Four-speed hybrid transmission, hybrid vehicle and control method

Abstract

The present invention provides a four-speed hybrid transmission, a hybrid vehicle, and a control method. The four-speed hybrid transmission of the present invention includes an input shaft, a first output shaft, and a second output shaft arranged in parallel. A first driving gear and a second driving gear are spaced apart on the input shaft. A first-gear driven gear, a second-gear driven gear, and a first shifting mechanism are mounted on the first output shaft. A third-gear driven gear, a fourth-gear driven gear, and a second shifting mechanism are mounted on the second output shaft. The first-gear driven gear and the third-gear driven gear are both meshed and connected with the first driving gear, and the second-gear driven gear and the fourth-gear driven gear are both meshed and connected with the second driving gear. The four-speed hybrid transmission of the present invention can significantly reduce the number of transmission gears arranged in the axial direction of the transmission, thereby effectively reducing the axial dimension of the transmission.

Description

Technical Field

[0001] The present invention relates to the technical field of hybrid vehicles, and in particular to a four-speed hybrid transmission. Furthermore, the present invention also relates to a hybrid vehicle and a control method. Background Art

[0002] With the rapid development of the automotive industry, the country has increasingly higher requirements for the economy and emissions of automobiles. Due to the excellent power, economy and effective reduction of exhaust emissions of hybrid vehicles, hybrid vehicles have become a rapidly developing type of vehicle in the automotive field; the research and development investment in hybrid system architecture in this field is also increasing.

[0003] There are numerous hybrid transmissions on the market, and they have been applied to various passenger vehicle models. However, existing hybrid transmission systems still have many shortcomings in terms of gear configuration, drive mode settings, and drive mode control. For example, common transmission gears are single or double, which are relatively low gears, resulting in poor vehicle power and economy during starting. Furthermore, the overall powertrain has limited control modes, and most hybrid transmissions are front-wheel drive, with a relatively simple drive mode. This lacks appropriate drive control strategies for handling special operating conditions, resulting in poor vehicle dynamic performance and drivability.

[0004] At the same time, when the vehicle is in complex road conditions such as mud, rain and snow, it needs to switch to four-wheel drive mode in real time. However, the existing control strategy lacks consideration of the actual torque requirements of the wheels, and often cannot accurately and effectively play the role of the four-wheel drive mode, resulting in unnecessary frequent switching between two-wheel drive and four-wheel drive.

[0005] In addition, with the increasing demand for intelligent driving assistance functions, existing intelligent assisted driving technologies have been widely used in automobiles. However, in the existing control algorithms such as adaptive cruise control and other intelligent assisted driving, vehicle following warning and protection, there are problems such as complex calculation logic and large control calculation volume; therefore, there is also room and need for continuous optimization and improvement.

[0006] Based on the above situation, it is necessary to conduct targeted and in-depth research on the driving control strategies and methods of the power system, in order to continuously optimize and improve the driving economy and comprehensive driving performance of hybrid vehicles. Summary of the Invention

[0007] In view of this, the present invention aims to provide a four-speed hybrid transmission to effectively reduce the axial size of the transmission.

[0008] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0009] A four-speed hybrid transmission comprises an input shaft, a first output shaft, and a second output shaft arranged in parallel; a first driving gear and a second driving gear are spaced apart on the input shaft; a first-gear driven gear, a second-gear driven gear, and a first shifting mechanism selectively engaging with the first-gear driven gear or the second-gear driven gear are mounted on the first output shaft; a third-gear driven gear, a fourth-gear driven gear, and a second shifting mechanism selectively engaging with the third-gear driven gear or the fourth-gear driven gear are mounted on the second output shaft; the first-gear driven gear and the third-gear driven gear are both meshed and connected with the first driving gear, and the second-gear driven gear and the fourth-gear driven gear are both meshed and connected with the second driving gear.

[0010] Furthermore, the input shaft includes a first input shaft and a second input shaft mounted on the first input shaft, the first driving gear is fixed on the first input shaft, and the second driving gear is fixed on the second input shaft; the end of the input shaft is provided with a first clutch for receiving power input, and the first clutch can selectively engage the first input shaft or the second input shaft.

[0011] Furthermore, the four-speed hybrid transmission is integrated with a first motor, and the first motor is connected to the input shaft via the first clutch.

[0012] Furthermore, a first output gear is provided on the first output shaft, and a second output gear is provided on the second output shaft. The first output gear is meshed and connected with the second output gear, and the second output gear is used for power output.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] The four-speed hybrid transmission of the present invention arranges the input shaft, the first output shaft, and the second output shaft in parallel, provides a two-speed shift gear set between the input shaft and the first output shaft, and provides another two-speed shift gear set between the input shaft and the second output shaft. At the same time, the two driving gears on the input shaft can be shared by the two shift gear sets respectively. This arrangement can greatly reduce the number of transmission gears set in the axial direction of the four-speed hybrid transmission, thereby effectively reducing the axial size of the transmission.

[0015] In addition, the input shaft adopts the form of a first input shaft and a second input shaft set, which can disengage gears that do not need to rotate according to the needs of different gear transmission routes, thereby reducing mechanical losses during power transmission and helping to improve the transmission efficiency of the four-speed hybrid transmission.

[0016] Another object of the present invention is to provide a hybrid vehicle comprising an engine and a first motor for driving front axle wheels, a second motor for driving rear axle wheels, and a battery connecting the first motor and the second motor; the hybrid vehicle is equipped with the four-speed hybrid transmission described in the present invention, and the engine and the first motor both transmit power to the front axle wheels through the four-speed hybrid transmission.

[0017] The hybrid vehicle of the present invention has the technical advantages of the above-mentioned four-speed hybrid transmission; at the same time, the arrangement of the engine, the first motor and the second motor, combined with the use of the four-speed hybrid transmission, form a good four-wheel drive hybrid architecture, which is conducive to improving the driving performance of the hybrid vehicle.

[0018] In addition, the present invention also proposes a control method for the hybrid vehicle of the present invention, the control method comprising:

[0019] Configuring multiple operating modes for the vehicle by matching different operating states of the engine, the first motor, and the second motor, and setting multiple preset conditions related to operating parameters of the vehicle corresponding to each operating mode;

[0020] The changes of the operating parameters are acquired in real time, and the vehicle is controlled to operate in the operating mode corresponding to the preset conditions that the operating parameters meet.

