Power coupling type dual-motor power gear shifting electric drive axle and engineering machinery

Abstract

The invention discloses a power coupling type dual-motor power gear shifting electric drive axle and engineering machinery, and belongs to the technical field of engineering vehicle electric drive transmission. The power coupling type dual-motor power gear shifting electric drive axle comprises a first motor, a second motor and a driving mechanism. The driving mechanism is used for respectively providing a plurality of gears when different motors work independently and providing a plurality of driving modes when the double motors work simultaneously; the control module is also used for switching working modes according to the size of the load and controlling the distribution proportion of the output torque of each motor according to a preset torque distribution coefficient, including: controlling a low-power motor to independently drive in a low load, controlling a high-power motor to independently drive in a medium load, and controlling double motors to simultaneously drive in a high load; according to the electric drive axle, the gears and the synchronizers are reasonably arranged, so that the electric drive axle is compact in arrangement and rich in working mode; the electric drive axle adopts the dead axle gear as a transmission mechanism, adopts the synchronizer as a gear shifting mechanism, and is simple in structure, good in machining process, reliable in work and low in production cost.

Description

Technical Field

[0001] The present invention relates to a power-coupled dual-motor power-shift electric drive bridge and engineering machinery, belonging to the technical field of electric drive transmission for engineering vehicles. Background Art

[0002] Traditional construction vehicles have limited potential for improving fuel efficiency, and the development of electric construction vehicles is considered a solution to promote healthy industrial economic development. The advancement and development of electric drive axle technology is mutually reinforcing with electric construction vehicles. As the electric construction vehicle industry grows, electric drive systems will also achieve product and technological advancements, and technological advances in electric drive axles will in turn feed into the growth of electric construction vehicles. Electric drive axles primarily include single-motor and dual-motor drive types, with the latter involving both torque coupling and speed coupling. The configuration and control strategy of the electric drive axle directly impact the driving capability and economic efficiency of the electric vehicle. To address the wide torque range and variable operating conditions of construction machinery drive axles, as well as the high energy consumption of existing vehicles, a power-coupled dual-motor powershift drive axle has been proposed.

[0003] Improving the power and economy of electric construction vehicles involves research on drive system configuration design, parameter matching and optimization, and energy management. Furthermore, the energy-saving and emission-reduction potential of construction vehicles depends on the mechanical connection between components and the instantaneous power distribution between power sources—in other words, configuration and energy management. Configuration not only affects the power of construction vehicles but, as the foundation of energy management, also determines algorithm selection and optimization potential. Electric construction vehicles typically require multiple gears to cover the speed and torque range, resulting in power interruptions during shifting, impacting both power and the driving experience.

[0004] Existing electric drive axle reduction structures for construction machinery include multiplanetary systems and mechanical shifting. To meet the high speed requirements of construction machinery, the drive axle has a large speed ratio, but few gears. This results in excess or insufficient power in complex operating conditions, poor adaptability, and high operating costs. Mechanical shifting, in particular, interrupts power during the shift process, affecting performance and driving experience. Existing multiplanetary electric drive axles are complex and expensive to manufacture. Furthermore, the limited number of gears makes torque adaptation impossible in the variable operating conditions of heavy-load, high-torque construction machinery, resulting in high energy consumption and high operating costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a power-coupled dual-motor power-shift electric drive axle and engineering machinery.

[0006] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions.

[0007] In a first aspect, the present invention discloses a power-coupled dual-motor power-shift electric drive axle, comprising: a first motor and a second motor of two different powers, and a drive mechanism connected to the first motor and the second motor respectively; The drive mechanism is used to provide multiple gears when the first motor works alone and the second motor works alone, and to provide multiple drive modes when the first motor and the second motor work simultaneously; The driving mechanism is also used to switch the working mode according to the size of the load, and control the distribution ratio of the output torque of each motor according to a preset torque distribution coefficient, including: controlling the small-power motor of the first motor and the second motor to drive alone when the load is low, controlling the high-power motor of the first motor and the second motor to drive alone when the load is medium, and controlling the first motor and the second motor to drive simultaneously when the load is high; the torque distribution coefficient is used to make the working points of the two motors fall within the high-efficiency range under different working modes.

