Planetary reducer, powertrain and electric vehicle

Abstract

The application provides a planetary reducer, a power assembly and an electric vehicle, and relates to the technical field of electric vehicles. The planetary reducer is used for driving connection of a driving motor of an electric vehicle. A planetary wheel set of the planetary reducer comprises a planetary wheel and a planetary shaft. The planetary wheel is used for driving the planetary shaft to rotate through a needle roller bearing of the planetary reducer. A plurality of needles of the needle roller bearing are arranged around an inner circumferential side of the planetary wheel and an outer circumferential side of the planetary shaft. The ratio of the diameter of each needle to the inner diameter of the planetary wheel is less than or equal to 0.183. The application adjusts the size relationship between the needle roller bearing and the planetary wheel, which is beneficial to reducing the friction loss of the needle roller bearing and improving the transmission efficiency of the planetary reducer.

Description

Technical Field

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

[0002] In electric vehicles, the powertrain transmits power from the drive motor to the wheels via planetary gearboxes. Bearings provide stable rotational support for the planetary gearboxes, ensuring their reliable operation and making them an indispensable part of the powertrain.

[0003] However, bearing friction torque is one of the main sources of mechanical losses in powertrains. The high-speed requirements of the electric vehicle industry for powertrains can easily lead to increased bearing friction torque, thus requiring improvements in powertrain transmission efficiency. Summary of the Invention

[0004] This application provides a planetary reducer, powertrain, and electric vehicle that reduces frictional torque and improves transmission efficiency.

[0005] In a first aspect, embodiments of this application provide a planetary reducer for driving a drive motor of an electric vehicle. The planetary gear set of the planetary reducer includes planetary gears and planetary shafts. The planetary gears drive the planetary shafts to rotate via needle roller bearings in the planetary reducer, with multiple needle rollers of the needle roller bearings surrounding the inner circumference of the planetary gears and the outer circumference of the planetary shafts.

[0006] The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is less than or equal to 0.183.

[0007] In this embodiment, the bearing is a crucial supporting component of the planetary reducer, supporting the rotational motion of the planetary gears and planetary shafts to ensure stable power transmission. The bearing, connected to the planetary gears and planetary shafts, needs to be installed between them, placing strict requirements on the radial space occupied by the bearing. This embodiment uses needle roller bearings to connect the planetary gears and planetary shafts. Unlike ball bearings, needle roller bearings use slender needles as rolling elements, adapting to the limited installation space on the inner circumference of the planetary gears, thus meeting the miniaturization requirements of the planetary reducer. Furthermore, multiple needles of the needle roller bearing surround the inner circumference of the planetary gears and the outer circumference of the planetary shafts, with line contact between the needles and the planetary gears and planetary shafts. This effectively withstands the radial force during planetary gear meshing, helping to prevent premature bearing failure.

[0008] Existing planetary gear reducers typically focus on improving the strength and reliability of bearings. However, bearing friction losses are also a significant issue in planetary gear reducers. The bearing losses in planetary gear reducers are generally greater than those in parallel shaft reducers. Bearings continuously participate in the transmission process of a planetary gear reducer, and friction losses increase with load and speed, making the frictional torque generated by the bearings one of the main sources of mechanical losses in the powertrain.

[0009] This application embodiment reduces the frictional loss of the needle roller bearing by adjusting the ratio of the needle roller diameter to the inner diameter of the planetary gear. By controlling the upper limit of this ratio, excessively thick needle rollers can be avoided. This application embodiment sets the upper limit of the ratio of the needle roller diameter to the inner diameter of the planetary gear to 0.183. This reduces the inertial force of the needle roller and the contact area between the needle roller and the planetary gears and planetary shaft without changing the overall layout of the planetary reducer, thereby reducing energy loss caused by the needle roller bearing and improving the transmission efficiency of the planetary reducer. Controlling the needle roller diameter based on the inner diameter of the planetary gear also helps the needle roller bearing adapt to the installation space on the inner circumference of the planetary gear, reducing the installation difficulty of the needle roller bearing.

[0010] In one embodiment, the inner diameter of the planetary gears is less than or equal to 25 mm. The ratio of the diameter of each needle roller to the inner diameter of the planetary gears is less than or equal to 0.18.

[0011] In this embodiment, by adjusting the upper limit of the ratio of the needle roller diameter to the inner diameter of the planetary gear, the needle roller diameter can be constrained, which helps to reduce the inertial force of the needle roller and the contact area between the needle roller and the raceway, thereby reducing the frictional torque.

[0012] In this embodiment, the ratio of the needle roller diameter to the inner diameter of the planetary gear also affects the installation difficulty of the needle roller bearing. Since the installation space on the inner circumference of the planetary gear is limited, setting an upper limit for the ratio of the needle roller diameter to the inner diameter of the planetary gear allows the needle roller bearing to adapt to the installation space on the inner circumference of the planetary gear, ensuring a reasonable needle roller arrangement space while balancing load-bearing capacity and smooth operation.

[0013] In one embodiment, the ratio of the diameter of each needle roller to the inner diameter of the planetary gear is greater than or equal to 0.165.

[0014] In this embodiment, the needle roller serves as the load-bearing element of the needle roller bearing. If the diameter of the needle roller is too small, its load-bearing capacity will be insufficient, making it difficult to meet the torque transmission requirements of the planetary gears. Adjusting the lower limit of the ratio of the needle roller diameter to the inner diameter of the planetary gears helps to ensure the strength of the needle roller bearing and extend its service life.

[0015] In one embodiment, the ratio of the diameter of each needle roller to the inner diameter of the planetary gear is greater than or equal to 0.174. The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is less than or equal to 0.178.

[0016] In this embodiment of the application, when the inner diameter of the planetary gear is less than or equal to 25 mm, the ratio of the needle roller diameter to the inner diameter of the planetary gear is set to a range of 0.174 to 0.178, which is beneficial to both reduce frictional torque and improve reliability.

[0017] In one embodiment, the cage of the needle roller bearing is used to mount and separate multiple needle rollers, and at least one of the cage and the planetary shaft has a safety factor greater than 1.

