Vehicle mode switching method, device and system and vehicle

Abstract

The invention provides a vehicle mode switching method, device and system and a vehicle, and belongs to the technical field of vehicle control. According to the embodiment of the invention, the vehicle is controlled to enter an idling electric four-wheel drive mode when the vehicle is started, and when the vehicle meets the mode switching condition of switching from the idling electric four-wheel drive mode to a power dividing mode, the power dividing mode can be switched from the idling electric four-wheel drive mode to the power dividing mode; the gear shifting operation of the first synchronizer can be achieved by adjusting the torque of the first motor, and the clutch is controlled to be closed by adjusting the rotating speed of the first motor, so that the engine can quickly output the torque after the clutch is closed. According to the embodiment of the invention, the engine is controlled to be in the idling state in advance, so that when the vehicle needs to be switched from the idling electric four-wheel drive mode to the power dividing mode, the clutch can be controlled to be quickly closed after the first synchronizer completes the gear shifting operation, and meanwhile, the engine can immediately output the torque, so that the mode switching time is shortened; and the dynamic response performance of the vehicle in the mode switching process is improved.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle control, and particularly to a vehicle mode switching method, device, system, and vehicle. Background Art

[0002] With the rapid development of the automotive industry, traditional fuel vehicles are gradually moving towards hybrid vehicles. Hybrid vehicles usually have multiple driving modes including a pure electric four-wheel drive mode and a power split mode to adapt to different road conditions and driving requirements. During vehicle driving, the driving modes will switch to each other under certain conditions.

[0003] In the related art, when the vehicle switches from the pure electric four-wheel drive mode to the power split mode, the engine needs to be started. However, it takes a certain amount of time for the engine to start and output power, resulting in problems such as a long mode switching duration and untimely engine power response, which in turn affects the power response performance of the vehicle during mode switching. Summary of the Invention

[0004] The present application provides a vehicle mode switching method, device, system, and vehicle to solve the problems of a long mode switching duration and untimely engine power response when a hybrid vehicle switches from the pure electric four-wheel drive mode to the power split mode.

[0005] To solve the above problems, the present application adopts the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a vehicle mode switching method. The vehicle includes an engine, a clutch, a first motor, and a gearbox; the gearbox includes a power split mechanism, a first synchronizer, and a gearbox input shaft. The engine is connected to a first input end of the power split mechanism through the clutch, the first motor is connected to a second input end of the power split mechanism, an output end of the power split mechanism is connected to the gearbox input shaft, and the first synchronizer is disposed between the first input end and the output end. The method includes:

[0007] When it is detected that the vehicle starts, controlling the vehicle to enter an idle electric four-wheel drive mode; in the idle electric four-wheel drive mode, the engine is in an idle state and the clutch is in an open state;

[0008] When the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode, adjusting the torque of the first motor to make the first synchronizer meet the gear shifting condition;

[0009] When the first synchronizer meets the gear shifting condition, controlling the first synchronizer to switch from the engaged gear to the power split gear;

[0010] When the first synchronizer is in the power split gear position, adjust the speed of the first motor so that the clutch switches from the open state to the closed state;

[0011] When the clutch is in the closed state, control the engine to output torque so that the vehicle switches from the idle electric four-wheel drive mode to the power split mode.

[0012] In an embodiment of the present application, the method further includes:

[0013] When the current remaining power of the power battery is less than the power threshold, determine that the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode.

[0014] In an embodiment of the present application, the step of adjusting the torque of the first motor includes:

[0015] Based on a preset torque adjustment gradient, control the current motor torque of the first motor to follow a preset target motor torque.

[0016] In an embodiment of the present application, the method further includes:

[0017] When the torque difference between the current motor torque and the target motor torque is less than the torque threshold, trigger timing for the duration during which the torque difference is less than the torque threshold;

[0018] When the duration is greater than the duration threshold, determine that the first synchronizer meets the gear shifting condition.

[0019] In an embodiment of the present application, the step of adjusting the speed of the first motor so that the clutch switches from the open state to the closed state includes:

[0020] Based on the current engine speed of the engine, determine the target motor speed of the first motor;

[0021] Control the first motor to follow the target motor speed so that the clutch switches from the open state to the closed state.

[0022] In an embodiment of the present application, the power split mechanism includes a ring gear, a sun gear, a plurality of planet gears meshing between the ring gear and the sun gear, and a planet carrier rotatably connected to the plurality of planet gears; the planet carrier is connected to the engine as the first input end, the sun gear is connected to the first motor as the second input end, the ring gear is connected to the transmission input shaft as the output end, and the first synchronizer is arranged between the planet carrier and the ring gear;

[0023] The step of determining the target motor speed of the first motor based on the current engine speed of the engine includes:

[0024] When the current gear position of the first synchronizer is the power split gear position, determining the speed ratio between the planet carrier and the sun gear as a first speed ratio;

[0025] Based on the current engine speed and the first speed ratio, determining the target motor speed.

[0026] In an embodiment of the present application, the step of controlling the first motor to follow the target motor speed so that the clutch switches from the open state to the closed state includes:

[0027] When the speed difference between the current motor speed of the first motor and the target motor speed is less than a first speed difference threshold, controlling the clutch to switch from the open state to the slip grinding state;

[0028] When the speed difference is less than a second speed difference threshold, controlling the clutch to switch from the slip grinding state to the closed state; wherein, the second speed difference threshold is less than the first speed difference threshold.

[0029] In a second aspect, based on the same inventive concept, an embodiment of the present application provides a vehicle mode switching device. The vehicle includes an engine, a clutch, a first motor, and a transmission; the transmission includes a power split mechanism, a first synchronizer, and a transmission input shaft. The engine is connected to a first input end of the power split mechanism through the clutch, the first motor is connected to a second input end of the power split mechanism, an output end of the power split mechanism is connected to the transmission input shaft, and the first synchronizer is arranged between the first input end and the output end; the device includes:

[0030] A mode control module, configured to control the vehicle to enter an idle electric four-wheel drive mode when it detects that the vehicle starts; in the idle electric four-wheel drive mode, the engine is in an idle state and the clutch is in an open state;

[0031] A torque adjustment module, configured to adjust the torque of the first motor when the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode, so that the first synchronizer meets the gear position switching condition;

[0032] A gear position switching module, configured to control the first synchronizer to switch from the engaged gear position to the power split gear position when the first synchronizer meets the gear position switching condition;

[0033] A rotational speed adjustment module, configured to adjust the rotational speed of the first motor when the first synchronizer is in the power split gear position, so as to switch the clutch from the open state to the closed state;

[0034] A mode switching module, configured to control the engine to output torque when the clutch is in the closed state, so as to switch the vehicle from the idle electric four-wheel drive mode to the power split mode.

