A multi-speed electric drive transmission system

Abstract

The present invention provides a multi-speed electric drive transmission system, which includes a shaft I, a shaft II, a shaft III (8), and a shaft IV (26) that are arranged in parallel with each other. The left half shaft (25) and the right half shaft (1) are concentrically arranged with the shaft III. The motor and the gearbox are integrally designed, with a compact space. The shaft III and the differential are concentrically designed, and the power transmission path returns from the shaft IV to the shaft III, reducing the offset. The shaft III and the left half shaft adopt a sleeve shaft design, and the left half shaft passes through the shaft III for output. One shift actuator controls 3 clutches. Each gear is shifted by rotating the shift drum in sequence, realizing mechanical interlock between gears, improving safety and reducing the control difficulty.

Description

Technical Field

[0001] The present invention relates to the field of transmissions for new energy commercial vehicles, and particularly to a multi-speed electric drive axle transmission system. Background Art

[0002] With the development of new energy electric drive technology, in order to save space, shorten the transmission path, and improve transmission efficiency, the transmission system has gradually developed from a central drive mode to an axle drive mode.

[0003] Currently, for the electric drive axles of commercial vehicles used in the market, one type is a single motor combined with a traditional AMT gearbox, which uses a low-speed high-torque motor. Although the structure is simple, the weight is large, resulting in a large unsprung mass, which in turn leads to increased vibration and reliability problems. At the same time, for many applications of commercial vehicles, a larger motor is required to provide sufficient power; in addition, the offset of the input and output structure makes it difficult to arrange on the vehicle, which is also a major defect. Another type uses a dual-motor structure (such as CN108001185A, CN108725178A). Although the weight problem is solved, due to an additional set of motors and electronic control equipment, the cost is high and it is not recognized by the market. Summary of the Invention

[0004] In order to solve the defects and deficiencies in the prior art, the present invention provides a multi-speed electric drive axle transmission system.

[0005] The technical solution provided by the present invention is as follows: A multi-speed electric drive transmission system, the transmission system comprising:

[0006] Motor EM (6);

[0007] The output shaft of the motor EM (6) outputs power to the shaft III (8) through a two-stage reduction mechanism;

[0008] Shaft III (8), the shaft III (8) is a hollow shaft, and a first-gear driving gear (15), a third-gear driving gear (17), a second-gear driving gear (19), and a fourth-gear driving gear (22) are sleeved on the shaft III (8) from left to right in sequence;

[0009] Shaft IV (26), on which a first-gear driven gear (16), a third-gear driven gear (18), a second-gear driven gear (20), a fourth-gear driven gear (21), and an output driving gear (23) are fixedly arranged from left to right in sequence. Among them, the first-gear driven gear (16) meshes with the first-gear driving gear (15) correspondingly, the third-gear driven gear (18) meshes with the third-gear driving gear (17) correspondingly, the second-gear driven gear (20) meshes with the second-gear driving gear (19) correspondingly, and the fourth-gear driven gear (21) meshes with the fourth-gear driving gear (22) correspondingly;

[0010] Differential, the differential includes a differential housing (3), and an output driven gear (24) corresponding to and meshing with an output driving gear (23) is provided on the differential housing (3);

[0011] Differential lock DL (4), the differential lock DL is arranged on the left half shaft (25) and is located between the fourth gear driving gear (22) and the output driven gear (24);

[0012] Clutch A (7), the clutch A is sleeved on the shaft Ⅲ (8) and is located between the first gear driving gear (15) and the third gear driving gear (17);

[0013] Clutch B (5), the clutch B is sleeved on the shaft Ⅲ (8) and is located between the second gear driving gear (19) and the fourth gear driving gear (22);

[0014] Shift drum and shift execution mechanism (27), the shift drum and shift execution mechanism (27) are respectively connected to the clutch A (7), the clutch B (5), and the differential lock DL (4).

[0015] Furthermore, the transmission system further includes:

[0016] Shaft Ⅰ, the output shaft of the motor EM (6) is connected to the input driving gear (13) via the shaft Ⅰ;

[0017] Shaft Ⅱ, a second-stage driving gear (11) and an input driven gear (14) are fixedly arranged on the shaft Ⅱ, wherein the input driven gear (14) corresponds to and meshes with the input driving gear (13);

[0018] On the left side of the shaft Ⅲ (8), a second-stage driven gear (9) corresponding to and meshing with the second-stage driving gear (11) is fixedly arranged.

[0019] Furthermore, the shaft Ⅰ, the shaft Ⅱ, the shaft Ⅲ (8), and the shaft Ⅳ (26) are arranged in parallel, and the left half shaft (25) and the right half shaft (1) are concentric with the shaft Ⅲ (8).

[0020] Furthermore, the transmission system further includes an oil pump shaft, an oil pump gear (12) corresponding to and meshing with the second-stage driving gear (11) is fixedly arranged on the oil pump shaft, and an oil pump (10) is also connected to the oil pump shaft.

[0021] Furthermore, the transmission system can achieve the following gears:

[0022] Neutral gear N: Both the clutch A and the clutch B are in the middle position, and the differential lock DL is opened. At this time, it is in the neutral gear mode;

[0023] 1.1) First mode of first gear: Clutch A is combined on the left, clutch B is in the middle position, differential lock DL is closed, and the left and right half shafts are locked;

[0024] 1.2) Second mode of first gear: Clutch A is combined on the left, clutch B is in the middle position, and differential lock DL is open;

[0025] 2) Second gear: Clutch B is combined on the left, and clutch A is in the middle position;

[0026] 3) Third gear: Clutch A is combined on the right, and clutch B is in the middle position;

[0027] 4) Fourth gear: Clutch B is combined on the right, and clutch A is in the middle position.

