Double-speed reducer and automobile drive axle

Abstract

The application relates to a double-speed reducer, which comprises a driving assembly, a transmission assembly and a driving cylindrical gear, and a shift piece. The driving assembly comprises an input shaft, which can rotate around a first axis under the action of driving force. The transmission assembly and the driving cylindrical gear comprise a first transmission unit and a second transmission unit with different transmission ratios, and the driving cylindrical gear can rotate around the first axis under the driving of the first transmission unit and the second transmission unit. The shift piece is sleeved on the input shaft and can move along the first axis under the action of external force. The shift piece has a first state and a second state during the movement. The double-speed reducer can realize good reduction effect by transmitting torque to the driving cylindrical gear through the first transmission unit and the second transmission unit, and different transmission ratios can be selected according to actual conditions to adapt to driving in different road conditions, thereby enhancing the applicability of the double-speed reducer.

Description

Technical Field

[0001] This application relates to the field of automotive axles, and in particular to a dual-speed reducer and an automotive drive axle. Background Technology

[0002] With the development of the automotive industry, four-wheel drive mode has emerged. The engine output torque is distributed to the front and rear wheels in a fixed ratio. This drive mode can always have good off-road and handling performance. The motor torque is transmitted to the wheel ends of the vehicle's drive axle through the reducer and differential.

[0003] In related technologies, speed reduction is achieved by directly driving a driving spur gear and a driven spur gear with a motor. However, this meshing method results in relatively small speed reduction and cannot adjust the transmission ratio between the driving and driven spur gears according to actual conditions. Summary of the Invention

[0004] Therefore, it is necessary to provide a dual-speed reducer and a car drive axle that can be adjusted to different deceleration gears according to actual conditions to achieve a good deceleration effect.

[0005] This application provides a dual-speed reducer, comprising: a drive assembly for providing driving force, the drive assembly including an input shaft that can rotate around a first axis under the action of the driving force; a transmission assembly and a driving cylindrical gear, the transmission assembly including a first transmission unit and a second transmission unit with different transmission ratios, the first transmission unit and the second transmission unit being located at opposite ends of the driving cylindrical gear along a first direction parallel to the first axis, the driving cylindrical gear being able to rotate around the first axis under the drive of the first transmission unit and the second transmission unit; and a shifting member sleeved on the input shaft, the shifting member being able to move along the first axis under the action of an external force; wherein the shifting member has a first state and a second state during the movement; in the first state, the shifting member is driveably connected to the first transmission unit, enabling the input shaft to drive the first transmission unit to rotate around the first axis; in the second state, the shifting member is driveably connected to the second transmission unit, enabling the input shaft to drive the second transmission unit to rotate around the first axis.

[0006] By setting the first and second transmission units to have different transmission ratios, the position of the shifter on the input shaft can be adjusted according to road conditions during actual use, and a suitable transmission unit can be selected to obtain the desired deceleration effect. Compared with the method of the motor directly driving the driving spur gear to mesh with the driven spur gear for deceleration, this dual-speed reducer transmits torque to the driving spur gear through the first and second transmission units, first decelerating the driving spur gear, and then meshing the decelerated driving spur gear with the driven spur gear. This achieves a better deceleration effect, and different transmission ratios can be selected according to actual conditions to suit different road conditions, enhancing the applicability of the dual-speed reducer.

[0007] In one embodiment, the first transmission unit includes a first ring gear, a first planetary gear, and a first sun gear. The first sun gear meshes with the first planetary gear, and the first planetary gear meshes between the first sun gear and the first ring gear. The first sun gear and the first ring gear have a first transmission ratio. In the first state, the shifting member is connected to the first sun gear.

[0008] In one embodiment, the second transmission unit includes a second ring gear, a second planetary gear, and a second sun gear. The second sun gear meshes with the second planetary gear, and the second planetary gear meshes between the second sun gear and the second ring gear. There is a second transmission ratio between the second sun gear and the second ring gear. In the second state, the shifting member is connected to the second sun gear.

[0009] In one embodiment, the first transmission unit further includes a first planetary carrier, the second transmission unit further includes a second planetary carrier, and the transmission assembly further includes a planetary gear shaft, one end of which is connected to the first planetary carrier, and the other end of which is connected to the second planetary carrier after passing through the first planetary gear, the driving cylindrical gear and the second planetary gear.

[0010] In one embodiment, the dual-speed reducer further includes a housing, a first gear ring fixedly connected to the housing, and a second gear ring fixedly connected to the housing.

[0011] Another aspect of this application provides an automotive drive axle, the automotive drive axle including: a front axle assembly; a rear axle assembly including a two-speed reducer as described above; and a drive shaft, the front axle assembly being connected to the rear axle assembly via the drive shaft.

[0012] In one embodiment, the rear axle assembly further includes an inter-axle differential that is rotatable about a second axis, which is parallel to the first axis, under the drive of a two-speed reducer.

[0013] In one embodiment, the rear axle assembly includes two reducers disposed on both sides of the inter-axle differential along a second direction perpendicular to the first direction.

[0014] In one embodiment, the inter-shaft differential includes a driven cylindrical gear that is capable of moving about a second axis under the action of a dual-speed reducer, and the driven cylindrical gear meshes with the driving cylindrical gear in a second direction.

[0015] In one embodiment, the number of teeth on the driving cylindrical gear is less than the number of teeth on the driven cylindrical gear. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of a vehicle drive axle in some embodiments of this application.

[0017] Figure 2 This is a cross-sectional view of a dual-speed reducer in some embodiments of this application.

[0018] Figure 3 This is an exploded view of a dual-speed reducer in some embodiments of this application.

[0019] Figure 4 This is a cross-sectional view of the inter-shaft differential connecting to the second driving bevel gear in some embodiments of this application.

[0020] Figure 5 This is an exploded view of the inter-shaft differential connecting the second driving bevel gear in some embodiments of this application. Detailed Implementation

[0021] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0022] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0023] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0026] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0027] The drive axle of an automobile is located at the end of the vehicle's powertrain. It is used to transmit the power from the power system and distribute the power reasonably to different drive wheels. In addition, it also bears the vertical, longitudinal, and lateral forces acting between the road surface and the vehicle frame or body.