[0018] In this embodiment, both the needle roller and the planetary shaft are located on the inner circumference of the planetary gear. If the ratio of the needle roller diameter to the inner diameter of the planetary gear is too large, it indicates that the needle roller occupies a large space on the inner circumference of the planetary gear, requiring the planetary shaft diameter to be shortened to meet the installation conditions of the needle roller bearing. However, if the planetary shaft diameter is too small, the planetary shaft itself will lack sufficient strength. This embodiment, by adjusting the upper limit of the ratio of the needle roller diameter to the inner diameter of the planetary gear, helps to enhance the bending resistance of the planetary shaft and improve its safety factor.

[0019] In this embodiment, if the ratio of the needle roller diameter to the planetary gear inner diameter is too large, the gap between the needle roller and the cage will decrease due to the increased needle roller diameter, leading to increased centrifugal force on the needle roller and accelerated wear on both the needle roller and the cage. This embodiment, by adjusting the upper limit of the ratio of the needle roller diameter to the planetary gear inner diameter, helps to alleviate cage wear and improve the cage's safety factor.

[0020] In one embodiment, the inner diameter of the planetary gear is greater than 25 mm, and the inner diameter of the planetary gear is less than or equal to 35 mm.

[0021] The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is greater than or equal to 0.157.

[0022] In this embodiment, adjusting the diameter of the needle roller based on the inner diameter of the planetary gear is beneficial to improving the load-bearing capacity of the needle roller bearing and extending its service life.

[0023] In one embodiment, the ratio of the diameter of each needle roller to the inner diameter of the planetary gear is greater than or equal to 0.165. The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is less than or equal to 0.174.

[0024] In the embodiments of this application, when the inner diameter of the planetary gear is greater than 25 mm and less than or equal to 35 mm, the ratio of the needle roller diameter to the inner diameter of the planetary gear is set to a range of 0.165 to 0.174, which is beneficial to both reduce frictional torque and improve reliability.

[0025] In one embodiment, the cage of the needle roller bearing is used to mount and separate multiple needle rollers, and the safety factor of each of the cage and the planetary shaft is greater than or equal to 1.

[0026] In this embodiment, planetary gears surround the outer periphery of the needle rollers and the planetary shaft. The larger inner diameter of the planetary gears increases the mounting space provided by the inner periphery of the planetary gears for the planetary shaft. By controlling the upper limit of the ratio of the needle roller diameter to the inner diameter of the planetary gears, the needle roller diameter can be prevented from becoming too large, allowing for an increase in the diameter of the planetary shaft, which is beneficial for enhancing the structural strength of the planetary shaft.

[0027] In this embodiment, if the ratio of the needle roller diameter to the planetary gear inner diameter is too large, the gap between the needle roller and the cage will decrease due to the increased needle roller diameter, leading to increased centrifugal force on the needle roller and accelerated wear on both the needle roller and the cage. This embodiment, by adjusting the upper limit of the ratio of the needle roller diameter to the planetary gear inner diameter, helps to alleviate cage wear and improve the cage's safety factor.

[0028] In one embodiment, the product of the number of needle rollers and the diameter of each needle roller is less than or equal to 0.7 times the pitch circumference of the needle roller bearing.

[0029] In this embodiment, the pitch circle circumference is the circumference of the imaginary circle formed by connecting the centers of all the needle rollers. The number of needle rollers can be constrained by controlling the upper limit of the ratio of the product of the number of needle rollers and their diameter to the pitch circle circumference. Reducing the number of needle rollers allows for sufficient circumferential clearance between adjacent rollers, preventing interference between them. Increased circumferential clearance between adjacent rollers also facilitates the flow of lubricating oil in the needle roller bearing, improving lubrication conditions. A reduced number of needle rollers results in a corresponding reduction in the number of cage pockets, which helps improve the structural strength of the cage.

[0030] In one embodiment, the product of the number of needle rollers and the diameter of each needle roller is less than or equal to 0.67 in ratio to the pitch circumference of the needle roller bearing.

[0031] In this embodiment, the number of needle rollers can be constrained by controlling the upper limit of the ratio of the product of the number and diameter of the needle rollers to the pitch circle circumference. Reducing the number of needle rollers allows for sufficient circumferential clearance between adjacent needle rollers, preventing interference between them. Increased circumferential clearance between adjacent needle rollers also facilitates the flow of lubricating oil in the needle roller bearing, improving lubrication conditions. A reduced number of needle rollers also results in a corresponding reduction in the number of cage pockets, which helps improve the structural strength of the cage.

[0032] In one embodiment, the ratio of the length of each needle along the axial direction of the planetary axis to the diameter of each needle is greater than or equal to 3.

[0033] In this embodiment, by controlling the lower limit of the ratio of the needle roller's axial length to its diameter, the length-to-diameter ratio of the needle roller can be increased, resulting in a more uniform force distribution on the needle roller. This helps reduce the risk of localized wear and improves the strength and reliability of the needle roller bearing. An increased length-to-diameter ratio leads to more pronounced line contact characteristics, increasing the proportion of rolling friction and decreasing the proportion of sliding friction, thereby reducing the overall frictional torque of the needle roller bearing.

[0034] In one embodiment, the planetary reducer includes two planetary gear sets, one of which transmits power output from the drive motor to the other planetary gear set.

[0035] In this system, the planet gears of one planetary gear set mesh with the sun gear of the drive motor shaft. Needle roller bearings are used to drive the planet gears of one planetary gear set.

[0036] In this embodiment, one planetary gear set receives power from the drive motor, and another planetary gear set receives power reduced by the speed of the first planetary gear set. Since the rotational speed of one planetary gear set is relatively high, the energy loss caused by the bearings in that planetary gear set accounts for more than 50% of the total energy loss caused by all bearings in the planetary reducer. This embodiment optimizes the dimensions of the needle roller bearing based on at least one of the following: the ratio of the needle roller diameter to the inner diameter of the planetary gears; the ratio of the product of the number of needle rollers and their diameter to the pitch circle circumference; or the ratio of the axial length of the needle roller to its diameter. Applying the optimized needle roller bearing to a planetary gear set reduces the frictional torque, thereby lowering the energy loss of the planetary gear set and improving the transmission efficiency of the planetary reducer.

