A cruise control system and method for a series hybrid tractor

Abstract

The present invention discloses a constant speed cruise control system and method for a series hybrid tractor. The method includes: the vehicle controller obtains the operating information of the tractor and determines whether it can enter the constant speed cruise state; if the operating information meets the preset constant speed cruise conditions, the cruise enable switch is activated to enter the constant speed cruise state, and the current vehicle speed is used as the cruise speed; when in the constant speed cruise state, the vehicle controller receives an operation trigger signal from the driver operating system to adjust the cruise speed, reset the cruise speed, and exit the constant speed cruise state; when the power shift is started in the constant speed cruise state, the tractor remains in the constant speed cruise activation state, so that the tractor can continue to perform constant speed cruise in the opposite direction after the power shift. This application improves the operation efficiency of the tractor through constant speed cruise, reduces the driving intensity of the driver, and can perform power shift in the constant speed cruise state, which is convenient for the tractor to turn around during operation.

Description

Technical Field

[0001] The present invention belongs to the field of drive control of hybrid tractors, and particularly relates to a constant speed cruise control system and method for a series hybrid tractor. Background Art

[0002] Tractors are important tools in agricultural mechanized production. Traditional internal combustion engine-driven tractors require dozens of different gears to meet the power requirements of different tractor operating conditions. Series hybrid tractors are driven by electric motors, and the load speed curve of the electric motor can meet the vast majority of tractor operation conditions through two gears, reducing the driver's gear shifting burden and being conducive to fine tillage. To further reduce the driver's workload when plowing or performing other operations at a constant speed in the tractor field, it is particularly important for series hybrid tractors to achieve the function of constant speed cruise. Summary of the Invention

[0003] The purpose of the present invention is to provide a constant speed cruise control system and method for a series hybrid tractor, which can improve the tractor operation efficiency through constant speed cruise, reduce the driver's driving intensity, and can perform power reversal in the constant speed cruise state, facilitating the tractor to turn around during operation.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is: a constant speed cruise control system for a series hybrid tractor, including a series-connected engine, generator, and electric motor. The output end of the generator is connected to a power battery pack, and the output end of the electric motor is connected to the tractor drive system. It also includes a display system, a vehicle controller, and a driver operation system.

[0005] The engine, generator, electric motor, and power battery pack are respectively controlled by an engine management system EMS, a generator controller GCU, a motor controller MCU, and a battery management system BMC.

[0006] The drive system includes a two-speed gearbox, a rear axle, and wheels connected in sequence, for transmitting the power of the electric motor to the wheels.

[0007] The driver operation system includes a cruise switch group, an accelerator pedal, a brake pedal, a shift switch, and a direction switch; the driver realizes the constant speed cruise of the tractor by operating the driver operation system.

[0008] The display system is respectively connected to the engine management system EMS, the generator controller GCU, the motor controller MCU, and the battery management system BMC through the CAN bus for data interaction, and is used to display the driving state information of the tractor.

[0009] The vehicle controller is connected to the engine management system (EMS), generator controller (GCU), motor controller (MCU), and battery management system (BMC) via the CAN bus to obtain data information and send relevant control instructions. The vehicle controller is also connected to the driver operation system and the transmission via hardwiring to obtain the driver's operation information, and perform the determination of the cruise control state, the setting of the cruise control speed, and the control of the cruise control power output.

[0010] The cruise switch group includes a cruise enable switch, a cruise speed increase switch, and a cruise speed decrease switch; the direction switch includes a forward switch, a neutral switch, and a reverse switch.

[0011] A cruise control method for a series hybrid tractor specifically includes:

[0012] The vehicle controller obtains the operating information of the tractor and determines whether it can enter the cruise control state;

[0013] If the operating information meets the preset cruise control conditions, the cruise enable switch is activated to enter the cruise control state, and the current vehicle speed is used as the cruise speed; if not, the driving speed of the tractor is controlled by the accelerator pedal opening.

[0014] When in the cruise control state, the vehicle controller receives the operation trigger signal from the driver operation system and performs the adjustment of the cruise speed, the reset of the cruise speed, and the exit from the cruise control state.