[0028] Furthermore, the transmission system includes a shift motor, which is connected to a shift drum and a shift actuator (27) and drives the shift drum to rotate through the shift actuator. There are 3 sections of grooves on the surface of the shift drum to respectively control clutch A, clutch B, and differential lock DL. The grooves drive the fork guide pins to achieve gear shifting. The shift drum has a gear interlock function, and only one of clutch A and clutch B is in gear at the same time;

[0029] The corresponding gear shifting processes of the transmission system are as follows:

[0030] Under normal circumstances, clutch A is combined on the left, and the vehicle starts by shifting from N gear to first gear;

[0031] When shifting from first gear to second gear, motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position; then, after motor EM adjusts the speed until the second gear driving gear is synchronized with the clutch B engagement sleeve, the shift drum continues to rotate to control clutch B to be combined on the left. After the gear is combined, motor EM restores torque to complete the gear shift from first gear to second gear;

[0032] When shifting from second gear to third gear, motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch B to return to the middle position; then, after motor EM adjusts the speed until the third gear driving gear is synchronized with the clutch A engagement sleeve, the shift drum continues to rotate to control clutch A to be combined on the right. After the gear is combined, motor EM restores torque to complete the gear shift from second gear to third gear;

[0033] When shifting from third gear to fourth gear, motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position; then, after motor EM adjusts the speed until the fourth gear driving gear is synchronized with the clutch B engagement sleeve, the shift drum continues to rotate to control clutch B to be combined on the right. After the gear is combined, motor EM restores torque to complete the gear shift from third gear to fourth gear;

[0034] The downshift mode is carried out in the reverse of the above process;

[0035] When a starting fault occurs with one side tire slipping, the shift motor drives and controls the shift drum to move into the first gear first mode to lock the differential and thus increase the driving force of the vehicle.

[0036] Furthermore, a multi-gear electric drive transmission system is also proposed. The transmission system includes:

[0037] Motor EM (6);

[0038] The output shaft of the motor EM (6) outputs power to the secondary driven gear (9) of the III shaft (8) through a two-stage reduction mechanism;

[0039] III shaft (8), the III shaft is a hollow shaft, and a secondary driven gear (9), a second-gear driving gear (19), and a first-gear driving gear (15) are sequentially sleeved on the III shaft from left to right. The secondary driven gear (9) meshes with the secondary driving gear (11);

[0040] IV shaft (26), on the IV shaft, a third-gear driven gear (18), a second-gear driven gear (20), a first-gear driven gear (16), and an output driving gear (23) are sequentially fixedly arranged from left to right. Among them, the third-gear driven gear (18) meshes with the secondary driven gear (9), the second-gear driven gear (20) meshes with the second-gear driving gear (19), and the first-gear driven gear (16) meshes with the first-gear driving gear (15);

[0041] Differential, the differential includes a differential housing (3), and an output driven gear (24) meshing with the output driving gear (23) is arranged on the differential housing (3);

[0042] Clutch A (7), the Clutch A is arranged on the IV shaft (26) and is located between the second-gear driven gear (20) and the first-gear driven gear (16); the Clutch A (7) includes a third-gear hub (71) and a third-gear engaging sleeve (72);

[0043] Clutch B (5), the Clutch B is arranged on the IV shaft (26) and is located between the third-gear driven gear (18) and the second-gear driven gear (20); the Clutch B (5) includes a first-and-second-gear hub (51) and a first-and-second-gear engaging sleeve (52);

[0044] Shift drum and shift execution mechanism, the shift drum and the shift execution mechanism are respectively connected to the Clutch A (7) and the Clutch B (5).

[0045] Furthermore, the transmission system further includes:

[0046] I shaft, the output shaft of the motor EM (6) is connected to the input driving gear (13) through the I shaft;

[0047] The second shaft, on which a secondary driving gear (11) and an input driven gear (14) are fixedly arranged. Among them, the input driven gear (14) meshes with the input driving gear (13) correspondingly.

[0048] On the left side of the third shaft (8), a secondary driven gear (9) meshing with the secondary driving gear (11) correspondingly is fixedly arranged.

[0049] Further, the first shaft, the second shaft, the third shaft (8), and the fourth shaft (26) are arranged parallel to each other, and the left half shaft (25) and the right half shaft (1) are arranged concentrically with the third shaft.

[0050] Further, the transmission system can achieve the following gears:

[0051] 1) First gear: Clutch A is combined on the right, and clutch B is not combined.

[0052] 2) Second gear: Clutch A is combined on the left, and clutch B is not combined.

[0053] 3) Third gear: Clutch A is in the middle position, and clutch B is combined on the left.

[0054] 4) Neutral gear: Clutch A is in the middle position, and clutch B is not combined.

[0055] Further, the transmission system includes a shift motor, which is connected to a shift drum and a shift execution mechanism and drives the shift drum to rotate through the shift execution mechanism. Two sections of grooves are arranged on the surface of the shift drum to respectively control clutch A and clutch B. The grooves drive the shift fork guide pins to achieve gear shifting. The shift drum has a gear interlock function, and only one of clutch A and clutch B is in gear at the same time.

[0056] The corresponding gear shifting processes of the transmission system are as follows:

[0057] When the vehicle starts, clutch A is combined on the right, and it is shifted from neutral gear to first gear to achieve vehicle start.

[0058] When shifting from first gear to second gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position. Then, after the motor EM adjusts the speed to make the second gear driving gear synchronize with the clutch A engagement sleeve, the shift drum continues to rotate to control clutch A to be combined on the left. After the gear is combined, the torque of the motor EM is restored to complete the gear shift from first gear to second gear.

[0059] When shifting from second gear to third gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position. Then, after the motor EM adjusts the speed to make the third gear driving gear synchronize with the clutch B engagement sleeve, the shift drum continues to rotate to control clutch B to be combined. After the gear is combined, the torque of the motor EM is restored to complete the gear shift from second gear to third gear.

[0060] The downshift mode proceeds in the reverse direction of the above process.

[0061] Furthermore, a multi-speed electric drive transmission system is also proposed. The transmission system includes:

[0062] An electric motor EM (6);

[0063] The output shaft of the electric motor EM (6) outputs power to the secondary driven gear (9) of the third shaft (8) through a two-stage reduction mechanism.

