Hybrid drive system based on three-gear transmission, control method and vehicle

Abstract

This invention discloses a hybrid drive system based on a three-speed transmission, including a front axle power assembly, a three-speed hybrid transmission, a rear axle drive assembly, and an energy management system. The front axle power assembly includes a connected engine and a P1 motor. The input end of the three-speed hybrid transmission is connected to the P1 motor via a clutch, and the output end of the three-speed hybrid transmission is connected to the front wheels of the vehicle. The rear axle drive assembly is connected to the rear wheels of the vehicle and includes a P4 motor. This invention's three-speed hybrid drive system, with its dual-motor configuration, enables pure electric rear-wheel drive, series rear-wheel drive, parallel front-wheel drive, and four-wheel drive modes. It can enter parallel operation at 0 speed, and a traction mode is set to ensure that the engine and motor enter parallel operation at low speeds to increase wheel-side torque. By integrating the three-speed transmission with the P1 motor and setting the P4 motor to drive the rear wheels, fuel efficiency is improved while reducing the hybrid gearbox size, simplifying layout, and enhancing feasibility. This invention also discloses a vehicle and a control method for the three-speed hybrid drive system.

Description

Technical Field

[0001] This invention belongs to the field of hybrid vehicle technology. Specifically, this invention relates to a hybrid drive system, control method, and vehicle based on a three-speed transmission. Background Technology

[0002] With the continuous development of the automotive industry, hybrid technology has become an important development direction for current automotive power systems due to its good balance between fuel economy and power performance. Among them, the P1P3 hybrid architecture, as a common form of hybrid, has played a certain role in vehicle power output and energy utilization. However, in practical applications, this architecture has gradually exposed many problems, limiting its further promotion and application.

[0003] Specifically, the existing P1P3 hybrid architecture has a relatively limited drive mode, supporting only front-wheel drive and unable to achieve rear-wheel drive or four-wheel drive. This significantly restricts power output when the vehicle encounters complex road conditions, such as climbing hills or driving on slippery surfaces, making it difficult to meet diverse driving needs.

[0004] At the same time, this architecture has limitations in terms of parallel mode intervention. The engine can only enter parallel mode after the vehicle reaches a certain speed. At 0 speed, torque superposition cannot be achieved, resulting in insufficient vehicle traction. When the vehicle is stuck in mud, potholes, or other difficult situations, it is difficult to get out on its own.

[0005] Furthermore, in the existing P1P3 hybrid architecture, the P3 motor is integrated with the multi-speed transmission, which directly results in an excessively large hybrid gearbox. This not only encroaches on the space of the vehicle's engine compartment, making engine compartment layout more difficult, but also increases the difficulty of achieving vehicle lightweighting, which is not conducive to further improving the vehicle's fuel economy and handling performance.

[0006] This invention provides a hybrid drive system based on a three-speed transmission, with a particular focus on how to effectively reduce the size of the hybrid gearbox and improve its layout feasibility. Summary of the Invention

[0007] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a hybrid power drive system based on a three-speed transmission, with the purpose of effectively reducing the size of the hybrid gearbox and improving its layout feasibility.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a hybrid drive system based on a three-speed transmission, including a front axle power assembly, a three-speed hybrid transmission, a rear axle drive assembly and an energy management system. The front axle power assembly includes an engine and a P1 motor connected to each other. The input end of the three-speed hybrid transmission is connected to the P1 motor through a clutch. The output end of the three-speed hybrid transmission is connected to the front wheels of the vehicle. The rear axle drive assembly is connected to the rear wheels of the vehicle. The rear axle drive assembly includes a P4 motor.

[0009] The three-speed hybrid transmission includes a first-speed gear set, a second-speed gear set, and a third-speed gear set. The speed ratios of the first-speed gear set, the second-speed gear set, and the third-speed gear set are set as i1, i2, and i3, respectively, i1 > 3.5, 1.5 ≤ i2 ≤ 2.2, and 0.8 ≤ i3 ≤ 1.2.

[0010] The three-speed hybrid transmission also includes a main reduction gear set connected to the front wheels of the vehicle, with the speed ratio of the main reduction gear set set being i4, where 3.5≤i4≤4.2.

[0011] The P4 motor is connected to the rear wheel via a reducer.

[0012] When the hybrid drive system is operating in pure electric rear-wheel drive mode, the clutch is disengaged, the engine is off, and the P4 motor drives the rear wheels alone.

[0013] When the hybrid drive system operates in series rear-wheel drive mode, the engine drives the P1 motor to generate electricity, and the generated electricity is used to drive the P4 motor, thereby realizing the rear-wheel drive of the vehicle.

[0014] When the hybrid drive system operates in parallel front-wheel drive mode, the clutch engages, and the engine drives the front wheels through the gearbox; it switches between second and third gear to achieve efficient cruising; at the same time, the P1 motor can adjust the engine torque operating range to ensure that the engine always operates in the efficient range.

[0015] When the hybrid drive system operates in parallel four-wheel drive mode, the engine drives the front wheels through the transmission, and the P4 motor drives the rear wheels.

[0016] The present invention also provides a control method for a hybrid drive system based on a three-speed transmission, comprising:

[0017] By dividing the SOC value range and comprehensively considering vehicle speed, vehicle power demand, short-term discharge power of the power battery pack, and vehicle torque demand parameters, the working status of the engine, the P1 motor, the clutch, the three-speed hybrid transmission, and the P4 motor are controlled to achieve switching between different working modes.

[0018] The switching of the working mode includes engine start and stop control, clutch engagement and disengagement control, gear shifting control, and P4 motor drive and follow-up control.

[0019] In the gear shifting control of the three-speed hybrid transmission, the gears include first gear, second gear and third gear. First gear is the escape gear, with a speed ratio >3.5, used to achieve low-speed parallel four-wheel drive for climbing or getting out of trouble; second gear is used to enter engine direct drive at 40km / h to improve economy; third gear is used for high-speed cruising.

