Multi-gear speed reducer, electric drive device and electric drive axle assembly

Abstract

The utility model relates to a multi-gear speed reducer, an electric drive device and an electric drive axle assembly, the multi-gear speed reducer comprises a first-stage planetary speed reducing mechanism, a second-stage planetary speed reducing mechanism, a third-stage planetary speed reducing mechanism, a fourth-stage planetary speed reducing mechanism, a fourth-stage planetary speed reducing mechanism and a fifth-stage planetary speed reducing mechanism, the second-stage gear ring is selectively connected with the first-stage planet carrier or the axle housing through a gear shifting mechanism so as to limit relative rotation of the second-stage gear ring and the first-stage planet carrier or the axle housing; the transmission mechanism is used for transmitting the power to the second-stage gear ring or limiting the rotation of the first-stage gear ring; wherein the two first-stage sun gears in the two speed reduction units are coaxial, the first-stage sun gear of one speed reduction unit is used for being connected with a power source, the first-stage planet carrier of the speed reduction unit is fixed to the first-stage sun gear of the other speed reduction unit, and the first-stage planet carrier of the other speed reduction unit is used for outputting power. Power output by the power source can be output in a speed reduction mode according to multiple different speed reduction ratios, namely, power output of multiple gears is achieved, and therefore the multi-gear requirement when a vehicle runs under the complex road condition is met.

Description

Technical Field

[0001] The utility model relates to the technical field of electric drive systems, and particularly relates to a multi-speed reducer, an electric drive device and an electric drive axle assembly. Background Art

[0002] An electric drive axle belongs to a type of drive axle. The electric drive axle integrates a motor onto the axle to achieve functions such as integration and high efficiency. With the development of new energy vehicles, the technology of electric drive axles is also developing rapidly.

[0003] The transmission system of an electric drive axle is an important part of the electric drive axle. It reduces the speed and increases the torque of the power from the motor and then outputs it, enabling the electric drive axle to have sufficient traction and high efficiency. In related technologies, the transmission systems of some electric drive axles adopt a two-speed reducer with an adjustable reduction ratio, which can achieve power output in two gears, thereby meeting the requirements of the vehicle for low-speed high torque and higher vehicle speeds. However, facing increasingly complex road conditions, the requirements for electric drive axles are also getting higher and higher, and two gears can no longer meet the driving requirements of the vehicle. Summary of the Utility Model

[0004] Based on the above description, the utility model provides a multi-speed reducer, an electric drive device and an electric drive axle assembly to meet the multi-gear requirements of the vehicle when driving on complex road conditions.

[0005] The technical solution for the utility model to solve the above technical problems is as follows:

[0006] In the first aspect, the present application provides a multi-speed reducer, and the technical solution adopted is as follows:

[0007] A multi-speed reducer includes two reduction units, and the reduction unit includes:

[0008] A first-stage planetary reduction mechanism, which is used to be connected to the axle housing and includes a first-stage sun gear, first-stage planet gears, a first-stage planet carrier, and a first-stage ring gear. The first-stage ring gear coaxially surrounds the first-stage sun gear and can rotate relative to the axle housing around its own axis. The first-stage planet carrier can rotate relative to the axle housing around the axis of the first-stage sun gear. The first-stage planet gears are located between the first-stage sun gear and the first-stage ring gear and are connected to the first-stage planet carrier. The first-stage planet gears mesh with the first-stage sun gear and the first-stage ring gear, and the first-stage planet gears can rotate around their own axes and rotate with the first-stage planet carrier;

[0009] A second-stage ring gear, which is used to be connected to the axle housing. The second-stage ring gear coaxially surrounds the first-stage ring gear and can rotate relative to the axle housing around its own axis. The second-stage ring gear can be selectively connected to the first-stage planet carrier or the axle housing through a shifting mechanism to limit the relative rotation between the second-stage ring gear and the first-stage planet carrier or the axle housing;

[0010] A transmission mechanism, which connects the first-stage gear ring and the second-stage gear ring. When the first-stage gear ring rotates, power is transmitted to the second-stage gear ring through the transmission mechanism after deceleration, and the rotation directions of the first-stage gear ring and the second-stage gear ring are opposite. When the second-stage gear ring is fixedly connected to the axle housing through a shifting mechanism, the second-stage gear ring restricts the rotation of the first-stage gear ring through the transmission mechanism;

[0011] Among them, the two first-stage sun gears in the two reduction units are coaxial. One of the first-stage sun gears in the reduction unit is used to connect to a power source, the first-stage planet carrier of this reduction unit is fixed to the first-stage sun gear of the other reduction unit, and the first-stage planet carrier of the other reduction unit is used to output power.