[0028] See Figure 1 , Figure 1A cross-sectional view of a vehicle drive axle according to some embodiments of this application is shown. In some embodiments, the vehicle drive axle includes a front axle assembly 100, a drive shaft 300, and a rear axle assembly 200. The front axle assembly 100 is connected to the rear axle assembly 200 via the drive shaft 300 to realize power transmission between the front and rear drive wheels.

[0029] The front axle assembly 100 is used to transmit forces in all directions between the vehicle frame and the front wheels, as well as the bending moments and torques generated therefrom, and is typically located at the front end of the vehicle. The front axle assembly 100 includes a first inter-wheel differential 110, a first drive bevel gear 120, and a first wheel-side reducer (not shown).

[0030] The first inter-wheel differential 110 is used to enable the front drive wheels to rotate at different speeds. The first inter-wheel differential 110 meshes with the first driving bevel gear 120 through the driven bevel gear, and is connected to the splined shaft of the half shaft through the splined hole 2 of the half shaft gear. The half shaft is connected to the first wheel-side reducer to realize the power transmission of the front drive wheels.

[0031] The first driving bevel gear 120 is used to transmit power between the drive shaft 300 and the first inter-wheel differential 110.

[0032] The first driving bevel gear 120 is equipped with a flange structure, which is bolted to the drive shaft 300.

[0033] The rear axle assembly 200 is used to transmit forces in all directions between the vehicle frame and the rear wheels, as well as the resulting bending moments and torques, and is typically located at the rear end of the vehicle. In this application, the rear axle assembly 200 is the driving axle, and the front axle assembly 100 is the driven axle.

[0034] In some embodiments, the rear axle assembly 200 includes a two-speed reducer 210, an inter-axle differential 220, a through shaft 230, a second inter-wheel differential 240, a second drive bevel gear 250, and a second wheel-side reducer (not shown). The operating mechanism and connection relationship of the second inter-wheel differential 240, the second drive bevel gear 250, and the second wheel-side reducer are the same as those in the front axle assembly 100 described above, and will not be repeated here.

[0035] The rear axle assembly 200 is an integrated design, which makes the transmission mechanism of the vehicle drive axle more compact, facilitates the reduction of the weight of the vehicle drive axle, achieves lightweight design, and reduces the cost of the vehicle drive axle, which is conducive to mass production and practical application.

[0036] The dual-speed reducer 210 provides power to the vehicle's drive axle on one hand, and enables the drive axle to have a suitable output speed on the other. The dual-speed reducer 210 can drive the inter-axle differential 220 to rotate around the second axis X2. The rotation of the inter-axle differential 220 drives the through shaft 230 to rotate, providing driving force to the front axle assembly 100, and drives the second drive bevel gear 250 to rotate, providing power to the rear axle drive wheels on the other hand.

[0037] One end of the through shaft 230 along the second axis X2 is connected to the inter-axle differential 220, and the other end is connected to the drive shaft 300, transmitting the power generated by the rear axle assembly 200 to the front axle assembly 100. The through shaft 230 is equipped with a flange structure, which is bolted to the drive shaft 300 to transmit the power generated by the dual-speed reducer 210 to the drive shaft 300.

[0038] The dual-speed reducer 210 provided in the embodiments of this application will be described in detail below.

[0039] See Figure 2 and Figure 3 , Figure 2 and Figure 3 A schematic diagram of a dual-speed reducer according to some embodiments of this application is shown. In some embodiments, the dual-speed reducer 210 includes a drive assembly 211, a drive spur gear 212, a transmission assembly, and a shifting element 215. The dual-speed reducer 210 reduces the rotational speed through the transmission ratio between the transmission assemblies and transmits torque to the inter-shaft differential 220.

[0040] The drive assembly 211, which provides driving force, includes a motor 2111 and an input shaft 2112. The motor 2111 provides power input to the vehicle's drive axle, generating power to drive the vehicle. Typically, the motor 2111 is used to convert electrical energy into mechanical energy and features a wide speed range, high starting torque, high backup power, high efficiency, and high reliability.

[0041] Combination Figure 1 The two dual-speed reducers 210 can use the same model of motor 2111, or two motors 2111, one large and one small. The larger motor 2111 operates under low-speed, high-torque conditions, while the smaller motor 2111 operates under high-speed, low-torque conditions, ensuring that the motor 2111 always operates within its own high-efficiency range during vehicle operation. Alternatively, motors 2111 of the same power can be used, with different high-efficiency ranges: one ensuring high efficiency at low speeds, and the other at high speeds. Depending on the operating conditions, a single motor 2111 can be used to ensure it always operates within its own high-efficiency range. Alternatively, both motors 2111 can be used simultaneously to ensure sufficient power or speed under all operating conditions, maximizing the efficiency of the motors 2111.

[0042] See Figure 2 and Figure 3 The input shaft 2112 is connected to the motor 2111 and is used to input power from the motor 2111. Under the driving force of the motor 2111, the input shaft 2112 can rotate around the first axis X1. Specifically, the input shaft 2112 is a splined shaft, and the motor 2111 is provided with a splined hole. The input shaft 2112 is connected to the motor 2111 through the splined shaft connecting to the splined hole. Generally, spline connections have uniform stress distribution, can withstand large loads, have good guiding properties, and are beneficial to the transmission of power from the motor 2111.

[0043] To ensure the long-term operation of the dual-speed reducer 210, a bearing 2113 is also provided between the motor 2111 and the input shaft 2112. The bearing 2113 reduces sliding resistance, power consumption, and wear between the motor 2111 and the input shaft 2112. The outer diameter of the bearing 2113 matches the bore diameter of the motor 2111, and the inner diameter of the bearing 2113 matches the shaft diameter of the input shaft 2112. The bearing 2113 can be a needle roller bearing, ball bearing, roller bearing, etc.

[0044] To ensure the relative position between the input shaft 2112 and the motor 2111 is fixed, and to fix the position of the bearing 2113, a first retaining ring 2114 and a second retaining ring 2115 are provided between the motor 2111 and the input shaft 2112. Specifically, the first retaining ring 2114 is used for axial limiting of the outer diameter of the bearing 2113, and the second retaining ring 2115 is used for axial limiting of the inner diameter of the bearing 2113. The arrangement of the first retaining ring 2114 and the second retaining ring 2115 achieves the fixation of the input shaft 2112 and the bearing 2113, ensuring stable power transmission.