[0020] The engine start and stop control is based on the SOC value range and is achieved by combining the vehicle's required power, required torque, and speed, as detailed below:

[0021] When the SOC value is in the high range, the engine will only start when the power demand of the vehicle is greater than the maximum short-term discharge power allowed by the battery, and will only stop when the power demand of the vehicle is less than the maximum short-term discharge power allowed by the power battery pack.

[0022] When the SOC value is in the middle range, the engine starts when the power demand of the vehicle is greater than the maximum short-term discharge power allowed by the power battery pack, or when the torque demand of the vehicle is greater than 50Nm and the vehicle speed is greater than 30km / h, and stops when the vehicle speed is less than 18km / h.

[0023] When the SOC value is in the low range, the engine starts when the vehicle's required power is greater than the maximum short-term discharge power allowed by the power battery pack, or when the vehicle's required torque is greater than 50 Nm and the vehicle speed is greater than 20 km / h, and stops when the vehicle speed is less than 8 km / h.

[0024] When the SOC value is in the extremely low range, the engine can start in place without stopping.

[0025] When the SOC value is in the high, medium or low range, the clutch engages when the vehicle speed is ≥50km / h, the wheel-side torque is ≥ the minimum parallel torque and the wheel-side torque is ≤ the maximum parallel torque;

[0026] When the SOC value is in the high, medium or low range, the clutch disengages at a vehicle speed ≤40km / h.

[0027] In the gear shifting control, the conditions for entering and exiting first gear are as follows:

[0028] The conditions for entering first gear in parallel four-wheel drive are that the vehicle speed is 0 and there is an input signal for the traction mode command.

[0029] The conditions for exiting the escape mode are: vehicle speed ≥ 10km / h, clutch disengagement, and disengagement into first gear.

[0030] In the gear shifting control, the switching conditions between second and third gear are as follows:

[0031] The conditions for shifting from second to third gear are that the clutch is engaged and the vehicle speed is ≥80km / h;

[0032] The conditions for downshifting from third to second gear are that the clutch is engaged and the vehicle speed is ≤70km / h.

[0033] The range extender power generation control strategies corresponding to different SOC value ranges include:

[0034] When the SOC value is in the high range, the vehicle speed following mode does not generate electricity, while the power battery pack provides power first in the power following mode. When the wheel-side power demand is greater than or equal to the maximum allowable discharge power of the power battery pack, the range extender generates electricity to compensate.

[0035] When the SOC value is in the middle range, the power generation capacity in the vehicle speed following mode is 24kW. After the output limit of the vehicle speed power range, the power generation in the power following mode is the larger of the vehicle demand power and the power based on the vehicle speed limit. When the power following is insufficient due to insufficient discharge capacity, the power of the power battery pack is consumed first, and the range extender compensates for the insufficient power.

[0036] When the SOC value is in the low range, the power generation in the speed-following mode is 28kW. This is combined with the compensation power based on the SOC value. Finally, after the power limit of the vehicle speed, the power demand of the vehicle in the power-following mode is increased by the compensation power based on the SOC value and the power based on the speed limit. When entering the power-following mode due to insufficient discharge power, the power of the power battery pack is consumed first, and then the range extender compensates for it.

[0037] When the SOC value is in the extremely low range, in the vehicle speed following mode, the larger of the vehicle demand power and the 28kW power generation power is added, plus the compensation power based on the SOC value, and finally the power is limited by the vehicle speed. In the power following mode, the vehicle demand power plus the compensation power based on the SOC value plus 5kW is added, and then the larger of the power based on the vehicle speed limit is used for power generation.

[0038] In the aforementioned series range extender power generation strategy, the power restriction needs to be gradually lifted. The formula for lifting the power generation is: P 放 =(P 定 -P 限 )*k+P 限 , where P 放 To release the power output, the unit is kW; P 定 P represents the fixed-point power generation capacity, measured in kW. 限 The power generation after the vehicle speed limit is expressed in kW; k is a coefficient less than or equal to 1, which gradually increases as the SOC value decreases.

[0039] The present invention also provides a vehicle including the aforementioned hybrid drive system based on a three-speed transmission.

[0040] This invention is based on a three-speed hybrid drive system. The dual-motor scheme enables pure electric rear-wheel drive, series rear-wheel drive, parallel front-wheel drive, and four-wheel drive modes. It can enter parallel mode at 0 speed and set an escape gear to ensure that the engine and motor enter parallel mode at low speeds to increase wheel torque. By integrating the three-speed gearbox with the P1 motor and setting the P4 motor to drive the rear wheels, the fuel-saving effect is improved, while the hybrid gearbox size can be reduced, the layout difficulty is reduced, and the layout feasibility is improved. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the hybrid drive system based on a three-speed transmission according to the present invention.

[0042] Figure 2 This is a schematic diagram of the structure of the hybrid drive system based on the three-speed transmission of the present invention when it is operating in pure electric rear-drive mode.

[0043] Figure 3 This is a schematic diagram of the structure of the hybrid drive system based on the three-speed transmission of the present invention when it is operating in series rear drive mode;

[0044] Figure 4 This is a schematic diagram of the structure of the hybrid drive system based on the three-speed transmission of the present invention when it is operating in parallel front drive mode;

[0045] Figure 5 This is a schematic diagram of the structure of the hybrid drive system based on the three-speed transmission of the present invention when it is operating in parallel four-wheel drive;

[0046] Figure 6 It is a control strategy switching control diagram;

[0047] Figure 7 This is a schematic diagram of the power generation point selection for the range extender;

[0048] Figure 8 This is a schematic diagram of the torque working area division of parallel engines in the engine MAP table;

[0049] The markings in the above diagrams are as follows: 1. Engine; 2. P1 motor; 3. Clutch; 4. Front wheel; 5. Rear wheel; 6. First gear set; 7. Second gear set; 8. Third gear set; 9. Main reduction gear set; 10. Reducer; 11. First synchronizer; 12. Second synchronizer; 13. Input shaft; 14. Output shaft; 15. Power battery pack; 16. Dual motor controller; 17. P4 motor. Detailed Implementation

[0050] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0051] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," and similar expressions used in this document are for illustrative purposes only.

