1. A multi-gear electric drive transmission system is characterized in that: the transmission system includes:

an electric machine EM (6);

an output shaft of the motor EM (6) outputs power to a shaft III (8) through a secondary speed reducing mechanism;

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 sequentially sleeved on the shaft III (8) from left to right;

the driving mechanism comprises an IV shaft (26), wherein 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 on the IV shaft (26) from left to right in sequence, the first-gear driven gear (16) is correspondingly meshed with a first-gear driving gear (15), the third-gear driven gear (18) is correspondingly meshed with a third-gear driving gear (17), the second-gear driven gear (20) is correspondingly meshed with a second-gear driving gear (19), and the fourth-gear driven gear (21) is correspondingly meshed with a fourth-gear driving gear (22);

the differential comprises a differential shell (3), and an output driven gear (24) which is correspondingly meshed with an output driving gear (23) is arranged on the differential shell (3);

a differential lock DL (4) disposed on the left half shaft (25) and between the fourth drive gear (22) and the output driven gear (24);

the clutch A (7) is sleeved on the shaft III (8) and is positioned between the first-gear driving gear (15) and the third-gear driving gear (17);

the clutch B (5) is sleeved on the shaft III (8) and positioned between the second-gear driving gear (19) and the fourth-gear driving gear (22);

and the gear shifting drum and the gear shifting actuating mechanism (27) are respectively connected with the clutch A (7), the clutch B (5) and the differential lock DL (4).

2. A multi-range electric drive transmission system as defined in claim 1, wherein: the transmission system further includes:

the output shaft of the motor EM (6) is connected with an input driving gear (13) through the shaft I;

the shaft II is fixedly provided with a secondary driving gear (11) and an input driven gear (14), wherein the input driven gear (14) is correspondingly meshed with the input driving gear (13);

and a secondary driven gear (9) correspondingly meshed with a secondary driving gear (11) is fixedly arranged on the left side of the shaft III (8).

3. A multi-range electric drive transmission system according to claim 1 or 2, wherein: 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 arranged concentrically with the shaft III (8).

4. A multi-range electric drive transmission system as defined in claim 2, wherein: the transmission system further comprises an oil pump shaft, an oil pump gear (12) which is correspondingly meshed with the secondary driving gear (11) is fixedly arranged on the oil pump shaft, and an oil pump (10) is further connected to the oil pump shaft.

5. A multi-range electric drive transmission system according to claim 1 or 2, wherein: the transmission system can realize the following gears:

neutral gear N: the clutch A and the clutch B are both positioned in the middle position, the differential lock DL is opened, and the neutral mode is adopted at the moment;

1.1) 1 st gear first mode: the clutch A is combined at the left, the clutch B is positioned at the middle position, the differential lock DL is closed, and the left half shaft and the right half shaft are locked;

1.2) second mode of 1 st gear: the clutch A is combined at the left, the clutch B is positioned at the middle position, and the differential lock DL is opened;

2) and 2, gear: the clutch B is combined at the left, and the clutch A is positioned at the middle position;

3) and 3, gear shifting: the clutch A is combined right, and the clutch B is positioned in a middle position;

4) 4, gear shifting: the clutch B is combined at the right, and the clutch A is positioned at the middle position.

6. A multi-range electric drive transmission system according to claim 5, wherein: the transmission system comprises a gear shifting motor, the gear shifting motor is connected with a gear shifting drum and a gear shifting executing mechanism (27) and drives the gear shifting drum to rotate through the gear shifting executing mechanism, 3 sections of grooves are formed in the surface of the gear shifting drum to respectively and correspondingly control a clutch A, a clutch B and a differential lock DL, the grooves drive a shifting fork guide pin to realize gear conversion, the gear shifting drum has a gear interlocking function, and only one of the clutch A and the clutch B is in gear at the same time;

the corresponding gear conversion process of the transmission system comprises the following steps:

under the normal condition, the clutch A is combined on the left, and the gear 1 is engaged from the gear N to realize the starting of the vehicle;

when the 1 gear is shifted and the 2 gear is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a second-gear driving gear is synchronous with a clutch B meshing sleeve, the gear shifting drum continues to rotate to control the clutch B to be combined on the left side, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from the first gear to the second gear;

when the gear 2 is shifted and the gear 3 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch B to return to the middle position; then the motor EM adjusts the speed until a three-gear driving gear and a clutch A meshing sleeve are synchronous, the gear shifting drum continues to rotate to control the clutch A to be combined on the right, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 2-gear to 3-gear;

when the gear 3 is shifted and the gear 4 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a four-gear driving gear is synchronous with a clutch B meshing sleeve, the gear shifting drum continues to rotate to control the clutch B to be combined on the right, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 3 gears to 4 gears;

the downshift mode is performed in reverse to the above process;

when a starting fault that one side of a tire slips occurs, the gear shifting motor drives and controls the gear shifting drum to act to enter a 1-gear first mode so as to realize locking of the differential mechanism and further improve the driving force of the vehicle.