[0021] Furthermore, the operating parameters include the battery power obtained by detecting the battery, and the operating modes include a pure electric mode in which the vehicle is driven by the first motor and / or the second motor, an engine mode in which the engine provides power output, and a hybrid mode in which the vehicle is driven by the engine in cooperation with the first motor or the second motor; the preset conditions include a first power value and a second power value set in sequence from high to low, the pure electric mode is executed when the battery power is above the first power value, the engine mode is executed when the battery power is below the second power value, and the hybrid mode is executed when the battery power is between the first power value and the second power value.

[0022] Furthermore, the operating mode includes a launch control mode, and the operating parameter includes an accelerator pedal opening; in the launch control mode, the engine and the first motor jointly drive the front axle wheels, and the second motor drives the rear axle wheels; the preset condition includes a set opening value, and when the accelerator pedal opening reaches the set opening value, the launch control mode is executed.

[0023] Furthermore, the operating mode includes an energy recovery mode in which the first motor is driven by the front axle wheels and / or the second motor is driven by the rear axle wheels to generate electricity. The operating parameters include a vehicle status signal for determining whether the vehicle is in a braking or coasting state, and a following distance. When any of the following preset conditions is met, the vehicle executes the energy recovery mode:

[0024] The vehicle is in a braking or coasting state;

[0025] The following distance falls within a preset following distance range.

[0026] Furthermore, it also includes an output torque limiting strategy executed during the process of switching from two-wheel drive mode to four-wheel drive mode, and an output torque correction strategy executed when there is a vehicle within a set distance range in front;

[0027] The output torque limiting strategy includes: determining whether there is a torque input demand from the driven wheel, and switching from the two-wheel drive mode to the four-wheel drive mode only when the driven wheel has a torque input demand;

[0028] The output torque correction strategy includes: obtaining the speed of the preceding vehicle, the speed of the host vehicle and the following distance, and presetting a following safety distance; calculating the allowable safe acceleration for maintaining the following distance above the following safety distance based on the speed of the preceding vehicle, the speed of the host vehicle, the following distance and the following safety distance; and correcting the output torque determined based on the change in the accelerator pedal opening to control the actual acceleration obtained by the actual output torque to be below the safety acceleration.

[0029] The control method of the present invention is based on the configuration of the engine, the first motor and the second motor. By driving the three drive components in different operating states in coordination, different operating modes such as front-wheel drive, rear-wheel drive, four-wheel drive, pure electric, and hybrid can be configured for the vehicle to cope with different operating conditions and driving requirements of the vehicle. By detecting and acquiring the vehicle's operating parameters in real time, the vehicle's current appropriate operating mode can be determined, thereby controlling the vehicle to operate in a suitable operating mode, which is beneficial to improving the comprehensive driving efficiency of the hybrid vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention. Terms such as front and back, top and bottom, etc., used therein are intended only to indicate relative positional relationships and do not constitute undue limitations on the present invention. In the accompanying drawings:

[0031] Figure 1 Schematic diagram of the system structure of the four-speed hybrid transmission and the power system of the hybrid vehicle according to the first embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the overall operation mode control logic of the hybrid vehicle control method according to the third embodiment of the present invention;

[0033] Figure 3 Schematic diagram of the control logic for determining the output torque limiting strategy according to the third embodiment of the present invention;

[0034] Figure 4 This is a control logic diagram of the output torque correction strategy according to the third embodiment of the present invention;

[0035] Figure 5 Schematic diagram comparing the output torque curves of the vehicle before and after correction according to the third embodiment of the present invention.

[0036] Description of reference numerals:

[0037] 11. Front axle wheels; 12. Rear axle wheels;

[0038] 20. Engine; 21. First motor; 22. Second motor; 220. Reducer; 23. Third motor; 24. Differential; 25. Battery;

[0039] 301, first input shaft; 302, second input shaft; 303, first driving gear; 304, second driving gear; 311, first output shaft; 312, second output shaft; 321, first gear driven gear; 322, second gear driven gear; 323, third gear driven gear; 324, fourth gear driven gear; 325, first output gear; 326, second output gear; 327, front axle gear; 33, motor drive gear set;

[0040] 410 , second clutch; 411 , first clutch; 421 , first shift mechanism; 422 , second shift mechanism. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0042] In the description of the present invention, it should be stated that if terms such as "up, down, left, right, front, back, inside, outside" that indicate directions or positional relationships appear, they are based on the directions or positional relationships shown in the accompanying drawings and are only used to facilitate the description of the present invention. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed or operate in a specific direction. Therefore, they should not be understood as limiting the present invention. Taking the automobile described in the present invention as an example, the direction words such as "up, down, left, right, front, back" used in the embodiments are defined based on the vehicle's up and down direction (also known as the height direction), left and right direction (also known as the width direction) and front and back direction (also known as the length direction). Specifically, as shown in the accompanying drawings, the X direction is the vehicle's front and back direction, wherein the side to which the arrow points is "front" and the opposite is "back". The Y direction is the vehicle's left and right direction, wherein the side to which the arrow points is "left" and the opposite is "right". The Z direction is the vehicle's up and down direction, wherein the side to which the arrow points is "up" and the opposite is "down". "Inside" and "outside" are defined based on the outline of the corresponding components. For example, "inside" and "outside" are defined based on the vehicle outline. The side of the vehicle outline close to the middle of the vehicle is "inside", and the opposite side is "outside".

[0043] In addition, in the description of the present invention, unless otherwise clearly defined, the terms "installed", "connected", "connection", and "connector" should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or a connection between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in combination with specific circumstances. The limiting terms such as "first, second, A, B, C, D" that appear in the description of the present invention are only used to distinguish similar features of different positions, affiliations or uses, so as to achieve the purpose of avoiding ambiguity and confusion, and cannot be understood as indicating or implying relative importance.

[0044] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0045] Example 1

[0046] This embodiment relates to a four-speed hybrid transmission, which can effectively reduce the axial size of the transmission; an exemplary structure thereof is as follows Figure 1 shown.

[0047] Generally speaking, the four-speed hybrid transmission includes a parallel input shaft, a first output shaft 311, and a second output shaft 312. A first driving gear 303 and a second driving gear 304 are spaced apart on the input shaft. The first output shaft 311 is fitted with a first-gear driven gear 321, a second-gear driven gear 322, and a first shift mechanism 421 that selectively engages with either the first-gear driven gear 321 or the second-gear driven gear 322. The second output shaft 312 is fitted with a third-gear driven gear 323, a fourth-gear driven gear 324, and a second shift mechanism 422 that selectively engages with either the third-gear driven gear 323 or the fourth-gear driven gear 324. The first-gear driven gear 321 and the third-gear driven gear 323 are both meshed and connected with the first driving gear 303, while the second-gear driven gear 322 and the fourth-gear driven gear 324 are both meshed and connected with the second driving gear 304.

