Mode switching control system and method for a hybrid at transmission

Abstract

The application discloses a mode switching control system and method of a hybrid AT transmission, which comprises the following steps: a TCU control unit receives a HCU mode switching instruction and feeds back actual states of a power chain and a clutch to the HCU; an EMS control unit collects engine speed and torque signals and sends the signals to the TCU and HCU control units and responds to speed and torque requests; an MCU control unit collects motor speed and torque signals and sends the signals to the TCU and HCU control units and responds to speed and torque requests; a BMS control unit collects battery power signals and sends the signals to the HCU control unit; the HCU control unit exchanges information with a driver, the BMS, the TCU, the EMS and the MCU control unit, judges and sends mode switching instructions, controls opening and closing of a K0 clutch, adjusts engine and motor speed and torque, and completes mode switching of the hybrid AT transmission. The application solves the problem of poor coordination of speed control and torque control, improves the driving experience of the driver, and ensures the smoothness of the driving mode switching process.

Description

Technical Field

[0001] This invention belongs to the field of automotive technology and relates to a mode switching control system and method for a hybrid automatic transmission. Background Technology

[0002] Hybrid technology, as a crucial development direction for the entire automotive industry, uses both an engine and an electric motor as the power source for a vehicle, achieving the goals of reducing fuel consumption and increasing power. Hybrid automatic transmissions (AT transmissions) are also a hot topic, but the technology is still not mature enough. Different OEMs and suppliers have their own implementation methods for controlling the switching between different modes. During the transition from pure electric to hybrid mode in hybrid vehicles, power loss, abrupt changes in motor torque, and poor coordination between speed and torque control may occur, potentially damaging the motor and engine and reducing their lifespan. Summary of the Invention

[0003] The purpose of this invention is to solve the problem of poor coordination between speed control and torque control in the prior art, which damages the motor and engine and reduces their lifespan. The invention provides a mode switching control system and method for a hybrid automatic transmission.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A mode switching control system for a hybrid automatic transmission includes: an HCU control unit, an EMS control unit, an MCU control unit, a BMS control unit, a TCU control unit, and a hybrid automatic transmission;

[0006] The BMS control unit, EMS control unit, MCU control unit, and TCU control unit are all connected to the HCU control unit; the EMS control unit and MCU control unit are both connected to the TCU control unit; the TCU control unit sends clutch control commands and solenoid valve control commands to the hybrid AT transmission.

[0007] The HCU control unit receives signals from the BMS control unit, EMS control unit, and MCU control unit, and sends a mode switching command to the TCU control unit. Based on the received signals and the mode switching command from the HCU control unit, the TCU control unit sends powertrain status, clutch status, electric pump speed, input shaft speed, and requested torque signals to the HCU control unit. The HCU control unit monitors the signals sent by the TCU control unit and determines whether to perform a mode switch. If so, the HCU control unit adjusts the engine speed and torque of the EMS control unit, adjusts the motor speed and torque of the MCU control unit, and controls the opening and closing of the K0 clutch to complete the mode switch of the hybrid AT transmission.

[0008] A further improvement of the present invention is that:

[0009] Furthermore, the HCU control unit monitors the powertrain status, clutch status, electric pump speed, input shaft speed, and requested torque signals sent by the TCU control unit to determine whether to perform a mode switch. Specifically, if the powertrain is in a connected state, the clutch is in an open state, the electric pump speed and input shaft speed both reach the threshold, and the requested torque is within the set range, then the conditions for mode switching are met; the threshold and the range of requested torque are both manually set.

[0010] Furthermore, the HCU control unit receives signals from the BMS control unit, EMS control unit, and MCU control unit. Specifically, the BMS control unit sends a battery power signal to the HCU control unit; the EMS control unit collects engine speed and torque signals and sends them to the HCU control unit; and the MCU control unit collects motor speed and torque signals and sends them to the HCU control unit.

[0011] Furthermore, the signals received by the TCU control unit are: the EMS control unit collects the engine speed and torque signals and sends them to the TCU control unit; the MCU control unit collects the motor speed and torque signals and sends them to the TCU control unit.