7. A multi-gear electric drive transmission system is characterized in that: the transmission system includes:

an electric machine EM (6);

an output shaft of the motor EM (6) outputs power to a secondary driven gear (9) of the shaft III (8) through a secondary speed reducing mechanism;

the shaft III is a hollow shaft, a secondary driven gear (9), a secondary driving gear (19) and a first-gear driving gear (15) are sequentially sleeved on the shaft III from left to right, and the secondary driven gear (9) is correspondingly meshed with the secondary driving gear (11);

the driving gear assembly comprises an IV shaft (26), wherein 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 IV shaft from left to right in sequence, the third-gear driven gear (18) is correspondingly meshed with a second-stage driven gear (9), the second-gear driven gear (20) is correspondingly meshed with a second-gear driving gear (19), and the first-gear driven gear (16) is correspondingly meshed with a first-gear driving gear (15);

the differential comprises a differential shell (3), and an output driven gear (24) which is correspondingly meshed with an output driving gear (23) is arranged on the differential shell (3);

the clutch A (7) is arranged on the IV shaft (26) and is positioned between the second-gear driven gear (20) and the first-gear driven gear (16); the clutch A (7) comprises a three-gear hub (71) and a three-gear meshing sleeve (72);

the clutch B (5) is arranged on the IV shaft (26) and is positioned between the third-gear driven gear (18) and the second-gear driven gear (20); the clutch B (5) comprises a second gear hub (51) and a second gear meshing sleeve (52);

the gear shifting drum and the gear shifting actuating mechanism are respectively connected with the clutch A (7) and the clutch B (5).

8. A multi-range electric drive transmission system according to claim 7, wherein: the transmission system further includes:

the output shaft of the motor EM (6) is connected with an input driving gear (13) through the shaft I;

the shaft II is fixedly provided with a secondary driving gear (11) and an input driven gear (14), wherein the input driven gear (14) is correspondingly meshed with the input driving gear (13);

and a secondary driven gear (9) correspondingly meshed with a secondary driving gear (11) is fixedly arranged on the left side of the shaft III (8).

9. A multi-range electric drive transmission system according to claim 7 or 8, wherein: 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 arranged concentrically with the shaft III.

10. A multi-range electric drive transmission system according to claim 7 or 8, wherein: the transmission system can realize the following gears:

1) 1, gear 1: the clutch A is combined on the right, and the clutch B is not combined;

2) and 2, gear: the clutch A is combined on the left, and the clutch B is not combined;

3) and 3, gear shifting: the clutch A is positioned in the middle position, and the clutch B is combined on the left side;

4) n is kept: clutch a is in the neutral position and clutch B is not engaged.

11. A multi-range electric drive transmission system according to claim 7 or 8, wherein: the transmission system comprises a gear shifting motor, the gear shifting motor is connected with a gear shifting drum and a gear shifting executing mechanism and drives the gear shifting drum to rotate through the gear shifting executing mechanism, 2 sections of grooves are formed in the surface of the gear shifting drum to respectively correspondingly control a clutch A and a clutch B, the grooves drive a shifting fork guide pin to realize gear conversion, the gear shifting drum has a gear interlocking function, and only one of the clutch A and the clutch B is in gear at the same time;

the corresponding gear conversion process of the transmission system comprises the following steps:

when the vehicle starts, the clutch A is combined to the right, and the gear 1 is engaged from the gear N to realize the vehicle start;

when the 1 gear is shifted and the 2 gear is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a second-gear driving gear is synchronous with the meshing sleeve of the clutch A, the gear shifting drum continues to rotate to control the clutch A to be combined on the left, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from the first gear to the second gear;

when the gear 2 is shifted and the gear 3 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a three-gear driving gear and a clutch B meshing sleeve are synchronous, the gear shifting drum continues to rotate to control the clutch B to be combined, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 2-gear to 3-gear;

the downshift mode proceeds in reverse of the above process.

12. A multi-gear electric drive transmission system is characterized in that: the transmission system includes:

an electric machine EM (6);

an output shaft of the motor EM (6) outputs power to a secondary driven gear (9) of the shaft III (8) through a secondary speed reducing mechanism;

the shaft III is a hollow shaft, a secondary driven gear (9), a secondary driving gear (19) and a first-gear driving gear (15) are sequentially sleeved on the shaft III from left to right, and the secondary driven gear (9) is correspondingly meshed with the secondary driving gear (11);

the driving gear assembly comprises an IV shaft (26), wherein 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 IV shaft from left to right in sequence, the third-gear driven gear (18) is correspondingly meshed with a second-stage driven gear (9), the second-gear driven gear (20) is correspondingly meshed with a second-gear driving gear (19), and the first-gear driven gear (16) is correspondingly meshed with a first-gear driving gear (15);

the differential comprises a differential shell (3), and an output driven gear (24) which is correspondingly meshed with an output driving gear (23) is arranged on the differential shell (3);

the clutch A (7) is sleeved on the shaft III (8) and is positioned between the first-gear driving gear (15) and the second-gear driving gear (19); the clutch A (7) comprises a three-gear hub (71) and a three-gear meshing sleeve (72);

the clutch B (5) is arranged on the IV shaft (26) and is positioned between the third-gear driven gear (18) and the second-gear driven gear (20); the clutch B (5) comprises a second gear hub (51) and a second gear meshing sleeve (52);

the gear shifting drum and the gear shifting actuating mechanism are respectively connected with the clutch A (7) and the clutch B (5).

13. A multi-range electric drive transmission system according to claim 12, wherein: the transmission system further includes:

the output shaft of the motor EM (6) is connected with an input driving gear (13) through the shaft I;

the shaft II is fixedly provided with a secondary driving gear (11) and an input driven gear (14), wherein the input driven gear (14) is correspondingly meshed with the input driving gear (13);

and a secondary driven gear (9) correspondingly meshed with a secondary driving gear (11) is fixedly arranged on the left side of the shaft III (8).