[0048] Specifically, if Figure 1 As shown in , the input shaft of this embodiment includes a first input shaft 301 and a second input shaft 302 mounted on the first input shaft 301. A first driving gear 303 is fixedly mounted on the first input shaft 301, and a second driving gear 304 is fixedly mounted on the second input shaft 302. Furthermore, a first clutch 411 is provided at the end of the input shaft for receiving power input. The first clutch 411 can selectively engage the first input shaft 301 or the second input shaft 302. The arrangement of the first input shaft 301 and the second input shaft 302 allows for the disengagement of gears not required for rotation according to the needs of different gear transmission routes, thereby reducing mechanical losses during power transmission and improving the transmission efficiency of the four-speed hybrid transmission.

[0049] In actual implementation, the engine 20 for power input can be connected to the input shaft via the first clutch 411. Alternatively, the first motor 21, serving as the P2 motor, can be integrated into a four-speed hybrid transmission, connected to the input shaft via the first clutch 411; simultaneously, the engine 20 is connected to the first motor 21 via the second clutch 410. With this arrangement, power can be input to the input shaft from both the engine 20 and the first motor 21, or the first motor 21 can be input to the input shaft by disengaging the second clutch 410. Alternatively, the first clutch 411 can be disengaged and the second clutch 410 engaged, allowing the engine 20 to drive the first motor 21 to generate electricity for the battery 25.

[0050] It should be noted that the above-mentioned first clutch 411 and second clutch 410 can adopt various types of cutting mechanisms such as ordinary clutches and dog clutches for power cutting and engaging; the first gear shifting mechanism 421 and the second gear shifting mechanism 422 can adopt gear shifting mechanisms such as synchronizers in conjunction with gear shifting motors to realize gear switching actions.

[0051] Meanwhile, a first output gear 325 is provided on the first output shaft 311 , and a second output gear 326 is provided on the second output shaft 312 . The first output gear 325 is meshed and connected with the second output gear 326 , and the second output gear 326 is used for power output.

[0052] In summary, the four-speed hybrid transmission of this embodiment arranges the input shaft, the first output shaft 311, and the second output shaft 312 in parallel, provides a two-speed shift gear set between the input shaft and the first output shaft 311, and provides another two-speed shift gear set between the input shaft and the second output shaft 312. At the same time, the two driving gears on the input shaft can be shared by the two shift gear sets respectively. This arrangement can greatly reduce the number of transmission gears set in the axial direction of the four-speed hybrid transmission, thereby effectively reducing the axial size of the transmission.

[0053] Example 2

[0054] This embodiment relates to a hybrid vehicle, which has an engine 20 and a first motor 21 for driving the front axle wheels 11, a second motor 22 for driving the rear axle wheels 12, and a battery 25 connected to the first motor 21 and the second motor 22; at the same time, the hybrid vehicle is equipped with the four-speed hybrid transmission provided in the first embodiment, and the engine 20 and the first motor 21 both transmit power to the front axle wheels 11 through the four-speed hybrid transmission.

[0055] The engine 20, first motor 21, and input shaft are coaxially arranged. The first motor 21 is integrated into the four-speed hybrid transmission and functions as the P2 motor. This arrangement, combined with the four-speed hybrid transmission, creates a robust four-wheel-drive hybrid architecture, enhancing the hybrid vehicle's driving performance.

[0056] Still Figure 1 As shown, the hybrid vehicle of this embodiment has a differential 24 installed on the drive shaft of the front axle wheels 11. The second output gear 326 meshes with the front axle gear 327 on the differential 24 to output power to the front axle wheels 11. The second motor 22 drives the rear axle wheels 12 via the speed reducer 220. Of course, a third motor 23 can also be added to the hybrid vehicle's powertrain. Furthermore, a motor transmission gear set 33 is provided at the end of the first input shaft 301 away from the first clutch 411. The motor transmission gear set 33 receives power input from the third motor 23. This allows for various dual-motor drive configurations to be configured for driving the front axle wheels 11, such as P2+P3, P2+P2.5, or P2.5+P3.

[0057] Based on the configuration of the four-speed hybrid transmission of the first embodiment, a four-speed transmission mechanism is formed in the drive structure for the front axle wheels 11. When the front axle wheels 11 need to be driven in first gear (G1), the first clutch 411 engages the first input shaft 301, and the first shift mechanism 421 engages the first-gear driven gear 321. Power then passes through the first input shaft 301, the first driving gear 303, the first-gear driven gear 321, the first output shaft 311, the first output gear 325, the second output gear 326, and the front axle gear 327 to reach the differential 24, thereby driving the front axle wheels 11. When the front axle wheels 11 need to be driven in second gear (G2), the first clutch 411 engages the second input shaft 302, and the first shift mechanism 421 engages the second-gear driven gear 322. Power then passes through the second input shaft 302, the second driving gear 304, the second-gear driven gear 322, the first output shaft 311, the first output gear 325, the second output gear 326, and the front axle gear 327 to the differential 24, thereby driving the front axle wheels 11. When the front axle wheels 11 need to be driven in third gear (G3), the first clutch 411 engages the first input shaft 301, and the second shift mechanism 422 engages the third-gear driven gear 323. Power then passes through the first input shaft 301, the first driving gear 303, the third-gear driven gear 323, the second output shaft 312, the second output gear 326, and the front axle gear 327 to the differential 24, thereby driving the front axle wheels 11. When the front axle wheels 11 need to be driven in fourth gear (G4), the first clutch 411 engages the second input shaft 302, and the second shift mechanism 422 engages the fourth-gear driven gear 324. The power passes through the second input shaft 302, the second driving gear 304, the fourth-gear driven gear 324, the second output shaft 312, the second output gear 326, and the front axle gear 327 in sequence to reach the differential 24, thereby driving the front axle wheels 11 to operate.

[0058] The hybrid vehicle of this embodiment utilizes a four-speed hybrid transmission, significantly reducing the number of transmission gears in the transmission's axial direction, thereby effectively reducing the transmission's axial dimensions. Furthermore, by equipping the front wheels 11 with an engine 20 and a first motor 21, and the rear wheels 12 with a second motor 22, a comprehensive hybrid four-wheel drive system is achieved.

