Gear calculation and shift control method and device for xev hybrid vehicle

Abstract

The application provides a gear calculation and shift control method and device for an XEV hybrid vehicle, and belongs to the technical field of vehicle shift control. The method comprises the following steps: a vehicle control unit (VCU) determines a vehicle operation mode according to a current vehicle speed and a throttle opening degree; the vehicle operation mode comprises a waiting start mode, a vehicle driving mode and an energy recovery mode; in each vehicle operation mode, the VCU controls target gear setting of an electric drive axle and a traditional gearbox, and controls the switching process of the electric drive axle gear and the traditional gearbox gear in different driving modes; the driving mode comprises a pure electric driving mode, an engine-only driving mode and a hybrid driving mode. The application realizes target gear calculation and shift process control of the XEV hybrid vehicle, guarantees the smoothness of XEV vehicle shift, realizes coordinated control of shift structure gear shifting, ensures uninterrupted power during gear shifting, and improves fuel economy.

Description

Technical Field

[0001] This invention belongs to the field of vehicle shift control technology, specifically relating to a method and device for gear calculation and shift control of an XEV hybrid vehicle. Background Technology

[0002] Commercial hybrid vehicles that use an engine and an electric motor as their power source are classified into various architectures, P0-P4, based on the combination of the electric motor in the vehicle's power output structure. In P0 and P1 architectures, the electric motor and engine are coupled, and the vehicle's transmission uses a traditional gearbox with a clutch to engage with the engine for power transmission. Gear shifting control is similar to that of traditional gasoline-powered commercial vehicles, requiring engine speed control during shifting, combined with clutch control to ensure gear changes. In P2 and P3 architectures, the electric motor is structurally coupled to the input or output shaft of the transmission. Gear shifting control is achieved through the electric motor, eliminating the need for engine speed regulation. Clutch control differs from P0 and P1, but in case of motor failure, the same method as traditional gear shifting is used. In the P4 architecture, the electric motor is positioned near the wheels, and the transmission is coupled to the motor on the drive axle. Gear shifting is entirely controlled by the electric motor, while the engine acts as a range extender providing electrical energy and cannot output power to the wheels. Alternatively, if the electric motor is directly deployed at the wheels, the vehicle does not require a transmission mechanism at all.

[0003] As a variant of the P4 architecture, the XEV vehicle's engine and motor can either drive and output power independently or simultaneously. The drive motor is positioned close to the wheel end, and it uses both a traditional gearbox and an electric drive gearbox to transmit torque to the wheel end.

[0004] The gear shifting of traditional vehicles only considers the unit settings of traditional transmission mechanisms and is not applicable to XEV vehicles. The gear shifting under the traditional hybrid architecture only considers the gear shifting of the electric drive structure. That is, due to the different drive structure, there is a lack of effective methods for calculating the target gear and controlling the shifting process, especially when multiple transmission mechanisms are working at the same time, for XEV vehicles.

[0005] This is a shortcoming of the existing technology. Therefore, it is very necessary to provide a method and device for gear calculation and shift control of XEV hybrid vehicles to address the above-mentioned defects in the existing technology. Summary of the Invention

[0006] In view of the shortcomings of existing technologies, such as the lack of an effective method for calculating the target gear and controlling the shifting process in XEV vehicles, especially when multiple transmission mechanisms are working simultaneously, due to different drive structure forms, this invention provides a method and device for calculating gears and controlling shifting in XEV hybrid vehicles to solve the above-mentioned technical problems.

[0007] In a first aspect, the present invention provides a method for gear calculation and shift control of an XEV hybrid vehicle, comprising the following steps: S1. The vehicle control unit (VCU) determines the vehicle operating mode based on the current vehicle speed and throttle opening; the vehicle operating mode includes waiting start mode, vehicle drive mode, and energy recovery mode. S2. In each vehicle operating mode, the vehicle control unit (VCU) controls the target gear setting of the electric drive axle and the conventional transmission, and controls the gear switching process of the electric drive axle and the conventional transmission in different driving modes; the driving modes include pure electric drive mode, engine-only drive mode and hybrid drive mode.

[0008] Furthermore, the specific steps of step S1 are as follows: S11. The vehicle control unit (VCU) determines whether the vehicle speed is 0. If so, proceed to step S12; If not, proceed to step S15; S12. The vehicle control unit (VCU) obtains the shift lever status fed back by the shift lever controller; When the handle is in neutral, proceed to step S13; When the handle is pushed from the neutral position to the gear position, proceed to step S14; S13. The vehicle control unit (VCU) determines that the XEV hybrid vehicle is in a waiting start mode, waits for a set time period, and then returns to step S12. S14. The vehicle control unit (VCU) determines that the XEV hybrid vehicle is in the starting phase, performs the transition from the waiting start mode to the vehicle drive mode, and proceeds to step S2. S15. The vehicle control unit (VCU) determines whether the throttle opening is 0. If so, proceed to step S16; If not, proceed to step S18; S16. The vehicle control unit (VCU) determines whether the vehicle speed is greater than the coasting speed threshold, or whether the brake pedal opening is not 0. If so, proceed to step S17; If not, wait for the set time period and return to step S11; S17. The vehicle control unit (VCU) determines that the XEV vehicle is in a coasting or braking state, which is the energy recovery mode, and proceeds to step S2. S18. The vehicle control unit (VCU) determines whether the vehicle speed is greater than the starting speed threshold. If so, proceed to step S19; If not, wait for the set time period and return to step S11; S19. The vehicle control unit (VCU) determines that the XEV vehicle has entered the vehicle drive mode and proceeds to step S2.

[0009] Furthermore, the specific steps of step S2 are as follows: S21. The vehicle control unit (VCU) determines the vehicle's operating mode; When the vehicle transitions from waiting start mode to vehicle drive mode, proceed to step S22; When the vehicle is in vehicle driving mode, proceed to step S23; When the vehicle is in energy recovery mode, proceed to step S24; S22. The vehicle control unit (VCU) adjusts the electric drive axle gear to the first target gear and notifies the transmission shift controller to adjust the current gear of the transmission to the second target gear. After the gear setting is completed, the drive mode is determined according to the throttle opening, and the gear switching process is controlled in different drive modes. Then, the process returns to step S1. S23. The vehicle control unit (VCU) determines the drive mode type of the XEV vehicle, sets the target gear and controls the gear shifting process according to the drive mode type, and returns to step S1; S24. The vehicle control unit (VCU) keeps the electric drive axle gear position unchanged, sets the gearbox gear to neutral, and sets the clutch and engine disengagement status to ensure energy recovery benefits during coasting or braking.

