A range extended agricultural hybrid transmission and a control method thereof

Abstract

This invention belongs to the field of gearbox technology, and specifically relates to a range-extended agricultural hybrid transmission and its control method. It includes a housing and a first transmission system, a second transmission system, and a third transmission system sequentially arranged within it. This invention utilizes the millisecond-level response characteristics of the drive motor to provide torque compensation during sudden changes in heavy load, completely solving the problem of diesel engine stalling; it also features vehicle charging and regenerative braking functions, significantly improving the overall vehicle energy utilization rate; while maintaining the engine operating in its most efficient range and with an absolutely constant PTO speed, it utilizes the cooperation of an independent motor and a hydraulic system to achieve free and stepless adjustment of the tractor speed without interference; before switching between adjacent gear positions, the stepless adjustment of the hydraulic pump displacement actively smooths out the speed difference between the components to be engaged, eliminating clutch slippage, overheating, power interruption, and mechanical jerking during traditional tractor gear shifting.

Description

Technical Field

[0001] This invention relates to the field of gearbox technology, specifically to a range-extended agricultural hybrid power transmission and its control method. Background Technology

[0002] Currently, heavy-duty agricultural machinery transmission systems are developing towards continuously variable transmission (CVT) and multi-source power coupling. Existing hydraulic mechanical CVTs rely solely on a single power source, depending on the diesel engine for speed adjustment when facing sudden changes in heavy load conditions. This results in sluggish dynamic response and a high risk of engine stalling. Furthermore, these systems lack energy recovery and storage mechanisms, leading to low overall vehicle kinetic energy utilization efficiency and high fuel consumption. Traditional tractor transmission configurations struggle to achieve complete decoupling between travel speed and PTO speed. In precision operations such as combine harvesting and rotary tillage, which require constant PTO speed, adjusting the vehicle speed often causes PTO speed fluctuations or power interference, severely impacting work quality. Currently, no effective comprehensive solution has been proposed that balances high responsiveness and fully decoupled control, addressing these industry pain points such as poor dynamic response, susceptibility to stalling under heavy loads, low energy utilization, and difficulties in PTO decoupling control. Summary of the Invention

[0003] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0004] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0005] A range-extended agricultural hybrid power transmission includes a housing and a first transmission system, a second transmission system, and a third transmission system sequentially disposed therein;

[0006] The first transmission system includes: an engine connected to an engine output shaft; a generator whose rotor is connected at one end to the engine output shaft and at the other end to a first power input shaft; a first power input shaft connected to a PTO power output shaft via the driving and driven ends of a clutch A; and a PTO power output flange connected to the PTO power output shaft.

[0007] The second transmission system includes: a power battery, which is electrically connected to a drive motor and a generator respectively; a drive motor, which is connected to a second power input shaft; a gear C1 connected to one end of the second power input shaft and a hydraulic pump input shaft connected to the other end; a hydraulic pump, which is connected to a hydraulic motor through a hydraulic pipe; and a hydraulic motor, which is connected to a hydraulic power input shaft.

[0008] The third transmission system includes: a first intermediate shaft with gear B1 mounted thereon, gear B1 meshing with gear C1; a second intermediate shaft connected to the first intermediate shaft via clutch B; a planetary gear set assembly including a sun gear, planet gears, a planet carrier, and a ring gear, the sun gear being fixed on the second intermediate shaft, the planet gears being pivotally connected to the planet carrier and meshing with the sun gear and the ring gear respectively; the planet carrier being connected to the hydraulic power input shaft via a gear switching mechanism including a sliding sleeve; a third intermediate shaft connected to the planet carrier; and a vehicle power output shaft connected to the ring gear or the third intermediate shaft, one end of which is fixed with a vehicle drive flange.

[0009] In a preferred embodiment of the range-extended agricultural hybrid power transmission described in this invention, the first power input shaft is connected to the PTO power output shaft via the driving and driven ends of clutch A; the second power input shaft is connected to the hydraulic pump input shaft via the driving and driven ends of clutch C; the intermediate first shaft is connected to the intermediate second shaft via the driving and driven ends of clutch B; the planetary carrier is fixedly connected to the housing via brake Q; the gear ring is fixedly connected to the housing via brake E, and the gear ring is connected to the planetary carrier via the driving and driven ends of clutch W; the gear ring is connected to the vehicle power output shaft via the driving and driven ends of clutch D and the clutch housing; and the intermediate third shaft is connected to the vehicle power output shaft via the driving and driven ends of clutch F and the clutch housing.

[0010] In a preferred embodiment of the range-extended agricultural hybrid power transmission described in this invention, the planetary carrier is connected to the hydraulic power input shaft via a gear switching mechanism. The gear switching mechanism includes gears B2 and B3 loosely fitted on the planetary carrier, a splined hub fixedly connected to the planetary carrier, and a sliding sleeve slidably connected to the splined hub via an inner spline. Gears C2 and C3 are fixedly mounted on the hydraulic power input shaft. Gears B2 and C2 are always meshed, and gears B3 and C3 are always meshed. The sliding sleeve can slide axially along the splined hub, selectively engaging with either gear B2 or gear B3, thereby transmitting different power transmission ratios from the hydraulic power input shaft to the planetary carrier.

[0011] A control method for a range-extended agricultural hybrid power transmission includes the following steps:

[0012] Vehicle energy management and range extension control steps;

[0013] Multi-source power operation mode switching control steps;

[0014] Active synchronization switching control steps for adjacent continuously variable transmission (CVT) segments;

[0015] PTO and walking speed decoupling control steps.

[0016] As a preferred solution of the control method of the range-extended agricultural hybrid transmission described in the present invention, the vehicle energy management and range extension control steps specifically include:

[0017] The vehicle controller continuously obtains the state of charge of the power battery and the parsed vehicle demand power;

[0018] When it is judged that the state of charge of the power battery is greater than the preset high battery charge threshold and the vehicle demand power is less than the preset pure electric working power threshold, the engine is controlled to stop, and the system enters the pure electric priority driving mode, and the power battery alone supplies power to the drive motor;

[0019] When it is judged that the state of charge of the power battery is lower than the preset low battery charge threshold, or the vehicle demand power is greater than or equal to the pure electric working power threshold, the engine is controlled to start, and the system enters the range extension and driving charging mode, and the engine drives the generator to generate electricity; if the output power of the generator is greater than the vehicle demand power, the excess electric energy is controlled to be charged into the power battery; if the output power of the generator is less than the vehicle demand power, the power battery and the generator are controlled to jointly supply power to the drive motor.

