Power assembly and electric vehicle

Abstract

The utility model provides a power assembly and an electric vehicle. The power assembly comprises a speed reducer and a driving motor. A gear set of the speed reducer comprises an input wheel, a middle large gear, a middle small gear and an output wheel. The input wheel is used for receiving driving rotation of the driving motor. The middle large gear is used for being meshed with the input wheel and driving the middle small gear to rotate synchronously. An output wheel is for engaging with the intermediate pinion and for driving a wheel. Wherein the reduction ratio of meshing of the input wheel and the middle large gear is u1, the reduction ratio of meshing of the middle small gear and the output wheel is u2, and 1.2 < = u2: u1 < = 1.3. According to the power assembly provided by the invention, the NVH performance is improved by optimally distributing the parameters of the gear set in the speed reducer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicles, in particular to a power assembly and an electric vehicle. BACKGROUND

[0002] The electric vehicle has higher requirements for the vehicle NVH performance because of the absence of engine bottom noise. As the main excitation source of the electric vehicle NVH noise, the power assembly needs to reasonably optimize the reducer in the power assembly to reduce the noise excitation of the reducer and improve the vehicle NVH performance. CONTENT OF THE UTILITY MODEL

[0003] The present application provides a power assembly and an electric vehicle, which improves the NVH performance by optimizing the parameters of the gear set in the reducer.

[0004] In a first aspect, the present application provides a power assembly, which comprises a reducer and a drive motor. The gear set of the reducer comprises an input wheel, an intermediate large gear, an intermediate small gear and an output wheel. The input wheel is used to receive the driving rotation of the drive motor. The intermediate large gear is used to mesh with the input wheel and drive the intermediate small gear to rotate synchronously. The output wheel is used to mesh with the intermediate small gear and drive the wheel. The reduction ratio of the input wheel meshing with the intermediate large gear is u1, and the reduction ratio of the intermediate small gear meshing with the output wheel is u2, and 1.2≤u2:u1≤1.3.

[0005] The power assembly provided by the present application drives the drive motor and the wheel through the gear set. The meshing transmission of the input wheel and the intermediate large gear and the meshing transmission of the intermediate small gear and the output wheel achieve the effect of reducing the rotation speed and improving the torque. Thus, the input wheel and the intermediate large gear cooperate to form the first-stage transmission of the reducer, and the intermediate small gear and the output wheel cooperate to form the second-stage transmission of the reducer. The power assembly provided by the present application also distributes the reduction ratios of the first-stage transmission and the second-stage transmission. On the premise of satisfying the speed reduction and torque increase of the reducer, the power assembly avoids the phenomenon that the bearing rotation speed of the transmission shaft for bearing the intermediate small gear is too high to exceed the bearing carrying limit because the reduction ratio of the second-stage transmission is too large, and also avoids the phenomenon that the transmission shaft amplitude deflection is large and the noise is out of limit because the torque of the transmission shaft for bearing the intermediate small gear is too large due to the too small reduction ratio of the second-stage transmission.

[0006] The power assembly provided by the present application reasonably distributes the reduction ratios between the first-stage transmission and the second-stage transmission. On the premise of satisfying the speed reduction and torque increase of the reducer, the power assembly takes into account the bearing carrying capacity and the torque size borne by the transmission shaft, so that the working conditions of the gear set of the reducer are relatively balanced to improve the NVH performance.

[0007] One implementation, the speed reducer comprises an intermediate shaft, a middle section of the intermediate shaft is used to fix an intermediate large gear and an intermediate small gear, two ends of the intermediate shaft are respectively used to fix an inner ring of a tapered bearing, and outer rings of the two tapered bearings are respectively fixed on a housing of the speed reducer.

[0008] In the implementation, the intermediate large gear and the intermediate small gear are coaxially fixed by the intermediate shaft. The intermediate shaft is rotatably connected to the housing of the speed reducer by the two tapered bearings. Because the intermediate large gear and the intermediate small gear are respectively engaged with the input gear and the output gear, axial components and resultant forces generated by the intermediate large gear and the intermediate small gear during engagement will drive the intermediate shaft to move along the axial direction of the intermediate shaft. The two tapered bearings can respectively form axial thrusts on the intermediate shaft at the two ends of the intermediate shaft to reduce the axial movement of the intermediate shaft, thereby reducing the noise generated by the speed reducer due to the axial movement of the intermediate shaft and improving the NVH performance of the power assembly.

[0009] One implementation, the intermediate large gear and the intermediate small gear are both helical gears, the intermediate large gear and the intermediate small gear have the same helical direction, and the helical angle of the intermediate large gear is greater than the helical angle of the intermediate small gear.

[0010] In the implementation, the helical gears have stronger bearing capacity and can meet the torque transmission requirements of the speed reducer. Because the intermediate large gear and the intermediate small gear are coaxially driven, the intermediate large gear and the intermediate small gear have the same helical direction. The helical direction of the intermediate large gear is opposite to the helical direction of the input gear, and the helical direction of the intermediate small gear is opposite to the helical direction of the output gear. During the operation of the speed reducer, the input gear and the output gear will generate axial forces in opposite directions on the intermediate gear set, and then generate axial forces in opposite directions on the intermediate shaft used to fix the intermediate large gear and the intermediate small gear.

[0011] The torque of the intermediate large gear in the speed reducer is small, and the torque of the intermediate small gear is large. The helical angle of the intermediate large gear is large, which is conducive to making the axial component of the force generated when the intermediate large gear is engaged with the input gear for transmission larger. The helical angle of the intermediate small gear is small, which is conducive to making the axial component of the force generated when the intermediate small gear is engaged with the output gear for transmission smaller. Thus, the sizes of the axial forces in opposite directions received by the intermediate large gear and the intermediate small gear are less different. When the intermediate small gear and the intermediate large gear transmit the axial forces to the intermediate shaft, most of the axial forces received by the intermediate shaft can be counteracted, so that the intermediate shaft and the tapered bearings at the two ends of the intermediate shaft as a whole receive smaller axial forces, the stress of the power assembly is more balanced, and the NVH performance of the power assembly is improved.

[0012] The helix angle of the intermediate gear wheel meshing with the input wheel is larger, which can meet the transmission demand of high speed of the input wheel. After the input wheel transmits power to the intermediate gear wheel, the rotation speed of the intermediate shaft and the intermediate pinion is reduced. The helix angle of the intermediate pinion meshing with the output wheel is smaller, which is also enough to meet the transmission demand of lower rotation speed of the intermediate pinion.

[0013] In an implementation, the helix angle of the intermediate gear wheel is greater than or equal to 26° and less than or equal to 30°, and the helix angle of the intermediate pinion is greater than or equal to 20° and less than or equal to 24°.

[0014] In the implementation, the helix angles of the intermediate gear wheel and the intermediate pinion are matched with the speed reduction ratio distribution of the first-stage transmission and the second-stage transmission, which can offset the axial forces of the input wheel on the intermediate gear wheel and the output wheel on the intermediate pinion, so that the axial forces on the intermediate shaft and the tapered bearings at both ends are smaller, and the stress of the power assembly is more balanced, which is beneficial to improve the NVH performance of the power assembly.

[0015] In an implementation, the helix angle of the intermediate gear wheel is 28°, and the helix angle of the intermediate pinion is 21.8°.

[0016] In an implementation, the helix directions of the intermediate gear wheel and the intermediate pinion are both right-handed.

[0017] In an implementation, along the axial direction of the motor shaft of the driving motor, the intermediate pinion, the intermediate gear wheel and the motor rotor of the driving motor are arranged in sequence, and the effective meshing width of the intermediate gear wheel and the input wheel is smaller than the effective meshing width of the intermediate pinion and the output wheel.

[0018] In the implementation, the driving motor serves as a power source, and the intermediate gear wheel is closer to the rotor of the driving motor than the intermediate pinion, i.e., the first-stage transmission in the reducer is closer to the driving motor than the second-stage transmission, which is more reasonable and is beneficial to miniaturization of the power assembly. The second-stage transmission transmits larger torque, and the effective meshing width of the second-stage transmission is set to be larger to better adapt to the torque transmitted between the intermediate pinion and the output wheel.

[0019] In an implementation, the effective meshing width of the intermediate gear wheel and the input wheel is greater than or equal to 40 mm and less than or equal to 43 mm, and the effective meshing width of the intermediate pinion and the output wheel is greater than or equal to 46 mm and less than or equal to 50 mm.

[0020] In the implementation, the effective meshing width distribution of the first-stage transmission and the second-stage transmission is matched with the speed reduction ratio distribution of the first-stage transmission and the second-stage transmission, which can meet the torque transmission demand of the second-stage transmission and ensure reliable work of the power assembly.

