A range extended power device and a control method thereof

Abstract

A range-extended power unit and its control method are disclosed, relating to the field of new energy construction machinery technology. The unit includes an engine, a generator, a drive motor, a first-gear transmission mechanism, a second-gear transmission mechanism, a hydraulic shift mechanism, and a power output mechanism (PTO). This range-extended power unit employs a method of mechanically connecting the engine and generator, coaxially connecting the generator and drive motor, and selectively connecting the drive motor to either the first-gear or second-gear transmission mechanism via the hydraulic shift mechanism. Furthermore, the second-gear transmission mechanism simultaneously connects to both the travel mechanism and the PTO. This achieves complete decoupling of the PTO speed from the vehicle speed and continuously variable transmission (CVT), simplifying driver operation, improving field work quality, and reducing overall fuel consumption.

Description

Technical Field

[0001] This invention relates to the field of new energy engineering machinery technology, and more specifically, to a range-extended power unit and its control method. Background Technology

[0002] Currently, in the field of agricultural machinery, tractors, as the main power platform, generally adopt a mechanical multi-speed gearbox combined with a dry clutch structure for their power transmission systems. This traditional transmission scheme has the following technical problems: 1) Complex operation: It requires frequent manual gear shifting, which requires a high level of driver experience and results in low work efficiency.

[0003] 2) PTO speed is coupled with vehicle speed: The PTO speed changes with the vehicle speed and cannot be adjusted independently, resulting in unstable quality of rotary tillage, sowing and other operations.

[0004] 3) Poor fuel economy: The engine is difficult to always operate in the optimal fuel consumption range, especially under partial load conditions, resulting in significant fuel waste.

[0005] 4) Power interruption during gear shifting: Power must be cut off when shifting gears with a dry clutch, which affects the quality of continuous operation.

[0006] 5) Lack of continuously variable transmission (CVT) capability: Fixed gears cannot finely adjust vehicle speed, resulting in insufficient adaptability.

[0007] Although the series range extender solutions that have emerged in recent years can achieve continuously variable transmission, PTO requires two conversions of "mechanical → electrical energy → mechanical" under heavy load, resulting in significant energy loss. Furthermore, high-power electric drives are expensive and fail to meet the high-efficiency requirements of direct drive for agricultural machinery POT.

[0008] Therefore, there is an urgent need for a new type of power unit that can retain the advantages of continuously variable transmission and easy operation, while achieving efficient direct drive of PTO and speed decoupling at low cost. Summary of the Invention

[0009] The purpose of this invention is to provide a range-extended power unit and its control method to solve the problems of complex operation of traditional tractor mechanical multi-speed gearboxes, unstable work quality caused by PTO speed coupling with vehicle speed, power interruption during gear shifting, and poor fuel economy.

[0010] The embodiments of the present invention are implemented as follows: A range-extended power unit, comprising: Engine, generator, drive motor, first gear transmission mechanism, second gear transmission mechanism, hydraulic shift mechanism, and output mechanism PTO; The engine's output shaft is mechanically connected to the generator's rotor shaft; The rotor shaft of the generator is coaxially connected to the rotor shaft of the drive motor; The output of the drive motor can be selectively connected to a first-gear transmission mechanism or a second-gear transmission mechanism via a hydraulic shifting mechanism. The output end of the first gear transmission mechanism is connected to the vehicle's running gear. The second-gear transmission mechanism has two output ends: one output end is connected to the vehicle running gear, and the other output end is connected to the output mechanism PTO.

[0011] Furthermore, in other preferred embodiments of the present invention, a gear position controller is also included, which is controlled and connected to the hydraulic shift mechanism, for receiving shift commands from the vehicle controller and controlling the operation of the hydraulic shift mechanism.

[0012] Furthermore, in other preferred embodiments of the present invention, a dual-motor controller is also included. The dual-motor controller is electrically connected to the generator and the drive motor respectively, and is used to adjust the working state of the generator and the drive motor respectively according to the torque command of the vehicle controller.

[0013] Furthermore, in other preferred embodiments of the present invention, a range extender controller and an engine controller are also included. The range extender controller is communicatively connected to the vehicle controller and the engine controller and is used to adjust the operating point of the engine according to the energy distribution command of the vehicle controller.

[0014] Furthermore, in other preferred embodiments of the present invention, the hydraulic shifting mechanism is a wet clutch or a hydraulic coupling, used for smooth switching between the first gear transmission mechanism and the second gear transmission mechanism without power interruption.

