A series-parallel hybrid tractor mechanical coupling device and its control method

Abstract

A series-parallel hybrid tractor mechanical coupling device and its control method. Since the ring gear on the first planetary gear set is in external meshing transmission with the ring gear on the second planetary gear set, the structure of the present invention is more compact and has a greater load-bearing capacity. At the same time, the present invention uses an engine, an ISG motor, and a PTO motor as the power sources of the tractor. The engine and the ISG motor transmit power to the variable speed drive axle, and the PTO motor independently drives power to the rotary tillage mechanism. By controlling the double-row planetary gear coupling mechanism, the power of the engine, the ISG motor, and the PTO motor can be converged to the variable speed drive axle, which can simplify the structure of the transmission and is beneficial to the overall vehicle layout. According to different operation requirements, the appropriate working mode can be selected, thereby improving the working efficiency and energy utilization rate of the engine. Due to the introduction of the motor, the working area of the engine can be optimized, the energy utilization efficiency can be improved, and environmental pollution can be reduced, etc.

Description

Technical Field

[0001] The present invention relates to the field of tractors, and particularly to a mechanical coupling device and a control method for a series-parallel hybrid tractor. Background Art

[0002] In order to solve problems such as improving fuel economy and reducing pollutant gas emissions, the innovative improvement and upgrade of traditional fuel vehicles to be designed as power sources using hybrid power of fuel and electricity has become an important development direction and future trend in the industry.

[0003] In the research of tractors, most tractors still use diesel engines as power sources. Such traditional diesel tractors not only have high noise, low efficiency but also seriously pollute the environment, resulting in serious energy waste and exhaust emissions; pure electric tractors, due to the main power source being an electric motor, will have the hidden danger of insufficient power when facing complex operating conditions, and the charging time problem is also a major problem to be solved; although the use of hybrid power for driving has been disclosed in the prior art, there are generally problems such as too large a volume of the coupling mechanism, too single an operating mode, and low energy utilization rate.

[0004] Therefore, it is particularly important to provide a mechanical coupling device and a control method for a series-parallel hybrid tractor. Summary of the Invention

[0005] To overcome the deficiencies in the background art, the present invention provides a mechanical coupling device and a control method for a series-parallel hybrid tractor. The present invention realizes a series-parallel hybrid tractor with high fuel economy, low pollutant gas emissions, and capable of adjusting power output according to the working environment, improves the power performance and economy of the tractor, and significantly reduces the volume of the coupling mechanism, etc.

[0006] To achieve the above-mentioned invention purpose, the present invention adopts the following technical solutions:

[0007] A series-parallel hybrid tractor mechanical coupling device, comprising a vehicle controller, an engine controller, a fuel tank, an engine, an ISG motor, a clutch, a double-row planetary gear coupling mechanism, a transmission, a drive axle, a rotary tillage mechanism, an ISG motor controller, a coupler controller, a PTO motor, a distribution box, a PTO motor controller, a battery pack, a BMS controller and a battery charger. The distribution box is respectively connected to the vehicle controller, the engine controller, the ISG motor controller, the coupler controller, the PTO motor controller and the battery pack. The engine controller and the ISG motor controller are connected in parallel. The engine controller is connected to the engine, and the engine is respectively connected to the fuel tank and the ISG motor. The ISG motor is connected to the ISG motor controller, and the ISG motor is connected to the clutch. The clutch is connected to the first input shaft in the double-row planetary gear coupling mechanism. The first output shaft in the double-row planetary gear coupling mechanism is connected to the transmission, and the transmission is connected to the drive axle of the tractor. The second input shaft in the double-row planetary gear coupling mechanism is connected to the PTO motor, and the PTO motor is connected to the PTO motor controller. The third output shaft in the double-row planetary gear coupling mechanism is connected to the rotary tillage mechanism. The battery pack is connected to the BMS controller, and the BMS controller is connected to the battery charger. The coupler controller is respectively connected to a synchronizer, a metal belt continuously variable transmission mechanism, a first electromagnetic lock, a second electromagnetic lock and a third electromagnetic lock in the double-row planetary gear coupling mechanism to form the series-parallel hybrid tractor mechanical coupling device.

[0008] The series-parallel hybrid tractor mechanical coupling device described above. The double-row planetary gear coupling mechanism includes a first input shaft, a first electromagnetic lock, a first planetary gear set, a second electromagnetic lock, a first output shaft, a synchronizer, a third output shaft, a metal belt continuously variable transmission mechanism, a second output shaft, a third electromagnetic lock, a second planetary gear set, and a second input shaft. The first sun gear in the first planetary gear set is arranged at the right end of the first input shaft. A first electromagnetic lock is provided on the outer edge surface of the first input shaft on the left side of the first planetary gear set. A second electromagnetic lock is provided around the first planetary gear set. The first planet carrier in the first planetary gear set is connected to the left end of the first output shaft. A synchronizer is provided on the outer edge surface of the first output shaft on the right side of the first planet carrier. The driving working wheel in the metal belt continuously variable transmission mechanism is arranged on the first output shaft. The driven working wheel in the metal belt continuously variable transmission mechanism is arranged on the second output shaft. The driving working wheel and the driven working wheel are connected by a metal belt. The fixed part of the driven working wheel is connected to the third output shaft. A third electromagnetic lock for locking or unlocking the transmission of the second sun gear in the second planetary gear set to the second output shaft is provided on the outer edge surface of the second output shaft. The left end of the second output shaft is connected to the second sun gear in the second planetary gear set. The second planet carrier in the second planetary gear set is connected to the second input shaft. The first ring gear in the first planetary gear set and the second ring gear in the adjacent second planetary gear set are in external meshing transmission.

[0009] The series-parallel hybrid tractor mechanical coupling device described above. The first planetary gear set includes a first sun gear, a first ring gear, a first planetary gear, and a first planet carrier. The first planetary gear is in external meshing with the first sun gear, and the first planetary gear is in internal meshing with the first ring gear. The first planetary gear is connected to the first planet carrier and is positioned and supported by the first planet carrier. The first ring gear is connected to the second electromagnetic lock.

[0010] The series-parallel hybrid tractor mechanical coupling device described above. The metal belt continuously variable transmission mechanism includes a driving working wheel arranged on the first output shaft and a driven working wheel arranged on the second output shaft. The driving working wheel and the driven working wheel are connected by a metal belt. The driving working wheel includes a fixed part of the driving working wheel, a movable part of the driving working wheel, and a hydraulic control cylinder of the driving working wheel. The driven working wheel includes a fixed part of the driven working wheel, a movable part of the driven working wheel, and a hydraulic control cylinder of the driven working wheel. The hydraulic control cylinder of the driving working wheel and the hydraulic control cylinder of the driven working wheel respectively push the movable part of the driving working wheel and the movable part of the driven working wheel to work to realize the continuously variable transmission of the metal belt type continuously variable transmission mechanism.

[0011] The mechanical coupling device of the series - parallel hybrid tractor described above, the second planetary gear set includes a second planet carrier, second planet gears, a second ring gear, and a second sun gear. The second planet gears are externally meshed with the second sun gear and internally meshed with the second ring gear. The second planet gears are connected to the second planet carrier and are positioned and supported by the second planet carrier.

[0012] The mechanical coupling device of the series - parallel hybrid tractor described above, the BMS controller controls the battery pack. The battery pack supplies power to the PTO motor, ISG motor, synchronizer, first electromagnetic lock, second electromagnetic lock, and third electromagnetic lock. The coupler controller respectively controls the interruption and engagement of the synchronizer, controls the operation of the hydraulic control cylinders of the driving working wheel and the driven working wheel, and controls the locking or unlocking of the first electromagnetic lock, second electromagnetic lock, and third electromagnetic lock.