[0064] The third shaft (8) is a hollow shaft. A secondary driven gear (9), a second-gear driving gear (19), and a first-gear driving gear (15) are sleeved on the third shaft from left to right in sequence. The secondary driven gear (9) meshes with the secondary driving gear (11) correspondingly.

[0065] The fourth shaft (26). A third-gear driven gear (18), a second-gear driven gear (20), a first-gear driven gear (16), and an output driving gear (23) are fixedly arranged on the fourth shaft from left to right in sequence. Among them, the third-gear driven gear (18) meshes with the secondary driven gear (9) correspondingly, the second-gear driven gear (20) meshes with the second-gear driving gear (19) correspondingly, and the first-gear driven gear (16) meshes with the first-gear driving gear (15) correspondingly.

[0066] A differential. The differential includes a differential housing (3). An output driven gear (24) that meshes with the output driving gear (23) correspondingly is arranged on the differential housing (3).

[0067] Clutch A (7). Clutch A is sleeved on the third shaft (8) and is located between the first-gear driving gear (15) and the second-gear driving gear (19). Clutch A (7) includes a third-gear hub (71) and a third-gear engaging sleeve (72).

[0068] Clutch B (5). Clutch B is arranged on the fourth shaft (26) and is located between the third-gear driven gear (18) and the second-gear driven gear (20). Clutch B (5) includes a first-and-second-gear hub (51) and a first-and-second-gear engaging sleeve (52).

[0069] A shift drum and a shift execution mechanism. The shift drum and the shift execution mechanism are respectively connected to Clutch A (7) and Clutch B (5).

[0070] Furthermore, the transmission system further includes:

[0071] The first shaft. The output shaft of the electric motor EM (6) is connected to the input driving gear (13) through the first shaft.

[0072] The second shaft, on which a secondary driving gear (11) and an input driven gear (14) are fixedly arranged. Among them, the input driven gear (14) meshes with the input driving gear (13) correspondingly.

[0073] On the left side of the third shaft (8), a secondary driven gear (9) meshing with the secondary driving gear (11) correspondingly is fixedly arranged.

[0074] Furthermore, the first shaft, the second shaft, the third shaft (8), and the fourth shaft (26) are arranged parallel to each other, and the left half shaft (25) and the right half shaft (1) are arranged concentrically with the third shaft.

[0075] Furthermore, the transmission system can achieve the following gears:

[0076] 1) First gear: Clutch A is combined on the right, and clutch B is not combined.

[0077] 2) Second gear: Clutch A is combined on the left, and clutch B is not combined.

[0078] 3) Third gear: Clutch A is in the middle position, and clutch B is combined on the left.

[0079] 4) Neutral gear: Clutch A is in the middle position, and clutch B is not combined.

[0080] Furthermore, the transmission system includes a shift motor, which is connected to a shift drum and a shift execution mechanism and drives the shift drum to rotate through the shift execution mechanism. Two sections of grooves are arranged on the surface of the shift drum to respectively control clutch A and clutch B. The grooves drive the shift fork guide pins to achieve gear shifting. The shift drum has a gear interlock function, and only one of clutch A and clutch B is in gear at the same time.

[0081] The corresponding gear shifting process of the transmission system is as follows:

[0082] When the vehicle starts, clutch A is combined on the right, and it is shifted from neutral gear to first gear to achieve vehicle start.

[0083] When shifting from first gear to second gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position; then after the motor EM adjusts the speed to make the second gear driving gear synchronize with the clutch A engagement sleeve, the shift drum continues to rotate to control clutch A to be combined on the left. After the gear is combined, the torque of the motor EM is restored to complete the gear shift from first gear to second gear.

[0084] When shifting from second gear to third gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position; then after the motor EM adjusts the speed to make the third gear driving gear synchronize with the clutch B engagement sleeve, the shift drum continues to rotate to control clutch B to be combined on the left. After the gear is combined, the torque of the motor EM is restored to complete the gear shift from second gear to third gear.

[0085] The downshift mode proceeds in the reverse direction of the above process.

[0086] Furthermore, the present invention also provides a four-wheel drive vehicle employing the above multi-speed electric drive transmission system, characterized in that: the left half shaft of the multi-speed electric drive transmission system is correspondingly meshed with the front axle differential input gear fixedly connected to the differential case of the front drive axle of the four-wheel drive vehicle, and the right half shaft of the multi-speed electric drive transmission system is correspondingly meshed with the rear axle differential input gear fixedly connected to the differential case of the rear drive axle of the four-wheel drive vehicle.

[0087] The beneficial effects achieved by the present invention compared with the prior art are as follows:

[0088] 1) The present invention provides a multi-speed electric drive axle transmission system with an integrated design of the motor and the gearbox, resulting in a compact space; the concentric design of the third shaft and the differential reduces the offset as the power transmission path returns from the fourth shaft to the third shaft; the third shaft and the left half shaft adopt a sleeve shaft design, and the left half shaft passes through the third shaft for output; one shift actuator controls three clutches; each gear is shifted sequentially by rotating the shift drum, achieving mechanical interlock between gears, improving safety and reducing the control difficulty.

[0089] 2) The present invention provides a multi-speed electric drive axle transmission system that eliminates components such as clutches, drive shafts, and universal joints, optimizing the transmission efficiency; the transmission gear pairs and the main reduction gear pairs adopt cylindrical gear transmissions, resulting in a high system efficiency.

[0090] 3) The present invention provides a multi-speed electric drive axle transmission system. With the clutch A located on the third shaft, compared with the scheme where the clutch A is located on the fourth shaft, the synchronous inertia during the shift between the first and second gears is smaller, the motor synchronization time is shorter, and the relative shift speed is faster. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 It is a schematic structural diagram of the first embodiment of the present invention.

[0092] Figure 2 It is a schematic structural diagram of the second embodiment of the present invention.

[0093] Figure 3 It is a schematic structural diagram of the third embodiment of the present invention.

[0094] Figure 4 It is a schematic diagram of the surface grooves of the shift drum under various working conditions in the first embodiment of the present invention.