14. A multi-range electric drive transmission system according to claim 12 or 13, wherein: 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 arranged concentrically with the shaft III.

15. A multi-range electric drive transmission system according to claim 12 or 13, wherein: the transmission system can realize the following gears:

1) 1, gear 1: the clutch A is combined on the right, and the clutch B is not combined;

2) and 2, gear: the clutch A is combined on the left, and the clutch B is not combined;

3) and 3, gear shifting: the clutch A is positioned in the middle position, and the clutch B is combined on the left side;

4) n is kept: clutch a is in the neutral position and clutch B is not engaged.

16. A multi-range electric drive transmission system according to claim 12 or 13, wherein: the transmission system comprises a gear shifting motor, the gear shifting motor is connected with a gear shifting drum and a gear shifting executing mechanism and drives the gear shifting drum to rotate through the gear shifting executing mechanism, 2 sections of grooves are formed in the surface of the gear shifting drum to respectively correspondingly control a clutch A and a clutch B, the grooves drive a shifting fork guide pin to realize gear conversion, the gear shifting drum has a gear interlocking function, and only one of the clutch A and the clutch B is in gear at the same time;

the corresponding gear conversion process of the transmission system comprises the following steps:

when the vehicle starts, the clutch A is combined to the right, and the gear 1 is engaged from the gear N to realize the vehicle start;

when the 1 gear is shifted and the 2 gear is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a second-gear driving gear is synchronous with the meshing sleeve of the clutch A, the gear shifting drum continues to rotate to control the clutch A to be combined on the left, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from the first gear to the second gear;

when the gear 2 is shifted and the gear 3 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a three-gear driving gear and a clutch B meshing sleeve are synchronous, the gear shifting drum continues to rotate to control the clutch B to be combined on the left, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 2-gear to 3-gear;

the downshift mode proceeds in reverse of the above process.

17. A four-wheel drive vehicle employing a multiple gear electric drive transmission system as defined in any one of claims 1 to 16, wherein: the left half shaft (25) of the multi-gear electric drive transmission system is correspondingly meshed with a front axle differential input gear fixedly connected to a differential shell of a 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 a rear axle differential input gear fixedly connected to a differential shell of a rear drive axle (BA) of the four-wheel drive vehicle.

Background

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

One of the commercial vehicle electric drive axles adopted in the market at present is that a single motor is combined with a traditional AMT (automated mechanical transmission), a low-speed and high-torque motor is applied, although the structure is simple, the weight is heavy, the unsprung mass is large, the vibration is aggravated, and the reliability problem is caused, and meanwhile, the application working conditions of a plurality of commercial vehicles need larger motors to provide enough power; in addition, the input and output structure is offset, and the vehicle is not easy to arrange; the other adopts a double-motor structure (such as CN108001185A and CN 108725178A), solves the weight problem, but has high cost and cannot be accepted by the market due to the fact that one set of motor and electric control equipment are additionally arranged.

Disclosure of Invention

In order to overcome the defects and shortcomings in the prior art, the invention provides a multi-gear electric drive axle transmission system.

The technical scheme provided by the invention is as follows: a multi-speed electric drive transmission system, the transmission system comprising:

an electric machine EM (6);

an output shaft of the motor EM (6) outputs power to a shaft III (8) through a secondary speed reducing mechanism;

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 sequentially sleeved on the shaft III (8) from left to right;

the driving mechanism comprises an IV shaft (26), wherein 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 on the IV shaft (26) from left to right in sequence, the first-gear driven gear (16) is correspondingly meshed with a first-gear driving gear (15), the third-gear driven gear (18) is correspondingly meshed with a third-gear driving gear (17), the second-gear driven gear (20) is correspondingly meshed with a second-gear driving gear (19), and the fourth-gear driven gear (21) is correspondingly meshed with a fourth-gear driving gear (22);

the differential comprises a differential shell (3), and an output driven gear (24) which is correspondingly meshed with an output driving gear (23) is arranged on the differential shell (3);

a differential lock DL (4) disposed on the left half shaft (25) and between the fourth drive gear (22) and the output driven gear (24);

the clutch A (7) is sleeved on the shaft III (8) and is positioned between the first-gear driving gear (15) and the third-gear driving gear (17);

the clutch B (5) is sleeved on the shaft III (8) and positioned between the second-gear driving gear (19) and the fourth-gear driving gear (22);

and the gear shifting drum and the gear shifting actuating mechanism (27) are respectively connected with the clutch A (7), the clutch B (5) and the differential lock DL (4).

Further, the transmission system further includes:

the output shaft of the motor EM (6) is connected with an input driving gear (13) through the shaft I;

the shaft II is fixedly provided with a secondary driving gear (11) and an input driven gear (14), wherein the input driven gear (14) is correspondingly meshed with the input driving gear (13);

and a secondary driven gear (9) correspondingly meshed with a secondary driving gear (11) is fixedly arranged on the left side of the shaft III (8).

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 arranged concentrically with the shaft III (8).

Furthermore, the transmission system further comprises an oil pump shaft, an oil pump gear (12) which is correspondingly meshed with the secondary driving gear (11) is fixedly arranged on the oil pump shaft, and an oil pump (10) is further connected to the oil pump shaft.

