A full-time intelligent four-wheel drive system suitable for new energy tractor

Abstract

Embodiments of the application disclose a full-time intelligent four-wheel drive system suitable for new energy tractors. The system is characterized in that a hybrid transmission is connected with an engine, a driving end of a first clutch is connected with an output end of the hybrid transmission through a gear transmission mechanism, a driven end of the first clutch is connected with a front axle, a driving end of a second clutch is connected with a third motor, a driven end of the second clutch is connected with the front axle, a vehicle controller calculates a differential rotation rate of front wheels and rear wheels according to rotation signals of the front axle and the rear axle detected by first and second rotation sensors, and controls engagement and disengagement of the first and second clutches in combination with a vehicle speed signal and an engine load signal, so that the four-wheel drive system is switched between a mechanical four-wheel drive mode, an electric four-wheel drive mode and a two-wheel drive mode. The full-time intelligent four-wheel drive system suitable for new energy tractors avoids the defects of low efficiency and high heat generation of a pure electric drive four-wheel drive system under heavy load working conditions.

Description

Technical Field

[0001] This invention relates to the field of tractor four-wheel drive system technology, and specifically to a full-time intelligent four-wheel drive system suitable for new energy tractors. Background Technology

[0002] In related technologies, the four-wheel drive system used in tractors is a mechanical transmission system with a fixed differential speed between the front and rear axles. This system has the characteristic of high transmission efficiency. In order to allow the front axle to exert greater traction force when working in the field, a large front wheel lead ratio is generally designed. However, in working scenarios with small traction loads, the excessive front wheel lead ratio causes severe tire wear and high internal friction between the front and rear axles.

[0003] Some agricultural machinery manufacturers and the automotive industry have proposed a front and rear axle distributed drive system for new energy tractors. The front and rear axles have their own independent motor drives. This solution achieves full-time dynamic differential speed and solves the shortcomings of the above structure. However, due to the low efficiency of the electric drive system, it suffers from high losses and high heat generation when the tractor is working under heavy load in the field, making it unsuitable for tractor operating conditions. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose an all-time intelligent four-wheel drive system suitable for new energy tractors that avoids the defects of low efficiency and high heat generation under heavy load conditions.

[0006] The all-time intelligent four-wheel drive system for new energy tractors according to embodiments of the present invention includes an engine, a hybrid transmission, a rear axle, a first clutch, a front axle, a second clutch, a third motor, a first speed sensor, a transfer case, a second speed sensor, a vehicle controller, a first motor, and a second motor. The hybrid transmission is connected to the engine, and its output is connected to the rear axle. The driving end of the first clutch is connected to the output of the hybrid transmission via a gear transmission mechanism, and its driven end is connected to the front axle. The driving end of the second clutch is connected to the third motor, and its driven end is connected to the front axle. The first speed sensor is located in the transfer case and outputs to the front axle. The drive shaft of the axle is used to detect the front axle speed in real time. The second speed sensor is located on the drive shaft from the hybrid transmission to the rear axle to detect the rear axle speed in real time. The vehicle controller is electrically connected to the first motor, the second motor, the third motor, the first clutch, the second clutch, the first speed sensor, and the second speed sensor. The vehicle controller is configured to: calculate the front wheel and rear wheel differential speed based on the speed signals of the front axle and the rear axle detected by the first speed sensor and the second speed sensor, and control the engagement and disengagement of the first clutch and the second clutch in combination with the vehicle speed signal and the engine load signal, so that the four-wheel drive system can switch between mechanical four-wheel drive mode, electric four-wheel drive mode, and two-wheel drive mode.

[0007] The all-time intelligent four-wheel drive system for new energy tractors in this invention solves the problem of severe tire wear and internal friction caused by excessive front wheel lead ratio in traditional mechanical four-wheel drive systems. Through real-time differential rate adjustment, the front and rear wheel speeds are always matched, significantly reducing tire wear and power loss within the transmission system. Secondly, the all-time intelligent four-wheel drive system for new energy tractors in this invention avoids the shortcomings of low efficiency and high heat generation in pure electric four-wheel drive systems under heavy load conditions. During heavy-load operations, it primarily relies on the mechanical system to transmit power, ensuring high transmission efficiency and avoiding the risk of motor overheating.