[0015] When the power shift is started in the cruise control state, the tractor remains in the cruise control activation state, so that the tractor can continue to perform cruise control in the opposite direction after the power shift, which is convenient for the tractor to turn around during operation.

[0016] Further, the cruise control conditions refer to that the energy system operates normally, the transmission is not in neutral, the current driving speed is greater than the minimum threshold of the cruise speed, the brake switch is invalid, and the current driving direction is the forward direction are satisfied simultaneously.

[0017] Further, when the tractor is in the cruise control state, the vehicle controller determines to exit the cruise control state in any of the following situations: the cruise enable switch is not activated, the brake switch is effective, the transmission gear is in neutral, the direction switch is in neutral, or there is a driveline fault. The vehicle controller records the gear and cruise speed used in this cruise control and applies them during the cruise control reset operation.

[0018] Further, when the tractor is in the cruise control state, the driver presses the cruise speed increase switch and the cruise speed decrease switch simultaneously to perform the cruise speed reset operation. If the current gear is the same as the gear used in the previous cruise control, the target cruise speed is set to the previous cruise speed; otherwise, the cruise control state is exited.

[0019] Furthermore, the exit from the constant speed cruise state includes two modes: complete exit and incomplete exit. The complete exit is achieved by turning off the cruise enable switch; the incomplete exit is achieved by any of the following methods: stepping on the brake pedal, changing the gear of the transmission, or the direction switch being in the neutral position. In the incomplete exit mode, the cruise enable switch remains in the activated state, facilitating the reset operation of the cruise speed.

[0020] Furthermore, when the tractor is in the constant speed cruise state, the cruise speed is adjusted as follows: pressing the cruise speed increase switch or the cruise speed decrease switch controls the increase or decrease of the cruise speed respectively;

[0021] The vehicle control unit is set with the maximum cruise speed and the minimum cruise speed in the current gear. If the target cruise speed to be adjusted is higher than the maximum cruise speed, the vehicle control unit uses the maximum cruise speed for constant speed cruise. If the target cruise speed to be adjusted is lower than the minimum cruise speed, the vehicle control unit uses the minimum cruise speed for constant speed cruise.

[0022] Furthermore, when the tractor is in the constant speed cruise state, the vehicle control unit sets the cruise speed increase and decrease units corresponding to the respective gears according to different operating gears.

[0023] Furthermore, when the tractor is in the constant speed cruise state and the accelerator pedal is depressed so that the requested driving speed is greater than the current cruise speed, the vehicle control unit rapidly increases the driving speed according to the request signal of the accelerator pedal.

[0024] Furthermore, the power shift process of the tractor in the constant speed cruise state is as follows: when the cruise speed is less than 20 km / h and the direction switch changes direction, the vehicle control unit rapidly reduces the vehicle speed to 0 km / h by requesting reverse torque from the motor. At the same time, the vehicle control unit controls the generator enable to stop. Then, the vehicle control unit requests the motor speed mode and outputs torque with a limited torque to increase the motor speed to the constant speed cruise speed.

[0025] After the series hybrid tractor enters the constant speed cruise state, the vehicle control unit will request the motor to control the motor speed in a speed control manner to the motor speed corresponding to the requested constant speed cruise vehicle speed; the vehicle control unit will set the maximum and minimum output torques of the motor to ensure that the motor is not overloaded for a long time and guarantee system safety.

[0026] Adopting the above technical solutions, the present invention can achieve the following beneficial effects:

[0027] 1. This control system simplifies the system hardware and no longer requires the manual throttle of the internal combustion engine tractor for engine load control. It can achieve a fixed vehicle speed by only one or several key switches and maintain the vehicle speed even when the load suddenly decreases or increases.

[0028] 2. The cruise control system and control method of this application can be combined with the power shift technology of the tractor to quickly complete the turning operation of the tractor in the field. The driver can achieve a quick shift without operating the accelerator pedal and brake pedal, improving the operation efficiency and reducing the driving intensity.

