A range-extended four-wheel-drive hybrid tractor and control method thereof

Abstract

An extended-range four-wheel drive hybrid tractor and control method, including an engine and an electric motor, the engine is connected in series with a generator through a clutch, the generator outputs electric energy to various electrical components and a battery pack through an inverter; the hub motor is embedded in the front drive wheel of the tractor, the first drive motor drives the rear drive wheel through a mechanical coupling device; the second drive motor is coupled with the first drive motor torque in parallel through a mechanical coupling device to drive the rear drive wheel, and the second drive motor is mechanically connected to a transmission device through a clutch to drive a power output device; the engine is connected to the transmission device through a clutch, and can drive the power output device alone or together with the second drive motor; the vehicle controller is connected to the corresponding components through the controller between the components. The present invention has multiple working modes and electric four-wheel drive modes, which can meet the complex working conditions of the tractor, switch the optimal working mode according to different battery capacity states, and improve fuel economy.

Description

Technical Field

[0001] The present invention relates to a new energy tractor drive system, and particularly to an extended-range four-wheel drive hybrid tractor and a control method, belonging to the field of agricultural machinery. Background Art

[0002] As an important agricultural machinery, tractors are developing towards large-scale and intelligent trends with the development of large-scale agricultural planting and green agriculture. Traditional fuel tractors currently face problems such as high fuel consumption, poor emission performance, and high noise. High-power tractors, due to the wide range of torque requirements, also face problems such as complex transmission system structures, excessive transmission gears, high prices, and great technical difficulties.

[0003] To solve the above problems, new energy tractors have become an important trend in the future development of tractors. Electric tractors have the advantages of zero emissions and high efficiency, but problems such as low battery energy density and short endurance that need to be urgently solved have not been broken through. Therefore, hybrid tractors, as transitional products in the development of electric tractors, not only have the characteristics of low energy consumption and low emissions of electric tractors but also have the characteristics of long endurance of traditional tractors, becoming the best choice for the current development of new energy tractors.

[0004] Hybrid technology is widely used in passenger cars and the technology research and development is relatively mature. It also develops relatively rapidly in commercial vehicles. The research and development and application of hybrid technology in tractors started relatively late, especially the research and development of hybrid technology applied to high-power tractors is less. At present, there are no market application products in China. At the same time, due to the extremely complex operating conditions of tractors, the speed requirement is not high, but the torque requirement is large, and the torque requirement fluctuates greatly, which is significantly different from passenger cars and commercial vehicles. It is impossible to refer to existing mature hybrid systems for research and development. Therefore, in view of the development trend of high-power tractors and the operating conditions and characteristics of tractors, designing a hybrid system is of great significance for improving the fuel economy and emission performance of tractors. Summary of the Invention

[0005] Object of the Invention: In order to solve the above problems, the present invention provides an extended-range four-wheel drive hybrid tractor and a control method, which have the advantages of good economy, strong power, excellent emission performance, high matching degree of agricultural implements, and adaptability to various complex operating conditions.

[0006] Technical Solution

[0007] An extended-range four-wheel drive hybrid tractor includes a vehicle controller, an engine, and a first drive motor. The vehicle controller controls the engine to drive a power output device, and the vehicle controller controls the first drive motor to drive the rear drive wheels to rotate. The engine is connected to the power output device through a first clutch C 1Mechanically connected to a transmission device, the transmission device outputs power to a power output device, and the engine is connected to the second clutch C 2 Mechanically connected to a generator, the generator is electrically connected to a battery pack through an inverter, and the battery pack is connected to an external power grid for charging through a power receiving device; the battery pack supplies power to a hub motor, a first drive motor, and a second drive motor through an inverter. The hub motor is connected to the front drive wheel at the same speed. The first drive motor is mechanically connected to a mechanical coupling device, a gearbox, a reducer, and a differential in sequence. The differential drives the rear drive wheel to rotate through a working half shaft. A wheel speed sensor and a braking device are provided on the rear drive wheel. The second drive motor is connected to the third clutch C 3 Mechanically connected to a transmission device, the second drive motor outputs power to a power output device through the transmission device. The second drive motor and the engine can selectively drive the power output device through torque coupling of the transmission device. The output end of the second drive motor is mechanically connected to a hydraulic pump. The second drive motor is connected to the fourth clutch C 4 Mechanically connected to a mechanical coupling device, the second drive motor and the first drive motor can selectively drive the rear drive wheel to rotate through torque coupling of the mechanical coupling device.