[0010] Furthermore, the specific steps of step S22 are as follows: S221. The vehicle control unit (VCU) controls the electric drive axle to shift into the first target gear. S222. The vehicle control unit (VCU) sends the second target gear and the waiting start mode status value to the transmission shift controller via CAN message; S223. The transmission shift controller controls the engine and clutch, and adjusts the current gear of the transmission according to the second target gear; S224. The transmission shift controller determines whether the actual gear position of the transmission matches the second target gear position; If so, proceed to step S225; If not, return to step S223; S225. The gearbox shift controller controls the clutch to completely disengage from the engine and maintains the disengaged state; S226. The vehicle control unit (VCU) determines the power output source based on the throttle opening and performs drive mode judgment; When the throttle opening is less than or equal to the first opening threshold, proceed to step S227; When the throttle opening is greater than the first opening threshold and less than the second opening threshold, proceed to step S228; When the throttle opening is greater than the third opening threshold, proceed to step S229; S227. The vehicle control unit (VCU) determines that the XEV vehicle is powered by the electric motor, controls the electric drive axle to maintain the first target gear, and sends the second target gear and pure electric drive mode status value to the transmission shift controller, controls the clutch to completely disengage from the engine, and returns to step S18 to determine the vehicle speed. S228. The vehicle control unit (VCU) determines that the XEV vehicle is powered by the engine, sends the second target gear value and the engine-only drive mode status value to the transmission shift controller, controls the clutch to engage with the engine, controls the electric drive axle to maintain the first target gear, sends a torque command to the engine controller (ECU) to control the engine output torque, and returns to step S18 to determine the vehicle speed. S229. The vehicle control unit (VCU) determines that the XEV vehicle's power is provided by both the engine and the electric motor. It sends the second target gear value and the hybrid drive mode status value to the transmission shift controller, controls the clutch to engage with the engine, controls the electric drive axle to maintain the first target gear, sends a torque command to the engine controller (ECU) to control the engine output torque, and simultaneously controls the electric motor to output torque. It then returns to step S18 to determine the vehicle speed.

[0011] Furthermore, the specific steps of step S23 are as follows: S231. The vehicle control unit (VCU) determines the drive mode type of the XEV vehicle; When the drive mode type is pure electric drive mode, proceed to step S232; When the drive mode type is engine-only drive mode, proceed to step S233; When the drive mode type is hybrid drive mode, proceed to step S234; S232. The vehicle controller (VCU) notifies the engine controller (ECU) to maintain the engine at idle speed, and notifies the transmission shift controller to maintain the transmission in neutral. Based on the vehicle speed and power requirements, the target gear of the electric drive axle is set by looking up a table, and the shifting process of the motor is controlled. Then, the process returns to step S1. S233. The vehicle control unit (VCU) sets the electric drive axle gear, sets the target gear of the transmission by looking up a table based on the vehicle speed and power requirements, and controls the transmission to switch gears based on the relationship between the current vehicle power requirements and the maximum power that the electric drive axle can output at the current vehicle speed. Then, return to step S1. S234. The vehicle control unit (VCU) sets the target gears for the transmission and electric drive axle based on the power already allocated to the engine and electric drive axle, using the target gear table for the hybrid mode transmission and the target gear table for the hybrid mode electric drive axle. It then distributes the power between the engine and electric drive axle according to the maximum allowable power of the electric drive axle and engine at the corresponding vehicle speed, thus completing the gear shifting process control.

[0012] Furthermore, the specific steps of step S232 are as follows: S2321. The vehicle control unit (VCU) sends a torque command to the engine control unit (ECU) to control the engine to maintain idling speed and keep the vehicle's air supply system running. S2322. The vehicle control unit (VCU) sends the target gear position (neutral) and pure electric drive mode status values ​​to the transmission shift controller, which controls the transmission to maintain neutral, sets the clutch to disengage from the engine, and maintains this position throughout the entire process. S2323. The vehicle controller (VCU) obtains the optimal motor efficiency gear setting table for different vehicle speeds and power corresponding to the XEV vehicle, obtains the vehicle speed and power requirements, and performs a lookup of the optimal motor efficiency gear setting table based on the vehicle speed and power requirements to obtain the target gear of the electric drive axle. S2324. The vehicle control unit (VCU) coordinates the motor to control the speed adjustment and gear shifting process according to the target gear position of the electric drive axle.

[0013] Furthermore, the specific steps of step S233 are as follows: S2331. In order to reduce the energy recovery loss when entering the energy recovery mode, the vehicle controller (VCU) sets the target gear of the electric drive axle according to the electric drive axle gear ratio, the maximum speed of the XEV vehicle and the motor speed limit. S2332. The vehicle controller (VCU) pre-calculates the fuel consumption of different gears corresponding to the same power at the same vehicle speed based on the engine power-fuel consumption curve and engine speed limit of the XEV vehicle. It then uses the gear with the optimal fuel consumption as the target gear mapping value corresponding to the current vehicle speed and power to generate a gear table corresponding to the vehicle speed and power. S2333. The vehicle control unit (VCU) obtains the current vehicle speed and power, looks up the gear position table to obtain the gear position lookup value, and then filters the gear position lookup value of the gear position table in combination with the throttle opening to obtain the gear position of the gear. The gear position of the gear is then sent to the gear position controller. S2334. During the process of the gearbox shift controller controlling the gearbox shifting, the vehicle control unit (VCU) obtains the current vehicle power demand P1 and the maximum power P2 that the electric drive axle can output at the current vehicle speed, and compares the relationship between the two. If P1≤P2, proceed to step S2335; If P1 > P2, proceed to step S2336; S2335. The vehicle controller (VCU) allocates the current vehicle power demand P1 to the electric drive axle, causing the electric drive axle to output power. After the gearbox shifts gears, the VCU sets the electric drive axle output power to 0 and the engine output power to P1, then returns to step S1. S2336. The vehicle control unit (VCU) sets the electric drive axle to output power at maximum power P2, and after the gearbox shifts gears, sets the electric drive axle output power to 0 and sets the engine output power to P1.