[0008] Furthermore, the drive mechanism includes: a first gear, a second gear, a third gear, a fourth gear, a fifth gear, a sixth gear, a seventh gear, an eighth gear, a ninth gear, a tenth gear, an eleventh gear, a twelfth gear, a first synchronizer, a second synchronizer, a third synchronizer, a fourth synchronizer, a first motor input shaft, a second motor input shaft, an intermediate shaft, a first output shaft, a differential, a second output half shaft, and a third output half shaft; The first motor is connected to the first synchronizer via the first motor input shaft; the second motor is connected to the second synchronizer and the third synchronizer via the second motor input shaft; the fourth synchronizer is connected to the first output shaft; The connection relationship between the first synchronizer and the first gear and the third gear includes meshing and disengaging; the connection relationship between the second synchronizer and the fifth gear includes meshing and disengaging; the connection relationship between the third synchronizer and the seventh gear and the ninth gear includes meshing and disengaging; the connection relationship between the fourth synchronizer and the sixth gear includes meshing and disengaging; The first gear and the third gear are loosely mounted on the first motor input shaft; the fifth gear, the seventh gear, and the ninth gear are loosely mounted on the second motor input shaft; the second gear, the fourth gear, and the sixth gear are fixedly connected to the intermediate shaft; and the eighth gear and the tenth gear are fixedly connected to the first output shaft. The eleventh gear is fixedly connected to the first output shaft; the eleventh gear is connected to the twelfth gear; the twelfth gear is connected to the differential; the second output half shaft is connected to the differential; and the third output half shaft is connected to the differential.

[0009] Furthermore, the first motor includes four gears when working alone, specifically: In the first gear, the first synchronizer is engaged with the first gear, and the fourth synchronizer is engaged with the sixth gear; In the second gear, the first synchronizer is engaged with the third gear, and the fourth synchronizer is engaged with the sixth gear; In the third gear, the third synchronizer is engaged with the seventh gear, and the second synchronizer is engaged with the fifth gear; In the fourth gear, the third synchronizer is engaged with the ninth gear, and the second synchronizer is engaged with the fifth gear.

[0010] Furthermore, when the first motor operates alone, the relationship between the wheel output torque and the vehicle speed satisfies: ; Where, u is the vehicle speed; n 1 is the motor output speed; i 0 is the main reduction ratio; i 1-i For the first motor i gear ratio; r is the tire rolling radius; T 1 is the output torque of the first motor; T Output torque to the wheels; η 1i When the first motor is working i The transmission efficiency of the gear.

[0011] Furthermore, the second motor has three gears when working alone, specifically: In the first gear, the third synchronizer is engaged with the seventh gear; In the second gear, the third synchronizer is engaged with the ninth gear; In the third gear, the second synchronizer is engaged with the fifth gear, and the fourth synchronizer is engaged with the sixth gear.

[0012] Furthermore, when the second motor operates alone, the relationship between the wheel output torque and the vehicle speed satisfies: ; Where, u is the vehicle speed; T Output torque to the wheels; n 2 is the motor output speed; i 0 is the main reduction ratio; i 2-j For the second motor j gear ratio; r is the tire rolling radius; T 2 is the output torque of the second motor; η 2jWhen the second motor is working j The transmission efficiency of the gear.

[0013] Furthermore, when the first motor and the second motor operate simultaneously, six driving modes are included; Drive mode 1: the first synchronizer is engaged with the first gear, the third synchronizer is engaged with the seventh gear, and the second synchronizer is engaged with the fifth gear; Drive mode 2: the first synchronizer is engaged with the first gear, the third synchronizer is engaged with the ninth gear, and the second synchronizer is engaged with the fifth gear; Driving mode three, the first synchronizer is engaged with the first gear, and the fourth synchronizer is engaged with the sixth gear; Drive mode four: the first synchronizer is engaged with the third gear, the fourth synchronizer is engaged with the sixth gear, and the second synchronizer is engaged with the fifth gear; Drive mode five: the first synchronizer is engaged with the third gear, the third synchronizer is engaged with the ninth gear, and the fourth synchronizer is engaged with the sixth gear; In driving mode six, the first synchronizer is engaged with the first gear, the third synchronizer is engaged with the ninth gear, and the second synchronizer is engaged with the fifth gear.