[0013] The mechanical coupling device of the series - parallel hybrid tractor described above, the vehicle controller obtains information of the BMS controller, engine controller, ISG motor controller, coupler controller, PTO motor controller, and distribution box through the high - speed CAN bus, and sends control signals to the corresponding controllers and distribution box through the high - speed CAN bus, and obtains the operation information of the tractor through the low - speed CAN bus.

[0014] The mechanical coupling device of the series - parallel hybrid tractor described above, the operation information includes key signal, gearbox gear position signal, pedal position signal, operation mode signal, PTO motor and rotating shaft speed signal.

[0015] The mechanical coupling device of the series - parallel hybrid tractor described above, the ISG motor is connected in series with the engine. The mechanical energy output by the engine is converted into electrical energy in the ISG motor, and then the ISG motor is connected to the drive axle for power drive.

[0016] A control method for the mechanical coupling device of a series - parallel hybrid tractor. After the tractor starts, the vehicle enters the system self - inspection status. After the vehicle is normal and the self - inspection passes, it can run. The vehicle controller obtains the vehicle operation demand signal, and sends control signals to each controller and distribution box according to the obtained signal, so as to select different control operation modes, specifically as follows:

[0017] A. Only walking mode:

[0018] ① PTO motor independently drives the walking mode:

[0019] When the vehicle controller receives a driving signal, if the vehicle speed V is less than the preset value Veb (this preset value is specified as the bottom line of the vehicle speed), when the vehicle speed is lower than this value, the engine cannot operate stably, or is in a state of high fuel consumption and high emissions. The signal collector collects signals and transmits them to the vehicle controller. The vehicle controller issues start and stop (idle) commands to the PTO motor controller and the engine controller respectively. The PTO motor and the engine receive the commands. The PTO motor works alone to provide power, and the engine is in an idle or stopped state. At this time, the vehicle enters the PTO motor independent drive walking mode; the coupler controller controls the first electromagnetic lock to lock, the second electromagnetic lock to disconnect, the third electromagnetic lock to lock, and the synchronizer to interrupt. At this time, the PTO motor is in a working state. The vehicle controller calculates the target speed np of the PTO motor, and then transmits the signal to the PTO motor controller. The PTO motor operates at a constant speed according to the signal of the PTO motor controller. The sensor collects the actual speed of the PTO motor in real time. The vehicle controller compares whether the actual speed of the PTO motor is equal to np and promptly feeds back to the PTO motor controller, so that the PTO motor controller can control the speed of the PTO motor in real time and maintain the constant speed operation of the PTO motor;

[0020] ② Engine-ISG motor series drive walking mode:

[0021] When the vehicle controller receives a driving signal, the vehicle controller calculates the real-time required power Px. When the rated power Pq of the engine-ISG motor is greater than or equal to Px, and the engine can operate in the high-efficiency working range, at this time, the vehicle enters the engine-ISG motor series drive mode. The coupler controller controls the first electromagnetic lock to disengage, the second and third electromagnetic locks to engage, and the synchronizer to interrupt. At this time, the engine and the ISG motor are in a working state. The vehicle controller calculates the target speed nq of the ISG motor, and then transmits the signal to the engine controller and the ISG motor controller. The engine adjusts its speed in real time according to the signal of the engine controller, and the ISG motor adjusts its speed in real time according to the signal of the ISG motor controller;

[0022] ③ Parallel drive walking mode:

[0023] When the vehicle controller receives a driving signal, the vehicle controller calculates the real-time required power Px. When the rated power Pq of the engine-ISG motor is less than Px or the engine cannot operate in the high-efficiency working range, the vehicle enters the parallel driving mode. The coupler controller controls the first electromagnetic lock and the second electromagnetic lock to disconnect, the third electromagnetic lock to engage, and the synchronizer to disengage. At this time, the engine, the ISG motor, and the PTO motor are all in the working state. The vehicle controller calculates the target speed nq of the ISG motor and the target speed np of the PTO motor based on the maximum working efficiency distribution control strategy, and then transmits the signal to the engine controller, the ISG motor controller, and the PTO motor controller. The engine controller, the ISG motor controller, and the PTO motor controller adjust the speed of the control components in real time according to the signal, so that the vehicle reaches the desired working condition;

[0024] B. Only operation mode:

[0025] ① PTO motor independent driving operation mode:

[0026] When the vehicle controller receives an operation signal, the vehicle controller calculates the real-time required power Px. When the rated power Pe of the PTO motor is greater than or equal to Px, the vehicle enters the PTO motor independent driving operation mode. The coupler controller controls the first electromagnetic lock to fix the first sun gear, the second electromagnetic lock to engage, the third electromagnetic lock to disengage, and the synchronizer to disengage. At this time, the PTO motor is in the working state. The vehicle controller calculates the target speed np of the PTO motor, and then transmits the signal to the PTO motor controller. The PTO motor operates at a constant speed according to the signal of the PTO motor controller. The sensor collects the actual speed of the PTO motor in real time. The vehicle controller compares whether the actual speed of the PTO motor is equal to np and promptly feedbacks it to the PTO motor controller, so that the PTO motor controller can control the speed of the PTO motor in real time and maintain the constant speed operation of the PTO motor;

[0027] ② Parallel driving operation mode

[0028] When the vehicle controller receives an operation signal, the vehicle controller calculates the real-time required power Px. When the rated power Pe of the PTO motor is less than Px, the vehicle enters the parallel driving operation mode. The coupler controller controls the first electromagnetic lock to engage, the second electromagnetic lock and the third electromagnetic lock to disengage, and the synchronizer to disengage. At this time, the engine, the ISG motor, and the PTO motor are all in the working state. The vehicle controller calculates the target speed nq of the ISG motor and the target speed np of the PTO motor based on the maximum working efficiency distribution control strategy, and then transmits the signal to the engine controller, the ISG motor controller, and the PTO motor controller. The engine controller, the ISG motor controller, and the PTO motor controller adjust the speed of the control components in real time according to the signal, so that the vehicle reaches the desired working condition;

[0029] C. Traveling and operating separation mode:

[0030] When the vehicle controller enters the traveling and operating separation mode, the vehicle controller calculates the real-time required traveling power Px1 and the real-time required operating power Px2. When the rated power Pq of the engine-ISG motor is greater than or equal to Px1, and the rated power Pe of the PTO motor is greater than or equal to Px2, and the engine can operate in the high-efficiency operating range, at this time, the vehicle controller sends a traveling and operating separation signal to the coupler controller. The coupler controller controls the first electromagnetic lock and the third electromagnetic lock to be interrupted, the second electromagnetic lock to be engaged, and the synchronizer to be interrupted. At this time, the engine, the ISG motor, and the PTO motor are all in the working state. The vehicle controller calculates the target speed nq of the ISG motor and the target speed np of the PTO motor, and then transmits the signal to the engine controller, the ISG motor controller, and the PTO motor controller. The engine adjusts the speed in real time according to the signal of the engine controller. The ISG motor and the PTO motor operate at a constant speed according to the signals of the ISG motor controller and the PTO motor controller. The sensor real-time collects the actual speeds of the ISG motor and the PTO motor. The vehicle controller compares the actual speeds of the ISG motor and the PTO motor with the target speeds of the ISG motor and the PTO motor and transmits the signal to the ISG motor controller and the PTO motor controller in real time, and controls the speeds of the ISG motor and the PTO motor through the ISG motor controller and the PTO motor controller to keep the ISG motor and the PTO motor operating at a constant speed;

[0031] D. Traveling and operating coupling mode:

[0032] When the vehicle controller enters the walking operation coupling mode, the vehicle controller calculates the real-time required walking power Px1 and the real-time required operation power Px2. When the rated power Pq of the engine-ISG motor < Px1 or the rated power Pe of the PTO motor < Px2 and the engine cannot operate in the high-efficiency working range, at this time, the vehicle controller sends a walking operation coupling signal to the coupler controller. The coupler controller controls the first electromagnetic lock, the second electromagnetic lock, and the third electromagnetic lock to disengage, the synchronizer to engage, and the hydraulic control cylinders of the driving working wheel and the driven working wheel in the metal belt continuously variable transmission mechanism to work. At this time, the engine, the ISG motor, and the PTO motor are all in the working state. The vehicle controller calculates the target speed nq of the ISG motor, the target speed np of the PTO motor, and the pressures of the hydraulic control cylinders of the driving working wheel and the driven working wheel based on the maximum working efficiency distribution control strategy and the required speeds of the first input shaft and the third output shaft, and then transmits the signals to the engine controller, the ISG motor controller, the PTO motor controller, and the coupler controller. The engine adjusts the speed in real time according to the signal of the engine controller, the ISG motor and the PTO motor adjust the speed in real time according to the signals of the ISG motor controller and the PTO motor controller, and the hydraulic control cylinders of the driving working wheel and the driven working wheel control the transmission ratio of the metal belt continuously variable transmission mechanism in real time according to the signal of the coupler controller. The sensor collects the actual speeds of the first input shaft and the third output shaft in real time. The vehicle controller compares the actual speeds of the first input shaft and the third output shaft with the required speeds of the first input shaft and the third output shaft, and transmits the signals to the engine controller, the ISG motor controller, the PTO motor controller, and the coupler controller in real time to control the operation of the corresponding components, so as to keep the first input shaft adjusting the speed in real time and the third output shaft operating at a constant speed.

[0033] Adopting the technical solution described above, the present invention has the following advantages:

[0034] In the double-row planetary gear coupling mechanism set in the present invention, since the ring gear on the first planetary gear set is in external meshing transmission with the ring gear on the second planetary gear set, the structure is more compact and the load-bearing capacity is larger. At the same time, the present invention uses the engine, the ISG motor, and the PTO motor as the power sources of the tractor. The engine and the ISG motor transmit the power to the transmission drive axle, and the PTO motor independently drives the power to the rotary tillage mechanism. By controlling the double-row planetary gear coupling mechanism, the powers of the engine, the ISG motor, and the PTO motor can be converged to the transmission drive axle, which can simplify the structure of the gearbox, is beneficial to the overall vehicle layout, and can select a suitable working mode according to different operation requirements, thereby improving the working efficiency and energy utilization rate of the engine. Further, the power sources used in the present invention are the engine, the ISG motor, and the PTO motor. Due to the introduction of the motor, the working area of the engine can be optimized, the energy utilization efficiency can be improved, and environmental pollution can be reduced, etc. It is suitable for wide promotion and application. Brief Description of the Drawings

[0035] Figure 1 is a schematic structural diagram of the present invention;

[0036] Figure 2 is a schematic structural diagram of the double-row planetary gear coupling mechanism in the present invention;

[0037] Figure 3 is a schematic structural diagram of the first planetary gear set in the present invention;

[0038] Figure 4 is a schematic structural diagram of the second planetary gear set in the present invention;

[0039] Figure 5 is a schematic structural diagram of the metal belt continuously variable transmission mechanism in the present invention;

[0040] Figure 6 is a circuit connection diagram of the control system of the mechanical coupling device in the present invention;

[0041] Figure 7 is a flowchart A of the control method of the mechanical coupling device in the present invention;

[0042] Figure 8 is a flowchart B of the control method of the mechanical coupling device in the present invention;

[0043] Figure 9 is a flowchart C of the control method of the mechanical coupling device in the present invention;

[0044] Figure 10 is a flowchart D of the control method of the mechanical coupling device in the present invention;

[0045] In the figure: 1. Vehicle controller; 2. Engine controller; 3. Fuel tank; 4. Engine; 5. ISG motor; 6. Clutch; 7. Double-row planetary gear coupling mechanism; 8. Transmission; 9. Drive axle; 10. Rotary tillage mechanism; 11. ISG motor controller; 12. Coupler controller; 13. PTO motor; 14. Distribution box; 15. PTO motor controller; 16. Battery pack; 17. BMS controller; 18. Battery charger; 19. First input shaft; 20. First electromagnetic lock; 21. First planetary gear set; 21s. First sun gear; 21r. First ring gear; 21p. First planetary gear; 21c. First planetary carrier; 22. Second electromagnetic lock; 23. First output shaft; 24. Synchronizer; 25. Third output shaft; 26. Metal belt continuously variable transmission mechanism; 2601. Fixed part of the driving pulley; 2602. Movable part of the driving pulley; 2603. Hydraulic control cylinder of the driving pulley; 2604. Metal belt; 2605. Fixed part of the driven pulley; 2606. Movable part of the driven pulley; 2607. Hydraulic control cylinder of the driven pulley; 27. Second output shaft; 28. Third electromagnetic lock; 29. Second planetary gear set; 29c. Second planetary carrier; 29p. Second planetary gear; 29r. Second ring gear; 29s. Second sun gear; 30. Second input shaft. Detailed implementation mode

[0046] The present invention can be more specifically explained by the following embodiments, and the present invention is not limited to the following embodiments;

[0047] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "lateral", "length", "width", "height", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "side", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0048] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0049] Combined with the attached Figures 1 to 10The described series-parallel hybrid tractor mechanical coupling device includes a vehicle controller 1, an engine controller 2, a fuel tank 3, an engine 4, an ISG motor 5, a clutch 6, a double-row planetary gear coupling mechanism 7, a transmission 8, a drive axle 9, a rotary tillage mechanism 10, an ISG motor controller 11, a coupler controller 12, a PTO motor 13, a distribution box 14, a PTO motor controller 15, a battery pack 16, a BMS controller 17, and a battery charger 18. The distribution box 14 is respectively connected to the vehicle controller 1, the engine controller 2, the ISG motor controller 11, the coupler controller 12, the PTO motor controller 15, and the battery pack 16. The engine controller 2 and the ISG motor controller 11 are connected in parallel. The engine controller 2 is connected to the engine 4. The engine 4 is respectively connected to the fuel tank 3 and the ISG motor 5. The ISG motor 5 is connected to the ISG motor controller 11. The ISG motor 5 is connected to the clutch 6. The clutch 6 is connected to the first input shaft 19 in the double-row planetary gear coupling mechanism 7. The first output shaft 23 in the double-row planetary gear coupling mechanism 7 is connected to the transmission 8. The transmission 8 is connected to the drive axle 9 of the tractor. The second input shaft 30 in the double-row planetary gear coupling mechanism 7 is connected to the PTO motor 13. The PTO motor 13 is connected to the PTO motor controller 15. The third output shaft 25 in the double-row planetary gear coupling mechanism 7 is connected to the rotary tillage mechanism 10. The battery pack 16 is connected to the BMS controller 17. The BMS controller 17 is connected to the battery charger 18. The coupler controller 12 is respectively connected to the synchronizer 24, the metal belt continuously variable transmission mechanism 26, the first electromagnetic lock 20, the second electromagnetic lock 22, and the third electromagnetic lock 28 in the double-row planetary gear coupling mechanism 7 to form the described series-parallel hybrid tractor mechanical coupling device.

[0050] During specific implementation, the control system of the mechanical coupling device is composed of the BMS controller 17, the engine controller 2, the ISG motor controller 11, the coupler controller 12, the PTO motor controller 13, the vehicle controller 1, and the distribution box 14 connected by circuits. The vehicle controller 1 is used to control the operation of the tractor. The engine controller 2, the ISG motor controller 11, and the PTO motor controller 15 respectively control the rotation of the engine 4, the ISG motor 5, and the PTO motor 13. The coupler controller 12 controls the operation of the double-row planetary gear coupling mechanism 7. The system has a mode of only traveling, a mode of only operating, a mode of separating traveling and operating, and a mode of coupling traveling and operating.