[0021] In an implementation, the tooth width of the intermediate large gear is 41 mm, and the tooth width of the intermediate small gear is 50 mm.

[0022] In the implementation, the sum of the tooth widths of the intermediate large gear and the intermediate small gear is limited by the axial length of the intermediate shaft. Reasonable allocation of the tooth widths of the intermediate large gear and the intermediate small gear can meet the transmission requirement of the intermediate small gear for large torque and take into account the machinability of the intermediate large gear and the intermediate small gear.

[0023] In an implementation, the tooth width of the input wheel is 44 mm, and the tooth width of the output wheel is 47 mm.

[0024] In the implementation, the tooth width of the input wheel and the tooth width of the output wheel are matched with the tooth width of the intermediate large gear and the tooth width of the intermediate small gear respectively. The input wheel, as the driving wheel of the first-stage transmission, has a wider tooth width than the tooth width of the intermediate large gear, as the driven wheel in the first-stage transmission, so that the full size of the intermediate large gear along the axial direction of the intermediate shaft can be ensured to be engaged with the input wheel when the intermediate shaft has axial movement, thereby improving the torque transmission capacity of the first-stage transmission. Correspondingly, the intermediate small gear, as the driving wheel of the second-stage transmission, has a wider tooth width than the tooth width of the output wheel, as the driven wheel in the second-stage transmission, so that the full size of the output wheel along the axial direction of the intermediate shaft can be ensured to be engaged with the intermediate small gear when the intermediate shaft has axial movement, thereby improving the torque transmission capacity of the second-stage transmission.

[0025] In an implementation, the effective engagement width of the intermediate large gear and the input wheel is equal to 41 mm, and the effective engagement width of the intermediate small gear and the output wheel is equal to 47 mm.

[0026] In an implementation, the normal module of the intermediate large gear is less than the normal module of the intermediate small gear.

[0027] In the implementation, because the rotation speed of the first-stage transmission is high, controlling the normal module of the first-stage transmission to be small is beneficial to reduce the noise of the engagement transmission between the input wheel and the intermediate large gear. Because the torque of the second-stage transmission is large, controlling the normal module of the second-stage transmission to be large is beneficial to improve the torque bearing capacity of the second-stage transmission.

[0028] In an implementation, the normal module of the intermediate large gear is greater than or equal to 1.48 and less than or equal to 1.55, and the normal module of the intermediate small gear is greater than or equal to 2.55 and less than or equal to 2.75.

[0029] In the present implementation, the normal modulus of the intermediate gear wheel is greater than or equal to 1.48, so that the meshing teeth of the intermediate gear wheel and the input wheel have a certain tooth thickness, avoiding tooth tip hardening after heat treatment of the intermediate gear wheel or the input wheel, which leads to shortened service life of the tooth tip and poor NVH performance due to damage to the tooth tip. The normal modulus of the intermediate gear wheel is less than or equal to 1.55, which can reduce the noise generated when the input wheel meshes with the intermediate gear wheel.

[0030] The normal modulus of the intermediate pinion is greater than or equal to 2.55, which ensures reliable meshing and torque transmission between the intermediate pinion and the output wheel. The normal modulus of the intermediate pinion is less than or equal to 2.75, which can improve the machinability of the intermediate pinion and the output wheel, respectively.

[0031] In an implementation, the normal modulus of the intermediate gear wheel is equal to 1.518, and the normal modulus of the intermediate pinion is equal to 2.615.

[0032] In an implementation, the normal pressure angle of the intermediate gear wheel is less than the normal pressure angle of the intermediate pinion.

[0033] In the present implementation, the load on the output wheel in the reducer is large, so that the intermediate pinion receives a large radial component force when drivingly connecting the output wheel. Increasing the normal pressure angle of the intermediate pinion makes the load capacity of the intermediate pinion stronger. The load on the input wheel is small, and setting the normal pressure angle of the intermediate gear wheel to be small can also meet the load demand of the input wheel.

[0034] The normal pressure angle of the intermediate pinion is greater than the normal pressure angle of the intermediate gear wheel, which can make the resultant force of the radial force of the input wheel acting on the intermediate gear wheel and the radial force of the output wheel acting on the intermediate pinion smaller, so that the tapered bearings fixed at both ends of the intermediate shaft can bear smaller radial component forces, and the stress of the power assembly is more balanced, improving the NVH performance.

[0035] In an implementation, the normal pressure angle of the intermediate gear wheel is greater than or equal to 15° and less than or equal to 18°, and the normal pressure angle of the intermediate pinion is greater than or equal to 20° and less than or equal to 23°.

[0036] In the present implementation, the normal pressure angles of the intermediate gear wheel and the intermediate pinion are matched with the reduction ratio distribution of the first-stage transmission and the second-stage transmission, so that the radial forces of the input wheel acting on the intermediate gear wheel and the radial forces of the output wheel acting on the intermediate pinion are mostly canceled out, making the radial forces acting on the intermediate shaft and the tapered bearings at both ends smaller, and the stress of the power assembly is more balanced, which is conducive to improving the NVH performance of the power assembly.

[0037] In an implementation, the normal pressure angle of the intermediate large gear is equal to 17.5°, and the normal pressure angle of the intermediate small gear is equal to 21°.

[0038] In an implementation, the axial coincidence of the intermediate large gear and the input gear is greater than the axial coincidence of the intermediate small gear and the output gear.

[0039] In the implementation, the rotational speed of the input gear and the intermediate large gear in the first-stage transmission is high, and the engagement frequency of the input gear and the intermediate large gear is high. Increasing the axial coincidence of the input gear and the intermediate large gear in the first-stage transmission can increase the engagement line length between the input gear and the intermediate large gear, so that the engagement between the input gear and the intermediate large gear is more stable, and the noise excitation of the input gear and the intermediate large gear is reduced. The rotational speed of the intermediate small gear and the output gear in the second-stage transmission is low, and the engagement frequency of the intermediate small gear and the output gear is low. Reducing the axial coincidence of the output gear and the intermediate small gear in the second-stage transmission can also reduce the noise excitation of the output gear and the intermediate small gear.

[0040] In an implementation, the axial coincidence of the intermediate large gear and the input gear is greater than or equal to 3.9 and less than or equal to 4.1, and the axial coincidence of the intermediate small gear and the output gear is greater than or equal to 1.95 and less than or equal to 2.15.

[0041] In the implementation, the axial coincidence of the intermediate large gear and the input gear is large, which effectively increases the engagement line length between the input gear and the intermediate large gear, so that the engagement between the input gear and the intermediate large gear is more stable. The axial coincidence of the output gear and the intermediate small gear can also control the noise excitation of the second-stage transmission.

[0042] The axial coincidence of the intermediate large gear and the input gear is close to an integer. In the process of engagement transmission between the intermediate large gear and the input gear, the change range of the engagement line length of the two gears with the gear rotation angle is small, the stiffness change of the total engagement between the intermediate large gear and the input gear is small, the stability of the first-stage transmission is higher, and the NVH performance of the power assembly can be further improved.

[0043] The axial coincidence of the intermediate small gear and the output gear is also close to an integer. In the process of engagement transmission between the intermediate small gear and the output gear, the change range of the engagement line length of the two gears with the gear rotation angle is small, the stiffness change of the total engagement between the intermediate small gear and the output gear is small, the stability of the second-stage transmission is also higher, and the NVH performance of the power assembly can be further improved.

[0044] In an implementation, the axial coincidence of the intermediate large gear and the input gear is equal to 4.0362, and the axial coincidence of the intermediate small gear and the output gear is equal to 2.1246.

[0045] In the power assembly provided in the application, the axial coincidence degree of the first-stage transmission is more relevant to the parameters such as the reduction ratio, the helix angle, the effective meshing tooth width, the normal modulus and the normal pressure angle of the input shaft and the intermediate large gear. The axial coincidence degree of the second-stage transmission is more relevant to the parameters such as the reduction ratio, the helix angle, the effective meshing tooth width, the normal modulus and the normal pressure angle of the output shaft and the intermediate small gear. The axial coincidence degree of the first-stage transmission and the axial coincidence degree of the second-stage transmission obtained by the matching adjustment of the parameters of the intermediate large gear and the intermediate small gear of the power assembly respectively are close to integers, so that the overall transmission stability of the power assembly is higher, the meshing stiffness changes less, and the characteristics such as reducing the vibration excitation of the speed reducer and balancing the bearing stress of the speed reducer are taken into account, so that the overall NVH performance of the power assembly provided in the application is improved.