[0020] As a preferred solution of the control method of the range-extended agricultural hybrid transmission described in the present invention, the multi-source power operation mode switching control steps specifically include:

[0021] The vehicle controller continuously collects the current vehicle speed v and the target load signal, and compares them with the preset first vehicle speed threshold v1 and the second vehicle speed threshold v2, where v1 < v2;

[0022] When v < v1 and a start or fine movement instruction is received, the control system enters the pure hydraulic low-speed fine movement and start mode: the mechanical power transmission from the drive motor to the planetary gear set is cut off, and the power is only transmitted to the planet carrier through the hydraulic pump and the hydraulic motor and output outward;

[0023] When v1 ≤ v ≤ v2 and the vehicle is in a continuous operation condition, the control system enters the electro-mechanical-hydraulic hybrid continuously variable speed mode: the mechanical power output by the drive motor is input to the sun gear, and the hydraulic power output by the hydraulic system is input to the planet carrier. The two-way power is coupled in the planetary gear set and uniformly output by the ring gear. The vehicle controller realizes continuously variable speed by adjusting the displacement of the hydraulic pump in real time to change the speed of the planet carrier;

[0024] When v > v2 and the vehicle is in a low-load cruise or transfer condition, the control system enters the pure mechanical high-speed transfer mode: the power input of the hydraulic circuit is separated and the ring gear is fixed, and the power is only transmitted to the intermediate third shaft through the mechanical gear and output outward.

[0025] As a preferred embodiment of the control method for a range-extended agricultural hybrid transmission according to the present invention, the active synchronous shift control step for adjacent continuously variable transmission (CVT) segments specifically includes:

[0026] When switching between adjacent segments in the electromechanical-hydraulic hybrid continuously variable transmission mode, the following steps are performed: maintain the engagement of the actuator in the current working segment, collect the speed of the active end and the driven end of the target actuator that is about to be engaged in real time, and calculate the speed difference between the active end and the driven end.

[0027] Perform active hydraulic synchronization adjustment: Based on the speed difference, continuously and steplessly change the displacement of the hydraulic pump to make the speed difference between the active end and the driven end of the target actuator approach zero;

[0028] Perform flexible switching with low speed difference: When the absolute value of the speed difference is less than the preset safety synchronization threshold, control the target actuator to engage and simultaneously disengage the actuator of the original working segment.

[0029] As a preferred embodiment of the control method for a range-extended agricultural hybrid power transmission according to the present invention, the PTO and travel speed decoupling control step specifically includes:

[0030] When receiving and responding to the PTO constant speed operation command, the engine and PTO constant speed lock is executed: the vehicle controller controls the engine to start and lock at the target constant speed, and at the same time controls the engine's power to be transmitted to the PTO power output shaft at a constant speed.

[0031] Power splitting and energy balancing: The mechanical power output of the engine is physically split. The first part satisfies the load of the PTO power output shaft, and the second part of the surplus power drives the generator to generate electricity. The electrical energy is distributed to the drive motor or charged into the power battery by the vehicle controller.

[0032] Independent stepless adjustment of walking speed: While maintaining the constant speed of the PTO power output shaft, the vehicle controller independently sends torque and speed commands to the drive motor according to the target driving speed, and simultaneously adjusts the displacement of the hydraulic pump, so that the actual walking speed of the vehicle is determined by the speed of the drive motor and the transmission ratio of the hydraulic system, and is completely decoupled from the engine speed.

[0033] Compared with the prior art, the beneficial effects of the present invention are: (1) heavy load anti-stalling and high efficiency energy saving: by utilizing the millisecond-level response characteristics of the drive motor, torque compensation is provided during sudden heavy load changes, which completely solves the problem of diesel engine stalling; at the same time, it has the functions of driving charging and braking energy recovery, which greatly improves the energy utilization rate of the whole vehicle.

[0034] (2) Complete decoupling of walking and PTO: Under the premise of keeping the engine running in the most efficient range and the PTO speed absolutely constant, the tractor speed can be freely and steplessly adjusted by using the cooperation of independent motor and hydraulic system, without interference between them.

[0035] (3) Zero-impact seamless shifting: Before switching between adjacent shifts, the stepless adjustment of the hydraulic pump displacement actively smooths out the speed difference of the components to be engaged, eliminating clutch slippage and heat generation, power interruption and mechanical jerking during traditional tractor shifting. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0037] Figure 1 This is a schematic diagram of a range-extended agricultural hybrid power transmission according to the present invention;

[0038] Figure 2 This is a diagram of the mechanical first gear power transmission route of the present invention;

[0039] Figure 3 This is a mechanical second-gear power transmission route diagram for the present invention;

[0040] Figure 4 This is a diagram illustrating the power transmission route for the mechanical reverse gear in this invention.

[0041] Figure 5 This is a diagram of the hydraulic power transmission route for the first stage of this invention;

[0042] Figure 6 This is a hydraulic two-stage power transmission route diagram for the present invention;

[0043] Figure 7 This is a power transmission route diagram for the hydraulic reversing section 1 of the present invention;

[0044] Figure 8 This is a diagram showing the power transmission route for the hydraulic reversing mechanism in this invention.

[0045] Figure 9 This is a diagram of the hybrid power transmission route of the present invention.

[0046] Figure 10 This is a schematic diagram of the hybrid two-stage power transmission route of the present invention;

[0047] Figure 11 This is a power transmission route diagram for the first stage of the hybrid reversing circuit of the present invention;

[0048] Figure 12 This is a power transmission route diagram for the hybrid reversing two-stage system of the present invention.

[0049] In the diagram: 1-Engine; 2-Engine output shaft; 3-Generator; 4-Intermediate first shaft; 5-First power input shaft; 6-Clutch B; 7-Clutch A; 8-Gear B2; 9-Intermediate second shaft; 10-Sliding sleeve; 11-Brake Q; 12-Brake E; 13-Clutch W; 14-Planetary carrier; 15-PTO power output shaft; 16-PTO power output flange; 17-Clutch D; 18-Clutch F; 19-Vehicle drive flange; 20-Vehicle power output shaft ; 21-Intermediate third shaft; 22-Clutch housing; 23-Sun gear; 24-Ring gear; 25-Planet gear; 26-Gear B3; 27-Gear C3; 28-Splined hub; 29-Gear C2; 30-Hydraulic power input shaft; 31-Hydraulic motor; 32-Hydraulic pipe; 33-Hydraulic pump; 34-Hydraulic pump input shaft; 35-Clutch C; 36-Second power input shaft; 37-Drive motor; 38-Gear C1; 39-Power battery; 40-Gear B1; 41-Housing.