[0029] 3. This application can maintain the current driving speed when the driver does not step on the accelerator pedal after the tractor reaches a specific vehicle speed and can exit the cruise control according to specific conditions; it reduces the complexity of the driver's operation to maintain the vehicle speed in the prior art, is beneficial to reducing the driver's workload, and ensures the tillage quality of the field. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a block diagram of the cruise control system of this application;

[0031] Figure 2 It is a control flowchart for cruise control state judgment and cruise speed setting of this application;

[0032] Figure 3 It is a control flowchart for increasing or decreasing the cruise speed of this application;

[0033] Figure 4 It is a control flowchart for the motor in the cruise control state of this application;

[0034] Figure 5 It is a control flowchart during the power shift process in the cruise control state of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following further describes the present invention in detail with reference to the drawings and specific embodiments.

[0036] As Figure 1 shown, this embodiment provides a cruise control system for a series hybrid tractor, including a vehicle controller (VCU), an engine, a generator, a motor, a power battery pack, a transmission system, a display system, and a driver operating system. The engine, generator, and motor are connected in series. The output end of the generator is connected to the power battery pack, and the output end of the motor is connected to the tractor transmission system. The transmission system includes a two-speed gearbox, a rear axle, and wheels connected in sequence, which is used to transmit the power of the motor to the wheels to realize vehicle operation.

[0037] The control system adopts a distributed control system. The engine, generator, motor and power battery pack are respectively controlled by an engine management system (EMS), a generator control unit (GCU), a motor control unit (MCU) and a battery management system (BMC). The control units of the above-mentioned main modules transmit data through a CAN bus. The engine, generator and power battery pack and their corresponding management systems constitute the energy system in the cruise control system of a series hybrid tractor.

[0038] The driver operation system includes a cruise switch group, an accelerator pedal, a brake pedal, a shift switch and a direction switch; the driver realizes the cruise control of the tractor by operating the driver operation system.

[0039] The display system is connected to the engine management system (EMS), the generator control unit (GCU), the motor control unit (MCU) and the battery management system (BMC) respectively through a CAN bus for data interaction, and is used to display the driving state information of the tractor.

[0040] The vehicle control unit (VCU) is connected to the engine management system (EMS), the generator control unit (GCU), the motor control unit (MCU) and the battery management system (BMC) through a CAN bus to obtain data information and send relevant control instructions; the vehicle control unit (VCU) is connected to the driver operation system and the gearbox through hard wires to obtain the driver's operation information, and executes the determination of the cruise control state, the setting of the cruise control speed and the control of the cruise control power output. The vehicle control unit (VCU) controls the cruise control by obtaining the data of the CAN bus and the hard wires connected.

[0041] Specifically, the vehicle control unit (VCU) serves as the main control unit of the entire control system, responsible for the detection of the vehicle state and the implementation of the cruise control algorithm. The vehicle control unit (VCU) can obtain the signal values of relevant signals in the driver operation system, and send control instructions or vehicle state data to other control units, as well as control the gear of the gearbox and obtain the current gear information. The vehicle control unit (VCU) obtains the data of each relevant control unit through the CAN bus, and realizes the control of the generator power generation, the motor torque and speed, etc. according to the states of other control units.

[0042] The vehicle control unit (VCU) is connected to the cruise switch group through hard wires. The cruise switch group includes: a cruise enable switch, a cruise speed increase switch and a cruise speed decrease switch. The driver can activate the cruise control state, increase or decrease the cruise speed, reset the cruise speed, etc. through this group of buttons.

[0043] The vehicle control unit (VCU) is connected to the accelerator pedal and the brake pedal by hard wires. It controls the output torque and speed of the motor by obtaining the opening of the accelerator pedal; it brakes the vehicle by obtaining the opening of the brake pedal, and then stops the motor drive and the generator power generation.

[0044] The vehicle control unit (VCU) is connected to the driving direction switch and the shift switch by hard wires. The direction switch includes a forward switch, a neutral switch, and a reverse switch. Operations such as setting the current running direction, stopping the machine, or power reversing can be performed through the direction switch; the gear of the gearbox can be changed through the shift switch, and the neutral gear can be achieved through special operations.

[0045] Furthermore, the engine is controlled by the engine management system EMS, which mainly processes engine-related signals, provides signals such as engine speed and torque to the vehicle control unit (VCU) through the CAN bus, and responds to the speed and torque request commands of the vehicle control unit (VCU).