[0046] In an implementation, the speed reducer includes an input shaft and an output shaft, the input shaft is used for fixing an input gear and a motor shaft for transmission connection of a driving motor, and the output shaft is used for fixing an output gear and for driving a wheel. The input shaft and the output shaft are arranged on two sides of the intermediate large gear along the arrangement direction of the input gear and the intermediate large gear.

[0047] In the implementation, the speed reducer supports the input gear and the output gear through the input shaft and the output shaft respectively, cooperates with the intermediate large gear and the intermediate small gear fixed on the intermediate shaft to form the effect of two-stage transmission. The first-stage transmission is used for receiving the driving force of the driving motor through the input gear, and the second-stage transmission is used for outputting the driving force of the power assembly through the output gear.

[0048] In an implementation, the housing of the power assembly includes a speed reducer cavity for accommodating a gear set, the cavity wall of the speed reducer cavity includes two groups of bearing grooves, the two groups of bearing grooves are opposite along the axial direction of the motor shaft of the driving motor, each group of bearing grooves includes a plurality of bearing grooves, the plurality of bearing grooves are used for fixing the outer rings of a plurality of bearings respectively, and the inner rings of the plurality of bearings are used for being fixed to the input shaft, the output shaft and the intermediate shaft of the speed reducer respectively.

[0049] In the implementation, the input shaft, the output shaft and the intermediate shaft of the speed reducer are rotatably connected to the housing of the power assembly through bearings respectively. The housing of the power assembly also accommodates the input gear, the intermediate large gear, the intermediate small gear and the output gear of the speed reducer through the speed reducer cavity, thereby forming the accommodation and support of the speed reducer.

[0050] In a second aspect, the application provides an electric vehicle, which includes a vehicle frame, a power battery and the power assembly provided in any of the implementations. The vehicle frame is used for fixing the power battery and the power assembly, and the power assembly is used for driving the driving motor.

[0051] The electric vehicle provided in the second aspect of the present application has better NVH performance and improved user experience due to the power assembly provided in the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be described below.

[0053] Figure 1 The schematic diagram of the appearance structure of the electric vehicle provided in an embodiment of the present application is shown in FIG. 1.

[0054] Figure 2 The schematic diagram of the transmission structure of the power assembly provided in an embodiment of the present application is shown in FIG. 2.

[0055] Figure 3 The schematic diagram of the partial structure of the power assembly provided in an embodiment of the present application is shown in FIG. 3.

[0056] Figure 4 The schematic diagram of the partial structure of the power assembly provided in an embodiment of the present application is shown in FIG. 4.

[0057] Figure 5 The schematic diagram of the partial structure of the power assembly provided in an embodiment of the present application is shown in FIG. 5.

[0058] Figure 6 The schematic diagram of the force analysis of the power assembly provided in an embodiment of the present application is shown in FIG. 6.

[0059] Figure 7 The schematic diagram of the helical direction of the helical gear provided in an embodiment of the present application is shown in FIG. 7.

[0060] Figure 8 The schematic diagram of the helical direction of the helical gear provided in an embodiment of the present application is shown in FIG. 8.

[0061] Figure 9 The schematic diagram of the helical angle provided in an embodiment of the present application is shown in FIG. 9.

[0062] Figure 10 The schematic diagram of the partial structure of the power assembly provided in an embodiment of the present application is shown in FIG. 10.

[0063] BRIEF DESCRIPTION OF DRAWINGS: 1000 - electric vehicle; 1001 - vehicle frame; 1002 - vehicle wheel; 1003 - power battery; 100 - power assembly; 10 - housing; 11 - reducer cavity; 12 - bearing groove; 121 - first bearing groove; 122 - second bearing groove; 123 - third bearing groove; 20 - driving motor; 21 - motor shaft; 22 - motor rotor; 30 - reducer; 31 - gear set; 311 - input wheel; 312 - intermediate large gear; 313 - intermediate small gear; 314 - output wheel; 32 - transmission shaft; 321 - input shaft; 322 - intermediate shaft; 323 - output shaft; 40 - bearing; 40a - second bearing; 40b - second bearing; 40c - third bearing; 41 - outer ring; 42 - inner ring; 50 - helical gear; 51 - meshing tooth; 60 - differential. DETAILED DESCRIPTION

[0064] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments.

[0065] NVH: is the English abbreviation of Noise, Vibration, Harshness, that is, noise, vibration and sound roughness.

[0066] The present application provides a power assembly, the power assembly comprising a reducer and a driving motor, the gear set of the reducer comprising an input wheel, an intermediate large gear, an intermediate small gear and an output wheel, the input wheel being used for receiving the driving rotation of the driving motor, the intermediate large gear being used for engaging with the input wheel and for driving the intermediate small gear to rotate synchronously, the output wheel being used for engaging with the intermediate small gear and for driving the vehicle wheel. The reduction ratio of the input wheel engaging with the intermediate large gear is u1, the reduction ratio of the intermediate small gear engaging with the output wheel is u2, and 1.2≤u2:u1≤1.3.

[0067] The power assembly provided by the present application is connected in transmission between the driving motor and the vehicle wheel through the gear set. The power assembly reasonably distributes the reduction ratio between the first-stage transmission and the second-stage transmission, under the premise of satisfying the speed reduction and torque increase of the reducer, taking into account the bearing capacity of the bearing and the torque size borne by the transmission shaft, so that the working conditions of the gear set of the reducer are relatively balanced to improve the NVH performance.

[0068] The present application provides an electric vehicle, the electric vehicle comprising a vehicle frame, a power battery and the above-mentioned power assembly. The vehicle frame is used for fixing the power battery and the power assembly, and the power assembly is used for driving the driving motor. The electric vehicle provided by the present application has better NVH performance because of the adoption of the above-mentioned power assembly, and the user experience is improved.

[0069] Please see Figure 1 , Figure 1A schematic view of an appearance structure of an electric vehicle 1000 provided in an embodiment of the present application.

[0070] In an embodiment, the electric vehicle 1000 provided in the present application comprises a vehicle frame 1001 and a power assembly 100. The vehicle frame 1001 is configured to fix the power assembly 100. The power assembly 100 is configured to be in driving connection with one or more wheels 1002 of the electric vehicle 1000. The power assembly 100 is configured to drive the one or more wheels 1002 of the electric vehicle 1000 to rotate, thereby driving the electric vehicle 1000 to move.

[0071] The electric vehicle 1000 provided in the present application further comprises a power battery 1003. The power battery 1003 is fixed to the vehicle frame 1001 and is configured to be in electrical connection with the power assembly 100 to provide electric energy for the power assembly 100. The power assembly 100 is configured to receive the electric energy provided by the power battery 1003 to drive the one or more wheels 1002 to rotate.

[0072] In an embodiment, the electric vehicle 1000 provided in the present application comprises one power assembly 100, and the power assembly 100 is configured to drive a plurality of wheels 1002 to rotate. In another embodiment, the electric vehicle 1000 provided in the present application comprises a plurality of power assemblies 100, and each power assembly 100 is configured to drive part of the plurality of wheels 1002 to rotate.

[0073] Please see Figure 2 and Figure 3 , Figure 2 A schematic view of a transmission structure of the power assembly 100 provided in an embodiment of the present application; Figure 3 A schematic view of a partial structure of the power assembly 100 provided in an embodiment of the present application.

[0074] The power assembly 100 provided in the present application comprises a housing 10 and a driving motor 20. The housing 10 is configured to accommodate the driving motor 20, and the driving motor 20 is configured to be in electrical connection with the power battery 1003. The driving motor 20 is configured to receive the electric energy provided by the power battery 1003 and provide driving force to the one or more wheels 1002 through a motor shaft 21. That is, the power assembly 100 provided in the present application outputs driving force through the motor shaft 21 of the driving motor 20.

[0075] In an embodiment, the driving motor 20 comprises the motor shaft 21, a motor stator (not shown in the figure) and a motor rotor (not shown in the figure). The motor rotor is configured to be coaxially fixed to the motor shaft 21, and the motor stator is configured to be sleeved on the outer circumferential surface of the motor rotor along the radial direction of the motor shaft 21. The motor stator is configured to be in electrical connection with the power battery 1003. After receiving the electric energy provided by the power battery 1003, the motor stator drives the motor rotor to rotate, thereby driving the motor shaft 21 to rotate to output driving force.

[0076] In one embodiment, the axis of the motor shaft 21 of the drive motor 20 is parallel to the axis of at least one wheel 1002 corresponding to the powertrain 100, so that the powertrain 100 drives the wheel 1002 to rotate.