[0012] Preferably, the transmission mechanism includes:

[0013] A second-stage sun gear, which is arranged between the second-stage gear ring and the first-stage gear ring and is coaxially and fixedly connected to the first-stage gear ring;

[0014] Second-stage planet gears, which are arranged between the second-stage sun gear and the second-stage gear ring and mesh with the second-stage sun gear and the second-stage gear ring;

[0015] A second-stage planet carrier, which is used to be fixed on the axle housing, and the second-stage planet gears are connected to the second-stage planet carrier and can rotate around their own axes.

[0016] Preferably, in each reduction unit, the second-stage gear ring can be selectively connected to the first-stage planet carrier or the second-stage planet carrier through a shifting mechanism to restrict the relative rotation between the second-stage gear ring and the first-stage planet carrier or the second-stage planet carrier.

[0017] Preferably, the shifting mechanism includes:

[0018] A first fixed engagement sleeve, which is coaxial with the first-stage sun gear and fixed to the first-stage planet carrier;

[0019] A second fixed engagement sleeve, which is coaxial with the first-stage sun gear and fixed to the axle housing;

[0020] A sliding engagement sleeve, which is coaxial with the second-stage gear ring and is connected to the second-stage gear ring through a spline. The sliding engagement sleeve can move axially relative to the axle housing, and the sliding engagement sleeve can move to engage with the first fixed engagement sleeve or the second fixed engagement sleeve.

[0021] Preferably, the sliding engagement sleeve can move to disengage from the first fixed engagement sleeve and the second fixed engagement sleeve.

[0022] In a second aspect, the present application provides an electric drive device, including:

[0023] The multi-speed reducer described in the first aspect above;

[0024] A motor, the output shaft of which is coaxially fixed with the first-stage sun gear for connecting the power source.

[0025] Preferably, it further includes a differential. The first-stage planet carrier for outputting power is connected to the input end of the differential, and the output end of the differential is used to connect the left and right half shafts, so as to transmit the power output by the first-stage planet carrier to the left and right half shafts through the differential.

[0026] In a third aspect, the present application provides an electric drive axle assembly, including:

[0027] A bridge housing;

[0028] The electric drive device described in the second aspect above, which is arranged inside the bridge housing;

[0029] Two half shafts arranged coaxially, the half shafts are rotatably connected to the bridge housing, and the two half shafts are respectively connected to the two output ends of the differential.

[0030] Compared with the prior art, the technical solution of the present application has at least the following beneficial technical effects:

[0031] 1. In the multi-speed reducer of the present application, in each reduction unit, when the second-stage ring gear is connected to the first-stage planet carrier through the shifting mechanism, the second-stage ring gear and the first-stage planet carrier rotate synchronously. The power source outputs power and transmits it to the first-stage sun gear. The first-stage sun gear drives the first-stage planet gears to rotate self. The first-stage planet gears drive the first-stage ring gear to rotate. When the first-stage ring gear rotates, the power is decelerated and transmitted to the second-stage ring gear through the transmission mechanism. The second-stage ring gear drives the first-stage planet carrier to rotate, and the power is output to the half shaft through the first-stage planet carrier. The power is output after being decelerated by two levels of the first-stage planetary reduction mechanism and the transmission mechanism. Moreover, the rotation directions of the first-stage ring gear and the second-stage ring gear are opposite, so that the rotation speed of the first-stage planet carrier is reduced, realizing a gear with low speed and high torque, that is, the low-speed gear. When the second-stage ring gear is connected to the axle housing through the shifting mechanism, the rotation of the second-stage ring gear is restricted. At the same time, the rotation of the first-stage ring gear is restricted through the transmission mechanism. The power source outputs power and is output through the first-stage sun gear. Under the drive of the first-stage sun gear and the limit of the first-stage ring gear, the first-stage planet gears rotate self and revolve around the first-stage sun gear at the same time, driving the first-stage planet carrier to rotate, and the power is output to the half shaft through the first-stage planet carrier. The power is output after being decelerated by one level of the first-stage planetary reduction mechanism, realizing a gear with high speed and low torque, that is, the high-speed gear. That is, each reduction unit can achieve two-speed power output. When the power source outputs power and is input into the corresponding reduction unit through the corresponding first-stage sun gear, the first-stage planet carrier of this reduction unit outputs power to the first-stage sun gear of another reduction unit, and the first-stage planet carrier of the other reduction unit outputs power to the half shaft or the differential. Since each reduction unit can achieve two-speed power output, the gear combinations of the two reduction units can achieve four-speed power output. Therefore, the multi-speed reducer of the present application can decelerate and output the power output by the power source at multiple different reduction ratios, that is, achieve the power output of multiple gears, so as to meet the multi-gear requirements of the vehicle when driving on complex road conditions.

[0032] 2. The electric drive device of the present application can drive a half shaft to rotate alone, that is, each wheel is separately equipped with an electric drive device, or a differential is provided. After the power output by the motor is decelerated and output through the multi-speed reducer, it is transmitted to the left and right half shafts through the differential, that is, the left and right wheels are driven to rotate by one motor and the multi-speed reducer, which can meet the requirements of the electric drive system of vehicles with different drive modes.

[0033] 3. The electric drive axle assembly of the present application drives the left and right half shafts to rotate through the electric drive device, that is, the left and right wheels are driven to rotate by one electric drive device, reducing the weight and cost of the electric drive system, with high integration, small volume of the electric drive axle assembly, and reducing the space occupied by the electric drive axle assembly in the vehicle body. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of the multi-speed reducer provided by the embodiment of the present invention;

[0035] Figure 2Structural schematic diagram of the electric drive device provided by the embodiment of the present utility model;

[0036] Figure 3 Structural schematic diagram of the electric drive axle assembly provided by the embodiment of the present utility model.

[0037] Explanation of reference numerals:

[0038] 1. Reduction unit; 11. First-stage planetary reduction mechanism; 111. First-stage sun gear; 112. First-stage planetary gear; 113. First-stage planetary carrier; 114. First-stage ring gear; 12. Second-stage ring gear; 13. Transmission mechanism; 131. Second-stage sun gear; 132. Second-stage planetary gear; 133. Second-stage planetary carrier; 14. Shifting mechanism; 141. First fixed engagement sleeve; 142. Second fixed engagement sleeve; 143. Sliding engagement sleeve; 2. Axle housing; 3. Motor; 4. Differential; 5. Half shaft. Detailed implementation manners

[0039] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present application is more thorough and comprehensive.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0041] It can be understood that spatial relationship terms such as "under", "below", "lower", "beneath", "above", "upper", etc. can be used herein to describe the relationship between an element or feature shown in the figure and other elements or features. It should be understood that in addition to the orientation shown in the figure, spatial relationship terms also include different orientations of the device during use and operation. For example, if the device in the drawing is flipped, an element or feature described as "under other elements" or "beneath it" or "under it" will be oriented "above" other elements or features. Therefore, the exemplary terms "under" and "below" can include both the upper and lower orientations. In addition, the device can also include other orientations (such as rotating 90 degrees or other orientations), and the spatial description terms used herein are accordingly interpreted.

[0042] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In the following embodiments, "connection", if there is a transmission of electrical signals or data between the connected circuits, modules, units, etc., should be understood as "electrical connection", "communication connection", etc.

[0043] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprises / include" or "has" etc. specify the presence of the stated features, wholes, steps, operations, components, parts or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0044] Referring to Figure 1 As shown, an embodiment of the present application provides a multi-speed reducer, including two reduction units 1, and the reduction unit 1 includes a first-stage planetary reduction mechanism 11, a second-stage ring gear 12 and a transmission mechanism 13.