[0052] It should be noted that in the following embodiments, the terms "first," "second," and "third" do not represent an absolute distinction in structure and / or function, nor do they represent the order of execution; they are merely for the convenience of description.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0054] Firstly, such as Figures 1 to 5 As shown, this embodiment of the invention provides a hybrid drive system based on a three-speed transmission, including a front axle power assembly, a three-speed hybrid transmission, a rear axle drive assembly, and an energy management system. The front axle power assembly includes an engine and a P1 motor 2 connected to each other. The input end of the three-speed hybrid transmission is connected to the P1 motor 2 via a clutch 3, and the output end of the three-speed hybrid transmission is connected to the front wheels 4 of the vehicle. The rear axle drive assembly is connected to the rear wheels 5 of the vehicle, and the rear axle drive assembly includes a P4 motor 17.

[0055] Specifically, such as Figure 1As shown, in this embodiment of the invention, the P1 motor 2 is integrated with the three-speed hybrid gearbox, which can effectively reduce the volume of the hybrid gearbox and improve layout feasibility. The three-speed hybrid gearbox includes a housing, an input shaft 13, an output shaft 14, a main reduction gear set 9, a first gear set 6, a second gear set 7, and a third gear set 8. The input shaft 13 and the output shaft 14 are rotatably mounted on the housing. The P1 motor 2, the clutch 3, the main reduction gear set 9, the first gear set 6, the second gear set 7, and the third gear set 8 are located inside the housing. The axes of the input shaft 13 and the output shaft 14 are parallel. The input shaft 13 is connected to one end of the clutch 3, and the P1 motor 2 is connected to the other end of the clutch 3. The output end of the engine is connected to the P1 motor 2, and the engine can drive the P1 motor 2 to operate. The engine and the P1 motor 2 are coaxially directly connected through a rigid coupling to form an integrated generator set (i.e., a range extender). The P1 motor 2 integrates three functions: starting, generating, and driving.

[0056] In this embodiment of the invention, the speed ratios of the first gear set 6, the second gear set 7, and the third gear set 8 are set to i1, i2, and i3, respectively, where i1 > 3.5, 1.5 ≤ i2 ≤ 2.2, and 0.8 ≤ i3 ≤ 1.2. The first gear is set as the off-road gear, and its speed ratio > 3.5 enables low-speed parallel four-wheel drive for climbing or getting out of trouble. The second gear enables direct engine drive at speeds up to 40 km / h to improve fuel economy. The third gear is used for high-speed cruising.

[0057] In this embodiment of the invention, the three-speed hybrid transmission further includes a main reduction gear set 9 connected to the front wheels 4 of the vehicle. The speed ratio of the main reduction gear set 9 is set to i4, where 3.5 ≤ i4 ≤ 4.2. The input gear of the main reduction gear set 9 is fixedly connected to the output shaft 14, and the output gear of the main reduction gear set 9 is connected to the front wheels 4 of the vehicle via a drive shaft. The main reduction gear set 9 is used to transmit power from the output shaft 14 to the front wheels 4.

[0058] like Figure 1As shown, in this embodiment of the invention, the first gear set 6 includes a meshing first-gear drive gear and a first-gear driven gear. The first-gear drive gear is fixedly mounted on the input shaft 13, and the first-gear driven gear is loosely fitted on the output shaft 14. The second gear set 7 includes a meshing second-gear drive gear and a second-gear driven gear. The second-gear drive gear is fixedly mounted on the input shaft 13, and the second-gear driven gear is loosely fitted on the output shaft 14. The third gear set 8 includes a meshing third-gear drive gear and a third-gear driven gear. The third-gear drive gear is fixedly mounted on the input shaft 13, the second-gear drive gear is located between the first-gear drive gear and the third-gear drive gear, and the third-gear driven gear is loosely fitted on the output shaft 14. The second-gear driven gear is located between the first-gear driven gear and the third-gear driven gear. A first synchronizer 11 and a second synchronizer 12 are provided on the output shaft 14. The first synchronizer 11 is configured to control the engagement and disengagement of the first-gear driven gear with the output shaft 14, and the second synchronizer 12 is configured to control the engagement and disengagement of the second-gear and third-gear driven gears with the output shaft 14. When the first synchronizer 11 engages the first-gear driven gear with the output shaft 14, the three-speed hybrid transmission is in first gear. When the second synchronizer 12 engages the second-gear driven gear with the output shaft 14, the three-speed hybrid transmission is in second gear. When the second synchronizer 12 engages the third-gear driven gear with the output shaft 14, the three-speed hybrid transmission is in third gear.

[0059] like Figure 1 As shown, in this embodiment of the invention, the P4 motor 17 is connected to the rear wheel 5 through the reducer 10. The input end of the reducer 10 is connected to the P4 motor 17, and the output end of the reducer 10 is connected to the rear wheel 5 of the vehicle through the drive shaft. The reducer 10 is used to transmit power from the P4 motor 17 to the rear wheel 5.

[0060] In this embodiment of the invention, by using P4 motor 17 to replace P3 motor, the hybrid gearbox and P4 motor 17 are mechanically decoupled, and physical coupling is achieved through the connection between the wheels and the ground, achieving the same series-parallel connection mode as P1P3, while supporting front-wheel drive, rear-wheel drive, and four-wheel drive multi-mode driving. Furthermore, a corresponding mode switching control strategy is formulated based on the P1P4 hybrid architecture.

[0061] like Figure 1 As shown, in this embodiment of the invention, the energy management system includes a power battery pack 15 and a dual-motor controller 16. The power battery pack 15 is connected to the controller of motor P1 2 and the controller of motor P4 17 respectively through the dual-motor controller 16.