[0059] Example 3

[0060] This embodiment relates to a control method for implementing the driving control of a hybrid vehicle. An exemplary control logic of the control method is as follows: Figure 2 shown.

[0061] In general, the control method includes: configuring multiple operating modes for the vehicle by matching the different operating states of the engine 20, the first motor 21 and the second motor 22, and setting multiple preset conditions related to the vehicle's operating parameters for each operating mode; then, obtaining the changes in the operating parameters in real time, and controlling the vehicle to operate in the operating mode corresponding to the preset conditions that the operating parameters meet.

[0062] With reference to the power system of the hybrid vehicle of the second embodiment and the configuration of the four-speed hybrid transmission of the first embodiment, the operating modes of this embodiment have different mode matching methods, and a variety of different operating modes can be set.

[0063] like Figure 2 As shown, from the perspective of pure electric drive and engine drive, the operating modes can be divided into three major categories: pure electric mode, hybrid mode, and engine mode. Among them, the pure electric mode can be further divided into electric rear-wheel drive mode, electric front-wheel drive mode, and electric four-wheel drive mode. The hybrid mode can be further divided into hybrid front-wheel drive mode and hybrid four-wheel drive mode. The engine mode can be further divided into engine direct drive mode, series mode, and idle power generation mode. From the perspective of master-slave drive and four-wheel drive of the front axle wheels 11 and rear axle wheels 12, the operating modes can be divided into two major categories: two-wheel drive mode and four-wheel drive mode. The above-mentioned electric rear-wheel drive mode, electric front-wheel drive mode, hybrid front-wheel drive mode, engine direct drive mode, and series mode are all two-wheel drive modes, while the above-mentioned electric four-wheel drive mode and hybrid four-wheel drive mode are all four-wheel drive modes.

[0064] In addition, for special vehicle operating conditions, the operating modes may also include launch mode and energy recovery mode. The specific configuration of the above operating modes and the status of the relevant power components and transmission components are shown in the table below:

[0065]

[0066] Specifically, in the electric rear-wheel drive mode, the engine 20 does not work, the cut-off mechanism is in the disconnected state, the first motor 21 does not work, the shift mechanism does not transmit power, and the front axle wheels 11 are in a driven state; at the same time, the second motor 22 runs to output power, and the rear axle wheels 12 are driven to drive the vehicle forward.

[0067] In the electric front-wheel drive mode, the engine 20 does not work, the cut-off mechanism is in the disconnected state, the first motor 21 outputs power, the shift mechanism transmits power, the front axle wheels 11 are driven to drive the vehicle forward; at the same time, the second motor 22 does not work, and the rear axle wheels 12 are in a driven state.

[0068] In the electric four-wheel drive mode, the engine 20 does not work, the cut-off mechanism is in the disconnected state, the first motor 21 outputs power, the shift mechanism transmits power, and the front axle wheels 11 are driven; at the same time, the second motor 22 runs to output power, and the rear axle wheels 12 are also driven, so that the vehicle is in a four-wheel drive state.

[0069] In the hybrid front-wheel drive mode, the engine 20 is running, the disconnect mechanism is in the engaged state, the first motor 21 outputs power, the shift mechanism transmits power, and the front axle wheels 11 are driven simultaneously by the engine 20 and the first motor 21 to drive the vehicle forward; at the same time, the second motor 22 is not working, and the rear axle wheels 12 are in a driven state.

[0070] In the hybrid four-wheel drive mode, the engine 20 is running, the disconnection mechanism is in the engaged state, the first motor 21 is not working, the shift mechanism transmits power, and the front axle wheels 11 are driven by the engine 20; at the same time, the second motor 22 is running to output power, and the rear axle wheels 12 are also driven, so that the vehicle is in a four-wheel drive state.

[0071] In the engine direct drive mode, the engine 20 is running, the cut-off mechanism is in the engaged state, the first motor 21 is not working, the shift mechanism transmits power, and the front axle wheels 11 are driven by the engine 20 to drive the vehicle forward; at the same time, the second motor 22 is not working, and the rear axle wheels 12 are in a driven state.

[0072] In series mode, the engine 20 is running, the disconnect mechanism is in the engaged state, the first motor 21 is running to generate electricity, the shift mechanism does not transmit power, and the front axle wheels 11 are in the driven state; at the same time, the second motor 22 is running to output power, and the rear axle wheels 12 are driven to drive the vehicle forward.

[0073] In the idle power generation mode, the engine 20 is running, the cut-off mechanism is in the engaged state, the shift mechanism does not transmit power, the front axle wheels 11 are stationary, and the engine 20 only drives the first motor 21 to operate and generate electricity; at the same time, the second motor 22 is not working, and the rear axle wheels 12 are stationary.

[0074] In launch mode, the engine 20 is running, the cut-off mechanism is in the engaged state, the first motor 21 outputs power, the shift mechanism transmits power, and the front axle wheels 11 are driven simultaneously by the engine 20 and the first motor 21 to drive the vehicle forward; at the same time, the second motor 22 is running to output power, and the rear axle wheels 12 are also driven, so that the vehicle is in a four-wheel drive state.

[0075] In energy recovery mode, the engine 20 is deactivated and the disconnect mechanism is disengaged. The first and second motors 21 and 22 can operate to generate electricity, driven by the front and rear wheels 11 and 12, respectively. Specifically, this mode can be categorized into front axle energy recovery mode, rear axle energy recovery mode, and dual-axle energy recovery mode. When the vehicle is operating in front axle energy recovery mode, the disconnect mechanism disconnects power, the shift mechanism engages the shift gear set, the engine 20 is deactivated, the first motor 21 operates to generate electricity, driven by the front wheels 11, and the second motor 22 is deactivated. When the vehicle is operating in rear axle energy recovery mode, the disconnect mechanism disconnects power, the shift mechanism disengages the shift gear set, and both the engine 20 and the first motor 21 are deactivated. The second motor 22 operates to generate electricity, driven by the rear wheels 12. When the vehicle is operating in dual-axle energy recovery mode, the disconnect mechanism disconnects power, the shift mechanism engages the shift gear set, the engine 20 is deactivated, and the first and second motors 21 and 22 operate to generate electricity, driven by the front and rear wheels 11 and 12, respectively.