[0077] The powertrain 100 provided in this application includes a reducer 30, which is used to drive the motor shaft 21 of the drive motor 20 and one or more wheels 1002. The reducer 30 is used to adjust the speed and torque of the driving force output by the motor shaft 21 of the drive motor 20 and transmit the adjusted driving force to one or more wheels 1002.

[0078] In one embodiment, the reducer 30 includes a gear set 31 and a plurality of drive shafts 32, the plurality of drive shafts 32 being used to support and fix a plurality of gears in the gear set 31. The gear set 31 is used to drive the motor shaft 21 of the drive motor 20 and the wheel 1002, and the gear set 31 adjusts the speed and torque of the driving force output by the motor shaft 21 of the drive motor 20 by meshing different gears.

[0079] In one embodiment, the housing 10 includes a reducer cavity 11 for accommodating a gear set 31. Specifically, the cavity wall of the reducer cavity 11 includes two sets of bearing grooves, which are arranged opposite each other along the axial direction of the motor shaft 21 of the drive motor 20. Each set of bearing grooves includes multiple bearing grooves 12, which are used to fix the outer rings 41 of multiple bearings 40, and the inner rings 42 of multiple bearings 40 are used to fix and support multiple drive shafts 32. That is, the inner rings 42 of the bearings 40 in the two sets of bearing grooves 12 are used to support the two ends of the drive shafts 32. Thus, the gear set 31 of the reducer 30 is rotatably connected to the housing 10 through the drive shafts 32 and bearings 40.

[0080] Please refer to the above. Figure 4 and Figure 5 ,in Figure 4 This is a partial structural schematic diagram of the powertrain 100 provided in one embodiment of this application; Figure 5 This is a partial structural schematic diagram of the powertrain 100 provided in one embodiment of this application.

[0081] The gear set 31 of the reducer 30 includes an input gear 311, an intermediate large gear 312, an intermediate small gear 313, and an output gear 314. In one embodiment, the drive shaft 32 includes an input shaft 321, an intermediate shaft 322, and an output shaft 323. The input shaft 321, intermediate shaft 322, and output shaft 323 are arranged radially at intervals along the motor shaft 21 of the drive motor 20, and respectively extend axially along the motor shaft 21 of the drive motor 20, that is, the axes of the input shaft 321, intermediate shaft 322, and output shaft 323 are parallel. The input gear 311 is fitted and fixed to the input shaft 321, the intermediate large gear 312 and intermediate small gear 313 are fitted and fixed to the intermediate shaft 322, and the output gear 314 is fitted and fixed to the output shaft 323. That is, in this application, the input wheel 311 is supported and fixed by the input shaft 321, the intermediate large gear 312 and the intermediate small gear 313 are supported and fixed by the intermediate shaft 322, and the output wheel 314 is supported and fixed by the output shaft 323.

[0082] In one embodiment, each set of bearing grooves 12 includes a first bearing groove 121, a second bearing groove 122, and a third bearing groove 123 spaced apart. The bearing 40 includes a first bearing 40a, a second bearing 40b, and a third bearing 40c. The outer ring 41 of the first bearing 40a is fixed to the first bearing groove 121, and the inner ring 42 of the first bearing 40a is used to fix the input shaft 321. The outer ring 41 of the second bearing 40b is fixed to the second bearing groove 122, and the inner ring 42 of the second bearing 40b is used to fix the intermediate shaft 322. The outer ring 41 of the third bearing 40c is fixed to the third bearing groove 123, and the inner ring 42 of the third bearing 40c is used to fix the output shaft 323. That is, the input shaft 321, the intermediate shaft 322, and the output shaft 323 are rotatably connected to the housing 10 of the powertrain 100 via the first bearing 40a, the second bearing 40b, and the third bearing 40c, respectively. Thus, the input wheel 311, the intermediate large gear 312 and the intermediate small gear 313, and the output wheel 314 are rotatably connected to the housing 10 via the input shaft 321, the intermediate shaft 322, and the output shaft 323, respectively.

[0083] The input wheel 311 receives the drive rotation from the drive motor 20. The intermediate large gear 312 meshes with the output wheel 314 and drives the intermediate small gear 313 to rotate synchronously. The output wheel 314 meshes with the intermediate small gear 313 and drives the wheel 1002. The reduction ratio of the input wheel 311 meshing with the intermediate large gear 312 is u1, and the reduction ratio of the intermediate small gear 313 meshing with the output wheel 314 is u2, where 1.2 ≤ u2 : u1 ≤ 1.3.

[0084] The powertrain 100 provided in this application achieves the function of reducing speed and increasing torque of the reducer 30 through the interaction of the input wheel 311, the intermediate large gear 312, the intermediate small gear 313, and the output wheel 314. The diameter of the input wheel 311 is smaller than the diameter of the intermediate large gear 312. The input wheel 311 meshes with the intermediate large gear 312 to form the first stage of transmission in the reducer 30, achieving speed reduction and torque increase in the first stage. The diameter of the intermediate small gear 313 is smaller than the diameter of the output wheel 314. The intermediate small gear 313 meshes with the output wheel 314 to form the second stage of transmission in the reducer 30, achieving speed reduction and torque increase in the second stage. Therefore, the reducer 30 of this application can achieve two-stage speed reduction, thereby significantly reducing the speed of the driving force output by the drive motor 20 and significantly increasing the torque of the driving force output by the drive motor 20.

[0085] This application also improves the NVH performance of the powertrain 100 provided by optimizing the reduction ratio u1 between the input gear 311 and the intermediate large gear 312, and the reduction ratio u2 between the intermediate small gear 313 and the output gear 314. Specifically, by limiting the relationship between u1 and u2 to satisfy 1.2≤u2:u1≤1.3, the reduction ratio u1 of the first stage transmission is less than the reduction ratio u2 of the second stage transmission, ensuring that the reducer 30 can achieve the effect of speed reduction and torque increase. At the same time, limiting the ratio of the reduction ratio u2 of the second stage transmission to the reduction ratio u1 of the first stage transmission to be less than or equal to 1.3 can avoid the phenomenon that the bearing 40 of the transmission shaft 32 used to support the intermediate small gear 313 rotates too fast and exceeds the bearing 40's bearing capacity limit due to the excessive reduction ratio of the second stage transmission. Furthermore, limiting the ratio of the reduction ratio u2 of the second-stage transmission to the reduction ratio u1 of the first-stage transmission to be greater than or equal to 1.2 can prevent the transmission shaft 32 from experiencing excessive vibration and excessive noise due to excessive torque on the transmission shaft 32 used to support the intermediate pinion 313 caused by an excessively small reduction ratio of the second-stage transmission. In other words, the powertrain 100 provided in this application, by reasonably distributing the reduction ratio between the first-stage and second-stage transmissions, satisfies the requirement of speed reduction and torque increase in the reducer 30, while also taking into account the load-bearing capacity of the bearing 40 and the torque carried by the transmission shaft 32, resulting in a relatively balanced operating condition of the gear set 31 of the reducer 30 to improve NVH performance.

[0086] In one embodiment, the reducer 30 includes an intermediate shaft 322. The middle section of the intermediate shaft 322 is used to fix an intermediate large gear 312 and an intermediate small gear 313. The two ends of the intermediate shaft 322 are respectively used to fix the inner ring 42 of a tapered bearing 40. The outer rings 41 of the two tapered bearings 40 are respectively fixed to the housing 10 of the reducer 30.

[0087] Along the axial direction of the intermediate shaft 322, the cavity wall of the reducer cavity 11 includes two opposing second bearing grooves 122, each second bearing groove 122 for fixing a second bearing 40b, wherein the second bearing 40b is a tapered bearing 40. The transmission shaft 32 includes an intermediate shaft 322, an intermediate large gear 312 and an intermediate small gear 313 for coaxial fixing with the intermediate shaft 322. Along the axial direction of the intermediate shaft 322, one tapered bearing 40, the intermediate large gear 312, the intermediate small gear 313 and the other tapered bearing 40 are arranged in sequence. The inner ring 42 and the outer ring 41 of one tapered bearing 40 are fixed to one end of the intermediate shaft 322 and a second bearing groove 122, respectively, and the inner ring 42 and the outer ring 41 of the other tapered bearing 40 are fixed to the other end of the intermediate shaft 322 and a second bearing groove 122, respectively. Thus, the intermediate large gear 312 and the intermediate small gear 313 are supported and rotatably connected to the housing 10 by the intermediate shaft 322 and the two tapered bearings 40.