[0045] The transmission assembly transmits power from the output shaft 2112 to drive the drive spur gear 212 to rotate around the first axis X1. The transmission assembly includes a first transmission unit 213 and a second transmission unit 214, located at opposite ends of the drive spur gear 212 along a first direction S1 parallel to the first axis X1. The first transmission unit 213 and the second transmission unit 214 have different transmission ratios. The transmission assembly first reduces speed through the drive spur gear 212, and then further reduces speed through the inter-shaft differential 220 via the drive spur gear 212, achieving a good deceleration effect. Different transmission ratios allow the dual-speed reducer 210 to have different deceleration gears. By switching between deceleration gears under different road conditions, a suitable deceleration effect can be obtained, ensuring the continuity of power during driving and adapting to different road conditions.

[0046] The shift component 215 is sleeved on the input shaft 2112. The center of the shift component 215 is provided with a spline hole. The input shaft 2112 is a spline shaft. The shift component 215 is sleeved on the input shaft 2112 through the spline shaft and spline hole. The spline connection ensures smooth power transmission between the input shaft 2112 and the shift component 215.

[0047] The shifting member 215 can move along the first axis X1 on the input shaft 2112 under the action of external force. The shifting member 215 has a first state and a second state during the movement. In the first state, the shifting member 215 is connected to the first transmission unit 213, so that the input shaft 2112 drives the first transmission unit 213 to rotate around the first axis X1. At this time, there is a first transmission ratio between the input shaft 2112 and the driving cylindrical gear 212. In the second state, the shifting member 215 is connected to the second transmission unit 214, so that the input shaft 2112 drives the second transmission unit 214 to rotate around the first axis X1. At this time, there is a second transmission ratio between the input shaft 2112 and the driving cylindrical gear 212.

[0048] In a feasible embodiment, the first transmission ratio is greater than the second transmission ratio. When the speed is low and the load is heavy, the shift member 215 is switched to the first state so that the input shaft 2112 and the driving cylindrical gear 212 have the first transmission ratio. When the speed is high and the load is light, the shift member 215 is switched to the second state so that the input shaft 2112 and the driving cylindrical gear 212 have the second transmission ratio.

[0049] In some embodiments, the first transmission unit 213 is disposed on the end of the driving cylindrical gear 212 on the first axis X1 near the motor 2111. The first transmission unit 213 includes a first sun gear 2131, a first planet gear 2132 and a first ring gear 2133. In the first state, the shift member 215 is connected to the first sun gear 2131 in a transmission manner. The first sun gear 2131 meshes with the first planet gear 2132, and the first planet gear 2132 meshes between the first sun gear 2131 and the first ring gear 2133.

[0050] The first sun gear 2131 has a splined hole at its center along the first axis X1, and part of the shift member 215 is configured as a splined shaft. The first sun gear 2131 can achieve a transmission connection with the shift member 215 through the splined shaft and splined hole. The splined connection ensures smooth power transmission between the shift member 215 and the first sun gear 2131.

[0051] In some embodiments, the second transmission unit 214 is disposed at the end of the driving cylindrical gear 212 on the first axis X1 away from the motor 2111, and the second transmission unit 214 and the first transmission unit 213 are arranged opposite to each other along the first axis X1. The second transmission unit 214 includes a second sun gear 2141, a second planet gear 2142, and a second ring gear 2143. In a second state, the second sun gear 2141 can drive the shifting member 215, and the second sun gear 2141 meshes with the second planet gear 2142, and the second planet gear 2142 meshes between the second sun gear 2141 and the second ring gear 2143. It should be noted that the number of the first planet gear 2142 and the second planet gear 2142 can be set according to actual needs.

[0052] The second sun gear 2141 has a splined hole at its center along the second axis X1, and part of the shift member 215 is configured as a splined shaft. The second sun gear 2141 can achieve a transmission connection with the shift member 215 through the splined shaft and splined hole. The splined connection ensures smooth power transmission between the shift member 215 and the second sun gear 2141.

[0053] In some embodiments, the first transmission unit 213 further includes a first planetary carrier 2134, the second transmission unit 214 further includes a second planetary carrier 2144, and the transmission assembly further includes planetary gear shafts 215. One end of the planetary gear shaft 215 is connected to the first planetary carrier 2134, and the other end is connected to the second planetary carrier 2144 after passing through the first planetary gear 2132, the driving spur gear 212, and the second planetary gear 2142. The planetary gear shaft 215 fixes the first planetary gear 2132 between the first planetary carrier 2134 and the driving spur gear 212, and the second planetary gear 2142 between the second planetary carrier 2144 and the driving spur gear 212. When the first planetary gear 2132 or the second planetary gear 2142 rotates, it can drive the first planetary carrier 2134 and the second planetary carrier 2144 to rotate, thereby driving the rotation of the driving spur gear 212. The number of planetary gear shafts 215 is the same as the number of first planetary gears 2132 and second planetary gears 2142.

[0054] The first planetary carrier 2134 and the second planetary carrier 2144 are provided with circumferential distribution holes, and the shaft diameters at both ends of the planetary gear shaft 215 are matched with the diameters of the distribution holes. To reduce wear between the planetary gear shaft 215 and the first planetary gear 2132, the driving cylindrical gear 212, and the second planetary gear 2142, bearings are provided between the planetary gear shaft 215 and each of the following: the inner diameter of the bearing is matched with the shaft diameter at the middle of the planetary gear shaft 215, and the outer diameter of the bearing is matched with the bore diameters of the first planetary gear 2132, the driving cylindrical gear 212, and the second planetary gear 2142, respectively.

[0055] To ensure the fixation of the first planetary carrier 2134 and the second planetary carrier 2144, a connecting hole is provided at the center of the first planetary carrier 2134 and the second planetary carrier 2144 along the first axis X1. A fastener passes through the connecting hole of the second planetary carrier 2144 and the connecting hole of the first planetary carrier 2134 to achieve the connection between the first planetary carrier 2134 and the second planetary carrier 2144. The fastener can be a bolt, and the connecting hole can be a threaded hole, achieving a threaded connection between the first planetary carrier 2134 and the second planetary carrier 2144 by connecting the bolt to the threaded hole.