[0014] Furthermore, when the first motor and the second motor operate simultaneously, the relationship between the wheel output torque and the vehicle speed satisfies: ; Where, u is the vehicle speed; T Output torque to the wheels; n 1 is the motor output speed; n 2 is the motor output speed; i 0 is the main reduction ratio; i 1-i For the first motor i gear ratio; i 2-j For the second motor j gear ratio; r is the tire rolling radius; T 1 is the output torque of the first motor; T 2 is the output torque of the second motor; η 2j When the second motor is working j The transmission efficiency of the gear.

[0015] Furthermore, the torque distribution coefficient controls the distribution ratio of the output torque of each motor, including: With the goal of maximizing the overall efficiency of the electric drive axle, the instantaneous optimal principle is adopted to obtain the optimal working mode and torque distribution coefficient. k T , through the torque distribution coefficient k T The distribution ratio of the output torque of the first motor and the second motor is adjusted so that the operating points of the two motors fall within the high efficiency range.

[0016] In a second aspect, the present invention further discloses an engineering machine, comprising the power-coupled dual-motor power-shift electric drive axle described in the first aspect.

[0017] The beneficial effects achieved by the present invention are: 1) Through the rational arrangement of gears and synchronizers, the electric drive axle is compact and has a variety of working modes; 2) The electric drive axle uses a fixed-axis gear as the transmission mechanism and a synchronizer as the shift mechanism, which has a simple structure, good processing technology, reliable operation and low production cost; 3) A wide range of operating modes can cover both high-speed, low-torque and low-speed, high-torque operating conditions of engineering vehicles; 4) The working mode can be switched freely according to the load. Under low load, the small power motor is driven alone; under medium load, the high power motor is driven alone; under high load, both motors are driven simultaneously. Under the premise of ensuring dynamic performance, it can achieve optimal energy utilization and efficient driving; 5) During the gear shifting process of one motor, the other motor can transmit power normally, and there is no power interruption when all gears are switched, that is, power shifting of all gears can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of a power-coupled dual-motor multi-speed electric drive axle with power shifting function; Figure 2 This is a schematic diagram of the first gear power transmission path of the motor EM1; Figure 3 Schematic diagram of the second gear power transmission path of the motor EM1; Figure 4 Schematic diagram of the third-gear power transmission path of the motor EM1; Figure 5 Schematic diagram of the fourth-gear power transmission path of the motor EM1; Figure 6 This is a schematic diagram of the first gear power transmission path of the motor EM2; Figure 7 Schematic diagram of the second gear power transmission path of the motor EM2; Figure 8 Schematic diagram of the third-gear power transmission path of the motor EM2; Figure 9This is the speed-torque curve when motor EM1 is working; Figure 10 This is the speed-torque curve when motor EM2 is working; Figure 11 is the vehicle speed-torque curve of dual-motor coupling mode; Figure 12 It is the power distribution range of different modes.

[0019] In the figure: 1-first motor, 2-first motor input shaft, 3-first gear, 4-first synchronizer, 5-third gear, 6-second synchronizer, 7-fifth gear, 8-second motor input shaft, 9-seventh gear, 10-third synchronizer, 11-ninth gear, 12-second motor, 13-intermediate shaft, 14-second gear, 15-fourth gear, 16-sixth gear, 17-fourth synchronizer, 18-eighth gear, 19-tenth gear, 20-first output shaft, 21-eleventh gear, 22-twelfth gear, 23-differential, 24-second output axle shaft, 25-third output axle shaft. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are 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 therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0023] Example 1: This example introduces a power-coupled dual-motor power-shift electric drive axle, comprising: a first motor 1 (motor EM1) and a second motor 12 (motor EM2) of two different powers, and a drive mechanism connected to the first motor 1 and the second motor 12 respectively; The drive mechanism is used to provide multiple gears when the first motor 1 works alone and the second motor 12 works alone, and to provide multiple drive modes when the first motor 1 and the second motor 12 work simultaneously; The driving mechanism is also used to switch the working mode according to the size of the load, and control the distribution ratio of the output torque of each motor according to a preset torque distribution coefficient, including: controlling the small-power motor of the first motor 1 and the second motor 12 to be driven alone when the load is low, controlling the high-power motor of the first motor 1 and the second motor 12 to be driven alone when the load is medium, and controlling the first motor 1 and the second motor 12 to be driven simultaneously when the load is high; the torque distribution coefficient is used to make the working points of the two motors fall within the high efficiency range under different working modes.