[0076] Based on the rich operating mode settings of the above-mentioned vehicles, the vehicle's own GPS module, radar module, camera and other sensor devices can be used to obtain environmental parameters and working parameters such as the speed and distance of the vehicle in front when following the vehicle, so as to establish intelligent safety model data such as the vehicle's overall safety distance; or, working parameters such as motor torque, battery power, accelerator pedal opening, vehicle speed and wheel speed can be read from the on-board control unit to comprehensively judge the current vehicle's suitable operating mode, so as to control the vehicle to operate in the appropriate operating mode.

[0077] Specifically, if Figure 2 As shown, the operating parameters of this embodiment include the battery charge detected by battery 25, the operating modes of the aforementioned pure electric mode, engine mode, and hybrid mode; and the preset conditions include a first charge value and a second charge value, set in descending order. Based on this, pure electric mode is executed when the battery charge value is above the first charge value, engine mode is executed when the battery charge value is below the second charge value, and hybrid mode is executed when the battery charge value is between the first and second charge values. Selecting pure electric mode, hybrid mode, or engine mode based on the current battery charge value of battery 25 effectively avoids battery 25 depletion while fully utilizing the stored energy of battery 25, thus balancing the vehicle's operating economy and reliability and improving the vehicle's fuel economy.

[0078] The above-mentioned first power value and second power value can be flexibly set within a reasonable range. For example, the first power value can refer to 60% of the total battery power. When the battery power is greater than or equal to 60%, it means that the battery power of the entire vehicle is sufficient. Of course, the first power value can also refer to 40%, 50% or 70% of the total battery power, etc., and can be set specifically according to the battery capacity. When the battery capacity is relatively large, the first power value can also be 30% or 20% of the total battery power, etc. When the battery capacity is relatively small, the first power value should be set higher. Similarly, on the premise of ensuring that the second power value is lower than the first power value, it can be 30%, 20% or 10% of the total battery power, and can be flexibly adjusted according to the size of the battery capacity.

[0079] It should be noted that in pure electric mode, the aforementioned electric rear-wheel drive mode, electric front-wheel drive mode, or electric four-wheel drive mode may be used. Preferably, the electric rear-wheel drive mode is used first. Furthermore, the operating parameters also include detecting a motor fault signal obtained by the second motor 22. In the pure electric rear-wheel drive mode, when a motor fault signal is generated, the electric front-wheel drive mode is switched to use.

[0080] In addition, the engine mode of this embodiment includes the above-mentioned engine direct drive mode, series mode and idle power generation mode. The working parameters also include the vehicle speed, and the preset conditions also include the set speed. Based on this, in the engine mode, the engine direct drive mode is executed when the vehicle speed of the moving vehicle is greater than the set speed, and the series mode is executed when it is less than or equal to the set speed (but the speed is not zero). When the vehicle speed is zero and the vehicle is idling, the vehicle executes the idle power generation mode. When the battery 25 has a low remaining battery power, the engine mode is adopted to prevent the battery power from further decreasing. At the same time, the engine direct drive mode, series mode or idle power generation mode is adopted accordingly according to the different conditions of the vehicle operation and the vehicle speed. While ensuring the power required for the vehicle operation, the first motor 21 can be used to convert the redundant power output by the engine 20 into electrical energy to supplement the battery 25, thereby achieving a good battery power replenishment effect.

[0081] As will be appreciated, determining which mode to select when the battery 25 is low on charge based on the vehicle's speed can better match the vehicle's power requirements with the actual battery 25 charge level. In this case, the vehicle's speed is first obtained, and then the selection of series mode or engine direct drive mode is determined by determining whether the vehicle's speed is greater than a set speed. For example, the set speed may be 30 km / h. If the battery charge level is less than or equal to a second charge level, when the vehicle's speed is less than or equal to 30 km / h, the vehicle is controlled to operate in series mode; when the vehicle's speed is greater than 30 km / h, the vehicle is controlled to operate in engine direct drive mode. Of course, the set speed can be set to other values ​​as needed, such as 20 km / h, 40 km / h, or 50 km / h, and is not specifically limited in this embodiment. If the battery charge level is less than or equal to the second charge level, and the vehicle's speed is detected to be zero (idling), the vehicle can be controlled to operate in idle power generation mode. The vehicle controller sends a power generation request signal to the first motor 21, and the engine 20 drives the first motor 21 to generate electricity, thereby charging the battery 25.

[0082] In addition, the working parameters of this embodiment also include the accelerator pedal opening, the vehicle speed and the wheel speed. Figure 2 As shown, when the rate of change of the accelerator pedal opening rises above the set threshold, or the wheel speed does not match the vehicle speed, it is preferred to switch the vehicle from the above-mentioned two-wheel drive mode to the four-wheel drive mode. Specifically, in pure electric mode, the electric rear-wheel drive mode or the electric front-wheel drive mode is switched to the electric four-wheel drive mode; in hybrid mode, the hybrid front-wheel drive mode is switched to the hybrid four-wheel drive mode. Based on the changes in the rate of change of the accelerator pedal opening or the matching of the wheel speed with the vehicle speed, timely switching of the two-wheel drive mode to the four-wheel drive mode is conducive to improving the vehicle's off-road escape capability and enabling the vehicle to adapt to different road conditions; timely switching between the two-wheel drive mode and the four-wheel drive mode not only enables the vehicle to adapt to different complex road conditions and meet the requirements of rapid acceleration, but also maintains good operating economy of the vehicle.

[0083] The above-mentioned accelerator pedal opening can refer to the angle of the accelerator pedal, and the rate of change of the accelerator pedal opening can refer to the speed at which the accelerator pedal is depressed. For example, the accelerator pedal opening can be represented by D, and the set threshold can be 0.1D per millisecond. In the electric rear-wheel drive mode, when the rate of change of the accelerator pedal opening is greater than or equal to 0.1D per millisecond, the vehicle controller sends a front axle drive signal according to the accelerator pedal opening requirement to control the vehicle to switch to the electric four-wheel drive mode; or, in the hybrid front-wheel drive mode, sends a rear axle drive signal to control the vehicle to switch to the hybrid four-wheel drive mode. In this case, the electric four-wheel drive mode or the hybrid four-wheel drive mode can bring stronger power than the two-wheel drive mode, thereby improving the user experience.

[0084] It should be noted that the above-mentioned threshold setting is only an example. The threshold setting can also be other values, such as 0.05D per millisecond, 0.15D per millisecond, 0.2D per millisecond, etc. It can be set specifically according to different situations and is not specifically limited here.