[0012] Furthermore, when the HCU control unit adjusts the engine speed and torque of the EMS control unit and the motor speed and torque of the MCU control unit, it also includes sending charging or discharging commands to the BMS control unit.

[0013] Furthermore, when the HCU control unit receives signals from the BMS control unit, EMS control unit, and MCU control unit, it also includes: the HCU control unit collecting the driver's motion mode switching request.

[0014] A mode switching control method for a hybrid automatic transmission, comprising:

[0015] Detect the operating mode of the hybrid automatic transmission while driving;

[0016] If it is in pure electric mode, the HCU control unit detects whether there is a mode switching command to switch from pure electric mode to hybrid electric mode. If so, the HCU control unit and TCU control unit coordinate to control the electric motor and engine to perform the EV2HEV mode switching operation; at the same time, it judges the K0 clutch status; if the clutch is in the closed state and the speed difference between the engine and the electric motor is less than the threshold, the conversion from pure electric mode to hybrid electric mode is completed; the threshold is set manually.

[0017] If it is in hybrid electric mode, the HCU control unit detects whether there is a mode switching command to switch from hybrid electric mode to pure electric mode. If so, the HCU control unit and TCU control unit control the electric motor and engine to perform the HEV2EV mode switching operation, and at the same time determine the K0 clutch status. If the clutch is in the disengaged state and the engine speed is zero, the conversion from hybrid electric mode to pure electric mode is completed.

[0018] Furthermore, the mode switching command for switching from pure electric mode to hybrid electric mode is: the battery charge is less than the charge threshold, the driver's torque demand is greater than the torque threshold, or the driver actively requests to switch modes; the charge threshold and torque threshold are both manually set.

[0019] Furthermore, the HCU control unit and TCU control unit control the electric motor and engine to perform the EV2HEV mode switching operation, completing the conversion from pure electric mode to hybrid electric mode, specifically:

[0020] After receiving the EV2HEV mode switching operation command, the HCU control unit starts the engine and sends the K0 clutch engagement command, while simultaneously sending a shift prohibition signal to the TCU control unit.

[0021] The TCU control unit responds to the K0 clutch engagement command and shift prohibition, and fills the torque of the K0 clutch. At the same time, it sends the speed request target and the information that the TCU is performing clutch slippage start to the HCU control unit.

[0022] The TCU control unit controls the K0 clutch to expand its torque capacity and tow the engine.

[0023] The HCU control unit receives the target speed request and controls the engine to synchronize to the target value. The TCU control unit determines that the engine has started successfully and sends a message to the HCU control unit indicating that the clutch slippage start has been completed.

[0024] The TCU control unit determines whether the engine and electric motor have completed synchronization based on the engine speed and electric motor speed; the TCU control unit engages the K0 clutch, and after the clutch is engaged, it sends the actual state of the K0 clutch as closed to the HCU control unit.

[0025] The HCU control unit determines that the EV to HEV transition is complete, and sends the actual status of the K0 clutch. At the same time, the torque alternation between the engine and the electric motor will occur after the actual status of the K0 clutch is closed.

[0026] Furthermore, the TCU control unit controls the K0 clutch to expand its torque capacity and tow the engine; specifically, the TCU control unit increases the torque capacity of the K0 clutch and tows the engine. Once the engine speed approaches the idle speed, it releases the torque capacity of the K0 clutch. Throughout the entire control process, the actual torque of the K0 clutch is sent to the HCU control unit in real time. The HCU control unit receives the actual torque of the K0 clutch and controls the motor to adjust the torque. The adjustment amount is to maintain the torque required by the driver while additionally synchronizing the actual torque of the K0 clutch. The idle speed is 700 to 800 revolutions per minute.

[0027] Furthermore, before the TCU control unit determines that the engine has started successfully, the following steps are also taken: the TCU control unit keeps the K0 clutch engaged at the half-disengagement point (Kiss point), that is, when the K0 clutch just engages, the actual torque is 0, and sends the actual torque of the K0 clutch to the HCU control unit in real time throughout the entire control process.