[0035] In an embodiment of the present application, the vehicle mode switching device further includes:

[0036] A mode switching condition determination module, configured to determine that the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode when the current remaining power of the power battery is less than the power threshold.

[0037] In an embodiment of the present application, the torque adjustment module includes:

[0038] A motor torque following sub-module, configured to control the current motor torque of the first motor to follow a preset target motor torque based on a preset torque adjustment gradient.

[0039] In an embodiment of the present application, the vehicle mode switching device further includes:

[0040] A duration statistics module, configured to trigger timing of the duration during which the torque difference between the current motor torque and the target motor torque is less than a torque threshold when the torque difference is less than the torque threshold.

[0041] A gear position switching condition determination module, configured to determine that the first synchronizer meets the gear position switching condition when the duration is greater than a duration threshold.

[0042] In an embodiment of the present application, the rotational speed adjustment module includes:

[0043] A motor speed determination sub-module, configured to determine the target motor speed of the first motor based on the current engine speed of the engine;

[0044] A motor speed following sub-module, configured to control the first motor to follow the target motor speed, so as to switch the clutch from the open state to the closed state.

[0045] In an embodiment of the present application, the power splitting mechanism includes a ring gear, a sun gear, a plurality of planet gears meshing between the ring gear and the sun gear, and a planet carrier rotatably connected to the plurality of planet gears; the planet carrier is connected to the engine as the first input end, the sun gear is connected to the first motor as the second input end, the ring gear is connected to the transmission input shaft as the output end, and the first synchronizer is arranged between the planet carrier and the ring gear;

[0046] The motor speed determination sub-module includes:

[0047] A gear ratio determination unit, configured to determine that the gear ratio between the planet carrier and the sun gear is a first gear ratio when the current gear position of the first synchronizer is the power splitting gear position;

[0048] A motor speed determination unit, configured to determine the target motor speed based on the current engine speed and the first gear ratio.

[0049] In an embodiment of the present application, the motor speed following sub-module includes:

[0050] A first control unit, configured to control the clutch to switch from the open state to the slip friction state when the rotational speed difference between the current motor speed of the first motor and the target motor speed is less than a first rotational speed difference threshold;

[0051] A second control unit, configured to control the clutch to switch from the slip friction state to the closed state when the rotational speed difference is less than a second rotational speed difference threshold; wherein, the second rotational speed difference threshold is less than the first rotational speed difference threshold.

[0052] In a third aspect, based on the same inventive concept, an embodiment of the present application provides a vehicle mode switching system. The vehicle includes an engine, a clutch, a first motor, and a transmission; the transmission includes a power splitting mechanism, a first synchronizer, and a transmission input shaft. The engine is connected to the first input end of the power splitting mechanism through the clutch, the first motor is connected to the second input end of the power splitting mechanism, the output end of the power splitting mechanism is connected to the transmission input shaft, and the first synchronizer is arranged between the first input end and the output end; the system includes a vehicle controller, a transmission controller, a motor controller, and an engine controller; wherein,

[0053] The vehicle controller is configured to send a first state holding request to the engine controller and send a second state holding request to the transmission controller when detecting that the vehicle starts;

[0054] The engine controller is configured to control the engine to start and operate at an idle speed in response to the first state holding request; the transmission controller is configured to control the clutch to be in an open state in response to the second state holding request;

[0055] The vehicle controller is further configured to send a motor torque adjustment request to the motor controller when the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode;

[0056] The motor controller is configured to adjust the torque of the first motor in response to the motor torque adjustment request so that the first synchronizer meets the gear shifting condition;

[0057] The vehicle controller is further configured to send a synchronizer shifting request to the transmission controller when the first synchronizer meets the gear shifting condition;

[0058] The transmission controller is configured to control the first synchronizer to switch from the engaged gear to the power split gear in response to the synchronizer shifting request;

[0059] The vehicle controller is further configured to send a motor speed adjustment request to the motor controller when the first synchronizer is in the power split gear;

[0060] The motor controller is further configured to adjust the speed of the first motor in response to the motor speed adjustment request so that the clutch switches from the open state to the closed state;

[0061] The vehicle controller is further configured to send an engine torque output request to the engine controller when the clutch is in the closed state;

[0062] The engine controller is further configured to control the engine to output torque in response to the engine torque output request so that the vehicle switches from the idle electric four-wheel drive mode to the power split mode.

[0063] In a fourth aspect, based on the same inventive concept, an embodiment of the present application provides a vehicle, including the vehicle mode switching system proposed in the third aspect of the present application.

[0064] Compared with the prior art, the present application has the following advantages:

[0065] A vehicle mode switching method provided by an embodiment of the present application can control the vehicle to enter the idle electric four-wheel drive mode when it detects that the vehicle is started. When the vehicle meets the mode switching conditions for switching from the idle electric four-wheel drive mode to the power split mode, the torque of the first motor can be adjusted so that when the first synchronizer meets the gear shifting conditions, the first synchronizer can be controlled to switch from the engaged gear to the power split gear, and the speed of the first motor can be adjusted so that the clutch switches from the open state to the closed state. Furthermore, when the clutch is in the closed state, the engine output torque can be controlled to enable the vehicle to switch from the idle electric four-wheel drive mode to the power split mode. By pre-controlling the engine to be in the idle state, when the vehicle needs to switch from the idle electric four-wheel drive mode to the power split mode, after the first synchronizer completes the gear shifting operation, the clutch can be quickly closed, and at the same time, the engine can immediately output torque, thereby effectively shortening the mode switching duration and achieving faster power response, improving the user's driving experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0067] Figure 1 It is a schematic structural diagram of a hybrid vehicle in an embodiment of the present application.

[0068] Figure 2 It is a flowchart of the steps of a vehicle mode switching method in an embodiment of the present application.

[0069] Figure 3 It is a schematic diagram of the functional modules of a vehicle mode switching device in an embodiment of the present application.

[0070] Figure 4 It is a schematic structural diagram of a vehicle mode switching system in an embodiment of the present application.

[0071] Figure 5 It is a schematic structural diagram of a vehicle in an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0072] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0073] Referring to Figure 1 , a schematic structural diagram of a hybrid vehicle in an embodiment of the present application is shown. The hybrid vehicle is provided with an engine 101, a clutch 102, a first motor 103 and a transmission on the front axle of the vehicle; the transmission includes a power split mechanism 104, a transmission input shaft 107, a transmission output shaft 108, a first synchronizer 105 and a second synchronizer 106. The engine 101 is connected to a first input end of the power split mechanism 104 through the clutch 102, the first motor 103 is connected to a second input end of the power split mechanism 104, and an output end of the power split mechanism 104 is connected to the transmission input shaft 107.