[0056] To reduce wear when the first planetary carrier 2134 and the first gear ring 2133, and the second planetary carrier 2144 and the second gear ring 2143 rotate relative to each other, bearings are also provided between the first planetary carrier 2134 and the first gear ring 2133, and between the second planetary carrier 2144 and the second gear ring 2143. The inner diameter of the bearings is matched with the shaft diameter of the first planetary carrier 2134 and the second planetary carrier 2144, respectively, and the outer diameter of the bearings is consistent with the diameter of the mounting holes of the first gear ring 2133 and the second gear ring 2143, respectively.

[0057] The first transmission unit 213 is arranged in sequence along the first axis away from the motor, consisting of a first gear ring 2133, a first planetary carrier 2134, a first sun gear 2131, and a first planetary gear 2132. The second transmission unit 213 is arranged in sequence along the first axis away from the motor, consisting of a second sun gear 2141, a second planetary gear 2142, a second planetary carrier 2144, and a second gear ring 2133. To prevent the first sun gear 2131 and the first planetary gear 2132 from squeezing and colliding with the first planetary carrier 2134, the first sun gear 2131 and the first planetary gear 2132 from squeezing and colliding with the driving cylindrical gear 212, the second sun gear 2141 and the second planetary gear 2142 from squeezing and colliding with the first planetary carrier 2144, and the second sun gear 2141 and the second planetary gear 2142 from squeezing and colliding with the driving cylindrical gear 212, and to ensure the normal operation of the dual-speed reducer 210, gaskets are provided between the above components.

[0058] In some embodiments, the dual-speed reducer 210 further includes a housing (not shown), a first gear ring 2133 fixedly connected to the housing, and a second gear ring 2143 fixedly connected to the housing. The fixed first gear ring 2133 causes the first planetary gear 2132 to rotate, which in turn drives the first planetary carrier 2134 to rotate; the fixed second gear ring 2143 causes the second planetary gear 2142 to rotate, which in turn drives the second planetary carrier 2144 to rotate. At this time, the first transmission unit 213 takes the first sun gear 2131 as power input and the first planetary carrier 2134 as power output; the second transmission unit 214 takes the second sun gear 2141 as power input and the second planetary carrier 2144 as power output. The transmission ratio of the first transmission unit 213 is the ratio of the number of teeth on the first gear ring 2133 to the number of teeth on the first sun gear 2131 plus one; the transmission ratio of the second transmission unit 214 is the ratio of the number of teeth on the second gear ring 2143 to the number of teeth on the second sun gear 2141 plus one.

[0059] The specific working principle of the dual-speed reducer 210 is as follows: In the first state, the shifting component 215 is connected to the first sun gear 2131, which drives the first planetary gear 2132 to rotate. The first planetary gear 2132 drives the first planetary carrier 2134 and the second planetary carrier 2144 to rotate, and the first planetary carrier 2134 and the second planetary carrier 2144 drive the driving spur gear 212 to rotate along the first axis X1. In the second state, the shifting component 215 is connected to the second sun gear 2141, which drives the second planetary gear 2142 to rotate. The second planetary gear 2142 drives the first planetary carrier 2134 and the second planetary carrier 2144 to rotate, and the first planetary carrier 2134 and the second planetary carrier 2144 drive the driving spur gear 212 to rotate along the first axis X1. By changing the connection relationship of the shifting component 215 in different states, different transmission ratios are achieved between the input shaft 2112 and the driving spur gear 212, resulting in different reduction effects suitable for different road conditions. The dual-speed reducer 210 can achieve good deceleration effect and has a compact structure that saves space.

[0060] Combination Figure 1 The rear axle assembly 200 includes two dual-speed reducers 210. The two dual-speed reducers 210 are positioned on either side of the inter-axle differential 220 along a second direction S2, perpendicular to the first direction S1. The arrangement of the two dual-speed reducers 210 allows them to drive simultaneously, ensuring sufficient power or speed under various operating conditions, including normal driving and hill climbing. Simultaneously, the arrangement of the two dual-speed reducers 210 reduces the radial bending moment on the gears, thereby reducing their weight.

[0061] In some embodiments, the two dual-speed reducers 210 are symmetrically arranged relative to the central axis of the inter-axle differential 220 in the first direction S1. This symmetrical arrangement of the two dual-speed reducers 210 facilitates uniform power transmission, balances the weight of the vehicle drive axle on both sides in the second direction S2, and improves the stability of the drive axle. In a further embodiment, the first axis X1 is parallel to the second axis X2, which facilitates power transmission through the dual-speed reducers 210 while avoiding the generation of additional torque, ensuring efficient power transmission and the normal operation of the inter-axle differential 220.

[0062] The inter-axle differential 220 is used to eliminate the slippage of the drive wheels of the front axle assembly 100 and the rear axle assembly 200, allowing the front axle assembly 100 and the rear axle assembly 200 to have different input angular velocities. At the same time, the inter-axle differential 220 distributes power to the through shaft 230 and the second driving bevel gear 250, realizing the power distribution and differential between the front axle assembly 100 and the rear axle assembly 200. There is no need to set up a separate transfer case, reducing the weight of the vehicle drive axle.

[0063] The inter-axle differential 220 provided in the embodiments of this application will be described in detail below.

[0064] See Figure 4 and Figure 5 , Figure 4 and Figure 5 A schematic diagram of the inter-shaft differential connecting to a second driving bevel gear in some embodiments of this application is shown.

[0065] In some embodiments, the inter-shaft differential 220 includes a driven cylindrical gear 221, a planetary carrier assembly 222, a ring gear assembly 223, and a planetary gear set 224. The power output from the dual-speed reducer 210 is sequentially transmitted to the first output component and the second output component via the driven cylindrical gear 221, the planetary carrier assembly 222, the planetary gear set 224, and the ring gear assembly 223, respectively. Both the ring gear assembly 223 and the planetary gear set 224 employ cylindrical gear structures, with each cylindrical gear arranged along the second axis X2. This avoids the inter-shaft force component caused by bevel gears and also avoids increasing the inter-shaft arrangement space, making the internal structure of the inter-shaft differential 220 more compact and improving its reliability.