[0085] In addition to switching the four-wheel drive mode based on the aforementioned rate of change of the accelerator pedal opening, electric four-wheel drive mode or hybrid four-wheel drive mode is also preferably engaged when the vehicle speed and wheel speed do not match. The mismatch between the vehicle speed and wheel speed can be determined based on the difference between the wheel speeds being greater than or equal to a set speed difference. When the pre-set mismatch condition is met, the four-wheel drive mode is engaged.

[0086] Generally speaking, the vehicle speed and wheel speed are matched, that is, the wheel speed and the vehicle speed are consistent. If the vehicle speed and wheel speed do not match, it means that the wheels are slipping, such as slipping on snow or potholes. In this case, the vehicle can operate in electric four-wheel drive mode and output high torque to get out of trouble. The "set speed difference" provides a basis for determining whether to select four-wheel drive mode under this operating condition. The wheel speed difference can refer to the speed difference between the front axle wheel 11 and the rear axle wheel 12, or the difference between the left and right wheels of the front axle wheel 11, or the difference between the left and right wheels of the rear axle wheel 12. The set speed difference can be set as needed. For example, the set speed difference can be 10 to 20 revolutions, or 3 to 5 revolutions, etc.

[0087] A preset speed value can also be set. When the vehicle speed exceeds the preset speed value, the vehicle switches to hybrid four-wheel drive mode. When the vehicle speed falls below the preset speed value, the vehicle switches to electric four-wheel drive mode. The preset speed value can be flexibly selected between 15 km / h and 50 km / h, for example, 28 km / h. This setting helps to utilize the engine 20's higher driving efficiency under high-speed driving conditions, further improving the vehicle's operating economy.

[0088] In addition, the control method of this embodiment also provides a strategy for power output torque to improve the economy and safety of vehicle operation; an exemplary control logic is as follows: Figure 3 and Figure 4 shown.

[0089] Specifically, strategies for power output torque include an output torque limitation strategy implemented during the transition from two-wheel drive mode to four-wheel drive mode, and an output torque correction strategy implemented when a vehicle is present within a set distance ahead. The output torque limitation strategy involves determining whether the driven wheels require torque input, and only switching from two-wheel drive to four-wheel drive mode when such a requirement exists. The output torque correction strategy involves obtaining the speed of the preceding vehicle, the vehicle's speed, and the following distance, and presetting a safe following distance; calculating the safe acceleration allowed to maintain the following distance above the safe following distance based on the preceding vehicle's speed, the vehicle's speed, the following distance, and the following safety distance; and correcting the output torque determined based on changes in accelerator pedal opening to keep the actual acceleration obtained from the actual output torque below the safe acceleration.

[0090] As for the output torque correction strategy, there are of course many ways to implement it. In this embodiment, refer to Figure 4 As shown, the following specific control steps can be adopted:

[0091] First, the system determines whether there are any vehicles within a set distance ahead of the vehicle. If so, it obtains the preceding vehicle's speed, the vehicle's own speed, and the following distance. A safe following distance is also pre-set. Based on these speeds, the following distance, and the safe following distance, it calculates the safe acceleration allowed to maintain the following distance above the safe following distance. Simultaneously, it measures the accelerator pedal's position in real time to estimate the acceleration that would result from such a change. If the acceleration exceeds the safe acceleration, the vehicle's output torque is modified to keep the actual acceleration below the safe acceleration.

[0092] It should be noted that there are many methods for calculating the safe acceleration. From the perspective of computational efficiency, the following formula is preferred:

[0093] a0=(L-L0)*K 2 +(v1-v0)*K

[0094] Where: a0 is the safety acceleration, v1 is the speed of the preceding vehicle, v0 is the speed of the own vehicle, K is the coefficient, L is the current following distance, and L0 is the following safety distance.

[0095] Among the above parameters, the current following distance L, which is the distance between the vehicle and the preceding vehicle, and the safe following distance L0 are pre-set values ​​that can be appropriately determined based on traffic regulations, the vehicle's braking performance, and other factors. K is a coefficient related to the time it takes to pursue the preceding vehicle. A smaller K value increases the time it takes to pursue the preceding vehicle; conversely, a larger K value shortens the time it takes to pursue the preceding vehicle. The specific value range of K is related to L, L0, v1, v0, and the vehicle's power, and can be appropriately determined based on the specific conditions of the above parameters.

[0096] The aforementioned speed of the preceding vehicle, the vehicle's own speed, and the following distance can be obtained by calculating the data collected through sensors such as the vehicle's GPS module, radar module, and camera. Alternatively, operating parameters such as the vehicle's own speed and wheel speed can be read from the vehicle's onboard control unit. These can be obtained using existing mature detection methods or technical approaches.

[0097] For a vehicle, given the rated power of its power system, the power output torque corresponding to changes in accelerator pedal opening is essentially fixed. Based on the vehicle's current road conditions, power consumption, and other factors, the actual acceleration generated by changes in accelerator pedal opening can be estimated. Using the safe acceleration as the upper limit, the actual torque the vehicle should output can be calculated in reverse order. Therefore, by correcting the vehicle's output torque, the actual acceleration can be controlled below the safe acceleration. The control range can be appropriately set, for example, the actual acceleration can be controlled to 80% or 90% of the safe acceleration. Preferably, when correcting the vehicle's output torque, the actual output torque is reduced while maintaining the actual acceleration consistent with the safe acceleration. This achieves a relatively ideal dynamic response, maximizing the vehicle's power output performance while ensuring safety.

[0098] Figure 5 The following graph compares the demanded torque (corrected initial output torque) and actual output torque (corrected output torque) corresponding to the accelerator pedal opening, using the aforementioned correction method to correct the vehicle's output torque. Curve A in the figure shows the time curve of the corrected initial output torque, and curve B shows the time curve of the corrected output torque.

[0099] The output torque correction strategy of the control method of this embodiment is aimed at the need for safe driving assistance in the case of following a vehicle. By acquiring data such as the speed of the preceding vehicle, the following distance, and the speed of the own vehicle in real time and setting a reasonable following safety distance threshold, the strategy can accurately calculate the appropriate safe acceleration, control the acceleration of the vehicle below the safe acceleration, and effectively prevent the occurrence of rear-end collisions, thereby providing a good intelligent assistance function for safe driving. The calculation logic of the entire correction strategy is simple, which facilitates the rapid completion of calculation responses, and is conducive to improving the vehicle's safe driving intelligent assistance level.