[0050] Figures 2-12 In the diagram, red lines indicate the direction of engine rotation, green lines indicate the direction of engine rotation opposite, yellow lines indicate electrical transmission, and blue lines indicate hydraulic transmission. Detailed Implementation

[0051] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0052] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0054] This invention achieves intelligent scheduling and peak shaving of vehicle energy through a range-extended architecture and energy management strategy, providing motor torque compensation and anti-stalling protection during heavy-load start-up; through engine constant speed locking and electromechanical-hydraulic dual-flow transmission architecture, it achieves complete physical and control decoupling of PTO constant speed output and vehicle continuously variable transmission; it provides intelligent switching of multi-source power operation modes and hydraulic active synchronous shifting strategy, achieving zero-impact stepless speed regulation and high-speed pure mechanical high-efficiency transmission across the entire speed range.

[0055] For details, please refer to Figure 1 A range-extended agricultural hybrid transmission mainly includes the following components:

[0056] Engine and First Transmission Assembly: Engine 1 provides power input to this assembly. The stator of generator 3 is fixed to housing 41, and one end of the rotor of generator 3 is connected to the engine output shaft 2. The first power input shaft 5 is connected to the other end of the generator 3 rotor. The driving end of clutch A7 is connected to the first power input shaft 5, and the driven end of clutch A7 is connected to PTO power output shaft 15. PTO power output flange 16 is connected to PTO power output shaft 15.

[0057] When engine 1 is running, its power is transmitted to engine output shaft 2, which in turn drives the rotor of generator 3 to rotate. Generator 3 charges the power battery 39 according to the vehicle's needs. The rotor of generator 3 then transmits mechanical power to the first power input shaft 5, which drives the driving end of clutch A7 to rotate. When clutch A7 is engaged, the driving and driven ends of clutch A7 rotate synchronously. The driven end of clutch A7 drives the PTO power output shaft 15 to rotate, and the power is ultimately transmitted from the PTO power output shaft 15 to the PTO power output flange 16.

[0058] Second transmission assembly: Drive motor 37 provides power input to this assembly, and power battery 39 provides electrical energy to drive motor 37. The stator of drive motor 37 is fixed to housing 41, and one end of the rotor of drive motor 37 is connected to the second power input shaft 36. Gear C1 38 is fixedly mounted on the second power input shaft 36. The driving end of clutch C35 is connected to the second power input shaft 36, and the driven end of clutch C35 is connected to the hydraulic pump input shaft 34. The housing of hydraulic pump 33 is fixed to housing 41, and the hydraulic oil port of hydraulic pump 33 is sealed to the inlet and outlet ports of hydraulic motor 31 through hydraulic pipe 32. Gears C2 29 and C3 27 are fixedly mounted on hydraulic power input shaft 30.

[0059] When the drive motor 37 is working, the power battery 39 supplies power to the drive motor 37. The rotor of the drive motor 37 transmits power to the second power input shaft 36, which drives the driving end of the clutch C35 to rotate. When the clutch C35 is engaged, the driving end and the driven end of the clutch C35 rotate synchronously, and the driven end drives the hydraulic pump input shaft 34 to rotate. After being driven, the hydraulic pump 33 converts mechanical energy into hydraulic energy, generating high-pressure hydraulic oil. This high-pressure hydraulic oil enters the hydraulic motor 31 through the hydraulic pipe 32, driving the hydraulic motor 31 to work and converting hydraulic energy into mechanical energy, ultimately driving the hydraulic power input shaft 30 to rotate. Gears C2 29 and C3 27 rotate synchronously with the hydraulic power input shaft 30.

[0060] The third transmission assembly consists of: Gear B1 40 fixedly mounted on the intermediate first shaft 4; the driving end of clutch B6 connected to the intermediate first shaft 4; and the driven end of clutch B6 connected to the intermediate second shaft 9. Sun gear 23 is fixedly mounted on the intermediate second shaft 9. Planet gears 25 are pivotally connected to the planet carrier 14 and mesh with sun gear 23 and ring gear 24, respectively. Gears B2 8 and B3 26 are loosely fitted on the planet carrier 14, and sliding sleeve 10 is slidably connected to the external spline of spline hub 28 via internal splines; gear B2 8 is constantly meshed with gear C2 29, and gear B3 26 is constantly meshed with gear C3 27. Spline hub 28 is fixedly connected to the planet carrier 14. The driving end of brake Q11 is connected to the planet carrier 14, and brake Q11 is fixed to housing 41; the driving end of brake E12 is connected to ring gear 24, and brake E12 is fixed to housing 41. The driving end of clutch W13 is connected to the gear ring 24, and the driven end of clutch W13 is connected to the planet carrier 14.

[0061] When the sliding sleeve 10 is in the neutral position, gears B2 8 and B3 26 rotate freely on the planet carrier 14.

[0062] When the sliding sleeve 10 is in the left position, the power of gear B2 8 is transmitted to the spline hub 28 through the sliding sleeve 10, and the spline hub 28 drives the planetary carrier 14 to rotate.

[0063] When the sliding sleeve 10 is in the right position, the power of gear B3 26 is transmitted to the spline hub 28 through the sliding sleeve 10, and the spline hub 28 drives the planetary carrier 14 to rotate.

[0064] Gear B1 40 rotates in tandem with gear C1 38, and the intermediate first shaft 4 drives the driving end of clutch B6 to rotate. When clutch B6 is engaged, the driving end and driven end of clutch B6 rotate synchronously, and the driven end of clutch B6 drives the intermediate second shaft 9 to rotate. The sun gear 23 rotates together with the intermediate second shaft 9.

[0065] When brake Q11 and clutch D17 are engaged, and clutch W13 and brake E12 are disengaged, planetary carrier 14 is fixed to housing 41 via brake Q11. Power is transmitted from sun gear 23 to ring gear 24, at which point the rotation direction of ring gear 24 is opposite to that of sun gear 23. Clutch D17 drives clutch housing 22 to rotate, and power is then transmitted from clutch housing 22 to vehicle power output shaft 20, ultimately driving vehicle drive flange 19 to rotate.

[0066] When clutches W13 and D17 are engaged, and brakes Q11 and E12 are disengaged, planetary carrier 14 and ring gear 24 are locked. Power is transmitted directly from sun gear 23 to ring gear 24, and the ring gear 24 rotates in the same direction as sun gear 23. Clutch D17 drives clutch housing 22 to rotate, and power is then transmitted from clutch housing 22 to the vehicle's power output shaft 20, ultimately driving the vehicle's drive flange 19 to rotate.

[0067] When brake E12 and clutch F18 are engaged, and brake Q11 and clutch W13 are disengaged, the gear ring 24 is fixed to the housing 41 via brake E12. Power is transmitted from the sun gear 23 to the planet carrier 14, and the intermediate third shaft 21 rotates with the planet carrier 14. Clutch F18 drives the clutch housing 22 to rotate, and power is then transmitted from the clutch housing 22 to the vehicle's power output shaft 20, ultimately driving the vehicle's drive flange 19 to rotate.