[0074] The first synchronizer 105 is arranged between the first input end and the output end and is used to engage or disengage the first input end and the output end. Specifically, when the first synchronizer 105 is in the engaged gear, the first synchronizer 105 is used to engage the first input end and the output end; when the first synchronizer 105 is in the power split gear, the first synchronizer 105 is used to disengage the first input end and the output end. It should be noted that the first synchronizer 105 is used to control the vehicle to switch between the power split mode and other modes, that is, when the first synchronizer 105 is in the power split gear, the vehicle can be in the power split mode; when the first synchronizer 105 is in the engaged gear, the vehicle can be in other modes except the power split mode, such as the series mode, the direct drive mode or the pure electric four-wheel drive mode, etc.

[0075] The second synchronizer 106 is arranged between the transmission input shaft 107 and the transmission output shaft 108 and is used to engage or disengage the transmission input shaft 107 and the transmission output shaft 108. Specifically, when the second synchronizer 106 is in the engaged gear, the second synchronizer 106 is used to engage the transmission input shaft 107 and the transmission output shaft 108; when the second synchronizer 106 is in the neutral gear, the second synchronizer 106 is used to disengage the transmission input shaft 107 and the transmission output shaft 108.

[0076] Further, the transmission output shaft 108 is also connected to the front axle wheels through a front axle differential 109 and is used to transmit power to the front axle wheels through the front axle differential 109 to drive the front axle of the vehicle; the hybrid vehicle is also provided with a second motor (not shown in the figure) on the rear axle of the vehicle, and the second motor is used to transmit power to the rear axle wheels through a rear axle differential (not shown in the figure) to drive the rear axle of the vehicle.

[0077] Since the hybrid vehicle adopting the above architecture is equipped with a power split mechanism 104, and the power split mechanism 104 is simultaneously connected to the engine 101, the first motor 103 and the transmission input shaft 107, the vehicle can have multiple driving modes including a pure electric four-wheel drive mode and a power split mode. Furthermore, by changing the gear states of the clutch 102, the first synchronizer 105 and the second synchronizer 106, the vehicle can switch between different driving modes. Specifically:

[0078] In the pure electric four-wheel drive mode, the engine 101 is in the off state, the clutch 102 is in the open state, the first synchronizer 105 is in the engaged gear, the second synchronizer 106 is in the in-gear state, and both the first motor 103 and the second motor are in the driving state. At this time, the power battery supplies power to both the first motor 103 and the second motor simultaneously. The driving force output by the first motor 103 will be transmitted to the power split mechanism 104 through the second input end, and the power split mechanism 104 will transmit the driving force through the output end, the transmission input shaft 107, the second synchronizer 106, the transmission output shaft 108 and the front axle differential 109 to the front axle wheels; the driving force output by the second motor will be transmitted to the rear axle wheels through the rear axle differential.

[0079] In the power split mode, the first synchronizer 105 is in the power split gear. At this time, the first synchronizer is in the disengaged gear state, which is used to disconnect the first input end and the output end. The second synchronizer 106 is in the in-gear state, the engine 101 is in the driving state, the clutch 102 is in the closed state, the first motor 103 is in the power generation state, and the second motor is in the driving state. At this time, the driving force output by the engine 101 is transmitted to the power split mechanism 104 through the clutch 102 and the first input end. The power split mechanism 104 will transmit a part of the driving force to the first motor 103 through the second input end to drive the first motor 103 to generate electricity (at this time, the first motor 103 outputs negative torque), and the generated electric energy is supplied to the power battery for charging; the power split mechanism 104 will also transmit another part of the driving force to the transmission input shaft 107 through the output end, and the transmission input shaft 107 will sequentially transmit this part of the driving force to the front axle of the vehicle through the second synchronizer 106, the transmission output shaft 108 and the front axle differential 109 to drive the vehicle to travel. Among them, the distribution ratio of the driving force can be set according to actual needs. That is to say, in the power split mode, a part of the output power of the engine 101 is used to drive the first motor 103 to charge the power battery, and the other part of the output power is used to directly drive the vehicle to travel.

[0080] In the related art, when a vehicle switches from a pure electric four-wheel drive mode to a power split mode, the engine 101 needs to be started, and the clutch 102 can be closed only after the rotational speed of the engine 101 is adjusted and the shifting operation of the first synchronizer 105 is completed. Since there are processes of starting the engine 101 and adjusting the engine rotational speed during the mode switching process, the mode switching link is relatively long, resulting in a relatively long mode switching duration and untimely engine power response, thus affecting the power response performance of the vehicle during the mode switching process.

[0081] Aiming at the problems of relatively long mode switching duration and untimely engine power response when the current hybrid vehicle switches from a pure electric four-wheel drive mode to a power split mode. The present application aims to provide a vehicle mode switching method. When the vehicle starts, the vehicle is controlled to enter an idle electric four-wheel drive mode, so that the engine 101 can be kept in an idle state. Then, when the vehicle needs to switch from the idle electric four-wheel drive mode to the power split mode, after the first synchronizer 105 completes the shifting operation, the clutch 102 can be quickly closed, and at the same time, the engine 101 can immediately output torque, thereby effectively shortening the mode switching duration and achieving a faster power response, improving the driving experience of users.

[0082] Refer to Figure 2 , which shows a vehicle mode switching method of the present application, applied to a hybrid vehicle adopting the above architecture. The method may include the following steps:

[0083] S201: When it is detected that the vehicle starts, control the vehicle to enter the idle electric four-wheel drive mode.

[0084] It should be noted that the execution subject of this embodiment may be a computing service device with data processing, network communication, and program running functions, or an electronic device with the above functions such as a driving computer, an in-vehicle computer, etc., such as an ECU (Electronic Control Unit), an HCU (Hybrid Control Unit). This embodiment will take the HCU as the execution subject for illustration. It should be noted that this embodiment does not make a specific limitation on the execution subject of the vehicle.

[0085] It should be noted that in the idle electric four-wheel drive mode, the first synchronizer 105 is in the engaged gear, the second synchronizer 106 is in the in-gear state, the first motor 103 and the second motor are both in the driving state, the engine 101 is in the idle state, and the clutch 102 is in the open state. In this mode, the vehicle is driven forward by the first motor 103 and the second motor, and the engine 101 is in the starting state but does not output torque.