[0008] In some embodiments, in the electric four-wheel drive mode, the first clutch is disengaged, the second clutch is engaged, the first motor or the second motor is configured as a generator, a portion of the engine power is output to the rear axle via the hybrid transmission, and another portion of the engine power is generated by the first motor or the second motor and then transmitted to the third motor so that the third motor drives the front axle. The vehicle controller dynamically adjusts the output power of the third motor according to the differential rate.

[0009] In some embodiments, in the mechanical four-wheel drive mode, the first clutch is engaged, the second clutch is disengaged, and the engine power is divided into a first path and a second path after passing through the hybrid transmission. In the first path, the engine power is transmitted to the rear axle, and in the second path, the engine power is transmitted to the front axle.

[0010] In some embodiments, in the two-wheel drive mode, both the first clutch and the second clutch are disengaged, and the front axle follows.

[0011] In some embodiments, the all-time intelligent four-wheel drive system for new energy tractors of the present invention further includes a front axle double speed steering mode. In the front axle double speed steering mode, the vehicle controller is configured to: when receiving a front axle double speed steering mode command and the current steering wheel angle exceeds a preset steering angle threshold, the vehicle controller controls the third motor to temporarily increase the front wheel lead rate, and the front axle drags the tractor to turn in order to reduce the turning radius.

[0012] In some embodiments, in the front axle double speed steering mode, the vehicle controller can also be used in conjunction with automatic single-sided rear wheel braking to reduce the turning radius.

[0013] In some embodiments, the vehicle controller is further configured to: when an emergency braking signal is detected, the vehicle controller controls the first clutch to engage to distribute braking force to the four front and rear tires.

[0014] In some embodiments, the vehicle controller is further configured to: when the vehicle speed is higher than a preset high-speed threshold, the vehicle controller controls the second clutch to disengage to separate the third motor from the front axle.

[0015] In some embodiments, the all-time intelligent four-wheel drive system for new energy tractors of the present invention further includes a reducer, the reducer being connected to the output end of the third motor, and the output end of the reducer being connected to the driving end of the second clutch.

[0016] In some embodiments, the four-wheel drive system may be applied to a parallel hybrid tractor, a series hybrid tractor, or a pure electric tractor. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an all-time intelligent four-wheel drive system applicable to new energy tractors according to an embodiment of the present invention.

[0018] Figure label: 1. Engine; 2. Hybrid transmission; 3. Rear axle; 4. First clutch; 5. Front axle; 6. Second clutch; 7. Third motor; 8. First speed sensor; 9. Second speed sensor; 10. Second motor; 11. First motor. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] like Figure 1 As shown, the all-time intelligent four-wheel drive system for new energy tractors according to this embodiment of the invention includes an engine 1, a hybrid transmission 2, a rear axle 3, a first clutch 4, a front axle 5, a second clutch 6, a third motor 7, a first speed sensor 8, a transfer case, a second speed sensor 9, a vehicle controller, a first motor 11, and a second motor 12. The hybrid transmission 2 is connected to the engine 1, and its output end is driven by the rear axle 3. The driving end of the first clutch 4 is connected to the output end of the hybrid transmission 2 via a gear transmission mechanism, and its driven end is connected to the front axle 5. The driving end of the second clutch 6 is connected to the third motor 7, and its driven end is driven by the front axle 5. The first speed sensor 8 is located at the output of the transfer case. A second speed sensor 9 is located on the drive shaft from the hybrid transmission 2 to the rear axle 3 for real-time detection of the front axle 5 speed. The vehicle controller is electrically connected to the first motor 11, the second motor 12, the third motor 7, the first clutch 4, the second clutch 6, the first speed sensor 8, and the second speed sensor 9. The vehicle controller is configured to calculate the front wheel and rear wheel differential rate based on the speed signals of the front axle 5 and the rear axle 3 detected by the first speed sensor 8 and the second speed sensor 9, and, in conjunction with the vehicle speed signal and the engine 1 load signal, control the engagement and disengagement of the first clutch 4 and the second clutch 6 to switch the four-wheel drive system between mechanical four-wheel drive mode, electric four-wheel drive mode, and two-wheel drive mode.