[0062] like Figure 1As shown, in this embodiment of the invention, when the hybrid drive system operates in pure electric rear-wheel drive mode, clutch 3 is disengaged, the engine is off, P1 motor 2 is not working, and P4 motor 17 drives the rear wheel 5 to rotate independently, thus enabling the vehicle to move. By having P4 motor 17 drive the rear wheel 5 independently, this mode is suitable for low-speed urban driving conditions, achieving zero emissions and effectively reducing environmental pollution.

[0063] like Figure 1 As shown, in this embodiment of the invention, when the hybrid drive system operates in series rear-wheel drive mode, the engine drives motor 2 (P1) to generate electricity. The generated electricity is used to drive motor 17 (P4), which in turn drives the rear wheels 5 to rotate, thus achieving rear-wheel drive of the vehicle. This mode can fully utilize the advantages of the engine and motor under specific operating conditions, improving energy efficiency.

[0064] like Figure 1 As shown, in this embodiment of the invention, when the hybrid drive system operates in parallel front-wheel drive mode, the clutch 3 engages, the engine runs, and the engine drives the front wheels 4 to rotate through the three-speed hybrid transmission, thereby achieving front-wheel drive of the vehicle; the three-speed hybrid transmission switches between second and third gear to achieve efficient cruising; at the same time, the P1 motor 2 can adjust the engine torque operating range to ensure that the engine always operates in the efficient range.

[0065] like Figure 1 As shown, in this embodiment of the invention, when the hybrid drive system operates in parallel four-wheel drive mode, clutch 3 engages, the engine runs, and the engine drives the front wheels 4 to rotate through the three-speed hybrid transmission. Simultaneously, the P4 motor 17 drives the rear wheels 5 to rotate, thereby achieving four-wheel drive. When the three-speed hybrid transmission is in first gear, it is mainly used for extreme road conditions (such as getting out of trouble), providing strong torque output. The three-speed hybrid transmission switches between second and third gear, balancing power and energy consumption, ensuring power performance while reducing energy consumption.

[0066] The hybrid drive system described above features a dual-motor design that enables pure electric rear-wheel drive, series rear-wheel drive, parallel front-wheel drive, and four-wheel drive modes. It can enter parallel mode at 0 speed and has a traction gear to ensure that the engine and motor can enter parallel mode at low speeds to increase wheel torque. By integrating a three-speed gearbox with the P1 motor 2, the P3 motor is replaced with the P4 motor 17, achieving the same fuel-saving effect as the P1P3 architecture, reducing the size of the hybrid gearbox and simplifying its layout.

[0067] Secondly, embodiments of the present invention also provide a control method for a hybrid drive system based on a three-speed transmission, comprising:

[0068] By dividing the SOC (State of Charge) range and comprehensively considering vehicle speed, vehicle power demand, short-term discharge power of power battery pack 15, and vehicle torque demand parameters, the working status of the engine, P1 motor 2, clutch 3, three-speed hybrid transmission and P4 motor 17 are controlled to achieve switching between different working modes.

[0069] The switching of working modes includes engine start and stop control, clutch 3 engagement and disengagement control, gear shifting control, and P4 motor 17 drive and follow-up control.

[0070] In the gear shifting control of the three-speed hybrid transmission, there are three gears: first gear, second gear, and third gear. The first gear is the escape gear, with a speed ratio greater than 3.5, used to achieve low-speed parallel four-wheel drive for climbing or getting out of trouble. The second gear is used to engage engine direct drive at 40km / h to improve fuel economy. The third gear is used for high-speed cruising.

[0071] In this embodiment of the invention, by scientifically dividing the SOC range and comprehensively considering key parameters such as vehicle speed, vehicle power demand, battery short-term discharge power, and vehicle torque demand, the operating states of the engine, P1 motor 2, clutch 3, gear position, and P4 motor 17 are precisely controlled to achieve intelligent switching between different driving modes. The specific control strategy is shown in Table 1 below:

[0072] Table 1 Switching control strategies between different modes

[0073]

[0074]

[0075] In this embodiment of the invention, engine start and stop control is based on the SOC value range and combined with the vehicle's required power, required torque, and speed, as detailed below:

[0076] When the SOC value is in the high range, the engine will only start when the power demand of the vehicle is greater than the maximum short-term discharge power allowed by the battery, and will only stop when the power demand of the vehicle is less than the maximum short-term discharge power allowed by the power battery pack.

[0077] When the SOC value is in the middle range, the engine starts when the vehicle's required power is greater than the maximum short-term discharge power allowed by the power battery pack, or when the vehicle's required torque is greater than 50 Nm and the vehicle speed is greater than 30 km / h, and stops when the vehicle speed is less than 18 km / h.

[0078] When the SOC value is in the low range, the engine starts when the vehicle's required power is greater than the maximum short-term discharge power allowed by the power battery pack, or when the vehicle's required torque is greater than 50 Nm and the vehicle speed is greater than 20 km / h, and stops when the vehicle speed is less than 8 km / h.

[0079] When the SOC value is in the extremely low range, the engine can start in place without stopping.

[0080] When the SOC value is in the high, medium or low range, clutch 3 engages when the vehicle speed is ≥50km / h, the wheel-side torque is ≥ the minimum parallel torque and the wheel-side torque is ≤ the maximum parallel torque;

[0081] When the SOC value is in the high, medium or low range, clutch 3 disengages at a vehicle speed ≤ 40km / h.

[0082] In this embodiment of the invention, the entry and exit conditions for first gear in the gear shifting control are as follows:

[0083] The conditions for entering first gear in parallel four-wheel drive are that the vehicle speed is 0 and there is an input signal for the traction mode command.

[0084] The conditions for exiting the escape mode are: vehicle speed ≥ 10km / h, clutch 3 disengaged and out of first gear.

[0085] In this embodiment of the invention, the switching conditions between second and third gears in the gear shifting control are as follows:

[0086] The conditions for shifting from second to third gear are that clutch 3 is engaged and the vehicle speed is ≥80km / h;

[0087] The conditions for downshifting from third to second gear are that clutch 3 is engaged and the vehicle speed is ≤70km / h.