[0028] Furthermore, the mode switching command for switching from hybrid electric mode to pure electric mode is: the battery charge is greater than the charge threshold, the driver's torque demand is less than the torque threshold, or the driver actively requests to switch modes; the charge threshold and torque threshold are both manually set.

[0029] Furthermore, the HCU control unit and TCU control unit control the electric motor and engine to perform the HEV2EV mode switching operation, completing the conversion from hybrid electric mode to pure electric mode, specifically:

[0030] After receiving the HEV2EV mode switching command, the HCU control unit shuts down the engine and sends a K0 clutch open command, while simultaneously sending a shift prohibition signal to the TCU control unit. The TCU control unit responds to the K0 clutch open command and shift prohibition, the K0 clutch synchronizes with the engine torque and releases its torque capacity to ensure that the K0 clutch torque capacity is higher than the engine torque, and simultaneously sends an engine stop prohibition signal. The actual torque of the K0 clutch and the K0 clutch state of slip are sent to the HCU control unit.

[0031] The TCU control unit continues to maintain the torque capacity of the K0 clutch, which is higher than zero torque, while sending the actual torque of the K0 clutch to the HCU control unit. After the engine speed is lower than the threshold, the K0 clutch is fully disengaged and the actual state of the K0 clutch is sent to the HCU control unit as disengaged. The HCU control unit automatically controls the engine to stop, while the TCU control unit requires that the engine stop be implemented when the engine torque is 0. The HCU control unit determines that the actual state of the K0 clutch is disengaged and the engine speed is 0; then the conversion from hybrid electric mode to pure electric mode is completed.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] This invention solves the problem of poor coordination between speed control and torque control by having the HCU control unit and TCU control unit interact during driving mode switching to control clutch engagement and disengagement, and adjust the torque and speed of the engine and motor. This improves the driver's driving experience and ensures the smoothness of the entire driving mode switching process. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a structural diagram of the mode switching control system of the hybrid AT transmission of the present invention;

[0036] Figure 2 This is a flowchart of the mode switching control method for the hybrid AT transmission of the present invention;

[0037] Figure 3 This is a schematic diagram illustrating the switching between EV mode and HEV mode according to the present invention;

[0038] Figure 4 This is a schematic diagram of the EV2HEV mode switching control of the present invention;

[0039] Figure 5 This is a schematic diagram of the HEV2EV mode switching control of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0042] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0043] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0044] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0046] The present invention will now be described in further detail with reference to the accompanying drawings:

[0047] In this invention, the mode switching control of the hybrid automatic transmission requires receiving message information from relevant nodes in the vehicle network. Based on vehicle-related information and the current mode status of the transmission, it determines whether to switch to another mode. If the current mode is EV (pure electric), it determines that it can enter HEV (hybrid electric vehicle) mode and controls it according to the EV2HEV control method. If the current mode is HEV, it determines that it can enter EV mode and controls it according to the HEV2EV control method. During the control process, it is necessary to continuously exchange message information with the vehicle and send control commands to the internal hydraulic system of the transmission.

[0048] The entire control system in this invention includes the HCU control unit, EMS control unit, MCU control unit, BMS control unit, TCU control unit, and hybrid automatic transmission in the vehicle, such as... Figure 1 .

[0049] The BMS control unit, EMS control unit, MCU control unit, and TCU control unit are all connected to the HCU control unit; the EMS control unit and MCU control unit are both connected to the TCU control unit; the TCU control unit sends clutch control commands and solenoid valve control commands to the hybrid AT transmission.