[0015] A control method for the above-mentioned range-extended power unit includes the following steps: S1. Obtain the current working status of the vehicle, including whether the output mechanism PTO is in working condition; S2. When the output mechanism PTO is not working, the hydraulic shift mechanism is controlled to engage the first gear transmission mechanism. At this time, the engine drives the generator to generate electricity, and the generated electricity supplies the drive motor to drive the vehicle. S3. When the output mechanism PTO is working, the hydraulic shift mechanism is controlled to engage the second gear transmission mechanism. At this time, part of the engine's mechanical power directly drives the output mechanism PTO through the second gear transmission mechanism, and the other part of the mechanical power is converted into electrical energy by the generator and supplied to the drive motor to drive the vehicle.

[0016] Furthermore, in other preferred embodiments of the present invention, in step S2, one of the following four operating modes is selected and executed based on the battery SOC value and the required driving power: Pure electric drive mode: When the SOC is higher than the first threshold and the drive power demand is lower than the preset value, the drive motor is driven only by the battery, and the engine and generator stop working; Power Follower Mode: When the State of Charge (SOC) is in the middle range, the engine adjusts its output power in real time according to the driving power demand, so that the electrical energy generated by the generator just meets the needs of the drive motor. Driving charging mode: When the SOC is below the second threshold, the engine runs at its most efficient point, and the excess electrical energy is charged into the battery; Power Enhancement Mode: When the drive power demand exceeds the engine's maximum power output, the battery and generator work together to supply power to the drive motor.

[0017] Furthermore, in other preferred embodiments of the present invention, in step S3, the total output power of the engine is dynamically adjusted according to the power required by the PTO, so that the sum of the mechanical power allocated to the output mechanism PTO and the mechanical power allocated to the generator is equal to the actual output power of the engine.

[0018] Furthermore, in other preferred embodiments of the present invention, when the hydraulic shifting mechanism is switching, it compensates for the power interruption during the switching process by temporarily adjusting the torque of the drive motor, thereby achieving shock-free shifting.

[0019] Furthermore, in other preferred embodiments of the present invention, when the output mechanism PTO switches from the working state to the non-working state, the mechanical power allocated by the engine to the output mechanism PTO is first reduced to zero, and then the action of engaging the first gear transmission mechanism in step S2 is executed.

[0020] The beneficial effects of the embodiments of the present invention are: This invention provides a range-extended power unit and its control method, which has at least the following beneficial effects: (1) Decoupling of PTO speed and vehicle speed: PTO speed can be adjusted independently, and the quality of operations such as rotary tillage and sowing is not affected by vehicle speed fluctuations, significantly improving the consistency of operations.

[0021] (2) Stepless speed regulation, easy operation: The drive motor achieves stepless speed regulation throughout the entire process, and the two-speed transmission covers low-speed traction and high-speed transportation conditions. There is no need to frequently change gears manually, which reduces labor intensity.

[0022] (3) PTO has high efficiency in heavy-duty operation: When PTO is working, the mechanical power of the engine directly drives PTO, avoiding the energy loss of two conversions of "mechanical → electrical energy → mechanical", which is suitable for long-term heavy-duty operations such as deep plowing and rotary tillage.

[0023] (4) Reduced fuel consumption: The engine always operates in the optimal economic zone, and with the intelligent switching of multiple modes, the overall fuel consumption is significantly lower than that of traditional mechanical transmission tractors.

[0024] (5) Smooth and uninterrupted gear shifting: The hydraulic shifting mechanism, in conjunction with the torque compensation of the drive motor, achieves smooth gear shifting without impact, ensuring the quality of continuous operation. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a range-extended power unit provided in an embodiment of the present invention.

[0027] Icons: 1-Engine; 2-Generator; 3-Drive motor; 4-First gear transmission mechanism; 5-Second gear transmission mechanism; 6-Hydraulic shift mechanism; 7-Output mechanism PTO; 8-Gear position controller; 9-Vehicle controller; 10-Dual motor controller; 11-Range extender controller; 12-Engine controller. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. Example

[0033] This embodiment provides a range-extended power unit, referring to... Figure 1 As shown, it includes an engine 1, a generator 2, a drive motor 3, a first gear transmission mechanism 4, a second gear transmission mechanism 5, a hydraulic shifting mechanism 6, and an output mechanism PTO 7.

[0034] Among them, such as Figure 1 As shown, the output shaft of engine 1 is mechanically connected to the rotor shaft of generator 2; the rotor shaft of generator 2 is coaxially connected to the rotor shaft of drive motor 3. Through the coaxial series connection of engine 1, generator 2, and drive motor 3, engine 1 drives generator 2 to generate electricity, which supplies the drive motor 3, directly driving the wheels. Since drive motor 3 itself has continuously variable speed control, the vehicle can achieve continuously variable transmission throughout the entire range, eliminating the need for a traditional multi-speed gearbox and simplifying operation.