[0088] In this embodiment of the invention, when the hybrid drive system operates in series rear-wheel drive mode, the engine drives motor 2 (P1) to generate electricity. The series range extender's power generation strategy includes:

[0089] The selection of the generator power output point should ideally be within the high-efficiency range of the range extender's universal characteristics, such as... Figure 6 As shown, the range extender's power generation mode is divided into vehicle speed following mode and power following mode. The specific entry conditions are shown in Table 2 below:

[0090] Table 2. Entry conditions for speed follow and power follow modes

[0091]

[0092] During the process of the engine driving P1 motor 2 to generate electricity, when the total power demand of the vehicle is ≤25kW and the vehicle speed is ≤45km / h, the range extender enters the vehicle speed following mode after a 3-second delay.

[0093] During the process of the engine driving P1 motor 2 to generate electricity, when the total power demand of the whole vehicle is ≥32kW and the vehicle speed is ≥50km / h, the range extender enters the power following mode after a 3-second delay.

[0094] Alternatively, during the process of the engine driving P1 motor 2 to generate electricity, when the total power demand of the vehicle + 5kW power reserve is greater than or equal to the maximum instantaneous discharge power allowed by the power battery pack 15, the range extender enters the power following mode after a 3-second delay, and lasts for at least 5 seconds.

[0095] The speed-following mode is mainly considered under low vehicle speed and low power demand conditions. It limits the power generation by the speed limit in the two-dimensional table (Table 3) to ensure that the engine speed is not too high and to ensure the NVH performance of the vehicle when driving at low speed. The power-following mode is mainly considered under high vehicle speed and high power demand conditions. It allows the range extender to quickly respond to the power demand of the vehicle and avoids the power battery pack's 15SOC from dropping too quickly.

[0096] Table 3 Power Generation Capacity Limits Based on Vehicle Speed

[0097]

[0098] Table 3 shows a two-dimensional power table based on vehicle speed limits. When the vehicle speed is ≤25km / h, the range extender's power output is 8kW; when the vehicle speed reaches 35km / h, the power output is 12kW; when the vehicle speed reaches 45km / h, the power output is 16kW; when the vehicle speed reaches 60km / h, the power output is 18kW; when the vehicle speed reaches 70km / h, the power output is 22kW; when the vehicle speed reaches 80km / h, the power output is 26kW; when the vehicle speed reaches 100km / h, the power output is 28kW; and when the vehicle speed exceeds 100km / h, the power output is 32kW.

[0099] In this embodiment of the invention, as shown in Table 4, the range extender power generation control strategies corresponding to different SOC value ranges include:

[0100] When the SOC value is in the high range, the engine stops and the range extender does not generate electricity in the speed-following mode; in the power-following mode, the power battery pack 15 provides power first, and the range extender generates electricity to compensate when the wheel-side power demand is greater than or equal to the maximum allowable discharge power of the power battery pack 15.

[0101] In this embodiment of the invention, as shown in Table 4, the range extender power generation control strategies corresponding to different SOC value ranges include:

[0102] When the SOC value is in the middle range, in speed-following mode, the range extender's power generation is set to 24kW, which is limited by the power output of the vehicle speed range. In power-following mode, the larger power value is selected between the vehicle's required power and the power based on the vehicle speed limit for power generation. That is, the range extender's power generation is set to the larger power value between the vehicle's required power and the power based on the vehicle speed limit. When the power generation is insufficient for power following, 15% of the power of the battery pack is consumed first, and the range extender compensates for the remaining power.

[0103] The setting of "range extender power generation set at 24kW" is the basic power generation value for this mode. This value is set by comprehensively considering factors such as the power maintenance requirements in the SOC range and the engine's efficient operating range. It aims to provide basic power support for the vehicle while avoiding energy waste due to excessive power generation or the impact of insufficient power generation on the power balance. "Power output limit across vehicle speed range" is a further adjustment of the range extender's power generation. "Vehicle speed power range" refers to the range divided according to different vehicle speed ranges. Each range corresponds to a power generation limit value, as shown in Table 3. The actual power output of the range extender will be limited within the power limit value corresponding to the vehicle speed, ensuring the NVH performance of the vehicle at low speeds and avoiding problems such as low operating efficiency and high vibration and noise of the engine due to power generation mismatch at specific vehicle speeds. This improves the overall performance of the vehicle while taking into account the power balance.

[0104] "Vehicle power demand" refers to the total power required by the vehicle under its current driving conditions, such as acceleration, hill climbing, and maintaining the current speed. It is determined by factors such as driver operation (e.g., accelerator pedal opening) and vehicle rolling resistance. "Power based on vehicle speed limit" is the upper limit of the range extender's power generation determined based on the vehicle's current speed through a preset correspondence (e.g., referring to Table 3). This limit is to ensure the efficient operation of components such as the engine at specific vehicle speeds or to meet performance requirements such as NVH (noise, vibration, and harshness). In actual power generation control, these two power values ​​are compared, and the larger power value is selected as the target power generation of the range extender. This ensures that the vehicle's current power demand is met, while also preventing the range extender's power generation from being too low and deviating from its efficient operating range when the power demand is low, thus meeting the demand while also considering system efficiency.

[0105] Furthermore, when the vehicle is in power-following mode and the battery discharge power is insufficient to meet the vehicle's power requirements (i.e., insufficient discharge power), the drive system will prioritize utilizing the electrical energy stored in the power battery pack 15, allowing the power battery pack 15 to output power to compensate for the demand. This is because the power battery pack 15 can quickly respond to power changes and meet instantaneous power demands. However, when the power output of the power battery pack 15 reaches its maximum allowable discharge power and still cannot meet the vehicle's power requirements, the range extender will activate or increase its power generation to supplement the shortfall, ensuring the vehicle receives sufficient power. This control method fully utilizes the rapid response characteristics of the power battery pack 15 and can supplement its power through the range extender when the power battery pack 15's capacity is insufficient, achieving stable power output and rational energy utilization.