[0068] Table 1: State Logic Table of Shift Actuators under Various Operating Modes of the Transmission

[0069]

[0070] "1" engages, "0" disengages. During the reversing phase, the hydraulic motor rotates in the opposite direction.

[0071] When PTO power output is required, clutch A7 engages, and power is output from engine 1 to engine output shaft 2, transmitted through the rotor of generator 3 to the first power input shaft 5, and then transmitted through the driving and driven ends of clutch A7 to PTO power output shaft 15, and finally transmitted to PTO power output flange 16 for outward output.

[0072] Figure 2 The power transmission route for the first gear of this invention is as follows: Power is output from the rotor of the drive motor 37 to the second power input shaft 36. Gear C1 38 transmits power to gear B1 40 through gear meshing, and gear B1 40 drives the intermediate first shaft 4 to rotate. At this time, the sliding sleeve 10 is in the neutral position, and the hydraulic circuit is physically disconnected. Clutch B6 is engaged, and power is transmitted from the intermediate first shaft 4 to the intermediate second shaft 9 through the driving and driven ends of clutch B6. The sun gear 23 rotates with the intermediate second shaft 9. Brake E12 is engaged, and the gear ring 24 is fixed to the housing 41 through brake E12. The planetary gear 25 rotates with the sun gear 23 and revolves around the sun gear 23. The planet carrier 14 rotates with the planetary gear 25. The planet carrier 14 drives the intermediate third shaft 21 to rotate. Clutch F18 is engaged, and power is transmitted through the intermediate third shaft 21 and clutch F18 to the vehicle power output shaft 20, ultimately driving the vehicle drive flange 19 to rotate.

[0073] Figure 3The mechanical second-gear power transmission route of this invention is as follows: Power is output from the rotor of the drive motor 37 to the second power input shaft 36. Gear C1 38 transmits power to gear B1 40 through gear meshing, and gear B1 40 drives the intermediate first shaft 4 to rotate. At this time, the sliding sleeve 10 is in the neutral position, and the hydraulic circuit is physically disconnected. Clutch B6 is engaged, and power is transmitted from the intermediate first shaft 4 to the intermediate second shaft 9 through the driving and driven ends of clutch B6. The sun gear 23 rotates with the intermediate second shaft 9. At this time, clutches W13 and D17 are engaged, and brakes Q11 and E12 are disengaged. The planetary carrier 14 and the ring gear 24 are locked, and power is transmitted from the sun gear 23 to the ring gear 24. At this time, the rotation direction of the ring gear 24 is the same as that of the sun gear 23. Clutch D17 drives the clutch housing 22 to rotate, and power is then transmitted from the clutch housing 22 to the vehicle power output shaft 20, which ultimately drives the vehicle drive flange 19 to rotate.

[0074] Figure 4 The power transmission route for the mechanical reverse gear of this invention is as follows: Power is output from the rotor of the drive motor 37 to the second power input shaft 36. Gear C1 38 transmits power to gear B1 40 through gear meshing, and gear B1 40 drives the intermediate first shaft 4 to rotate. At this time, the sliding sleeve 10 is in the neutral position, and the hydraulic circuit is physically disconnected. Clutch B6 is engaged, and power is transmitted from the intermediate first shaft 4 to the intermediate second shaft 9 through the driving and driven ends of clutch B6. The sun gear 23 rotates with the intermediate second shaft 9. At this time, brake Q11 and clutch D17 are engaged, and clutch W13 and brake E12 are disengaged. The planetary carrier 14 is fixed to the housing 41 through brake Q11. Power is transmitted from the sun gear 23 to the ring gear 24. At this time, the rotation direction of the ring gear 24 is opposite to that of the sun gear 23. Clutch D17 drives the clutch housing 22 to rotate, and power is then transmitted from the clutch housing 22 to the vehicle power output shaft 20, which ultimately drives the vehicle drive flange 19 to rotate.

[0075] Figure 5The hydraulic power transmission route of the first stage of this invention is as follows: Power is output from the rotor of the drive motor 37 to the second power input shaft 36. Clutch C35 is engaged, and the power is transmitted to the hydraulic pump input shaft 34 through the driving and driven ends of clutch C35. After being driven, the hydraulic pump 33 converts mechanical energy into hydraulic energy, generating high-pressure hydraulic oil. This high-pressure hydraulic oil enters the hydraulic motor 31 through the hydraulic pipe 32, driving the hydraulic motor 31 to rotate forward and converting hydraulic energy into mechanical energy, ultimately driving the hydraulic power input shaft 30 to rotate. Gear C2 29 rotates with the hydraulic power input shaft 30, and the power is transmitted to gear B2 8 through gear meshing. At this time, the sliding sleeve 10 is in the left position, and its inner spline meshes with the splined hub 28 and the outer spline of gear B2 8 simultaneously. Power is transmitted from the sliding sleeve 10 to the splined hub 28 through gear B2 8, and the splined hub 28 drives the planetary carrier 14 to rotate. The planetary carrier 14 drives the intermediate third shaft 21 to rotate, the clutch F18 engages, and the power is transmitted from the intermediate third shaft 21 to the vehicle power output shaft 20 through the clutch F18, which ultimately drives the vehicle drive flange 19 to rotate.

[0076] Figure 6 The hydraulic two-stage power transmission route of this invention is as follows: Power is output from the rotor of the drive motor 37 to the second power input shaft 36. Clutch C35 is engaged, and the power is transmitted to the hydraulic pump input shaft 34 through the driving and driven ends of clutch C35. After being driven, the hydraulic pump 33 converts mechanical energy into hydraulic energy, generating high-pressure hydraulic oil. This high-pressure hydraulic oil enters the hydraulic motor 31 through the hydraulic pipe 32, driving the hydraulic motor 31 to rotate forward and converting hydraulic energy into mechanical energy, ultimately driving the hydraulic power input shaft 30 to rotate. Gear C3 27 rotates with the hydraulic power input shaft 30, and gear C3 27 transmits power to gear B3 26 through gear meshing. At this time, the sliding sleeve 10 is in the right position, and its inner spline meshes with the splined hub 28 and the outer spline of gear B3 26 simultaneously. Power is transmitted from the sliding sleeve 10 to the splined hub 28 through gear B3 26, and the splined hub 28 drives the planetary carrier 14 to rotate. The planetary carrier 14 drives the intermediate third shaft 21 to rotate, the clutch F18 engages, and the power is transmitted from the intermediate third shaft 21 to the vehicle power output shaft 20 through the clutch F18, which ultimately drives the vehicle drive flange 19 to rotate.