[0046] The generator is controlled by the generator control unit GCU, which mainly outputs high-voltage current and voltage. The generator control unit responds to the torque request of the vehicle control unit (VCU), controls the output voltage and output current of the generator, and provides energy for the subsequent power battery pack and the operation of the motor.

[0047] The motor is controlled by the motor control unit MCU, and the motor drives the subsequent transmission system to make the vehicle run. The motor control unit MCU is used to respond to the torque request of the vehicle control unit (VCU) and drive the tractor to move forward or backward.

[0048] The power battery pack is controlled by the battery management system BMS, which mainly provides instantaneous energy supplementation for the acceleration or deceleration process of the tractor. The battery management system BMS responds to the on / off request of the power battery pack from the vehicle control unit (VCU).

[0049] The display system displays relevant information provided by the vehicle control unit (VCU), the engine management system EMS, the battery management system BMS, the generator control unit GCU, and the motor control unit MCU through the CAN bus. The driver can obtain driving state information such as whether the vehicle is in the cruise state and the cruise speed through this system.

[0050] This embodiment also provides a cruise control method for a series hybrid tractor. When the tractor driver is operating and needs to run at a constant speed, the cruise control switch can be activated. The vehicle control unit (VCU) determines whether it can enter the cruise control state based on information such as the engine, power battery pack, generator, motor, accelerator pedal, brake pedal, and transmission gear. If the current operating state of the tractor does not meet the cruise control conditions, the tractor cannot enter the cruise control to avoid safety problems or serious faults in the series hybrid tractor itself. If the current operating state of the tractor meets the cruise control setting conditions, the cruise enable switch is activated, and the vehicle control unit (VCU) will perform cruise control at the vehicle speed at the moment when the cruise enable switch is activated; after the driver releases the accelerator pedal or the request of the accelerator pedal cannot meet the cruise control vehicle speed, the vehicle control unit (VCU) will control the motor to continue running at the cruise speed.

[0051] In this embodiment, the control method for cruise control of a series hybrid tractor mainly includes four control processes, specifically: cruise control state judgment and cruise speed setting, cruise speed adjustment, motor control, and control of the power commutation process, as shown respectively in Figure 2 , Figure 3 , Figure 4 and Figure 5 respectively. The following will introduce the four control processes in detail with reference to the accompanying drawings.

[0052] As shown in Figure 2 , the methods for a series hybrid tractor to enter and exit the cruise control state include:

[0053] When the driver operates a series hybrid tractor and needs to perform cruise control at a certain speed during driving, the vehicle control unit (VCU) first needs to obtain the status of the energy system and determine whether the energy system functions normally. If the energy system cannot work properly, the cruise control setting will not be performed; if the energy system works normally, the vehicle control unit (VCU) will determine whether the current driving state is the cruise control state. If it is not the cruise control state, it will start to enter the cruise control state judgment process. If it is the cruise control state, it will enter the exit cruise control judgment process.

[0054] The vehicle control unit (VCU) determines whether the set cruise state is valid based on information such as whether the currently obtained cruise control state is valid, the current cruise enable switch state, the current driving speed, the brake switch state, and the driving direction state.

[0055] If the tractor is not in the cruise control state and the cruise enable switch is in the inactive state, and the driving state simultaneously meets the following conditions: the transmission is not in neutral, the current driving speed is greater than the minimum threshold of the cruise control speed, the brake switch is invalid, and the current driving direction is the forward direction, when the driver activates the cruise enable switch at this time, the series hybrid tractor enters the cruise control state and sets the current driving speed of the tractor as the cruise speed. If any one of the conditions is not met, entering the cruise control state is not allowed.

[0056] If the tractor is not in the cruise control state but the cruise enable switch is in the active state, if the current transmission gear is the same as the gear during the previous cruise control, the driver can simultaneously press the cruise speed increase switch and the cruise speed decrease switch combination button to reset the previous cruise control state. At this time, the set target cruise speed is the previous cruise speed, that is, directly use the previous cruise speed for cruise control and set the cruise control state to be valid; if the current transmission gear is different from the gear during the previous cruise control, then exit the current cruise control state judgment process.