[0100] As for the output torque limiting strategy, there are also multiple options for implementation. In this embodiment, refer to Figure 3 As shown, the following specific control steps can be adopted:

[0101] The vehicle's accelerator pedal opening and the wheel speeds of the driving and driven wheels are acquired in real time. A torque input demand is considered present when the following two conditions (since switching to four-wheel drive mode is generally required for off-road conditions, the following two conditions are also referred to as off-road preset conditions) are met:

[0102] Off-road preset condition 1: The rate of change of the accelerator pedal opening rises above the set threshold;

[0103] Off-road preset condition two: the difference between the wheel speed of the driving wheel and the wheel speed of the driven wheel is greater than the set speed difference.

[0104] By setting relevant strategies for power output torque in the control method of this embodiment, based on the configuration condition that the active wheels and driven wheels of the vehicle can be driven separately, the two-wheel drive mode is adopted during normal driving, and the four-wheel drive mode is switched to in real time and accurately when sudden acceleration or escape is required; by judging the actual driving torque demand of the driven wheels before switching, the necessity, accuracy and effectiveness of the four-wheel drive mode switching are determined, thereby improving the comprehensive driving efficiency and operating economy of the vehicle; at the same time, for the need for safe driving assistance in the case of following a vehicle, by obtaining data such as the speed of the preceding vehicle, the following distance and the speed of the own vehicle in real time, and setting a reasonable following safety distance threshold, the appropriate safe acceleration can be accurately calculated, and the acceleration of the vehicle can be controlled below the safe acceleration, which can effectively prevent the occurrence of rear-end collisions, thereby providing good intelligent assistance functions for safe driving and helping to improve the safety of vehicle operation.

[0105] In addition, the power system control method of this embodiment also provides a launch control mode and an energy recovery mode. In launch control mode, the engine 20 and the first motor 21 jointly drive the front axle wheels 11, while the second motor 22 drives the rear axle wheels 12. The operating parameters include accelerator pedal opening, and the preset conditions include a set opening value. When the accelerator pedal opening reaches the set opening value, launch control mode is activated. By enabling launch control mode, the engine 20, the first motor 21, and the second motor 22 are fully utilized to drive the vehicle, effectively increasing the vehicle's maximum output power, thereby meeting the rapid acceleration requirements during the vehicle's launch phase and improving the vehicle's launch acceleration performance.

[0106] When the accelerator pedal reaches a set opening value, a launch control command is issued, controlling the vehicle to operate in launch mode. The set opening value can refer to the accelerator pedal being fully depressed, i.e., "floor throttle." At this point, the vehicle controller simultaneously sends drive signals to the engine 20, the first motor 21, and the second motor 22, controlling the vehicle to operate in launch mode. This maximizes vehicle power and provides the driver with a sense of push-back.

[0107] The operating parameters of this embodiment also include a vehicle status signal for determining whether the vehicle is in a braking or coasting state, and the following distance described above. The vehicle executes the energy recovery mode when any of the following preset conditions is met:

[0108] (1) The vehicle is in braking or coasting state;

[0109] (2) The current following distance is within the preset following distance range.

[0110] The preset following distance range described above can be set with reference to the preset following safety distance. Preferably, the preset following safety distance falls within the preset following distance range, or the preset following distance range is set between the preset following safety distance and the minimum safety distance. For example, if the preset following safety distance is 500 meters and the minimum safety distance is 100 meters, the preset following distance range can be set between 500 meters and 100 meters. This allows the energy recovery mode to provide braking effectiveness when the vehicle's power output correction method is ineffective.

[0111] When the vehicle is sliding in neutral or in braking state, any one of the front axle energy recovery mode, rear axle energy recovery mode and dual-axle energy recovery mode can be activated to charge the battery.

[0112] In the braking state, the step of controlling the vehicle to execute the energy recovery mode includes: obtaining the brake pedal opening; if the brake pedal opening is less than or equal to a first set opening value, controlling the vehicle to operate in the rear axle energy recovery mode; if the brake pedal opening is greater than a second set opening value, controlling the vehicle to operate in the dual-axle energy recovery mode. Here, the second set opening value is greater than the first set opening value, and when the brake pedal opening is between the first set opening value and the second set opening value, the front axle energy recovery mode can be executed.

[0113] "The opening of the brake pedal" can refer to the angle of the brake pedal. For example, the opening of the brake pedal can be represented by d, then the "first set opening value" can be 60%d, and the "second set opening value" can be 70%d. If the opening of the brake pedal is less than or equal to 60%d, the vehicle is controlled to operate in the rear axle energy recovery mode, and generate electricity through the second motor 22; if the opening of the brake pedal is greater than 70%d, the vehicle is controlled to operate in the dual-axle energy recovery mode, and generate electricity jointly through the first motor 21 and the second motor 22.

[0114] It should be noted that the first set opening value and the second set opening value can also be equal. The first set opening value and the second set opening value are not limited to the above examples, and can also be other values. For example, the first set opening value is 40%d, 50%d, etc., and the second set opening value is 80%d, 85%d, 90%d. It can be set according to the situation and no specific restrictions are made here.

[0115] While driving, if a vehicle is detected within a set distance range ahead of the vehicle, it is considered to be in an intelligent following scenario. The vehicle's GPS module, radar module, camera, and other sensors can be used to determine the distance between the vehicle ahead and the vehicle in front. Existing adaptive driving technology can maintain a certain safe distance from the vehicle ahead. When the vehicle's current following distance falls within the preset following distance range, energy recovery mode is activated, achieving energy recovery while reducing vehicle speed.

[0116] Furthermore, based on the configuration conditions of a multi-speed transmission, the intensity of energy regeneration can be varied by automatically controlling downshifts. Depending on when the current following distance falls within different range zones within a preset following distance range, the transmission automatically switches between gears to adjust the intensity of energy regeneration accordingly. For example, if a transmission includes first, second, third, and fourth gears, and the preset following distance range includes four range zones of 500m-400m, 400m-300m, 300m-200m, and 200m-100m (with 100m being a safe distance), the aforementioned gears and zones correspond in sequence. When the current following distance falls within different range zones, energy regeneration is performed in different transmission gears, thereby better maximizing the braking effect and efficiency of energy regeneration in the energy regeneration mode.