[0051] The features of the present invention are that the series-parallel structure combines the common advantages of series and parallel; the introduction of the ISG motor 5 enables there to be no mechanical connection between the engine 4 and the drive wheels, so that through accurate power flow control, the engine 4 can always operate within its optimal efficiency range; at low speed and low load, the PTO motor 13 can directly provide output power, improving the emission performance of the vehicle and reducing environmental pollution; a mechanical coupling mechanism is designed using planetary gear sets to enable the convergence and diversion of power, achieving maximum power efficiency; the vehicle can select different coupling modes according to different working conditions, thereby improving the power performance of the whole vehicle; and due to the design of the coupling mechanism, the vehicle structure is more compact, etc.

[0052] Further, as Figure 2 shown, the double-row planetary gear coupling mechanism 7 includes a first input shaft 19, a first electromagnetic lock 20, a first planetary gear set 21, a second electromagnetic lock 22, a first output shaft 23, a synchronizer 24, a third output shaft 25, a metal belt continuously variable transmission mechanism 26, a second output shaft 27, a third electromagnetic lock 28, a second planetary gear set 29, and a second input shaft 30. The first sun gear 21s of the first planetary gear set 21 is arranged at the right end of the first input shaft 19. A first electromagnetic lock 20 is provided on the outer edge surface of the first input shaft 19 on the left side of the first planetary gear set 21. A second electromagnetic lock 22 is provided on the periphery of the first planetary gear set 21. The first planet carrier 21c of the first planetary gear set 21 is connected to the left end of the first output shaft 23. A synchronizer 24 is provided on the outer edge surface of the first output shaft 23 on the right side of the first planet carrier 21c. The driving pulley of the metal belt continuously variable transmission mechanism 26 is arranged on the first output shaft 23. The driven pulley of the metal belt continuously variable transmission mechanism 26 is arranged on the second output shaft 27. The driving pulley and the driven pulley are connected by a metal belt 2604. The fixed part 2605 of the driven pulley in the driven pulley is connected to the third output shaft 25. A third electromagnetic lock 28 for locking or unlocking the transmission of the second sun gear 29s of the second planetary gear set 29 to the second output shaft 27 is provided on the outer edge surface of the second output shaft 27. The left end of the second output shaft 27 is connected to the second sun gear 29s of the second planetary gear set 29. The second planet carrier 29c of the second planetary gear set 29 is connected to the second input shaft 30. The first ring gear 21r of the first planetary gear set 21 and the second ring gear 29r of the adjacent second planetary gear set 29 are in external meshing transmission.

[0053] During implementation, the double-row planetary gear coupler in the mechanical coupling device includes a first planetary gear set 21 and a second planetary gear set 29 arranged side by side. The first input shaft 19 of the first planetary gear set 21 is connected to the engine and the ISG motor, and the first output shaft 23 is connected to the drive axle of the tractor. The second input shaft 30 of the second planetary gear set 29 is connected to the PTO motor 13, and the second output shaft 27 is connected to the metal belt continuously variable transmission mechanism 26. The metal belt continuously variable transmission mechanism 26 drives the rotary tillage mechanism 10 to operate through the third output shaft 25;

[0054] A first input shaft 19, a first electromagnetic lock 20, a first planetary gear set 21, a second electromagnetic lock 22, a first output shaft 23, a synchronizer 24, a metal belt continuously variable transmission mechanism 26, and a transmission 8 are provided between the engine and the drive axle. The transmission is an intermediate shaft type transmission, which realizes changing the transmission ratio, switching the transmission direction, and interrupting the power transmission.

[0055] A second input shaft 30, a second planetary gear set 29, a third electromagnetic lock 28 for locking or unlocking the transmission of the second sun gear 29s in the second planetary gear set 29 to the second output shaft 27, a second output shaft 27, a metal belt continuously variable transmission mechanism 26, and a third output shaft 25 are provided between the PTO motor 13 and the rotary tillage mechanism 10.

[0056] Furthermore, as Figure 3 shown, the first planetary gear set 21 includes a first sun gear 21s, a first ring gear 21r, first planetary gears 21p, and a first planetary carrier 21c. The first planetary gears 21p are externally meshed with the first sun gear 21s, the first planetary gears 21p are internally meshed with the first ring gear 21r, the first planetary gears 21p are connected to the first planetary carrier 21c and are positioned and supported by the first planetary carrier 21c. The first ring gear 21r is connected to the second electromagnetic lock 22.

[0057] During implementation, the first input shaft 19 is connected to the engine 4, the ISG motor 5, the clutch 6, and the first electromagnetic lock 20, and the first output shaft 23 is connected to the drive axle 9 of the tractor; the first ring gear 21r of the first planetary gear set 21 is connected to the second electromagnetic lock 22. Between the first output shaft 23 of the first planetary gear set 21 and the drive axle 9, there are successively provided: a synchronizer 24 for driving the first output shaft 23, a metal belt continuously variable transmission mechanism 26, and a transmission 8;

[0058] Furthermore, as Figure 5As shown, the metal belt stepless transmission mechanism 26 includes a driving working wheel disposed on the first output shaft 23 and a driven working wheel disposed on the second output shaft 27. The driving working wheel and the driven working wheel are connected by a metal belt 2604. The driving working wheel includes a driving working wheel fixed part 2601, a driving working wheel movable part 2602, and a driving working wheel hydraulic control cylinder 2603. The driven working wheel includes a driven working wheel fixed part 2605, a driven working wheel movable part 2606, and a driven working wheel hydraulic control cylinder 2607. The driving working wheel hydraulic control cylinder 2603 and the driven working wheel hydraulic control cylinder 2607 respectively push the driving working wheel movable part 2602 and the driven working wheel movable part 2606 to work to achieve stepless transmission of the metal belt stepless transmission mechanism.

[0059] Further, as Figure 4 shown, the second planetary gear set 29 includes a second planet carrier 29c, second planet gears 29p, a second ring gear 29r, and a second sun gear 29s. The second planet gears 29p are externally meshed with the second sun gear 29s, and the second planet gears 29p are internally meshed with the second ring gear 29r. The second planet gears 29p are connected to the second planet carrier 29c and are positioned and supported by the second planet carrier 29c.

[0060] During specific implementation, the second input shaft 30 is connected to the PTO motor 13. A third electromagnetic lock 28 for locking or unlocking the transmission of the second sun gear 29s in the second planetary gear set 29 to the second output shaft 27 is provided at the second output shaft 27. The second output shaft 27 is connected to the metal belt stepless transmission mechanism 26. The metal belt stepless transmission mechanism 26 drives the rotary tillage mechanism 10 to operate through the third output shaft 25. The double-row planetary gear coupling mechanism 7 is characterized in that the first ring gear 21r of the first planetary gear set 21 is externally meshed and transmitted with the second ring gear 29r disposed adjacent thereto on the second planetary gear set 29.

[0061] Further, the BMS controller 17 controls the battery pack 16. The battery pack 16 supplies power to the PTO motor 13, the ISG motor 5, the synchronizer 24, the first electromagnetic lock 20, the second electromagnetic lock 22, and the third electromagnetic lock 28. The coupler controller 12 respectively controls the interruption and engagement of the synchronizer 24, controls the operation of the driving working wheel hydraulic control cylinder 2603 and the driven working wheel hydraulic control cylinder 2607, and controls the locking or unlocking of the first electromagnetic lock 20, the second electromagnetic lock 22, and the third electromagnetic lock 28.