[0086] In this embodiment, since the engine 101 is controlled to be in the idle state when the vehicle starts, whether the vehicle is in the starting stage or in the driving state, if it is detected that the driver has a strong power demand, the engine 101 can quickly respond and output torque, thereby effectively improving the starting performance and power response performance of the vehicle.

[0087] In this embodiment, the vehicle can enter the pre-configured idle electric four-wheel drive mode in various ways. Exemplarily, after the vehicle starts, the driver can, according to his driving needs, send an operation instruction to enter the idle electric four-wheel drive mode to the HCU by directly issuing a voice command, or triggering a pre-configured physical button, or triggering a virtual button on the display screen. The HCU then responds to this operation instruction and controls the vehicle to enter the idle electric four-wheel drive mode; the driver can also, according to his driving needs, set the idle electric four-wheel drive mode as the default mode after the vehicle starts. At this time, when the HCU detects that the vehicle has started, it will automatically control the vehicle to enter the idle electric four-wheel drive mode to meet the driver's power demand in the starting stage.

[0088] In a specific implementation, after the HCU detects that the vehicle has started, it will send a first state holding request to the engine controller, so that the engine controller responds to the first state holding request and controls the engine 101 to start and be in the idle state; at the same time, the HCU will also send a second state holding request to the transmission controller, so that the transmission controller responds to the second state holding request and controls the clutch 102 to be in the open state.

[0089] S202: When the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode, adjust the torque of the first motor 103 so that the first synchronizer 105 meets the gear shifting condition.

[0090] In this embodiment, since in the idle electric four-wheel drive mode, the power source of the vehicle is from the power battery, therefore, as the vehicle travels, the remaining power of the power battery will continuously decrease. To avoid power shortage of the power battery, when the HCU detects that the current remaining power of the power battery is less than the power threshold, it will automatically control the vehicle to switch from the idle electric four-wheel drive mode to the power split mode.

[0091] In this embodiment, considering that when the clutch 102 is open, the engine 101 cannot output torque to the power split mechanism 104, therefore, by adjusting the torque of the first motor 103, the torque that the first motor 103 acts on the first synchronizer 105 through the power split mechanism 104 can be indirectly adjusted, and then the torque at the first synchronizer 105 can be reduced to the torque required for closing.

[0092] In a specific implementation, after the HCU detects that the vehicle meets the mode switching condition, it will send a motor torque adjustment request to the motor controller, so that the motor controller responds to the motor torque adjustment request and adjusts the torque of the first motor 103 to make the first synchronizer 105 meet the gear shifting condition.

[0093] S203: When the first synchronizer 105 meets the gear shifting condition, control the first synchronizer 105 to switch from the engaged gear to the power split gear.

[0094] In this embodiment, after the HCU detects that the first synchronizer 105 meets the gear shifting condition and the current gear is the engaged gear, it will send a first gear shifting instruction indicating that the target gear is the power split gear to the transmission controller, so that the transmission controller responds to the gear shifting instruction and controls the first synchronizer 105 to disengage the gear to the power split gear.

[0095] S204: When the first synchronizer 105 is in the power split gear, adjust the speed of the first motor 103 to make the clutch 102 switch from the open state to the closed state.

[0096] In this embodiment, if the HCU detects that the first synchronizer 105 has been switched to the power split gear, it will trigger the speed adjustment of the first motor 103 and send a speed adjustment request including the target motor speed to the motor controller, so that the motor controller responds to the speed adjustment request and adjusts the current motor speed of the first motor 103 based on the target motor speed, so that the clutch 102 meets the closing condition. It should be noted that for the clutch 102 to close, it is necessary to control the speed difference at both ends of it to be less than a pre-calibrated closing threshold, and this closing threshold needs to be a small value, ideally zero.

[0097] In this embodiment, since the clutch 102 is arranged between the engine 101 and the power split mechanism 104 and the engine 101 is in a stable idle running state, therefore, by adjusting the speed of the first motor 103, the speed on the power split mechanism 104 side can be adjusted, and further the speeds at both ends of the clutch 102 can be adjusted, so that the clutch 102 can switch from the open state to the closed state.

[0098] S205: When the clutch 102 is in the closed state, control the engine 101 to output torque to make the vehicle switch from the idle electric four-wheel drive mode to the power split mode.

[0099] In this embodiment, after the HCU detects that the clutch 102 is completely closed, it will set the current driving mode of the vehicle from the idle electric four-wheel drive mode to the power split mode, and then control the engine 101, the first motor 103 and the second motor to output torque according to the torque distribution strategy in the power split mode.

[0100] Specifically, the torque distribution strategy includes a front axle torque distribution strategy and a rear axle torque output strategy. Among them, the HCU is used to execute the front axle torque distribution strategy, control the engine 101 to output a first torque with a positive value, and control the first motor 103 to output a second torque with a negative value, so as to charge the power battery while driving the front axle of the vehicle. At the same time, the HCU is also used to execute the rear axle torque output strategy, control the second motor to output a third torque with a positive value, so as to drive the rear axle of the vehicle.

[0101] It should be noted that the absolute value of the second torque. In this way, the first torque transmitted from the engine 101 to the power splitting mechanism 104 can be divided by the power splitting mechanism 104 into a generator sub-torque and a driving sub-torque. Among them, the generator sub-torque is equal to the absolute value of the second torque, and is used to be transmitted to the first motor 103 through the power splitting mechanism 104 to drive the first motor 103 to generate electricity, and the generated electric energy is provided to charge the power battery; the driving sub-torque is the difference between the first torque and the absolute value of the second torque, and is used to be transmitted to the transmission input shaft 107 through the power splitting mechanism 104, and then the transmission input shaft 107 is sequentially transmitted to the front axle of the vehicle through the second synchronizer 106, the transmission output shaft 108 and the front axle differential 109 to drive the vehicle to travel.

[0102] In the embodiment of the present application, when the vehicle is started, the vehicle is controlled to enter the idle electric four-wheel drive mode, so that the engine 101 can maintain an idle state. Furthermore, when the vehicle needs to switch from the idle electric four-wheel drive mode to the power splitting mode, after the first synchronizer 105 completes the shifting operation, the clutch 102 can be controlled to close quickly, and at the same time, the engine 101 can immediately output torque, thereby effectively shortening the mode switching duration and achieving faster power response, improving the driving experience of users.

[0103] In a feasible implementation manner, the step of adjusting the torque of the first motor 103 in S202 may specifically include the following sub-steps:

[0104] S202-1: Based on a preset torque adjustment gradient, control the current motor torque of the first motor 103 to follow a preset target motor torque.

[0105] In a specific implementation, the current motor torque of the first motor 103 can be controlled to gradually decrease to the target motor torque according to a preset torque adjustment gradient. Among them, the torque adjustment gradient represents the change amount of torque per unit time. For example, it can be set to 100 N·m / s.