[0088] During the operation of the powertrain 100 provided in this application, the motor shaft 21 of the drive motor 20 rotates to drive the input wheel 311 to rotate the intermediate large gear 312 meshing with the input wheel 311. The rotation of the intermediate large gear 312 drives the intermediate shaft 322 to rotate synchronously and drives the intermediate small gear 313 to rotate. The rotation of the intermediate small gear 313 drives the output wheel 314 meshing with the intermediate small gear 313 to rotate. The rotation of the output wheel 314 drives the wheel 1002 to rotate to realize the driving function of the powertrain 100 provided in this application.

[0089] Please refer to the above. Figure 6 , Figure 6 This is a schematic diagram of the force analysis of the powertrain 100 provided in one embodiment of this application. Since the input wheel 311 and output wheel 314 mesh with the intermediate large gear 312 and intermediate small gear 313 respectively, during the meshing transmission of the input wheel 311 and the intermediate large gear 312, the input wheel 311 generates a tangential force F1 on the meshing line. This tangential force F1 can be decomposed into an axial component along the axis of the intermediate large gear 312 and a radial component perpendicular to the axis of the intermediate large gear 312. During the meshing transmission of the output wheel 314 and the intermediate small gear 313, the output wheel 314 generates another tangential force F2 on the meshing line. This tangential force F2 can be decomposed into an axial component along the axis of the intermediate small gear 313 and a radial component perpendicular to the axis of the intermediate small gear 313. The axial components along the axis of the intermediate large gear 312 and the axial components along the axis of the intermediate small gear 313, as well as their resultant force, will cause the intermediate shaft 322 to move axially.

[0090] This application provides a tapered bearing 40 at each end of the intermediate shaft 322. The two tapered bearings 40 can respectively generate axial thrust on the intermediate shaft 322 to offset part of the axial component force generated by the input wheel 311 on the intermediate large gear 312 and the axial component force generated by the output wheel 314 on the intermediate small gear 313. This reduces the axial movement of the intermediate shaft 322, reduces the noise generated by the axial movement of the reducer 30 due to the intermediate shaft 322, and improves the NVH performance of the powertrain 100 provided by this application.

[0091] In one embodiment, both the intermediate large gear 312 and the intermediate small gear 313 are helical gears, and the helical directions of the intermediate large gear 312 and the intermediate small gear 313 are the same.

[0092] Helical gears have a large meshing surface and strong load-bearing capacity during meshing. Furthermore, because the tooth tips and roots of helical gears are inclined, their meshing process is gradual, reducing impact and vibration and resulting in smoother transmission. This application designs the intermediate large gear 312 and intermediate small gear 313 as helical gears, which not only meets the torque transmission requirements of the reducer 30 but also improves the smoothness of the transmission and enhances the NVH performance of the powertrain 100.

[0093] To better understand the helical direction of a helical gear, please refer to [link / reference]. Figure 7 and Figure 8 .in Figure 7 This is a schematic diagram showing the helical direction of the helical gear 50 provided in one embodiment of this application; Figure 8 This is a schematic diagram of the helical direction of the helical gear 50 provided in one embodiment of this application.

[0094] exist Figure 7 In the illustration, the helical gear 50 has a right-hand helix direction. That is, when the helical gear 50 is placed vertically along its axis (i.e., the direction indicated by the arrow in the diagram), the helix S extending to the upper right corner indicates a right-hand helix. Figure 8 In the illustration, the spiral gear 50 has a left-hand spiral direction. That is, when the spiral gear 50 is placed vertically along the axial direction (that is, the direction indicated by the arrow in the figure), the spiral line S extends to the upper left corner, which indicates a left-hand spiral direction.

[0095] Because the intermediate large gear 312 and the intermediate small gear 313 are coaxially driven, their helical directions are the same. In one embodiment, the helical direction of the intermediate large gear 312 is right-handed, and the helical direction of the intermediate small gear 313 is also right-handed. Based on the meshing characteristics, the helical direction of the intermediate large gear 312 must be opposite to the helical direction of the input gear 311, and the helical direction of the intermediate small gear 313 must be opposite to the helical direction of the output gear 314. That is, the helical directions of both the input gear 311 and the output gear 314 are left-handed.

[0096] In one embodiment, the helix angle of the intermediate large gear 312 is greater than the helix angle of the intermediate small gear 313. For ease of explanation, this application defines the helix angle of the intermediate large gear 312 as γ1 and the helix angle of the intermediate small gear 313 as γ2, where γ1 > γ2. For a clearer understanding of the helix angle, please refer to [link to relevant documentation]. Figure 9 ,in Figure 9 This is a schematic diagram of the helix angle provided in one embodiment of this application. Figure 9 In the illustration, the helix angle is γ. The helix angle is the acute angle between the tangent of the cylindrical helix S and the generatrix of the cylindrical surface passing through the point of tangency, used to describe the inclination of the tooth surface line relative to the axis. In one embodiment, the helix angle γ is tested as follows: the outer circumferential surface of the helical gear 50 includes multiple meshing teeth 51. The outer circumferential surface of the helical gear 50 is unfolded to obtain a plane N. The circumferential direction of the helical gear 50 is the first direction B after unfolding. The normal E of each meshing tooth 51 is perpendicular to the extension direction of the meshing tooth 51. The angle between the intersection line L1 of the normal E of each meshing tooth 51 and the plane N and the first direction B is the helix angle γ. Another method for testing the helix angle γ is as follows: the angle between the helix S and the axial direction O on the plane N is the helix angle γ. Under other constant conditions, the larger the helix angle γ, the larger the tooth pitch and number of teeth of the helical gear 50, and the larger the axial component force.

[0097] During the operation of the powertrain 100 provided in this application, the input wheel 311 and the output wheel 314 exert opposite axial forces on the gear set 31 formed by the intermediate large gear 312 and the intermediate small gear 313, thereby exerting opposite axial forces on the intermediate shaft 322 used to fix the intermediate large gear 312 and the intermediate small gear 313. One embodiment is described below. Figure 3 During the transmission process between the input wheel 311 and the intermediate large gear 312, the axial component force generated by the input wheel 311 on the intermediate shaft 322 is A1. During the transmission process between the intermediate small gear 313 and the output wheel 314, the axial component force generated by the output wheel 314 on the intermediate shaft 322 is A2. The directions of A1 and A2 are opposite.

[0098] Because the reduction ratio u1 of the first stage of the reducer 30 is less than the reduction ratio u2 of the second stage, the torque of the intermediate large gear 312 meshing with the input wheel 311 is small, while the torque of the intermediate small gear 313 meshing with the output wheel 314 is large. When the ratio of the reduction ratio u1 of the first stage to the reduction ratio u2 of the second stage is constant, this application, by setting the helix angle γ1 of the intermediate large gear 312 to be greater than the helix angle γ2 of the intermediate small gear 313, facilitates a larger axial component of the force generated when the intermediate large gear 312 meshes with the input wheel 311, while the axial component of the force generated when the intermediate small gear 313 meshes with the output wheel 314 is smaller. This results in A1 > A2. Since the intermediate large gear 312, with its smaller torque, experiences a larger axial component, and the intermediate small gear 313, with its larger torque, experiences a smaller axial component, the final axial force experienced by the intermediate large gear 312 and the intermediate small gear 313 is relatively small in magnitude and opposite in direction.

[0099] When the intermediate pinion 313 and intermediate gear 312 transmit the axial force to the intermediate shaft 322, the axial forces with small differences in magnitude and opposite directions mostly cancel each other out. This allows the intermediate shaft 322 and the tapered bearings 40 at both ends to be subjected to a smaller axial force, making the powertrain 100 provided by this application more balanced in terms of force, thereby improving the NVH performance of the powertrain 100 provided by this application.

[0100] Furthermore, by designing a larger helix angle γ1 for the intermediate large gear 312 meshing with the input gear 311, the high-speed transmission requirements of the input gear 311 can be met. After the input gear 311 transmits power to the intermediate large gear 312, the speeds of the intermediate shaft 322 and the intermediate small gear 313 decrease. The smaller helix angle γ2 for the intermediate small gear 313 meshing with the output gear 314 is also sufficient to meet the lower-speed transmission requirements of the intermediate small gear 313.

[0101] In one embodiment, the helix angle of the intermediate large gear 312 is greater than or equal to 26° and less than or equal to 30°, and the helix angle of the intermediate small gear 313 is greater than or equal to 20° and less than or equal to 24°. That is, 26°≤γ1≤30°; 20°≤γ2≤24°.