Further, the transmission system can realize the following gears:

neutral gear N: the clutch A and the clutch B are both positioned in the middle position, the differential lock DL is opened, and the neutral mode is adopted at the moment;

1.1) 1 st gear first mode: the clutch A is combined at the left, the clutch B is positioned at the middle position, the differential lock DL is closed, and the left half shaft and the right half shaft are locked;

1.2) second mode of 1 st gear: the clutch A is combined at the left, the clutch B is positioned at the middle position, and the differential lock DL is opened;

2) and 2, gear: the clutch B is combined at the left, and the clutch A is positioned at the middle position;

3) and 3, gear shifting: the clutch A is combined right, and the clutch B is positioned in a middle position;

4) 4, gear shifting: the clutch B is combined at the right, and the clutch A is positioned at the middle position.

Furthermore, the transmission system comprises a gear shifting motor, the gear shifting motor is connected with a gear shifting drum and a gear shifting executing mechanism (27) and drives the gear shifting drum to rotate through the gear shifting executing mechanism, 3 sections of grooves are formed in the surface of the gear shifting drum to respectively correspondingly control a clutch A, a clutch B and a differential lock DL, the grooves drive a shifting fork guide pin to realize gear conversion, the gear shifting drum has a gear interlocking function, and only one clutch A and one clutch B are in gear at the same time;

the corresponding gear conversion process of the transmission system comprises the following steps:

under the normal condition, the clutch A is combined on the left, and the gear 1 is engaged from the gear N to realize the starting of the vehicle;

when the 1 gear is shifted and the 2 gear is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a second-gear driving gear is synchronous with a clutch B meshing sleeve, the gear shifting drum continues to rotate to control the clutch B to be combined on the left side, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from the first gear to the second gear;

when the gear 2 is shifted and the gear 3 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch B to return to the middle position; then the motor EM adjusts the speed until a three-gear driving gear and a clutch A meshing sleeve are synchronous, the gear shifting drum continues to rotate to control the clutch A to be combined on the right, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 2-gear to 3-gear;

when the gear 3 is shifted and the gear 4 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a four-gear driving gear is synchronous with a clutch B meshing sleeve, the gear shifting drum continues to rotate to control the clutch B to be combined on the right, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 3 gears to 4 gears;

the downshift mode is performed in reverse to the above process;

when a starting fault that one side of a tire slips occurs, the gear shifting motor drives and controls the gear shifting drum to act to enter a 1-gear first mode so as to realize locking of the differential mechanism and further improve the driving force of the vehicle.

Further, a multi-gear electric drive transmission system is also proposed, the transmission system comprising:

an electric machine EM (6);

an output shaft of the motor EM (6) outputs power to a secondary driven gear (9) of the shaft III (8) through a secondary speed reducing mechanism;

the shaft III is a hollow shaft, a secondary driven gear (9), a secondary driving gear (19) and a first-gear driving gear (15) are sequentially sleeved on the shaft III from left to right, and the secondary driven gear (9) is correspondingly meshed with the secondary driving gear (11);

the driving gear assembly comprises an IV shaft (26), wherein 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 IV shaft from left to right in sequence, the third-gear driven gear (18) is correspondingly meshed with a second-stage driven gear (9), the second-gear driven gear (20) is correspondingly meshed with a second-gear driving gear (19), and the first-gear driven gear (16) is correspondingly meshed with a first-gear driving gear (15);

the differential comprises a differential shell (3), and an output driven gear (24) which is correspondingly meshed with an output driving gear (23) is arranged on the differential shell (3);

the clutch A (7) is arranged on the IV shaft (26) and is positioned between the second-gear driven gear (20) and the first-gear driven gear (16); the clutch A (7) comprises a three-gear hub (71) and a three-gear meshing sleeve (72);

the clutch B (5) is arranged on the IV shaft (26) and is positioned between the third-gear driven gear (18) and the second-gear driven gear (20); the clutch B (5) comprises a second gear hub (51) and a second gear meshing sleeve (52);

the gear shifting drum and the gear shifting actuating mechanism are respectively connected with the clutch A (7) and the clutch B (5).

Further, the transmission system further includes:

the output shaft of the motor EM (6) is connected with an input driving gear (13) through the shaft I;

the shaft II is fixedly provided with a secondary driving gear (11) and an input driven gear (14), wherein the input driven gear (14) is correspondingly meshed with the input driving gear (13);

and a secondary driven gear (9) correspondingly meshed with a secondary driving gear (11) is fixedly arranged on the left side of the shaft III (8).

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 arranged concentrically with the shaft III.

Further, the transmission system can realize the following gears:

1) 1, gear 1: the clutch A is combined on the right, and the clutch B is not combined;

2) and 2, gear: the clutch A is combined on the left, and the clutch B is not combined;

3) and 3, gear shifting: the clutch A is positioned in the middle position, and the clutch B is combined on the left side;

4) n is kept: clutch a is in the neutral position and clutch B is not engaged.

Furthermore, the transmission system comprises a gear shifting motor, the gear shifting motor is connected with a gear shifting drum and a gear shifting executing mechanism and drives the gear shifting drum to rotate through the gear shifting executing mechanism, 2 sections of grooves are formed in the surface of the gear shifting drum to respectively correspondingly control a clutch A and a clutch B, the grooves drive a shifting fork guide pin to realize gear conversion, the gear shifting drum has a gear interlocking function, and only one clutch A and one clutch B are in gear at the same time;

the corresponding gear conversion process of the transmission system comprises the following steps:

when the vehicle starts, the clutch A is combined to the right, and the gear 1 is engaged from the gear N to realize the vehicle start;

when the 1 gear is shifted and the 2 gear is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a second-gear driving gear is synchronous with the meshing sleeve of the clutch A, the gear shifting drum continues to rotate to control the clutch A to be combined on the left, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from the first gear to the second gear;

when the gear 2 is shifted and the gear 3 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a three-gear driving gear and a clutch B meshing sleeve are synchronous, the gear shifting drum continues to rotate to control the clutch B to be combined, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 2-gear to 3-gear;

the downshift mode proceeds in reverse of the above process.