[0106] In this embodiment of the invention, as shown in Table 4, the range extender power generation control strategies corresponding to different SOC value ranges include:

[0107] When the SOC value is in the low range, in speed-following mode, the range extender's power generation is set to the base power plus the compensation power based on the SOC value. The base power is 28kW. Finally, the power limit of the vehicle speed is applied, as shown in Table 3, to determine the upper limit of the range extender's power generation. In power-following mode, the range extender's power generation is set to the vehicle's required power plus the compensation power based on the SOC value. Then, the power based on the vehicle speed limit (as shown in Table 3) is taken as the larger value for power generation. When entering power-following mode due to insufficient discharge power, 15% of the power battery pack's discharge power is consumed first, and then the range extender compensates for it.

[0108] When the SOC value is in the low range, in power follow mode, the range extender's power generation is set to the larger of the power value between the vehicle's required power plus the compensation power based on the SOC value and the power based on the vehicle speed limit.

[0109] In this embodiment of the invention, as shown in Table 4, the range extender power generation control strategies corresponding to different SOC value ranges include:

[0110] When the SOC value is in the extremely low range, in speed-following mode, the range extender's base power generation is set to the larger of the vehicle's required power and the 28kW power generation. The base power generation plus the compensation power based on the SOC value is the range extender's final power generation, which is then reduced by the speed limit power. In power-following mode, the range extender's base power generation is set to the larger of the vehicle's required power, the compensation power based on the SOC value, and 5kW. This is then combined with the power based on the speed limit power for power generation. In other words, the range extender's power generation is set to the larger of the base power generation and the power based on the speed limit (as shown in Table 3).

[0111] In this embodiment of the invention, the high, medium, low, and extremely low SOC ranges are used to divide the remaining charge range of the power battery pack 15. Their core function is to provide a basis for determining the power system control strategy (such as engine start-stop, range extender power generation, and drive mode switching) under different charge states. When the SOC value is in the high range, the power battery pack 15 has sufficient charge, and the system prioritizes power supply from the power battery pack 15. When the SOC value is in the medium range, the power battery pack 15 has a moderate charge, requiring a balance between power performance and charge maintenance. When the SOC value is in the low range, the power battery pack 15 has a low charge, requiring enhanced charge retention. When the SOC value is in the extremely low range, the power battery pack 15 is nearly depleted, and charge retention becomes the primary objective. The engine needs to be started in place without stopping, the range extender's power generation is further increased, and priority is given to meeting power generation needs to avoid over-discharge of the power battery pack 15.

[0112] In this embodiment of the invention, because the speed-following mode imposes a speed-based power limit on the generator, resulting in poor low-SOC power retention, the power limit needs to be gradually increased to allow the range extender to output higher power output, thereby enhancing power retention. Therefore, when the hybrid drive system operates in series rear-wheel drive mode, the engine drives motor 2 (P1) to generate electricity, which is then used to drive motor 4 (P4) or charge the battery. The battery charge is balanced by adjusting the power output. In the series range extender power generation strategy, the power limit of the range extender needs to be gradually increased, and the power output of the range extender is set to P... 放 Release power P 放 The calculation formula is:

[0113] P 放 =(P 定 -P 限 )*k+P 限 , where P 放 To release the power output, the unit is kW; P 定 P is the theoretically required power output of a range extender at a specific vehicle speed to meet power supply or other energy demands, measured in kW. 限 This represents the generated power output after the vehicle speed limit, i.e., the upper limit of power obtained from the table based on the vehicle speed, in kW; k is a coefficient less than or equal to 1, which gradually increases as the SOC value decreases. When the SOC is at a low level, the k value is small, and P... 放 Approaching P 限 The relaxation of restrictions is small; as SOC further decreases (closer to the extremely low range), the value of k increases, (P 定 -P 限 The portion of )*k increases accordingly, P 放 Gradually approaching P 定 This means that the power limit has been significantly lifted, and the range extender can output power closer to P. 定 This increases the power generation capacity, thereby enhancing the power supply guarantee effect.

[0114] In this embodiment of the invention, when the hybrid drive system operates in parallel front-wheel drive mode, clutch 3 is engaged, the engine runs, and the engine drives the front wheels 4 to rotate through a three-speed hybrid transmission. At this time, the engine torque output needs to follow dynamic control logic based on SOC range division. The engine torque output strategy in parallel front-wheel drive mode includes:

[0115] Through three preset torque lines (T1 torque line, T2 torque line, T3 torque line, such as...) Figure 7 The engine torque output range is divided into different regions (as shown in the engine MAP table). These torque lines are set based on factors such as the engine's efficient operating range and battery power requirements. The T3 torque line may correspond to the higher torque range where the engine operates efficiently, the T2 torque line is the medium torque range, and the T1 torque line is the lower torque range.

[0116] The engine's actual torque output is dynamically adjusted by P1 motor 2; P1 motor 2 can output positive or negative torque to assist the engine in accurately matching the target torque, ensuring that the engine operates stably within the set torque range, while achieving a smooth power transition.

[0117] In parallel mode, the engine torque operates in regions divided by three torque lines. Figure 7 Different SOC ranges correspond to different torque ranges for the engine, and the engine torque is adjusted by motor P1 2.

[0118] Table 4 Torque operating range of engines with different SOCs

[0119] SOC range Torque range Remark high Take the T3 line Ensure the engine operates in its high-efficiency range middle Take the T2 to T3 section It needs to have a certain SOC power retention capability. Low Take the T1 to T3 route Further enhance SOC power retention capabilities Extremely low Exit parallel connection Entering series connection further enhances SOC power retention.

[0120] As shown in Table 4, when the SOC value is in the high range, the power battery pack 15 has sufficient charge, and the engine prioritizes operating in the torque region corresponding to the T3 torque line. This region is the engine's high-efficiency zone, which can minimize fuel consumption. At this time, there is no need to deliberately conserve battery power; fuel economy is the priority.