[0021] Exemplarily, the all-time intelligent four-wheel drive system for new energy tractors in this embodiment of the invention achieves flexible switching of the front axle 5's drive mode through the coordinated control of the first clutch 4, the second clutch 6, and the third motor 7. Part of the power output from the engine 1 and the hybrid transmission 2 is directly transmitted to the front axle 5 via the gear transmission mechanism and the first clutch 4, forming a purely mechanical four-wheel drive mode. The other part, when the second clutch 6 is engaged, allows the power from the third motor 7 to be transmitted to the front axle 5 via the transfer case, forming an electric four-wheel drive mode. The vehicle controller collects real-time speed sensor signals from the front axle 5 and rear axle 3, calculates the precise front and rear wheel differential rate, and, combined with operating condition data such as vehicle speed and engine load, intelligently decides whether to engage or disengage the first clutch 4 and the second clutch 6. During heavy-load field operations, the system maintains the mechanical four-wheel drive mode, utilizing high transmission efficiency to exert great traction. During light-load or road driving, it automatically switches to two-wheel drive mode or electric four-wheel drive mode, thereby achieving intelligent adjustment of the dynamic differential rate at all times.

[0022] Compared with related technologies, the all-time intelligent four-wheel drive system for new energy tractors in this invention solves the problem of severe tire wear and internal friction caused by excessive front wheel lead rate in traditional mechanical four-wheel drive systems. Through real-time differential rate adjustment, the front and rear wheel speeds are always matched, significantly reducing tire wear and power loss within the transmission system. Secondly, the all-time intelligent four-wheel drive system for new energy tractors in this invention avoids the shortcomings of low efficiency and high heat generation in pure electric four-wheel drive systems under heavy load conditions. During heavy-load operations, it primarily relies on the mechanical system to transmit power, ensuring high transmission efficiency and avoiding the risk of motor overheating.

[0023] In some embodiments, in electric four-wheel drive mode, the first clutch 4 is disengaged, the second clutch 6 is engaged, the first motor 11 or the second motor 12 is configured as a generator, a portion of the power of the engine 1 is output to the rear axle 3 via the hybrid transmission 2, and another portion of the power of the engine 1 is generated by the first motor 11 or the second motor 12 and then transmitted to the third motor 7 so that the third motor 7 drives the front axle 5. The vehicle controller dynamically adjusts the output power of the third motor 7 according to the differential rate.

[0024] For example, such as Figure 1 As shown, in electric four-wheel drive mode, the first clutch 4 is disengaged and the second clutch 6 is engaged. The power of engine 1 is output in two paths through the hybrid transmission 2. One part directly drives the rear axle 3, and the other part is converted into electrical energy by the first motor 11 or the second motor 12 to supply the third motor 7 to drive the front axle 5. The vehicle controller dynamically adjusts the output power of the third motor 7 based on the real-time differential speed ratio of the front axle 5 and the rear axle 3 calculated by the first and second speed sensors 9, so that the front wheels and rear wheels always maintain the optimal speed ratio relationship, realizing full-time continuously variable differential control.

[0025] The all-time intelligent four-wheel drive system for new energy tractors in this embodiment of the invention uses a hybrid architecture that mechanically drives the rear axle 3 and electrically drives the front axle 5. This removes the constraint of a fixed front wheel lead ratio, reducing tire wear and transmission system internal losses. Simultaneously, under light load conditions, excess power from the engine 1 can be converted into electrical energy to drive the front axle 5, avoiding the energy waste caused by the fixed transmission ratio in traditional mechanical four-wheel drive. Under heavy load conditions, it switches back to mechanical mode to ensure efficient transmission.

[0026] In some embodiments, in mechanical four-wheel drive mode, the first clutch 4 is engaged and the second clutch 6 is disengaged. The power of engine 1 is divided into a first path and a second path after passing through the hybrid transmission 2. In the first path, the power of engine 1 is transmitted to the rear axle 3, and in the second path, the power of engine 1 is transmitted to the front axle 5.