Further, a multi-gear electric drive transmission system is also proposed, the transmission system comprising:

an electric machine EM (6);

an output shaft of the motor EM (6) outputs power to a secondary driven gear (9) of the shaft III (8) through a secondary speed reducing mechanism;

the shaft III is a hollow shaft, a secondary driven gear (9), a secondary driving gear (19) and a first-gear driving gear (15) are sequentially sleeved on the shaft III from left to right, and the secondary driven gear (9) is correspondingly meshed with the secondary driving gear (11);

the driving gear assembly comprises an IV shaft (26), wherein 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 IV shaft from left to right in sequence, the third-gear driven gear (18) is correspondingly meshed with a second-stage driven gear (9), the second-gear driven gear (20) is correspondingly meshed with a second-gear driving gear (19), and the first-gear driven gear (16) is correspondingly meshed with a first-gear driving gear (15);

the differential comprises a differential shell (3), and an output driven gear (24) which is correspondingly meshed with an output driving gear (23) is arranged on the differential shell (3);

the clutch A (7) is sleeved on the shaft III (8) and is positioned between the first-gear driving gear (15) and the second-gear driving gear (19); the clutch A (7) comprises a three-gear hub (71) and a three-gear meshing sleeve (72);

the clutch B (5) is arranged on the IV shaft (26) and is positioned between the third-gear driven gear (18) and the second-gear driven gear (20); the clutch B (5) comprises a second gear hub (51) and a second gear meshing sleeve (52);

the gear shifting drum and the gear shifting actuating mechanism are respectively connected with the clutch A (7) and the clutch B (5).

Further, the transmission system further includes:

the output shaft of the motor EM (6) is connected with an input driving gear (13) through the shaft I;

the shaft II is fixedly provided with a secondary driving gear (11) and an input driven gear (14), wherein the input driven gear (14) is correspondingly meshed with the input driving gear (13);

and a secondary driven gear (9) correspondingly meshed with a secondary driving gear (11) is fixedly arranged on the left side of the shaft III (8).

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 arranged concentrically with the shaft III.

Further, the transmission system can realize the following gears:

1) 1, gear 1: the clutch A is combined on the right, and the clutch B is not combined;

2) and 2, gear: the clutch A is combined on the left, and the clutch B is not combined;

3) and 3, gear shifting: the clutch A is positioned in the middle position, and the clutch B is combined on the left side;

4) n is kept: clutch a is in the neutral position and clutch B is not engaged.

Furthermore, the transmission system comprises a gear shifting motor, the gear shifting motor is connected with a gear shifting drum and a gear shifting executing mechanism and drives the gear shifting drum to rotate through the gear shifting executing mechanism, 2 sections of grooves are formed in the surface of the gear shifting drum to respectively correspondingly control a clutch A and a clutch B, the grooves drive a shifting fork guide pin to realize gear conversion, the gear shifting drum has a gear interlocking function, and only one clutch A and one clutch B are in gear at the same time;

the corresponding gear conversion process of the transmission system comprises the following steps:

when the vehicle starts, the clutch A is combined to the right, and the gear 1 is engaged from the gear N to realize the vehicle start;

when the 1 gear is shifted and the 2 gear is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a second-gear driving gear is synchronous with the meshing sleeve of the clutch A, the gear shifting drum continues to rotate to control the clutch A to be combined on the left, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from the first gear to the second gear;

when the gear 2 is shifted and the gear 3 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a three-gear driving gear and a clutch B meshing sleeve are synchronous, the gear shifting drum continues to rotate to control the clutch B to be combined on the left, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 2-gear to 3-gear;

the downshift mode proceeds in reverse of the above process.

Further, the present invention provides a four-wheel drive vehicle using the above-mentioned multi-gear electric drive transmission system, characterized in that: the left half shaft of the multi-gear electric drive transmission system is correspondingly meshed with a front axle differential input gear fixedly connected to a differential shell of a front drive axle of the four-wheel drive vehicle, and the right half shaft of the multi-gear electric drive transmission system is correspondingly meshed with a rear axle differential input gear fixedly connected to a differential shell of a rear drive axle of the four-wheel drive vehicle.

Compared with the prior art, the invention has the following beneficial effects:

1) the invention provides a multi-gear electric drive axle transmission system, a motor and a gearbox are integrated, and the space is compact; the shaft III and the differential are designed concentrically, and a power transmission path returns to the shaft III from the shaft IV, so that the offset is reduced; the shaft III and the left half shaft are designed by a shaft sleeve shaft, and the left half shaft passes through the shaft III to be output; one shift actuator controls 3 clutches; each gear is rotated through the shift drum, and the order is shifted, realizes gear mechanical interlocking, has improved the security, has reduced the control degree of difficulty.

2) The invention provides a multi-gear electric drive axle transmission system, which omits links such as a clutch, a transmission shaft, a universal joint and the like, and optimizes the transmission efficiency; the transmission gear pair and the main reduction gear pair are driven by cylindrical gears, and the system efficiency is high.