[0008] In the technical solution of the present invention, when the battery pack is in a fully charged state, the rear drive wheel is driven by the first drive motor, or the front drive wheel is driven by the hub motor. At the same time, both can work together to realize the arbitrary switching between two-wheel drive and four-wheel drive of the whole vehicle. Compared with the traditional mechanical method of driving the wheel to rotate through a differential, the direct connection of the hub motor simplifies the transmission structure of the tractor and reduces the weight of the whole vehicle. The second drive motor is set as a power compensation motor. When the first drive motor does not meet the power required by the current working condition, the second drive motor and the first drive motor are power-coupled through a mechanical coupling device to provide more power output. Compared with single-motor drive, the load of the motor is reduced, the motor works in a good strength range, and the service life of the motor is improved. When the battery pack is not fully charged, the engine works to charge the battery pack, and at the same time drives the electrical energy output by the generator to supply power to the hub motor, the first drive motor, and the second drive motor. When the tractor needs power output, the engine drives the power output device to rotate. When the power required by the power output device increases, the second drive motor is torque-coupled through the transmission device and jointly drives the power output device to rotate with the engine, reducing the working load of the engine and improving the working efficiency of the whole vehicle.

[0009] Preferred option: The vehicle controller is respectively connected to the engine, generator, hub motor, battery pack, first drive motor, second drive motor and braking device through the engine controller, generator controller, hub motor controller, battery pack controller, first drive motor controller, second drive motor controller and braking device controller for signal connection.

[0010] By providing corresponding controllers between each device and the vehicle controller, vehicle control can be made more precise, the signals sent to each device can be more accurate, and the precision of the overall vehicle operation can be improved.

[0011] Preferred option: The transmission device includes a coaxial first gear G 1 and a third gear G 3 . The output shaft of the engine is connected to the intermediate shaft of the first gear G 1 and the third gear G 1 through a first clutch C 3 . A second gear G 1 meshing with the first gear G 2 and a fourth gear G 3 meshing with the third gear G 4 are provided on the input shaft of the power output device. .

[0012] The transmission device is used to couple the torques of the second drive motor and the engine to jointly drive the operation of the power output device. By adopting the method of combining two sets of gears, the transmission device can provide outputs at different speeds, effectively expanding the working range of the tractor.

[0013] Preferred option: The transmission device is connected to the intermediate shaft of the fifth gear G 3 through a third clutch C 5 . A sixth gear G 5 meshing with the fifth gear G 6 is provided on the output shaft of the second drive motor. .

[0014] Power is transmitted between the second drive motor and the transmission device through meshing gears, resulting in low energy loss and higher transmission efficiency.

[0015] Preferred option: When the engine drives the power output device alone, it can select any one of the two combination methods of the first gear G 1 meshing with the second gear G 2 or the third gear G 3 meshing with the fourth gear G 4 . When the second drive motor drives the power output device alone, it can arbitrarily adjust the speed of the power output device within the working range.

[0016] When the engine drives the power output device alone, it can also switch the corresponding gear meshing combination within the adjustable range of the transmission according to the requirements of the power output device. When the second drive motor drives the power output device, the speed of the power output device can be adjusted arbitrarily.

[0017] Preferred option, the mechanical coupling device includes a seventh gear G 7 and an eighth gear G 8 When the fourth clutch C 4 is closed, the first drive motor and the second drive motor achieve torque coupling. The first drive motor and the second drive motor drive the rear drive wheels through a gearbox, and the gearbox is a two-speed gearbox.

[0018] The power coupling of the first drive motor and the second drive motor is realized by means of gear meshing. The device is convenient and has a good transmission effect. The rear drive system adopts a single-motor plus two-speed gearbox drive and a dual-motor torque coupling plus two-speed gearbox drive mode to meet the low-energy consumption requirements of a high-power tractor under various transportation conditions.

[0019] A control method for an extended-range four-wheel drive hybrid tractor, characterized in that: when the SOC of the battery pack is greater than SOC max , pure electric drive is adopted for walking and the power output device outputs. The specific power transmission path is as follows:

[0020] When walking at high speed with high torque and there is no output from the power output device, the first drive motor and the second drive motor are torque-coupled and the second gear is used for rear-wheel drive output, the hub motor is used for front-wheel drive output, and the battery pack outputs electrical energy;

[0021] When walking at high speed with medium torque or when walking at medium speed with medium to high torque and there is no output from the power output device, the first drive motor and the second drive motor are torque-coupled and the second gear is used for rear-wheel drive output, and the hub motor does not participate in driving and only works in the braking energy recovery mode;

[0022] When walking at high speed with low torque and there is no output from the power output device, the first drive motor is used and the second gear is used for rear-wheel drive, and the hub motor does not participate in driving and only works in the braking energy recovery mode;

[0023] When walking at medium speed with medium to high torque and there is an output from the power output device, the first drive motor is used, the transmission is in the second gear for rear-wheel drive output, the hub motor is used for front-wheel drive output, and the second drive motor drives the power output device to output;

[0024] When walking at medium to low speed with low torque and there is no output from the power output device, the hub motor is used to drive the walking;

[0025] When walking at medium to low speed with low torque and there is an output from the power output device, the hub motor is used to drive the walking; the second drive motor drives the power output device to output;

[0026] When traveling at low speed with medium to high torque, there is no output from the power take-off device. The first drive motor and the second drive motor are coupled, and the transmission outputs in the first gear for rear-wheel drive.