[0050] The HCU control unit receives signals from the BMS control unit, EMS control unit, and MCU control unit, and sends a mode switching command to the TCU control unit. Based on the received signals and the mode switching command from the HCU control unit, the TCU control unit sends powertrain status, clutch status, electric pump speed, input shaft speed, and requested torque signals to the HCU control unit. The HCU control unit monitors the signals sent by the TCU control unit and determines whether to perform a mode switch. If so, the HCU control unit adjusts the engine speed and torque of the EMS control unit, adjusts the motor speed and torque of the MCU control unit, and controls the opening and closing of the K0 clutch to complete the mode switch of the hybrid AT transmission.

[0051] The HCU control unit monitors the powertrain status, clutch status, electric pump speed, input shaft speed, and requested torque signals sent by the TCU control unit to determine whether to switch modes. Specifically, if the powertrain is in the connected state, the clutch is in the open state, the electric pump speed and input shaft speed both reach the threshold, and the requested torque is within the set range, then the conditions for mode switching are met. The threshold and the range of requested torque are both manually set.

[0052] The HCU control unit receives signals from the BMS control unit, EMS control unit, and MCU control unit, specifically:

[0053] The BMS control unit sends the battery power signal to the HCU control unit; the EMS control unit collects the engine speed and torque signals and sends them to the HCU control unit; the MCU control unit collects the motor speed and torque signals and sends them to the HCU control unit.

[0054] The signals received by the TCU control unit are as follows: the EMS control unit collects the engine speed and torque signals and sends them to the TCU control unit; the MCU control unit collects the motor speed and torque signals and sends them to the TCU control unit.

[0055] When the HCU control unit adjusts the engine speed and torque of the EMS control unit and the motor speed and torque of the MCU control unit, it also includes sending charging or discharging commands to the BMS control unit.

[0056] When the HCU control unit receives signals from the BMS control unit, EMS control unit, and MCU control unit, it also collects the driver's motion mode switching request.

[0057] In this invention, during the vehicle's switch from EV mode to HEV mode, the hybrid automatic transmission goes through the following states: pure electric mode, clutch engagement, engine drag, speed synchronization, clutch engagement, and hybrid mode. During the vehicle's switch from HEV mode to EV mode, the hybrid automatic transmission goes through the following states: hybrid mode, clutch dynamic engagement, clutch disengagement, and pure electric mode. The clutch mentioned above refers to the engine engagement / disengagement clutch, denoted by K0 in the following description.

[0058] See Figure 2 This invention discloses a mode switching control method for a hybrid automatic transmission, comprising:

[0059] S101 detects the operating mode of the hybrid automatic transmission while driving.

[0060] S102, if in pure electric mode, the HCU control unit detects whether a mode switching command to switch from pure electric mode to hybrid electric mode has been issued. If so, the HCU control unit and TCU control unit coordinate to control the electric motor and engine to perform the EV2HEV mode switching operation; at the same time, it judges the K0 clutch status; if the clutch is in the closed state and the speed difference between the engine and the electric motor is less than the threshold, the conversion from pure electric mode to hybrid electric mode is completed. The threshold is manually set.

[0061] See Figure 3 The mode switching command for switching from pure electric mode to hybrid electric mode is: the battery charge is less than the charge threshold, the driver's torque demand is greater than the torque threshold, or the driver actively requests to switch modes; the charge threshold and torque threshold are both manually set.

[0062] The HCU control unit and TCU control unit control the electric motor and engine to perform the EV2HEV mode switching operation, completing the conversion from pure electric mode to hybrid electric mode, specifically:

[0063] After receiving the shift command, the HCU control unit starts the engine and sends the K0 clutch engagement command, while simultaneously sending a shift prohibition signal to the TCU control unit.

[0064] The TCU control unit responds to the K0 clutch engagement command and shift prohibition, and fills the torque of the K0 clutch. At the same time, it sends the speed request target and the information that the TCU is performing clutch slippage start to the HCU control unit.

[0065] The TCU control unit controls the K0 clutch to expand its torque capacity and tow the engine.

[0066] The HCU control unit receives the target speed request and controls the engine to synchronize to the target value. The TCU control unit determines that the engine has started successfully and sends a message to the HCU control unit indicating that the clutch slippage start has been completed.