[0024] like Figure 1 As shown, the drive mechanism includes: a first gear 3, a second gear 14, a third gear 5, a fourth gear 15, a fifth gear 7, a sixth gear 16, a seventh gear 9, an eighth gear 18, a ninth gear 11, a tenth gear 19, an eleventh gear 21, a twelfth gear 22, a first synchronizer 4, a second synchronizer 6, a third synchronizer 10, a fourth synchronizer 17, a first motor input shaft 2, a second motor input shaft 8, an intermediate shaft 13, a first output shaft 20, a differential 23, a second output half shaft 24, and a third output half shaft 25; The motor EM11 is connected to the first synchronizer 4 via the first motor input shaft 2; the motor EM212 is connected to the second synchronizer 6 and the third synchronizer 10 via the second motor input shaft 8; the fourth synchronizer 17 is connected to the first output shaft 20; The connection relationship between the first synchronizer 4 and the first gear 3 and the third gear 5 includes meshing and disengaging; the connection relationship between the second synchronizer 6 and the fifth gear 7 includes meshing and disengaging; the connection relationship between the third synchronizer 10 and the seventh gear 9 and the ninth gear 11 includes meshing and disengaging; the connection relationship between the fourth synchronizer 17 and the sixth gear 16 includes meshing and disengaging; The first gear 3 and the third gear 5 are loosely mounted on the first motor input shaft 2; the fifth gear 7, the seventh gear 9, and the ninth gear 11 are loosely mounted on the second motor input shaft 8; the second gear 14, the fourth gear 15, and the sixth gear 16 are fixedly connected to the intermediate shaft 13; the eighth gear 18 and the tenth gear 19 are fixedly connected to the first output shaft 20; The eleventh gear 21 is fixedly connected to the first output shaft 20; the eleventh gear 21 is connected to the twelfth gear 22; the twelfth gear 22 is connected to the differential 23; the second output half shaft 24 is connected to the differential 23; and the third output half shaft 25 is connected to the differential 23.

[0025] The rational arrangement of gears and synchronizers makes the electric drive axle compact and has a variety of working modes. It uses ten gears and four synchronizers. When the motor EM1 (the first motor) works alone, it provides four gears. When the motor EM2 (the second motor) works alone, it provides three gears. When the motor EM1 and the motor EM2 work together, they provide six working modes. The dual-motor coupling drive system configuration designed in the present invention includes 4 gears when motor EM1 works alone, 3 gears when motor EM2 works alone, and 6 working modes formed by motor EM1 and motor EM2 working simultaneously; the synchronizer engagement status of each mode is shown in Table 1, Table 2, and Table 3. In the table: A represents the left position of the first synchronizer, B represents the right position of the first synchronizer, C represents the left position of the third synchronizer, D represents the right position of the third synchronizer, E represents the right position of the second synchronizer, and F represents the left position of the fourth synchronizer. ● indicates that the left or right side of the synchronizer is in an engaged state, and ○ indicates that the left or right side of the synchronizer is in a disengaged state.

[0026] Table 1 Synchronizer status in each mode when EM1 works alone ; In first gear, the first synchronizer is engaged with the first gear, and the fourth synchronizer is engaged with the sixth gear; In the second gear, the first synchronizer is coupled to the third gear, and the fourth synchronizer is coupled to the sixth gear; In the third gear, the third synchronizer is coupled to the seventh gear, and the second synchronizer is coupled to the fifth gear; In the fourth gear, the third synchronizer is coupled with the ninth gear, and the second synchronizer is coupled with the fifth gear.

[0027] Table 2 Synchronizer status of each mode when EM2 works alone ; The third synchronizer of the first gear is engaged with the seventh gear; The third synchronizer of the second gear is combined with the ninth gear; In the third gear, the second synchronizer is coupled to the fifth gear, and the fourth synchronizer is coupled to the sixth gear.

[0028] Table 3 Synchronizer status in each mode when EM1 and EM2 work simultaneously ; In mode 1, the first synchronizer is coupled to the first gear, the third synchronizer is coupled to the seventh gear, and the second synchronizer is coupled to the fifth gear.

[0029] In mode 2, the first synchronizer is combined with the first gear, the third synchronizer is combined with the ninth gear, and the second synchronizer is combined with the fifth gear.

[0030] In mode three, the first synchronizer is coupled to the first gear, and the fourth synchronizer is coupled to the sixth gear.

[0031] In mode four, the first synchronizer is combined with the third gear, the fourth synchronizer is combined with the sixth gear, and the second synchronizer is combined with the fifth gear.