[0027] When traveling at low speed with medium to high torque, there is output from the power take-off device. The first drive motor is used, the transmission outputs in the first gear for rear-wheel drive, the hub motors output for front-wheel drive, and the second drive motor drives the power take-off device.

[0028] Preferred option, when the SOC of the battery pack is less than SOC max , greater than SOC min When it is, a hybrid drive mode with engine power compensation is adopted. The specific mode classifications are as follows:

[0029] Under low-speed, medium-speed, and high-speed low-torque working conditions, a pure electric drive mode is adopted;

[0030] Under low-speed, medium-speed, and high-speed medium to high-torque working conditions, there is no output from the power take-off device. The engine stably outputs power at the optimal working point for power generation. When the power generation power is less than the driving demand power, the battery pack compensates for the power; when the engine power generation power is greater than the driving power demand, a part is used for the drive system, and the excess power is used to charge the battery pack;

[0031] Under low-speed, medium-speed, and high-speed medium to high-torque working conditions, there is output from the power take-off device. The output power of the power take-off device is mechanically output by the engine. The engine speed is determined by the speed of the power take-off device. At this speed, the engine torque output is stable at the optimal fuel working point. When the torque demand of the power take-off device is less than the engine's optimal working point torque, a part of the torque output is used to drive the power take-off device, and the other part is used for power generation to provide driving for traveling. When the torque demand of the power take-off device is greater than the engine's optimal working point torque, the remaining torque demand is compensated by the second drive motor.

[0032] Preferred option, when the SOC of the battery pack is less than or equal to SOC min When it is, an engine drive plus charging mode is adopted. The specific mode classifications are as follows:

[0033] When there is no output from the power take-off device, the engine operates on the optimal fuel consumption power curve. The power output from the engine to the generator is not less than the optimal fuel efficiency working point and greater than the vehicle's demand power A. The vehicle's demand power A includes the driving demand power and the battery pack charging power. When the driving power demand is less than the optimal working point power, the power of the engine other than the power required for driving is used for battery pack charging. This mode continues until it is charged to the battery pack SOC = %. It switches to the mode where SOC is less than SOC max Greater than SOC min When the driving power demand is greater than the engine's optimal working point power, the engine operating point moves along the optimal fuel consumption power curve;

[0034] When the power output device outputs, the engine output power is the vehicle demand power B. The vehicle demand power B includes the driving demand power, the battery pack charging power, and the power output device output power. The engine output power is greater than the optimal efficiency operating point matched by the power output device speed. The power of the engine output exceeding the power output of the power output device and the driving demand power is used to charge the battery pack. This mode continues until the battery pack is charged to SOC = %, and then switches to the mode where SOC is less than SOC max Greater than SOC min When the sum of the driving demand power and the power output device demand power is greater than the engine's best operating point power, the battery pack stops charging, and the electric energy converted by the engine output acts on the drive system and the power output device.

[0035] Preferred option: When the power output device has no output, the engine controller controls the engine output power to move along the best fuel consumption power curve at equal difference points. The equal difference constant in the equal difference points is K. When the driving demand power is greater than the engine power generation power, the battery pack stops charging, and the electric energy converted by the engine output only acts on the drive system; when the engine operating point moves at equal difference according to the vehicle demand power A, a delay time T is set. During the delay time T, when the engine output power is greater than the vehicle demand power A and the difference between the engine output power and the vehicle demand power A is less than the equal difference constant K, the engine output power remains unchanged after the delay time T ends; when the power output by the engine is lower than or equal to the vehicle system demand power and the difference between the engine output power and the vehicle demand power A is greater than or equal to the equal difference constant K, the engine output power changes to the nearest equal difference array value greater than or equal to the vehicle demand power A after the delay time T ends;

[0036] When the power output device outputs, when the engine operating point moves at equal difference according to the vehicle demand power B, a delay time T is set. During the delay time T, when the engine output power is greater than the vehicle demand power B and the difference between the engine output power and the vehicle demand power B is less than the equal difference constant K, the engine output power remains unchanged after the delay time T ends; when the power output by the engine is lower than or equal to the vehicle system demand power and the difference between the engine output power and the vehicle demand power B is greater than or equal to the equal difference constant K, the engine output power changes to the nearest equal difference array value greater than or equal to the vehicle demand power B after the delay time T ends. Beneficial effects

[0037] First, the rear-wheel drive system adopts a single-motor plus two-speed transmission drive and a dual-motor torque coupling plus two-speed transmission drive mode, meeting the low-energy consumption requirements of large-power tractors under various transportation conditions;

[0038] Second, the front-wheel drive system uses a hub motor with a smaller power to replace the traditional mechanical differential four-wheel drive system, which improves the transmission efficiency of the system, streamlines the transmission system, reduces the vehicle weight, can flexibly switch between two-wheel drive mode and four-wheel drive mode, and improves the accuracy of four-wheel drive control;

[0039] Third, the working state of the engine is decoupled from the operating state of the tractor, which enables the engine to work in the high-efficiency area as much as possible. At the same time, the engine retains the direct drive power output device, further reducing the energy conversion loss.