[0014] Furthermore, the specific steps of step S234 are as follows: S2341. Based on the set fuel and electric energy conversion ratio coefficient, combined with the engine fuel curve, motor efficiency, engine speed limit and motor speed limit, calculate the gear value corresponding to each speed point and power point in the set speed interval and power interval in the hybrid mode, and obtain the target gear table of the hybrid mode transmission and the target gear table of the hybrid mode electric drive axle. S2342. The vehicle control unit (VCU) looks up the target gear position table of the hybrid mode transmission based on the power P5 allocated to the engine and the current vehicle speed to obtain the target gear position value of the transmission, and sends the target gear position value of the transmission and the hybrid mode status value to the transmission gear position controller. S2343. The vehicle controller (VCU) looks up the target gear value of the electric drive axle based on the power P4 allocated to the electric drive axle and the current vehicle speed, and then sends the target gear value of the electric drive axle to the electric drive axle. S2344. The vehicle control unit (VCU) obtains the maximum allowable power P2 of the electric drive axle and the maximum allowable power P6 of the engine at the current vehicle speed, and determines the gear shifting requirement. When the transmission needs to shift gears, proceed to step S2345; When the electric drive axle needs to switch gears, proceed to step S2346; When both the transmission and the electric drive axle need to switch gears, proceed to step S2349. S2345. The vehicle control unit (VCU) controls the electric drive axle to maintain the gear position, adjusts the power allocated to the electric drive axle to the maximum allowable power P2 of the electric drive axle, waits for the gearbox to complete the gear shift, and then adjusts the power of the electric drive axle back to the original power P4 to complete the gearbox shift and return to step S1. S2346. The gear value sent by the vehicle controller (VCU) to the gearbox gear controller remains unchanged. Determine the relationship between the current XEV vehicle power demand P3 and the engine's maximum allowable power P6. When P3≤P6, proceed to step S2347; When P3 > P6, proceed to step S2348; S2347. The vehicle control unit (VCU) sets the engine output power to the current XEV vehicle's required power P3, waits for the electric drive axle gear shift to complete, then adjusts the engine output power back to the original power P5, completes the electric drive axle gear shift, and returns to step S1. S2348. The vehicle controller (VCU) sets the transmitter output power to the engine's maximum allowable power P6, waits for the electric drive axle gear shift to complete, then adjusts the engine output power back to the original power P5, completes the electric drive axle gear shift, and returns to step S1. S2349. First, perform gear shifting according to step S2345, then perform gear shifting for the electric drive axle according to steps S2346-S2348.

[0015] Furthermore, the specific steps of step S24 are as follows: S241. The vehicle control unit (VCU) keeps the gear position of the electric drive axle unchanged and does not perform gear switching; S242. The vehicle control unit (VCU) sends the neutral gear as the target gear to the transmission gear controller via a CAN message, setting the transmission gear to neutral. S243. The vehicle control unit (VCU) is set to fully disengage the clutch and engine to ensure optimal energy recovery benefits during coasting or braking.

[0016] Secondly, the present invention provides a gear calculation and shift control device for an XEV hybrid vehicle, comprising: The vehicle operating mode determination module is used to enable the vehicle controller (VCU) to determine the vehicle operating mode based on the current vehicle speed and throttle opening; the vehicle operating modes include waiting start mode, vehicle driving mode and energy recovery mode; The gear shifting control module is used to control the target gear setting of the electric drive axle and the conventional transmission in various vehicle operating modes, and to control the gear shifting process of the electric drive axle and the conventional transmission in different driving modes; the driving modes include pure electric drive mode, engine-only drive mode and hybrid drive mode.

[0017] The beneficial effects of this invention are as follows: The present invention provides a method and device for gear calculation and shift control of XEV hybrid vehicles, which realizes the calculation of target gear and control of shift process of XEV hybrid vehicles, ensures smooth shifting of XEV vehicles, realizes coordinated control of gear shifting of transmission structure, ensures uninterrupted power during shifting, and improves fuel economy.

[0018] Furthermore, the design principle of this invention is reliable, the structure is simple, and it has a very wide range of application prospects.

[0019] Therefore, it is evident that the present invention has outstanding substantive features and significant progress compared with the prior art, and the beneficial effects of its implementation are also obvious. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating an embodiment of the gear calculation and shift control method for XEV hybrid vehicles according to the present invention.

[0022] Figure 2 This is a flowchart illustrating another embodiment of the gear calculation and shift control method for XEV hybrid vehicles of the present invention.

[0023] Figure 3 This is a schematic diagram of the gear calculation and shift control device for the XEV hybrid vehicle of the present invention.

[0024] Figure 4 This is a schematic diagram of the drive structure of the XEV hybrid vehicle of the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0026] To address the issue of lacking an effective method for target gear calculation and shift process control in XEV vehicles, especially when multiple transmission mechanisms are operating simultaneously, due to differences in drive structure, this paper proposes a method based on... Figure 4 The XEV vehicle structure shown includes not only the 16-speed gearbox and clutch of a traditional commercial vehicle, but also a 2-speed single-motor drive axle output mechanism. This is addressed through the following embodiments to ensure smooth gear shifting and fuel economy during normal driving of the XEV vehicle.

[0027] Example 1: like Figure 1As shown, the present invention provides a method for gear calculation and shift control of an XEV hybrid vehicle, comprising the following steps: S1. The vehicle control unit (VCU) determines the vehicle operating mode based on the current vehicle speed and throttle opening; the vehicle operating mode includes waiting start mode, vehicle drive mode, and energy recovery mode. S2. In each vehicle operating mode, the vehicle control unit (VCU) controls the target gear setting of the electric drive axle and the conventional transmission, and controls the gear switching process of the electric drive axle and the conventional transmission in different driving modes; the driving modes include pure electric drive mode, engine-only drive mode and hybrid drive mode.