[0032] In mode five, the first synchronizer is combined with the third gear, the third synchronizer is combined with the ninth gear, and the fourth synchronizer is combined with the sixth gear.

[0033] Mode 6: The first synchronizer is combined with the first gear, the third synchronizer is combined with the ninth gear, and the second synchronizer is combined with the fifth gear.

[0034] The power flow direction is different in different modes. The first gear power transmission path of motor EM1 is as follows: Figure 2 As shown, the power of the motor EM1 passes through the first motor input shaft, the first gear, the second gear, the intermediate shaft, the sixth gear, the fifth gear, the second motor input shaft, the seventh gear, the eighth gear, the first output shaft, the eleventh gear, the twelfth gear, the differential, the second output half shaft, and the third output half shaft in sequence to output the power.

[0035] The second gear power transmission path of motor EM1 is as follows Figure 3As shown, the power of the motor EM1 is output through the first motor input shaft, the first gear, the second gear, the intermediate shaft, the fourth synchronizer, the first output shaft, the eleventh gear, the twelfth gear, the differential, the second output half shaft, and the third output half shaft in sequence.

[0036] The third gear power transmission path of motor EM1 is as follows Figure 4 As shown, the power of the motor EM1 passes through the first motor input shaft, the first gear, the first synchronizer, the third gear, the fourth gear, the sixth gear, the intermediate shaft, the fourth synchronizer, the first output shaft, the eleventh gear, the twelfth gear, the differential, the second output half shaft, and the third output half shaft in sequence to output the power.

[0037] The fourth-gear power transmission path of motor EM1 is as follows: Figure 5 As shown, the power of the motor EM1 passes through the first motor input shaft, the first gear, the second gear, the intermediate shaft, the sixth gear, the fifth gear, the second motor input shaft, the ninth gear, the tenth gear, the first output shaft, the eleventh gear, the twelfth gear, the differential, the second output half shaft, and the third output half shaft in sequence to output the power.

[0038] The power transmission path of the first gear of the motor EM2 is as follows Figure 6 As shown, the power of the motor EM2 is output through the second motor input shaft, the third synchronizer, the seventh gear, the eighth gear, the first output shaft, the eleventh gear, the twelfth gear, the differential, the second output half shaft, and the third output half shaft in sequence.

[0039] The power transmission path of the second gear of the motor EM2 is as follows Figure 7 As shown, the power of the motor EM2 passes through the second motor input shaft, the third synchronizer, the fifth gear, the sixth gear, the fourth synchronizer, the first output shaft, the eleventh gear, the twelfth gear, the differential, the second output half shaft, and the third output half shaft in sequence to output the power.

[0040] The power transmission path of the third gear of the motor EM2 is as follows Figure 8 As shown, the power of the motor EM2 is outputted through the second motor input shaft, the ninth gear, the tenth gear, the first output shaft, the eleventh gear, the twelfth gear, the differential, the second output half shaft, and the third output half shaft in sequence.

[0041] like Figure 9As shown, when the drive system is in the state where the motor EM1 is working, the relationship between the wheel output torque and the vehicle speed satisfies: ; Where, u is the vehicle speed (km / h); n 1 is the motor output speed (r / min); i 0 is the main reduction ratio; i 1-i For the first motor i gear ratio; r is the tire rolling radius; T 1 is the output torque of the first motor (N·m); T is the wheel output torque (N·m); η 1i When the first motor is working i The transmission efficiency of the gear.

[0042] like Figure 10 As shown, the relationship between the driving torque and vehicle speed of the three gears of the motor EM2 when it is working satisfies: ; Where, u is the vehicle speed (km / h); T is the wheel output torque (N·m); n 2 is the motor output speed (r / min); i 0 is the main reduction ratio; i 2-j For the second motor j gear ratio; r is the tire rolling radius; T 2 is the output torque of the second motor (N·m); η 2j When the second motor is working j The transmission efficiency of the gear.