[0037] In one embodiment, a planetary gear set includes a plurality of planetary gears surrounding the outer periphery of a motor shaft. Each planetary gear is used for transmission connection to at least one needle roller bearing.

[0038] In this embodiment, each planetary gear of a planetary gear set is connected to at least one needle roller bearing. Since the size of the needle roller bearing in this embodiment satisfies at least one of the following values: the ratio of the needle roller diameter to the inner diameter of the planetary gear, the ratio of the product of the number of needle rollers and the diameter to the pitch circle circumference, or the ratio of the axial length of the needle roller to the diameter, the frictional torque and reliability of the needle roller bearing can be taken into account. This is beneficial to reducing the mechanical loss caused by the bearing in a planetary gear set and improving the efficiency of power transmission of the planetary reducer.

[0039] Secondly, embodiments of this application provide a powertrain, which includes a drive motor and a planetary reducer as described in any embodiment of the first aspect, wherein the drive motor is used to drive the planetary reducer.

[0040] In the embodiments of this application, the planetary reducer in any embodiment of the first aspect is applied to the powertrain. Since the size of the needle roller bearing in the planetary reducer is optimized, the frictional torque of the needle roller bearing is reduced, which can improve the transmission efficiency of the powertrain without changing the powertrain layout.

[0041] Thirdly, embodiments of this application provide an electric vehicle, which includes a power battery and a powertrain, wherein the powertrain is used to receive power from the power battery and to drive the wheels of the electric vehicle.

[0042] In this embodiment, the second powertrain is applied to an electric vehicle. Since the frictional torque of the planetary reducer in the powertrain is reduced, it is beneficial to improve the transmission efficiency of the powertrain and enhance the working performance of the electric vehicle. Attached Figure Description

[0043] 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.

[0044] 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 and wheels provided in an embodiment of this application; Figure 3 This is a schematic diagram of the planetary reducer provided in the embodiments of this application; Figure 4 This is a cross-sectional view of the planetary reducer and drive motor provided in the embodiments of this application; Figure 5 This is a schematic diagram of the needle roller bearing provided in an embodiment of this application; Figure 6 This is a schematic diagram of the needle roller bearing provided in an embodiment of this application; Figure 7 This is a line graph showing the performance results of the needle roller bearing and planetary shaft provided in the embodiments of this application; Figure 8 This is a line graph showing the performance results of the needle roller bearing and planetary shaft provided in the embodiments of this application. Detailed Implementation

[0045] 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.

[0046] To reduce energy loss caused by bearings in a planetary reducer, this application provides a planetary reducer for driving a drive motor in an electric vehicle. The planetary gear set of the planetary reducer includes planetary gears and a planetary shaft. The planetary gears surround the outer circumference of the planetary shaft and drive the planetary shaft to rotate via needle roller bearings in the reducer. Multiple needle rollers of the needle roller bearing surround the inner circumference of the planetary gears and the outer circumference of the planetary shaft. The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is less than or equal to 0.183. This application, by adjusting the dimensional relationship between the needle roller bearings and the planetary gears, helps to reduce frictional losses in the needle roller bearings and improve the transmission efficiency of the planetary reducer. The planetary reducer provided in this application can be applied to powertrains and electric vehicles.

[0047] Please see Figure 1 , Figure 1 This is a schematic diagram of the electric vehicle 1 provided in an embodiment of this application.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Please see Figure 2 , Figure 2 This is a schematic diagram of the powertrain 10 and wheels 30 provided in an embodiment of this application. It should be noted that... Figure 2 This does not represent the specific structure, size, and positional relationship of the drive motor 200, planetary reducer 100, and motor controller 300.

[0052] The powertrain 10 of this embodiment includes a drive motor 200 and a planetary reducer 100. The drive motor 200 converts electrical energy into mechanical energy to generate driving torque. The planetary reducer 100 transmits the power output by the drive motor 200 to the wheels. The planetary reducer 100 can reduce the rotational speed of the power output by the drive motor 200, thereby increasing the output torque.

[0053] In one embodiment, the drive motor 200 includes a motor shaft, a motor rotor, and a motor stator. The motor shaft 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 to rotate.

[0054] In one embodiment, the powertrain 10 further includes a motor controller 300 for controlling at least one of the drive motor 200 and the planetary gearbox 100. In one embodiment, the motor controller 300 is used to convert between direct current (DC) and alternating current (AC). Exemplarily, the motor controller 300 can convert DC power supplied by a power battery into AC power and then transmit the AC power to the drive motor 200.

[0055] In one embodiment, the powertrain 10 also includes a differential, or the planetary reducer 100 of the powertrain 10 has a differential function. When the electric vehicle is turning or traveling on uneven surfaces, the differential or the planetary reducer 100 with a differential function can cause the wheels on different sides to rotate at different speeds.

[0056] The planetary reducer 100 of this application embodiment is described in detail below.

[0057] Please see Figures 3 to 5 , Figure 3 This is a schematic diagram of the planetary reducer 100 provided in an embodiment of this application. Figure 4 This is a cross-sectional view of the planetary reducer 100 and drive motor 200 provided in the embodiments of this application. Figure 5 This is a schematic diagram of the needle roller bearing 120 provided in the embodiments of this application.

[0058] Depending on the different architectures used, reducers can be divided into planetary reducers 100 and parallel shaft reducers. The planetary reducer 100 in this embodiment adopts an architecture in which the input and output ends are arranged coaxially. Compared with parallel shaft reducers, planetary reducers 100 have the advantages of compact structure and smaller radial dimensions.

[0059] The planetary gear set 110 of the planetary reducer 100 includes planetary gears 111 and a planetary shaft 112. The planetary gears 111 surround the outer periphery of the planetary shaft 112 and are used for transmission connection to the planetary shaft 112. In one embodiment, the planetary gear set 110 further includes a sun gear, a ring gear, and a planet carrier. The planetary gears 111 are used to mesh with at least one of the sun gear and the ring gear, and the planet carrier is transmissionally connected to the planetary gears 111 via the planetary shaft 112. One of the sun gear, planet carrier, and ring gear is an input end, and at least one of the sun gear, planet carrier, and ring gear is an output end. It should be noted that... Figure 3 This does not represent the actual structure, size, or positional relationship of the planetary gear set 110.