[0077] Figure 7The power transmission route for the hydraulic reversing section of this invention is as follows: Power is output from the rotor of the drive motor 37 to the second power input shaft 36. Clutch C35 engages, and the power is transmitted through the driving and driven ends of clutch C35 to the hydraulic pump input shaft 34. The hydraulic pump 33, once driven, converts mechanical energy into hydraulic energy, generating high-pressure hydraulic oil. This high-pressure hydraulic oil enters the hydraulic motor 31 via the hydraulic pipe 32, driving the hydraulic motor 31 to rotate in the opposite direction and converting hydraulic energy back into mechanical energy, ultimately causing the hydraulic power input shaft 30 to rotate in the opposite direction. Gear C2 29 follows the hydraulic power input shaft 30 in the opposite direction, and gear C2 29 transmits power to gear B2 8 through gear meshing. At this time, the sliding sleeve 10 is in the left position, and its inner spline meshes simultaneously with the splined hub 28 and the outer spline of gear B2 8. Power is transmitted through the sliding sleeve 10 from gear B2 8 to the splined hub 28, which drives the planetary carrier 14 to rotate in the opposite direction. The planetary carrier 14 drives the intermediate third shaft 21 to rotate in the opposite direction. The clutch F18 is engaged, and the power is transmitted from the intermediate third shaft 21 to the vehicle power output shaft 20 through the clutch F18, which ultimately drives the vehicle drive flange 19 to rotate in the opposite direction.

[0078] Figure 7 The specific power transmission route for the hydraulic reversing mechanism of this invention is as follows: Power is output from the rotor of the drive motor 37 to the second power input shaft 36. Clutch C35 engages, and the power is transmitted through the driving and driven ends of clutch C35 to the hydraulic pump input shaft 34. The hydraulic pump 33, once driven, converts mechanical energy into hydraulic energy, generating high-pressure hydraulic oil. This high-pressure hydraulic oil enters the hydraulic motor 31 via the hydraulic pipe 32, driving the hydraulic motor 31 to rotate in the opposite direction and converting hydraulic energy back into mechanical energy, ultimately causing the hydraulic power input shaft 30 to rotate in the opposite direction. Gear C3 27 follows the hydraulic power input shaft 30 in the opposite direction, and gear C3 27 transmits power to gear B3 26 through gear meshing. At this time, the sliding sleeve 10 is in the right position, and its inner spline meshes simultaneously with the splined hub 28 and the outer spline of gear B3 26. Power is transmitted through the sliding sleeve 10 from gear B3 26 to the splined hub 28, which drives the planetary carrier 14 to rotate in the opposite direction. The planetary carrier 14 drives the intermediate third shaft 21 to rotate in the opposite direction. The clutch F18 is engaged, and the power is transmitted from the intermediate third shaft 21 to the vehicle power output shaft 20 through the clutch F18, which ultimately drives the vehicle drive flange 19 to rotate in the opposite direction.

[0079] Figure 8The specific power transmission route of the hybrid single-stage transmission of this invention is as follows: First power is output from the rotor of the drive motor 37 to the second power input shaft 36. Gear C1 38 transmits power to gear B1 40 through gear meshing, and gear B1 40 drives the intermediate first shaft 4 to rotate. Clutch B6 engages, and power is transmitted from the intermediate first shaft 4 to the intermediate second shaft 9 through the driving and driven ends of clutch B6. The sun gear 23 rotates with the intermediate second shaft 9. Second power is output from the rotor of the drive motor 37 to the second power input shaft 36. Clutch C35 engages, and power is transmitted to the hydraulic pump input shaft 34 through the driving and driven ends of clutch C35. After being driven, the hydraulic pump 33 converts mechanical energy into hydraulic energy, generating high-pressure hydraulic oil. This high-pressure hydraulic oil enters the hydraulic motor 31 through the hydraulic pipe 32, driving the hydraulic motor 31 to rotate forward and converting hydraulic energy into mechanical energy, ultimately driving the hydraulic power input shaft 30 to rotate. Gear C2 29 rotates with the hydraulic power input shaft 30, and gear C2 29 transmits power to gear B2 8 through gear meshing. At this time, the sliding sleeve 10 is in the left position. The inner spline of the sliding sleeve 10 meshes simultaneously with the outer spline of the splined hub 28 and gear B28. Power is transmitted through the sliding sleeve 10 to the splined hub 28 via gear B28, and the splined hub 28 drives the planetary carrier 14 to rotate. At the planetary gear set, the first and second power are coupled. At this time, brakes Q11 and E12 and clutch W13 are all in the disengaged state. The coupled power driven by the sun gear 23 and planetary carrier 14 is output to the ring gear 24. At this time, clutch D17 is engaged, and the power of the ring gear 24 is transmitted through clutch D17 to the vehicle's power output shaft 20, which ultimately drives the vehicle's drive flange 19 to rotate.

[0080] Figure 9The hybrid two-stage power transmission route of this invention is as follows: First, the first power is output from the rotor of the drive motor 37 to the second power input shaft 36. Gear C1 38 transmits the power to gear B1 40 through gear meshing, and gear B1 40 drives the intermediate first shaft 4 to rotate. Clutch B6 engages, and the power is transmitted from the intermediate first shaft 4 to the intermediate second shaft 9 through the driving and driven ends of clutch B6. The sun gear 23 rotates with the intermediate second shaft 9. Second, the second power is output from the rotor of the drive motor 37 to the second power input shaft 36. Clutch C35 engages, and the power is transmitted to the hydraulic pump input shaft 34 through the driving and driven ends of clutch C35. After being driven, the hydraulic pump 33 converts mechanical energy into hydraulic energy, generating high-pressure hydraulic oil. This high-pressure hydraulic oil enters the hydraulic motor 31 through the hydraulic pipe 32, driving the hydraulic motor 31 to rotate forward and convert hydraulic energy into mechanical energy, ultimately driving the hydraulic power input shaft 30 to rotate. Gear C3 27 rotates with the hydraulic power input shaft 30, and transmits power to gear B3 26 through gear meshing. At this time, the sliding sleeve 10 is in the right position, and the inner spline of the sliding sleeve 10 meshes with the splined hub 28 and the outer spline of gear B3 26 simultaneously. Power is transmitted from the sliding sleeve 10 to the splined hub 28 via gear B3 26, and the splined hub 28 drives the planetary carrier 14 to rotate. At the planetary gear set, the first and second power are coupled. At this time, brakes Q11 and E12 and clutch W13 are all in the disengaged state, and the coupled power driven by the sun gear 23 and the planetary carrier 14 is output to the ring gear 24. At this time, clutch D17 is engaged, and the power of the ring gear 24 is transmitted to the vehicle power output shaft 20 via clutch D17, ultimately driving the vehicle drive flange 19 to rotate.