[0028] Example 2: like Figure 2 As shown, the present invention provides a method for gear calculation and shift control of an XEV hybrid vehicle, comprising the following steps: S1. The vehicle control unit (VCU) determines the vehicle operating mode based on the current vehicle speed and throttle opening; the vehicle operating mode includes a waiting start mode, a vehicle driving mode, and an energy recovery mode; the specific steps of step S1 are as follows: S11. The vehicle control unit (VCU) determines whether the vehicle speed is 0. If so, proceed to step S12; If not, proceed to step S15; S12. The vehicle control unit (VCU) obtains the shift lever status fed back by the shift lever controller; When the handle is in neutral, proceed to step S13; When the handle is pushed from the neutral position to the gear position, proceed to step S14; S13. The vehicle control unit (VCU) determines that the XEV hybrid vehicle is in a waiting start mode, waits for a set time period, and then returns to step S12. S14. The vehicle control unit (VCU) determines that the XEV hybrid vehicle is in the starting phase, performs the transition from the waiting start mode to the vehicle drive mode, and proceeds to step S2. S15. The vehicle control unit (VCU) determines whether the throttle opening is 0. If so, proceed to step S16; If not, proceed to step S18; S16. The vehicle control unit (VCU) determines whether the vehicle speed is greater than the coasting speed threshold, or whether the brake pedal opening is not 0. If so, proceed to step S17; If not, wait for the set time period and return to step S11; S17. The vehicle control unit (VCU) determines that the XEV vehicle is in a coasting or braking state, which is the energy recovery mode, and proceeds to step S2. S18. The vehicle control unit (VCU) determines whether the vehicle speed is greater than the starting speed threshold. If so, proceed to step S19; If not, wait for the set time period and return to step S11; S19. The vehicle control unit (VCU) determines that the XEV vehicle has entered the vehicle drive mode and proceeds to step S2. The actual gear position and gear shifting process of the traditional transmission are monitored and controlled by the transmission shift controller TCU_A. The actual gear position of the electric drive axle is monitored by the gear position monitoring controller TCU_B. The gear shifting process of the electric drive axle is controlled by the vehicle controller VCU. The target gear position setting of the electric drive axle and the traditional transmission is determined by the vehicle controller VCU. The coordination process of the gear shifting process of the electric drive axle and the traditional transmission is controlled by the vehicle controller VCU. The shift lever controller uses the lever position signal to feedback the driver's current demand for the vehicle's direction of travel. The engine control is controlled by the engine controller ECU. S2. In each vehicle operating mode, the vehicle control unit (VCU) controls the target gear setting of the electric drive axle and the conventional transmission, and controls the gear switching process of the electric drive axle and the conventional transmission in different driving modes; the driving modes include pure electric drive mode, engine-only drive mode, and hybrid drive mode; the specific steps of step S2 are as follows: S21. The vehicle control unit (VCU) determines the vehicle's operating mode; When the vehicle transitions from waiting start mode to vehicle drive mode, proceed to step S22; When the vehicle is in vehicle driving mode, proceed to step S23; When the vehicle is in energy recovery mode, proceed to step S24; Based on the vehicle's current speed and throttle position, the vehicle's operating mode can be divided into waiting to start, vehicle drive mode, and energy recovery mode. When the vehicle's throttle opening is greater than that in drive mode, the vehicle is divided into three different drive modes according to the different drive power requirements: pure electric drive mode, engine-only drive mode, and hybrid drive mode. S22. The vehicle control unit (VCU) adjusts the electric drive axle gear to the first target gear and notifies the transmission shift controller to adjust the current gear of the transmission to the second target gear. After the gear setting is completed, the drive mode is determined according to the throttle opening, and the gear switching process is controlled in different drive modes. Then, the process returns to step S1. Here, the first target gear can be set to first gear. The specific steps of step S22 are as follows: S221. The vehicle control unit (VCU) controls the electric drive axle to shift into the first target gear. S222. The vehicle control unit (VCU) sends the second target gear and the waiting start mode status value to the transmission shift controller via CAN message; S223. The transmission shift controller controls the engine and clutch, and adjusts the current gear of the transmission according to the second target gear; S224. The transmission shift controller determines whether the actual gear position of the transmission is consistent with the second target gear position; If so, proceed to step S225; If not, return to step S223; S225. The gearbox shift controller controls the clutch to completely disengage from the engine and maintains the disengaged state; S226. The vehicle control unit (VCU) determines the power output source based on the throttle opening and performs drive mode judgment; When the throttle opening is less than or equal to the first opening threshold, proceed to step S227; When the throttle opening is greater than the first opening threshold and less than the second opening threshold, proceed to step S228; When the throttle opening is greater than the third opening threshold, proceed to step S229; S227. The vehicle control unit (VCU) determines that the XEV vehicle is powered by the electric motor, controls the electric drive axle to maintain the first target gear, and sends the second target gear and pure electric drive mode status value to the transmission shift controller, controls the clutch to completely disengage from the engine, and returns to step S18 to determine the vehicle speed. S228. The vehicle control unit (VCU) determines that the XEV vehicle is powered by the engine, sends the second target gear value and the engine-only drive mode status value to the transmission shift controller, controls the clutch to engage with the engine, controls the electric drive axle to maintain the first target gear, sends a torque command to the engine controller (ECU) to control the engine output torque, and returns to step S18 to determine the vehicle speed. S229. The vehicle control unit (VCU) determines that the XEV vehicle's power is provided by both the engine and the motor. It sends the second target gear value and the hybrid drive mode status value to the transmission shift controller, controls the clutch to engage with the engine, controls the electric drive axle to maintain the first target gear, sends a torque command to the engine controller (ECU) to control the engine output torque, and simultaneously controls the motor to output torque. It then returns to step S18 to determine the vehicle speed. When the vehicle engine is ignited and starting is required, the Vehicle Control Unit (VCU) confirms the shift lever position has been shifted from neutral to gear based on feedback from the shift controller. The VCU then controls the electric drive axle to shift into first gear and simultaneously sends the target gear value Tar_1 and a waiting-to-start mode status value to the Transmission Shift Control Unit (TCU_A) via CAN message. Upon receiving these values, the TCU_A controls the engine and clutch, adjusting the transmission's current gear to the target gear Tar_1. Once the actual gear matches the target gear, the TCU_A keeps the clutch fully disengaged from the engine. The first throttle opening threshold is App_Ev_C, and the second threshold is App_OD_C. The power output during driver start-up is related to the throttle opening; when the throttle opening App_r ≤ App_Ev_C, the vehicle... The output power is provided by the electric motor. The target gear of the electric drive axle controlled by the vehicle controller (VCU) remains unchanged, still in first gear. The target gear value sent to TCU_A remains unchanged, and the mode status value switches to pure electric drive mode. TCU_A keeps the clutch and engine completely disengaged. Once the vehicle speed V_Veh is greater than the starting speed threshold V_Veh_Strt, the vehicle enters vehicle drive mode. When the accelerator pedal opening App_EV_C < App_r < App_OD_C during start-up, the