[0060] Bearings are crucial supporting components of the planetary reducer 100, supporting the rotational motion of the planetary gears 111 and planetary shaft 112, ensuring stable power transmission. The bearings, which are connected to the planetary gears 111 and planetary shaft 112, need to be installed between them, placing strict requirements on the radial space occupied by the bearings. In this embodiment, a needle roller bearing 120 is used to connect the planetary gears 111 and planetary shaft 112. Unlike ball bearings, the needle roller bearing 120 uses slender needles 121 as rolling elements, adapting to the limited installation space on the inner circumference of the planetary gears 111, thus meeting the miniaturization requirements of the planetary reducer 100. Furthermore, multiple needles 121 of the needle roller bearing 120 surround the inner circumference of the planetary gears 111 and the outer circumference of the planetary shaft 112, with line contact between the needles 121 and the planetary gears 111 and planetary shaft 112. This effectively withstands the radial force during planetary gear meshing, helping to prevent premature bearing failure.

[0061] Existing speed reducers typically focus on improving the strength and reliability of bearings. However, in planetary speed reducers 100, bearing friction losses are also a significant issue. The bearing losses in planetary speed reducers 100 are generally greater than those in parallel shaft speed reducers. Since the bearings continuously participate in the transmission process of the planetary speed reducer 100, friction losses increase with load and speed, making the frictional torque generated by the bearings one of the main sources of mechanical losses in the powertrain 10.

[0062] Please see Figure 6 , Figure 6 This is a schematic diagram of a needle roller bearing 120 provided in an embodiment of this application. The embodiment of this application reduces the frictional loss of the needle roller bearing 120 by adjusting at least one of parameters a, b, and c.

[0063] Parameter a is the ratio of the diameter d1 of each needle roller 121 in a single needle roller bearing 120 to the inner diameter of the planetary gear 111. The inner diameter of the planetary gear 111 can also be represented by the outer diameter d2 of the needle roller bearing 120.

[0064] Parameter 'a' reflects the dimensional relationship between the needle roller 121 and the planetary gear 111. By controlling the upper limit of parameter 'a', the needle roller 121 can be prevented from being too thick. If the diameter of the needle roller 121 is too large, the inertial force of the needle roller 121 and the contact area between the needle roller 121 and the planetary gear 111 or planetary shaft 112 will increase, which is not conducive to reducing the frictional torque of the needle roller bearing 120. An excessively large diameter of the needle roller 121 will also make it difficult for the needle roller bearing 120 to adapt to the narrow installation space between the planetary gear 111 and the planetary shaft 112. Furthermore, by controlling the lower limit of parameter 'a', insufficient load-bearing capacity of the needle roller bearing 120 due to the needle roller 121 being too thin can be avoided. The embodiments of this application adjust the lower and upper limits of parameter 'a' to balance the control of the frictional torque and reliability of the needle roller bearing 120.

[0065] Parameter b is the ratio of the product of the number of needle rollers 121 in a single needle roller bearing 120 and the diameter d1 of each needle roller 121 to the pitch circle circumference of the needle roller 121. The pitch circle circumference of the needle roller bearing 120 is the value obtained by multiplying the pitch circle diameter P of the needle roller bearing 120 by pi, representing the circumference of the imaginary circle formed by connecting the centers of all the needle rollers 121.

[0066] Parameter b reflects the arrangement density of the needle rollers 121. By controlling the upper limit of parameter b, a circumferential gap can be left between adjacent needle rollers 121 to avoid interference between different needle rollers 121. The reduction of parameter b can be achieved by adjusting the number and diameter of the needle rollers 121. By reducing at least one of the number or diameter of the needle rollers 121, it is beneficial to reduce the sliding friction caused by high-speed centrifugal force and reduce the frictional torque.

[0067] Parameter c is the ratio of the length l of each needle roller 121 along the axial direction of the planetary shaft 112 to the diameter d1 of each needle roller 121 in a single needle roller bearing 120. Parameter c reflects the relationship between the axial and radial lengths of the needle roller 121. By controlling the lower limit of parameter c, the length-to-diameter ratio of the needle roller 121 can be prevented from being too small, which is beneficial to improving the stability of the rotational motion of the needle roller 121 and reducing the risk of wear. In addition, increasing the length-to-diameter ratio of the needle roller 121 is beneficial to enhancing the load-bearing capacity and reliability of the needle roller bearing 120.

[0068] The different inner diameters of planetary gears 111 and the different adjustment ranges of the needle roller bearings 120 result in variations in the ranges of parameters a, b, and c. The specific ranges of parameters a, b, and c are described below when the inner diameter of planetary gears 111 is less than or equal to 25 mm.

[0069] In one embodiment, the inner diameter of planetary gear 111 is less than or equal to 25 mm. Parameter a is less than or equal to 0.18.

[0070] In this embodiment, parameter a is the ratio of the diameter of each needle roller 121 to the inner diameter of the planetary gear 111. By adjusting the upper limit of parameter a, the diameter of the needle roller 121 can be constrained, which helps to reduce the inertial force of the needle roller 121 and the contact area between the needle roller 121 and the raceway, thereby reducing the frictional torque.

[0071] In this embodiment, the value of parameter a also affects the installation difficulty of the needle roller bearing 120. The inner diameter of the planetary gear 111 is less than or equal to 25 mm, and the installation space on the inner circumference of the planetary gear 111 is limited. Setting an upper limit for parameter a allows the needle roller bearing 120 to adapt to the installation space on the inner circumference of the planetary gear 111, ensuring a reasonable arrangement space for the needle rollers 121, and balancing load-bearing capacity and smooth movement.

[0072] In one embodiment, the inner diameter of planetary gear 111 is less than or equal to 25 mm. Parameter a is greater than or equal to 0.165.

[0073] In this embodiment, the needle roller 121 serves as the load-bearing element of the needle roller bearing 120. If the diameter of the needle roller 121 is too small, its load-bearing capacity will be insufficient, making it difficult to meet the torque transmission requirements of the planetary gear 111. By adjusting the lower limit of parameter a, it is beneficial to ensure the strength of the needle roller bearing 120 and extend its service life.