[0081] Figure 10The power transmission route for the first stage of the hybrid reversing mechanism of this invention is as follows: First, the power is output from the rotor of the drive motor 37 to the second power input shaft 36. Gear C1 38 transmits the power to gear B1 40 through gear meshing, and gear B1 40 drives the intermediate first shaft 4 to rotate. Clutch B6 engages, and the power is transmitted from the intermediate first shaft 4 to the intermediate second shaft 9 through the driving and driven ends of clutch B6. The sun gear 23 rotates with the intermediate second shaft 9. Second, the power is output from the rotor of the drive motor 37 to the second power input shaft 36. Clutch C35 engages, and the power is transmitted through the driving and driven ends of clutch C35 to the hydraulic pump input shaft 34. After being driven, the hydraulic pump 33 converts mechanical energy into hydraulic energy, generating high-pressure hydraulic oil. This high-pressure hydraulic oil enters the hydraulic motor 31 through the hydraulic pipe 32, driving the hydraulic motor 31 to rotate in the opposite direction and converting hydraulic energy into mechanical energy, ultimately driving the hydraulic power input shaft 30 to rotate in the opposite direction. Gear C2 29 rotates in the opposite direction following the hydraulic power input shaft 30, and transmits power to gear B2 8 through gear meshing. At this time, the sliding sleeve 10 is in the left position, and the inner spline of the sliding sleeve 10 meshes with the splined hub 28 and the outer spline of gear B2 8 simultaneously. Power is transmitted from gear B2 8 to the splined hub 28 through the sliding sleeve 10, and the splined hub 28 drives the planetary carrier 14 to rotate in the opposite direction. At the planetary gear set, the first power and the second power are coupled. At this time, brake Q11, brake E12 and clutch W13 are all in the disengaged state, and the coupled power driven by the sun gear 23 and the planetary carrier 14 is output to the ring gear 24. At this time, clutch D17 is engaged, and the power of the ring gear 24 is transmitted to the vehicle power output shaft 20 through clutch D17, which ultimately drives the vehicle drive flange 19 to rotate in the opposite direction.

[0082] Figure 11The specific power transmission route for the hybrid reversing mechanism of this invention is as follows: First, the first power is output from the rotor of the drive motor 37 to the second power input shaft 36. Gear C1 38 transmits the power to gear B1 40 through gear meshing, and gear B1 40 drives the intermediate first shaft 4 to rotate. Clutch B6 engages, and the power is transmitted from the intermediate first shaft 4 to the intermediate second shaft 9 through the driving and driven ends of clutch B6. The sun gear 23 rotates with the intermediate second shaft 9. Second, the second power is output from the rotor of the drive motor 37 to the second power input shaft 36. Clutch C35 engages, and the power is transmitted to the hydraulic pump input shaft 34 through the driving and driven ends of clutch C35. After being driven, the hydraulic pump 33 converts mechanical energy into hydraulic energy, generating high-pressure hydraulic oil. This high-pressure hydraulic oil enters the hydraulic motor 31 through the hydraulic pipe 32, driving the hydraulic motor 31 to rotate in the opposite direction and converting hydraulic energy into mechanical energy, ultimately driving the hydraulic power input shaft 30 to rotate in the opposite direction. Gear C3 27 rotates in the opposite direction following the hydraulic power input shaft 30, and transmits power to gear B3 26 through gear meshing. At this time, the sliding sleeve 10 is in the right position, and the inner spline of the sliding sleeve 10 meshes with the splined hub 28 and the outer spline of gear B3 26 simultaneously. Power is transmitted from gear B3 26 to the splined hub 28 through the sliding sleeve 10, and the splined hub 28 drives the planetary carrier 14 to rotate in the opposite direction. At the planetary gear set, the first power and the second power are coupled. At this time, brake Q11, brake E12 and clutch W13 are all in the disengaged state, and the coupled power driven by the sun gear 23 and the planetary carrier 14 is output to the ring gear 24. At this time, clutch D17 is engaged, and the power of the ring gear 24 is transmitted to the vehicle power output shaft 20 through clutch D17, which ultimately drives the vehicle drive flange 19 to rotate in the opposite direction.

[0083] A control method for a range-extended agricultural hybrid transmission includes: vehicle energy management and range-extending control, multi-source power operation mode switching control, PTO and travel speed decoupling control, and active synchronous shifting control of adjacent continuously variable transmission segments.

[0084] The vehicle energy management and range extension control include a pure electric priority mode and a range extension and driving charging mode. The vehicle controller obtains the state of charge of the power battery 40 in real time and the vehicle's required power based on the accelerator pedal opening. It then automatically switches between operating modes according to the set energy management strategy. The pure electric priority drive mode control strategy is as follows: when the state of charge of the power battery 40 is greater than the preset high charge threshold and the vehicle's required power is less than the preset pure electric working power threshold, the vehicle controller controls the engine 1 to be in a stopped state. At this time, the system enters the pure electric drive mode, where the power battery 40 alone supplies power to the drive motor 37. The drive motor 37 outputs all driving power to the second power input shaft 37 through the rotor, achieving zero-emission and low-noise operation of the tractor under low-load or light-load transfer conditions. The range-extending and driving charging mode control strategy is as follows: When the state of charge of the power battery 40 is determined to be lower than the preset low charge threshold, or the vehicle's required power is greater than or equal to the pure electric operating power threshold (such as encountering heavy-load plowing, climbing, or other working conditions), the vehicle controller system enters the range-extending mode. Specifically, this includes power distribution and energy balance mechanisms. The vehicle controller controls the engine 1 to ignite and start, and makes it run in the highest fuel-efficient speed range. The power of the engine 1 directly drives the rotor of the generator 3 to rotate and generate electricity through the engine output shaft 2. The electrical energy output by the generator 3 is preferentially supplied to the drive motor 37 to meet the vehicle's driving needs under the current heavy-load working conditions. If the output power of the generator 3 is greater than the vehicle's required power, the vehicle controller controls the excess electrical energy to charge the power battery 40 for driving charging. If the output power of the generator 3 is less than the vehicle's required power, the vehicle controller controls the power battery 40 and the generator 3 to jointly provide electrical energy to the drive motor 37, realizing dual-source parallel power supply to output maximum torque.