[0106] In this embodiment, by gradually reducing the current motor torque of the first motor 103 according to the torque adjustment gradient, while achieving the adjustment of the motor torque, it can effectively avoid the excessive torque change from affecting the driving smoothness of the vehicle.

[0107] It should be noted that the target motor torque represents the torque at which the first synchronizer 105 can achieve gear shifting. Specifically, the target motor torque can be set according to the actual gear shifting requirements. For example, to increase the service life of the first synchronizer 105, the target motor torque can be set to zero; or to maximize the gear shifting speed, the target motor torque can be set to the maximum torque at which gear disengagement can be achieved; or the target motor torque can be set to a torque between zero and the maximum torque, thereby ensuring the service life of the first synchronizer 105 to a certain extent while increasing the gear shifting speed.

[0108] In a feasible embodiment, the vehicle mode switching method may further include the following steps:

[0109] S301: When the torque difference between the current motor torque and the target motor torque is less than the torque threshold, trigger the timing of the duration during which the torque difference is less than the torque threshold.

[0110] In this embodiment, considering that during the process of adjusting the torque of the first motor 103, torque fluctuations may occur in the first motor 103. Therefore, to ensure the smooth gear shifting operation of the first synchronizer 105, the torque fluctuation condition of the first motor 103 will be detected to determine whether the first motor 103 is in a stable operating state at the same time.

[0111] In a specific implementation, when the HCU first detects that the torque difference between the current motor torque and the target motor torque is less than the torque threshold, it will trigger the timing of the duration. Wherein, the duration represents the duration during which the first motor 103 operates continuously and stably.

[0112] It should be noted that the torque threshold can be set according to the torque control accuracy of the first motor 103. The more accurate the torque control accuracy, the smaller the torque threshold can be set. For example, the torque threshold can be set to 3 N·m.

[0113] S302: When the duration is greater than the duration threshold, determine that the first synchronizer 105 meets the gear shifting condition.

[0114] In this embodiment, when the duration is greater than the duration threshold, it indicates that the current motor torque of the first motor 103 fluctuates within a small range near the target motor torque, that is, it is in a stable operating state. Wherein, the duration threshold can be set to 50 ms.

[0115] In this embodiment, during the process of adjusting the torque of the first motor 103, the current motor torque is monitored simultaneously, so as to accurately determine whether the first synchronizer 105 meets the gear shifting condition, thereby ensuring that the first synchronizer 105 can shift gears smoothly and effectively avoiding situations such as damage to the first synchronizer 105 and gear shifting failure.

[0116] In a feasible embodiment, the step of adjusting the rotational speed of the first motor 103 in S204 to switch the clutch 102 from the open state to the closed state may specifically include the following sub-steps:

[0117] S204-1: Determine the target motor rotational speed of the first motor 103 based on the current engine rotational speed of the engine 101.

[0118] In this embodiment, considering that the rotational speed control accuracy of the engine 101 is limited and rotational speed fluctuations may occur, therefore, to ensure that the rotational speed difference between both ends of the clutch 102 can always be maintained in a state less than the closing threshold during the closing process of the clutch 102, the HCU will control the current engine rotational speed of the engine 101 to remain unchanged, and based on the current engine rotational speed of the engine 101, calculate the target motor rotational speed of the first motor 103 in real time, and control the first motor 103 to follow the target motor rotational speed, so that the clutch 102 can successfully complete the closing operation.

[0119] In this embodiment, since a power split mechanism 104 is provided between the first motor 103 and the engine 101, and different gear states of the first synchronizer 105 affect the speed ratio between the first motor 103 and the engine 101, therefore, to accurately calculate the target motor rotational speed of the first motor 103, the HCU will comprehensively consider the current engine rotational speed of the engine 101 and the current gear position of the first synchronizer 105 to determine the target motor rotational speed of the first motor 103.

[0120] Continue to refer to Figure 1 , the power split mechanism 104 may specifically include a ring gear 1041, a sun gear 1042, a plurality of planet gears 1043 meshing between the ring gear 1041 and the sun gear 1042, and a planet carrier 1044 rotatably connected to the plurality of planet gears 1043; the planet carrier 1044 is connected to the engine 101 as the first input end of the power split mechanism 104, the sun gear 1042 is connected to the first motor 103 as the second input end of the power split mechanism 104, the ring gear 1041 is connected to the transmission input shaft 107 as the output end of the power split mechanism 104, and the first synchronizer 105 is arranged between the planet carrier 1044 and the ring gear 1041.

[0121] In the idle speed electric four-wheel drive mode, the first synchronizer 105 is in the engaged gear. At this time, the planet carrier 1044 and the ring gear 1041 are in the locked state, and the clutch 102 is in the open state. The driving force of the engine 101 cannot be transmitted to the planet carrier 1044 through the clutch 102. The driving force output by the first motor 103 is sequentially transmitted to the front axle of the vehicle through the sun gear 1042, multiple planet gears 1043, ring gear 1041, transmission input shaft 107, second synchronizer 106, transmission output shaft 108, and front axle differential 109 to drive the vehicle to travel.

[0122] In the power split mode, the first synchronizer 105 is in the power split gear. At this time, the planet carrier 1044 and the ring gear 1041 are in the disengaged state, and the clutch 102 is in the closed state. The driving force output by the engine 101 is transmitted to the planet carrier 1044 through the clutch 102. The planet carrier 1044 will transmit a part of the driving force to the first motor 103 through multiple planet gears 1043 and the sun gear 1042 in sequence to drive the first motor 103 to charge the power battery. The first motor 103 is in the power generation state at this time. At the same time, since the second synchronizer 106 is in the in-gear state, the planet carrier 1044 will transmit another part of the driving force to the front axle of the vehicle through multiple planet gears 1043, ring gear 1041, transmission input shaft 107, second synchronizer 106, transmission output shaft 108, and front axle differential 109 in sequence to drive the vehicle to travel.

[0123] Based on the above structure, S204-1 can specifically include the following sub-steps:

[0124] S204-1-1: When the current gear of the first synchronizer 105 is the power split gear, determine that the transmission ratio between the planet carrier 1044 and the sun gear 1042 is the first transmission ratio.

[0125] In this embodiment, considering that the transmission ratio between the planet carrier 1044 and the ring gear 1041 is different when the first synchronizer 105 is in different gears. Among them, when the current gear of the first synchronizer 105 is the power split gear, the transmission ratio between the planet carrier 1044 and the ring gear 1041 is the second transmission ratio. Furthermore, by combining the third transmission ratio between the ring gear 1041 and the sun gear 1042, the transmission ratio between the planet carrier 1044 and the sun gear 1042 can be calculated as the first transmission ratio.