[0045] Referring to Figure 1 As shown, wherein, the first-stage planetary reduction mechanism 11 is used to be connected to the axle housing 2, and includes a first-stage sun gear 111, first-stage planet gears 112, a first-stage planet carrier 113 and a first-stage ring gear 114. The first-stage ring gear 114 coaxially surrounds the first-stage sun gear 111 and can rotate relative to the axle housing 2 about its own axis. The first-stage planet carrier 113 can rotate relative to the axle housing 2 about the axis of the first-stage sun gear 111. The first-stage planet gears 112 are located between the first-stage sun gear 111 and the first-stage ring gear 114 and are connected to the first-stage planet carrier 113. The first-stage planet gears 112 mesh with the first-stage sun gear 111 and the first-stage ring gear 114, and the first-stage planet gears 112 can rotate about their own axes and rotate with the first-stage planet carrier 113.

[0046] Referring to Figure 1 As shown, the second-stage ring gear 12 is used to be connected to the axle housing 2. The second-stage ring gear 12 coaxially surrounds the first-stage ring gear 114 and can rotate relative to the axle housing 2 about its own axis. The second-stage ring gear 12 can be selectively connected to the first-stage planet carrier 113 or the axle housing 2 through a shifting mechanism to restrict the relative rotation between the second-stage ring gear 12 and the first-stage planet carrier 113 or the axle housing 2;

[0047] Referring to Figure 1 As shown, the transmission mechanism 13 connects the first-stage ring gear 114 and the second-stage ring gear 12. When the first-stage ring gear 114 rotates, the power is decelerated and transmitted to the second-stage ring gear 12 through the transmission mechanism 13, and the rotation directions of the first-stage ring gear 114 and the second-stage ring gear 12 are opposite. When the second-stage ring gear 12 is fixedly connected to the axle housing 2 through the shifting mechanism, the second-stage ring gear 12 restricts the rotation of the first-stage ring gear 114 through the transmission mechanism 13.

[0048] Referring to Figure 1 As shown, when the second ring gear 12 is connected to the first planetary carrier 113 through a shifting mechanism, the second ring gear 12 and the first planetary carrier 113 rotate synchronously. The power source outputs power to the first sun gear 111. The first sun gear 111 drives the first planetary gear 112 to rotate self - rotatably. The first planetary gear 112 drives the first ring gear 114 to rotate. When the first ring gear 114 rotates, the power is transmitted to the second ring gear 12 through the transmission mechanism 13 after deceleration. The second ring gear 12 drives the first planetary carrier 113 to rotate, and the power is output to the half - shaft 5 through the first planetary carrier 113. The power is output after two - stage deceleration by the first planetary reduction mechanism 11 and the transmission mechanism 13. Moreover, the rotation directions of the first ring gear 114 and the second ring gear 12 are opposite, which reduces the rotation speed of the first planetary carrier 113, realizing a gear position with low speed and high torque, that is, the low - speed gear position.

[0049] Referring to Figure 1 As shown, when the second ring gear 12 is connected to the axle housing 2 through a shifting mechanism, the second ring gear 12 is restricted from rotating. At the same time, the rotation of the first ring gear 114 is restricted through the transmission mechanism 13. The power source outputs power and outputs it through the first sun gear 111. The first planetary gear 112 rotates self - rotatably and revolves around the first sun gear 111 under the drive of the first sun gear 111 and the limit of the first ring gear 114, driving the first planetary carrier 113 to rotate, and the power is output to the half - shaft 5 through the first planetary carrier 113. The power is output after one - stage deceleration by the first planetary reduction mechanism 11, realizing a gear position with high speed and low torque, that is, the high - speed gear position. Therefore, each reduction unit 1 has two gear positions.