[0095] Figure 5 It is a schematic structural diagram of a four-wheel drive vehicle employing the multi-speed electric drive transmission system in the first, second, or third embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0096] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0097] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0098] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0099] As Figure 1 shown is a multi-speed electric drive transmission system provided by the first embodiment of the present invention. The transmission system includes: a motor EM6;

[0100] A shaft I. The output shaft of the motor EM6 is connected to an input driving gear 13 through the shaft I;

[0101] A shaft II. A second-stage driving gear 11 and an input driven gear 14 are fixedly arranged on the shaft II. Among them, the input driven gear 14 is meshed with the input driving gear 13 correspondingly;

[0102] A shaft III 8. The shaft III is a hollow shaft. A second-stage driven gear 9 meshed with the second-stage driving gear 11 is fixedly arranged on the left side of the shaft III. A first-speed driving gear 15, a third-speed driving gear 17, a second-speed driving gear 19, and a fourth-speed driving gear 22 are sleeved on the right side of the shaft III in sequence from left to right;

[0103] The fourth shaft 26, on which a first-gear driven gear 16, a third-gear driven gear 18, a second-gear driven gear 20, a fourth-gear driven gear 21, and an output driving gear 23 are fixedly arranged in sequence from left to right. Among them, the first-gear driven gear 16 meshes with the first-gear driving gear 15 correspondingly, the third-gear driven gear 18 meshes with the third-gear driving gear 17 correspondingly, the second-gear driven gear 20 meshes with the second-gear driving gear 19 correspondingly, and the fourth-gear driven gear 21 meshes with the fourth-gear driving gear 22 correspondingly;

[0104] Differential, the differential includes a differential housing 3, on which an output driven gear 24 that meshes with the output driving gear 23 correspondingly is arranged. The left half shaft 25 of the differential is concentric with the third shaft and penetrates inside the third shaft to output power to the left wheel of the vehicle. The right half shaft 1 of the differential outputs power to the right wheel of the vehicle. The left half shaft 25 and the right half shaft 1 are respectively connected with half shaft gears inside the differential, and the half shaft gears mesh with the differential planet gears 2;

[0105] Oil pump shaft, on which an oil pump gear 12 that meshes with the second-stage driving gear 11 correspondingly is fixedly arranged, and an oil pump 10 is also connected to the oil pump shaft;

[0106] Differential lock DL4, the differential lock DL is arranged on the left half shaft 25 and is located between the fourth-gear driving gear 22 and the output driven gear 24;

[0107] Clutch A7, the clutch A is sleeved on the third shaft 8 and is located between the first-gear driving gear 15 and the third-gear driving gear 17;

[0108] Clutch B5, the clutch B is sleeved on the third shaft 8 and is located between the second-gear driving gear 19 and the fourth-gear driving gear 22;

[0109] Shift drum and shift execution mechanism 27, the shift drum and shift execution mechanism 27 are respectively connected with the clutch A7, the clutch B5, and the differential lock DL4.

[0110] Specifically, the first shaft, the second shaft, the third shaft 8, and the fourth shaft 26 are arranged parallel to each other, and the left half shaft 25 and the right half shaft 1 are concentric with the third shaft.

[0111] Specifically, the transmission system can achieve the following gears (as shown in Table 1):

[0112] Table 1 Working table of clutches and differential locks corresponding to each gear in the first embodiment of the present invention

[0113]

[0114] Note: √ represents the corresponding working positions of the corresponding clutches and differential locks in each gear.

[0115] Neutral N: Clutch A and clutch B are both in the middle position, and the differential lock DL is open. This is the neutral mode.

[0116] 1.1) First mode of first gear: Clutch A is combined on the left, clutch B is in the middle position, the differential lock DL is closed, and the left and right half shafts are locked.

[0117] 1.2) Second mode of first gear: Clutch A is combined on the left, clutch B is in the middle position, and the differential lock DL is open.

[0118] 2) Second gear: Clutch B is combined on the left, and clutch A is in the middle position.

[0119] 3) Third gear: Clutch A is combined on the right, and clutch B is in the middle position.

[0120] 4) Fourth gear: Clutch B is combined on the right, and clutch A is in the middle position.

[0121] Specifically, the transmission system includes a shift motor. The shift motor is connected to a shift drum and a shift actuator (27) and drives the shift drum to rotate through the shift actuator. Three grooves are provided on the surface of the shift drum to respectively control clutch A, clutch B, and the differential lock DL. The grooves drive the fork guide pins to achieve gear shifting. The shift drum has a gear interlock function, and only one of clutch A and clutch B is in gear at the same time.

[0122] See appendix Figure 4 , and the corresponding gear shifting processes of the transmission system are as follows:

[0123] Under normal circumstances, clutch A is combined on the left, and the first gear is engaged to start the vehicle.

[0124] When shifting from the first gear to the second gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position; then, after the motor EM adjusts the speed to synchronize the second gear driving gear with the clutch B engagement sleeve, the shift drum continues to rotate to control clutch B to be combined on the left. After the gear combination is completed, the torque of the motor EM is restored, and the gear shift from the first gear to the second gear is completed.

[0125] When shifting from the second gear to the third gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch B to return to the middle position; then, after the motor EM adjusts the speed to synchronize the third gear driving gear with the clutch A engagement sleeve, the shift drum continues to rotate to control clutch A to be combined on the right. After the gear combination is completed, the torque of the motor EM is restored, and the gear shift from the second gear to the third gear is completed.

[0126] When shifting from the third gear to the fourth gear, the motor EM reduces torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position. Then, after the motor EM adjusts the speed so that the fourth-gear driving gear is synchronized with the clutch B engaging sleeve, the shifting drum continues to rotate to control the clutch B to engage on the right. After the gear engagement is completed, the torque of the motor EM is restored, and the gear shift from the third gear to the fourth gear is completed.

[0127] The downshift mode proceeds in the reverse direction of the above process.

[0128] When a starting fault occurs with one side tire slipping, the shifting motor drives and controls the shifting drum to act and enter the first mode of the first gear to lock the differential and thus increase the driving force of the vehicle.