[0126] S204-1-2: Based on the current engine speed and the first transmission ratio, determine the target motor speed.

[0127] In this embodiment, after the HCU calculates the first transmission ratio, it can combine the current engine speed of the engine 101 to determine the target motor speed that the first motor 103 needs to reach currently.

[0128] S204-3: Control the first motor 103 to follow the target motor speed, so that the clutch 102 switches from the open state to the closed state.

[0129] In specific implementation, while the HCU sends a speed control request including the target motor speed to the motor controller, it also sends a speed control flag bit to the motor controller, so that the motor controller controls the first motor 103 to switch from the torque control mode to the speed control mode, to achieve precise control of the speed of the first motor 103.

[0130] In this embodiment, after the motor controller receives the speed control request and switches to the speed control mode, it will activate the PI (proportional-integral) speed loop for the first motor 103, so as to control the current motor speed of the first motor 103 to follow the target motor speed in a closed-loop control manner.

[0131] In specific implementation, a preset PI adjustment strategy can be used to achieve closed-loop control of the motor speed. Specifically, the motor controller is built-in with a proportional controller and an integral controller. The motor controller will first calculate the speed difference between the target motor speed and the current motor speed, and then input the current motor speed and the speed difference into the proportional controller, and a proportional adjustment value can be output; input the current motor speed and the speed difference into the integral controller, and an integral adjustment value can be output; and then based on the proportional adjustment value and the integral adjustment value, adjust the speed of the first motor 103.

[0132] In this embodiment, by comprehensively considering the current gear position of the first synchronizer 105 and the transmission ratio between the first motor 103 and the engine 101, the accurate calculation of the target motor speed can be achieved. At the same time, through closed-loop control of the motor speed, the rapid and precise control of the current motor speed can be realized, and then the speed difference at both ends of the clutch 102 can be effectively balanced, ensuring that the clutch 102 can be smoothly closed.

[0133] In specific implementation, to achieve the rapid closing of the clutch 102, S204-2 may specifically include the following sub-steps:

[0134] S204-2-1: When the speed difference between the current motor speed and the target motor speed of the first motor 103 is less than the first speed difference threshold, control the clutch 102 to switch from the open state to the slip grinding state.

[0135] In this embodiment, during the process of torque adjustment of the first motor 103, the current motor speed will continuously approach the target motor speed. If the HCU detects that the speed difference between the current motor speed and the target motor speed is less than the first speed difference threshold, it will send a speed deactivation request to the motor controller, so that the motor controller responds to this speed deactivation request and exits the PI speed loop for the first motor 103. At the same time, the HCU will also send a pre-fill oil instruction to the transmission controller, so that the transmission controller responds to the pre-fill oil instruction and controls the clutch 102 to perform a pre-fill oil operation. After the pre-fill oil of the clutch 102 is completed, the torque of the clutch 102 is increased, so that the clutch 102 switches from the open state to the slip friction state.

[0136] S204-2-2: When the speed difference is less than the second speed difference threshold, control the clutch 102 to switch from the slip friction state to the closed state.

[0137] In this embodiment, although the motor controller exits the PI speed loop for the first motor 103, due to inertia, the current motor speed will still continue to approach the target motor speed. If the HCU detects that the speed difference between the current motor speed and the target motor speed is less than the second speed difference threshold, it will send a closing instruction to the transmission controller, so that the transmission controller responds to the closing instruction and controls the clutch 102 to perform a closing operation to switch from the slip friction state to the closed state. Among them, the second speed difference threshold is less than the first speed difference threshold.

[0138] In one example, the first speed difference threshold is set to 100 rpm, and the second speed difference threshold is set to 50 rpm. When the HCU detects that the speed difference between the current motor speed and the target motor speed is less than 100 rpm, it will exit the speed control for the first motor 103 and control the clutch 102 to enter the torque control state, and then control the clutch 102 to be in the slip friction state in advance. In this way, when the first motor 103 further reduces the speed difference to less than 50 rpm under the action of inertia, the clutch 102 can complete the closing in a very short time.

[0139] In this embodiment, after the HCU detects that the clutch 102 is completely closed, it will set the current driving mode of the vehicle from the idle electric four-wheel drive mode to the power split mode, and then control the engine 101, the first motor 103 and the second motor to output torque according to the torque distribution strategy in the power split mode.

[0140] In this embodiment, by controlling the clutch 102 to be in the slip friction state in advance, the closing speed of the clutch 102 can be effectively increased, and further the mode switching duration can be shortened.

[0141] In the embodiment of the present application, when the vehicle is started, the engine 101 is controlled to maintain an idle state, which can improve the power response speed of the engine 101 while effectively avoiding torque fluctuations and vehicle jerks caused by starting the engine 101 during the mode switching process. In this way, it is possible to switch from the idle electric four-wheel drive mode to the power split mode more quickly and smoothly. While meeting the charging requirements of the power battery, it is also possible to optimize the operating point of the engine 101 while ensuring that the vehicle still has four-wheel drive capabilities, improve the fuel efficiency of the engine 101, and make the overall vehicle comprehensive energy consumption optimal.

[0142] In a second aspect, based on the same inventive concept, referring to Figure 3 , the embodiment of the present application provides a vehicle mode switching device 300, which is applied to a vehicle. The vehicle includes an engine 101, a clutch 102, a first motor 103, and a gearbox; the gearbox includes a power split mechanism 104, a first synchronizer 105, and a gearbox input shaft 107. The engine 101 is connected to the first input end of the power split mechanism 104 through the clutch 102, the first motor 103 is connected to the second input end of the power split mechanism 104, the output end of the power split mechanism 104 is connected to the gearbox input shaft 107, and the first synchronizer 105 is arranged between the first input end and the output end; the vehicle mode switching device 300 includes:

[0143] A mode control module 301, configured to control the vehicle to enter the idle electric four-wheel drive mode when it detects that the vehicle is started; in the idle electric four-wheel drive mode, the engine 101 is in an idle state and the clutch 102 is in an open state;

[0144] A torque adjustment module 302, configured to adjust the torque of the first motor 103 when the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode, so that the first synchronizer 105 meets the gear shifting condition;

[0145] A gear shifting module 303, configured to control the first synchronizer 105 to switch from the engaged gear to the power split gear when the first synchronizer 105 meets the gear shifting condition;

[0146] A speed adjustment module 304, configured to adjust the speed of the first motor 103 when the first synchronizer 105 is in the power split gear, so that the clutch 102 switches from the open state to the closed state;

[0147] A mode switching module 305, configured to control the engine 101 to output torque when the clutch 102 is in the closed state, so that the vehicle switches from the idle electric four-wheel drive mode to the power split mode.