[0074] In one embodiment, the inner diameter of planetary gear 111 is less than or equal to 25 mm. Parameter a is greater than or equal to 0.165, and parameter a is less than or equal to 0.18.

[0075] The embodiments of this application adjust the upper and lower limits of parameter a, which can reduce the frictional torque of needle roller bearing 120 by controlling the centrifugal force of needle roller 121, and improve the strength and reliability of needle roller bearing 120, thereby enhancing the overall performance of needle roller bearing 120.

[0076] In one embodiment, the inner diameter of planetary gear 111 is less than or equal to 25 mm. Parameter a is greater than or equal to 0.174, and parameter a is less than or equal to 0.178.

[0077] In the embodiments of this application, by narrowing the range of parameter a from 0.165 to 0.18 to 0.174 to 0.178, it is beneficial to balance the effects of reducing frictional torque and improving reliability.

[0078] In addition to contacting the planetary gears 111, the needle rollers 121 are also connected to the cage 122 and the planetary shaft 112. Specifically, the cage 122 is used to mount and separate multiple needle rollers 121, which are fitted onto the planetary shaft 112. Since parameter a relates to the diameter of the needle rollers 121, adjusting parameter a will also affect the performance of the cage 122 and the planetary shaft 112.

[0079] In one embodiment, the inner diameter of the planetary gear 111 is less than or equal to 25 mm. Parameter a is less than or equal to 0.18. The safety factor of at least one of the cage 122 and the planetary shaft 112 is greater than 1.

[0080] In this embodiment, both the needle roller 121 and the planetary shaft 112 are located on the inner circumference of the planetary gear 111. If parameter a is too large, it indicates that the needle roller 121 occupies a large space on the inner circumference of the planetary gear 111, resulting in a need to shorten the diameter of the planetary shaft 112 to meet the installation requirements of the needle roller bearing 120. However, if the diameter of the planetary shaft 112 is too small, it will lead to insufficient strength of the planetary shaft 112 itself. This embodiment, by adjusting the upper limit of parameter a, helps to enhance the bending resistance of the planetary shaft 112 and improve the safety factor of the planetary shaft 112.

[0081] In this embodiment, if parameter a is too large, the gap between the needle roller 121 and the cage 122 will decrease due to the increase in the diameter of the needle roller 121, increasing the centrifugal force of the needle roller 121 and leading to accelerated wear on both the needle roller 121 and the cage 122. This embodiment, by adjusting the upper limit of parameter a, helps alleviate the wear of the cage 122 and improves its safety factor.

[0082] In one embodiment, the inner diameter of the planetary gear 111 is less than or equal to 25 mm. Parameter a is greater than or equal to 0.165 and less than or equal to 0.18, and the safety factor of the cage 122 is greater than or equal to 1.

[0083] In this embodiment, the cage 122 has multiple pockets for accommodating needle rollers 121, and the number of pockets in the cage 122 is related to the number of needle rollers 121. By adjusting the lower limit of parameter a (which is less than or equal to 0.18), an excessive number of needle rollers 121 can be avoided, which helps to reduce the number of pockets and improve the structural strength of the cage 122.

[0084] In one embodiment, the inner diameter of the planetary gear 111 is less than or equal to 25 mm. Parameter a is greater than or equal to 0.174 and less than or equal to 0.178, and the safety factor of each of the cage 122 and the planetary shaft 112 is greater than 1.

[0085] In this embodiment, parameter a is between 0.165 and 0.18, which meets the requirements for improving the frictional torque and reliability of the needle roller bearing 120. Furthermore, adjusting parameter a to the range of 0.174 to 0.178 helps to balance the safety performance of the cage 122 and the planetary shaft 112.

[0086] In one embodiment, the inner diameter of planetary gear 111 is less than or equal to 25 mm. Parameter b is less than or equal to 0.7.

[0087] In this embodiment, parameter b is the ratio of the product of the number of needle rollers 121 and the diameter of each needle roller 121 to the pitch circle circumference of the needle roller 121. By controlling the upper limit of parameter b, the number of needle rollers 121 can be constrained. Reducing the number of needle rollers 121 allows for sufficient circumferential clearance between adjacent needle rollers 121, preventing interference between different needle rollers 121. Increased circumferential clearance between adjacent needle rollers 121 also facilitates the flow of lubricating oil in the needle roller bearing 120, improving lubrication conditions. A reduction in the number of needle rollers 121 results in a corresponding reduction in the number of pockets in the cage 122, which helps improve the structural strength of the cage 122.

[0088] In one embodiment, the inner diameter of planetary gear 111 is less than or equal to 25 mm. Parameter b is less than or equal to 0.7, and parameter a is less than or equal to 0.18.

[0089] In this embodiment, the value range of parameter b can limit the number of needle rollers 121. Theoretically, reducing the number of needle rollers 121 can increase their diameter. However, an excessively large diameter of the needle rollers 121 increases the difficulty of reducing frictional torque. This embodiment adjusts the lower limits of parameter b and parameter a, using parameter a to control the diameter of the needle rollers 121. This reduces the arrangement density of the needle rollers 121 while lowering the frictional torque of the needle roller bearing 120, which is beneficial for improving the reliability of the needle roller bearing 120 and the transmission efficiency of the planetary reducer 100.

[0090] In one embodiment, the inner diameter of planetary gear 111 is less than or equal to 25 mm. Parameter c is greater than or equal to 3.

[0091] In this embodiment, parameter c is the ratio of the axial length to the radial length of the needle roller 121. By controlling the lower limit of parameter c, increasing the length-to-diameter ratio of the needle roller 121 can make the force distribution of the needle roller 121 more uniform, which helps to reduce the risk of local wear of the needle roller 121 and improve the strength and reliability of the needle roller bearing 120. With an increased length-to-diameter ratio, the line contact characteristics of the needle roller 121 are more pronounced, the proportion of rolling friction increases, and the proportion of sliding friction decreases, thereby reducing the total frictional torque of the needle roller bearing 120.