[0102] In this embodiment, since the reduction ratio of the second-stage transmission to the first-stage transmission is between 1.2 and 1.3, this application sets the helix angle of the intermediate large gear 312 to between 26° and 30°, and the helix angle of the intermediate small gear 313 to between 20° and 24°, so that the helix angles of the intermediate large gear 312 and the intermediate small gear 313 match the reduction ratio distribution of the first-stage and second-stage transmissions. This ensures that the axial force of the input wheel 311 on the intermediate large gear 312 and the axial force of the output wheel 314 on the intermediate small gear 313 are largely canceled out, resulting in a smaller axial force on the intermediate shaft 322 and the tapered bearings 40 at both ends. This makes the force distribution of the powertrain 100 provided by this application more balanced, which is beneficial to improving the NVH performance of the powertrain 100 provided by this application.

[0103] In one embodiment, the helix angle of the intermediate large gear 312 is 28°, and the helix angle of the intermediate small gear 313 is 21.8°. That is, γ1 = 28°; γ2 = 21.8°.

[0104] In one embodiment, the helix angle of the input wheel 311 is the same as that of the intermediate large gear 312. This allows the input wheel 311 to mesh better with the intermediate large gear 312, resulting in a higher degree of overlap when the input wheel 311 and the intermediate large gear 312 mesh, which is beneficial for power transmission.

[0105] In one embodiment, the helix angle of the output wheel 314 is the same as that of the intermediate pinion 313. This allows the output wheel 314 to mesh better with the intermediate pinion 313, resulting in a higher degree of overlap when the output wheel 314 and the intermediate pinion 313 mesh, which is beneficial for power transmission.

[0106] In one embodiment, the helical directions of the intermediate large gear 312 and the intermediate small gear 313 are both right-handed.

[0107] Please refer to the above. Figure 10 , Figure 10 This is a partial structural schematic diagram of a powertrain 100 provided in one embodiment of this application.

[0108] In one implementation, along the axial direction of the powertrain 100, the intermediate pinion 313, the intermediate gear 312, and the motor rotor 22 of the drive motor 20 are arranged sequentially. That is, along the axial direction of the transmission shaft 32, the output wheel 314, the input wheel 311, and the motor rotor 22 of the drive motor 20 are arranged sequentially. Alternatively, it can be understood that along the axial direction of the transmission shaft 32, the motor rotor 22 of the drive motor 20 is closer to the intermediate gear 312 than the intermediate pinion 313. The drive motor 20 serves as the power source, the input wheel 311 serves as the power input end for transmission connection with the drive motor 20, and the output wheel 314 serves as the power output end for connection with the wheel 1002. In this embodiment, the intermediate gear 312 meshing with the output wheel 314 is positioned closer to the motor rotor 22 of the drive motor 20; that is, the first stage of transmission in the reducer 30 is positioned closer to the drive motor 20 than the second stage of transmission, resulting in a more rational arrangement and facilitating the miniaturization of the powertrain 100 provided in this application.

[0109] The effective meshing width between the intermediate large gear 312 and the input gear 311 is smaller than the effective meshing width between the intermediate small gear 313 and the output gear 314. For ease of explanation, this application defines the effective meshing width between the intermediate large gear 312 and the input gear 311 as bw1, and the effective meshing width between the intermediate small gear 313 and the output gear 314 as bw2, where bw1 < bw2. That is, the effective meshing width of the first-stage transmission is smaller than the effective meshing width of the second-stage transmission. The effective meshing width refers to the lateral width of the actual contact between the tooth surfaces when the gear teeth mesh. In this embodiment, the lateral width of the actual contact between the tooth surfaces of the intermediate large gear 312 and the input gear 311 when they mesh is smaller than the lateral width of the actual contact between the tooth surfaces of the intermediate small gear 313 and the output gear 314 when they mesh. It should be noted that the effective meshing width determines the contact area of ​​the meshing. Under the same conditions, the larger the effective meshing width, the larger the contact area, thus enabling it to withstand greater loads, improve load-bearing capacity, and extend service life. However, it also increases the processing difficulty.

[0110] In this embodiment, since the reduction ratio of the second-stage transmission is greater than that of the first-stage transmission, the torque required to be transmitted by the second-stage transmission is greater. By setting the effective meshing width of the second-stage transmission to be larger, it has a suitable load-bearing capacity, thereby better adapting to the torque transmitted between the intermediate pinion 313 and the output wheel 314.

[0111] In one embodiment, the effective meshing width between the intermediate large gear 312 and the input gear 311 is greater than or equal to 40 mm and less than or equal to 43 mm, and the effective meshing width between the intermediate small gear 313 and the output gear 314 is greater than or equal to 46 mm and less than or equal to 50 mm. That is, 40 mm ≤ bw1 ≤ 43 mm; 46 mm ≤ bw2 ≤ 50 mm.

[0112] In this embodiment, since the reduction ratio of the second-stage transmission is between 1.2 and 1.3, this application sets the effective meshing width between the intermediate large gear 312 and the input gear 311 to between 40mm and 43mm, and the effective meshing width between the intermediate small gear 313 and the output gear 314 to between 46mm and 50mm. This avoids both excessively large effective meshing widths that reduce the machining performance of the meshing teeth 51 and excessively small effective meshing widths that reduce load-bearing capacity and service life. Furthermore, this design ensures that the distribution of the effective meshing widths between the first and second-stage transmissions matches the distribution of their reduction ratios, resulting in a higher load-bearing capacity for the second-stage transmission to meet its high torque transmission requirements and guarantee the reliable operation of the powertrain 100 provided in this application.

[0113] In one embodiment, the effective meshing width between the intermediate large gear 312 and the input gear 311 is 41 mm, and the effective meshing width between the intermediate small gear 313 and the output gear 314 is 47 mm. That is, bw1 = 41 mm; bw2 = 47 mm.

[0114] In one embodiment, the tooth width of the intermediate large gear 312 is 41 mm, and the tooth width of the intermediate small gear 313 is 50 mm. The tooth width refers to the axial length of the gear teeth. The size of the tooth width affects the load-bearing capacity and the distribution of tooth loads. Under otherwise constant conditions, a larger tooth width results in a greater load-bearing capacity. In this embodiment, the sum of the tooth widths of the intermediate large gear 312 and the intermediate small gear 313 is limited by the axial length of the intermediate shaft 322. By setting the tooth width of the intermediate large gear 312 to 41 mm and the tooth width of the intermediate small gear 313 to 50 mm, the tooth widths of the intermediate large gear 312 and the intermediate small gear 313 are reasonably distributed, thereby enabling the intermediate small gear 313 to have a higher load-bearing capacity to meet the high torque transmission requirements of the intermediate small gear 313. Furthermore, the machinability of the intermediate large gear 312 and the intermediate small gear 313 is also considered.

[0115] In one embodiment, the input wheel 311 has a tooth width of 44 mm, and the output wheel 314 has a tooth width of 47 mm.

[0116] The tooth widths of the input gear 311 and the output gear 314 are matched with the tooth widths of the intermediate large gear 312 and the intermediate small gear 313, respectively. The input gear 311, as the driving gear in the first stage of transmission, has a wider tooth width than the intermediate large gear 312, which is the driven gear in the first stage. Therefore, when axial movement occurs in the intermediate shaft 322, it ensures that the intermediate large gear 312 meshes with the input gear 311 along the full axial dimension of the intermediate shaft 322, preventing the axial misalignment between the intermediate large gear 312 and the input gear 311 from reducing the effective meshing width, thereby improving the torque transmission capacity of the first stage transmission. Correspondingly, the intermediate small gear 313, as the driving gear in the second stage of transmission, has a wider tooth width than the output gear 314, which is the driven gear in the second stage. Therefore, when the intermediate shaft 322 moves, the output wheel 314 can be fully engaged with the intermediate pinion 313 along the axial dimension of the intermediate shaft 322, avoiding the reduction of the effective meshing width between the intermediate pinion 313 and the output wheel 314 due to axial misalignment of the intermediate pinion 313 and the output wheel 314, thereby improving the torque transmission capability of the second stage transmission.

[0117] In one embodiment, the normal module of the intermediate large gear 312 is smaller than the normal module of the intermediate small gear 313. For ease of explanation, this application defines the normal module of the intermediate large gear 312 as Mn1 and the normal module of the intermediate small gear 313 as Mn2, where Mn1 < Mn2. That is, the normal module of the first stage of transmission is smaller than the normal module of the second stage of transmission. It should be noted that the normal module refers to the module perpendicular to the gear helix direction. The normal module affects the strength, size, and transmission performance of the gear. Under other constant conditions, the larger the normal module, the larger the tooth profile of the gear, the higher the load-bearing capacity, the higher the processing difficulty, and the greater the noise generated during meshing.