[0040] Fourth, the working state of the whole vehicle follows the change of the battery SOC state, and can select the optimal combination according to different working conditions to ensure sufficient power output under each working condition. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0042] Figure 1 It is a schematic structural diagram of the range-extended four-wheel drive hybrid tractor of the present invention.

[0043] Figure 2 It is a schematic structural diagram of the range-extended four-wheel drive hybrid tractor of the present invention.

[0044] Figure 3 It is a schematic structural diagram of the transmission device and the mechanical coupling device of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0046] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0047] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0048] As Figures 1 to 2 shown, an extended-range four-wheel drive hybrid tractor includes a vehicle controller 1, an engine 2, and a first drive motor 3. The vehicle controller 1 controls the engine 2 to drive a power output device 7, and the vehicle controller 1 controls the first drive motor 3 to drive a rear drive wheel 4 to rotate. The engine 2 is mechanically connected to a transmission device 6 through a first clutch C 1 5, and the transmission device 6 outputs power to the power output device 7. The engine 2 is mechanically connected to a generator 9 through a second clutch C 2 8. The generator 9 is electrically connected to a battery pack 11 through an inverter 10, and the battery pack 11 is connected to an external power grid through a power receiving device 12 for charging. The battery pack 11 supplies power to a hub motor 13, the first drive motor 3, and a second drive motor 29 through the inverter 10. The hub motor

[0049] is connected to a front drive wheel 14 at the same rotational speed. The first drive motor 3 is sequentially mechanically connected to a mechanical coupling device 15, a gearbox 16, a speed reducer 17, and a differential 18. The differential 18 drives the rear drive wheel 4 to rotate through a working half shaft. A wheel speed sensor 19 and a braking device 20 are provided on the rear drive wheel 4. The second drive motor 29 is mechanically connected to the transmission device 6 through a third clutch C 3 30. The second drive motor 29 outputs power to the power output device 7 through the transmission device 6. The second drive motor 29 and the engine 2 can selectively torque-couple through the transmission device 6 to drive the power output device 7. The output end of the second drive motor 29 is mechanically connected to a hydraulic pump 31. The second drive motor 29 is mechanically connected to the mechanical coupling device 15 through a fourth clutch C 4 21. The second drive motor 29 and the first drive motor 3 can selectively torque-couple through the mechanical coupling device 15 to drive the rear drive wheel 4 to rotate.

[0050] In the technical solution of the present invention, when the battery pack is in a fully charged state, the rear drive wheels are driven by the first drive motor, or the front drive wheels are driven by the hub motor. At the same time, both can work together to achieve arbitrary switching between two-wheel drive and four-wheel drive of the whole vehicle. The use of the hub motor to drive the front drive is relative to the traditional mechanical method of driving the wheels to rotate through a differential. The direct connection method of the hub motor simplifies the transmission structure of the tractor and reduces the weight of the whole vehicle. A second drive motor is set as a power compensation motor. When the first drive motor does not meet the power required by the current working condition, the second drive motor is power-coupled with the first drive motor through a mechanical coupling device to provide more power output. Compared with single-motor drive, the load on the motor is reduced, the motor works in a good strength range, and the service life of the motor is improved. When the battery pack is not fully charged, the engine works to charge the battery pack, and at the same time drives the electric energy output by the generator to supply the hub motor, the first drive motor, and the second drive motor. When the tractor needs power output, the engine drives the power output device to rotate. When the power required by the power output device increases, the second drive motor is torque-coupled through the transmission device and jointly drives the power output device to rotate with the engine, reducing the working load of the engine and improving the working efficiency of the whole vehicle.

[0051] The vehicle controller 1 is respectively signal-connected to the engine 2, the generator 9, the hub motor 13, the battery pack 11, the first drive motor 3, the second drive motor 29, and the braking device 20 through the engine controller 22, the generator controller 23, the hub motor controller 24, the battery pack controller 25, the first drive motor controller 26, the second drive motor controller 27, and the braking device controller 28.

[0052] As Figure 3 shown, the transmission device 6 includes a coaxial first gear G 1 61 and a third gear G 3 62. The output shaft of the engine 2 is connected to the intermediate shaft of the first gear G 1 61 and the third gear G 1 62 through the first clutch C 3 5. A second gear G 1 63 that meshes with the first gear G 2 61 and a fourth gear G 3 64 that meshes with the third gear G 4 62 are provided on the input shaft of the power output device 7. The transmission device 6 is connected to the intermediate shaft of the fifth gear G 3 30 through the third clutch C 5 65. A sixth gear G 5 65 that meshes with the fifth gear G 666. When the engine 2 drives the power output device 7 alone, the first gear G 1 61 can be engaged with the second gear G 2 63 or the third gear G 3 62 and the fourth gear G 4 64 can be engaged in any one of the two combination modes; when the second drive motor 29 drives the power output device 7 alone, the rotational speed of the power output device 7 within the working range can be adjusted arbitrarily.