[0085] Among them, the multi-source power operation mode switching control includes: pure hydraulic low-speed micro-motion and starting mode, electro-mechanical-hydraulic hybrid continuously variable speed mode, and pure mechanical high-speed transfer mode. During the vehicle driving and operation process, the vehicle controller real-time collects the current vehicle speed v and the accelerator pedal opening signal, and compares the current vehicle speed v with the preset first vehicle speed threshold v1 and the second vehicle speed threshold v2 in real time (where v1 < v2), so as to automatically execute the switching control of the following power modes. The control strategy of the pure hydraulic low-speed micro-motion and starting mode is as follows. When it is judged that the current vehicle speed v < v1 and a vehicle starting or heavy-load micro-motion command is received, the vehicle controller controls the system to enter the pure hydraulic drive mode. The specific actions are as follows: the vehicle controller controls the clutch C36 to engage, controls the sliding sleeve 10 to be in the left position (or right position), and at the same time controls the clutch F17 to engage, and the rest of the clutches and brakes remain disengaged; at this time, the mechanical power of the drive motor 37 is cut off by the clutch B6, and all the power is converted into hydraulic energy by the hydraulic pump 34, and then output to the planet carrier 14 through the hydraulic motor 32, and finally output outward by the clutch F17. This mode utilizes the physical characteristics of hydraulic transmission with low speed and large torque and allowing long-time slip to achieve a smooth and non-impact start of the tractor under heavy-load implements. The control strategy of the electro-mechanical-hydraulic hybrid continuously variable speed mode is as follows. When it is judged that v1 ≤ v ≤ v2 and the vehicle is in a continuous operation condition, the vehicle controller controls the system to enter the electro-mechanical-hydraulic hybrid continuously variable speed mode. The specific actions are as follows: taking the first hybrid stage as an example, the vehicle controller controls the clutch B6 and the clutch C36 to engage simultaneously, controls the sliding sleeve 10 to be in the corresponding working position, and controls the clutch D16 to engage, and at the same time ensures that the brake Q11, the brake E12 and the clutch W13 are all in the disengaged state; the mechanical power output by the drive motor 37 is input to the sun gear 23, and the hydraulic power converted by the hydraulic system is input to the planet carrier 14. After the two-way power is deeply coupled without interference in the planetary gear set, it is uniformly output by the ring gear 24; the vehicle controller realizes the smooth and continuous adjustment of the field operation vehicle speed by changing the displacement of the hydraulic pump 34 in real time. The control strategy of the pure mechanical high-speed transfer mode is as follows. When it is judged that the current vehicle speed v > v2 and the vehicle is in a low-load cruise or transfer condition on the road, the vehicle controller controls the system to enter the pure mechanical direct drive or deceleration mode. The specific actions are as follows: taking the first mechanical gear as an example, the vehicle controller controls the clutch B6 to engage, controls the brake E12 to engage to fix the ring gear 24, and at the same time controls the clutch F17 to engage and output outward, and controls the clutch C36 to disengage to physically cut off the power input of the hydraulic circuit; in this mode, the system completely eliminates the inherent volumetric efficiency loss of hydraulic transmission, and the vehicle power is only transmitted through the high-efficiency gear mechanical path, thereby greatly reducing the vehicle energy consumption of the tractor during high-speed transfer.

[0086] The active synchronous shift control process for adjacent continuously variable transmission (CVT) segments includes: shift prediction and speed difference calculation, hydraulic active synchronization adjustment, and flexible switching with low speed difference. In the electromechanical-hydraulic hybrid CVT mode, when the vehicle controller determines that a shift between adjacent segments is necessary based on the current vehicle speed, accelerator pedal opening, and load changes, the vehicle controller executes the following strategy to avoid power interruption and mechanical shock. The shift prediction and speed difference calculation process is as follows: Before executing the shift action, the vehicle controller maintains the clutch of the current working segment in an engaged state to maintain power output; simultaneously, the vehicle controller uses the speed sensors of each axle to collect the speeds of the driving and driven ends of the target clutch that is about to engage in real time, and calculates the speed difference between the driving and driven ends in real time. The hydraulic active synchronization adjustment process is as follows: Based on the calculated speed difference, the vehicle controller sends an active adjustment command to the hydraulic pump 34, continuously and steplessly changing the displacement of the hydraulic pump 34. The change in the displacement of the hydraulic pump 34 causes the output speed of the hydraulic motor 32 to change precisely accordingly. Then, through the coupling effect of the transmission gear and the planetary gear set, it actively adjusts and forcibly causes the speed difference between the active and driven ends of the target shift actuator to gradually decrease and approach zero. The low speed difference flexible switching process is as follows: When the vehicle controller detects that the absolute value of the speed difference between the active and driven ends is less than the preset safety synchronization threshold, it determines that the system has reached the synchronization state. At this time, the vehicle controller immediately issues a command to control the engagement of the target shift actuator and simultaneously controls the disengagement of the clutch in the original working segment.

[0087] The decoupling control process between PTO and travel speed is as follows: engine and PTO constant speed locking, power splitting and energy balance, and independent stepless adjustment of travel speed. When the vehicle is in agricultural operation conditions requiring stable power output, such as combine harvesting or rotary tillage, the vehicle controller receives and responds to the PTO constant speed operation command and executes the following decoupling control strategy. The engine and PTO constant speed locking process is as follows: the vehicle controller calculates the target engine speed based on the rated working speed requirement of the mounted implements; the vehicle controller controls the engine 1 to start and locks its output speed within the most efficient working range of the target engine speed; simultaneously, the vehicle controller controls the clutch A7 to engage, and the mechanical power of the engine 1 is transmitted at a constant speed to the PTO power output shaft 15 through the engine output shaft 2 and the first power input shaft 5 via the engaged clutch A7, so as to ensure that the speed of the PTO power output flange 16 is constant and not affected by the vehicle's driving state. The power splitting and energy balancing process is as follows: When engine 1 is running at a constant speed, its output mechanical power is physically split: the first part of the power is used to meet the working load requirements of the PTO power output shaft 15; the second part of the surplus power drives the rotor of generator 3 to rotate and generate electricity; the electrical energy output by generator 3 is distributed in real time to drive motor 37 or charged into power battery 40 by vehicle controller according to energy management strategy. The independent stepless adjustment process of travel speed is as follows: while maintaining the constant speed operation of PTO power output shaft 15, vehicle controller collects accelerator pedal displacement signal and current vehicle speed signal in real time to obtain target travel speed; based on the target travel speed, vehicle controller independently sends torque and speed commands to drive motor 37 and simultaneously adjusts the displacement of hydraulic pump 34; the actual travel speed of the vehicle is completely determined by the speed of drive motor 37 and the transmission ratio of hydraulic system.

[0088] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A range-extended agricultural hybrid transmission, characterized in that, It includes a housing and a first transmission system, a second transmission system, and a third transmission system sequentially disposed therein; The first transmission system includes: an engine connected to an engine output shaft; a generator whose rotor is connected at one end to the engine output shaft and at the other end to a first power input shaft; a first power input shaft connected to a PTO power output shaft via the driving and driven ends of a clutch A; and a PTO power output flange connected to the PTO power output shaft. The second transmission system includes: a power battery, which is electrically connected to a drive motor and a generator respectively; a drive motor, which is connected to a second power input shaft; a gear C1 connected to one end of the second power input shaft and a hydraulic pump input shaft connected to the other end; a hydraulic pump, which is connected to a hydraulic motor through a hydraulic pipe; and a hydraulic motor, which is connected to a hydraulic power input shaft. The third transmission system includes: a first intermediate shaft with gear B1 mounted thereon, gear B1 meshing with gear C1; a second intermediate shaft connected to the first intermediate shaft via clutch B; a planetary gear set assembly including a sun gear, planet gears, a planet carrier, and a ring gear, the sun gear being fixed on the second intermediate shaft, the planet gears being pivotally connected to the planet carrier and meshing with the sun gear and the ring gear respectively; the planet carrier being connected to the hydraulic power input shaft via a gear switching mechanism including a sliding sleeve; a third intermediate shaft connected to the planet carrier; and a vehicle power output shaft connected to the ring gear or the third intermediate shaft, one end of which is fixed with a vehicle drive flange.