[0066] Combination Figure 1 The through shaft 230 is configured as the first output component, the second drive bevel gear 250 is configured as the second output component, and the inter-shaft differential 220 distributes power to the first output component 230 and the second output component 250, thereby realizing the power distribution between the front axle assembly 100 and the rear axle assembly 200.

[0067] Driven cylindrical gear 221 can rotate around the second axis X2 under the action of dual-speed reducer 210, combined with Figure 1 and Figure 2The driven cylindrical gear 221 meshes with the driving cylindrical gear 212 to transmit power and torque. The use of two driving cylindrical gears 212 to jointly drive the driven cylindrical gear 221 reduces the radial bending moment of the gear pair. The two driving cylindrical gears 212 mesh with the driven cylindrical gear 221 along the second direction S2, making the structure of the vehicle's drive axle more compact.

[0068] In some embodiments, the number of teeth on the driving cylindrical gear 212 is less than the number of teeth on the driven cylindrical gear 221, making the transmission ratio between the dual-speed reducer 210 and the inter-shaft differential 220 greater than 1, thereby enabling the inter-shaft differential 220 to have a reduction function. Compared with the conventional single driving cylindrical gear 212 driving the driven cylindrical gear 221, the dual driving cylindrical gears 212 jointly driving the driven cylindrical gear 221 can achieve greater reduction, ensuring the reduction effect of the inter-shaft differential 220.

[0069] See Figure 4 and Figure 5 The planetary carrier assembly 222 is connected to the driven cylindrical gear 221 along the second axis X2 for transmitting power to the driven cylindrical gear 221. The planetary carrier assembly 222 provides a mounting position for the planetary gear set 224, and transmits power from the driven cylindrical gear 221 to the planetary gear set 224 through the planetary carrier assembly 222.

[0070] In some embodiments, the planetary carrier assembly 222 includes a third planetary carrier 2221 and a fourth planetary carrier 2222. The third planetary carrier 2221 and the fourth planetary carrier 2222 are respectively disposed at both ends of the driven cylindrical gear 221 on the second axis X2. The third planetary carrier 2221 connects the driven cylindrical gear 221 and the fourth planetary carrier 2222 along the second axis X2. Power transmission is achieved by connecting the driven cylindrical gear 221 and the fourth planetary carrier 2222 through the third planetary carrier 2221. At the same time, being disposed at both ends of the driven cylindrical gear 221 on the second axis X2 allows the planetary gear set 224 to be connected to the driven cylindrical gear 221.

[0071] In a specific embodiment, the driven cylindrical gear 221 has a splined hole at its center, and the third planetary carrier 2221 has a splined shaft at its center. The splined shaft and the splined hole are arranged along the second axis X2 and are located on the same axis. The third planetary carrier 2221 is connected to the driven cylindrical gear 221 through the splined shaft and splined hole. The splined connection ensures that the third planetary carrier 2221 is subjected to uniform force and has good guiding properties, which is beneficial to the power transmission of the driven cylindrical gear 221.

[0072] To fix the relative position of the driven cylindrical gear 221 and the third planetary carrier 2221, the inter-shaft differential 220 is provided with a third retaining ring 225. The third retaining ring 225 is disposed on the splined shaft on the side of the third planetary carrier 2221 that passes through the splined hole, thereby achieving axial limiting of the driven cylindrical gear 221.

[0073] The third planetary carrier 2221 and the fourth planetary carrier 2222 are connected by fasteners 226. The third planetary carrier 2221 has connecting holes on the second axis X2 for the fasteners 226 to pass through. At least part of the connecting holes are located in the splined shaft. The fasteners 226 pass sequentially through the third planetary carrier 2221, the driven cylindrical gear 221, and the fourth planetary carrier 2222, thus achieving a fixed connection between the third planetary carrier 2221 and the fourth planetary carrier 2222. Specifically, the fasteners 226 are bolts, with the bolt's shaft diameter matching the connecting hole 251 of the third planetary carrier 2221. The fourth planetary carrier 2222 has threaded holes matching the thread diameter of the bolts, achieving a threaded connection between the third planetary carrier 2221 and the fourth planetary carrier 2222. The threaded connection structure is simple, easy to install and disassemble, and facilitates the installation, inspection, and maintenance of the inter-shaft differential 220.

[0074] The ring gear assembly 223 is used to output the power transmitted by the planetary gear set 224 to the first output component 230 and the second output component 250 respectively, realizing the power distribution of the dual-speed reducer 210 to the front axle assembly 100 and the rear axle assembly 200. The ring gear assembly 223 also enables the planetary gear set 224 to revolve around the ring gear assembly 223, allowing the planetary gear set 224 to transmit power to the ring gear assembly 223, realizing the power transmission within the inter-shaft differential 220.

[0075] In some embodiments, the gear ring assembly 223 includes a third gear ring 2231 and a fourth gear ring 2232, which are disposed at both ends of the planetary carrier assembly 222 on the second axis X2. The third gear ring 2231 is connected to a first output member, and the fourth gear ring 2232 is connected to a second output member. Both the third gear ring 2231 and the fourth gear ring 2232 are internal gear rings, allowing the planetary gear set 224 to move around the third gear ring 2231 and the fourth gear ring 2232. Further, the inner walls of the third gear ring 2231 and the fourth gear ring 2232 are provided with circumferentially distributed cylindrical teeth for meshing with the planetary gear set 224, which has a cylindrical gear structure.

[0076] Specifically, in this embodiment, the third ring gear 2231 is disposed on the third planetary carrier 2221 on the second axis X2, away from the driven cylindrical gear 221, and the fourth ring gear 2232 is disposed on the fourth planetary carrier 2222 on the second axis X2, away from the driven cylindrical gear 221. The third planetary carrier 2221 is connected to and housed within the third ring gear 2231, and the fourth planetary carrier 2222 is connected to and housed within the fourth ring gear 2232.

[0077] To reduce wear between the third gear ring 2231 and the third planetary carrier 2221, and between the fourth gear ring 2232 and the fourth planetary carrier 2222, the third gear ring 2231 and the third planetary carrier 2221 are connected by bearings, and the fourth gear ring 2232 and the fourth planetary carrier 2222 are also connected by bearings. The bearing arrangement results in low sliding resistance and low power consumption between the gear ring assembly 223 and the planetary carrier assembly 222.