vehicle output power is provided by the engine, and the VCU sends the target gear value. The gear Tar_1 value and the engine-only drive mode status value are sent to the transmission shift controller TCU_A. TCU_A controls the clutch and engine to engage. The target gear of the electric drive axle controlled by VCU remains unchanged, still in first gear. VCU sends a torque command to ECU to control the engine output torque. When the vehicle speed V_Veh is greater than the starting speed threshold V_Veh_Strt, the vehicle enters the vehicle drive mode. When the accelerator pedal opening App_r is greater than App_OD_C during start-up, the vehicle output power is simultaneously output by the engine and motor. The vehicle controller VCU sends the target gear Tar_1 value and the engine-only drive mode status value to the transmission shift controller TCU_A. The transmission shift controller TCU_A controls the clutch and engine to engage. The target gear of the electric drive axle controlled by VCU remains unchanged, still in first gear. The transmission shift controller VCU sends a torque command to ECU to control the engine output torque, and simultaneously controls the motor to output torque. When the vehicle speed V_Veh is greater than the starting speed threshold V_Veh_Strt, the vehicle enters the vehicle drive mode. S23. The vehicle control unit (VCU) determines the drive mode type of the XEV vehicle, sets the target gear and controls the gear shifting process according to the drive mode type, and returns to step S1; the specific steps of step S23 are as follows: S231. The vehicle control unit (VCU) determines the drive mode type of the XEV vehicle; When the drive mode type is pure electric drive mode, proceed to step S232; When the drive mode type is engine-only drive mode, proceed to step S233; When the drive mode type is hybrid drive mode, proceed to step S234; S232. The vehicle control unit (VCU) notifies the engine control unit (ECU) to maintain the engine at idle speed, and notifies the transmission shift controller to maintain the transmission in neutral. Based on vehicle speed and power requirements, it looks up a table to set the target gear for the electric drive axle and controls the motor's shifting process, then returns to step S1. The specific steps of step S232 are as follows: S2321. The vehicle control unit (VCU) sends a torque command to the engine control unit (ECU) to control the engine to maintain idling speed and keep the vehicle's air supply system running. S2322. The vehicle control unit (VCU) sends the target gear position (neutral) and pure electric drive mode status values ​​to the transmission shift controller, which controls the transmission to maintain neutral, sets the clutch to disengage from the engine, and maintains this position throughout the entire process. S2323. The vehicle controller (VCU) obtains the optimal motor efficiency gear setting table for different vehicle speeds and power corresponding to the XEV vehicle, obtains the vehicle speed and power requirements, and performs a lookup of the optimal motor efficiency gear setting table based on the vehicle speed and power requirements to obtain the target gear of the electric drive axle. S2324. The vehicle control unit (VCU) coordinates the motor to control the speed adjustment and gear shifting process according to the target gear position of the electric drive axle; After the vehicle enters drive mode, when the vehicle is in pure electric drive mode, the vehicle control unit (VCU) sends torque commands to the ECU to control the engine to maintain idle speed, which is used to keep the vehicle's air supply system running. The VCU sends the target gear (neutral) and pure electric drive mode status values ​​to the transmission shift controller (TCU_A). The TCU_A controls the transmission to maintain neutral and sets the clutch to be fully disengaged from the engine. The vehicle's power output is provided by the electric motor. The target gear setting of the electric drive axle is calculated in advance based on the vehicle speed and power requirements, and the optimal efficiency range of the motor. The optimal gear setting table Map_Motor is calculated in advance for different vehicle speeds and power levels. When the vehicle is running in pure electric drive mode, the target gear of the electric drive axle is set by checking Map_Motor through the vehicle control unit (VCU). The gear switching process is controlled by the vehicle control unit (VCU) in coordination with the motor to adjust the speed and shift gears. S233. The vehicle control unit (VCU) sets the electric drive axle gear, looks up the target gear of the transmission according to the vehicle speed and power requirements, and controls the transmission to switch gears based on the relationship between the current vehicle power requirement and the maximum power that the electric drive axle can output at the current vehicle speed. The process then returns to step S1. The specific steps of step S233 are as follows: S2331. In order to reduce the energy recovery loss when entering the energy recovery mode, the vehicle controller (VCU) sets the target gear of the electric drive axle according to the electric drive axle gear ratio, the maximum speed of the XEV vehicle and the motor speed limit. S2332. The vehicle controller (VCU) pre-calculates the fuel consumption of different gears corresponding to the same power at the same vehicle speed based on the engine power-fuel consumption curve and engine speed limit of the XEV vehicle. It then uses the gear with the optimal fuel consumption as the target gear mapping value corresponding to the current vehicle speed and power to generate a gear table corresponding to the vehicle speed and power. S2333. The vehicle control unit (VCU) obtains the current vehicle speed and power, looks up the gear position table to obtain the gear position lookup value, and then filters the gear position lookup value of the gear position table in combination with the throttle opening to obtain the gear position of the gear. The gear position of the gear is then sent to the gear position controller. S2334. During the process of the gearbox shift controller controlling the gearbox shifting, the vehicle control unit (VCU) obtains the current vehicle power demand P1 and the maximum power P2 that the electric drive axle can output at the current vehicle speed, and compares the relationship between the two. If P1≤P2, proceed to step S2335; If P1 > P2, proceed to step S2336; S2335. The vehicle controller (VCU) allocates the current vehicle power demand P1 to the electric drive axle, causing the electric drive axle to output power. After the gearbox shifts gears, the VCU sets the electric drive axle output power to 0 and the engine output power to P1, then returns to step S1. S2336. The vehicle control unit (VCU) sets the electric drive axle to output power at the maximum power P2, and after the gearbox shifts gears, sets the electric drive axle output power to 0 and sets the engine output power to P1. When the vehicle is in engine-only drive mode, the vehicle's power output comes entirely from the engine, and the electric motor does not need to output power. To minimize energy recovery losses when the vehicle transitions from engine-only drive mode to energy recovery mode and to ensure the electric motor quickly enters braking torque output mode, the electric drive axle needs to be kept in gear during engine-only drive mode to prevent it from shifting gears during braking. This ensures energy recovery benefits. Considering the electric drive axle gear ratio, the maximum vehicle speed coverage, and the motor speed limit, the vehicle control unit (VCU) sets the electric drive axle gear to second gear in engine-only drive mode. Based on the engine power-fuel consumption curve and engine speed limit, the following calculations are performed for the same power output at the same vehicle speed: The optimal fuel consumption for each gear is selected as the target gear map fill value corresponding to the current vehicle speed and power, ultimately forming a gear table Map_EngShiftOd with the horizontal axis representing the vehicle speed range from 0-100km / h and the vertical axis representing the power range from 0 to the engine direct drive mode power limit value Pwr_EngOd. The vehicle controller VCU looks up the target gear Tar_set in the Map_EngShiftOd table based on the current vehicle speed and power, and then performs a filtering process on the target gear value Tar_set in combination with the throttle opening to obtain the final target gear value Tar_set_od. The target gear value Tar_set_od is then sent to the controller TCU_A via the CAN bus. When the vehicle is in engine-only drive mode, during