[0050] Referring to Figure 1 As shown, to achieve the power output of multiple gear positions, the two first sun gears 111 in the two reduction units 1 are coaxial. The first sun gear 111 of one reduction unit 1 is used to connect to the power source. The first planetary carrier 113 of this reduction unit 1 is fixed to the first sun gear 111 of the other reduction unit 1, and the first planetary carrier 113 of the other reduction unit 1 is used to output power. When the power source outputs power and inputs it to the corresponding reduction unit 1 through the corresponding first sun gear 111, the first planetary carrier 113 of this reduction unit 1 outputs power to the first sun gear 111 of the other reduction unit 1, and the first planetary carrier 113 of the other reduction unit 1 outputs power to the half - shaft 5 or the differential 4. Since each reduction unit 1 can achieve two - stage power output, the gear - position combination of the two reduction units 1 can achieve four - stage power output. Therefore, the multi - speed reducer of the present application can reduce the power output by the power source with multiple different reduction ratios, that is, achieve the power output of multiple gear positions, so as to meet the multi - gear requirements of the vehicle when driving on complex road conditions.

[0051] Referring to Figure 1As shown in the figure, specifically, to achieve the purpose of the transmission mechanism 13 reducing the output power of the first-stage ring gear 114 and outputting it to the second-stage ring gear 12, the transmission mechanism 13 includes a second-stage sun gear 131, second-stage planet gears 132, and a second-stage planet carrier 133. The second-stage sun gear 131 is disposed between the second-stage ring gear 12 and the first-stage ring gear 114 and is coaxially and fixedly connected to the first-stage ring gear 114; the second-stage planet gears 132 are disposed between the second-stage sun gear 131 and the second-stage ring gear 12 and mesh with the second-stage sun gear 131 and the second-stage ring gear 12; the second-stage planet carrier 133 is fixed to the axle housing 2, and the second-stage planet gears 132 are connected to the second-stage planet carrier 133 and can rotate about their own axes. In this embodiment, the two second-stage planet carriers 133 are connected to each other and fixed to the axle housing 2.

[0052] Referring to Figure 1 As shown in the figure, when the first-stage ring gear 114 rotates, the power is output to the second-stage sun gear 131. The rotation of the second-stage sun gear 131 drives the second-stage planet gears 132 to rotate and drives the second-stage ring gear 12 to rotate, thereby achieving the purpose of reducing the output power of the first-stage ring gear 114 and outputting it to the second-stage ring gear 12.

[0053] In this embodiment, the second-stage sun gear 131 is coaxially surrounded outside the first-stage ring gear 114 and fixed to the first-stage ring gear 114.

[0054] Referring to Figure 1 As shown in the figure, further, in each reduction unit 1, the second-stage ring gear 12 can be selectively connected to the first-stage planet carrier 113 or the second-stage planet carrier 133 through a shifting mechanism to restrict the relative rotation between the second-stage ring gear 12 and the first-stage planet carrier 113 or the second-stage planet carrier 133. When the second-stage ring gear 12 is connected to the second-stage planet carrier 133, the relative rotation between the second-stage ring gear 12 and the second-stage planet carrier 133 is restricted, achieving the purpose of the shifting mechanism 14 connecting the second-stage ring gear 12 and the axle housing 2.

[0055] Referring to Figure 1 As shown in the figure, the shifting mechanism includes a first fixed engaging sleeve 141, a second fixed engaging sleeve 142, and a sliding engaging sleeve 143. The first fixed engaging sleeve 141 is coaxial with the first-stage sun gear 111 and fixed to the first-stage planet carrier 113. The second fixed engaging sleeve 142 is coaxial with the first-stage sun gear 111 and fixed to the second-stage planet carrier 133. The sliding engaging sleeve 143 is coaxial with the second-stage ring gear 12 and is connected to the second-stage ring gear 12 through a spline. The sliding engaging sleeve 143 can move axially relative to the axle housing 2, and the sliding engaging sleeve 143 can move to engage with the first fixed engaging sleeve 141 or the second fixed engaging sleeve 142.

[0056] Referring to Figure 1As shown, specifically, the first fixed engaging sleeve 141 and the second fixed engaging sleeve 142 are spaced apart in the axial direction of the half shaft 5. The sliding engaging sleeve 143 is movable in the axial direction of the half shaft 5 and can be moved to engage with the first fixed engaging sleeve 141 or the second fixed engaging sleeve 142 to achieve the shifting function. And to meet the neutral gear requirement of the vehicle, the sliding engaging sleeve 143 is configured to be movable to disengage from the first fixed engaging sleeve 141 and the second fixed engaging sleeve 142. At this time, the power output by the motor 3 cannot be transmitted to the first-stage planet gear 112 after being transmitted to the second-stage gear ring 12, and the reduction unit 1 has no power output, which is the neutral gear position.