[0035] The output of drive motor 3 can be selectively connected to either first-gear transmission mechanism 4 or second-gear transmission mechanism 5 via hydraulic shifting mechanism 6. The output of first-gear transmission mechanism 4 is connected to the vehicle's traveling mechanism. Second-gear transmission mechanism 5 has two outputs: one connected to the vehicle's traveling mechanism and the other connected to output mechanism PTO 7. The hydraulic shifting mechanism 6 allows for smooth switching between the two gears, achieving two different transmission ratios. One output of second-gear transmission mechanism 5 drives the wheels, and the other drives the PTO. This allows the PTO to be directly driven by the mechanical power of engine 1, independent of the speed of drive motor 3, thus achieving complete decoupling of PTO speed from vehicle speed—the PTO can operate independently at the optimal speed for the implement, unaffected by vehicle speed fluctuations, improving work quality.

[0036] Furthermore, such as Figure 1 As shown, the range-extended power unit also includes a gear position controller 8, which is connected to the hydraulic shift mechanism 6 for receiving shift commands from the vehicle controller 9 and controlling the operation of the hydraulic shift mechanism 6. The gear position controller 8 automates the shifting action, eliminating the need for manual driver intervention and improving the convenience and accuracy of operation.

[0037] The range-extended power unit also includes a dual-motor controller 10, which is electrically connected to both the generator 2 and the drive motor 3. The dual-motor controller 10 is used to adjust the operating states of the generator 2 and the drive motor 3 respectively according to the torque commands from the vehicle controller 9. The dual-motor controller 10 enables independent and precise control of power generation and drive, which is beneficial for optimizing energy distribution and improving system efficiency.

[0038] Furthermore, such as Figure 1 As shown, the range-extended power unit also includes a range extender controller 11 and an engine controller 12. The range extender controller 11 is communicatively connected to the vehicle controller 9 and the engine controller 12, and is used to adjust the operating point of the engine 1 according to the energy distribution command of the vehicle controller 9. This ensures that the engine 1 always operates in the optimal economic zone, further reducing fuel consumption and improving the efficiency of oil-electric conversion.

[0039] Optionally, the hydraulic shifting mechanism 6 is a wet clutch or hydraulic coupling, used for smooth switching between the first gear transmission mechanism 4 and the second gear transmission mechanism 5 without power interruption. This avoids power interruption, ensuring operational continuity and driving comfort.

[0040] Furthermore, this embodiment also provides a control method for the above-mentioned range-extended power unit, which includes the following steps: S1. Obtain the current working status of the vehicle, including whether the output mechanism PTO7 is in working condition; S2. When the output mechanism PTO7 is not working, the hydraulic shift mechanism 6 is connected to the first gear transmission mechanism 4. At this time, the engine 1 drives the generator 2 to generate electricity, and the generated electricity is supplied to the drive motor 3 to drive the vehicle to move. S3. When the output mechanism PTO7 is working, the hydraulic shift mechanism 6 is connected to the second gear transmission mechanism 5. At this time, part of the mechanical power of the engine 1 directly drives the output mechanism PTO7 through the second gear transmission mechanism 5, and the other part of the mechanical power is converted into electrical energy by the generator 2 and supplied to the drive motor 3 to drive the vehicle.

[0041] This control method detects the PTO's operating status and automatically switches the transmission path, enabling decoupling of PTO speed and vehicle speed, continuously variable transmission, and efficient direct drive of the PTO under heavy loads. This simplifies operation and reduces fuel consumption.

[0042] Furthermore, in step S2, based on the battery SOC value and the required drive power, one of the following four operating modes is selected for execution: Pure electric drive mode: When the SOC is higher than the first threshold (usually set to 70%~80%) and the drive power demand is lower than the preset value (10~20kw for 4L range extender), the drive motor 3 is driven only by battery power, and the engine 1 and generator 2 stop working. Power Follower Mode: When the SOC is in the middle range, the engine 1 adjusts the output power in real time according to the driving power demand, so that the electrical energy generated by the generator 2 just meets the demand of the drive motor 3. Driving charging mode: When the SOC is lower than the second threshold (usually set to 30%~40%), engine 1 runs at its most efficient point, and the excess electrical energy is charged into the battery; Power Enhancement Mode: When the drive power demand exceeds the maximum power generation of engine 1, the battery and generator 2 jointly supply power to drive motor 3.