the TCU_A control of the transmission to switch gears, if the current power demand of the vehicle is P1 and the maximum power that the electric drive axle can output at the current vehicle speed is P2, when P1≤P2, the current power demand of the vehicle P1 is allocated to the electric drive axle, allowing the electric drive axle to output power. After the transmission gear shift is completed, the output power of the electric drive axle is set to 0, and the engine output power is set to P1. When P1>P2, the electric drive axle is set to output at the maximum power P2. After the transmission gear shift is completed, the output power of the electric drive axle is set to 0, and the engine output power is set to P1. S234. The vehicle control unit (VCU) sets the target gears for the transmission and electric drive axle based on the power already allocated to the engine and electric drive axle, using the target gear table for the hybrid mode transmission and the target gear table for the hybrid mode electric drive axle. It then allocates power between the engine and electric drive axle according to the maximum permissible power at the corresponding vehicle speed, completing the gear shifting process control. The specific steps of S234 are as follows: S2341. Based on the set fuel and electric energy conversion ratio coefficient, combined with the engine fuel curve, motor efficiency, engine speed limit and motor speed limit, calculate the gear value corresponding to each speed point and power point in the set speed interval and power interval in the hybrid mode, and obtain the target gear table of the hybrid mode transmission and the target gear table of the hybrid mode electric drive axle. S2342. The vehicle control unit (VCU) looks up the target gear position table of the hybrid mode transmission based on the power P5 allocated to the engine and the current vehicle speed to obtain the target gear position value of the transmission, and sends the target gear position value of the transmission and the hybrid mode status value to the transmission gear position controller. S2343. The vehicle controller (VCU) looks up the target gear value of the electric drive axle based on the power P4 allocated to the electric drive axle and the current vehicle speed, and then sends the target gear value of the electric drive axle to the electric drive axle. S2344. The vehicle control unit (VCU) obtains the maximum allowable power P2 of the electric drive axle and the maximum allowable power P6 of the engine at the current vehicle speed, and determines the gear shifting requirement. When the transmission needs to shift gears, proceed to step S2345; When the electric drive axle needs to switch gears, proceed to step S2346; When both the transmission and the electric drive axle need to switch gears, proceed to step S2349. S2345. The vehicle control unit (VCU) controls the electric drive axle to maintain the gear position, adjusts the power allocated to the electric drive axle to the maximum allowable power P2 of the electric drive axle, waits for the gearbox to complete the gear shift, and then adjusts the power of the electric drive axle back to the original power P4 to complete the gearbox shift and return to step S1. S2346. The gear value sent by the vehicle controller (VCU) to the gearbox gear controller remains unchanged. Determine the relationship between the current XEV vehicle power demand P3 and the engine's maximum allowable power P6. When P3≤P6, proceed to step S2347; When P3 > P6, proceed to step S2348; S2347. The vehicle control unit (VCU) sets the engine output power to the current XEV vehicle's required power P3, waits for the electric drive axle gear shift to complete, then adjusts the engine output power back to the original power P5, completes the electric drive axle gear shift, and returns to step S1. S2348. The vehicle controller (VCU) sets the transmitter output power to the engine's maximum allowable power P6, waits for the electric drive axle gear shift to complete, then adjusts the engine output power back to the original power P5, completes the electric drive axle gear shift, and returns to step S1. S2349. First, perform gear shifting according to step S2345, then perform gear shifting for the electric drive axle according to steps S2346-S2348. When the vehicle is in hybrid drive mode, both the engine and the electric motor participate in power output. Based on a set fuel-to-electricity conversion ratio coefficient of K1, calculations are performed in hybrid drive mode, with vehicle speed from 1 to 100 km / h and power output ranging from the lower limit P_Hev_Min to the upper limit P_max, with power output at 1 kW intervals per 1 km / h. At each power and speed point, based on the engine fuel curve, electric motor efficiency map, engine speed limit, and electric motor speed limit, the optimal transmission gear and the optimal electric drive axle gear are calculated for each power and speed. Finally, two... The hybrid mode transmission target gear setting table Map_EngHyd and the hybrid mode electric drive axle target gear setting table Map_MotorHyd are defined with vehicle speed on the horizontal axis and power on the vertical axis. During the VCU's control of the transmission and electric drive axle target gear setting, the transmission target gear setting value Tar_EngHyd is obtained by looking up the tables based on the current power P5 allocated to the engine by the VCU and the vehicle speed V_Veh. The electric drive axle target gear setting value Tar_MotHyd is obtained by looking up the tables based on the current power P4 allocated to the electric drive axle by the VCU and the vehicle speed V_Veh. The VCU then sets the transmission target gear setting value Tar_EngHyd to... The gHyd and hybrid drive mode status values ​​are sent to the TCU_A, which adjusts the transmission gear shifting. The electric drive axle gear shifting is controlled by the vehicle control unit (VCU). Let the maximum allowable power of the electric drive axle at the current vehicle speed be P2, and the maximum power of the engine at the current vehicle speed be P6. When the transmission needs to shift gears, the VCU controls the electric drive axle to maintain the gear and adjusts the power allocated to the electric drive axle to P2. After the TCU_A completes the gear shift, the VCU adjusts the power allocated to the electric drive axle to P4. When the electric drive axle shifts gears, the VCU sends the transmission gear values ​​to the TCU_A. The values ​​remain unchanged. If P3 ≤ P6, the VCU sets the current engine output power to P3. After the electric drive axle gear shift is complete, the VCU adjusts the engine output power to P5. If P3 > P6, the VCU sets the current engine output power to P6. After the electric drive axle gear shift is complete, the VCU adjusts the engine output power to P5. When both the electric drive axle target gear and the transmission target gear need to be shifted, the transmission gear shift is performed first. After the transmission gear shift is complete, the electric drive axle gear is shifted. This ensures that the vehicle power is not completely lost during gear shifting in hybrid drive mode, improving the success rate and smoothness of gear shifting. S24. The vehicle control unit (VCU) keeps the electric drive axle gear position unchanged, sets the transmission gear to neutral, and sets the clutch and engine to disengage to ensure energy recovery benefits during coasting or braking. The specific steps of S24 are as follows: S241. The vehicle control unit (VCU) keeps the gear position of the electric drive axle unchanged and does not perform gear switching; S242. The vehicle control unit (VCU) sends the neutral gear as the target gear to the transmission gear controller via a CAN message, setting the transmission gear to neutral. S243. The vehicle control unit (VCU) is set to fully disengage the clutch and engine to ensure optimal energy recovery during coasting or braking. When the vehicle throttle opening is 0 and the vehicle speed is greater than the coasting threshold V_Veh_Sp, or when the brake pedal opening is not 0, the vehicle is in a coasting or braking state. At this time, the vehicle operation mode will enter the energy recovery mode. When the vehicle is in the coasting or braking energy recovery state, the electric drive axle gear remains unchanged and no gear shifting is performed. If the vehicle mode enters the energy recovery mode, the vehicle controller VCU sends a target gear as neutral to the TCU_A via CAN message. The TCU_A sets the traditional transmission gear to neutral and simultaneously sets the clutch and engine to be completely disengaged to ensure the best energy recovery benefits during coasting and braking.