[0057] Among the two reduction units 1, each reduction unit 1 has three gears: a high-speed gear, a low-speed gear, and a neutral gear. The combination of each other can form four gears except the neutral gear. In actual design, one of the two gears with a small difference can be retained, that is, three gears except the neutral gear are retained.

[0058] Referring to Figure 2 As shown, the embodiment of the present application further provides an electric drive device, including the multi-speed reducer and the motor 3 as described above. The output shaft of the motor 3 is coaxially fixed with the first-stage sun gear 111 for connecting the power source.

[0059] In this embodiment, the electric drive device further includes a differential 4. The first-stage planet carrier 113 for outputting power is connected to the input end of the differential 4. The output end of the differential 4 is used to connect the left and right half shafts 5, so as to transmit the power output by the first-stage planet carrier 113 to the left and right half shafts 5 through the differential 4. The left and right two half shafts 5 are driven by one electric drive device.

[0060] In this embodiment, the differential 4 includes a differential 4 housing and a differential gear pair for connecting the left and right half shafts 5. The differential 4 housing is fixed to the first-stage planet carrier 113 for outputting power and can rotate relative to the axle housing 2 about the axis of the first-stage sun gear 111. The differential gear pair is disposed inside the differential 4 housing and includes two driving bevel gears and two driven bevel gears. Both of the two driven bevel gears are coaxial with the first-stage sun gear 111 and are respectively used for being coaxially fixed to the left and right half shafts 5. The axes of the driving bevel gears are perpendicular to the axis of the first-stage sun gear 111 and are rotatably connected to the differential 4 housing. The driving bevel gears are simultaneously engaged with the two driven bevel gears. Correspondingly, the motor 3 is a hollow shaft motor 3, and the first-stage sun gear 111 is arranged in a hollow structure for the half shaft 5 to pass through. During installation, one half shaft 5 passes through the motor 3 and the two first-stage sun gears 111 and is coaxially fixed to a driven bevel gear, and the other half shaft 5 is coaxially fixed to the other driven bevel gear. In this way, when the first-stage planet carrier 113 for outputting power rotates, the differential 4 housing rotates, and the power is transmitted to the left and right half shafts 5 through the differential gear pair to achieve the differential function. Under this setting, the electric drive device can be arranged around the half shaft 5, thereby reducing the occupation of the body space in the radial direction of the half shaft 5 by the electric drive device, having a high integration degree, a small volume, and reducing the occupation of the body space.

[0061] Alternatively, in some other embodiments, the electric drive device may not include the differential 4, and the first-stage planet carrier 113 for outputting power can be directly connected to the half shaft 5, so that each half shaft 5 is driven by an electric drive device.