[0062] Further, as Figure 6As shown, the vehicle controller 1 obtains information of the BMS controller 17, the engine controller 2, the ISG motor controller 11, the coupler controller 12, the PTO motor controller 15, and the distribution box 14 through the high-speed CAN bus, and sends control signals to the corresponding controllers and the distribution box 14 through the high-speed CAN bus, and obtains the operation information of the tractor through the low-speed CAN bus. During implementation, the operation information includes the key signal, the gearbox gear signal, the pedal position signal, the operation mode signal, and the PTO motor and shaft rotation speed signals.

[0063] Furthermore, the ISG motor 5 is connected in series with the engine 4. The mechanical energy output by the engine 4 is converted into electrical energy in the ISG motor 5, and then the ISG motor 5 is connected to the drive axle 9 for power drive. There is no mechanical connection between the engine 4 and the drive axle 9. Therefore, through accurate power flow control, the engine 4 can always operate within its optimal efficiency region;

[0064] As Figures 6 to 10 shown, a control method for a mechanical coupling device of a series-parallel hybrid tractor. After the tractor starts, the vehicle enters the system self-check status. After the vehicle is normal and the self-check passes, it can run. The vehicle controller 1 obtains the vehicle operation demand signal, and sends control signals to each controller and the distribution box 14 according to the obtained signal, so as to select different control operation modes, specifically as follows:

[0065] A. Only walking mode:

[0066] ① PTO motor independently drives the walking mode:

[0067] When the vehicle controller 1 receives a driving signal, if the vehicle speed V is less than the preset value Veb (this preset value is specified as the bottom line of the vehicle speed), when the vehicle speed is lower than this value, the engine 4 cannot operate stably, or is in a state of high fuel consumption and high emissions. The signal collector collects signals and transmits them to the vehicle controller 1. The vehicle controller 1 issues start and stop (idle) commands to the PTO motor controller 15 and the engine controller 2 respectively. The PTO motor 13 and the engine 4 receive the commands. The PTO motor 13 works independently to provide power, and the engine 4 is in an idle or stopped state. At this time, the vehicle enters the PTO motor 13 independent drive walking mode; the coupler controller 12 controls the first electromagnetic lock 20 to lock, the second electromagnetic lock 22 to disconnect, the third electromagnetic lock 28 to lock, and the synchronizer 24 to interrupt. At this time, the PTO motor 13 is in a working state. The vehicle controller 1 calculates the target speed np of the PTO motor 13, and then transmits the signal to the PTO motor controller 15. The PTO motor 13 operates at a constant speed according to the signal of the PTO motor controller 15. The sensor continuously collects the actual speed of the PTO motor 13. The vehicle controller 1 compares whether the actual speed of the PTO motor 13 is equal to np and feeds back to the PTO motor controller 15 in a timely manner, so that the PTO motor controller 15 can continuously control the speed of the PTO motor 13 and maintain the constant-speed operation of the PTO motor 13;

[0068] ② Engine-ISG motor series drive walking mode:

[0069] When the vehicle controller 1 receives a driving signal, the vehicle controller 1 calculates the real-time required power Px. When the rated power Pq of the engine-ISG motor is greater than or equal to Px, and the engine 4 can operate in the high-efficiency working range, at this time, the vehicle enters the engine-ISG motor series drive mode. The coupler controller 12 controls the first electromagnetic lock 20 to disengage, the second electromagnetic lock 22 and the third electromagnetic lock 28 to engage, and the synchronizer 24 to interrupt. At this time, the engine 4 and the ISG motor 5 are in a working state. The vehicle controller 1 calculates the target speed nq of the ISG motor 5, and then transmits the signal to the engine controller 2 and the ISG motor controller 11. The engine 4 adjusts its speed in real time according to the signal of the engine controller 2, and the ISG motor 5 adjusts its speed in real time according to the signal of the ISG motor controller 11;

[0070] ③ Parallel drive walking mode:

[0071] When the vehicle controller 1 receives the driving signal, the vehicle controller 1 calculates the real-time required power Px. When the rated power Pq of the engine-ISG motor is less than Px or the engine 4 cannot operate in the high-efficiency working range, the vehicle enters the parallel drive walking mode at this time. The coupler controller 12 controls the first electromagnetic lock 20 and the second electromagnetic lock 22 to disconnect, the third electromagnetic lock 28 to engage, and the synchronizer 24 to interrupt. At this time, the engine 4, the ISG motor 5, and the PTO motor 13 are all in the working state. The vehicle controller 1 calculates the target speed nq of the ISG motor 5 and the target speed np of the PTO motor 13 based on the maximum working efficiency distribution control strategy, and then transmits the signal to the engine controller 2, the ISG motor controller 11, and the PTO motor controller 15. The engine controller 2, the ISG motor controller 11, and the PTO motor controller 15 adjust the speed of the control components in real time according to the signal, so that the vehicle reaches the expected working condition;

[0072] B. Only operation mode:

[0073] ① PTO motor independent drive operation mode:

[0074] When the vehicle controller 1 receives the operation signal, the vehicle controller 1 calculates the real-time required power Px. When the rated power Pe of the PTO motor 13 is greater than or equal to Px, the vehicle enters the PTO motor 13 independent drive operation mode at this time. The coupler controller 12 controls the first electromagnetic lock 20 to fix the first sun gear 21s, the second electromagnetic lock 22 to engage, the third electromagnetic lock 28 to disconnect, and the synchronizer 24 to interrupt. At this time, the PTO motor 13 is in the working state. The vehicle controller 1 calculates the target speed np of the PTO motor 13, and then transmits the signal to the PTO motor controller 15. The PTO motor 13 operates at a constant speed according to the signal of the PTO motor controller 15. The sensor collects the actual speed of the PTO motor 13 in real time. The vehicle controller 1 compares whether the actual speed of the PTO motor 13 is equal to np and feeds it back to the PTO motor controller 15 in time, so that the PTO motor controller 15 can control the speed of the PTO motor 13 in real time and maintain the constant speed operation of the PTO motor 13;

[0075] ② Parallel drive operation mode

[0076] When the vehicle controller 1 receives the operation signal, the vehicle controller 1 calculates the real-time required power Px. When the rated power Pe of the PTO motor 13 < Px, the vehicle enters the parallel drive operation mode at this time. The coupler controller 12 controls the first electromagnetic lock 20 to engage, the second electromagnetic lock 22 and the third electromagnetic lock 28 to disengage, and the synchronizer 24 to interrupt. At this time, the engine 4, the ISG motor 5, and the PTO motor 13 are all in the working state. The vehicle controller 1 calculates the target speed nq of the ISG motor 5 and the target speed np of the PTO motor 13 based on the maximum working efficiency distribution control strategy, and then transmits the signal to the engine controller 2, the ISG motor controller 11, and the PTO motor controller 15. The engine controller 2, the ISG motor controller 11, and the PTO motor controller 15 perform real-time speed regulation on the control components according to the signal, so that the vehicle reaches the envisioned working condition;

[0077] C. Travel operation separation mode:

[0078] When the vehicle controller 1 enters the travel operation separation mode, the vehicle controller 1 calculates the real-time required travel power Px1 and the real-time required operation power Px2. When the rated power Pq of the engine-ISG motor ≥ Px1 and the rated power Pe of the PTO motor 13 ≥ Px2, and the engine 4 can work in the high-efficiency working range, the vehicle controller 1 sends a travel operation separation signal to the coupler controller 12 at this time. The coupler controller 12 controls the first electromagnetic lock 20 and the third electromagnetic lock 28 to interrupt, the second electromagnetic lock 22 to engage, and the synchronizer 24 to interrupt. At this time, the engine 4, the ISG motor 5, and the PTO motor 13 are all in the working state. The vehicle controller 1 calculates the target speed nq of the ISG motor 5 and the target speed np of the PTO motor 13, and then transmits the signal to the engine controller 2, the ISG motor controller 11, and the PTO motor controller 15. The engine 4 performs real-time speed regulation according to the signal of the engine controller 2. The ISG motor 5 and the PTO motor 13 operate at a constant speed according to the signals of the ISG motor controller 11 and the PTO motor controller 15. The sensors collect the actual speeds of the ISG motor 5 and the PTO motor 13 in real time. The vehicle controller 1 transmits the signal to the ISG motor controller 11 and the PTO motor controller 15 in real time by comparing the actual speeds of the ISG motor 5 and the PTO motor 13 with the target speeds of the ISG motor 5 and the PTO motor 13, and controls the speeds of the ISG motor 5 and the PTO motor 13 through the ISG motor controller 11 and the PTO motor controller 15 to keep the ISG motor 5 and the PTO motor 13 operating at a constant speed;

[0079] D. Travel operation coupling mode:

[0080] When the vehicle controller 1 enters the walking operation coupling mode, the vehicle controller 1 calculates the real-time required walking power Px1 and the real-time required operation power Px2. When the rated power Pq of the engine-ISG motor < Px1 or the rated power Pe of the PTO motor 13 < Px2 and the engine 4 cannot operate in the high-efficiency working range, at this time, the vehicle controller 1 sends a walking operation coupling signal to the coupler controller 12. The coupler controller 12 controls the first electromagnetic lock 20, the second electromagnetic lock 22, and the third electromagnetic lock 28 to disengage, the synchronizer 24 to engage, and the hydraulic control cylinders 2603 of the driving working wheel and 2607 of the driven working wheel in the metal belt continuously variable transmission mechanism 26 to work. At this time, the engine 4, the ISG motor 5, and the PTO motor 13 are all in the working state. The vehicle controller 1 calculates the target speed nq of the ISG motor 5, the target speed np of the PTO motor 13, and the pressures of the hydraulic control cylinder 2603 of the driving working wheel and the hydraulic control cylinder 2607 of the driven working wheel based on the maximum working efficiency distribution control strategy and the required speeds of the first input shaft 19 and the third output shaft 25. Then, the vehicle controller 1 transmits the signals to the engine controller 2, the ISG motor controller 11, the PTO motor controller 15, and the coupler controller 12. The engine 4 adjusts its speed in real time according to the signal from the engine controller 2. The ISG motor 5 and the PTO motor 13 adjust their speeds in real time according to the signals from the ISG motor controller 11 and the PTO motor controller 15. The hydraulic control cylinder 2603 of the driving working wheel and the hydraulic control cylinder 2607 of the driven working wheel control the transmission ratio of the metal belt continuously variable transmission mechanism 26 in real time according to the signal from the coupler controller 12. The sensors collect the actual speeds of the first input shaft 19 and the third output shaft 25 in real time. The vehicle controller 1 compares the actual speeds of the first input shaft 19 and the third output shaft 25 with the required speeds of the first input shaft 19 and the third output shaft 25, and transmits signals to the engine controller 2, the ISG motor controller 11, the PTO motor controller 15, and the coupler controller 12 in real time to control the operation of the corresponding components, so as to keep the first input shaft 19 adjusting its speed in real time and the third output shaft 25 operating at a constant speed.

[0081] This embodiment further relates to a hybrid tractor, in which the mechanical coupling device hybrid power system described above is installed. For the hybrid tractor of this embodiment, by installing the mechanical coupling device hybrid power system as above, multi-mode driving of the system can be realized, fuel consumption can be reduced, and it has good practicability.

[0082] The beneficial effects of the present invention are as follows:

[0083] 1. The series-parallel mechanical coupling device set in the present invention combines the common advantages of series and parallel; there is no mechanical connection between the engine and the driving wheels, so through accurate power flow control, the engine can always operate in its best efficiency area;

[0084] 2. The double-row planetary gear coupling mechanism 7 provided by the present invention has a more compact structure and greater load-bearing capacity because the ring gears on the first planetary gear set and the second planetary gear set are in external meshing transmission.

[0085] 3. The present invention uses an engine, an ISG motor, and a PTO motor as the power sources of the tractor. The engine and the ISG motor transmit power to the transmission drive axle, and the PTO motor independently drives power to the rotary tillage mechanism. By controlling the planetary gear coupler, the power of the engine, the ISG motor, and the PTO motor can be converged to the transmission drive axle, which can simplify the structure of the gearbox and is beneficial to the overall vehicle layout. According to different operation requirements, select appropriate working modes to improve the working efficiency and energy utilization rate of the engine.

[0086] 4. By controlling the lock, the synchronizer, and the continuously variable transmission mechanism, the present invention can flexibly switch between the only-travel mode, the only-operation mode, the travel-operation separation mode, and the travel-operation coupling mode, meet the multi-scenario operation requirements of the tractor, and improve the power performance, economy, and adaptability of the whole vehicle.

[0087] 5. By controlling the hydraulic cylinder to change the transmission ratio of the metal belt continuously variable transmission mechanism, the present invention can enable the mechanical coupling mechanism to distribute the power of the engine, the ISG motor, and the PTO motor to the drive axle and the rotary tillage mechanism based on the maximum working efficiency distribution control strategy.

[0088] 6. The power sources used in the present invention are an engine, an ISG motor, and a PTO motor. Due to the introduction of the motor, the working area of the engine can be optimized, the energy utilization efficiency can be improved, and environmental pollution can be reduced, etc.

[0089] The parts not detailed in the present invention are the prior art.

[0090] The embodiments selected herein for disclosing the invention purpose of the present invention are considered appropriate at present. However, it should be understood that the present invention is intended to include all changes and improvements of all embodiments belonging to the concept and scope of the invention.

Claims

1. A mechanical coupling device for a series-parallel hybrid tractor, comprising a vehicle controller (1), an engine controller (2), a fuel tank (3), an engine (4), an ISG motor (5), a clutch (6), a double-row planetary gear coupling mechanism (7), a transmission (8), a drive axle (9), a rotary tillage mechanism (10), an ISG motor controller (11), a coupler controller (12), a PTO motor (13), a distribution box (14), a PTO motor controller (15), a battery pack (16), a BMS controller (17), and a battery charger (18), characterized in that: The distribution box (14) is respectively connected to the vehicle controller (1), the engine controller (2), the ISG motor controller (11), the coupler controller (12), the PTO motor controller (15) and the battery pack (16). The engine controller (2) and the ISG motor controller (11) are connected in parallel. The engine controller (2) is connected to the engine (4). The engine (4) is respectively connected to the fuel tank (3) and the ISG motor (5). The ISG motor (5) is connected to the ISG motor controller (11). The ISG motor (5) is connected to the clutch (6). The clutch (6) is connected to the first input shaft (19) in the double-row planetary gear coupling mechanism (7). The first output shaft (23) in the double-row planetary gear coupling mechanism (7) is connected to the transmission (8). The transmission (8) is connected to the drive axle (9) of the tractor. The second input shaft (30) in the double-row planetary gear coupling mechanism (7) is connected to the PTO motor (13). The PTO motor (13) is connected to the PTO motor controller (15). The third output shaft (25) in the double-row planetary gear coupling mechanism (7) is connected to the rotary tillage mechanism (10). The battery pack (16) is connected to the BMS controller (17). The BMS controller (17) is connected to the battery charger (18). The coupler controller (12) is respectively connected to the synchronizer (24), the metal belt continuously variable transmission mechanism (26), the first electromagnetic lock (20), the second electromagnetic lock (22) and the third electromagnetic lock (28) in the double-row planetary gear coupling mechanism (7) to form the series-parallel hybrid tractor mechanical coupling device.