[0027] For example, in mechanical four-wheel drive mode, the first clutch 4 is engaged and the second clutch 6 is disengaged. The output power of engine 1 is divided into two paths after passing through the hybrid transmission 2. The first path is directly transmitted to the rear axle 3, and the second path is transmitted to the front axle 5 through the gear transmission mechanism and the first clutch 4. At this time, both the front axle 5 and the rear axle 3 are driven by engine 1 through mechanical paths, forming a rigid mechanical four-wheel drive structure with a fixed transmission ratio. The vehicle controller no longer intervenes in differential speed adjustment, and the system is in a traditional mechanical all-wheel drive state.

[0028] The mechanical four-wheel drive mode of the all-time intelligent four-wheel drive system for new energy tractors in this embodiment of the invention fully leverages the advantages of high efficiency and reliability of mechanical transmission, making it suitable for heavy-duty field operations and other high-traction conditions. Engine 1 power is directly transmitted to the front axle 5 and rear axle 3 via gears, avoiding energy conversion losses and heat generation issues in the electric transmission system, ensuring stable driving force and longer continuous operating time in scenarios such as deep plowing and heavy-load traction. Simultaneously, the mechanical four-wheel drive mode, as the basic drive solution, complements the electric four-wheel drive mode, enabling the system to intelligently switch between high-efficiency and flexible ranges, balancing overall vehicle performance and fuel economy under different operating conditions.

[0029] In some embodiments, in two-wheel drive mode, both the first clutch 4 and the second clutch 6 are disengaged, and the front axle 5 moves accordingly.

[0030] Specifically, in two-wheel drive mode, both the first clutch 4 and the second clutch 6 are disengaged. The power of the engine 1 is transmitted to the rear axle 3 through the hybrid transmission 2 to drive the rear wheels to rotate. The front axle 5 is completely disconnected from the power system and only acts as a follower wheel, rolling freely in the direction of the vehicle's travel, without participating in driving.

[0031] The two-wheel drive mode eliminates the drive load on the front axle, thus eliminating tire wear and transmission system losses caused by front wheel lead. In road transport and light-load transfer scenarios, it can reduce overall vehicle drag and energy consumption, improve fuel economy, and reduce tire wear.

[0032] In some embodiments, the all-time intelligent four-wheel drive system for new energy tractors of the present invention further includes a front axle 5x speed steering mode. In the front axle 5x speed steering mode, the vehicle controller is configured to: when it receives a front axle 5x speed steering mode command and the current steering wheel angle exceeds a preset steering angle threshold, the vehicle controller controls the third motor 7 to temporarily increase the front wheel lead rate, and the front axle 5 drags the tractor to turn in order to reduce the turning radius.

[0033] Specifically, in the 5x speed steering mode of the front axle, when the vehicle controller receives a mode command and detects that the steering wheel angle exceeds a preset threshold, it will control the third motor 7 to temporarily increase the drive speed of the front axle 5, significantly increasing the front wheel lead rate. At this time, the front axle 5 is actively driven by the third motor 7, forming a faster driving speed than the rear axle 3, thereby enabling the front axle 5 to drive the entire vehicle to complete a sharp turn and reduce the turning radius.

[0034] The 5x speed steering mode on the front axle solves the problem of difficult steering for new energy tractors in small spaces such as fields, narrow plots, or orchards. By temporarily overspeeding the electric front axle, the tractor can achieve a smaller turning radius than traditional mechanical steering, improving the maneuverability and operational flexibility of implements in complex terrain.

[0035] In some embodiments, in the 5x speed steering mode on the front axle, the vehicle controller can also be used in conjunction with automatic single-sided rear wheel braking to reduce the turning radius.

[0036] In the 5x front axle steering mode, the vehicle controller combines the temporary increase in front wheel lead rate by the third motor 7 with automatic single-sided rear wheel braking. When the steering wheel angle exceeds a preset threshold, the system increases the drive speed of the front axle 5 while automatically applying appropriate braking force to the rear wheel on the inside of the turn, causing the rear axle 3 to produce a differential steering effect. The active towing of the front axle 5 and the single-sided braking of the rear axle 3 work together to propel the tractor to turn more closely around the steering center, further breaking through the physical steering limits and significantly reducing the turning radius compared to the pure 5x front axle steering mode. This is especially suitable for maneuvering needs in extremely narrow spaces such as U-turns at field ends and inside sheds.