[0053] As Figure 3 shown, the mechanical coupling device 15 includes the seventh gear G 7 151 and the eighth gear G 8 152 that mesh with each other. When the second clutch C 2 8 is closed, the first drive motor 3 and the second drive motor 29 achieve torque coupling. The first drive motor 3 and the second drive motor 29 drive the rear drive wheel 4 through the transmission 16, and the transmission 16 is a two-speed transmission 16.

[0054] A control method for an extended-range four-wheel drive hybrid tractor. When the SOC of the battery pack 11 is greater than SOC max , where SOCmax is selected as 70% in this embodiment, but not limited to 70%, pure electric drive is used for traveling and the power output device 7 outputs. The specific power transmission path is as follows:

[0055] When traveling at high speed with high torque, there is no output from the power output device 7. The first drive motor 3 and the second drive motor 29 are torque-coupled and output in second gear for rear-wheel drive, the in-wheel motor 13 outputs for front-wheel drive, and the battery pack 11 outputs electrical energy;

[0056] When traveling at high speed with medium torque or at medium speed with medium to high torque, there is no output from the power output device 7. The first drive motor 3 and the second drive motor 29 are torque-coupled and output in second gear for rear-wheel drive, and the in-wheel motor 13 does not participate in driving and only works in the braking energy recovery mode;

[0057] When traveling at high speed with low torque, there is no output from the power output device 7. The first drive motor 3 drives in second gear in the rear-wheel drive mode, and the in-wheel motor 13 does not participate in driving and only works in the braking energy recovery mode;

[0058] When traveling at medium speed with medium to high torque, there is an output from the power output device 7. The first drive motor 3 outputs in second gear of the transmission for rear-wheel drive, the in-wheel motor 13 outputs for front-wheel drive, and the second drive motor 29 drives the power output device 7 to output;

[0059] When traveling at medium to low speed with low torque, there is no output from the power output device 7, and the in-wheel motor 13 is used to drive the vehicle;

[0060] When walking at low speed with low torque, the power output device 7 outputs power, and the hub motor 13 is used to drive the vehicle; the second drive motor 29 drives the power output device 7 to output power;

[0061] When walking at low speed with medium to high torque, the power output device 7 does not output power. The first drive motor 3 and the second drive motor 29 are coupled, and the transmission 16 outputs power in the first gear for rear-wheel drive;

[0062] When walking at low speed with medium to high torque, the power output device 7 outputs power. The first drive motor 3, the transmission 16 outputs power in the first gear for rear-wheel drive, the hub motor 13 outputs power for front-wheel drive, and the second drive motor 29 drives the power output device 7.

[0063] When the SOC of the battery pack 11 is less than SOC max , greater than SOC min where SOCmin is selected as 20% in this embodiment, but not limited to 20%, a hybrid drive mode with engine 2 power compensation is adopted. The specific mode classification is as follows:

[0064] Under low-torque conditions at low, medium, and high speeds, a pure electric drive mode is adopted;

[0065] Under medium to high torque conditions at low, medium, and high speeds, the power output device 7 does not output power. The engine 2 stably outputs power to generate electricity at the optimal operating point. When the power generation power is less than the driving demand power, the battery pack 11 compensates for the power; when the power generation power of the engine 2 is greater than the driving power demand, a part is used for the drive system, and the excess power is used to charge the battery pack 11;

[0066] Under medium to high torque conditions at low, medium, and high speeds, the power output device 7 outputs power. The output power of the power output device 7 is mechanically output by the engine 2. The engine speed of the engine 2 is determined by the speed of the power output device 7. At this speed, the torque output of the engine 2 is stable at the optimal fuel operating point. When the torque demand of the power output device 7 is less than the torque at the best operating point of the engine 2, a part of the torque output is used to drive the power output device 7, and the other part is used to generate electricity for driving the vehicle. When the torque demand of the power output device 7 is greater than the torque at the best operating point of the engine 2, the remaining torque demand is compensated by the second drive motor 29.

[0067] When the SOC of the battery pack 11 is less than or equal to SOC min a driving and charging mode with the engine 2 is adopted. The specific mode classification is as follows:

[0068] First, the engine 2 works with an initial large output power value of 70% of the full load to provide energy for the vehicle drive system and the power output device. If the power demand is too large, the operating point of the engine moves on the optimal fuel consumption curve to meet the vehicle power demand, and the remaining power is used to charge the battery until the SOC of the battery pack 11 is greater than or equal to 30%;

[0069] When the SOC of the battery pack 11 is less than 20%, the charging priority mode is triggered, and the battery pack stops discharging. At this time, the energy output by the engine is mainly used to charge the battery pack. The driving demand power and the power demand of the power output device are also provided by the engine. At this time, the operating point of the engine moves on the optimal fuel consumption curve. When the battery pack is charged to SOC greater than or equal to 30%, the battery pack is allowed to discharge to prepare for the driving demand power and the power demand of the power output device for instantaneous boost. When the demand power of one or both of them increases, the battery pack discharges to provide energy. If there is no instantaneous boost in the driving demand power or the power demand of the power output device, the priority charging mode ends until SOC = 50% and switches to the mode where SOC is greater than SOCmin and less than SOCmax.