[0057] If the tractor is in the cruise control state, the driver can exit the cruise state in any of the following ways: turn off the cruise enable switch, step on the brake pedal to make the brake switch valid, put the transmission in neutral, or set the direction switch to neutral. If a fault occurs in the drive system, the cruise control state will also be exited. After exiting the cruise control, the vehicle control unit (VCU) will continue to save the gear and cruise speed used in the previous cruise control to provide data support for cruise control reset.

[0058] Furthermore, the exit of the cruise control state includes two modes: complete exit and incomplete exit. The complete exit is achieved by turning off the cruise enable switch. The incomplete exit is achieved by any of the following methods: stepping on the brake pedal, changing the transmission gear, or the direction switch being in neutral. After completely exiting the cruise control, the driver needs to reactivate the cruise enable switch to enter the cruise control state again; in the incomplete exit mode, the cruise enable switch is still in the active state, and the driver can activate the cruise control state by simultaneously pressing the cruise speed increase and cruise speed decrease buttons and restore the previous cruise vehicle speed.

[0059] In the incomplete exit mode, after the driver exits the cruise control state, if they need to perform cruise control again at the current operating vehicle speed, they must first place the cruise enable switch in the inactive state and then reactivate the cruise enable switch to achieve this.

[0060] In addition, it should be noted that a two-speed gearbox is used in the transmission system of the present invention, and gear shifting is not performed during the constant speed cruise of the tractor. After activating the constant speed cruise, the vehicle control unit will record the current driving gear. If the current gear does not match the driving gear during driving, the system will exit the constant speed cruise state.

[0061] After the series hybrid tractor enters the constant speed cruise state, the driver can adjust the cruise speed according to Figure 3 as shown.

[0062] As Figure 3 shown, after the tractor enters the constant speed cruise state, the driver can use the cruise speed increase switch and the cruise speed decrease switch to adjust the cruise speed. The vehicle control unit (VCU) sets the maximum cruise speed and the minimum cruise speed in the current gear. If the target cruise speed to be adjusted is higher than the maximum cruise speed, the vehicle control unit (VCU) uses the maximum cruise speed for constant speed cruise; if the target cruise speed to be adjusted is less than the minimum cruise speed, the vehicle control unit (VCU) uses the minimum cruise speed for constant speed cruise. Moreover, the vehicle control unit (VCU) sets the cruise speed increase and decrease units corresponding to different operating gears. In this embodiment, the speed increase and decrease unit is 0.5 km / h in the field operation mode and 1 km / h in the road transportation mode. Of course, the vehicle control unit (VCU) can also set the vehicle speeds in different working condition modes such as plowing, rotary tillage, sowing or transportation to meet the best operating vehicle speeds of the tractor under different working conditions during field operations.

[0063] After the vehicle control unit (VCU) detects that the cruise speed increase switch is effective once, it will increase one speed unit according to the current gear, that is, the cruise speed is increased by 0.5 km / h in the field operation mode and the cruise speed is increased by 1 km / h in the road transportation mode; when the set target cruise speed is greater than the preset maximum cruise speed in the current gear, the maximum cruise speed of the current gear is used for constant speed cruise. After the vehicle control unit (VCU) detects that the cruise speed decrease switch is effective once, it will decrease one speed unit according to the current gear, that is, the cruise speed is decreased by 0.5 km / h in the field operation mode and the cruise speed is decreased by 1 km / h in the road transportation mode; when the set target cruise speed is less than the preset minimum cruise speed in the current gear, the minimum cruise speed of the current gear is used for constant speed cruise.

[0064] In this application, the vehicle control unit (VCU) is based on Figure 4The motor is controlled according to the following process. After entering the constant-speed cruise state, when the vehicle control unit (VCU) drives the motor in the constant-speed cruise mode, it simultaneously monitors the opening of the accelerator pedal. The vehicle control unit (VCU) determines whether the current driving speed is less than the set cruise speed. If it is less than the cruise speed, it drives according to the constant-speed cruise mode; if the driving speed requested by the accelerator pedal opening is greater than the cruise speed, the motor is driven mainly according to the accelerator pedal request to ensure vehicle acceleration; when the cruise state is invalid or the current driving speed is greater than the set cruise speed, the driving is also controlled by the accelerator pedal opening to meet the relevant driving requirements.