[0129] In this first embodiment, the motor and the gearbox are integrally designed, with a compact space; the III shaft and the differential are concentrically designed, and the power transmission path returns from the IV shaft to the III shaft, reducing the offset; the III shaft and the left half shaft adopt a bushing shaft design, and the left half shaft passes through the III shaft for output; one shifting actuator controls three clutches; each gear is shifted sequentially by rotating the shifting drum, achieving mechanical interlock of the gears, improving safety, and reducing the control difficulty.

[0130] As Figure 2 shown is a multi-speed electric drive transmission system provided by the second embodiment of the present invention. The transmission system includes: a motor EM6;

[0131] A shaft I, and the output shaft of the motor EM6 is connected to an input driving gear 13 via the shaft I;

[0132] A shaft II, on which a secondary driving gear 11 and an input driven gear 14 are fixedly arranged. Among them, the input driven gear 14 meshes with the input driving gear 13 correspondingly;

[0133] A shaft III 8, the shaft III is a hollow shaft, and a secondary driven gear 9, a second-gear driving gear 19, and a first-gear driving gear 15 are sleeved on the shaft III from left to right in sequence. The secondary driven gear 9 meshes with the secondary driving gear 11 correspondingly;

[0134] A shaft IV 26, on which a third-gear driven gear 18, a second-gear driven gear 20, a first-gear driven gear 16, and an output driving gear 23 are fixedly arranged from left to right in sequence. Among them, the third-gear driven gear 18 meshes with the secondary driven gear 9 correspondingly, the second-gear driven gear 20 meshes with the second-gear driving gear 19 correspondingly, and the first-gear driven gear 16 meshes with the first-gear driving gear 15 correspondingly;

[0135] Differential, the differential includes a differential housing 3, on which an output driven gear 24 corresponding to and meshing with the output driving gear 23 is provided. The left half shaft 25 of the differential is concentric with the III shaft and passes through the interior of the III shaft to output power to the left wheel of the vehicle. The right half shaft 1 of the differential outputs power to the right wheel of the vehicle. The left half shaft 25 and the right half shaft 1 are respectively connected with half shaft gears inside the differential, and the half shaft gears mesh with the differential planet gears;

[0136] Clutch A7, the Clutch A is arranged on the IV shaft 26 and is located between the second gear driven gear 20 and the first gear driven gear 16; the Clutch A7 includes a third gear hub 71 and a third gear engaging sleeve 72;

[0137] Clutch B5, the Clutch B is arranged on the IV shaft 26 and is located between the third gear driven gear 18 and the second gear driven gear 20; the Clutch B5 includes a first and second gear hub 51 and a first and second gear engaging sleeve 52;

[0138] Shift drum and shift execution mechanism, the shift drum and shift execution mechanism are respectively connected with the Clutch A7 and the Clutch B5;

[0139] The I shaft, II shaft, III shaft 8, and IV shaft 26 are arranged parallel to each other, and the left half shaft 25 and the right half shaft 1 are concentric with the III shaft.

[0140] Specifically, the transmission system can achieve the following gears (as shown in Table 2):

[0141] Table 2 Clutch working table for each gear in the second embodiment of the present invention

[0142]

[0143] Note: √ indicates the corresponding working position of the corresponding clutch in each gear.

[0144] 1) First gear: Clutch A is combined on the right, and Clutch B is not combined;

[0145] 2) Second gear: Clutch A is combined on the left, and Clutch B is not combined;

[0146] 3) Third gear: Clutch A is in the middle position, and Clutch B is combined on the left;

[0147] 4) N gear: Clutch A is in the middle position, and Clutch B is not combined.

[0148] Specifically, the transmission system includes a shift motor, which is connected to a shift drum and a shift actuator and drives the shift drum to rotate through the shift actuator. Two sections of grooves are provided on the surface of the shift drum to respectively control clutch A and clutch B. The grooves drive the fork guide pins to achieve gear shifting. The shift drum has a gear interlock function, and only one of clutch A and clutch B is in gear at the same time;

[0149] The corresponding gear shifting processes of the transmission system are as follows:

[0150] When the vehicle starts, clutch A is combined on the right, and it is shifted from N gear to 1 gear to realize vehicle start;

[0151] When shifting from 1 gear to 2 gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position; then after the motor EM adjusts the speed to synchronize the second gear driving gear with the engagement sleeve of clutch A, the shift drum continues to rotate, controls clutch A to be combined on the left. After the gear combination is completed, the torque of the motor EM is restored to complete the gear shift from 1 gear to 2 gear;

[0152] When shifting from 2 gear to 3 gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position; then after the motor EM adjusts the speed to synchronize the third gear driving gear with the engagement sleeve of clutch B, the shift drum continues to rotate, controls clutch B to be combined. After the gear combination is completed, the torque of the motor EM is restored to complete the gear shift from 2 gear to 3 gear;

[0153] The downshift mode is carried out in the reverse of the above process.

[0154] In this second embodiment, the motor, transmission, main reducer and differential are integrated into one, replacing the power chain of traditional vehicles, eliminating links such as clutches, drive shafts and universal joints, and optimizing the transmission efficiency; at the same time, three gears are set according to the requirements of the adapted vehicle model, and the different speed ratio combinations of the high-speed motor and the three gears meet the use requirements, and the overall cost is relatively low; the transmission gear pair and the main reduction gear pair adopt cylindrical gear transmission, and the system efficiency is high.