[0118] In this embodiment, because the rotational speed of the first-stage transmission is higher than that of the second-stage transmission, the normal module of the first transmission is controlled to be smaller, which helps to reduce the noise generated by the meshing transmission between the input wheel 311 and the intermediate large gear 312. Because the torque of the second-stage transmission is larger than that of the first-stage transmission, the module of the second-stage transmission is controlled to be larger, which helps to improve the torque carrying capacity of the second-stage transmission.

[0119] In one embodiment, the normal module of the intermediate large gear 312 is greater than or equal to 1.48 and less than or equal to 1.55, and the normal module of the intermediate small gear 313 is greater than or equal to 2.55 and less than or equal to 2.75. That is, 1.48≤Mn1≤1.55; 2.55≤Mn2≤2.75.

[0120] In this embodiment, the normal module of the intermediate large gear 312 is set to be greater than or equal to 1.48, so that the meshing teeth 51 of the intermediate large gear 312 and the input wheel 311 each have a certain tooth thickness. This avoids tooth tip hardening after heat treatment of the intermediate large gear 312 or the input wheel 311, which would shorten the service life of the tooth tips and potentially cause poor NVH performance due to tooth tip damage. Setting the normal module of the intermediate large gear 312 to be less than or equal to 1.55 can reduce the noise generated when the input wheel 311 meshes with the intermediate large gear 312. That is, setting the normal module of the intermediate large gear 312 to be between 1.48 and 1.55 ensures that the meshing teeth 51 of the intermediate large gear 312 have a certain strength while reducing the noise generated when the intermediate large gear 312 meshes with the input wheel 311.

[0121] Setting the normal module of the intermediate pinion 313 to be greater than or equal to 2.55 ensures reliable meshing and torque transmission between the intermediate pinion 313 and the output gear 314. Setting the normal module of the intermediate pinion 313 to be less than or equal to 2.75 improves the machinability of both the intermediate pinion 313 and the output gear 314. In other words, setting the normal module of the intermediate pinion 313 to be between 2.55 and 2.75 ensures that the larger torque requirement of the second-stage transmission is met while also improving the machinability of both the intermediate pinion 313 and the output gear 314.

[0122] In one embodiment, the normal module of the intermediate large gear 312 is equal to 1.518, and the normal module of the intermediate small gear 313 is equal to 2.615. That is, Mn1 = 1.518; Mn2 = 2.615.

[0123] It should be noted that the normal pressure angle τ refers to the angle between the gear tooth profile and the radial line in the normal plane. The test method for the pressure angle τ is as follows: Figure 9 As shown, the outer circumferential surface of the gear includes multiple meshing teeth 51. Unfolding the outer circumferential surface of the gear yields a plane N. The normal plane E of each meshing tooth 51 is perpendicular to its extension direction. The tooth profile of each meshing tooth 51 on the normal plane E is denoted as L2, and the radial line of the meshing tooth 51 is denoted as L3. The direction R of the radial line L3 is perpendicular to plane N. The angle between the tooth profile L2 and the radial line L3 is the normal pressure angle τ. Under constant conditions, a smaller normal pressure angle results in a larger axial overlap, lower load-bearing capacity, and lower machinability.

[0124] In one embodiment, the normal pressure angle of the intermediate large gear 312 is smaller than the normal pressure angle of the intermediate small gear 313. For ease of explanation, this application defines the normal pressure angle of the intermediate large gear 312 as τ1 and the normal pressure angle of the intermediate small gear 313 as τ2, where τ1 < τ2.

[0125] In this embodiment, the output wheel 314 of the reducer 30 bears a large load, resulting in a large radial force on the intermediate pinion 313 when it is connected to the output wheel 314. Setting the normal pressure angle of the intermediate pinion 313 to be large increases its load-bearing capacity, allowing it to withstand the large radial force from the output wheel 314 and preventing breakage of the meshing teeth 51. Conversely, the input wheel 311 bears a smaller load, so setting the normal pressure angle of the intermediate gear 312 to be smaller also meets its load requirements. Furthermore, a smaller pressure angle of the intermediate gear 312 results in a larger axial overlap between the intermediate gear 312 and the input wheel 311, which is beneficial for greater reliability and better NVH performance when the input wheel 311 rotates at high speeds.

[0126] This application sets the normal pressure angle of the intermediate pinion 313 to be greater than that of the intermediate large gear 312. This makes the resultant force of the radial force exerted by the input wheel 311 on the intermediate large gear 312 and the radial force exerted by the output wheel 314 on the intermediate pinion 313 smaller. As a result, the tapered bearings 40 fixed at both ends of the intermediate shaft 322 can bear a smaller radial component force, making the force on the powertrain 100 provided by this application more balanced and improving NVH performance.

[0127] In one implementation, the normal pressure angle of the intermediate large gear 312 is greater than or equal to 15° and less than or equal to 18°, and the normal pressure angle of the intermediate small gear 313 is greater than or equal to 20° and less than or equal to 23°. That is, 15°≤τ1≤18°; 20°≤τ2≤23°.

[0128] In this embodiment, since the reduction ratio of the second-stage transmission to the first-stage transmission is between 1.2 and 1.3, this application sets the pressure angle of the intermediate large gear 312 to between 15° and 18°, and the pressure angle of the intermediate small gear 313 to between 20° and 23°. This avoids both excessively small pressure angles that reduce machining performance and excessively large pressure angles that reduce end face overlap and load-bearing capacity. Furthermore, this design matches the normal pressure angles of the intermediate large gear 312 and intermediate small gear 313 with the reduction ratio distribution of the first and second-stage transmissions. This allows the radial force from the input wheel 311 on the intermediate large gear 312 and the radial force from the output wheel 314 on the intermediate small gear 313 to be largely canceled out, resulting in a smaller radial force on the intermediate shaft 322 and the tapered bearings 40 at both ends. Therefore, the powertrain 100 provided by this application experiences more balanced forces, which is beneficial for improving the NVH performance of the powertrain 100.

[0129] In one embodiment, the normal pressure angle of the intermediate large gear 312 is equal to 17.5°, and the normal pressure angle of the intermediate small gear 313 is equal to 21°. That is, τ1 = 17.5°; τ2 = 21°.

[0130] It should be noted that axial overlap is the ratio of the actual line of contact of a gear to the pitch of its base circle. It reflects the degree of overlap between meshing gears on the same axis, and its magnitude reflects the duration of contact between the meshing teeth during meshing. Under constant conditions, a higher axial overlap results in lower axial vibration and axial load during transmission, leading to higher transmission efficiency. It also contributes to improved transmission stability and load-bearing capacity. A higher axial overlap also improves the meshing accuracy of gears, reduces transmission errors, lowers noise and wear, and extends gear life.

[0131] In one embodiment, the axial overlap of the intermediate large gear 312 meshing with the input gear 311 is greater than the axial overlap of the intermediate small gear 313 meshing with the output gear 314. For ease of explanation, this application defines the axial overlap of the intermediate large gear 312 meshing with the input gear 311 as ε1, and the axial overlap of the intermediate small gear 313 meshing with the output gear 314 as ε2, where ε1 > ε2.

[0132] In this embodiment, the input wheel 311 and the intermediate large gear 312 rotate at higher speeds in the first-stage transmission, resulting in a higher meshing frequency between them. By setting a larger axial overlap between the input wheel 311 and the intermediate large gear 312 in the first-stage transmission, the meshing line between them can be lengthened, leading to smoother meshing and reduced noise excitation. Conversely, the intermediate small gear 313 and the output wheel 314 rotate at lower speeds in the second-stage transmission, resulting in a lower meshing frequency. Setting a smaller axial overlap between the output wheel 314 and the intermediate small gear 313 in the second-stage transmission also reduces noise excitation and simplifies the design.

[0133] In one embodiment, the axial overlap of the intermediate large gear 312 meshing with the input gear 311 is greater than or equal to 3.9 and less than or equal to 4.1, and the axial overlap of the intermediate small gear 313 meshing with the output gear 314 is greater than or equal to 1.95 and less than or equal to 2.15. That is, 3.9≤ε1≤4.1; 1.95≤ε2≤2.15.

[0134] In this embodiment, the axial overlap between the intermediate large gear 312 and the input gear 311 is relatively large, effectively increasing the meshing line length between the input gear 311 and the intermediate large gear 312, resulting in smoother meshing between them. The axial overlap between the output gear 314 and the intermediate small gear 313 also controls the noise excitation of the second-stage transmission.

[0135] Furthermore, the axial overlap of the intermediate large gear 312 and the input gear 311 is close to an integer. During the meshing transmission process between the intermediate large gear 312 and the input gear 311, the length of the meshing line between the two changes little with the gear rotation angle. The change in the overall meshing stiffness between the intermediate large gear 312 and the input gear 311 is small, resulting in higher smoothness of the first stage transmission and further improving the NVH performance of the powertrain 100.