[0065] Based on the above motor control process, when the driver needs to quickly increase the driving speed, the accelerator pedal can be operated so that the requested driving speed is greater than the current cruise speed, and the vehicle control unit (VCU) will quickly increase the driving speed according to the request signal of the accelerator pedal. When the speed requested by the accelerator pedal is less than the cruise speed, the vehicle control unit (VCU) will return to the operation of the constant-speed cruise state and drive at the set speed.

[0066] When the series hybrid tractor performs a power reversal operation at the field head in the constant-speed cruise state, the vehicle control unit (VCU) is based on Figure 5 The following process controls the motor and the generator. When the series hybrid tractor is cruising at a constant speed and the cruise speed is less than 20 km / h, when the driver quickly toggles the direction switch to reverse the tractor, the vehicle control unit (VCU) requests a reverse torque from the motor to quickly reduce the vehicle speed of the tractor to 0 km / h. During this process, since the motor needs to output a reverse torque, the power battery pack will be charged, so it is necessary to stop the power generation operation of the generator at the start of the power reversal to avoid damage to the battery pack due to excessive charging current to the battery pack. After the speed of the tractor is reduced to 0 km / h, the vehicle control unit (VCU) requests the speed mode from the motor and quickly and smoothly increases the speed of the motor to the motor speed corresponding to the constant-speed cruise vehicle speed in a way that limits the torque output torque, so that the hybrid tractor completes the power reversal in the constant-speed cruise state. In this embodiment, the vehicle control unit (VCU) sets the maximum and minimum output torques of the motor to ensure that the motor is not overloaded for a long time and ensure system safety.

[0067] This control method is beneficial for the driver to quickly turn around at the end of the field and re-enter the field operation. That is to say, after activating the constant-speed cruise in the forward state of the tractor and performing a power reversal operation, the constant-speed cruise activation state can still be maintained in the reverse state, and the vehicle can reverse at the constant-speed cruise (or driver-configured) vehicle speed. After returning to the forward state through the power reversal, the constant-speed cruise is still in the activated state.

[0068] During the operation of the tractor, the turning operation is very frequent. By performing power shift under the constant speed cruise state, the driver can complete the turning of the tractor in the field only by operating the shift switch and the steering mechanism, without the need to additionally operate the brake pedal and the accelerator pedal. This makes the turning of the tractor during operation more convenient, helps to reduce the operation intensity of the driver, and improves the work efficiency.

[0069] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the inspiration of the thinking of the present invention shall be included within the scope of the protection of the rights of the present invention.

Claims

1. A constant speed cruise control system for a series hybrid tractor, characterized in that: It includes an engine, a generator, and a motor connected in series. The output terminal of the generator is connected to the power battery pack, and the output terminal of the motor is connected to the tractor transmission system. It also includes a display system, a vehicle controller, and a driver operation system; The engine, generator, motor, and power battery pack are respectively controlled by an engine management system EMS, a generator controller GCU, a motor controller MCU, and a battery management system BMC. The transmission system includes a second - gear gearbox, a rear axle, and wheels connected in sequence, which is used to transmit the power of the motor to the wheels; The driver operation system includes a cruise switch group, an accelerator pedal, a brake pedal, a shift switch, and a direction switch; The driver realizes the constant - speed cruise of the tractor by operating the driver operation system; The display system is connected to the engine management system EMS, the generator controller GCU, the motor controller MCU, and the battery management system BMC respectively through the CAN bus for data interaction, and is used to display the driving state information of the tractor; The vehicle controller is connected to the engine management system EMS, the generator controller GCU, the motor controller MCU, and the battery management system BMC through the CAN bus to obtain data information and send relevant control instructions; The vehicle controller is also connected to the driver operation system and the gearbox through hard - wires to obtain the driver's operation information, and execute the determination of the constant - speed cruise state, the setting of the constant - speed cruise speed, and the control of the power output of the constant - speed cruise; The direction switch includes a forward switch, a neutral switch, and a reverse switch, which is used to set the current running direction, stop, or perform a power reversal operation; The power reversal process of the tractor in the constant - speed cruise state is as follows: when the cruise speed is less than 20 km / h and the direction switch changes direction, the vehicle controller quickly reduces the vehicle speed to 0 km / h by requesting reverse torque from the motor. At the same time, the vehicle controller controls to stop the generator enabling. Then the vehicle controller requests a speed mode from the motor and outputs torque with a limited torque to increase the speed of the motor to the constant - speed cruise speed.