3) The invention provides a multi-gear electric drive axle transmission system, wherein a clutch A is positioned on a shaft III, compared with a scheme that the clutch A is positioned on a shaft IV, the synchronous inertia is smaller when a first gear and a second gear are changed, the synchronous time of a motor is shorter, and the relative gear shifting speed is faster.

Drawings

Fig. 1 is a schematic structural diagram of a first embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a second embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a third embodiment of the present invention.

Fig. 4 is a schematic view of the shift drum surface groove under various working conditions in the first embodiment of the present invention.

Fig. 5 is a schematic structural view of a four-wheel drive vehicle employing a multi-speed electric drive transmission system according to the first, second, or third embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "both ends", "one end", "the other end", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "connected," and the like are to be construed broadly, such as "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Referring to fig. 1, a multi-gear electric drive transmission system according to a first embodiment of the present invention includes: electric machine EM 6;

the output shaft of the motor EM6 is connected with the input driving gear 13 through the shaft I;

the shaft II is fixedly provided with a secondary driving gear 11 and an input driven gear 14, wherein the input driven gear 14 is correspondingly meshed with the input driving gear 13;

the shaft III is a hollow shaft, a second-stage driven gear 9 correspondingly meshed with a second-stage driving gear 11 is fixedly arranged on the left side of the shaft III, and a first-stage driving gear 15, a third-stage driving gear 17, a second-stage driving gear 19 and a fourth-stage driving gear 22 are sequentially sleeved on the right side of the shaft III from left to right;

the IV shaft 26 is fixedly provided with 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 from left to right, wherein the first-gear driven gear 16 is correspondingly meshed with the first-gear driving gear 15, the third-gear driven gear 18 is correspondingly meshed with the third-gear driving gear 17, the second-gear driven gear 20 is correspondingly meshed with the second-gear driving gear 19, and the fourth-gear driven gear 21 is correspondingly meshed with the fourth-gear driving gear 22;

the differential mechanism comprises a differential mechanism shell 3, an output driven gear 24 which is correspondingly meshed with an output driving gear 23 is arranged on the differential mechanism shell 3, a left half shaft 25 of the differential mechanism is concentric with a shaft III and penetrates through the inside of the shaft III to output power to a left wheel of a vehicle, a right half shaft 1 of the differential mechanism outputs power to a right wheel of the vehicle, the left half shaft 25 and the right half shaft 1 are respectively connected with a half shaft gear inside the differential mechanism, and the half shaft gear is meshed with a differential mechanism planetary gear 2;

the oil pump comprises an oil pump shaft, wherein an oil pump gear 12 correspondingly meshed with a secondary driving gear 11 is fixedly arranged on the oil pump shaft, and an oil pump 10 is also connected to the oil pump shaft;

a differential lock DL4 disposed on the left half shaft 25 between the fourth driving gear 22 and the output driven gear 24;

the clutch A7 is sleeved on the shaft III 8 and is positioned between the first-gear driving gear 15 and the third-gear driving gear 17;

the clutch B5 is sleeved on the shaft III 8 and is positioned between the second-gear driving gear 19 and the fourth-gear driving gear 22;

and a shift drum and shift actuator 27, wherein the shift drum and shift actuator 27 is connected with the clutch a7, the clutch B5 and the differential lock DL4 respectively.

Specifically, the shaft i, the shaft ii, the shaft iii 8, and the shaft iv 26 are arranged in parallel with each other, and the left half shaft 25 and the right half shaft 1 are arranged concentrically with the shaft iii.

In particular, the transmission system is capable of achieving the following gears (as shown in table 1):

table 1 operation table of clutch and differential lock corresponding to each gear according to the first embodiment of the present invention

Note: and V is the corresponding working position of the corresponding clutch and the differential lock under each gear.

Neutral gear N: the clutch A and the clutch B are both positioned in the middle position, the differential lock DL is opened, and the neutral mode is adopted at the moment;

1.1) 1 st gear first mode: the clutch A is combined at the left, the clutch B is positioned at the middle position, the differential lock DL is closed, and the left half shaft and the right half shaft are locked;

1.2) second mode of 1 st gear: the clutch A is combined at the left, the clutch B is positioned at the middle position, and the differential lock DL is opened;

2) and 2, gear: the clutch B is combined at the left, and the clutch A is positioned at the middle position;

3) and 3, gear shifting: the clutch A is combined right, and the clutch B is positioned in a middle position;

4) 4, gear shifting: the clutch B is combined at the right, and the clutch A is positioned at the middle position.

Specifically, the transmission system comprises a gear shifting motor, the gear shifting motor is connected with a gear shifting drum and a gear shifting executing mechanism (27) and drives the gear shifting drum to rotate through the gear shifting executing mechanism, 3 sections of grooves are formed in the surface of the gear shifting drum to respectively and correspondingly control a clutch A, a clutch B and a differential lock DL, the grooves drive a shifting fork guide pin to realize gear conversion, the gear shifting drum has a gear interlocking function, and only one clutch A and one clutch B are in gear at the same time;

referring to fig. 4, each corresponding gear shifting process of the transmission system is as follows:

under the normal condition, the clutch A is combined on the left side, and the 1 gear is engaged, so that the vehicle starts;

when the 1 gear is shifted and the 2 gear is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a second-gear driving gear is synchronous with a clutch B meshing sleeve, the gear shifting drum continues to rotate to control the clutch B to be combined on the left side, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from the first gear to the second gear;

when the gear 2 is shifted and the gear 3 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch B to return to the middle position; then the motor EM adjusts the speed until a three-gear driving gear and a clutch A meshing sleeve are synchronous, the gear shifting drum continues to rotate to control the clutch A to be combined on the right, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 2-gear to 3-gear;

when the gear 3 is shifted and the gear 4 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a four-gear driving gear is synchronous with a clutch B meshing sleeve, the gear shifting drum continues to rotate to control the clutch B to be combined on the right, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 3 gears to 4 gears;

the downshift mode is performed in reverse to the above process;

when a starting fault that one side of a tire slips occurs, the gear shifting motor drives and controls the gear shifting drum to act to enter a 1-gear first mode so as to realize locking of the differential mechanism and further improve the driving force of the vehicle.