[0037] In some embodiments, the vehicle controller is further configured to: when an emergency braking signal is detected, control the first clutch 4 to engage to distribute braking force to the four front and rear tires.

[0038] Specifically, when the vehicle controller detects an emergency braking signal, such as when the brake pedal depth exceeds a preset threshold or the braking acceleration exceeds a safety limit, it controls the first clutch 4 to engage, mechanically connecting the front axle 5 to the output of the hybrid transmission 2. At this time, the braking torque that was originally only applied to the rear axle 3 is transmitted to the front axle 5 through the transmission system, thus enabling all four wheels to brake simultaneously. This fully utilizes the dynamic transfer effect of the curb weight during braking, improving the safety and stability of the new energy tractor under emergency braking conditions. Simultaneous braking of all four wheels shortens the braking distance and prevents the risk of rear-end skidding or fishtailing that might occur due to braking only the rear wheels, with particularly significant advantages in low-traction scenarios such as wet roads or sloping terrain.

[0039] In some embodiments, the vehicle controller is further configured to: when the vehicle speed is higher than a preset high-speed threshold, the vehicle controller controls the second clutch 6 to disengage to separate the third motor 7 from the front axle 5.

[0040] Specifically, when the vehicle speed exceeds the preset high-speed threshold, the vehicle controller actively disconnects the second clutch 6, completely disengaging the third motor 7 from the front axle 5 transmission system, so that the front axle 5 returns to a follow-up state and is no longer driven or dragged by the motor.

[0041] In pure electric four-wheel drive or assisted drive mode, the speed of the front axle motor 5 needs to be matched with the speed of the front wheels in real time. If the vehicle speed is too high, the motor may experience bearing wear, winding overheating, or even mechanical disintegration due to excessive speed. After forced disengagement, the motor stops or only maintains a low speed, which protects the motor and transmission system, reduces the additional energy loss and noise interference caused by motor back drag during high-speed driving, and improves the vehicle's high-speed range and reliability.

[0042] In some embodiments, the all-time intelligent four-wheel drive system for new energy tractors of the present invention further includes a reducer, the reducer being connected to the output end of the third motor 7, and the output end of the reducer being connected to the driving end of the second clutch 6.

[0043] Specifically, the reducer is installed between the output end of the third motor 7 and the driving end of the second clutch 6. The high-speed, low-torque power output by the third motor 7 is reduced in speed and increased in torque by the reducer, and then transmitted to the front axle 5 drive system through the second clutch 6. The vehicle controller still controls the engagement and disengagement of the clutch according to the aforementioned strategy, while the reducer, as an intermediate link with a fixed transmission ratio, always participates in the power transmission of the electric drive path.

[0044] The all-time intelligent four-wheel drive system for new energy tractors in this embodiment of the invention, by incorporating a reducer, allows the third motor 7 to operate in a higher speed range, fully utilizing the power density advantage of the motor at high speeds. Simultaneously, it provides sufficient driving torque to the front axle 5 to meet the demands of heavy-load conditions such as field operations or hill starts. Furthermore, the combination of the motor and reducer allows for greater torque output without increasing the motor's size, helping to save layout space and reduce system costs. The reducer also buffers fluctuations in the motor's output torque, resulting in smoother transmission of driving force to the front axle 5 and reducing damage to transmission components from impacts.

[0045] In some embodiments, the four-wheel drive system may be applied to a parallel hybrid tractor, a series hybrid tractor, or a pure electric tractor.

[0046] For example, the all-time intelligent four-wheel drive system of this embodiment of the invention serves as a modular drive platform that can be adapted to the power topology of different new energy tractors. In a parallel hybrid tractor, the first motor 11 and the second motor 12 can function as either a drive motor or a generator, respectively, working in conjunction with the engine 1 for output. In a series hybrid tractor, the engine 1 supplies power to the motors only through the generator, and the drive motors directly drive the rear axle 3. In a pure electric tractor, the engine 1 and the hybrid gearbox 2 are removed, and the rear axle 3 is directly driven by the first motor 11 and the second motor 12, while the third motor 7 continues to drive the front axle 5 according to the original strategy.