[0092] In one embodiment, the inner diameter of planetary gear 111 is less than or equal to 25 mm. Parameter c is greater than or equal to 3, and parameter a is greater than or equal to 0.165.

[0093] In this embodiment, the value of parameter c can be increased by at least one of the following two methods: increasing the axial length of needle roller 121 or decreasing the diameter of needle roller 121. However, if the diameter of needle roller 121 is too small, it will adversely affect the load-bearing capacity of needle roller 121. This embodiment adjusts the lower limit of parameter c and the upper limit of parameter a, and uses parameter a to control the diameter of needle roller 121. This can reduce the frictional torque of needle roller bearing 120 while increasing the load-bearing capacity of needle roller 121, thereby improving the transmission efficiency of planetary reducer 100 and powertrain 10.

[0094] In one embodiment, the planetary reducer 100 includes two planetary gear sets 110, denoted as planetary gear set 110a and planetary gear set 110b. Planetary gear set 110a transmits power output from the drive motor 200 to planetary gear set 110b. The planet gears 111 of planetary gear set 110a mesh with the sun gear of the motor shaft 210. Needle roller bearings 120 are used to drive the planet gears 111 of planetary gear set 110a.

[0095] In this embodiment, planetary gear set 110a receives power transmitted from drive motor 200, and planetary gear set 110b receives power reduced by planetary gear set 110a. Since the rotational speed of planetary gear set 110a is relatively high, the energy loss caused by the bearings of planetary gear set 110a accounts for more than 50% of the total energy loss caused by all bearings in planetary reducer 100. This embodiment optimizes the dimensions of needle roller bearing 120 based on at least one of parameters a, b, or c. Applying the optimized needle roller bearing 120 to planetary gear set 110a reduces the frictional torque of the needle roller bearing 120, thereby reducing energy loss in planetary gear set 110a and improving the transmission efficiency of planetary reducer 100.

[0096] In one embodiment, the planetary gear set 110a includes a plurality of planetary gears 111 surrounding the outer periphery of the motor shaft 210. Each planetary gear 111 is used for transmission connection to at least one needle roller bearing 120.

[0097] In this embodiment of the application, each planetary gear 111 of the planetary gear set 110a is connected to at least one needle roller bearing 120 for transmission. Since the size of the needle roller bearing 120 in this embodiment of the application meets the numerical range of at least one of parameter a, parameter b or parameter c, the frictional torque and reliability of the needle roller bearing 120 can be taken into account, which is beneficial to reduce the mechanical loss caused by the bearing in the planetary gear set 110a and improve the efficiency of power transmission of the planetary reducer 100.

[0098] When the inner diameter of planetary gear 111 in planetary gear set 110a is less than or equal to 25 mm, parameter b, life ratio, cage safety factor, planetary shaft safety factor, and friction index are analyzed according to the following Examples 1-4 and Comparative Examples 1-10: Examples 1-4: Parameter a is 0.165, 0.17, 0.174, and 0.178 respectively.

[0099] Comparative Examples 1-10: The parameter a is 0.13, 0.135, 0.139, 0.143, 0.148, 0.152, 0.157, 0.161, 0.183, and 0.187 respectively.

[0100] In this context, the life ratio of the above embodiments and comparative examples refers to the ratio of the lifespan of the needle roller bearing relative to that of Embodiment 3. The cage safety factor is the ratio of the fatigue limit stress of the cage to the working stress. The planetary shaft safety factor is the ratio of the fatigue limit stress of the planetary shaft to the working stress. The friction index is a proportionalized index of the theoretically calculated friction torque of the needle roller bearing, which can be used to compare the energy losses of different needle roller bearings.

[0101] The relevant performance results are shown in Table 1 and Figure 7 As shown, Figure 7 This is a line graph showing the performance results of the needle roller bearing 120 and planetary shaft 112 provided in the embodiments of this application.

[0102] Table 1 Performance results of needle roller bearings and planetary shafts

[0103] Please refer to Table 1 and... Figure 7 .

[0104] Comparing Examples 1-4 with Comparative Examples 1-6, when parameter a is in the range of 0.13 to 0.152, the diameter of the needle roller 121 is too small, the number of needle rollers 121 increases, which increases the number of pockets in the cage 122, thus making it difficult for the safety factor of the cage 122 to meet the usage requirements.

[0105] Comparing Examples 1-4 with Comparative Examples 1-8, when parameter a is in the range of 0.13 to 0.161, the diameter of the needle roller 121 is too small, which negatively affects the load-bearing capacity and is not conducive to improving the service life of the needle roller bearing 120.

[0106] Comparing Examples 1-4 with Comparative Examples 9-10, when parameter a is in the range of 0.183 to 0.187, due to the larger diameter of the needle roller 121, the needle roller bearing 120 occupies a larger space on the inner circumference of the planetary gear 111, which is equivalent to borrowing part of the installation space of the planetary shaft 112. The diameter of the planetary shaft 112 needs to be reduced, which negatively affects the structural strength of the planetary shaft 112.

[0107] When the inner diameter of planetary gear 111 is less than or equal to 25 mm, the present application embodiment controls parameter a within the range of 0.165 to 0.178, which can reduce the frictional torque of needle roller bearing 120 while ensuring the safety performance of needle roller bearing 120 and planetary shaft 112.

[0108] The following describes the specific ranges of parameters a, b, and c when the inner diameter of planetary gear 111 is greater than 25 mm and less than or equal to 35 mm.

[0109] In one embodiment, the inner diameter of planetary gear 111 is greater than 25 mm and less than or equal to 35 mm. Parameter a is less than or equal to 0.183.

[0110] In this embodiment, when the planetary reducer 100 uses a planetary gear 111 with a relatively large inner diameter, the installation space on the inner circumference of the planetary gear 111 increases, allowing for a wider adjustment range of the needle roller 121 diameter. A larger inner diameter of the planetary gear 111 also directly affects the value of parameter a. Setting the upper limit of parameter a to 0.183 helps reduce the inertial force of the needle roller 121 and the contact area between the needle roller 121 and the raceway, thus reducing frictional torque. With an increased inner diameter of the planetary gear 111, the diameter of the needle roller 121 can be appropriately increased, improving the utilization rate of the space on the inner circumference of the planetary gear 111 and enhancing the structural strength of the needle roller bearing 120.