[0067] The TCU control unit determines whether the engine and electric motor have completed synchronization based on the engine speed and electric motor speed; the TCU control unit engages the K0 clutch, and after the clutch is engaged, it sends the actual state of the K0 clutch as closed to the HCU control unit.

[0068] The HCU control unit determines that the EV to HEV transition is complete, and sends the actual status of the K0 clutch. At the same time, the torque alternation between the engine and the electric motor will occur after the actual status of the K0 clutch is closed.

[0069] The TCU control unit controls the K0 clutch to increase its torque capacity and tow the engine. Specifically, the TCU control unit increases the torque capacity of the K0 clutch and tows the engine. Once the engine speed approaches idle speed, it releases the torque capacity of the K0 clutch. Throughout the control process, the actual torque of the K0 clutch is sent to the HCU control unit in real time. The HCU control unit receives the actual torque of the K0 clutch and controls the motor to adjust the torque. The adjustment is to maintain the torque required by the driver while additionally synchronizing with the actual torque of the K0 clutch. The idle speed is 700 to 800 revolutions per minute.

[0070] Before the TCU control unit determines that the engine has started successfully, the following steps are also taken: The TCU control unit keeps the K0 clutch engaged at the half-disengagement point, that is, when the K0 clutch just engages, the actual torque is 0, and sends the actual torque of the K0 clutch to the HCU control unit in real time throughout the entire control process.

[0071] S103, if it is a hybrid electric vehicle (HEV) mode; the HCU control unit detects whether there is a mode switching command to switch from hybrid electric vehicle (HEV) mode to pure electric vehicle (PEV) mode. If so, the HCU control unit and the TCU control unit control the electric motor and engine to perform the HEV2EV mode switching operation. At the same time, the K0 clutch status is judged. If the clutch is in the disengaged state and the engine speed is zero, the conversion from hybrid electric vehicle (HEV) mode to pure electric vehicle (PEV) mode is completed.

[0072] See Figure 3 The mode switching command for switching from hybrid electric mode to pure electric mode is: the battery charge is greater than the charge threshold, the driver's torque demand is less than the torque threshold, or the driver actively requests to switch modes; the charge threshold and torque threshold are both manually set.

[0073] The HCU control unit and TCU control unit control the electric motor and engine to perform the HEV2EV mode switching operation, completing the conversion from hybrid electric mode to pure electric mode, specifically:

[0074] After receiving the HEV2EV mode switching command, the HCU control unit shuts down the engine and sends a K0 clutch open command, while simultaneously sending a shift prohibition signal to the TCU control unit. The TCU control unit responds to the K0 clutch open command and shift prohibition, the K0 clutch synchronizes with the engine torque and releases its torque capacity to ensure that the K0 clutch torque capacity is higher than the engine torque, and simultaneously sends an engine stop prohibition signal. The actual torque of the K0 clutch and the K0 clutch state of slip are sent to the HCU control unit.

[0075] The TCU control unit continues to maintain the torque capacity of the K0 clutch, which is higher than zero torque, while sending the actual torque of the K0 clutch to the HCU control unit. After the engine speed is lower than the threshold, the K0 clutch is fully disengaged and the actual state of the K0 clutch is sent to the HCU control unit as disengaged. The HCU control unit automatically controls the engine to stop, while the TCU control unit requires that the engine stop be implemented when the engine torque is 0. The HCU control unit determines that the actual state of the K0 clutch is disengaged and the engine speed is 0; then the conversion from hybrid electric mode to pure electric mode is completed.

[0076] Example:

[0077] The EV2HEV control method described in this invention, after determining that a switch from EV mode to HEV mode is needed, executes the following process, see below. Figure 4 :

[0078] 0: The current mode is EV. The HCU control unit considers factors such as battery level, torque demand, and driver requests to determine whether to switch to HEV mode.