2. The range-extended agricultural hybrid transmission according to claim 1, characterized in that, The first power input shaft is connected to the PTO power output shaft via the driving and driven ends of clutch A; the second power input shaft is connected to the hydraulic pump input shaft via the driving and driven ends of clutch C; the intermediate first shaft is connected to the intermediate second shaft via the driving and driven ends of clutch B; the planetary carrier is fixedly connected to the housing via brake Q; the gear ring is fixedly connected to the housing via brake E, and the gear ring is connected to the planetary carrier via the driving and driven ends of clutch W; the gear ring is connected to the vehicle power output shaft via the driving and driven ends of clutch D and the clutch housing; the intermediate third shaft is connected to the vehicle power output shaft via the driving and driven ends of clutch F and the clutch housing.

3. The range-extended agricultural hybrid transmission according to claim 1, characterized in that, The planetary carrier is connected to the hydraulic power input shaft via a gear switching mechanism. The gear switching mechanism includes gears B2 and B3 loosely fitted on the planetary carrier, a splined hub fixedly connected to the planetary carrier, and a sliding sleeve slidably connected to the splined hub via an internal spline. Gears C2 and C3 are fixedly mounted on the hydraulic power input shaft. Gears B2 and C2 are always meshed, and gears B3 and C3 are always meshed. The sliding sleeve can slide along the axial direction of the splined hub, selectively engaging with either gear B2 or gear B3, thereby transmitting different transmission ratios of the power from the hydraulic power input shaft to the planetary carrier.

4. A control method for a range-extended agricultural hybrid transmission, applied to the range-extended agricultural hybrid transmission according to any one of claims 1-3, characterized in that, Includes the following steps: Vehicle energy management and range extender control steps; Multi-source power operation mode switching control steps; Active synchronization switching control steps for adjacent continuously variable transmission (CVT) segments; PTO and walking speed decoupling control steps.

5. The control method for a range-extended agricultural hybrid transmission according to claim 4, characterized in that, The vehicle energy management and range extension control steps specifically include: The vehicle controller acquires the state of charge of the power battery and analyzes the vehicle's required power in real time. When it is determined that the state of charge of the power battery is greater than the preset high power threshold and the vehicle demand power is less than the preset pure electric operating power threshold, the engine is controlled to stop, and the system enters the pure electric priority drive mode, where the power battery supplies power to the drive motor alone; When it is determined that the state of charge of the power battery is lower than the preset low power threshold, or the vehicle demand power is greater than or equal to the pure electric operating power threshold, the engine is controlled to start, and the system enters the range extender and vehicle charging mode, where the engine drives the generator to generate electricity; if the output power of the generator is greater than the vehicle demand power, the excess electrical energy is controlled to be charged into the power battery; if the output power of the generator is less than the vehicle demand power, the power battery and the generator are controlled to jointly supply power to the drive motor.

6. The control method for a range-extended agricultural hybrid transmission according to claim 4, characterized in that, The multi-source power operation mode switching control steps specifically include: The vehicle controller continuously collects the current vehicle speed v and the target load signal, and compares them with the preset first vehicle speed threshold v1 and second vehicle speed threshold v2, where v1 < v2; When v < v1 and a start or fine movement command is received, the control system enters the pure hydraulic low-speed fine movement and start mode: the mechanical power transmission from the drive motor to the planetary gear set is cut off, and the power is only transmitted to the planet carrier through the hydraulic pump and hydraulic motor and output outward; When v1 ≤ v ≤ v2 and the vehicle is in a continuous operation condition, the control system enters the electro-hydraulic-mechanical hybrid continuously variable speed mode: the mechanical power output by the drive motor is input to the sun gear, and the hydraulic power output by the hydraulic system is input to the planet carrier. The two-way power is coupled in the planetary gear set and uniformly output by the ring gear. The vehicle controller realizes continuously variable speed by adjusting the displacement of the hydraulic pump in real time to change the speed of the planet carrier; When v > v2 and the vehicle is in a low-load cruise or transfer condition, the control system enters the pure mechanical high-speed transfer mode: the power input of the hydraulic circuit is separated and the ring gear is fixed, and the power is only transmitted to the intermediate third shaft through mechanical gears and output outward.

7. The control method for a range-extended agricultural hybrid transmission according to claim 4, characterized in that, The active synchronous section change control steps for adjacent continuously variable speed sections specifically include: When switching between adjacent sections in the electro-hydraulic-mechanical hybrid continuously variable speed mode, perform section change prediction and speed difference calculation: maintain the engagement of the actuator in the current working section, continuously collect the speeds of the active and driven ends of the target actuator to be engaged, and calculate the speed difference between the active and driven ends; Perform hydraulic active synchronous adjustment: according to the speed difference, continuously and infinitely change the displacement of the hydraulic pump to make the speed difference between the active and driven ends of the target actuator approach zero; Perform low-speed difference flexible switching: when the absolute value of the speed difference is less than the preset safe synchronous threshold, control the target actuator to engage and simultaneously disengage the actuator in the original working section.

8. The control method for a range-extended agricultural hybrid transmission according to claim 4, characterized in that, The PTO and travel speed decoupling control steps specifically include: When receiving and responding to the PTO constant speed operation command, perform engine and PTO constant speed locking: the vehicle controller controls the engine to start and lock at the target constant speed, and at the same time controls the power of the engine to be constantly transmitted to the PTO power output shaft; Power splitting and energy balancing: The mechanical power output of the engine is physically split. The first part satisfies the load of the PTO power output shaft, and the second part of the surplus power drives the generator to generate electricity. The electrical energy is distributed to the drive motor or charged into the power battery by the vehicle controller. Independent stepless adjustment of walking speed: While maintaining the constant speed of the PTO power output shaft, the vehicle controller independently sends torque and speed commands to the drive motor according to the target driving speed, and simultaneously adjusts the displacement of the hydraulic pump, so that the actual walking speed of the vehicle is determined by the speed of the drive motor and the transmission ratio of the hydraulic system, and is completely decoupled from the engine speed.

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