In the first embodiment, the motor and the gearbox are designed integrally, so that the space is compact; the shaft III and the differential are designed concentrically, and a power transmission path returns to the shaft III from the shaft IV, so that the offset is reduced; the shaft III and the left half shaft are designed by a shaft sleeve shaft, and the left half shaft passes through the shaft III to be output; one shift actuator controls 3 clutches; each gear is rotated through the shift drum, and the order is shifted, realizes gear mechanical interlocking, has improved the security, has reduced the control degree of difficulty.

Referring to fig. 2, a multi-speed electric drive transmission system according to a second embodiment of the present invention includes: electric machine EM 6;

the output shaft of the motor EM6 is connected with the input driving gear 13 through the shaft I;

the shaft II is fixedly provided with a secondary driving gear 11 and an input driven gear 14, wherein the input driven gear 14 is correspondingly meshed with the input driving gear 13;

the shaft III is a hollow shaft, a secondary driven gear 9, a secondary driving gear 19 and a first-gear driving gear 15 are sequentially sleeved on the shaft III from left to right, and the secondary driven gear 9 is correspondingly meshed with a secondary driving gear 11;

the IV shaft 26 is fixedly provided with a third-gear driven gear 18, a second-gear driven gear 20, a first-gear driven gear 16 and an output driving gear 23 from left to right, wherein the third-gear driven gear 18 is correspondingly meshed with the second-stage driven gear 9, the second-gear driven gear 20 is correspondingly meshed with the second-gear driving gear 19, and the first-gear driven gear 16 is correspondingly meshed with the first-gear driving gear 15;

the differential mechanism comprises a differential mechanism shell 3, an output driven gear 24 which is correspondingly meshed with an output driving gear 23 is arranged on the differential mechanism shell 3, a left half shaft 25 of the differential mechanism is concentric with a shaft III and penetrates through the inside of the shaft III to output power to a left wheel of a vehicle, a right half shaft 1 of the differential mechanism outputs power to a right wheel of the vehicle, the left half shaft 25 and the right half shaft 1 are respectively connected with a half shaft gear inside the differential mechanism, and the half shaft gear is meshed with a differential mechanism planetary gear;

a clutch A7 disposed on the IV shaft 26 between the second gear driven gear 20 and the first gear driven gear 16; the clutch A7 comprises a third-gear hub 71 and a third-gear engaging sleeve 72;

a clutch B5 disposed on the iv shaft 26 between the third driven gear 18 and the second driven gear 20; the clutch B5 comprises a first-gear hub 51 and a first-gear engaging sleeve 52;

the gear shifting drum and the gear shifting actuating mechanism are respectively connected with the clutch A7 and the clutch B5;

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 arranged concentrically with the shaft III.

In particular, the transmission system is capable of achieving the following gears (as shown in table 2):

TABLE 2 Clutch actuation Table for each gear in the second embodiment of the present invention

Note: and V is the corresponding working position of the corresponding clutch under each gear.

1) 1, gear 1: the clutch A is combined on the right, and the clutch B is not combined;

2) and 2, gear: the clutch A is combined on the left, and the clutch B is not combined;

3) and 3, gear shifting: the clutch A is positioned in the middle position, and the clutch B is combined on the left side;

4) n is kept: clutch a is in the neutral position and clutch B is not engaged.

Specifically, the transmission system comprises a gear shifting motor, the gear shifting motor is connected with a gear shifting drum and a gear shifting executing mechanism and drives the gear shifting drum to rotate through the gear shifting executing mechanism, 2 sections of grooves are formed in the surface of the gear shifting drum to respectively correspondingly control a clutch A and a clutch B, the grooves drive a shifting fork guide pin to realize gear conversion, the gear shifting drum has a gear interlocking function, and only one of the clutch A and the clutch B is in gear at the same time;

the corresponding gear conversion process of the transmission system comprises the following steps:

when the vehicle starts, the clutch A is combined to the right, and the gear 1 is engaged from the gear N to realize the vehicle start;

when the 1 gear is shifted and the 2 gear is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a second-gear driving gear is synchronous with the meshing sleeve of the clutch A, the gear shifting drum continues to rotate to control the clutch A to be combined on the left, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from the first gear to the second gear;

when the gear 2 is shifted and the gear 3 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a three-gear driving gear and a clutch B meshing sleeve are synchronous, the gear shifting drum continues to rotate to control the clutch B to be combined, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 2-gear to 3-gear;

the downshift mode proceeds in reverse of the above process.

In the second embodiment, the motor, the transmission, the main speed reducer and the differential are integrated, a power chain of a traditional automobile is replaced, links such as a clutch, a transmission shaft and a universal joint are omitted, and the transmission efficiency is optimized; meanwhile, 3 gears are set according to the requirements of the adaptive vehicle type, the use requirements are met by the high-speed motor and the combination of different speed ratios of the 3 gears, and the overall cost is low; the transmission gear pair and the main reduction gear pair are driven by cylindrical gears, and the system efficiency is high.