[0155] As Figure 3 shown is a multi-gear electric drive transmission system provided by the third embodiment of the present invention. The transmission system includes: a motor EM6;

[0156] Shaft I, the output shaft of the motor EM6 is connected to the input driving gear 13 through shaft I;

[0157] Shaft II, a second-stage driving gear 11 and an input driven gear 14 are fixedly arranged on shaft II, wherein the input driven gear 14 is correspondingly meshed with the input driving gear 13;

[0158] The third shaft 8, the third shaft is a hollow shaft, and a secondary driven gear 9, a second gear driving gear 19, and a first gear driving gear 15 are sleeved on the third shaft from left to right in sequence. The secondary driven gear 9 meshes with the secondary driving gear 11 correspondingly;

[0159] The fourth shaft 26, a third gear driven gear 18, a second gear driven gear 20, a first gear driven gear 16, and an output driving gear 23 are fixedly arranged on the fourth shaft from left to right in sequence. Among them, the third gear driven gear 18 meshes with the secondary driven gear 9 correspondingly, the second gear driven gear 20 meshes with the second gear driving gear 19 correspondingly, and the first gear driven gear 16 meshes with the first gear driving gear 15 correspondingly;

[0160] Differential, the differential includes a differential housing 3, an output driven gear 24 meshing with the output driving gear 23 correspondingly is arranged on the differential housing 3. The left half shaft 25 of the differential is concentric with the third shaft and penetrates through the inside of the third shaft to output power to the left wheel of the vehicle. The right half shaft 1 of the differential outputs power to the right wheel of the vehicle. The left half shaft 25 and the right half shaft 1 are respectively connected with half shaft gears inside the differential, and the half shaft gears mesh with the differential planet gears;

[0161] Clutch A7, the clutch A is sleeved on the third shaft 8 and is located between the first gear driving gear 15 and the second gear driving gear 19; the clutch A7 includes a third gear hub 71 and a third gear engaging sleeve 72;

[0162] Clutch B5, the clutch B is arranged on the fourth shaft 26 and is located between the third gear driven gear 18 and the second gear driven gear 20; the clutch B5 includes a first and second gear hub 51 and a first and second gear engaging sleeve 52;

[0163] Shift drum and shift execution mechanism, the shift drum and the shift execution mechanism are respectively connected with the clutch A7 and the clutch B5;

[0164] The first shaft, the second shaft, the third shaft 8, and the fourth shaft 26 are arranged in parallel with each other, and the left half shaft 25 and the right half shaft 1 are concentric with the third shaft.

[0165] Specifically, the transmission system can achieve the following gears (as shown in Table 3):

[0166] Table 3 Clutch working table for each gear in the third embodiment of the present invention

[0167]

[0168] Note: √ represents the corresponding working position of the corresponding clutch in each gear.

[0169] 1) First gear: Clutch A is combined on the right, and clutch B is not combined;

[0170] 2) Second gear: Clutch A is engaged on the left, and clutch B is not engaged.

[0171] 3) Third gear: Clutch A is in the middle position, and clutch B is engaged on the left.

[0172] 4) N gear: Clutch A is in the middle position, and clutch B is not engaged.

[0173] Specifically, the transmission system includes a shift motor, which is connected to a shift drum and a shift actuator and drives the shift drum to rotate through the shift actuator. There are 2 sections of grooves on the surface of the shift drum to respectively control clutch A and clutch B. The grooves drive the fork guide pins to achieve gear shifting. The shift drum has a gear interlock function, and only one of clutch A and clutch B is in gear at the same time.

[0174] The corresponding gear shifting processes of the transmission system are as follows:

[0175] When the vehicle starts, clutch A is engaged on the right, and it is shifted from N gear to 1st gear to achieve vehicle start.

[0176] When shifting from 1st gear to 2nd gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A back to the middle position; then after the motor EM adjusts the speed to make the second gear driving gear synchronize with the engagement sleeve of clutch A, the shift drum continues to rotate to control clutch A to be engaged on the left. After the gear engagement is completed, the torque of the motor EM is restored, and the gear shift from 1st gear to 2nd gear is completed.

[0177] When shifting from 2nd gear to 3rd gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A back to the middle position; then after the motor EM adjusts the speed to make the third gear driving gear synchronize with the engagement sleeve of clutch B, the shift drum continues to rotate to control clutch B to be engaged on the left. After the gear engagement is completed, the torque of the motor EM is restored, and the gear shift from 2nd gear to 3rd gear is completed.

[0178] The downshift mode is carried out in the reverse direction of the above process.

[0179] In this third embodiment, clutch A is located on the III shaft. Compared with the scheme where clutch A is located on the IV shaft, the synchronous inertia during the shift between 1st gear and 2nd gear is smaller, the motor synchronization time is shorter, and the relative shift speed is faster.

[0180] As Figure 5 shown, the present invention also provides a four-wheel drive vehicle adopting the above multi-gear electric drive transmission system. The left half shaft 25 of the multi-gear electric drive transmission system is correspondingly meshed with the front axle differential input gear fixedly connected to the differential case of the front drive axle FR of the four-wheel drive vehicle, and the right half shaft 1 of the multi-gear electric drive transmission system is correspondingly meshed with the rear axle differential input gear fixedly connected to the differential case of the rear drive axle BA of the four-wheel drive vehicle, so as to realize the four-wheel drive driving mode of the vehicle.

[0181] Figure 5 Only by way of example, apply the transmission system shown in Embodiment 2 ( Figure 2 ) to a four-wheel drive vehicle. Similarly, the transmission system shown in Embodiment 1 ( Figure 1 ) or Embodiment 3 ( Figure 3 ) can also be applied to a four-wheel drive vehicle.

[0182] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A multi-speed electric drive transmission system, characterized in that: The transmission system includes: Motor EM; The output shaft of the motor EM outputs power to the shaft III through a two-stage reduction mechanism; Shaft III, which is a hollow shaft. From left to right on shaft III, there are sleeved with a first-gear driving gear, a third-gear driving gear, a second-gear driving gear, and a fourth-gear driving gear in sequence; Shaft IV, on which from left to right there are fixedly arranged a first-gear driven gear, a third-gear driven gear, a second-gear driven gear, a fourth-gear driven gear, and an output driving gear in sequence, wherein, the first-gear driven gear meshes with the first-gear driving gear correspondingly, the third-gear driven gear meshes with the third-gear driving gear correspondingly, the second-gear driven gear meshes with the second-gear driving gear correspondingly, and the fourth-gear driven gear meshes with the fourth-gear driving gear correspondingly; Differential, the differential includes a differential housing, and on the differential housing there is arranged an output driven gear that meshes with the output driving gear correspondingly; Clutch A, which is sleeved on shaft III and is located between the first-gear driving gear and the third-gear driving gear; Clutch B, which is sleeved on shaft III and is located between the second-gear driving gear and the fourth-gear driving gear; Differential lock DL, which is arranged on the left half shaft and is located between the fourth-gear driving gear and the output driven gear; The transmission system can achieve the following gears: Neutral gear N: Both clutch A and clutch B are in the middle position, and the differential lock DL is opened. At this time, it is in the neutral gear mode; 1.1) First mode of the first gear: Clutch A is combined on the left, clutch B is in the middle position, the differential lock DL is closed, and the left and right half shafts are locked; 1.2) Second mode of the first gear: Clutch A is combined on the left, clutch B is in the middle position, and the differential lock DL is opened; 2) Second gear: Clutch B is combined on the left, and clutch A is in the middle position; 3) Third gear: Clutch A is combined on the right, and clutch B is in the middle position; 4) Fourth gear: Clutch B is combined on the right, and clutch A is in the middle position.