[0117] In energy recovery mode, if a fault in the second motor 22 is detected, the vehicle is controlled to operate in front-axle energy recovery mode. In other words, rear-axle energy recovery mode and dual-axle energy recovery mode take priority over front-axle energy recovery mode. If a fault in the second motor 40 occurs, rear-axle energy recovery mode and dual-axle energy recovery mode become unavailable. In this case, the vehicle can operate in front-axle energy recovery mode to recover kinetic energy. The energy recovery mode settings take into account potential kinetic energy loss, maximizing energy recovery during braking or coasting.

[0118] In summary, the control method of the power system of this embodiment is based on the configuration of the engine 20, the first motor 21 and the second motor 22. Through the coordinated driving of the three drive components in different operating states, different operating modes such as front-wheel drive, rear-wheel drive, four-wheel drive, pure electric, and hybrid can be configured for the vehicle to cope with different operating conditions and driving requirements of the vehicle; by detecting and acquiring the vehicle's operating parameters in real time, the current appropriate operating mode of the vehicle can be determined, thereby controlling the vehicle to operate in a suitable operating mode, which is conducive to improving the comprehensive driving efficiency of the hybrid vehicle.

[0119] At the same time, the overall control logic of the control method of this embodiment is simple and efficient, avoiding the shortcomings of the existing hybrid vehicle shift control strategy, such as cumbersome, frequent and inefficient mode switching, and has good adaptability and economy.

[0120] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A four-speed hybrid transmission, characterized in that: It comprises an input shaft, a first output shaft (311) and a second output shaft (312) arranged in parallel; A first driving gear (303) and a second driving gear (304) are arranged on the input shaft at intervals; A first gear driven gear (321), a second gear driven gear (322), and a first shift mechanism (421) selectively engaging with the first gear driven gear (321) or the second gear driven gear (322) are mounted on the first output shaft (311); The second output shaft (312) is fitted with a third gear driven gear (323), a fourth gear driven gear (324), and a second shift mechanism (422) that can selectively engage with the third gear driven gear (323) or the fourth gear driven gear (324); The first gear driven gear (321) and the third gear driven gear (323) are both meshed and connected with the first driving gear (303), and the second gear driven gear (322) and the fourth gear driven gear (324) are both meshed and connected with the second driving gear (304); The input shaft comprises a first input shaft (301) and a second input shaft (302) sleeved on the first input shaft (301); the first driving gear (303) is fixedly mounted on the first input shaft (301); and the second driving gear (304) is fixedly mounted on the second input shaft (302); a first clutch (411) for receiving power input is provided at the end of the input shaft; the first clutch (411) can selectively engage the first input shaft (301) or the second input shaft (302); The four-speed hybrid transmission is integrated with a first motor (21) and a third motor (23), wherein the first motor (21) is connected to the input shaft via the first clutch (411); a motor transmission gear set (33) is provided at one end of the first input shaft (301) away from the first clutch (411), and the motor transmission gear set (33) receives power input from the third motor (23).

2. The four-speed hybrid transmission according to claim 1, characterized in that: The first output shaft (311) is provided with a first output gear (325), and the second output shaft (312) is provided with a second output gear (326). The first output gear (325) is meshed and connected with the second output gear (326), and the second output gear (326) is used for power output.

3. A hybrid vehicle comprising an engine (20) and a first motor (21) for driving front axle wheels (11), a second motor (22) for driving rear axle wheels (12), and a battery (25) connected to the first motor (21) and the second motor (22); characterized in that: The hybrid vehicle is equipped with the four-speed hybrid transmission according to claim 1 or 2, and the engine (20) and the first motor (21) both transmit power to the front axle wheels (11) through the four-speed hybrid transmission.

4. A control method for a hybrid vehicle according to claim 3, characterized in that: The control method includes: By matching different operating states of the engine (20), the first motor (21), and the second motor (22), a plurality of operating modes are configured for the vehicle, and a plurality of preset conditions related to the operating parameters of the vehicle are set corresponding to each of the operating modes; The changes of the operating parameters are acquired in real time, and the vehicle is controlled to operate in the operating mode corresponding to the preset conditions that the operating parameters meet.

5. The control method according to claim 4, characterized in that: The operating parameters include a battery charge value obtained by detecting the battery (25), and the operating modes include a pure electric mode in which the vehicle is driven by the first motor (21) and / or the second motor (22), an engine mode in which the engine (20) provides power output, and a hybrid mode in which the vehicle is driven by the engine (20) in cooperation with the first motor (21) or the second motor (22); The preset conditions include a first power value and a second power value set in sequence from high to low. The pure electric mode is executed when the battery power is above the first power value, the engine mode is executed when the battery power is below the second power value, and the hybrid mode is executed when the battery power is between the first power value and the second power value.

6. The control method according to claim 4, characterized in that: The operating mode includes a launch mode, and the operating parameter includes an accelerator pedal opening; In the launch mode, the engine (20) and the first motor (21) jointly drive the front axle wheels (11), and the second motor (22) drives the rear axle wheels (12); The preset condition includes a set opening value, and when the accelerator pedal opening reaches the set opening value, the launch start mode is executed.

7. The control method according to claim 4, characterized in that: The operating mode includes an energy recovery mode in which the first motor (21) is driven by the front axle wheel (11) and / or the second motor (22) is driven by the rear axle wheel (12) to operate and generate electricity, and the operating parameters include a vehicle status signal for determining whether the vehicle is in a braking or coasting state, and a following distance. When any of the following preset conditions is met, the vehicle executes the energy recovery mode: The vehicle is in a braking or coasting state; The following distance falls within a preset following distance range.

8. The control method according to any one of claims 4 to 7, characterized in that: It also includes an output torque limiting strategy executed during the switch from two-wheel drive mode to four-wheel drive mode, and an output torque correction strategy executed when there is a vehicle within a set distance range ahead; The output torque limiting strategy includes: determining whether there is a torque input demand from the driven wheel, and switching from the two-wheel drive mode to the four-wheel drive mode only when the driven wheel has a torque input demand; The output torque correction strategy includes: obtaining the speed of the preceding vehicle, the speed of the host vehicle and the following distance, and presetting a following safety distance; calculating the allowable safe acceleration for maintaining the following distance above the following safety distance based on the speed of the preceding vehicle, the speed of the host vehicle, the following distance and the following safety distance; and correcting the output torque determined based on the change in the accelerator pedal opening to control the actual acceleration obtained by the actual output torque to be below the safe acceleration.

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