2. The series-parallel hybrid tractor mechanical coupling device according to claim 1, characterized in that: The double-row planetary gear coupling mechanism (7) includes a first input shaft (19), a first electromagnetic lock (20), a first planetary gear set (21), a second electromagnetic lock (22), a first output shaft (23), a synchronizer (24), a third output shaft (25), a metal belt continuously variable transmission mechanism (26), a second output shaft (27), a third electromagnetic lock (28), a second planetary gear set (29), and a second input shaft (30). The first sun gear (21s) in the first planetary gear set (21) is arranged at the right end of the first input shaft (19). A first electromagnetic lock (20) is provided on the outer edge surface of the first input shaft (19) on the left side of the first planetary gear set (21). A second electromagnetic lock (22) is provided around the first planetary gear set (21). The first planet carrier (21c) in the first planetary gear set (21) is connected to the left end of the first output shaft (23). A synchronizer (24) is provided on the outer edge surface of the first output shaft (23) on the right side of the first planet carrier (21c). The driving working wheel in the metal belt continuously variable transmission mechanism (26) is arranged on the first output shaft (23). The driven working wheel in the metal belt continuously variable transmission mechanism (26) is arranged on the second output shaft (27). The driving working wheel and the driven working wheel are connected by a metal belt (2604). The fixed part (2605) of the driven working wheel in the driven working wheel is connected to the third output shaft (25). A third electromagnetic lock (28) for locking or unlocking the transmission of the second sun gear (29s) in the second planetary gear set (29) to the second output shaft (27) is provided on the outer edge surface of the second output shaft (27). The left end of the second output shaft (27) is connected to the second sun gear (29s) in the second planetary gear set (29). The second planet carrier (29c) in the second planetary gear set (29) is connected to the second input shaft (30). The first ring gear (21r) in the first planetary gear set (21) and the second ring gear (29r) in the adjacent second planetary gear set (29) are in external meshing transmission.

3. The series-parallel hybrid tractor mechanical coupling device according to claim 2, characterized in that: The first planetary gear set (21) includes a first sun gear (21s), a first ring gear (21r), a first planetary gear (21p), and a first planet carrier (21c). The first planetary gear (21p) is in external mesh with the first sun gear (21s). The first planetary gear (21p) is in internal mesh with the first ring gear (21r). The first planetary gear (21p) is connected to the first planet carrier (21c) and is positioned and supported by the first planet carrier (21c). The first ring gear (21r) is connected to the second electromagnetic lock (22).

4. The series-parallel hybrid tractor mechanical coupling device according to claim 1, characterized in that: The metal belt stepless transmission mechanism (26) includes a driving working wheel disposed on the first output shaft (23) and a driven working wheel disposed on the second output shaft (27). The driving working wheel and the driven working wheel are connected by a metal belt (2604). The driving working wheel includes a driving working wheel fixed part (2601), a driving working wheel movable part (2602) and a driving working wheel hydraulic control cylinder (2603). The driven working wheel includes a driven working wheel fixed part (2605), a driven working wheel movable part (2606) and a driven working wheel hydraulic control cylinder (2607). The driving working wheel hydraulic control cylinder (2603) and the driven working wheel hydraulic control cylinder (2607) respectively push the driving working wheel movable part (2602) and the driven working wheel movable part (2606) to work to achieve stepless transmission of the metal belt type stepless transmission mechanism.

5. The series-parallel hybrid tractor mechanical coupling device according to claim 2, characterized in that: The second planetary gear set (29) includes a second planet carrier (29c), second planet gears (29p), a second ring gear (29r) and a second sun gear (29s). The second planet gears (29p) are externally meshed with the second sun gear (29s), and the second planet gears (29p) are internally meshed with the second ring gear (29r). The second planet gears (29p) are connected to the second planet carrier (29c) and are positioned and supported by the second planet carrier (29c).

6. The series-parallel hybrid tractor mechanical coupling device according to claim 1, wherein: The BMS controller (17) controls the battery pack (16). The battery pack (16) supplies power to the PTO motor (13), the ISG motor (5), the synchronizer (24), the first electromagnetic lock (20), the second electromagnetic lock (22) and the third electromagnetic lock (28). The coupler controller (12) respectively controls the interruption and engagement of the synchronizer (24), controls the operation of the driving working wheel hydraulic control cylinder (2603) and the driven working wheel hydraulic control cylinder (2607), and controls the locking or unlocking of the first electromagnetic lock (20), the second electromagnetic lock (22) and the third electromagnetic lock (28).

7. The series-parallel hybrid tractor mechanical coupling device according to claim 1, characterized in that: The vehicle controller (1) obtains information of the BMS controller (17), the engine controller (2), the ISG motor controller (11), the coupler controller (12), the PTO motor controller (15) and the distribution box (14) through the high-speed CAN bus, and sends control signals to the corresponding controllers and the distribution box (14) through the high-speed CAN bus, and obtains the operation information of the tractor through the low-speed CAN bus.

8. The series-parallel hybrid tractor mechanical coupling device according to claim 7, wherein: The operation information includes a key signal, a gearbox gear position signal, a pedal position signal, an operation mode signal, and PTO motor and rotating shaft speed signals.

9. The series-parallel hybrid tractor mechanical coupling device according to claim 1, characterized in that: The ISG motor (5) is connected in series with the engine (4). The mechanical energy output by the engine (4) is converted into electrical energy in the ISG motor (5), and then the ISG motor (5) is connected to the drive axle (9) for power drive.