[0079] 0->1 switching: After the HCU control unit determines that the engine needs to be started, it sends a K0 clutch engagement command and at the same time sends a shift prohibition signal;

[0080] 1: The TCU control unit responds to the K0 clutch engagement command and shift prohibition, begins to perform K0 clutch filling, and simultaneously sends the speed request target and the information that the TCU is performing clutch slippage start to the HCU control unit;

[0081] 1->2 switching: The TCU control unit determines that the K0 clutch is fully filled.

[0082] 2-a: The TCU control unit increases the torque capacity of the K0 clutch to drag the engine. After the engine speed approaches the idle speed, the torque capacity of the K0 clutch is released. Throughout the control process, the actual torque of the K0 clutch is sent to the HCU control unit in real time.

[0083] 2-b: The HCU control unit receives the actual torque of the K0 clutch and controls the motor to adjust the torque. The adjustment amount is to maintain the torque required by the driver and additionally synchronize the actual torque of the K0 clutch. The purpose is to compensate for the torque loss caused by the dragging of the K0 clutch during the engine start-up process.

[0084] 2->3 switch: The TCU control unit determines that the engine has started successfully and sends a message to the HCU control unit to complete the clutch slippage start.

[0085] 3-a: The TCU control unit keeps the K0 clutch engaged at the half-disengagement point, i.e., the actual torque of the K0 clutch is 0. Throughout the control process, the actual torque of the K0 clutch is sent to the HCU control unit in real time.

[0086] 3-b: The HCU control unit receives the target speed request and controls the engine to synchronize to the target value. At this time, the HCU control unit will not refer to the actual torque of the K0 clutch to compensate the motor torque.

[0087] 3->4 switching: Based on the engine speed and motor speed, the TCU control unit determines that engine synchronization is complete.

[0088] 4-a: The TCU control unit quickly engages the K0 clutch. After the clutch engagement is complete, it sends the actual state of the K0 clutch as Lock to the HCU control unit. Throughout the entire control process, it sends the actual torque of the K0 clutch to the HCU control unit in real time.

[0089] 4-b: The HCU control unit cannot refer to the actual torque of the K0 clutch to compensate for the motor torque, and the alternation of engine and motor torque will not occur.

[0090] 4->5 Switching: The HCU control unit determines that the EV to HEV transition is complete, and the TCU control unit sends the actual status of the K0 clutch. At the same time, the torque alternation between the engine and the motor will occur after the actual status of the K0 clutch is Locked.

[0091] The HEV2EV control method described in this invention, after determining that a switch from HEV mode to EV mode is needed, executes the following process, see below. Figure 5 :

[0092] 0: The current mode is HEV. The HCU control unit considers factors such as battery level, torque demand, and driver requests to determine whether to switch to EV mode.

[0093] 0->1 switching: After the HCU control unit determines that the engine needs to be shut off, it sends a K0 clutch disengagement command and simultaneously issues a shift prohibition signal.

[0094] 1-a: The HCU control unit performs the task of alternating motor and engine torque;

[0095] 1-b: The TCU control unit responds to the K0 clutch open command and shift prohibition. The K0 clutch releases torque capacity in sync with the engine torque. During the process, the torque capacity of the K0 clutch is kept slightly higher than the engine torque. At the same time, the TCU control unit sends an engine stop prohibition signal. The actual torque and K0 clutch status are slipped to the HCU control unit.

[0096] 1->2 switching: The TCU control unit determines that the alternation of motor and engine torque is completed when the engine torque is 0.

[0097] 2-a: The TCU control unit continues to maintain the torque capacity of the K0 clutch slightly higher than 0 Nm, while sending the actual torque of the K0 clutch to the HCU control unit. After the engine speed is lower than the threshold, the K0 clutch is fully opened and the actual state of the K0 clutch is sent to the HCU control unit as Open.

[0098] 2-b: The HCU control unit automatically shuts down the engine, while the TCU control unit requires that the engine shutdown be implemented some time after the engine torque reaches 0.

[0099] 2->3 switching: The HCU control unit determines that the actual state of the K0 clutch is Open and the engine speed is 0, then the HEV to EV conversion is completed. The TCU control unit sends the actual state of the K0 clutch.