[0062] Referring to Figure 3 As shown, this embodiment further provides an electric drive axle assembly, which includes an axle housing 2, the electric drive device as described above, and two half shafts 5. Among them, the two half shafts 5 are coaxially arranged, the half shafts 5 are rotatably connected to the axle housing 2, and the two half shafts 5 are respectively connected to the two driven bevel gears of the differential 4.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-speed reducer, characterized in that, It includes two reduction units (1), and the reduction unit (1) includes: A first-stage planetary reduction mechanism (11) for connecting to the axle housing (2), including a first-stage sun gear (111), first-stage planet gears (112), a first-stage planet carrier (113), and a first-stage ring gear (114). The first-stage ring gear (114) coaxially surrounds the first-stage sun gear (111) and can rotate relative to the axle housing (2) about its own axis. The first-stage planet carrier (113) can rotate relative to the axle housing (2) about the axis of the first-stage sun gear (111). The first-stage planet gears (112) are located between the first-stage sun gear (111) and the first-stage ring gear (114) and are connected to the first-stage planet carrier (113). The first-stage planet gears (112) mesh with the first-stage sun gear (111) and the first-stage ring gear (114), and the first-stage planet gears (112) can rotate about their own axes and rotate with the first-stage planet carrier (113); A second-stage ring gear (12) for connecting to the axle housing (2). The second-stage ring gear (12) coaxially surrounds the first-stage ring gear (114) and can rotate relative to the axle housing (2) about its own axis. The second-stage ring gear (12) can be selectively connected to the first-stage planet carrier (113) or the axle housing (2) through a shifting mechanism to limit the relative rotation between the second-stage ring gear (12) and the first-stage planet carrier (113) or the axle housing (2); A transmission mechanism (13) connecting the first-stage ring gear (114) and the second-stage ring gear (12). When the first-stage ring gear (114) rotates, power is decelerated and transmitted to the second-stage ring gear (12) through the transmission mechanism (13), and the rotation directions of the first-stage ring gear (114) and the second-stage ring gear (12) are opposite. When the second-stage ring gear (12) is fixedly connected to the axle housing (2) through the shifting mechanism, the second-stage ring gear (12) limits the rotation of the first-stage ring gear (114) through the transmission mechanism (13); Wherein, the two first-stage sun gears (111) in the two reduction units (1) are coaxial. The first-stage sun gear (111) of one of the reduction units (1) is used to connect to a power source, and the first-stage planet carrier (113) of this reduction unit (1) is fixed to the first-stage sun gear (111) of the other reduction unit (1), and the first-stage planet carrier (113) of the other reduction unit (1) is used to output power.

2. The multi-speed reducer according to claim 1, wherein, The transmission mechanism (13) includes: A second-stage sun gear (131) disposed between the second-stage ring gear (12) and the first-stage ring gear (114) and fixedly connected to the first-stage ring gear (114) coaxially; Second-stage planet gears (132) disposed between the second-stage sun gear (131) and the second-stage ring gear (12) and meshing with the second-stage sun gear (131) and the second-stage ring gear (12); A second-stage planet carrier (133) for fixing to the axle housing (2). The second-stage planet gears (132) are connected to the second-stage planet carrier (133) and can rotate about their own axes.

3. The multi-speed reducer according to claim 2, characterized in that: In each of the deceleration units (1), the secondary gear ring (12) can be selectively connected to the primary planet carrier (113) or the secondary planet carrier (133) through a shifting mechanism to limit the relative rotation between the secondary gear ring (12) and the primary planet carrier (113) or the secondary planet carrier (133).

4. The multi-speed reducer according to claim 1, characterized in that, The shifting mechanism includes: A first fixed engaging sleeve (141), which is coaxial with the primary sun gear (111) and fixed to the primary planet carrier (113); A second fixed engaging sleeve (142), which is coaxial with the primary sun gear (111) and fixed to the axle housing (2); A sliding engaging sleeve (143), which is coaxial with the secondary gear ring (12) and connected to the secondary gear ring (12) through splines. The sliding engaging sleeve (143) can move axially relative to the axle housing (2), and the sliding engaging sleeve (143) can move to engage with the first fixed engaging sleeve (141) or the second fixed engaging sleeve (142).

5. The multi-stage speed reducer according to claim 4, wherein: The sliding engaging sleeve (143) can move to disengage from the first fixed engaging sleeve (141) and the second fixed engaging sleeve (142).

6. An electric drive device, characterized in that, Includes: A multi-speed reducer according to any one of claims 1-5; A motor (3), the output shaft of which is coaxially fixed to the primary sun gear (111) for connecting a power source.

7. The electric drive device according to claim 6, characterized in that: It further includes a differential (4). The primary planet carrier (113) for outputting power is connected to the input end of the differential (4), and the output end of the differential (4) is used to connect to the left and right half shafts (5) so as to transmit the power output by the primary planet carrier (113) to the left and right half shafts (5) through the differential (4).

8. An electric drive bridge assembly, characterized in that, Includes: An axle housing (2); The electric drive device according to claim 7, provided in the axle housing (2); Two half shafts (5) arranged coaxially, the half shafts (5) are rotatably connected to the axle housing (2), and the two half shafts (5) are respectively connected to the two output ends of the differential (4).

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