[0148] In an embodiment of the present application, the vehicle mode switching device 300 further includes:

[0149] A mode switching condition determination module, configured to determine that the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode when the current remaining power of the power battery is less than the power threshold.

[0150] In an embodiment of the present application, the torque adjustment module 302 includes:

[0151] A motor torque following sub-module, configured to control the current motor torque of the first motor 103 to follow a preset target motor torque based on a preset torque adjustment gradient.

[0152] In an embodiment of the present application, the vehicle mode switching device 300 further includes:

[0153] A duration statistics module, configured to trigger timing of the duration during which the torque difference between the current motor torque and the target motor torque is less than the torque threshold when the torque difference is less than the torque threshold;

[0154] A gear shift condition determination module, configured to determine that the first synchronizer 105 meets the gear shift condition when the duration is greater than the duration threshold.

[0155] In an embodiment of the present application, the speed adjustment module 304 includes:

[0156] A motor speed determination sub-module, configured to determine the target motor speed of the first motor 103 based on the current engine speed of the engine 101;

[0157] A motor speed following sub-module, configured to control the first motor 103 to follow the target motor speed so that the clutch 102 switches from the open state to the closed state.

[0158] In an embodiment of the present application, the power split mechanism 104 includes a ring gear 1041, a sun gear 1042, a plurality of planet gears 1043 meshing between the ring gear 1041 and the sun gear 1042, and a planet carrier 1044 rotatably connected to the plurality of planet gears 1043; the planet carrier 1044 is connected to the engine 101 as the first input end of the power split mechanism 104, the sun gear 1042 is connected to the first motor 103 as the second input end of the power split mechanism 104, the ring gear 1041 is connected to the transmission input shaft 107 as the output end of the power split mechanism 104, and the first synchronizer 105 is arranged between the planet carrier 1044 and the ring gear 1041;

[0159] The motor speed determination sub-module includes:

[0160] A variable speed ratio determination unit, configured to determine that the speed ratio between the planet carrier 1044 and the sun gear 1042 is a first speed ratio when the current gear of the first synchronizer 105 is a power split gear;

[0161] An electric motor speed determination unit, configured to determine a target electric motor speed based on the current engine speed and the first speed ratio.

[0162] In an embodiment of the present application, the electric motor speed following sub-module includes:

[0163] A first control unit, configured to control the clutch 102 to switch from an open state to a slip state when the speed difference between the current electric motor speed of the first electric motor 103 and the target electric motor speed is less than a first speed difference threshold;

[0164] A second control unit, configured to control the clutch 102 to switch from a slip state to a closed state when the speed difference is less than a second speed difference threshold; wherein, the second speed difference threshold is less than the first speed difference threshold.

[0165] It should be noted that for the specific implementation manner of the vehicle mode switching device 300 in the embodiment of the present application, refer to the specific implementation manner of the vehicle mode switching method proposed in the first aspect of the embodiment of the present application, which will not be elaborated here.

[0166] In a third aspect, based on the same inventive concept, refer to Figure 4 , the embodiment of the present application provides a vehicle mode switching system 400, which is applied to a vehicle. The vehicle includes an engine 101, a clutch 102, a first electric motor 103, and a gearbox; the gearbox includes a power split mechanism 104, a first synchronizer 105, and a gearbox input shaft 107. The engine 101 is connected to the first input end of the power split mechanism 104 through the clutch 102, the first electric motor 103 is connected to the second input end of the power split mechanism 104, the output end of the power split mechanism 104 is connected to the gearbox input shaft 107, and the first synchronizer 105 is arranged between the first input end and the output end; the vehicle mode switching system 400 includes a vehicle controller 401, a gearbox controller 402, an electric motor controller 403, and an engine controller 404.

[0167] The vehicle controller 401 is configured to send a first state holding request to the engine controller 404 and send a second state holding request to the gearbox controller 402 when detecting that the vehicle starts;

[0168] The engine controller 404 is configured to control the engine 101 to start and be in an idle state in response to the first state holding request; the gearbox controller 402 is configured to control the clutch 102 to be in an open state in response to the second state holding request;

[0169] The vehicle controller 401 is further configured to send a motor torque regulation request to the motor controller 403 when the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode;

[0170] The motor controller 403 is configured to respond to the motor torque regulation request and regulate the torque of the first motor 103 so that the first synchronizer 105 meets the gear shifting condition;

[0171] The vehicle controller 401 is further configured to send a synchronizer shifting request to the transmission controller 402 when the first synchronizer 105 meets the gear shifting condition;

[0172] The transmission controller 402 is configured to respond to the synchronizer shifting request and control the first synchronizer 105 to switch from the engaged gear to the power split gear;

[0173] The vehicle controller 401 is further configured to send a motor speed regulation request to the motor controller 403 when the first synchronizer 105 is in the power split gear;

[0174] The motor controller 403 is further configured to respond to the motor speed regulation request and regulate the speed of the first motor 103 so that the clutch 102 switches from the open state to the closed state;

[0175] The vehicle controller 401 is further configured to send an engine torque output request to the engine controller 404 when the clutch 102 is in the closed state;

[0176] The engine controller 404 is further configured to respond to the engine torque output request and control the engine 101 to output torque so that the vehicle switches from the idle electric four-wheel drive mode to the power split mode.

[0177] It should be noted that the specific implementation of the vehicle mode switching system 400 in the embodiments of the present application refers to the specific implementation of the vehicle mode switching method proposed in the first aspect of the present application, which will not be elaborated here.

[0178] Fourthly, based on the same inventive concept, referring to Figure 5 , the embodiments of the present application provide a vehicle 500, including the vehicle mode switching system 400 proposed in the third aspect of the present application.

[0179] It should be noted that the specific implementation of the vehicle 500 in the embodiments of the present application refers to the specific implementation of the vehicle mode switching system 400 proposed in the third aspect of the present application, which will not be elaborated here.

[0180] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, devices, or computer program products. Therefore, the embodiments of the present invention can take the form of all-hardware embodiments, all-software embodiments, or embodiments combining software and hardware aspects. Moreover, the embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0181] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing terminal devices generate a device for implementing the functions specified in Figure 1 one or more of the flows Figure 1 or a plurality of flows and / or blocks

[0182] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device that implements the functions specified in Figure 1 one or more of the flows Figure 1 or a plurality of flows and / or blocks

[0183] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, such that a series of operation steps are performed on the computer or other programmable terminal device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable terminal device provide steps for implementing the functions specified in Figure 1 one or more of the flows Figure 1 or a plurality of flows and / or blocks

[0184] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0185] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising the element.