[0100] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A mode switching control system for a hybrid automatic transmission, characterized in that, include: HCU control unit, EMS control unit, MCU control unit, BMS control unit, TCU control unit, hybrid AT transmission; The BMS control unit, EMS control unit, MCU control unit, and TCU control unit are all connected to the HCU control unit; the EMS control unit and MCU control unit are both connected to the TCU control unit; the TCU control unit sends clutch control commands and solenoid valve control commands to the hybrid AT transmission. The HCU control unit receives signals from the BMS control unit, EMS control unit, and MCU control unit, and sends a mode switching command to the TCU control unit. Based on the received signals and the mode switching command sent by the HCU control unit, the TCU control unit sends powertrain status, clutch status, electric pump speed, input shaft speed, and requested torque signals to the HCU control unit. The HCU control unit monitors the signals sent by the TCU control unit and determines whether to perform a mode switch. If so, the HCU control unit adjusts the engine speed and torque of the EMS control unit, adjusts the motor speed and torque of the MCU control unit, and controls the opening and closing of the K0 clutch to complete the mode switch of the hybrid AT transmission. The HCU control unit monitors the powertrain status, clutch status, electric pump speed, input shaft speed, and requested torque signals sent by the TCU control unit to determine whether to switch modes. Specifically, if the powertrain is in a connected state, the clutch is in an open state, the electric pump speed and input shaft speed both reach the threshold, and the requested torque is within the set range, then the conditions for mode switching are met. The threshold and the range of requested torque are both manually set. The HCU control unit receives signals from the BMS control unit, EMS control unit, and MCU control unit, specifically: The BMS control unit sends the battery power signal to the HCU control unit; the EMS control unit collects the engine speed and torque signals and sends them to the HCU control unit; the MCU control unit collects the motor speed and torque signals and sends them to the HCU control unit. The signals received by the TCU control unit are as follows: the EMS control unit collects the engine speed and torque signals and sends them to the TCU control unit; the MCU control unit collects the motor speed and torque signals and sends them to the TCU control unit.

2. The mode switching control system for the hybrid automatic transmission according to claim 1, characterized in that, When the HCU control unit adjusts the engine speed and torque of the EMS control unit and the motor speed and torque of the MCU control unit, it also includes: the HCU control unit sending charging or discharging commands to the BMS control unit. When the HCU control unit receives signals from the BMS control unit, EMS control unit, and MCU control unit, it also includes: the HCU control unit collecting the driver's motion mode switching request.

3. A mode switching control method for a hybrid automatic transmission based on the system described in claim 1, characterized in that, include: Detect the operating mode of the hybrid automatic transmission while driving; If it is in pure electric mode, the HCU control unit detects whether there is a mode switching command to switch from pure electric mode to hybrid electric mode. If so, the HCU control unit and TCU control unit coordinate to control the electric motor and engine to perform the EV2HEV mode switching operation; at the same time, it judges the K0 clutch status; if the clutch is in the closed state and the speed difference between the engine and the electric motor is less than the threshold, the conversion from pure electric mode to hybrid electric mode is completed; the threshold is set manually. If it is in hybrid electric mode, the HCU control unit detects whether there is a mode switching command to switch from hybrid electric mode to pure electric mode. If so, the HCU control unit and TCU control unit control the electric motor and engine to perform the HEV2EV mode switching operation, and at the same time determine the K0 clutch status. If the clutch is in the disengaged state and the engine speed is zero, the conversion from hybrid electric mode to pure electric mode is completed.

4. The mode switching control method for a hybrid automatic transmission according to claim 3, characterized in that, The mode switching command for switching from pure electric mode to hybrid electric mode is: the battery charge is less than the charge threshold, the driver's torque demand is greater than the torque threshold, or the driver actively requests to switch modes; the charge threshold and torque threshold are both manually set.