[0047] In some embodiments, when the vehicle speed is lower than a preset low-speed threshold, the power of the third motor 7 accounts for a lower proportion of the output power of the engine 1 than a preset proportion threshold, and the differential speed of the front and rear wheels is close to zero, the vehicle controller controls the four-wheel drive system to enter the electric four-wheel drive mode.

[0048] Specifically, when the vehicle speed is below a preset low-speed threshold, the power ratio of the third motor 7 is below a preset proportional threshold, and the differential slip ratio between the front and rear wheels is close to zero, the vehicle controller determines that the current operating condition is suitable for switching to electric four-wheel drive mode. It then controls the first clutch 4 to disengage and the second clutch 6 to engage, switching the drive of the front axle 5 from a mechanical path to an electric path driven by the third motor 7. At this time, the four-wheel drive system enters a hybrid drive state where the third motor 7 independently drives the front axle 5, and the engine 1 independently drives the rear axle 3.

[0049] Under low-speed, light-load conditions, the differential slip ratio is close to zero, meaning the front wheels don't need to lead excessively, and the fixed transmission ratio of mechanical four-wheel drive would actually waste energy. After switching to electric four-wheel drive, the third motor 7 can precisely adjust the speed of the front axle 5 as needed, ensuring that the front and rear wheel speeds are always matched, significantly reducing tire wear and improving transmission efficiency.

[0050] In some embodiments, when the vehicle speed is lower than a preset low speed threshold, the total load rate of engine 1 increases, the power of the third motor 7 accounts for a higher proportion of the output power of engine 1 than a preset ratio threshold, and the differential rate between the front and rear wheels is greater than a preset differential rate threshold, the vehicle controller controls the four-wheel drive system to enter the mechanical four-wheel drive mode.

[0051] Specifically, when the vehicle speed is lower than the preset low-speed threshold, the total load rate of engine 1 increases, the power of the third motor 7 accounts for a higher proportion of the output power of engine 1 than the preset proportion threshold, and the differential rate between the front and rear wheels is greater than the preset differential rate threshold, the vehicle controller determines that the current electric drive system is approaching its efficiency or power limit. It then controls the first clutch 4 to engage and the second clutch 6 to disengage, switching the drive of the front axle 5 from the electric path to the mechanical path. At this time, the four-wheel drive system enters a pure mechanical four-wheel drive mode where the power of engine 1 drives the front axle 5 and the rear axle 3 simultaneously through the hybrid transmission 2. This avoids the problems of low efficiency and high heat generation in the electric four-wheel drive mode under heavy load conditions. When the load of engine 1 increases and the proportion of electric drive power is too high, the energy conversion loss and motor heat generation in the electric transmission link will increase significantly. Switching to mechanical four-wheel drive at this time can make full use of the high efficiency of gear transmission, ensuring that the maximum traction and continuous working capability are obtained in heavy-load field operations.

[0052] In some embodiments, when the vehicle speed is higher than a preset high speed threshold, the vehicle controller controls the four-wheel drive system to enter two-wheel drive mode.

[0053] When the vehicle speed exceeds the preset high-speed threshold, the vehicle controller determines that the current operating condition has entered the medium-to-high-speed driving stage. It then controls both the first clutch 4 and the second clutch 6 to disengage, completely disconnecting the front axle 5 from the power system, causing the front axle 5 to switch to a follow-up state. At this time, the power of the engine 1 is transmitted to the rear axle 3 only through the hybrid transmission 2, driving the rear wheels to drive independently. The system enters a two-wheel drive mode with pure rear axle 3 drive.

[0054] In high-speed driving scenarios, the vehicle's energy economy is improved. After the front axle 5 disengages from drive, the internal friction of the transmission system and tire wear caused by the front wheel differential are eliminated. At the same time, the idling loss and overspeed risk of the third motor 7 and its transmission mechanism at high speeds are avoided. In two-wheel drive mode, the vehicle's driving resistance is reduced, which is beneficial to improving the driving range and fuel economy, and is especially suitable for high-speed light-load conditions such as road transportation and unloaded transfer.