[0070] When the power output device 7 has no output, the engine 2 operates on the optimal fuel consumption power curve. The power output from the engine 2 to the generator 9 is not less than the optimal operating point of fuel efficiency and the power generated by the generator is greater than the vehicle demand power A. The vehicle demand power A includes the driving demand power and the charging power of the battery pack 11. When the driving power demand is less than the power at the optimal operating point, the power of the engine 2 other than the power required for driving is used to charge the battery pack 11. This mode switches to the mode where SOC is less than SOC until the battery pack 11 is charged to SOC = 50%. max Greater than SOC min When the driving power demand is greater than the power of the engine 2 at the optimal operating point, the operating point of the engine 2 moves along the optimal fuel consumption power curve; the engine controller 22 controls the output power of the engine 2 to move at equal - difference points along the optimal fuel consumption power curve. The equal - difference constant in the equal - difference points is K. When the instantaneous driving demand power is greater than the power generated by the engine, the battery pack 11 interrupts charging and releases electrical energy. The electrical energy converted by the output of the engine 2 only acts on the drive system; when the operating point of the engine moves at equal - difference according to the vehicle demand power A, a delay time T is set. During the delay time T, the electric work obtained by integrating the electric power converted from the output power of the engine is greater than the vehicle demand work, and when the difference between the output power of the engine 2 and the average vehicle demand power A is less than the equal - difference constant K, the output power of the engine 2 remains unchanged after the delay time T ends; during the delay time T, when the power output by the engine 2 is lower than or equal to the average vehicle system demand power, or when the difference between the output power of the engine 2 and the average vehicle demand power A is greater than or equal to the equal - difference constant K, the output power of the engine 2 changes to the nearest equal - difference array value greater than or equal to the average vehicle demand power A within the vehicle time T after the delay time T ends.

[0071] When the power output device 7 outputs power, the output power of the engine 2 is the vehicle demand power B. The vehicle demand power B includes the driving demand power, the charging power of the battery pack 11, and the output power of the power output device 7. The output power of the engine 2 is greater than the best efficiency operating point matched by the speed of the power output device 7. The power of the engine 2 exceeding the output power of the power output device 7 and the driving demand power is used to charge the battery pack 11. This mode switches to the SOC less than SOC until the SOC of the battery pack 11 is charged to 50%. max Greater than SOC min Mode. When the sum of the driving demand power and the demand power of the power output device 7 is greater than the power at the best operating condition point of the engine 2, the battery pack 11 stops charging, and the electric energy converted by the output of the engine 2 acts on the drive system and the power output device 7. When the operating point of the engine is set with a delay time T when moving in an arithmetic progression according to the vehicle demand power B, within the delay time T, the output power of the engine 2 is greater than the average vehicle demand power B, and when the difference between the output power of the engine 2 and the average vehicle demand power B within the time T is less than the arithmetic constant K, the output power of the engine 2 remains unchanged after the end of the delay time T; within the time T, when the power output by the engine 2 is lower than or equal to the average demand power of the vehicle system, or when the difference between the output power of the engine 2 and the vehicle demand power B is greater than or equal to the arithmetic constant K, the output power of the engine 2 changes to the value of the arithmetic progression array closest to being greater than or equal to the vehicle demand power B after the end of the delay time T.

[0072] In the present specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and reference can be made to the description in the method part for related parts.

[0073] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An extended-range four-wheel-drive hybrid tractor, comprising a vehicle controller (1), an engine (2) and a first drive motor (3), wherein the vehicle controller (1) controls the engine (2) to drive a power output device (7), and the vehicle controller (1) controls the first drive motor (3) to drive a rear drive wheel (4) to rotate, characterized in that: The engine (2) is mechanically connected to the transmission device (6) through a first clutch C1 (5), and the transmission device (6) outputs power to the power output device (7). The engine (2) is mechanically connected to the generator (9) through a second clutch C2 (8), and the generator (9) is electrically connected to the battery pack (11) through an inverter (10). The battery pack (11) is connected to an external power grid through a power receiving device (12) for charging; the battery pack (11) supplies power to the wheel hub motor (13), the first drive motor (3) and the second drive motor (29) through the inverter (10). The wheel hub motor (13) is connected to the front drive wheel (14) at the same speed. The first drive motor (3) is mechanically connected to the mechanical coupling device (15), the gearbox (16), the reducer (17) and the differential (18) in sequence. The differential (18) is connected to the working semi-automatic transmission (16) through a transmission (17). The shaft drives the rear drive wheel (4) to rotate. The rear drive wheel (4) is provided with a wheel speed sensor (19) and a brake device (20). The second drive motor (29) is mechanically connected to the transmission device (6) through a third clutch C3 (30). The second drive motor (29) outputs power to a power output device (7) through the transmission device (6). The second drive motor (29) and the engine (2) can selectively drive the power output device (7) through torque coupling of the transmission device (6). The output end of the second drive motor (29) is mechanically connected to a hydraulic pump (31). The second drive motor (29) is mechanically connected to a mechanical coupling device (15) through a fourth clutch C4 (21). The second drive motor (29) and the first drive motor (3) can selectively drive the rear drive wheel (4) to rotate through torque coupling of the mechanical coupling device (15).