5. The mode switching control method for a hybrid automatic transmission according to claim 4, characterized in that, The HCU control unit and TCU control unit control the electric motor and engine to perform EV2HEV mode switching operations, completing the conversion from pure electric mode to hybrid electric mode, specifically: After receiving the EV2HEV mode switching operation command, the HCU control unit starts the engine and sends the K0 clutch engagement command, while simultaneously sending a shift prohibition signal to the TCU control unit. The TCU control unit responds to the K0 clutch engagement command and shift prohibition, and fills the torque of the K0 clutch. At the same time, it sends the speed request target and the information that the TCU is performing clutch slippage start to the HCU control unit. The TCU control unit controls the K0 clutch to expand its torque capacity and tow the engine. The HCU control unit receives the speed request target and controls the engine to synchronize to the speed request target. The TCU control unit determines that the engine has started successfully and sends a TCU to the HCU control unit to complete the clutch slippage start. The TCU control unit determines whether the engine and electric motor have completed synchronization based on the engine speed and electric motor speed; the TCU control unit engages the K0 clutch, and after the clutch is engaged, it sends the actual state of the K0 clutch as closed to the HCU control unit. The HCU control unit determines that the EV to HEV transition is complete, and sends the actual status of the K0 clutch. At the same time, the torque alternation between the engine and the electric motor will occur after the actual status of the K0 clutch is closed.

6. The mode switching control method for a hybrid automatic transmission according to claim 5, characterized in that, The TCU control unit controls the K0 clutch to expand its torque capacity and tow the engine; specifically: The TCU control unit increases the torque capacity of the K0 clutch and pulls the engine. Once the engine speed approaches the idle speed, it releases the torque capacity of the K0 clutch. Throughout the control process, the actual torque of the K0 clutch is sent to the HCU control unit in real time. The HCU control unit receives the actual torque of the K0 clutch and controls the motor to adjust the torque. The adjustment amount is to maintain the torque required by the driver and additionally synchronize the actual torque of the K0 clutch. The idle speed is 700 to 800 revolutions per minute.

7. The mode switching control method for a hybrid automatic transmission according to claim 6, characterized in that, Before the TCU control unit determines that the engine has started successfully, the following steps are also included: the TCU control unit keeps the K0 clutch engaged at the half-disengagement point (Kiss point), that is, when the K0 clutch just engages, the actual torque is 0, and sends the actual torque of the K0 clutch to the HCU control unit in real time throughout the entire control process.

8. The mode switching control method for a hybrid automatic transmission according to claim 3, characterized in that, The mode switching command for switching from hybrid electric mode to pure electric mode is: the battery charge is greater than the charge threshold, the driver's torque demand is less than the torque threshold, or the driver actively requests to switch modes; the charge threshold and torque threshold are both manually set.

9. The mode switching control method for a hybrid automatic transmission according to claim 8, characterized in that, The HCU control unit and TCU control unit control the electric motor and engine to perform HEV2EV mode switching operations, completing the conversion from hybrid electric mode to pure electric mode, specifically: After receiving the HEV2EV mode switching command, the HCU control unit shuts down the engine and sends a K0 clutch open command, while simultaneously sending a shift prohibition signal to the TCU control unit. The TCU control unit responds to the K0 clutch open command and shift prohibition, the K0 clutch synchronizes with the engine torque and releases its torque capacity to ensure that the K0 clutch torque capacity is higher than the engine torque, and simultaneously sends an engine stop prohibition signal. The actual torque of the K0 clutch and the K0 clutch state of slip are sent to the HCU control unit. The TCU control unit continues to maintain the torque capacity of the K0 clutch, which is higher than zero torque, while sending the actual torque of the K0 clutch to the HCU control unit. After the engine speed is lower than the threshold, the K0 clutch is fully disengaged and the actual state of the K0 clutch is sent to the HCU control unit as disengaged. The HCU control unit automatically controls the engine to stop, while the TCU control unit requires that the engine stop be implemented when the engine torque is 0. The HCU control unit determines that the actual state of the K0 clutch is disengaged and the engine speed is 0; then the conversion from hybrid electric mode to pure electric mode is completed.

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