[0078] Combination Figure 1 The center of the third gear ring 2231 is provided with a splined hole at the end opposite to the driven cylindrical gear 221 on the second axis X2. The through shaft 230 is at least partially configured as a splined shaft on the second axis X2. The connection between the third gear ring 2231 and the through shaft 230 is realized through the splined shaft and the splined hole, ensuring stable power transmission. Power is transmitted to the drive wheels of the front axle assembly 100 through the through shaft 230 and the drive shaft 300.

[0079] The center of the fourth gear ring 2232 is provided with a spline hole on the second axis X2 away from the driven cylindrical gear 221. The second driving bevel gear 250 is at least partially provided as a spline shaft on the second axis X2. The connection between the fourth gear ring 2232 and the second driving bevel gear 250 is realized through the spline shaft and the spline hole, ensuring stable power transmission. The power is transmitted to the drive wheel of the rear axle assembly through the second driving bevel gear 250.

[0080] To fix the relative position of the fourth gear ring 2232 and the second driving bevel gear 250, the fourth gear ring 2232 and the second driving bevel gear 250 are also connected by a fastener 227. The center of the second driving bevel gear 250 is provided with a connecting hole 251 on the second axis X2 for the fastener 227 to pass through. The fastener 227 passes through the connecting hole 251 and connects to the threaded hole 2232c of the fourth gear ring 2232, thus realizing the connection and fixation of the fourth gear ring 2232 and the second driving bevel gear 250. Specifically, the fastener 227 is a bolt, and the bolt's shaft diameter matches the diameter of the connecting hole 251 of the second driving bevel gear 250. The threaded connection structure is simple, easy to disassemble and assemble, and convenient for installation and subsequent inspection and maintenance.

[0081] See Figure 4 and Figure 5 The planetary gear set 224 is used to transmit power from the planetary carrier set 222 to the ring gear set 223. The planetary carrier set 222 can drive the planetary gear set 224 to rotate, and the planetary gear set can drive the ring gear set 223 to rotate.

[0082] In some embodiments, the planetary gear set 224 includes a third planetary gear 2241 and a fourth planetary gear 2242. The third planetary gear 2241 and the fourth planetary gear 2242 are respectively disposed along the second axis X2 on the driven cylindrical gear 221. Both the third planetary gear 2241 and the fourth planetary gear 2242 are cylindrical gears. The third planetary gear 2241 meshes with the third ring gear 2231 and the fourth planetary gear 2242. Specifically, one end of the third planetary gear 2241 on the second axis X2 meshes with the third ring gear 2231, and the other end of the third planetary gear 2241 on the second axis X2 meshes with the fourth planetary gear 2242 and the fourth ring gear 2232. The fourth planetary gear 2242 meshes with the fourth ring gear 2232. The third planetary gear 2241 can drive the third ring gear 2231 to rotate, outputting power to the first output member 230. The fourth planetary gear 2242 can drive the fourth ring gear 2232 to rotate, outputting power to the second output member 250.

[0083] In some embodiments, the third planetary carrier 2221 and the fourth planetary carrier 2222 are circumferentially spaced with evenly distributed holes. A third planetary gear 2241 passes through these holes and connects to the third planetary carrier 2221 and the fourth planetary carrier 2222 along the second axis X2. A fourth planetary gear 2242 also passes through these holes and connects to the third planetary carrier 2221 and the fourth planetary carrier 2222 along the second axis X2. The evenly distributed holes allow the planetary gear set 224 to pass through, thus connecting the planetary gear set 224 to the planetary carrier set 222. The arrangement of the evenly distributed holes is based on the distribution of the planetary gear set 224. The connection between the planetary gear set 224 and the planetary carrier set 222 is achieved through the evenly distributed holes, enabling the planetary carrier set 222 to drive the planetary gear set 224 to rotate.

[0084] The planetary gear set 224 allows the power of the planetary carrier set 222 to be distributed to the third ring gear 2231 and the fourth ring gear 2232, enabling the inter-axle differential 220 to achieve power distribution. At the same time, the different rotation states of the planetary gear set 224 enable the inter-axle differential 220 to perform differential function for the front axle assembly 100 and the rear axle assembly 200.

[0085] The third planetary gear 2241 meshes with the third ring gear 2231, and the fourth planetary gear 2242 meshes with the fourth ring gear 2232. When the first output component 230 and the second output component 250 rotate at the same speed, the third planetary gear 2241 revolves around the third ring gear 2231, and the fourth planetary gear 2242 revolves around the fourth ring gear 2232. When the first output component 230 and the second output component 250 rotate at different speeds, the third planetary gear 2241 and the fourth planetary gear 2242 rotate in different directions while revolving around each other, so that the speeds of the third ring gear 2231 and the fourth ring gear 2232 are different, thereby eliminating the slippage phenomenon of each axle drive wheel and realizing the differential function of the inter-axle differential 220.

[0086] In some embodiments, the third planetary gear 2241 is provided with a first transmission member 2241a and a second transmission member 2241b on both sides of the second axis X2. The first transmission member 2241a and the second transmission member 2241b are both cylindrical gears. The first transmission member 2241a and the second transmission member 2241b are respectively disposed at both ends of the driven cylindrical gear 221 on the second axis X2. The first transmission member 2241a is used to mesh with the third gear ring 2231, and the second transmission member 2241b is used to mesh with the fourth planetary gear 2242.

[0087] The third planetary gear 2241 meshes with the third ring gear 2231 and the fourth planetary gear 2242 respectively through the first transmission component 2241a and the second transmission component 2241b, thereby transmitting power from the third planetary gear 2241 to the third ring gear 2231, and from the fourth planetary gear 2242 to the fourth ring gear 2232, thus transmitting power from the planetary gear set 224 to the ring gear set 223, and further enabling the inter-shaft differential 220 to distribute power to the first output component 230 and the second output component 250.