[0055] In some specific embodiments, the four-wheel drive system can operate in multiple modes depending on the load, differential rate, and vehicle speed: 1. Dynamic four-wheel drive mode When the vehicle speed is low (generally below 20 km / h), the power of the third motor 7 accounts for a low proportion of the engine 1's output power (generally below 30%), and the front-rear wheel differential is close to 0, the system is in dynamic four-wheel drive mode. At this time, the second clutch 6 engages, the first clutch 4 disengages, and a portion of the engine 1's power is directly output to the rear axle 3 after passing through the hybrid transmission 2. The remaining power is generated by the first motor 11 or the second motor 12 acting as a generator and then transmitted to the third motor 7. The third motor 7 then drives the front axle 5 after deceleration. The vehicle controller can dynamically adjust the output power of the third motor 7 based on the speed signals from the first speed sensor 8 and the second speed sensor 9, ensuring that the front axle 5 effectively outputs traction while reducing internal friction between the front and rear axles 3 and minimizing tire wear. Although the power transmission path of the front axle 5 is electric, resulting in lower transmission efficiency, the proportion of the front axle 5's power to the engine 1's output power is low, leading to less power loss.

[0056] 2. Mechanical four-wheel drive mode When the vehicle speed is low (generally below 20km / h), the total load rate of engine 1 increases, the power of the third motor 7 accounts for a high proportion of the output power of engine 1 (generally above 30%), and the front and rear wheel differential rate is large (generally above 3%), the system is in mechanical four-wheel drive mode. At this time, the first clutch 4 is engaged, the second clutch 6 is disengaged, and the power of engine 1 is divided into two paths after passing through the hybrid transmission 2. One path is transmitted to the rear axle 3, and the other path is transmitted directly to the front axle 5 through gears and the first clutch 4. At this time, the power transmission path of the front axle 5 is mechanical transmission, which is more efficient and has less power loss.

[0057] 3. Two-wheel drive transportation mode When the vehicle speed is high (generally above 20km / h), both the first clutch 4 and the second clutch 6 are disengaged. At this time, the front axle 5 is fully engaged, minimizing tire wear.

[0058] 4. Front axle 5x speed steering mode When a temporary increase in steering capability and a reduction in turning radius are needed during field operations, this mode can be activated. When activated, if the current steering wheel angle exceeds a specified angle, the vehicle controller will control the third motor 7 to temporarily increase the front wheel lead ratio to over 100%, forcibly steering the vehicle by the front wheels to reduce the turning radius. This function can be used in conjunction with automatic single-sided rear wheel braking to further reduce the turning radius.

[0059] 5. Other special working conditions Safety protection for the third motor 7: Because the third motor 7 requires a large reduction ratio to amplify torque and drive the front axle 5, at high vehicle speeds, the front axle 5 will drag the third motor 7 to extremely high speeds, causing the motor to run away. Therefore, a second clutch 6 must be installed. At high vehicle speeds, the second clutch 6 will disengage, separating the third motor 7 from the front axle 5 and protecting the motor.

[0060] Four-wheel braking: During emergency braking, regardless of the vehicle speed, the first clutch 4 will engage, distributing braking force to all four tires and improving braking performance.

[0061] 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," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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.

