristics. When the motor shaft 310 and the input shaft 410 are fixedly connected, and their rotational speeds are the same, torque is directly transmitted between them. Using the same type of bearing 100 for the motor shaft 310 and the input shaft 410 helps maintain synchronized vibration characteristics, improving the stability and reliability of the transmission process.

[0085] The effects of the value of (D1-D2) / D2 on the bearing will be explained below with reference to Examples 1-4 and Comparative Examples 1-7 in Table 1.

[0086] Table 1. Dimensional parameters of the bearings

[0087] The bearings in Example 1 and Comparative Examples 1-2 have the same inner and outer diameters and axial lengths. The bearings in Example 2 and Comparative Example 3 have the same inner and outer diameters and axial lengths. The bearings in Example 3 and Comparative Examples 4-5 have the same inner and outer diameters and axial lengths. The bearings in Example 4 and Comparative Examples 6-7 have the same inner and outer diameters and axial lengths. Under the same test conditions, the value of (D1-D2) / D2 in Examples 1-4 is 3%, which avoids the situation of the bearing pocket and ball jamming, while the bearings in Comparative Examples 1-7 exhibit jamming.

[0088] This application adjusts the range of (D1-D2) / D2 to be greater than or equal to 3%, which reduces the risk of interference between the pocket and the balls when the bearings have different inner and outer diameters and axial lengths, thus improving the service life and safety performance of the bearings.

[0089] The influence of the value of (D1-D2) / P on the bearing will be explained below with reference to Examples 5-8 and Comparative Examples 8-13 in Table 2.

[0090] Table 2 Dimensional parameters of bearings

[0091] The bearings in Example 5 and Comparative Examples 8-9 have the same inner and outer diameters and axial lengths. The bearings in Example 6 and Comparative Example 10 have the same inner and outer diameters and axial lengths. The bearings in Example 7 and Comparative Examples 11-12 have the same inner and outer diameters and axial lengths. The bearings in Example 8 and Comparative Example 13 have the same inner and outer diameters and axial lengths. Under the same test conditions, the value of (D1-D2) / P in Examples 5-8 is 0.5%, which avoids the risk of jamming between the bearing housing and the ball bearing, while the bearings in Comparative Examples 1-7 exhibit jamming.

[0092] This application adjusts the range of (D1-D2) / P to be greater than or equal to 0.5%, which reduces the risk of interference between the pocket and the balls when the bearings have different inner and outer diameters and axial lengths, thus improving the service life and safety performance of the bearings.

[0093] The powertrain and electric vehicle provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and embodiments of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in specific embodiments and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A powertrain, characterized by, The powertrain is used to drive the wheels of an electric vehicle. The inner ring of the powertrain's bearing is used to securely connect to the powertrain's shaft. A cage and a plurality of balls are distributed between the inner and outer rings of the bearing. A plurality of pockets in the cage are used to accommodate at least a portion of the plurality of balls. Wherein: The ratio of the difference between the length of one of the pockets along the circumference of the bearing and the diameter of one of the balls to the diameter of one of the balls is greater than or equal to 3%.

2. The powertrain of claim 1, wherein, The ratio of the difference between the length of the pocket along the circumference of the bearing and the diameter of the ball to the length of the pocket along the circumference of the bearing is greater than or equal to 2.9%.

3. The powertrain of any one of claims 1 or 2, wherein, The ratio of the difference between the length of the pocket along the circumference of the bearing and the diameter of the ball to the pitch circle diameter of the bearing is greater than or equal to 0.5%.

4. The powertrain according to any one of claims 1-3, characterized in that, The length of one pocket along the circumferential direction of the bearing is greater than the length of the other pocket along the axial direction of the bearing.

5. The powertrain according to any one of claims 1-4, characterized in that, The ratio of the difference between the length of each pocket along the circumference of the bearing and the diameter of each ball to the diameter of each ball is greater than or equal to 3%.

6. The powertrain according to claim 5, characterized in that, The product of the length of each pocket along the circumference of the bearing and the number of pockets is less than 70% of the pitch circle circumference of the bearing.

7. The powertrain according to any one of claims 1-6, characterized in that, The bearing is a deep groove ball bearing or an angular contact ball bearing.

8. The powertrain according to any one of claims 1-7, characterized in that, The powertrain includes a drive motor, the motor shaft of which is used to drive the reducer of the powertrain, and the inner ring of the bearing is used to fix the motor shaft.

9. The powertrain according to any one of claims 1-7, characterized in that, The powertrain includes a drive motor and a reducer. The motor shaft of the drive motor is used to fixably connect to the input shaft of the reducer. The inner rings of the two bearings of the powertrain are used to fixably connect the motor shaft and the input shaft, respectively.

10. An electric vehicle, characterized in that, The electric vehicle includes a power battery and a powertrain as described in any one of claims 1-9, the powertrain being used to receive power from the power battery and to drive the wheels of the electric vehicle.

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