2. The extended-range four-wheel-drive hybrid tractor according to claim 1, characterized in that: The vehicle controller (1) is connected to the engine (2), the generator (9), the wheel hub motor (13), the battery pack (11), the first drive motor (3), the second drive motor (29) and the brake device (20) respectively via signals of an engine controller (22), a generator controller (23), a wheel hub motor controller (24), a battery pack controller (25), a first drive motor controller (26), a second drive motor controller (27) and a brake device controller (28).

3. The extended-range four-wheel-drive hybrid tractor according to claim 1, characterized in that: The transmission device (6) comprises a coaxial first gear G1 (61) and a third gear G3 (62); the output shaft of the engine (2) is connected to the intermediate shaft of the first gear G1 (61) and the third gear G3 (62) via a first clutch C1 (5); and the input shaft of the power output device (7) is provided with a second gear G2 (63) meshing with the first gear G1 (61) and a fourth gear G4 (64) meshing with the third gear G3 (62).

4. The extended-range four-wheel-drive hybrid tractor according to claim 3, characterized in that: The transmission device (6) is connected to the intermediate shaft of the fifth gear G5 (65) via the third clutch C3 (30), and the output shaft of the second drive motor (29) is provided with a sixth gear G6 (66) meshing with the fifth gear G5 (65).

5. The extended-range four-wheel-drive hybrid tractor according to claim 4, characterized in that: When the engine (2) drives the power output device (7) alone, any one of the two combinations of meshing of the first gear G1 (61) and the second gear G2 (63) or meshing of the third gear G3 (62) and the fourth gear G4 (64) can be selected; when the second drive motor (29) drives the power output device (7) alone, the speed of the power output device (7) can be arbitrarily adjusted within the working range.

6. The extended-range four-wheel-drive hybrid tractor according to claim 1, characterized in that: The mechanical coupling device (15) comprises a seventh gear G7 (151) and an eighth gear G8 (152) meshing with each other, and when the fourth clutch C4 (21) is closed, the first drive motor (3) and the second drive motor (29) achieve torque coupling, and the first drive motor (3) and the second drive motor (29) drive the rear drive wheel (4) through a gearbox (16), and the gearbox (16) is a two-speed gearbox (16).

7. The control method of the extended-range four-wheel-drive hybrid tractor according to any one of claims 1 to 6, characterized in that: When the SOC of the battery pack (11) is greater than SOC max When the vehicle is in a state of being driven by pure electricity, the power output device (7) is used for output. The specific power transmission path is as follows: When the vehicle is traveling at high speed and with high torque, there is no power output device (7) for output, and the first drive motor (3) and the second drive motor (29) are used for torque coupling to output the second-gear rear drive, the wheel hub motor (13) for the front drive, and the battery pack (11) for outputting electrical energy; When driving at high speed and medium torque or driving at medium speed and medium-large torque, there is no power output device (7) output, and the first drive motor (3) and the second drive motor (29) are used to couple the torque to produce a second-gear rear-drive output, and the wheel hub motor (13) does not participate in the drive and only works in a braking energy recovery mode; When traveling at high speed and low torque, there is no output from the power output device (7), the first drive motor (3) is used, and the rear-drive mode is driven in second gear, and the wheel hub motor (13) does not participate in the driving and only works in a braking energy recovery mode; When the vehicle is traveling at a medium speed and with a medium torque, there is a power output device (7) for output, the first drive motor (3), the second gear of the transmission for rear-wheel drive output, the wheel hub motor (13) for front-wheel drive output, and the second drive motor (29) for driving the power output device (7) for output; When the vehicle is traveling at medium or low speed and with low torque, there is no output from the power output device (7), and the wheel hub motor (13) is used to drive the vehicle to travel; When traveling at medium or low speeds and with low torque, the power output device (7) outputs, and the wheel hub motor (13) drives the vehicle to travel; the second drive motor (29) drives the power output device (7) to output; When traveling at low speed and medium to large torque, there is no power output device (7) outputting, and the first drive motor (3) and the second drive motor (29) are coupled, and the gearbox (16) outputs rear-drive in first gear; When traveling at low speed and with medium to high torque, there is a power output device (7) for output, using a first drive motor (3), a first gear rear-drive output of a gearbox (16), a front-drive output of a wheel hub motor (13), and a second drive motor (29) to drive the power output device (7).