Referring to fig. 3, a multi-speed electric drive transmission system according to a third embodiment of the present invention includes: electric machine EM 6;

the output shaft of the motor EM6 is connected with the input driving gear 13 through the shaft I;

the shaft II is fixedly provided with a secondary driving gear 11 and an input driven gear 14, wherein the input driven gear 14 is correspondingly meshed with the input driving gear 13;

the shaft III is a hollow shaft, a secondary driven gear 9, a secondary driving gear 19 and a first-gear driving gear 15 are sequentially sleeved on the shaft III from left to right, and the secondary driven gear 9 is correspondingly meshed with a secondary driving gear 11;

the IV shaft 26 is fixedly provided with a third-gear driven gear 18, a second-gear driven gear 20, a first-gear driven gear 16 and an output driving gear 23 from left to right, wherein the third-gear driven gear 18 is correspondingly meshed with the second-stage driven gear 9, the second-gear driven gear 20 is correspondingly meshed with the second-gear driving gear 19, and the first-gear driven gear 16 is correspondingly meshed with the first-gear driving gear 15;

the differential mechanism comprises a differential mechanism shell 3, an output driven gear 24 which is correspondingly meshed with an output driving gear 23 is arranged on the differential mechanism shell 3, a left half shaft 25 of the differential mechanism is concentric with a shaft III and penetrates through the inside of the shaft III to output power to a left wheel of a vehicle, a right half shaft 1 of the differential mechanism outputs power to a right wheel of the vehicle, the left half shaft 25 and the right half shaft 1 are respectively connected with a half shaft gear inside the differential mechanism, and the half shaft gear is meshed with a differential mechanism planetary gear;

the clutch A7 is sleeved on the shaft III 8 and is positioned between the first-gear driving gear 15 and the second-gear driving gear 19; the clutch A7 comprises a third-gear hub 71 and a third-gear engaging sleeve 72;

a clutch B5 disposed on the iv shaft 26 between the third driven gear 18 and the second driven gear 20; the clutch B5 comprises a first-gear hub 51 and a first-gear engaging sleeve 52;

the gear shifting drum and the gear shifting actuating mechanism are respectively connected with the clutch A7 and the clutch B5;

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 arranged concentrically with the shaft III.

In particular, the transmission system is capable of achieving the following gears (as shown in table 3):

TABLE 3 Clutch actuation Table for each gear in the third embodiment of the present invention

Note: and V is the corresponding working position of the corresponding clutch under each gear.

1) 1, gear 1: the clutch A is combined on the right, and the clutch B is not combined;

2) and 2, gear: the clutch A is combined on the left, and the clutch B is not combined;

3) and 3, gear shifting: the clutch A is positioned in the middle position, and the clutch B is combined on the left side;

4) n is kept: clutch a is in the neutral position and clutch B is not engaged.

Specifically, the transmission system comprises a gear shifting motor, the gear shifting motor is connected with a gear shifting drum and a gear shifting executing mechanism and drives the gear shifting drum to rotate through the gear shifting executing mechanism, 2 sections of grooves are formed in the surface of the gear shifting drum to respectively correspondingly control a clutch A and a clutch B, the grooves drive a shifting fork guide pin to realize gear conversion, the gear shifting drum has a gear interlocking function, and only one of the clutch A and the clutch B is in gear at the same time;

the corresponding gear conversion process of the transmission system comprises the following steps:

when the vehicle starts, the clutch A is combined to the right, and the gear 1 is engaged from the gear N to realize the vehicle start;

when the 1 gear is shifted and the 2 gear is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a second-gear driving gear is synchronous with the meshing sleeve of the clutch A, the gear shifting drum continues to rotate to control the clutch A to be combined on the left, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from the first gear to the second gear;

when the gear 2 is shifted and the gear 3 is shifted, the motor EM reduces the torque, and the shifting motor drives the shifting drum to rotate to control the clutch A to return to the middle position; then the motor EM adjusts the speed until a three-gear driving gear and a clutch B meshing sleeve are synchronous, the gear shifting drum continues to rotate to control the clutch B to be combined on the left, and after gear combination is completed, the torque of the motor EM is recovered to complete gear switching from 2-gear to 3-gear;

the downshift mode proceeds in reverse of the above process.

In the third embodiment, the clutch a is located on the shaft iii, and compared with a scheme that the clutch a is located on the shaft iv, the synchronous inertia is smaller when the first gear and the second gear are shifted, the motor synchronization time is shorter, and the relative shift speed is faster.

As shown in fig. 5, the present invention further provides a four-wheel drive vehicle using the multi-gear electric drive transmission system, wherein a left half shaft 25 of the multi-gear electric drive transmission system is correspondingly engaged with a front axle differential input gear fixedly connected to a differential case of a front drive axle FR of the four-wheel drive vehicle, and a right half shaft 1 of the multi-gear electric drive transmission system is correspondingly engaged with a rear axle differential input gear fixedly connected to a differential case of a rear drive axle BA of the four-wheel drive vehicle, so as to implement a four-wheel drive running mode of the vehicle.

Fig. 5 is a diagram illustrating only the transmission system according to the second embodiment (fig. 2) as applied to a four-wheel drive vehicle, and similarly, the transmission system according to the first embodiment (fig. 1) or the third embodiment (fig. 3) may also be applied to a four-wheel drive vehicle.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.