[0121] As shown in Table 4, when the SOC value is in the middle range, the power battery pack 15 has a moderate charge, and the engine torque is adjusted between the T2 and T3 torque lines. Compared to the high SOC range, appropriately lowering the upper limit of torque, while maintaining a certain power output, also prevents the power battery pack 15 from depleting too quickly by reasonably controlling the engine output, thus achieving the basic power preservation function.

[0122] As shown in Table 4, when the SOC value is in the low range, the power battery pack 15 has a low charge, and the engine torque extends to the T1-T3 torque line. Further relaxing the lower limit of torque allows the engine to operate in a lower torque range, and by intervening more frequently in direct drive or power generation, it strengthens the charging and replenishment of the power battery pack 15, thereby improving the power retention capability.

[0123] As shown in Table 4, when the SOC value is in the extremely low range, the power battery pack 15 is almost depleted. At this time, the engine exits the parallel mode and enters the series mode. The engine drives the P1 motor 2 to generate electricity at full capacity, prioritizing the replenishment of the power battery pack 15 to avoid over-discharge and making power preservation the primary goal.

[0124] In this embodiment of the invention, when the hybrid drive system operates in parallel four-wheel drive mode, clutch 3 engages, the engine runs, and the engine drives the front wheels 4 to rotate through a three-speed hybrid transmission. Simultaneously, P4 motor 17 drives the rear wheels 5 to rotate. The strategy for controlling the torque output of P4 motor 17 at this time includes:

[0125] The torque output of motor 17 in P4 is dynamically distributed through a set algorithm, the formula of which is:

[0126] T_p4 = min(T_d × K_v, T_max), where K_v = 1 - (V / 120)^2, T_p4 is the output torque of P4 motor 17 in N·m; T_d is the required torque of the whole vehicle in N·m; V is the current vehicle speed in km / h; and T_max is the maximum output torque of P4 motor 17 in N·m.

[0127] The output torque of motor P417 is taken as the smaller value between "T_d×K_v" and "T_max". With this setting, the torque ratio of the rear wheels 5 can be dynamically adjusted according to the vehicle speed.

[0128] Low-speed conditions (such as starting, climbing, and getting out of trouble): The vehicle speed is low, the K_v value is large (close to 1), and T_d×K_v is close to the torque required by the whole vehicle. The P4 motor 17 can output a large torque, which, together with the engine power of the front wheel 4, realizes four-wheel drive and improves the vehicle's power and passability.

[0129] High-speed conditions (such as high-speed cruising): At high vehicle speeds, the K_v value is small (close to 0), T_d×K_v decreases significantly, and the output torque of the P4 motor (17) decreases or even stops. In this situation, the vehicle primarily relies on the engine to directly drive the front wheels (4) through high gear, reducing motor energy consumption and improving fuel economy at high speeds.

[0130] At the same time, by limiting T_max, the output of P4 motor 17 is ensured not to exceed its hardware limit, thus avoiding motor overload damage.

[0131] The two torque output strategies mentioned above are for the engine and the P4 motor 17, respectively. By combining parameters such as SOC status, vehicle speed, and vehicle torque requirements, the power distribution under different operating conditions is optimized, which not only ensures power performance under complex road conditions, but also takes into account economy and safety of the power battery pack 15 under different charge states.

[0132] The hybrid drive system and control method described above have the following advantages:

[0133] 1. Three-speed transmission with integrated hybrid function: the first gear is dedicated to low-speed, high-torque scenarios (such as getting out of trouble), and can achieve parallel four-wheel drive at 0 speed; the second and third gears optimize high-speed efficiency.

[0134] 2. Compact hybrid box size: Eliminating the P3 motor reduces the size of the hybrid box, which is beneficial for the layout of the engine compartment and requires less space.

[0135] 3. Mode switching strategy: Automatically selects gear and drive mode based on vehicle speed, torque, power demand and SOC status, making mode switching intelligent;

[0136] 4. By integrating a three-speed gearbox with the P1P4 architecture, the structure is simplified, efficiency is improved, and adaptability to multiple scenarios is achieved, making it especially suitable for SUVs, pickup trucks, vans, and other vehicle types.

[0137] The present invention also provides a vehicle including a hybrid power drive system with the above-described structure. The vehicle is a hybrid electric vehicle, such as an SUV, pickup truck, or van. This hybrid power drive system can be referenced from [reference needed]. Figures 1 to 5 Further details will not be elaborated here. Since the vehicle of the present invention includes the hybrid drive system described in the above embodiments, it possesses all the advantages of the aforementioned hybrid drive system.

[0138] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A hybrid drive system based on a three-speed transmission, characterized in that, It includes a front axle powertrain, a three-speed hybrid transmission, a rear axle drivetrain, and an energy management system. The front axle powertrain includes a connected engine and a P1 motor. The input end of the three-speed hybrid transmission is connected to the P1 motor via a clutch, and the output end of the three-speed hybrid transmission is connected to the front wheels of the vehicle. The rear axle drivetrain is connected to the rear wheels of the vehicle and includes a P4 motor. The three-speed hybrid transmission includes a first-speed gear set, a second-speed gear set, and a third-speed gear set. The speed ratios of the first-speed gear set, the second-speed gear set, and the third-speed gear set are set as i1, i2, and i3, respectively, i1 > 3.5, 1.5 ≤ i2 ≤ 2.2, and 0.8 ≤ i3 ≤ 1.

2.

2. The hybrid drive system based on a three-speed transmission according to claim 1, characterized in that, The three-speed hybrid transmission also includes a main reduction gear set connected to the front wheels of the vehicle, with the speed ratio of the main reduction gear set set being i4, where 3.5≤i4≤4.

2.

3. The hybrid drive system based on a three-speed transmission according to claim 1, characterized in that, The P4 motor is connected to the rear wheel via a reducer.