[0111] In one embodiment, the inner diameter of planetary gear 111 is greater than 25 mm and less than or equal to 35 mm. Parameter a is greater than or equal to 0.157.

[0112] In this embodiment, adjusting the lower limit of parameter a helps to improve the load-bearing capacity of the needle roller bearing 120 and extend its service life. Setting the lower limit of parameter a to 0.157 takes into account the direct impact of a larger inner diameter of the planetary gear 111 on parameter a.

[0113] In one embodiment, the inner diameter of planetary gear 111 is greater than 25 mm and less than or equal to 35 mm. Parameter a is greater than or equal to 0.157 and parameter a is less than or equal to 0.183.

[0114] The embodiments of this application adjust the upper and lower limits of parameter a, which can reduce the frictional torque of needle roller bearing 120 by controlling the centrifugal force of needle roller 121, and improve the strength and reliability of needle roller bearing 120, thereby enhancing the overall performance of needle roller bearing 120.

[0115] In one embodiment, the inner diameter of planetary gear 111 is greater than 25 mm and less than or equal to 35 mm. Parameter a is greater than or equal to 0.165 and parameter a is less than or equal to 0.174.

[0116] In this embodiment of the application, considering the influence of the large inner diameter of the planetary gear 111 on parameter a, the range of parameter a is narrowed from 0.157 to 0.183 to 0.165 to 0.174, which is beneficial to reduce the frictional torque of the needle roller bearing 120 and improve the reliability of the needle roller bearing 120.

[0117] In one embodiment, the inner diameter of the planetary gear 111 is greater than 25 mm and less than or equal to 35 mm. Parameter a is less than or equal to 0.183. The safety factor of each of the cage 122 and the planetary shaft 112 is greater than or equal to 1.

[0118] In this embodiment, the planetary gear 111 surrounds the outer periphery of the needle roller 121 and the planetary shaft 112. The larger inner diameter of the planetary gear 111 increases the mounting space provided by the inner periphery of the planetary gear 111 for the planetary shaft 112. By controlling the upper limit of parameter a, the diameter of the needle roller 121 can be prevented from becoming too large, allowing for an increase in the diameter of the planetary shaft 112, which is beneficial for enhancing the structural strength of the planetary shaft 112.

[0119] In this embodiment, if parameter a is too large, the gap between the needle roller 121 and the cage 122 will decrease due to the increase in the diameter of the needle roller 121, increasing the centrifugal force of the needle roller 121 and leading to accelerated wear on both the needle roller 121 and the cage 122. This embodiment, by adjusting the upper limit of parameter a, helps alleviate the wear of the cage 122 and improves its safety factor.

[0120] In one embodiment, the inner diameter of the planetary gear 111 is greater than 25 mm and less than or equal to 35 mm. Parameter a is greater than or equal to 0.157 and less than or equal to 0.183, and the safety factor of the cage 122 is greater than 1.

[0121] In this embodiment, the number of pockets in the cage 122 is related to the number of needle rollers 121. Controlling the number of pockets helps improve the structural strength of the cage 122. The number of needle rollers 121 is affected by their diameter and the inner diameter of the planetary gear 111. When the planetary reducer 100 uses planetary gears 111 with larger inner diameters, the space on the inner circumference of the planetary gear 111 for accommodating the needle roller bearing 120 increases, theoretically allowing for an increase in the number of needle rollers 121. However, too many needle rollers 121 will lead to an increase in pockets, impairing the structural strength of the needle roller bearing 120. When parameter a is less than or equal to 0.183, adjusting the lower limit of parameter a can prevent an excessive number of needle rollers 121, thus reducing the number of pockets and improving the structural strength of the cage 122.

[0122] In one embodiment, the inner diameter of the planetary gear 111 is greater than 25 mm and less than or equal to 35 mm. Parameter a is greater than or equal to 0.165 and less than or equal to 0.174, and the safety factor of each of the cage 122 and the planetary shaft 112 is greater than or equal to 1.

[0123] In this embodiment, parameter a is between 0.157 and 0.183, which meets the requirements for improving the frictional torque and reliability of the needle roller bearing 120. Furthermore, adjusting parameter a to the range of 0.165 to 0.174 helps to balance the safety performance of the cage 122 and the planetary shaft 112.

[0124] In one embodiment, the inner diameter of planetary gear 111 is greater than 25 mm and less than or equal to 35 mm. Parameter b is less than or equal to 0.67.

[0125] In this embodiment, parameter b is related to the number and diameter of the needle rollers 121 and the pitch circle circumference of the needle roller bearing 120. By controlling the upper limit of parameter b, the number of needle rollers 121 can be constrained. Reducing the number of needle rollers 121 allows for sufficient circumferential clearance between adjacent needle rollers 121, preventing interference between different needle rollers 121. Increased circumferential clearance between adjacent needle rollers 121 also facilitates the flow of lubricating oil in the needle roller bearing 120, improving lubrication conditions. A reduction in the number of needle rollers 121 results in a corresponding reduction in the number of pockets in the cage 122, which helps improve the structural strength of the cage 122.

[0126] In this embodiment, when the planetary reducer 100 uses planetary gears 111 with a larger inner diameter, the inner and outer diameters of the needle roller bearing 120 also have room for improvement. The pitch circle circumference of the needle roller bearing 120 is related to its inner and outer diameters. In this embodiment, the upper limit of parameter b is set to 0.67, which allows the pitch circle circumference of the needle roller bearing 120 to be adjusted according to actual needs without increasing the frictional torque or affecting the bearing reliability.

[0127] In one embodiment, the inner diameter of planetary gear 111 is greater than 25 mm and less than or equal to 35 mm. Parameter c is greater than or equal to 3.

[0128] In this embodiment, parameter c represents the length-to-diameter ratio of the needle roller 121. By controlling the lower limit of parameter c, increasing the length-to-diameter ratio of the needle roller 121 can make the force distribution of the needle roller 121 more uniform, which helps to reduce the risk of local wear of the needle roller 121 and improve the strength and reliability of the needle roller bearing 120. With an increased length-to-diameter ratio of the needle roller 121, the line contact characteristics of the needle roller 121 are more pronounced, the proportion of rolling friction increases, and the proportion of sliding friction decreases, thereby reducing the total frictional torque of the needle roller bearing 120.