2. The constant speed cruise control system of a series hybrid tractor according to claim 1, characterized in that: The cruise switch group includes a cruise enable switch, a cruise speed increase switch, and a cruise speed decrease switch.

3. A cruise control method for a series hybrid tractor, characterized in that: Based on the constant - speed cruise control system described in claim 1 or 2, it specifically includes: The vehicle controller obtains the operation information of the tractor and judges whether it can enter the constant - speed cruise state; If the operation information meets the preset constant - speed cruise conditions, the cruise enable switch is activated to enter the constant - speed cruise state, and the current vehicle speed is used as the cruise speed; if not, the driving speed of the tractor is controlled by the accelerator pedal opening; When in the constant - speed cruise state, the vehicle controller receives the operation trigger signal from the driver operation system and adjusts the cruise speed, resets the cruise speed, and exits the constant - speed cruise state; When starting a power reversal in the constant - speed cruise state, the tractor still maintains the constant - speed cruise activation state, so that the tractor can continue to perform constant - speed cruise in the opposite direction after the power reversal, which is convenient for the tractor to turn around during operation.

4. A constant speed cruise control method for a series hybrid tractor according to claim 3, characterized in that: The constant speed cruise condition means that the energy system is operating normally, the transmission is not in neutral, the current driving speed is greater than the minimum threshold of the constant speed cruise speed, the brake switch is invalid, and the current driving direction is the forward direction.

5. The constant speed cruise control method of a series hybrid tractor according to claim 3, characterized in that: When the tractor is in the constant speed cruise state, the vehicle controller determines to exit the constant speed cruise state if any of the following conditions exist: the cruise enable switch is not activated, the brake switch is effective, the transmission gear is in neutral, the direction switch is in neutral, or there is a driveline fault. The vehicle controller records the gear and cruise speed used in this constant speed cruise operation for application during the constant speed cruise reset operation.

6. The constant speed cruise control method for a series hybrid tractor according to claim 3, characterized in that: When the tractor is in the constant speed cruise state, the driver presses the cruise speed increase switch and the cruise speed decrease switch simultaneously to perform the reset operation of the cruise speed. If the current gear is the same as the gear used in the previous constant speed cruise, the target cruise speed is set to the previous cruise speed; otherwise, the constant speed cruise state is exited.

7. A constant speed cruise control method for a series hybrid tractor according to claim 3, characterized in that: The exit of the constant speed cruise state includes two modes: complete exit and incomplete exit. The complete exit is achieved by turning off the cruise enable switch; the incomplete exit is achieved by any of the following methods: stepping on the brake pedal, changing the transmission gear, or the direction switch being in neutral. In the incomplete exit mode, the cruise enable switch remains activated to facilitate the reset operation of the cruise speed.

8. The constant speed cruise control method for a series hybrid tractor according to claim 3, characterized in that: When the tractor is in the constant speed cruise state, the adjustment method of the cruise speed is as follows: pressing the cruise speed increase switch or the cruise speed decrease switch controls the increase or decrease of the cruise speed respectively. The vehicle controller sets the maximum cruise speed and the minimum cruise speed for the current gear. If the target cruise speed to be adjusted is higher than the maximum cruise speed, the vehicle controller uses the maximum cruise speed for constant speed cruise; if the target cruise speed to be adjusted is lower than the minimum cruise speed, the vehicle controller uses the minimum cruise speed for constant speed cruise.

9. A constant speed cruise control method for a series hybrid tractor according to claim 8, characterized in that: When the tractor is in the constant speed cruise state, the vehicle controller sets the cruise speed increase and decrease units for the corresponding gear according to different operating gears.

10. A constant speed cruise control method for a series hybrid tractor according to claim 3, characterized in that: When the tractor is in the constant speed cruise state, when the accelerator pedal is depressed so that the requested driving speed is greater than the current cruise speed, the vehicle controller rapidly increases the driving speed according to the request signal of the accelerator pedal.

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