[0186] The above has introduced in detail a vehicle mode switching method, device, system and vehicle provided by the present invention. Specific examples are used in this text to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A vehicle mode switching method, characterized in that, The vehicle includes an engine, a clutch, a first motor, and a transmission; the transmission includes a power split mechanism, a first synchronizer, and a transmission input shaft. The engine is connected to a first input end of the power split mechanism through the clutch, the first motor is connected to a second input end of the power split mechanism, an output end of the power split mechanism is connected to the transmission input shaft, and the first synchronizer is arranged between the first input end and the output end; the method includes: When it is detected that the vehicle starts, controlling the vehicle to enter an idle electric four-wheel drive mode; in the idle electric four-wheel drive mode, the engine is in an idle state and the clutch is in an open state; When the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode, adjusting the torque of the first motor so that the first synchronizer meets the gear shifting condition; When the first synchronizer meets the gear shifting condition, controlling the first synchronizer to switch from the engaged gear to the power split gear; When the first synchronizer is in the power split gear, adjusting the speed of the first motor so that the clutch switches from the open state to the closed state; When the clutch is in the closed state, controlling the engine to output torque so that the vehicle switches from the idle electric four-wheel drive mode to the power split mode.

2. The vehicle mode switching method according to claim 1, wherein, The method further includes: When the current remaining power of the power battery is less than the power threshold, determining that the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode.

3. The vehicle mode switching method according to claim 1, wherein, The step of adjusting the torque of the first motor includes: Based on a preset torque adjustment gradient, controlling the current motor torque of the first motor to follow a preset target motor torque.

4. The vehicle mode switching method according to claim 3, wherein The method further includes: When the torque difference between the current motor torque and the target motor torque is less than a torque threshold, triggering timing for the duration during which the torque difference is less than the torque threshold; When the duration is greater than a duration threshold, determining that the first synchronizer meets the gear shifting condition.

5. The vehicle mode switching method according to claim 1, characterized in that, The step of adjusting the speed of the first motor so that the clutch switches from the open state to the closed state includes: Based on the current engine speed of the engine, determining the target motor speed of the first motor; Controlling the first motor to follow the target motor speed so that the clutch switches from the open state to the closed state.

6. The vehicle mode switching method according to claim 5, wherein, The power split mechanism includes a ring gear, a sun gear, a plurality of planet gears meshing between the ring gear and the sun gear, and a planet carrier rotatably connected to the plurality of planet gears; the planet carrier is connected to the engine as the first input end, the sun gear is connected to the first motor as the second input end, the ring gear is connected to the transmission input shaft as the output end, and the first synchronizer is arranged between the planet carrier and the ring gear; The step of determining the target motor speed of the first motor based on the current engine speed of the engine includes: When the current gear position of the first synchronizer is the power split gear position, determine that the speed ratio between the planet carrier and the sun gear is the first speed ratio; Based on the current engine speed and the first speed ratio, determine the target motor speed.

7. The vehicle mode switching method according to claim 5, characterized in that, The step of controlling the first motor to follow the target motor speed so that the clutch switches from the open state to the closed state includes: When the speed difference between the current motor speed of the first motor and the target motor speed is less than the first speed difference threshold, control the clutch to switch from the open state to the slip grinding state; When the speed difference is less than the second speed difference threshold, control the clutch to switch from the slip grinding state to the closed state; wherein, the second speed difference threshold is less than the first speed difference threshold.

8. A vehicle mode switching device, characterized in that, The vehicle includes an engine, a clutch, a first motor, and a transmission; the transmission includes a power split mechanism, a first synchronizer, and a transmission input shaft. The engine is connected to the first input end of the power split mechanism through the clutch, the first motor is connected to the second input end of the power split mechanism, the output end of the power split mechanism is connected to the transmission input shaft, and the first synchronizer is arranged between the first input end and the output end; the device includes: A mode control module, configured to control the vehicle to enter the idle electric four-wheel drive mode when it detects that the vehicle starts; in the idle electric four-wheel drive mode, the engine is in the idle state and the clutch is in the open state; A torque adjustment module, configured to adjust the torque of the first motor when the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode, so that the first synchronizer meets the gear position switching condition; A gear position switching module, configured to control the first synchronizer to switch from the engaged gear position to the power split gear position when the first synchronizer meets the gear position switching condition; A speed adjustment module, configured to adjust the speed of the first motor when the first synchronizer is in the power split gear position, so that the clutch switches from the open state to the closed state; A mode switching module, configured to control the engine to output torque when the clutch is in the closed state, so that the vehicle switches from the idle electric four-wheel drive mode to the power split mode.

9. A vehicle mode switching system, characterized in that, The vehicle includes an engine, a clutch, a first motor, and a transmission; the transmission includes a power split mechanism, a first synchronizer, and a transmission input shaft. The engine is connected to the first input end of the power split mechanism through the clutch, the first motor is connected to the second input end of the power split mechanism, the output end of the power split mechanism is connected to the transmission input shaft, and the first synchronizer is arranged between the first input end and the output end; the system includes a vehicle controller, a transmission controller, a motor controller, and an engine controller; wherein, The vehicle controller is configured to send a first status holding request to the engine controller and a second status holding request to the transmission controller when detecting that the vehicle is started; The engine controller is configured to control the engine to start and be in an idle state in response to the first status holding request; the transmission controller is configured to control the clutch to be in an open state in response to the second status holding request; The vehicle controller is further configured to send a motor torque regulation request to the motor controller when the vehicle meets the mode switching condition for switching from the idle electric four-wheel drive mode to the power split mode; The motor controller is configured to regulate the torque of the first motor in response to the motor torque regulation request so that the first synchronizer meets the gear shifting condition; The vehicle controller is further configured to send a synchronizer shifting request to the transmission controller when the first synchronizer meets the gear shifting condition; The transmission controller is configured to control the first synchronizer to switch from the engaged gear to the power split gear in response to the synchronizer shifting request; The vehicle controller is further configured to send a motor speed regulation request to the motor controller when the first synchronizer is in the power split gear; The motor controller is further configured to regulate the speed of the first motor in response to the motor speed regulation request so that the clutch switches from the open state to the closed state; The vehicle controller is further configured to send an engine torque output request to the engine controller when the clutch is in the closed state; The engine controller is further configured to control the engine to output torque in response to the engine torque output request so that the vehicle switches from the idle electric four-wheel drive mode to the power split mode.

10. A vehicle, characterized in that, Comprising the vehicle mode switching system according to claim 9.

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