[0043] The four operating modes are automatically selected based on the battery SOC and drive power demand, realizing intelligent energy distribution, ensuring that the engine operates efficiently while meeting the needs of various operating conditions, and further reducing fuel consumption.

[0044] Optionally, in step S3, the total output power of engine 1 is dynamically adjusted according to the power demand of the PTO, so that the sum of the mechanical power allocated to the output mechanism PTO7 and the mechanical power allocated to the generator 2 equals the actual output power of engine 1. When the PTO is working, the total output power of engine 1 needs to simultaneously meet two loads: the mechanical power demand of the PTO and the power demand of the generator 2. If the output power of engine 1 is less than the sum of the two, the PTO speed will decrease (affecting the work quality) or the generator 2 will generate insufficient power (leading to insufficient power for the drive motor 3). If the output power of engine 1 is greater than the sum of the two, the excess power has nowhere to be consumed, resulting in fuel waste. Therefore, by detecting the power demand of the PTO in real time, the throttle or fuel injection quantity of engine 1 is dynamically adjusted so that the output power of engine 1 is precisely equal to the sum of the mechanical power of the PTO and the power generated by the generator 2. This achieves "power supply on demand," ensuring stable operation of the PTO without wasting fuel, effectively avoiding power excess or deficiency, and improving energy utilization.

[0045] Furthermore, during gear shifting, the hydraulic shift mechanism 6 temporarily adjusts the torque of the drive motor 3 to compensate for power interruptions during the shifting process, achieving shock-free gear shifting. Although there is hydraulic buffering during the disengagement and engagement of the hydraulic shift mechanism 6, there may still be brief periods of discontinuity in power transmission (especially at the moment of clutch disengagement). When the hydraulic shift mechanism 6 shifts between first and second gear, the torque originally output by the drive motor 3 will experience a brief gap due to the change in the transmission path. At this time, the vehicle controller 9 instructs the dual-motor controller 10 to temporarily increase or decrease the electromagnetic torque of the drive motor 3, allowing it to continue outputting power to the wheels during the gear shifting interval, compensating for the torque gap caused by clutch action. In this way, the driving force on the wheels remains continuous during gear shifting, avoiding the jerking or power interruption that occurs during traditional tractor gear shifting, thereby improving driving smoothness and preventing damage to transmission components due to impact.

[0046] Furthermore, when the output mechanism PTO7 switches from the working state to the non-working state, the mechanical power allocated to the output mechanism PTO7 by engine 1 is first reduced to zero before the action of engaging the first gear transmission mechanism 4 in step S2 is executed. When PTO switches from the working state to the non-working state, if the gear is switched directly (from second gear back to first gear), the PTO shaft still carries an inertial load or residual mechanical power, which will cause the hydraulic shift mechanism 6 to disengage under load, exacerbating the wear of the friction plates; at the same time, suddenly disconnecting the PTO power may cause the connected implement (such as a rotary tiller) to be impacted due to inertia, damaging the universal joint or gears. Therefore, by first reducing the mechanical power allocated to PTO by engine 1 (for example, gradually reducing the throttle of engine 1 or adjusting the load of generator 2 through range extender controller 11), the torque and speed on the PTO shaft are gradually reduced to zero before the shifting action is executed. In this way, PTO disengages under no-load conditions, minimizing shifting impact, protecting the hydraulic shift mechanism 6 and the implement transmission chain, and improving the reliability and service life of the system.

[0047] In summary, the embodiments of the present invention provide a range-extended power unit and its control method, which have at least the following beneficial effects: (1) Decoupling of PTO speed and vehicle speed: PTO speed can be adjusted independently, and the quality of operations such as rotary tillage and sowing is not affected by vehicle speed fluctuations, significantly improving the consistency of operations.

[0048] (2) Stepless speed regulation, easy operation: The drive motor 3 achieves stepless speed regulation throughout the entire process. With two-speed transmission, it covers low-speed traction and high-speed transportation conditions, eliminating the need for frequent manual gear shifting and reducing labor intensity.

[0049] (3) PTO has high efficiency in heavy-duty operation: When PTO is working, the engine's mechanical power directly drives PTO, avoiding energy loss from the two conversions of "mechanical → electrical energy → mechanical", which is suitable for long-term heavy-duty operations such as deep plowing and rotary tillage.

[0050] (4) Reduced fuel consumption: Engine 1 always operates in the optimal economic zone, and with the intelligent switching of multiple modes, the overall fuel consumption is significantly lower than that of traditional mechanical transmission tractors.