[0129] When the inner diameter of planetary gear 111 in planetary gear set 110a is greater than 25 mm and less than or equal to 35 mm, the following examples 5-11 and comparative examples 11-18 are used to analyze parameter b, life ratio, cage safety factor, planetary shaft safety factor, and friction index: Examples 5-11: The parameter a is 0.157, 0.161, 0.165, 0.17, 0.174, 0.178, and 0.183 respectively.

[0130] Comparative Examples 11-18: The parameter a is 0.135, 0.139, 0.143, 0.148, 0.152, 0.187, 0.191, and 0.196 respectively.

[0131] In this context, the lifespan ratio of the above embodiments and comparative examples refers to the ratio of the lifespan of the needle roller bearing relative to that of Embodiment 9.

[0132] The relevant performance results are shown in Table 2 and Figure 8 As shown, Figure 8 This is a line graph showing the performance results of the needle roller bearing 120 and planetary shaft 112 provided in the embodiments of this application.

[0133] Table 2 Performance results of needle roller bearings and planetary shafts

[0134] Please refer to Table 2 and... Figure 8 .

[0135] Comparing Examples 5-11 with Comparative Examples 11-15, when parameter a is in the range of 0.135 to 0.152, the diameter of the needle roller 121 is too small, the number of needle rollers 121 increases, which increases the number of pockets in the cage 122, thus making it difficult for the safety factor of the cage 122 to meet the usage requirements.

[0136] Comparing Examples 5-11 with Comparative Examples 11-15, when parameter a is in the range of 0.135 to 0.152, the diameter of the needle roller 121 is too small, which negatively affects the load-bearing capacity and is not conducive to improving the service life of the needle roller bearing 120.

[0137] Comparing Examples 5-11 with Comparative Examples 16-18, when parameter a is in the range of 0.187 to 0.196, due to the larger diameter of the needle roller 121, the needle roller bearing 120 occupies a larger space on the inner circumference of the planetary gear 111, which is equivalent to borrowing part of the installation space of the planetary shaft 112. The diameter of the planetary shaft 112 needs to be reduced, which negatively affects the structural strength of the planetary shaft 112.

[0138] When the inner diameter of the planetary gear 111 is greater than 25 mm and less than or equal to 35 mm, the present application embodiment controls parameter a within the range of 0.157 to 0.183, which can reduce the frictional torque of the needle roller bearing 120 while ensuring the safety performance of the needle roller bearing 120 and the planetary shaft 112.

[0139] The planetary reducer, 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 methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in specific embodiments and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A planetary reducer, characterized in that, The planetary reducer is used to drive the drive motor of an electric vehicle. The planetary gear set of the planetary reducer includes planetary gears and a planetary shaft. The planetary gears drive the planetary shaft to rotate via needle roller bearings in the planetary reducer. Multiple needle rollers of the needle roller bearings are arranged around the inner circumference of the planetary gears and the outer circumference of the planetary shaft, wherein: The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is less than or equal to 0.

183.

2. The planetary reducer according to claim 1, characterized in that, The inner diameter of the planetary gear is less than or equal to 25 mm, wherein: The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is less than or equal to 0.

18.

3. The planetary reducer according to claim 2, characterized in that, The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is greater than or equal to 0.

165.

4. The planetary reducer according to claim 2 or 3, characterized in that, The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is greater than or equal to 0.174, and the ratio of the diameter of each needle roller to the inner diameter of the planetary gear is less than or equal to 0.

178.

5. The planetary reducer according to any one of claims 2-4, characterized in that, The cage of the needle roller bearing is used to mount and separate the plurality of needle rollers, and the safety factor of at least one of the cage and the planetary shaft is greater than 1.

6. The planetary reducer according to claim 1, characterized in that, The inner diameter of the planetary gear is greater than 25 mm, and the inner diameter of the planetary gear is less than or equal to 35 mm, wherein: The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is greater than or equal to 0.

157.

7. The planetary reducer according to claim 6, characterized in that, The ratio of the diameter of each needle roller to the inner diameter of the planetary gear is greater than or equal to 0.165, and the ratio of the diameter of each needle roller to the inner diameter of the planetary gear is less than or equal to 0.

174.

8. The planetary reducer according to claim 6 or 7, characterized in that, The cage of the needle roller bearing is used to mount and separate the plurality of needle rollers, and the safety factor of each of the cage and the planetary shaft is greater than or equal to 1.

9. The planetary reducer according to any one of claims 1-8, characterized in that, The ratio of the product of the number of needle rollers and the diameter of each needle roller to the pitch circle circumference of the needle roller bearing is less than or equal to 0.

7.

10. The planetary reducer according to any one of claims 1-8, characterized in that, The ratio of the product of the number of needle rollers and the diameter of each needle roller to the pitch circle circumference of the needle roller bearing is less than or equal to 0.

67.

11. The planetary reducer according to any one of claims 1-10, characterized in that, The ratio of the length of each needle along the axial direction of the planetary axis to the diameter of each needle is greater than or equal to 3.

12. The planetary reducer according to any one of claims 1-11, characterized in that, The planetary reducer includes two planetary gear sets, one planetary gear set being used to transmit the power output from the drive motor to the other planetary gear set, wherein: The planetary gears of the planetary gear set are used to mesh with the sun gear of the motor shaft of the drive motor, and the needle roller bearing is used to drive the planetary gears of the planetary gear set.

13. The planetary reducer according to claim 12, characterized in that, The planetary gear set includes a plurality of planetary gears, which surround the outer periphery of the motor shaft, and each planetary gear is used for transmission connection to at least one needle roller bearing.

14. A powertrain, characterized in that, The powertrain includes a drive motor and a planetary gearbox as described in any one of claims 1-13, wherein the drive motor is used to drive the planetary gearbox.

15. An electric vehicle, characterized in that, The electric vehicle includes a power battery and a powertrain as described in claim 14, the powertrain being used to receive power from the power battery and to drive the wheels of the electric vehicle.

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