[0043] like Figure 11 As shown in Figure 2, when the drive system is in dual-motor working mode, the relationship between the wheel output torque and vehicle speed of the engineering vehicle in the six driving modes satisfies: ; In order to make engineering vehicles more economical when driving under typical working conditions and to improve their endurance, it is necessary to distribute the motor's operating points as much as possible in high-efficiency areas. kT is defined as the torque distribution coefficient when the dual-motor coupled drive system is operating. The torque distribution coefficient kT is used to adjust the distribution ratio of the output torque of motor EM1 and motor EM2 so that the operating points of the two motors fall within the high-efficiency range. When dividing the modes, the situation when a motor works alone is not divided into a separate mode, but is regarded as a special case of the dual-motor coupled drive mode. The torque distribution coefficient kT when motor EM1 works alone is defined as 1, and the torque distribution coefficient kT when motor EM2 works alone is defined as 0.

[0044] With the goal of minimizing instantaneous power loss, the energy loss calculation formula is used to calculate the power loss for each mode at different vehicle speeds and required torques. The basis for dividing the modes into different speed and torque ranges is: ; According to the above formula, the mode distribution within the maximum driving torque range of the engineering vehicle is obtained by the instantaneous optimal torque distribution strategy, as follows: Figure 12 shown.

[0045] Example 2 is based on the same inventive concept as Example 1. This example introduces an engineering machine, including the power-coupled dual-motor power-shift electric drive axle described in the first aspect.

[0046] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A power-coupled dual-motor power-shift electric drive axle, characterized in that: include: A first motor (1) and a second motor (12) of two different powers, and a drive mechanism connected to the first motor (1) and the second motor (12) respectively; The driving mechanism is used to provide multiple gears when the first motor (1) works alone and when the second motor (12) works alone, and to provide multiple driving modes when the first motor (1) and the second motor (12) work simultaneously; The driving mechanism is further used to switch the working mode according to the size of the load and control the distribution ratio of the output torque of each motor according to a preset torque distribution coefficient, including: controlling the low-power motor of the first motor (1) and the second motor (12) to be driven alone when the load is low, controlling the high-power motor of the first motor (1) and the second motor (12) to be driven alone when the load is medium, and controlling the first motor (1) and the second motor (12) to be driven simultaneously when the load is high; the torque distribution coefficient is used to make the working points of the two motors fall into the high-efficiency range under different working modes.

2. The power-coupled dual-motor power-shift electric drive axle according to claim 1, characterized in that: The driving mechanism comprises: a first gear (3), a second gear (14), a third gear (5), a fourth gear (15), a fifth gear (7), a sixth gear (16), a seventh gear (9), an eighth gear (18), a ninth gear (11), a tenth gear (19), an eleventh gear (21), a twelfth gear (22), a first synchronizer (4), a second synchronizer (6), a third synchronizer (10), a fourth synchronizer (17), a first motor input shaft (2), a second motor input shaft (8), an intermediate shaft (13), a first output shaft (20), a differential (23), a second output half shaft (24), and a third output half shaft (25); The first motor (1) is connected to the first synchronizer (4) via the first motor input shaft (2); the second motor (12) is connected to the second synchronizer (6) and the third synchronizer (10) via the second motor input shaft (8); the fourth synchronizer (17) is connected to the first output shaft (20); The connection relationship between the first synchronizer (4) and the first gear (3) and the third gear (5) includes meshing and disengaging; the connection relationship between the second synchronizer (6) and the fifth gear (7) includes meshing and disengaging; the connection relationship between the third synchronizer (10) and the seventh gear (9) and the ninth gear (11) includes meshing and disengaging; the connection relationship between the fourth synchronizer (17) and the sixth gear (16) includes meshing and disengaging; The first gear (3) and the third gear (5) are loosely mounted on the first motor input shaft (2); the fifth gear (7), the seventh gear (9), and the ninth gear (11) are loosely mounted on the second motor input shaft (8); the second gear (14), the fourth gear (15), and the sixth gear (16) are fixedly connected to the intermediate shaft (13); and the eighth gear (18) and the tenth gear (19) are fixedly connected to the first output shaft (20); The eleventh gear (21) is fixedly connected to the first output shaft (20); the eleventh gear (21) is connected to the twelfth gear (22); the twelfth gear (22) is connected to the differential (23); the second output half shaft (24) is connected to the differential (23); and the third output half shaft (25) is connected to the differential (23).