[0029] Example 3: like Figure 3 As shown, the present invention provides a gear calculation and shift control device for an XEV hybrid vehicle, comprising: The vehicle operating mode determination module is used to enable the vehicle controller (VCU) to determine the vehicle operating mode based on the current vehicle speed and throttle opening; the vehicle operating modes include waiting start mode, vehicle driving mode and energy recovery mode; The gear shifting control module is used to control the target gear setting of the electric drive axle and the conventional transmission in various vehicle operating modes, and to control the gear shifting process of the electric drive axle and the conventional transmission in different driving modes; the driving modes include pure electric drive mode, engine-only drive mode and hybrid drive mode.

[0030] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the invention should also be covered within the protection scope of the invention. Therefore, the protection scope of the invention should be determined by the scope of the claims.

Claims

1. A method for gear calculation and shift control in an XEV hybrid vehicle, characterized in that, Includes the following steps: S1. The vehicle control unit (VCU) determines the vehicle operating mode based on the current vehicle speed and throttle opening; the vehicle operating mode includes a waiting start mode, a vehicle driving mode, and an energy recovery mode; the specific steps of step S1 are as follows: S11. The vehicle control unit (VCU) determines whether the vehicle speed is 0. If so, proceed to step S12; If not, proceed to step S15; S12. The vehicle control unit (VCU) obtains the shift lever status fed back by the shift lever controller; When the handle is in neutral, proceed to step S13; When the handle is pushed from the neutral position to the gear position, proceed to step S14; S13. The vehicle control unit (VCU) determines that the XEV hybrid vehicle is in a waiting start mode, waits for a set time period, and then returns to step S12. S14. The vehicle control unit (VCU) determines that the XEV hybrid vehicle is in the starting phase, performs the transition from the waiting start mode to the vehicle drive mode, and proceeds to step S2. S15. The vehicle control unit (VCU) determines whether the throttle opening is 0. If so, proceed to step S16; If not, proceed to step S18; S16. The vehicle control unit (VCU) determines whether the vehicle speed is greater than the coasting speed threshold, or whether the brake pedal opening is not 0. If so, proceed to step S17; If not, wait for the set time period and return to step S11; S17. The vehicle control unit (VCU) determines that the XEV vehicle is in a coasting or braking state, which is the energy recovery mode, and proceeds to step S2. S18. The vehicle control unit (VCU) determines whether the vehicle speed is greater than the starting speed threshold. If so, proceed to step S19; If not, wait for the set time period and return to step S11; S19. The vehicle control unit (VCU) determines that the XEV vehicle has entered the vehicle drive mode and proceeds to step S2. S2. In each vehicle operating mode, the vehicle control unit (VCU) controls the target gear setting of the electric drive axle and the conventional transmission, and controls the gear switching process of the electric drive axle and the conventional transmission in different driving modes; the driving modes include pure electric drive mode, engine-only drive mode and hybrid drive mode. The specific steps of step S2 are as follows: S21. The vehicle control unit (VCU) determines the vehicle's operating mode; When the vehicle transitions from waiting start mode to vehicle drive mode, proceed to step S22; When the vehicle is in vehicle driving mode, proceed to step S23; When the vehicle is in energy recovery mode, proceed to step S24; S22. The vehicle control unit (VCU) adjusts the electric drive axle gear to the first target gear and notifies the transmission shift controller to adjust the current gear of the transmission to the second target gear. After the gear setting is completed, the drive mode is determined according to the throttle opening, and the gear switching process is controlled in different drive modes. Then, the process returns to step S1. S23. The vehicle control unit (VCU) determines the drive mode type of the XEV vehicle, sets the target gear and controls the gear shifting process according to the drive mode type, and returns to step S1; S24. The vehicle control unit (VCU) keeps the electric drive axle gear position unchanged, sets the gearbox gear to neutral, and sets the clutch and engine disengagement status to ensure energy recovery benefits during coasting or braking.

2. The gear calculation and shift control method for XEV hybrid vehicles as described in claim 1, characterized in that, The specific steps of step S22 are as follows: S221. The vehicle control unit (VCU) controls the electric drive axle to shift into the first target gear. S222. The vehicle control unit (VCU) sends the second target gear and the waiting start mode status value to the transmission shift controller via CAN message; S223. The transmission shift controller controls the engine and clutch, and adjusts the current gear of the transmission according to the second target gear; S224. The transmission shift controller determines whether the actual gear position of the transmission matches the second target gear position; If so, proceed to step S225; If not, return to step S223; S225. The gearbox shift controller controls the clutch to completely disengage from the engine and maintains the disengaged state; S226. The vehicle control unit (VCU) determines the power output source based on the throttle opening and performs drive mode judgment; When the throttle opening is less than or equal to the first opening threshold, proceed to step S227; When the throttle opening is greater than the first opening threshold and less than the second opening threshold, proceed to step S228; When the throttle opening is greater than the third opening threshold, proceed to step S229; S227. The vehicle control unit (VCU) determines that the XEV vehicle is powered by the electric motor, controls the electric drive axle to maintain the first target gear, and sends the second target gear and pure electric drive mode status value to the transmission shift controller, controls the clutch to completely disengage from the engine, and returns to step S18 to determine the vehicle speed. S228. The vehicle control unit (VCU) determines that the XEV vehicle is powered by the engine, sends the second target gear value and the engine-only drive mode status value to the transmission shift controller, controls the clutch to engage with the engine, controls the electric drive axle to maintain the first target gear, sends a torque command to the engine controller (ECU) to control the engine output torque, and returns to step S18 to determine the vehicle speed. S229. The vehicle control unit (VCU) determines that the XEV vehicle's power is provided by both the engine and the electric motor. It sends the second target gear value and the hybrid drive mode status value to the transmission shift controller, controls the clutch to engage with the engine, controls the electric drive axle to maintain the first target gear, sends a torque command to the engine controller (ECU) to control the engine output torque, and simultaneously controls the electric motor to output torque. It then returns to step S18 to determine the vehicle speed.

3. The gear calculation and shift control method for XEV hybrid vehicles as described in claim 1, characterized in that, The specific steps of step S23 are as follows: S231. The vehicle control unit (VCU) determines the drive mode type of the XEV vehicle; When the drive mode type is pure electric drive mode, proceed to step S232; When the drive mode type is engine-only drive mode, proceed to step S233; When the drive mode type is hybrid drive mode, proceed to step S234; S232. The vehicle controller (VCU) notifies the engine controller (ECU) to maintain the engine at idle speed, and notifies the transmission shift controller to maintain the transmission in neutral. Based on the vehicle speed and power requirements, the target gear of the electric drive axle is set by looking up a table, and the shifting process of the motor is controlled. Then, the process returns to step S1. S233. The vehicle control unit (VCU) sets the electric drive axle gear, sets the target gear of the transmission by looking up a table based on the vehicle speed and power requirements, and controls the transmission to switch gears based on the relationship between the current vehicle power requirements and the maximum power that the electric drive axle can output at the current vehicle speed. Then, return to step S1. S234. The vehicle control unit (VCU) sets the target gears for the transmission and electric drive axle based on the power already allocated to the engine and electric drive axle, using the target gear table for the hybrid mode transmission and the target gear table for the hybrid mode electric drive axle. It then distributes the power between the engine and electric drive axle according to the maximum allowable power of the electric drive axle and engine at the corresponding vehicle speed, thus completing the gear shifting process control.