10. The control method of a series-parallel hybrid tractor mechanical coupling device according to any one of claims 1 to 9, characterized in that: The control method is as follows: after the tractor starts, the vehicle enters the system self-check status. After the vehicle is normal and the self-check passes, it can run. The vehicle controller (1) obtains the vehicle operation demand signal and sends control signals to each controller and the distribution box (14) according to the obtained signal, so as to select different control operation modes, specifically as follows: A. Only walking mode: ① PTO motor independent drive walking mode: When the vehicle controller (1) receives the walking signal, if the vehicle speed V is less than the preset value Veb, when the vehicle speed is lower than this value, the engine (4) cannot operate stably, or is in a high fuel consumption and high emission state. The signal collector collects the signal and transmits it to the vehicle controller (1). The vehicle controller (1) sends start and stop commands to the PTO motor controller (15) and the engine controller (2) respectively. The PTO motor (13) and the engine (4) receive the commands. The PTO motor (13) works alone to provide power, and the engine (4) is in the idle or stop state. At this time, the vehicle enters the PTO motor (13) independent drive walking mode; the coupler controller (12) controls the first electromagnetic lock (20) to lock, the second electromagnetic lock (22) to disconnect, the third electromagnetic lock (28) to lock, and the synchronizer (24) to interrupt. At this time, the PTO motor (13) is in the working state. The vehicle controller (1) calculates the target speed np of the PTO motor (13), and then transmits the signal to the PTO motor controller (15). The PTO motor (13) operates at a constant speed according to the signal of the PTO motor controller (15). The sensor continuously collects the actual speed of the PTO motor (13). The vehicle controller (1) compares whether the actual speed of the PTO motor (13) is equal to np and feeds it back to the PTO motor controller (15) in time, so that the PTO motor controller (15) can continuously control the speed of the PTO motor (13) to maintain the constant speed operation of the PTO motor (13); ② Engine-ISG motor series drive walking mode: When the vehicle controller (1) receives the walking signal, the vehicle controller (1) calculates the real-time demand power Px. When the rated power Pq of the engine-ISG motor is greater than or equal to Px, and the engine (4) can work in the high-efficiency working range, at this time, the vehicle enters the engine-ISG motor series drive mode. The coupler controller (12) controls the first electromagnetic lock (20) to disengage, the second electromagnetic lock (22) and the third electromagnetic lock (28) to engage, and the synchronizer (24) to interrupt. At this time, the engine (4) and the ISG motor (5) are in the working state. The vehicle controller (1) calculates the target speed nq of the ISG motor (5), and then transmits the signal to the engine controller (2) and the ISG motor controller (11). The engine (4) adjusts the speed in real time according to the signal of the engine controller (2), and the ISG motor (5) adjusts the speed in real time according to the signal of the ISG motor controller (11); ③ Parallel drive walking mode: When the vehicle controller (1) receives the driving signal, the vehicle controller (1) calculates the real-time required power Px. When the rated power Pq of the engine-ISG motor < Px or the engine (4) cannot operate in the high-efficiency operating range, the vehicle enters the parallel drive mode. The coupler controller (12) controls the first electromagnetic lock (20) and the second electromagnetic lock (22) to disconnect, the third electromagnetic lock (28) to engage, and the synchronizer (24) to disengage. At this time, the engine (4), the ISG motor (5), and the PTO motor (13) are all in the operating state. The vehicle controller (1) calculates the target speed nq of the ISG motor (5) and the target speed np of the PTO motor (13) based on the maximum operating efficiency distribution control strategy, and then transmits the signal to the engine controller (2), the ISG motor controller (11), and the PTO motor controller (15). The engine controller (2), the ISG motor controller (11), and the PTO motor controller (15) adjust the speed of the control components in real time according to the signal, so that the vehicle reaches the desired operating condition; B. Only operation mode: ① PTO motor independent drive operation mode: When the vehicle controller (1) receives the operation signal, the vehicle controller (1) calculates the real-time required power Px. When the rated power Pe of the PTO motor (13) ≥ Px, the vehicle enters the PTO motor (13) independent drive operation mode. The coupler controller (12) controls the first electromagnetic lock (20) to fix the first sun gear (21s), the second electromagnetic lock (22) to engage, the third electromagnetic lock (28) to disconnect, and the synchronizer (24) to disengage. At this time, the PTO motor (13) is in the operating state. The vehicle controller (1) calculates the target speed np of the PTO motor (13), and then transmits the signal to the PTO motor controller (15). The PTO motor (13) operates at a constant speed according to the signal of the PTO motor controller (15). The sensor real-time collects the actual speed of the PTO motor (13). The vehicle controller (1) compares whether the actual speed of the PTO motor (13) is equal to np and feeds it back to the PTO motor controller (15) in time, so that the PTO motor controller (15) can control the speed of the PTO motor (13) in real time and maintain the constant speed operation of the PTO motor (13); ② Parallel drive operation mode When the vehicle controller (1) receives the operation signal, the vehicle controller (1) calculates the real-time required power Px. When the rated power Pe of the PTO motor (13) < Px, the vehicle enters the parallel drive operation mode. The coupler controller (12) controls the first electromagnetic lock (20) to engage, the second electromagnetic lock (22) and the third electromagnetic lock (28) to disengage, and the synchronizer (24) to interrupt. At this time, the engine (4), the ISG motor (5), and the PTO motor (13) are all in the working state. The vehicle controller (1) calculates the target speed nq of the ISG motor (5) and the target speed np of the PTO motor (13) based on the maximum working efficiency distribution control strategy, and then transmits the signal to the engine controller (2), the ISG motor controller (11), and the PTO motor controller (15). The engine controller (2), the ISG motor controller (11), and the PTO motor controller (15) adjust the speed of the control components in real time according to the signal, so that the vehicle reaches the expected working condition; C. Travel operation separation mode: When the vehicle controller (1) enters the travel operation separation mode, the vehicle controller (1) calculates the real-time required travel power Px1 and the real-time required operation power Px2. When the rated power Pq of the engine-ISG motor ≥ Px1 and the rated power Pe of the PTO motor (13) ≥ Px2, and the engine (4) can operate in the high-efficiency working range, the vehicle controller (1) sends a travel operation separation signal to the coupler controller (12). The coupler controller (12) controls the first electromagnetic lock (20) and the third electromagnetic lock (28) to interrupt, the second electromagnetic lock (22) to engage, and the synchronizer (24) to interrupt. At this time, the engine (4), the ISG motor (5), and the PTO motor (13) are all in the working state. The vehicle controller (1) calculates the target speed nq of the ISG motor (5) and the target speed np of the PTO motor (13), and then transmits the signal to the engine controller (2), the ISG motor controller (11), and the PTO motor controller (15). The engine (4) adjusts the speed in real time according to the signal of the engine controller (2). The ISG motor (5) and the PTO motor (13) operate at a constant speed according to the signals of the ISG motor controller (11) and the PTO motor controller (15). The sensor collects the actual speeds of the ISG motor (5) and the PTO motor (13) in real time. The vehicle controller (1) compares the actual speeds of the ISG motor (5) and the PTO motor (13) with the target speeds of the ISG motor (5) and the PTO motor (13) and transmits the signal to the ISG motor controller (11) and the PTO motor controller (15) in real time. The speeds of the ISG motor (5) and the PTO motor (13) are controlled by the ISG motor controller (11) and the PTO motor controller (15) to keep the ISG motor (5) and the PTO motor (13) operating at a constant speed; D. Travel operation coupling mode: When the vehicle controller (1) enters the walking operation coupling mode, the vehicle controller (1) calculates the real-time required walking power Px1 and the real-time required operation power Px2. When the rated power Pq of the engine-ISG motor < Px1 or the rated power Pe of the PTO motor (13) < Px2 and the engine (4) cannot operate in the high-efficiency working range, at this time, the vehicle controller (1) sends a walking operation coupling signal to the coupler controller (12). The coupler controller (12) controls the first electromagnetic lock (20), the second electromagnetic lock (22) and the third electromagnetic lock (28) to disengage, the synchronizer (24) to engage, and the hydraulic control cylinders (2603) of the driving working wheel and the hydraulic control cylinders (2607) of the driven working wheel in the metal belt continuously variable transmission mechanism (26) to work. At this time, the engine (4), the ISG motor (5) and the PTO motor (13) are all in the working state. The vehicle controller (1) calculates the target speed nq of the ISG motor (5), the target speed np of the PTO motor (13) and the pressures of the hydraulic control cylinders (2603) of the driving working wheel and the hydraulic control cylinders (2607) of the driven working wheel based on the maximum working efficiency distribution control strategy and the required speeds of the first input shaft (19) and the third output shaft (25). Then, it transmits the signals to the engine controller (2), the ISG motor controller (11), the PTO motor controller (15) and the coupler controller (12). The engine (4) adjusts its speed in real time according to the signal from the engine controller (2). The ISG motor (5) and the PTO motor (13) adjust their speeds in real time according to the signals from the ISG motor controller (11) and the PTO motor controller (15). The hydraulic control cylinders (2603) of the driving working wheel and the hydraulic control cylinders (2607) of the driven working wheel control the transmission ratio of the metal belt continuously variable transmission mechanism (26) in real time according to the signal from the coupler controller (12). The sensors collect the actual speeds of the first input shaft (19) and the third output shaft (25) in real time. The vehicle controller (1) compares the actual speeds of the first input shaft (19) and the third output shaft (25) with the required speeds of the first input shaft (19) and the third output shaft (25), and transmits signals to the engine controller (2), the ISG motor controller (11), the PTO motor controller (15) and the coupler controller (12) in real time to control the operation of the corresponding components, so as to keep the first input shaft (19) adjusting its speed in real time and the third output shaft (25) operating at a constant speed.

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