3. The power-coupled dual-motor power-shift electric drive axle according to claim 2, characterized in that: The first motor (1) includes four gears when working alone, specifically: In the first gear, the first synchronizer (4) is engaged with the first gear (3), and the fourth synchronizer (17) is engaged with the sixth gear (16); In the second gear, the first synchronizer (4) is engaged with the third gear (5), and the fourth synchronizer (17) is engaged with the sixth gear (16); In the third gear, the third synchronizer (10) is meshed with the seventh gear (9), and the second synchronizer (6) is meshed with the fifth gear (7); In the fourth gear, the third synchronizer (10) is engaged with the ninth gear (11), and the second synchronizer (6) is engaged with the fifth gear (7).

4. The power-coupled dual-motor power-shift electric drive axle according to claim 3, characterized in that: When the first motor (1) works alone, the relationship between the wheel output torque and the vehicle speed satisfies: ； Where, u is the vehicle speed; n 1 is the motor output speed; i 0 is the main reduction ratio; i 1-i For the first motor i gear ratio; r is the tire rolling radius; T 1 is the output torque of the first motor; T Output torque to the wheels; η 1i When the first motor is working i The transmission efficiency of the gear.

5. The power-coupled dual-motor power-shift electric drive axle according to claim 2, characterized in that: The second motor (12) includes three gears when working alone, specifically: In the first gear, the third synchronizer (10) is engaged with the seventh gear (9); In the second gear, the third synchronizer (10) is meshed with the ninth gear (11); In the third gear, the second synchronizer (6) is engaged with the fifth gear (7), and the fourth synchronizer (17) is engaged with the sixth gear (16).

6. The power-coupled dual-motor power-shift electric drive axle according to claim 5, characterized in that: When the second motor (12) operates alone, the relationship between the wheel output torque and the vehicle speed satisfies: ； Where, u is the vehicle speed; T Output torque to the wheels; n 2 is the motor output speed; i 0 is the main reduction ratio; i 2-j For the second motor j gear ratio; r is the tire rolling radius; T 2 is the output torque of the second motor; η 2j When the second motor is working j The transmission efficiency of the gear.

7. The power-coupled dual-motor power-shift electric drive axle according to claim 2, characterized in that: Six driving modes are included when the first motor (1) and the second motor (12) operate simultaneously; Driving mode 1, the first synchronizer (4) is engaged with the first gear (3), the third synchronizer (10) is engaged with the seventh gear (9), and the second synchronizer (6) is engaged with the fifth gear (7); Driving mode 2, the first synchronizer (4) is meshed with the first gear (3), the third synchronizer (10) is meshed with the ninth gear (11), and the second synchronizer (6) is meshed with the fifth gear (7); Driving mode three, the first synchronizer (4) is meshed with the first gear (3), and the fourth synchronizer (17) is meshed with the sixth gear (16); Drive mode four, the first synchronizer (4) is engaged with the third gear (5), the fourth synchronizer (17) is engaged with the sixth gear (16), and the second synchronizer (6) is engaged with the fifth gear (7); Driving mode five, the first synchronizer (4) is engaged with the third gear (5), the third synchronizer (10) is engaged with the ninth gear (11), and the fourth synchronizer (17) is engaged with the sixth gear (16); In driving mode six, the first synchronizer (4) is engaged with the first gear (3), the third synchronizer (10) is engaged with the ninth gear (11), and the second synchronizer (6) is engaged with the fifth gear (7).

8. The power-coupled dual-motor power-shift electric drive axle according to claim 7, characterized in that: When the first motor (1) and the second motor (12) operate simultaneously, the relationship between the wheel output torque and the vehicle speed satisfies: ； Where, u is the vehicle speed; T Output torque to the wheels; n 1 is the motor output speed; n 2 is the motor output speed; i 0 is the main reduction ratio; i 1-i For the first motor i gear ratio; i 2-j For the first and second motors j gear ratio; r is the tire rolling radius; T 1 is the output torque of the first motor; T 2 is the output torque of the second motor; η 2j When the second motor is working j The transmission efficiency of the gear.

9. The power-coupled dual-motor power-shift electric drive axle according to claim 1, characterized in that: The torque distribution coefficient controls the distribution ratio of the output torque of each motor, including: With the goal of maximizing the overall efficiency of the electric drive axle, the instantaneous optimal principle is adopted to obtain the optimal working mode and torque distribution coefficient. k T , through the torque distribution coefficient k T The distribution ratio of the output torque of the first motor and the second motor is adjusted so that the operating points of the two motors fall within the high efficiency range.

10. An engineering machine, characterized in that: It includes the power-coupled dual-motor power-shift electric drive axle described in any one of claims 1-9.

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