2. The multi-speed electric drive transmission system according to claim 1, characterized in that: The transmission system further includes a shift drum and a shift execution mechanism, and the shift drum and the shift execution mechanism are respectively connected to clutch A, clutch B, and the differential lock DL.

3. A multi-speed electric drive transmission system according to any one of claims 1-2, characterized in that: The transmission system further includes: Shaft I, the output shaft of the motor EM is connected to the input driving gear through shaft I; Shaft II, on which there are fixedly arranged a second-stage driving gear and an input driven gear, wherein the input driven gear meshes with the input driving gear correspondingly; On the left side of the shaft III, there is fixedly arranged a second-stage driven gear that meshes with the second-stage driving gear correspondingly.

4. A multi-speed electric drive transmission system according to claim 3, characterized in that: Shaft I, shaft II, shaft III, and shaft IV are arranged parallel to each other, and the left half shaft and the right half shaft are concentric with shaft III.

5. A multi-speed electric drive transmission system according to claim 3, characterized in that: The transmission system further includes an oil pump shaft, on which there is fixedly arranged an oil pump gear that meshes with the second-stage driving gear correspondingly, and an oil pump is also connected to the oil pump shaft.

6. The multi-speed electric drive transmission system according to claim 1, wherein: The transmission system further includes a shift motor, the shift motor is connected to the shift drum and the shift execution mechanism and drives the shift drum to rotate through the shift execution mechanism. There are 3 sections of grooves on the surface of the shift drum to respectively control clutch A, clutch B, and the differential lock DL. The grooves drive the fork guide pins to realize gear shifting. The shift drum has a gear interlock function, and only one of clutch A and clutch B is in gear at the same time; The process of gear shifting for each corresponding gear of the transmission system is as follows: Under normal circumstances, clutch A is combined on the left, and when shifting from the N gear to the first gear, the vehicle starts; When shifting from the first gear to the second gear, the motor EM reduces torque. The shift motor drives the shift drum to rotate to control the clutch A to return to the middle position. Then, after the motor EM adjusts the speed so that the second-gear driving gear is synchronized with the engaging sleeve of the clutch B, the shift drum continues to rotate to control the clutch B to engage on the left. After the gear engagement is completed, the torque of the motor EM is restored, and the gear shift from the first gear to the second gear is completed. When shifting from the second gear to the third gear, the motor EM reduces torque. The shift motor drives the shift drum to rotate to control the clutch B to return to the middle position. Then, after the motor EM adjusts the speed so that the third-gear driving gear is synchronized with the engaging sleeve of the clutch A, the shift drum continues to rotate to control the clutch A to engage on the right. After the gear engagement is completed, the torque of the motor EM is restored, and the gear shift from the second gear to the third gear is completed. When shifting from the third gear to the fourth gear, the motor EM reduces torque. The shift motor drives the shift drum to rotate to control the clutch A to return to the middle position. Then, after the motor EM adjusts the speed so that the fourth-gear driving gear is synchronized with the engaging sleeve of the clutch B, the shift drum continues to rotate to control the clutch B to engage on the right. After the gear engagement is completed, the torque of the motor EM is restored, and the gear shift from the third gear to the fourth gear is completed. The downshift mode proceeds in the reverse of the above process. When a starting fault occurs where one side of the tires slips, the shift motor drives and controls the shift drum to actuate into the first mode of the first gear to lock the differential and thus increase the driving force of the vehicle.

7. A multi-speed electric drive transmission system, characterized in that: The transmission system includes: Motor EM; The output shaft of the motor EM outputs power to the shaft III through a two-stage reduction mechanism. Shaft III, and the shaft III is a hollow shaft. A two-stage driven gear, a second-gear driving gear, and a first-gear driving gear are sleeved on the shaft III from left to right in sequence. Shaft IV, and a third-gear driven gear, a second-gear driven gear, a first-gear driven gear, and an output driving gear are fixedly arranged on the shaft IV from left to right in sequence. Among them, the third-gear driven gear meshes with the two-stage driven gear correspondingly, the second-gear driven gear meshes with the second-gear driving gear correspondingly, and the first-gear driven gear meshes with the first-gear driving gear correspondingly. Differential, and the differential includes a differential housing. An output driven gear meshing with the output driving gear correspondingly is arranged on the differential housing. Clutch A, and the clutch A is arranged on the shaft IV and is located between the second-gear driven gear and the first-gear driven gear. Clutch B, and the clutch B is arranged on the shaft IV and is located between the third-gear driven gear and the second-gear driven gear. The transmission system can achieve the following gears: 1) First gear: The clutch A engages on the right, and the clutch B does not engage. 2) Second gear: The clutch A engages on the left, and the clutch B does not engage. 3) Third gear: The clutch A is in the middle position, and the clutch B engages on the left. 4) Neutral gear: The clutch A is in the middle position, and the clutch B does not engage.

8. A multi-gear electric drive transmission system according to claim 7, wherein: The transmission system further includes a shift drum and a shift actuator, and the shift drum and the shift actuator are respectively connected to the clutch A and the clutch B.