[0136] The axial overlap of the intermediate pinion 313 and the output wheel 314 is also close to an integer. During the meshing transmission process between the intermediate pinion 313 and the output wheel 314, the length of the meshing line between the two changes little with the gear rotation angle. The change in the overall meshing stiffness between the intermediate pinion 313 and the output wheel 314 is small, and the smoothness of the second-stage transmission is also high, which can further improve the NVH performance of the powertrain 100.

[0137] In one embodiment, the input wheel 311 has 25 teeth, the intermediate large gear 312 has 82 teeth, the intermediate small gear 313 has 17 teeth, and the output wheel 314 has 71 teeth.

[0138] In one embodiment, the pitch circle diameter of the input wheel 311 is 42.98 mm, the pitch circle diameter of the intermediate large gear 312 is 144.16 mm, the pitch circle diameter of the intermediate small gear 313 is 50.695 mm, and the pitch circle diameter of the output wheel 314 is 207.554 mm.

[0139] In one embodiment, the input wheel 311 has a tooth width of 44 mm, the intermediate large gear 312 has a tooth width of 41 mm, the intermediate small gear 313 has a tooth width of 50 mm, and the output wheel 314 has a tooth width of 47 mm.

[0140] In one embodiment, the axial overlap of the intermediate large gear 312 meshing with the input gear 311 is 4.0362, and the axial overlap of the intermediate small gear 313 meshing with the output gear 314 is 2.1246. That is, ε1 = 4.0362, ε2 = 2.1246.

[0141] In the powertrain 100 provided in this application, the axial overlap of the first-stage transmission is highly correlated with parameters such as the reduction ratio, helix angle, effective meshing tooth width, normal module, and normal pressure angle of the input shaft 321 and the intermediate large gear 312. The axial overlap of the second-stage transmission is highly correlated with parameters such as the reduction ratio, helix angle, effective meshing tooth width, normal module, and normal pressure angle of the output shaft 323 and the intermediate small gear 313. By matching and adjusting the parameters of the intermediate large gear 312 and the intermediate small gear 313 respectively, the axial overlap of the first-stage transmission and the second-stage transmission of the powertrain 100 provided in this application are close to integers. This results in high overall transmission smoothness and small changes in meshing stiffness of the powertrain 100, while also reducing vibration excitation of the reducer 30 and balancing the stress on the bearing 40 of the reducer 30. As a result, the overall NVH performance of the powertrain 100 provided in this application is improved.

[0142] In one embodiment, the reducer 30 includes an input shaft 321 and an output shaft 323. The input shaft 321 is used to fix the input wheel 311 and the motor shaft 21 for driving the drive motor 20. The output shaft 323 is used to fix the output wheel 314 and drive the wheel 1002. The input shaft 321 and output shaft 323 are arranged on both sides of the intermediate large gear 312 along the arrangement direction of the input wheel 311 and the intermediate large gear 312. In this embodiment, the reducer 30 supports the input wheel 311 and the output wheel 314 respectively via the input shaft 321 and the output shaft 323, and, in conjunction with the intermediate large gear 312 and the intermediate small gear 313 fixed by the intermediate shaft 322, forms a two-stage transmission effect. It receives the driving force of the drive motor 20 through the input shaft 321 and outputs the driving force to the wheel 1002 through the output shaft 323. That is, the first stage of transmission receives the driving force of the drive motor 20 through the input wheel 311, and the second stage of transmission outputs the driving force of the powertrain 100 through the output wheel 314.

[0143] In one embodiment, the powertrain 100 provided in this application further includes a differential 60, which is used for transmission connection with the output wheel 314 and the wheel 1002. Along the axial direction of the motor shaft 21 of the drive motor 20, the differential 60 is located on the side of the output wheel 314 closer to the drive motor 20. In this embodiment, the differential 60 distributes the torque output from the output wheel 314 to the two wheels 1002 to meet the driving needs of the electric vehicle 1000 under different conditions. By placing the differential 60 and the drive motor 20 on the same side of the output wheel 314, the differential 60 does not occupy additional space outside the axial direction of the drive motor 20 of the powertrain 100, which is beneficial to the miniaturization of the powertrain 100 provided in this application, thereby optimizing the overall vehicle layout.

[0144] 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 description of the embodiments above is 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 in that, The powertrain includes a reducer and a drive motor. The gear set of the reducer includes an input gear, a large intermediate gear, a small intermediate gear, and an output gear. The input gear receives the drive rotation from the drive motor. The large intermediate gear meshes with the input gear and drives the small intermediate gear to rotate synchronously. The output gear meshes with the small intermediate gear and drives the wheels. The reduction ratio of the input wheel meshing with the intermediate large gear is u1, and the reduction ratio of the intermediate small gear meshing with the output wheel is u2, where 1.2≤u2:u1≤1.

3.

2. The powertrain according to claim 1, characterized in that, The reducer includes an intermediate shaft, the middle section of which is used to fix the intermediate large gear and the intermediate small gear, and the two ends of the intermediate shaft are respectively used to fix the inner ring of a tapered bearing, and the outer rings of the two tapered bearings are respectively fixed to the housing of the reducer.

3. The powertrain according to claim 1, characterized in that, Both the intermediate large gear and the intermediate small gear are helical gears, and the helical directions of the intermediate large gear and the intermediate small gear are the same. The helix angle of the intermediate large gear is greater than that of the intermediate small gear.

4. The powertrain according to claim 3, characterized in that, The helix angle of the intermediate large gear is greater than or equal to 26° and less than or equal to 30°, and the helix angle of the intermediate small gear is greater than or equal to 20° and less than or equal to 24°.

5. The powertrain according to claim 1, characterized in that, Along the axial direction of the motor shaft of the drive motor, the intermediate pinion, the intermediate gear, and the rotor of the drive motor are arranged in sequence, and the effective meshing width between the intermediate gear and the input wheel is smaller than the effective meshing width between the intermediate pinion and the output wheel.

6. The powertrain according to claim 5, characterized in that, The effective meshing width between the intermediate large gear and the input wheel is greater than or equal to 40 mm and less than or equal to 43 mm, and the effective meshing width between the intermediate small gear and the output wheel is greater than or equal to 46 mm and less than or equal to 50 mm.

7. The powertrain according to claim 1, characterized in that, The normal module of the intermediate large gear is smaller than the normal module of the intermediate small gear.

8. The powertrain according to claim 7, characterized in that, The normal module of the intermediate large gear is greater than or equal to 1.48 and less than or equal to 1.55, and the normal module of the intermediate small gear is greater than or equal to 2.55 and less than or equal to 2.

75.

9. The powertrain according to claim 1, characterized in that, The normal pressure angle of the large intermediate gear is smaller than that of the small intermediate gear.

10. The powertrain according to claim 9, characterized in that, The normal pressure angle of the large intermediate gear is greater than or equal to 15° and less than or equal to 18°, and the normal pressure angle of the small intermediate gear is greater than or equal to 20° and less than or equal to 23°.

11. The powertrain according to any one of claims 1-10, characterized in that, The axial overlap between the intermediate large gear and the input gear is greater than the axial overlap between the intermediate small gear and the output gear.

12. The powertrain according to claim 11, characterized in that, The axial overlap between the intermediate large gear and the input gear is greater than or equal to 3.9 and less than or equal to 4.1, and the axial overlap between the intermediate small gear and the output gear is greater than or equal to 1.95 and less than or equal to 2.

15.

13. The powertrain according to any one of claims 1-10, characterized in that, The reducer includes an input shaft and an output shaft. The input shaft is used to fix the input wheel and a motor shaft for driving the drive motor. The output shaft is used to fix the output wheel and drive the wheel, wherein: Along the arrangement direction of the input wheel and the intermediate large gear, the input shaft and the output shaft are arranged on both sides of the intermediate large gear.

14. The powertrain according to any one of claims 1-10, characterized in that, The powertrain housing includes a reducer cavity for accommodating the gear set. The cavity wall of the reducer cavity includes two sets of bearing grooves that are opposite each other along the axial direction of the powertrain. Each set of bearing grooves includes multiple bearing grooves, which are used to fix the outer rings of multiple bearings. The inner rings of the multiple bearings are used to fix the input shaft, output shaft, and intermediate shaft of the reducer.

15. An electric vehicle, characterized in that, The electric vehicle includes a frame, a power battery, and a powertrain as described in any one of claims 1-14, wherein the frame is used to fix the power battery and the powertrain, and the powertrain is used to drive the drive motor.

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