[0051] (5) Smooth and uninterrupted gear shifting: The hydraulic shifting mechanism 6, in conjunction with the torque compensation of the drive motor 3, achieves smooth gear shifting without impact, ensuring the quality of continuous operation.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A range-extended power unit, characterized in that, include: Engine (1), generator (2), drive motor (3), first gear transmission mechanism (4), second gear transmission mechanism (5), hydraulic shift mechanism (6) and output mechanism PTO (7); The output shaft of the engine (1) is mechanically connected to the rotor shaft of the generator (2); The rotor shaft of the generator (2) is coaxially connected to the rotor shaft of the drive motor (3); The output end of the drive motor (3) can be selectively connected to the first gear transmission mechanism (4) or the second gear transmission mechanism (5) through the hydraulic shifting mechanism (6). The output end of the first gear transmission mechanism (4) is connected to the vehicle travel mechanism; The second-gear transmission mechanism (5) has two output ends, one of which is connected to the vehicle travel mechanism and the other is connected to the output mechanism PTO (7).

2. The range-extended power unit according to claim 1, characterized in that, It also includes a gear position controller (8), which is connected to the hydraulic shift mechanism (6) for receiving shift commands from the vehicle controller (9) and controlling the action of the hydraulic shift mechanism (6).

3. The range-extended power unit according to claim 2, characterized in that, It also includes a dual-motor controller (10), which is electrically connected to the generator (2) and the drive motor (3) respectively, and is used to adjust the working state of the generator (2) and the drive motor (3) according to the torque command of the vehicle controller (9).

4. The range-extended power unit according to claim 3, characterized in that, It also includes a range extender controller (11) and an engine controller (12), wherein the range extender controller (11) is communicatively connected to the vehicle controller (9) and the engine controller (12) and is used to adjust the operating point of the engine (1) according to the energy distribution command of the vehicle controller (9).

5. The range-extended power unit according to claim 4, characterized in that, The hydraulic shifting mechanism (6) is a wet clutch or hydraulic coupling, used for smooth switching between the first gear transmission mechanism (4) and the second gear transmission mechanism (5) without power interruption.

6. A control method for a range-extended power unit based on any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Obtain the current working status of the vehicle, including whether the output mechanism PTO (7) is in working status; S2. When the output mechanism PTO (7) is not working, the hydraulic shift mechanism (6) is controlled to connect to the first gear transmission mechanism (4). At this time, the engine (1) drives the generator (2) to generate electricity, and the generated electricity is supplied to the drive motor (3) to drive the vehicle to move. S3. When the output mechanism PTO (7) is working, the hydraulic shift mechanism (6) is controlled to connect to the second gear transmission mechanism (5). At this time, part of the mechanical power of the engine (1) directly drives the output mechanism PTO (7) through the second gear transmission mechanism (5), and the other part of the mechanical power is converted into electrical energy through the generator (2) and supplied to the drive motor (3) to drive the vehicle to move.

7. The control method according to claim 6, characterized in that, In step S2, based on the battery SOC value and the required drive power, one of the following four operating modes is selected for execution: Pure electric drive mode: When the SOC is higher than the first threshold and the drive power demand is lower than the preset value, the drive motor (3) is driven only by the battery, and the engine (1) and the generator (2) stop working; Power Follower Mode: When the SOC is in the middle range, the engine (1) adjusts the output power in real time according to the driving power demand, so that the electrical energy generated by the generator (2) just meets the demand of the drive motor (3); Driving charging mode: When the SOC is lower than the second threshold, the engine (1) operates at its most efficient point, and the excess electrical energy is charged into the battery; Power Enhancement Mode: When the drive demand power exceeds the maximum power generation of the engine (1), the battery and the generator (2) jointly supply power to the drive motor (3).

8. The control method according to claim 7, characterized in that, In step S3, the total output power of the engine (1) is dynamically adjusted according to the power required by the PTO, so that the sum of the mechanical power allocated to the output mechanism PTO (7) and the mechanical power allocated to the generator (2) is equal to the actual output power of the engine (1).

9. The control method according to claim 8, characterized in that, When the hydraulic shifting mechanism (6) is shifting, it temporarily adjusts the torque of the drive motor (3) to compensate for the power interruption during the shifting process, thereby achieving shock-free shifting.

10. The control method according to claim 8, characterized in that, When the output mechanism PTO (7) switches from the working state to the non-working state, the mechanical power allocated by the engine (1) to the output mechanism PTO (7) is reduced to zero, and then the action of engaging the first gear transmission mechanism (4) in step S2 is performed.

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