9. A multi-speed electric drive transmission system according to claim 7 or 8, characterized in that: The transmission system further includes: Shaft I, and the output shaft of the motor EM is connected to an input driving gear through the shaft I. Shaft II, and a two-stage driving gear and an input driven gear are fixedly arranged on the shaft II. Among them, the input driven gear meshes with the input driving gear correspondingly. A secondary driven gear that meshes with the secondary driving gear is fixedly arranged on the left side of the third shaft.

10. A multi-speed electric drive transmission system according to claim 9, characterized in that: The first shaft, the second shaft, the third shaft, and the fourth shaft are arranged in parallel, and the left half shaft and the right half shaft are concentric with the third shaft.

11. A multi-speed electric drive transmission system according to claim 7, characterized in that: The transmission system includes a shift motor, which is connected to a shift drum and a shift execution mechanism and drives the shift drum to rotate through the shift execution mechanism. Two grooves are arranged on the surface of the shift drum to respectively control clutch A and clutch B. The grooves drive the shift fork guide pins to achieve gear shifting. The shift drum has a gear interlock function, and only one of clutch A and clutch B is in gear at the same time. The corresponding gear shifting processes of the transmission system are as follows: When the vehicle starts, clutch A is combined on the right, and it is shifted from the N gear to the first gear to realize the vehicle start. When shifting from the first gear to the second gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position. Then, after the motor EM adjusts the speed to make the second gear driving gear synchronize with the engaging sleeve of clutch A, the shift drum continues to rotate to control clutch A to be combined on the left. After the gear combination is completed, the torque of the motor EM is restored to complete the gear shift from the first gear to the second gear. When shifting from the second gear to the third gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position. Then, after the motor EM adjusts the speed to make the third gear driving gear synchronize with the engaging sleeve of clutch B, the shift drum continues to rotate to control clutch B to be combined. After the gear combination is completed, the torque of the motor EM is restored to complete the gear shift from the second gear to the third gear. The downshift mode is carried out in the reverse direction of the above process.

12. A multi-speed electric drive transmission system, characterized in that: The transmission system includes: Motor EM; The output shaft of the motor EM outputs power to the third shaft through a two-stage reduction mechanism. The third shaft, which is a hollow shaft. A secondary driven gear, a second gear driving gear, and a first gear driving gear are sequentially sleeved on the third shaft from left to right. The fourth shaft. A third gear driven gear, a second gear driven gear, a first gear driven gear, and an output driving gear are sequentially and fixedly arranged on the fourth shaft from left to right. Among them, the third gear driven gear meshes with the secondary driven gear correspondingly, the second gear driven gear meshes with the second gear driving gear correspondingly, and the first gear driven gear meshes with the first gear driving gear correspondingly. Differential, which includes a differential housing. An output driven gear that meshes with the output driving gear is arranged on the differential housing. Clutch A, which is sleeved on the third shaft and is located between the first gear driving gear and the second gear driving gear. Clutch B, which is arranged on the fourth shaft and is located between the third gear driven gear and the second gear driven gear. The transmission system can achieve the following gears: 1) First gear: Clutch A is combined on the right, and clutch B is not combined. 2) Second gear: Clutch A is combined on the left, and clutch B is not combined. 3) Third gear: Clutch A is in the middle position, and clutch B is combined on the left. 4) N gear: Clutch A is in the middle position, and clutch B is not combined.

13. A multi-speed electric drive transmission system according to claim 12, characterized in that: The transmission system further includes a shift drum and a shift execution mechanism, which are respectively connected to clutch A and clutch B.

14. A multi-speed electric drive transmission system according to claim 12 or 13, characterized in that: The transmission system further includes: The first shaft, and the output shaft of the motor EM is connected to the input driving gear through the first shaft. The second shaft is fixedly provided with a secondary driving gear and an input driven gear thereon. Among them, the input driven gear is correspondingly meshed with the input driving gear; A secondary driven gear correspondingly meshed with the secondary driving gear is fixedly provided on the left side of the third shaft.

15. A multi-speed electric drive transmission system according to claim 14, characterized in that: The first shaft, the second shaft, the third shaft, and the fourth shaft are arranged parallel to each other, and the left half shaft and the right half shaft are concentrically arranged with the third shaft.

16. A multi-speed electric drive transmission system according to claim 15, characterized in that: The transmission system includes a shift motor. The shift motor is connected to a shift drum and a shift execution mechanism and drives the shift drum to rotate through the shift execution mechanism. Two sections of grooves are provided on the surface of the shift drum to respectively control clutch A and clutch B. The grooves drive the fork guide pins to achieve gear shifting. The shift drum has a gear interlock function, and only one of clutch A and clutch B is in gear at the same time; The corresponding gear shifting process of the transmission system is as follows: When the vehicle starts, clutch A is combined on the right, and it is shifted from N gear to 1 gear to achieve vehicle start; When shifting from 1 gear to 2 gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position; then after the motor EM adjusts the speed to synchronize the second gear driving gear with the engagement sleeve of clutch A, the shift drum continues to rotate to control clutch A to be combined on the left. After the gear is combined, the torque of the motor EM is restored to complete the gear shift from 1 gear to 2 gear; When shifting from 2 gear to 3 gear, the motor EM reduces torque, and the shift motor drives the shift drum to rotate to control clutch A to return to the middle position; then after the motor EM adjusts the speed to synchronize the third gear driving gear with the engagement sleeve of clutch B, the shift drum continues to rotate to control clutch B to be combined on the left. After the gear is combined, the torque of the motor EM is restored to complete the gear shift from 2 gear to 3 gear; The downshift mode proceeds in the reverse direction of the above process.

17. A four-wheel drive vehicle using a multi-speed electric drive transmission system according to any one of claims 1-16, characterized in that: The left half shaft of the multi-speed electric drive transmission system is correspondingly meshed with the front axle differential input gear fixedly connected to the differential case of the front drive axle of the four-wheel drive vehicle, and the right half shaft of the multi-speed electric drive transmission system is correspondingly meshed with the rear axle differential input gear fixedly connected to the differential case of the rear drive axle of the four-wheel drive vehicle.

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