4. The gear calculation and shift control method for XEV hybrid vehicles as described in claim 3, characterized in that, The specific steps of step S232 are as follows: S2321. The vehicle control unit (VCU) sends a torque command to the engine control unit (ECU) to control the engine to maintain idling speed and keep the vehicle's air supply system running. S2322. The vehicle control unit (VCU) sends the target gear position (neutral) and pure electric drive mode status values ​​to the transmission shift controller, which controls the transmission to maintain neutral, sets the clutch to disengage from the engine, and maintains this position throughout the entire process. S2323. The vehicle controller (VCU) obtains the optimal motor efficiency gear setting table for different vehicle speeds and power corresponding to the XEV vehicle, obtains the vehicle speed and power requirements, and performs a lookup of the optimal motor efficiency gear setting table based on the vehicle speed and power requirements to obtain the target gear of the electric drive axle. S2324. The vehicle control unit (VCU) coordinates the motor to control the speed adjustment and gear shifting process according to the target gear position of the electric drive axle.

5. The gear calculation and shift control method for XEV hybrid vehicles as described in claim 3, characterized in that, The specific steps of step S233 are as follows: S2331. In order to reduce the energy recovery loss when entering the energy recovery mode, the vehicle controller (VCU) sets the target gear of the electric drive axle according to the electric drive axle gear ratio, the maximum speed of the XEV vehicle and the motor speed limit. S2332. The vehicle controller (VCU) pre-calculates the fuel consumption of different gears corresponding to the same power at the same vehicle speed based on the engine power-fuel consumption curve and engine speed limit of the XEV vehicle. It then uses the gear with the optimal fuel consumption as the target gear mapping value corresponding to the current vehicle speed and power to generate a gear table corresponding to the vehicle speed and power. S2333. The vehicle control unit (VCU) obtains the current vehicle speed and power, looks up the gear position table to obtain the gear position lookup value, and then filters the gear position lookup value of the gear position table in combination with the throttle opening to obtain the gear position of the gear. The gear position of the gear is then sent to the gear position controller. S2334. During the process of the gearbox shift controller controlling the gearbox shifting, the vehicle control unit (VCU) obtains the current vehicle power demand P1 and the maximum power P2 that the electric drive axle can output at the current vehicle speed, and compares the relationship between the two. If P1≤P2, proceed to step S2335; If P1 > P2, proceed to step S2336; S2335. The vehicle controller (VCU) allocates the current vehicle power demand P1 to the electric drive axle, causing the electric drive axle to output power. After the gearbox shifts gears, the VCU sets the electric drive axle output power to 0 and the engine output power to P1, then returns to step S1. S2336. The vehicle control unit (VCU) sets the electric drive axle to output power at maximum power P2, and after the gearbox shifts gears, sets the electric drive axle output power to 0 and sets the engine output power to P1.

6. The gear calculation and shift control method for XEV hybrid vehicles as described in claim 3, characterized in that, The specific steps of step S234 are as follows: S2341. Based on the set fuel and electric energy conversion ratio coefficient, combined with the engine fuel curve, motor efficiency, engine speed limit and motor speed limit, calculate the gear value corresponding to each speed point and power point in the set speed interval and power interval in the hybrid mode, and obtain the target gear table of the hybrid mode transmission and the target gear table of the hybrid mode electric drive axle. S2342. The vehicle control unit (VCU) looks up the target gear position table of the hybrid mode transmission based on the power P5 allocated to the engine and the current vehicle speed to obtain the target gear position value of the transmission, and sends the target gear position value of the transmission and the hybrid mode status value to the transmission gear position controller. S2343. The vehicle controller (VCU) looks up the target gear value of the electric drive axle based on the power P4 allocated to the electric drive axle and the current vehicle speed, and then sends the target gear value of the electric drive axle to the electric drive axle. S2344. The vehicle control unit (VCU) obtains the maximum allowable power P2 of the electric drive axle and the maximum allowable power P6 of the engine at the current vehicle speed, and determines the gear shifting requirement. When the transmission needs to shift gears, proceed to step S2345; When the electric drive axle needs to switch gears, proceed to step S2346; When both the transmission and the electric drive axle need to switch gears, proceed to step S2349. S2345. The vehicle control unit (VCU) controls the electric drive axle to maintain the gear position, adjusts the power allocated to the electric drive axle to the maximum allowable power P2 of the electric drive axle, waits for the gearbox to complete the gear shift, and then adjusts the power of the electric drive axle back to the original power P4 to complete the gearbox shift and return to step S1. S2346. The gear value sent by the vehicle controller (VCU) to the gearbox gear controller remains unchanged. Determine the relationship between the current XEV vehicle power demand P3 and the engine's maximum allowable power P6. When P3≤P6, proceed to step S2347; When P3 > P6, proceed to step S2348; S2347. The vehicle control unit (VCU) sets the engine output power to the current XEV vehicle's required power P3, waits for the electric drive axle gear shift to complete, then adjusts the engine output power back to the original power P5, completes the electric drive axle gear shift, and returns to step S1. S2348. The vehicle controller (VCU) sets the transmitter output power to the engine's maximum allowable power P6, waits for the electric drive axle gear shift to complete, then adjusts the engine output power back to the original power P5, completes the electric drive axle gear shift, and returns to step S1. S2349. First, perform gear shifting according to step S2345, then perform gear shifting for the electric drive axle according to steps S2346-S2348.

7. The method for gear calculation and shift control of an XEV hybrid vehicle as described in claim 1, characterized in that, The specific steps of step S24 are as follows: S241. The vehicle control unit (VCU) keeps the gear position of the electric drive axle unchanged and does not perform gear switching; S242. The vehicle control unit (VCU) sends the neutral gear as the target gear to the transmission gear controller via a CAN message, setting the transmission gear to neutral. S243. The vehicle control unit (VCU) is set to fully disengage the clutch and engine to ensure optimal energy recovery benefits during coasting or braking.

8. A gear calculation and shift control device for an XEV hybrid vehicle, using the method described in any one of claims 1-7, characterized in that, include: The vehicle operating mode determination module is used to enable the vehicle controller (VCU) to determine the vehicle operating mode based on the current vehicle speed and throttle opening. The vehicle operation modes include waiting to start mode, vehicle driving mode, and energy recovery mode; The gear shifting control module is used to control the target gear setting of the electric drive axle and the conventional transmission in various vehicle operating modes, and to control the gear shifting process of the electric drive axle and the conventional transmission in different driving modes; the driving modes include pure electric drive mode, engine-only drive mode and hybrid drive mode.

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