4. The hybrid drive system based on a three-speed transmission according to any one of claims 1 to 3, characterized in that, When the hybrid drive system is operating in pure electric rear-wheel drive mode, the clutch is disengaged, the engine is off, and the P4 motor drives the rear wheels alone. When the hybrid drive system operates in series rear-wheel drive mode, the engine drives the P1 motor to generate electricity, and the generated electricity is used to drive the P4 motor, thereby realizing the rear-wheel drive of the vehicle. When the hybrid drive system operates in parallel front-wheel drive mode, the clutch engages, and the engine drives the front wheels through the gearbox; it switches between second and third gear to achieve efficient cruising; at the same time, the P1 motor can adjust the engine torque operating range to ensure that the engine always operates in the efficient range. When the hybrid drive system operates in parallel four-wheel drive mode, the engine drives the front wheels through the transmission, and the P4 motor drives the rear wheels.

5. The control method for a hybrid drive system based on a three-speed transmission according to any one of claims 1 to 4, characterized in that, include: By dividing the SOC value range and comprehensively considering vehicle speed, vehicle power demand, short-term discharge power of the power battery pack, and vehicle torque demand parameters, the working status of the engine, the P1 motor, the clutch, the three-speed hybrid transmission, and the P4 motor are controlled to achieve switching between different working modes. The switching of the working mode includes engine start and stop control, clutch engagement and disengagement control, gear shifting control, and P4 motor drive and follow-up control. In the gear shifting control of the three-speed hybrid transmission, the gears include first gear, second gear and third gear. First gear is the escape gear, with a speed ratio >3.5, used to achieve low-speed parallel four-wheel drive for climbing or getting out of trouble; second gear is used to enter engine direct drive at 40km / h to improve economy; third gear is used for high-speed cruising.

6. The control method for a hybrid drive system based on a three-speed transmission according to claim 5, characterized in that, The engine start and stop control is based on the SOC value range and is achieved by combining the vehicle's required power, required torque, and speed, as detailed below: When the SOC value is in the high range, the engine will only start when the power demand of the vehicle is greater than the maximum short-term discharge power allowed by the battery, and will only stop when the power demand of the vehicle is less than the maximum short-term discharge power allowed by the power battery pack. When the SOC value is in the middle range, the engine starts when the power demand of the vehicle is greater than the maximum short-term discharge power allowed by the power battery pack, or when the torque demand of the vehicle is greater than 50Nm and the vehicle speed is greater than 30km / h, and stops when the vehicle speed is less than 18km / h. When the SOC value is in the low range, the engine starts when the vehicle's required power is greater than the maximum short-term discharge power allowed by the power battery pack, or when the vehicle's required torque is greater than 50 Nm and the vehicle speed is greater than 20 km / h, and stops when the vehicle speed is less than 8 km / h. When the SOC value is in the extremely low range, the engine can start in place without stopping.

7. The control method for a hybrid drive system based on a three-speed transmission according to claim 5, characterized in that, When the SOC value is in the high, medium or low range, the clutch engages when the vehicle speed is ≥50km / h, the wheel-side torque is ≥ the minimum parallel torque and the wheel-side torque is ≤ the maximum parallel torque; When the SOC value is in the high, medium or low range, the clutch disengages at a vehicle speed ≤40km / h.

8. The control method for a hybrid drive system based on a three-speed transmission according to any one of claims 5 to 7, characterized in that, In the gear shifting control, the conditions for entering and exiting first gear are as follows: The conditions for entering first gear in parallel four-wheel drive are that the vehicle speed is 0 and there is an input signal for the traction mode command. The conditions for exiting the escape mode are: vehicle speed ≥ 10km / h, clutch disengagement, and disengagement into first gear.

9. The control method for a hybrid drive system based on a three-speed transmission according to any one of claims 5 to 7, characterized in that, In the gear shifting control, the switching conditions between second and third gear are as follows: The conditions for shifting from second to third gear are that the clutch is engaged and the vehicle speed is ≥80km / h; The conditions for downshifting from third to second gear are that the clutch is engaged and the vehicle speed is ≤70km / h.

10. The control method for a hybrid drive system based on a three-speed transmission according to any one of claims 5 to 7, characterized in that, The range extender power generation control strategies corresponding to different SOC value ranges include: When the SOC value is in the high range, the vehicle speed following mode does not generate electricity, while the power battery pack provides power first in the power following mode. When the wheel-side power demand is greater than or equal to the maximum allowable discharge power of the power battery pack, the range extender generates electricity to compensate. When the SOC value is in the middle range, the power generation capacity in the vehicle speed following mode is 24kW. After the output limit of the vehicle speed power range, the power generation in the power following mode is the larger of the vehicle demand power and the power based on the vehicle speed limit. When the power following is insufficient due to insufficient discharge capacity, the power of the power battery pack is consumed first, and the range extender compensates for the insufficient power. When the SOC value is in the low range, the power generation in the speed-following mode is 28kW. This is combined with the compensation power based on the SOC value. Finally, after the power limit of the vehicle speed, the power demand of the vehicle in the power-following mode is increased by the compensation power based on the SOC value and the power based on the speed limit. When entering the power-following mode due to insufficient discharge power, the power of the power battery pack is consumed first, and then the range extender compensates for it. When the SOC value is in the extremely low range, in the vehicle speed following mode, the larger of the vehicle demand power and the 28kW power generation power is added, plus the compensation power based on the SOC value, and finally the power is limited by the vehicle speed. In the power following mode, the vehicle demand power plus the compensation power based on the SOC value plus 5kW is added, and then the larger of the power based on the vehicle speed limit is used for power generation.

11. The control method for a hybrid drive system based on a three-speed transmission according to claim 10, characterized in that, In the aforementioned series range extender power generation strategy, the power restriction needs to be gradually lifted. The formula for lifting the power generation is: P 放 =(P 定 -P 限 )*k+P 限 , where P 放 To release the power output, the unit is kW; P 定 P represents the fixed-point power generation capacity, measured in kW. 限 The power generation after the vehicle speed limit is expressed in kW; k is a coefficient less than or equal to 1, which gradually increases as the SOC value decreases.

12. A vehicle, characterized in that, Includes the hybrid drive system based on a three-speed transmission as described in any one of claims 1 to 4.

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