[0088] In some embodiments, to connect the first transmission member 2241a and the second transmission member 2241b, the third planetary gear 2241 further includes a planetary gear shaft 2241c. The planetary gear shaft 2241c passes through the first transmission member 2241a, the second transmission member 2241b, and the driven cylindrical gear 221 along the second axis X2. The two opposite ends of the planetary gear shaft 2241c on the second axis X2 pass through evenly distributed holes and connect to the third planetary carrier 2221 and the fourth planetary carrier 2222. Specifically, the two ends of the planetary gear shaft 2241c on the second axis X2 are respectively connected to the third planetary carrier 2221 and the fourth planetary carrier 2222. The shaft diameters at both ends of the planetary gear shaft 2241c match the diameters of the evenly distributed holes in the third planetary carrier 2221 and the fourth planetary carrier 2222, and the shaft diameter at the middle of the planetary gear shaft 2241c matches the diameters of the holes in the first transmission member 2241a and the second transmission member 2241b. The planetary gear shaft 2241c connects the third planetary gear 2241 and the planetary carrier 222, so that the power of the planetary carrier 222 can be transmitted to the third planetary gear 2241, driving the third planetary gear 2241 to rotate in the third gear ring 2231.

[0089] In some embodiments, the third planetary gear 2241 further includes a bearing 2241d, which passes through the planetary gear shaft 2241c and is disposed on the second axis X2 between the first transmission member 2241a and the second transmission member 2241b. The driven cylindrical gear 221 is connected to the third planetary gear 2241 via the bearing 2241d. The bearing 2241d reduces wear on the driven cylindrical gear 221 from the planetary gear shaft 2241c, thereby reducing power loss in the inter-shaft differential 220. The outer diameter of the bearing 2241d matches the diameter of the mating hole of the driven cylindrical gear 221, and the inner diameter matches the shaft diameter at the middle of the planetary gear shaft 2241c. The bearing 2241d is a needle roller bearing, which has low frictional resistance, low power consumption, high mechanical efficiency, low wear, and long service life. In other embodiments, the bearing 2241d can also be a ball bearing, roller bearing, etc.

[0090] In some embodiments, a third transmission member 2242a is provided on one side of the fourth planetary gear 2242 on the second axis X2. The third transmission member 2242a is disposed at one end of the fourth planetary gear 2242 on the second axis X2 and is used to mesh with the third planetary gear 2241 and the fourth ring gear 2232. The fourth planetary gear 2242 meshes with the cylindrical tooth hole 2232a of the fourth ring gear 2232 through the third transmission member 2242a, thereby transmitting power to the fourth ring gear 2232 and then to the second output member 250. The third transmission member 2242a meshes with a second transmission member 2241b at one end of the third planetary gear 2241. When the rotational speeds of the third ring gear 2231 and the fourth ring gear 2232 are inconsistent, the third planetary gear 2241 and the fourth planetary gear 2242 can rotate around different preset directions, realizing the differential function of the inter-shaft differential 220. It should be noted that the first transmission component 2241a, the second transmission component 2241b, and the third transmission component 2242a are set according to actual needs, and their specifications such as the number of teeth and tooth pitch can be the same or different.

[0091] Furthermore, in some embodiments, to achieve the connection between the fourth planetary gear 2241 and the planetary carrier assembly 222, the fourth planetary gear 2242 further includes a planetary gear shaft 2242b. The planetary gear shaft 2242b passes through the third transmission member 2242a and the driven cylindrical gear 221 along the second axis X2. The two ends of the planetary gear shaft 2242b on the second axis X2 are connected to the planetary carrier assembly 222. Specifically, the two opposite ends of the planetary gear shaft 2242b on the second axis X2 are respectively connected to the third planetary carrier 2221 and the fourth planetary carrier 2222. The shaft diameters at both ends of the planetary gear shaft 2242b match the size of the evenly distributed holes of the third planetary carrier 2221 and the fourth planetary carrier 2222, and the shaft diameter at the middle of the planetary gear shaft 2242b matches the diameter of the hole in the third transmission member 2242a. The planetary gear shaft 2242b is configured to connect the fourth planetary gear 2242 and the third planetary carrier 2221, as well as the fourth planetary gear 2242 and the fourth planetary carrier 2222, so that the power of the planetary carrier assembly 222 can be transmitted to the fourth planetary gear 2242, driving the fourth planetary gear 2242 to rotate in the fourth gear ring 2232.

[0092] In some embodiments, see Figure 1 and Figure 5 In one embodiment, the first output member 230 and the second output member 250 are arranged along a second axis X2, and the central axes of the first output member 230, the second output member 250, and the inter-axle differential 220 coincide. Specifically, the through shaft 230 and the second drive bevel gear 250 are arranged along the second axis X2, and the central axes of the through shaft 230 and the second drive bevel gear 250 are on the same axis. This arrangement makes the structure of the vehicle drive axle compact, facilitates direct power transmission, and avoids additional power loss. The coaxial arrangement saves the layout space of the front axle assembly 100 and the rear axle assembly 200, reduces the overall weight of the vehicle drive axle, and improves transmission efficiency.

[0093] In some embodiments, when the first output member 230 and the second output member 250 are outputting, the third planetary gear 2241 and the fourth planetary gear 2242 have a first rotation state and a second rotation state. In the first rotation state, the first output member 230 and the second output member 250 have the same speed, the third gear ring 2231 and the fourth gear ring 2232 rotate at the same speed, the third planetary gear 2241 revolves around the third gear ring 2231 and the fourth gear ring 2232, and the fourth planetary gear 2242 revolves around the fourth gear ring 2232. In the second rotation state, the first output member 230 and the second output member 250 have different speeds, the third gear ring 2231 and the fourth gear ring 2232 rotate at different speeds, the third planetary gear 2241 revolves around the third gear ring 2231 and the fourth gear ring 2232 while rotating in a preset direction, and the fourth planetary gear 2242 revolves around the fourth gear ring 2232 while rotating in a direction opposite to the preset direction.

[0094] Specifically, the first rotational state is the state when the car is running normally, there is no speed difference between the third ring gear 2231 and the fourth ring gear 2232, the third planetary gear 2241 revolves around the third ring gear 2231, and the fourth planetary gear 2242 revolves around the fourth ring gear 2232.