8. The control method of the extended-range four-wheel-drive hybrid tractor according to claim 7, characterized in that: When the SOC of the battery pack (11) is less than SOC max , greater than SOC min When the hybrid driving mode of engine (2) power compensation is adopted, the specific modes are classified as follows: Pure electric drive mode is used under low-torque conditions at low, medium and high speeds; Under medium and large torque conditions at low speed, medium speed and high speed, there is no output from the power output device (7), the engine (2) stably outputs power at the optimal operating point, and when the power generated is less than the required driving power, the battery pack (11) performs power compensation; when the power generated by the engine (2) is greater than the required driving power, a portion of it is used for the driving system, and the excess power is used for charging the battery pack (11); Under medium and large torque working conditions at low speed, medium speed and high speed, there is output from a power output device (7), the output power of the power output device (7) is mechanically output by the engine (2), the speed of the engine (2) is determined by the speed of the power output device (7), at which the torque output of the engine (2) is stabilized at the optimal fuel working point, when the torque demand of the power output device (7) is less than the torque at the optimal working point of the engine (2), a part of the torque output is used to drive the power output device (7), and the other part is used to generate electricity to provide driving travel, when the torque demand of the power output device (7) is greater than the torque at the optimal working point of the engine (2), the remaining torque demand is compensated by the second drive motor (29).

9. The control method of the extended-range four-wheel-drive hybrid tractor according to claim 7, characterized in that: When the SOC of the battery pack (11) is less than or equal to SOC min When the engine (2) is used to drive and charge, the specific modes are classified as follows: First, the engine (2) operates at a relatively large output power to provide energy for the vehicle drive system and the power output device. The initial value is 70% of the full load. If the power demand is too large, the engine operating point moves on the optimal fuel consumption curve to meet the power demand of the vehicle. The remaining power is used to charge the battery until the SOC of the battery pack (11) is greater than or equal to 30%. When the power output device (7) has no output, the engine (2) operates on the optimal fuel consumption power curve, the power output of the engine (2) to the generator (9) is not less than the optimal operating point of fuel efficiency and the generator power is greater than the vehicle power demand A, the vehicle power demand A includes the driving power demand and the battery pack (11) charging power, when the driving power demand is less than the optimal operating point power, the power of the engine (2) other than the power required for driving is used to charge the battery pack (11), and this mode is switched until the battery pack (11) is charged to SOC=50% and the SOC is less than SOC max Greater than SOC min mode, when the driving power demand is greater than the optimal operating point power of the engine (2), the operating point of the engine (2) moves along the optimal fuel consumption power curve; When the power output device (7) has output, the output power of the engine (2) is the vehicle demand power B, the vehicle demand power B includes the driving demand power, the battery pack (11) charging power and the power output device (7) output power, the engine (2) output power is greater than the optimal efficiency operating point of the power output device (7) speed matching, the power output of the engine (2) exceeding the output power of the power output device (7) and the driving demand power is used to charge the battery pack (11), and this mode is switched to a state of charge (SOC) less than SOC until the battery pack (11) is charged to SOC=50%. max Greater than SOC min In this mode, when the sum of the required driving power and the required power of the power output device (7) is greater than the power at the optimal operating point of the engine (2), the battery pack (11) stops charging and the converted electric energy output by the engine (2) acts on the driving system and the power output device (7).

10. The control method of the extended-range four-wheel-drive hybrid tractor according to claim 9, characterized in that: When the power output device (7) has no output, the engine controller (22) controls the output power of the engine (2) to move along the optimal fuel consumption power curve according to an arithmetic progression point, the arithmetic progression constant in the arithmetic progression point is K, and when the instantaneous driving demand power is greater than the engine power generation power, the battery pack (11) stops charging, and the electric energy converted by the output of the engine (2) only acts on the drive system; when the engine operating point moves according to the arithmetic progression according to the vehicle demand power A, a delay time T is set, and within the delay time T, the electric power converted by the engine output power is integrated to obtain the electric power. When the power output of the engine (2) is greater than the power required by the vehicle, and the difference between the output power of the engine (2) and the average power required A of the vehicle is less than the arithmetic constant K, the output power of the engine (2) remains unchanged after the delay time T ends; when the power output of the engine (2) is less than or equal to the average power required by the vehicle system within the delay time T, or when the difference between the output power of the engine (2) and the average power required A of the vehicle is greater than or equal to the arithmetic constant K, the output power of the engine (2) changes to a value of the nearest arithmetic array greater than or equal to the average power required A of the vehicle within the time T after the delay time T ends; When the power output device (7) has output, the engine operating point is set to a delay time T when it moves according to the vehicle power demand B in an arithmetic progression. During the delay time T, when the output power of the engine (2) is greater than the average power demand B of the vehicle, and when the difference between the output power of the engine (2) and the average power demand B of the vehicle during the time T is less than the arithmetic constant K, the output power of the engine (2) remains unchanged after the delay time T ends. During the time T, when the power output of the engine (2) is less than or equal to the average power demand of the vehicle system, or when the difference between the output power of the engine (2) and the vehicle power demand B is greater than or equal to the arithmetic constant K, after the delay time T ends, the output power of the engine (2) changes to a value greater than or equal to the nearest arithmetic progression of the vehicle power demand B.

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