[0062] 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 at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0063] 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 mechanical connection, an electrical connection, or a connection that allows communication between them; 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, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0064] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0065] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0066] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A full-time intelligent four-wheel drive system suitable for new energy tractors, characterized in that, include: Engine (1); A hybrid transmission (2) and a rear axle (3), wherein the hybrid transmission (2) is connected to the engine (1), and the output end of the hybrid transmission (2) is driven to the rear axle (3); The first clutch (4) and the front axle (5) are connected. The driving end of the first clutch (4) is connected to the output end of the hybrid gearbox (2) through a gear transmission mechanism, and the driven end of the first clutch (4) is connected to the front axle (5). The second clutch (6) and the third motor (7) are connected, with the driving end of the second clutch (6) connected to the third motor (7) and the driven end of the second clutch (6) connected to the front axle (5). The first speed sensor (8) and the transfer case are provided. The first speed sensor (8) is located on the drive shaft of the transfer case that outputs to the front axle (5) for real-time detection of the speed of the front axle (5). The second speed sensor (9) is located on the drive shaft from the hybrid transmission (2) to the rear axle (3) for real-time detection of the speed of the rear axle (3); The vehicle controller is electrically connected to the first motor (11), the second motor (12), the third motor (7), the first clutch (4), the second clutch (6), the first speed sensor (8), and the second speed sensor (9), respectively. The vehicle controller is configured to calculate the front wheel and rear wheel differential rate based on the speed signals of the front axle (5) and the rear axle (3) detected by the first speed sensor (8) and the second speed sensor (9), and control the engagement and disengagement of the first clutch (4) and the second clutch (6) in combination with the vehicle speed signal and the engine (1) load signal, so that the four-wheel drive system can switch between mechanical four-wheel drive mode, electric four-wheel drive mode and two-wheel drive mode.

2. The all-time intelligent four-wheel drive system for new energy tractors according to claim 1, characterized in that, In the electric four-wheel drive mode, the first clutch (4) is disengaged, the second clutch (6) is engaged, the first motor (11) or the second motor (12) is configured as a generator, a portion of the power of the engine (1) is output to the rear axle (3) via the hybrid transmission (2), and another portion of the power of the engine (1) is generated by the first motor (11) or the second motor (12) and then transmitted to the third motor (7) so that the third motor (7) drives the front axle (5). The vehicle controller dynamically adjusts the output power of the third motor (7) according to the differential rate.

3. The all-time intelligent four-wheel drive system for new energy tractors according to claim 1, characterized in that, In the mechanical four-wheel drive mode, the first clutch (4) is engaged and the second clutch (6) is disengaged. The power of the engine (1) is divided into a first path and a second path after passing through the hybrid transmission (2). In the first path, the power of the engine (1) is transmitted to the rear axle (3), and in the second path, the power of the engine (1) is transmitted to the front axle (5).

4. The all-time intelligent four-wheel drive system for new energy tractors according to claim 1, characterized in that, In the two-wheel drive mode, both the first clutch (4) and the second clutch (6) are disengaged, and the front axle (5) moves accordingly.

5. The all-time intelligent four-wheel drive system for new energy tractors according to claim 1, characterized in that, It also includes a front axle (5) double speed steering mode. In the front axle (5) double speed steering mode, the vehicle controller is configured to: when it receives the front axle (5) double speed steering mode command and the current steering wheel angle exceeds the preset steering angle threshold, the vehicle controller controls the third motor (7) to temporarily increase the front wheel lead rate, and the front axle (5) drags the tractor to turn so as to reduce the turning radius.

6. The all-time intelligent four-wheel drive system for new energy tractors according to claim 5, characterized in that, In the front axle (5) speed steering mode, the vehicle controller can also be used in conjunction with automatic single-sided rear wheel braking to reduce the turning radius.

7. The all-time intelligent four-wheel drive system for new energy tractors according to claim 1, characterized in that, The vehicle controller is also configured to: when an emergency braking signal is detected, the vehicle controller controls the first clutch (4) to engage to distribute braking force to the front and rear four tires.

8. The all-time intelligent four-wheel drive system for new energy tractors according to claim 1, characterized in that, The vehicle controller is also configured to: when the vehicle speed is higher than a preset high speed threshold, the vehicle controller controls the second clutch (6) to disengage to separate the third motor (7) from the front axle (5).

9. The all-time intelligent four-wheel drive system for new energy tractors according to claim 1, characterized in that, It also includes a speed reducer, which is connected to the output end of the third motor (7) and the output end of the speed reducer is connected to the driving end of the second clutch (6).

10. The all-time intelligent four-wheel drive system for new energy tractors according to any one of claims 1-9, characterized in that, The four-wheel drive system can be applied to parallel hybrid tractors, series hybrid tractors, or pure electric tractors.

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