[0095] The second rotational state is the state of the car when it is turning or slipping on the road. There is a speed difference between the third ring gear 2231 and the fourth ring gear 2232. The third planetary gear 2241 revolves around the third ring gear 2231 and rotates on its own axis in a preset direction. The fourth planetary gear 2242 revolves around the fourth ring gear 2232 and rotates on its own axis in a direction opposite to the preset direction. The rotation of the third planetary gear 2241 and the fourth planetary gear 2242 drives the third ring gear 2231 and the fourth ring gear 2232 to rotate in opposite directions, thereby realizing the differential function of the inter-axle differential 220. In a feasible embodiment, the third gear ring 2231 rotates in the forward direction, the third planetary gear 2241 meshing with the third gear ring 2231 rotates in the forward direction, the fourth planetary gear 2242 meshing with the third gear ring 2231 rotates in the reverse direction, and the fourth gear ring 2232 meshing with the fourth planetary gear 2242 rotates in the reverse direction. The rotation directions of the third gear ring 2231 and the fourth gear ring 2232 are opposite, so that the third gear ring 2231 and the fourth gear ring 2232 have a speed difference.

[0096] In actual use, the power generated by the motor 211 drives the input shaft 212 to rotate, which in turn drives the shifting component 215 to rotate. When the vehicle is traveling at low speed with a heavy load, the shifting component 215 drives the first transmission unit 213 to rotate, which in turn drives the driving spur gear 212 to rotate. When the vehicle is traveling at high speed with a light load, the shifting component 215 drives the second transmission unit 214 to rotate, which in turn drives the driving spur gear 212 to rotate. The driving spur gear 212 then drives the driven spur gear 221 to rotate, which in turn drives the third planetary carrier 222. The rotation of the third planetary carrier 2221 and the fourth planetary carrier 2222 drives the third planetary gear 2241 to rotate around the third ring gear 2231 and the fourth planetary gear 2242 to rotate around the fourth ring gear 2232. The rotation of the third ring gear 2231 drives the through shaft 230 to rotate, and the rotation of the through shaft 230 drives the drive shaft 300 to rotate, thereby transmitting power to the front axle assembly 100 and the drive wheel of the front axle assembly 100. The rotation of the fourth ring gear 2232 drives the second active bevel gear 250 to rotate, thereby transmitting power to the drive wheel of the rear axle assembly 200.

[0097] When the car turns or slips, the third ring gear 2231 and the fourth ring gear 2232 generate a speed difference, and the corresponding third planetary gear 2241 and the fourth planetary gear 2242 rotate in opposite directions. This speed difference, which is adapted to the third ring gear 2231 and the fourth ring gear 2232, eliminates the slippage of the drive wheels of the front axle assembly 100 and the rear axle assembly 200, and allows the front axle assembly 100 and the rear axle assembly 200 to have different input angular velocities.

[0098] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A two-speed reduction gear, characterized in that, The double-speed reducer comprises: a driving assembly for providing a driving force; the driving assembly comprises an input shaft capable of rotating about a first axis under the action of the driving force; a transmission assembly and a driving cylindrical gear; the transmission assembly comprises a first transmission unit and a second transmission unit with different transmission ratios; the first transmission unit and the second transmission unit are located at two ends of the driving cylindrical gear in a first direction, the first direction and the first axis are parallel to each other, and the driving cylindrical gear is capable of rotating about the first axis under the drive of the first transmission unit and the second transmission unit; and a shift piece sleeved on the input shaft, the shift piece being capable of moving along the first axis under the action of an external force; wherein the shift piece has a first state and a second state during movement; in the first state, the shift piece is in transmission connection with the first transmission unit, so that the input shaft can drive the first transmission unit to rotate about the first axis; in the second state, the shift piece is in transmission connection with the second transmission unit, so that the input shaft can drive the second transmission unit to rotate about the first axis; the first transmission unit and the second transmission unit are both planetary gear mechanisms; the first transmission unit comprises a first planet carrier, the second transmission unit comprises a second planet carrier, and the transmission assembly comprises a planet shaft, one end of the planet shaft being connected to the first planet carrier and the other end of the planet shaft being connected to the second planet carrier via passing through the first planetary gear, the driving cylindrical gear and the second planetary gear.

2. The two-speed reduction gear according to claim 1, characterized in that the first transmission unit comprises a first ring gear, a first planetary gear and a first sun gear, the first sun gear meshes with the first planetary gear, and the first planetary gear is meshed between the first sun gear and the first ring gear; in the first state, the shift piece is in transmission connection with the first sun gear.

3. The two-speed reduction gear of claim 2, wherein the second transmission unit comprises a second ring gear, a second planetary gear and a second sun gear, the second sun gear meshes with the second planetary gear, and the second planetary gear is meshed between the second sun gear and the second ring gear; in the second state, the shift piece is in transmission connection with the second sun gear.

4. The two-speed reduction gear of claim 3, wherein the first sun gear and the second sun gear are both provided with spline holes along the center of the first axis, part of the shift piece is provided as a spline shaft, and the first sun gear and the second sun gear can be in transmission connection with the shift piece by combining the spline shaft with the spline hole.

5. Double reduction gear according to claim 3 or 4, characterized in that The double-speed reducer further comprises a housing, the first ring gear is fixedly connected with the housing, and the second ring gear is fixedly connected with the housing.

6. An automotive drive axle characterized by The automobile drive axle comprises: a front axle assembly; a rear axle assembly, the rear axle assembly comprising the double-speed reducer according to any one of claims 1-5; and a transmission shaft, the front axle assembly being connected to the rear axle assembly through the transmission shaft.

7. The automotive drive axle of claim 6, wherein, The rear axle assembly further comprises an inter-axle differential, the inter-axle differential being capable of rotating about a second axis under the drive of the double-speed reducer, the second axis being parallel to the first axis.

8. The automotive drive axle of claim 7, wherein, The rear axle assembly includes two reducers, which are arranged on both sides of the interaxle differential along a second direction; The first direction and the second direction are perpendicular to each other.

9. The automotive drive axle according to claim 7 or 8, characterized in that The interaxle differential includes a driven cylindrical gear capable of moving around the second axis under the action of the double-speed reducer, and the driven cylindrical gear is engaged with the driving cylindrical gear along a second direction. The first direction and the second direction are perpendicular to each other.

10. The automotive drive axle of claim 9, wherein, The number of teeth of the driving cylindrical gear is less than the number of teeth of the driven cylindrical gear.

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